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76- 75* 74* 73* % -39' Y 1d f "A StuY 0 r' Eftztts,:-@ D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Hi@pt O-n R o a sVa. LObntrazt Report [email protected] for 0 T S. Ar.Y Corps of Engineers N k District U, by 37 !.,'Xlirg'lnia IILStitute of Marine Science Sd-:@ool of Marine Science .-,',,'Coll6ge of William and Mary 2 Gl9kicester Point, Virginia 3062 130 1Z Walter I. Priest, III Editor k' SRAMSOE No. 247 TL -P rv TC1 87 .P75 76* 75* 7r 7r A S78 1981 A STUDY OF DREDGING EFFECTS IN HAMPTON ROADS, VIRGINIA Final Contract Report prepared for: U. S. Army Corps of Engineers Norfolk District 803 Front Street Norfolk, Virginia 23510 under Contract No. DACW65-78-C-0029 by Virginia Institute of Marine Science School of Marine Science College of William and Mary Gloucester Point, Virginia 23062 Walter I. Priest, III, Editor March, 1981 Special Report in Applied Marine Science and Ocean Engineering No. 247 Property of CSC Library US Department of Commerce NOAA Coastal Services Center Library 2234 South Hobson Avenue Charleston, SC 29405-2413 Table of Contents Page Introduction Marine Resource Descriptions Nekton Utilization of Aquatic Resources in the Elizabeth'and the Lower James Rivers by M. Y. Hedgepeth, J V. Merriner and. F. Wojick ....... loo, ............... I........................ Oyster and Hard Clam Distribution and Abundance in Hampton Roads and the Lower James River. by D. S. Haven, R. Morales@ Alamo and W. I..Priest ..... o ................................... 38 Spawning Activity and Nursery Utilization by Fishes in Hampton Roads and its Tributaries by W. I. Priest .............. 49 Model and Physical Environment, A Model for Dredge-Induced Turbidity.by A. Y. Kuo and R. J. Lukens ........... o....... ;..o ............................ 55 Suspended Sediment Experiment and Model Calibration by C.S. Welch, R.J. Lukens and A.Y. Kuo ....... o ................ 130 Near Bottom Currents.in the Lower-James and Elizabeth Rivers by C. S. Welch .................. o ......................... 201 Elizabeth River.Surface Circulation Atlas by J. C.. Munday, H. H. Gordon and C. J. Alston .......................... 236 Dredging Effects The Effects of Dredging Impacts on Water Quality and Estuarine Organisms by W. I. Priest ........................ o ............ 240 Summary and Conclusions ............................................ 262 Introduction The environmental consequences of dredging and spoil disposal are among the'most extensively studied of all of the impacts associated with construction activities performed in aquatic ecosystems. Because the dredged material must be disposed of, the operations are often con- sidered synonymous. This. can present problems when assessing the environ- mental impacts of a project becausethe majority of adverse impacts are associated with the disposaloperations in open-water.rather than the dredging per se. This synonymy is unfortunate when.the dredged material is being placed in a confined.upland site'whereby a major portion of the adverse impacts to the environment are being eliminated or greatly reduced., The intent-of this report is to identify and,quantifyj in part, the adverse effects associated with the dredging operation itself and those segments of the ecological community which might be adversely-affected by the levels of suspended solids and sedimentation attributable to the dredge. It consists,of three sections including: a comprehensive review of the major marine resources, their location in and utilization of the Hampton Roads Harbor and.vicinity; the turbidity model and physical environ- ment, describing the levels and distribution of'suspended sediment and sedimentation and local current patterns; and a review of the effects of increased suspended sediment loads on estuarine organisms and water quality. The first section onmarine resources1contains chapters of. finfish, shellfish and ichthyoplankton. The.finfish report summarizes the results of comprehensive trawl surveys performed during 1978 and 1979..' These data were analyzed for the seasonal distribution of both resident and migratory species and.nursery areas utilized by juveniles. 2 The shellfish report details the distribution of the oyster,.Crassostrea virginica, and the hard clam, Mercenaria mercenaria, in Hampton Roads and the lower James River. The oyster data are based on the different. densities of oysters associated with three types of substrate, oyster-rock, mud and shell and sand and shell, which represent the areas where oyster' populations are densest. Also included are data.on oyster sp atfall for the years 1976-1979 at selected stations in the study area. The hard clam data depict their distribution and abundance in the Hampton Roads area. The ichthyoplankton chapter reports the seasonal distribution of fish eggs and larvae in and near the study area based on recent research. The data from the lower Chesapeake Bay can be extrapolated to a limited extent to include Hampton Roads and that from the Southern Branch of the Elizabeth River is directly applicable to other Hampton Roads tributaries. The first.two, chapters of the second section of this report describe the model and the field calibration experiments developed to predict the distribution of dredge-induced suspended solids and sedimentation and the various facets of the dredging operation which influence their generation and distribution. Also included in this section are detailed descriptions of the surface And near bottom currents in.the study area which also affect the.distribution of the suspended solids. The final section of this report presents a review of the literature concerning the environmental impacts of increased suspended solids levels created by dredging. These impacts include: increased.turbidity levels, changes in dissolved oxygen, sedimentation and their effects on various estuarine organisms. This report.is intended to provide an effective scheme for the evaluation of the impacts of dredging in the Hampton Roads area. By providing detailed quantified distributional data on the important resources of the area, an accurate means of predicting the distribution of increased suspended solids levels and a means of approximating which organisms are going to be affected by the predicted increase, it is hoped that well informed decisions can be made regarding dredging activities in Hampton Roads. 0 0 0 0 MARINE RESOURCE DESCRIPTIONS 0 0 0 0 0 Nekton Utilization of Aquatic 'Resources in the Elizabeth River and the Lower James River by Marion Y. Hedgepeth, John V. Merriner and Frank Wojcik Virginia Institute of Marine,Science School.bf Marine Science College of William and Mary Gloucester Point, Virginia 23062 March, 1981 4 Nekton Utilization of Aquatic Resources in the Elizabeth River and the Lower James River by Marion Y. Hedgepeth, John V. MerriPer and Frank Wojcik Introduction The Chesapeake Bay and its tributaries provide the state of Virginia with some if its' greatest natura 1 resources. Our ,blue crab, oyster and finfish industries are three of the largest commercial fisheries on the east coast of the United States. Although a maj,.or portion of one of Virginia's largest tributary systems (the James River) has been closed to most shellfishing and finfishing since.1976 due to Kepone contamination, it still provides seasonal and permanent residence for large populations of shellfish and finfish. The lower James River area'(Hampton Roads) and the Elizabeth River provide an estuarine habitat for many commercially and recreationally important species. For example, the Elizabeth River and the lower James River are important nursery grounds for spot, Atlantic croaker, Atlantic menhaden, weakfish, striped bass@, black seabass, and summer flounder. Furthermore, they are important as feeding grounds for adult bluefish,.weakfish, spot, and Atlantic croaker. Anadromous species such as-striped"bass, AmerIican shad, blueback herring and alewife travel through thes e areas to reach their freshwater spawning grounds. 5 The purpose of this study was to investigate nekton utilization of the Elizabeth River and the lower James River and to establish specific uses. Subsequently, this information would be used by the Army Corps of Engineers for-scheduling dredging pro jects 'at times and locations for least impact on the nekton community. Studies by Virginia Institute of Marine Science (VIMS, Musick et al.,-1972 and Rooney-Char, and Ayres, 1978), and the*U.S. Army Corps of Engineers (1977) address ed several problems associated with dredging operations and Pipeline landfall sites in our 0 present study areas. They concluded that the two major impacts would be the removal of benthic organisms which serve as fish food and the resusnension of sediments. The latter would 0 affect fish by increasing turbidity, altering respiration rates and predator-prey behavior,.and by resuspending heavy metals or other toxic substances present. In a report on water quality in the Elizabeth River, Nielson et al. (1978) cited high levels of heavy metals in bottom sediments and high levels of fecal coliforms in water samples. These data suggest that environmental impacts in the Hampton Roads and.' Elizabeth River must be examined in detail before dredging Permits are issued. 6 Study Area and Methods The areas included in the nekton resource survey were the eastern, southern,-and western branches of the-Elizabeth River and the lower James River from the Hampton Roads Bridge Tunnel to the James'River Bridge (approximately mile ten). Bottom trawl surveys utilizing lined 16-foot (5-meter) semi- balloon trawls were conducted on the Elizabeth River during 1978 and 1979. During the month of Auqust, 1978, 22 random stations (Fig. 1) were made in the southern-branch of the Elizabeth River. A 4.2- foot,(13-meter) commercial boat, The Three Daughters,was sub-contracted for this survey. In all subsequent Elizabeth River surveys the R/V Restless, a 32-foot (10-meter) vessel,was used. During March, 1978, three fixed stations (Fig. 1) were made in the southern branch. These stations were approximately located at the upper, middle and lower portions of the river. Again, in February, 1979, 22 random stations were made in the southern branch, while 9 fixed stations (three in each branch) were made in August, 1979, (Fig. 2). 0 Thirty-foot, (9-meter), lined semi-balloon trawls were .used on the surveys of the lower James River. Thirty random stations (Fig. 3) were made in this area during February, 1978 from the R/V Langley, an 80-foot (24-meter) steel ferryboat. Trawl data from July, 1978 (consisting of 34 random stations, Fig. 3) and January, 1979 (consisting of 30 random stations, Fig. 4) were taken in conjunction'with a KePone Biomass Study 7 of the James River. Trawl data (consisting of 2 stations) from July..' 1979 were taken during a VIMS Crustaceology-Ichthyology Monitoring Survey conducted with the R/V Pathfinder, a 55-foot (17-meter) vessel. After each five minute tow, fish were identified, counted and weighed by species. Whenever possible, 50 fish of a species were measured for total length in millimeters. Blue crabs were counted, and scored (tallied) by sex and stage of develonment. Water quality observations were obtdined from surface and bottom readings of dissolved oxygen (mg/1), salinity (ppt.) and temperature'('C). Secchi disk readings (in meters) were used to describe water clarity. 8 RESULTS Fish Distributions in the Elizabeth River During the 1978 Winter Survey, only two fish were captured (a hogchoker and a juvenile.blueback herring); therefore, no table was prenared. Water temperatures ranged from 2-7*C. Many species which overwinter in the rivers probably migrateO. just outside of the mouth of the Chesapeake Bay'or offshore. The 1979 Winter Survey yielded 18 species and a total of 657 fish, (Table 1). The most abundant species were juvenile spot, Atlantic croaker, blueback herring and alewife. Spot, striped bass, American eel, hogchokers and river herring accounted for 90-percent of the total biomass. Juvenile spot and striped bass were only collected upstream of Mains Creek, (Figs. 5 and 6).. Spot ranged in total length from 73-151 millimeters, while striped bass ranged in total length from 117-197 millimeters. Water temperatures below Mains Creek were 8-9'C, while those around Craney Island were 4.3-5.3'C. Atlantic croaker were collected throughout the river, (Fig. 7). Most of these fish were less than 50 millimeters in total length. Winter kills of Atlantic croaker were noted in trawls made near New Mill Creek, Town Point and upriver from Jones Creek. Alosines (blueback herring, alewife and American shad) were also collected throughout the river, (Fiq. 8). Blueback herring dominated most of the catch of alosines; however, at .9 Milldam Creek, alewife constituted 99 percent of the catch.. Alosines varied in length from 46-170 millimeters. Summer surveys usuallyprovided more species, more. individuals and largetfish.. Seventeen species and 3,912 fish were collected in August 1978 fromthe southern branch. Bay anchovy, spot and weakfish were the most abundant species, (Table 2). Biomass M*ainly consisted of spot, hogchoker, Atlantic croaker, summer flounder and weakfish. Water temperatures between 26.9 and 32*C were recorded. In the surner'of 1979, only nine species were collected from each branch. Again, spot and Atlantic croaker were the.dominant species, (Table 3). Spot were more abundant at stations upstream of Milldam Creek in the southern branch, (Fig. 9), and upriver in the eastern and western branches. Adults as well'as juveniles were collected in the waters around Craney Island.- Adult summer flounder were also quite abundant near Craney Island. Atlantic croaker were more abundant at stations in the western and eastern branches, (Fig. 1.0). Juveniles (22-137 millimeters in total length) were found at stations below Jones Creek on the southern branch while adults (215-355 millimeters in total length) were found near the mouth of the river. Adult and very small juvenile (18-23 millimeters in total length) wea.kfish were collected from the mouth of the river to Town Point (Fig. 11). Larger juveniles were collected at upriver stations where temperatures were warmer and salinities were slightly less saline. 10 Fish Distributions in the Lower James River. Fifteen species and a total of 349 fish were collected in the lower James River during the 1978 Winter Surve.y. B.1u.eback: herring and Atlantic silversides were the dominant species (Table 4). The winter survey of 1979 yielded twenty-three species and a total of 16,405 fish were collected. Atlantic croaker was by far the most abundant species followed by, bay anchovy, Atlantic silversides and b-lueback herring. During the 1978 Winter Survey, water temperatures ranged from l..0-2.1*C while water temperatures during th&1979 Winter Survey ranged from 5.0-6.OOC. Atlantic croaker ranged in total length from 32-115 millimeters. Atlantic croaker and spot appeared*to be more abundant in waters with depths greater than 13 meters (40 feet).. On the otherhand, bay anchovy, Atlantic silversides, blueback .herring and Atlantic menhaden appeared to prefer waters with depths of less than 6 meters (20 feet). Furthermore, the Atlantic croaker, herring, and shad apneared to be more abundant on the Norfolk-side of the river, (Figs. 12 and 13). The 1978 Summer Survey yielded 18 species and a total of 2,470 fish. Striped and bay anchovies were the most abundant species foll owed by spot, weakfish and hogchokers, (Table 4Y. In the 1979 Summer Survey, 16 species and a total of 989 fish were collected (Table 5). Bay anchovy was the dominant species, althought weakfish and.several other species contributed larger, amounts to the.total biomass. Water temperatures ranged between 24-28'C in 1978 and between 21-23*C in 1979. The distributions of important species of these surveys were not plotted due to insufficient data. 12 DISCUSSION AND CONCLUSIONS The seasonal distributions of finfishes were important in considering specific-uses of the study areas; however, much of.the discussion was limited.to demersal fish (Table 6). Since only bottom trawls were utilized, the distributions and abundances of fishes such as gobies, blennies, killifish, and other finfish species of the beach zone communities and tidal creeks were not examined. Also, data were not available for large predator species such as bluefish which.avoid the net. The location and time of spawning were important in considering the distribution of fishes. Spot spawn at sea during late fall to early spring, while Atlantic croaker spawn at sea during late summer to early winter. Therefore, juvenile Atlantic croaker are found earlier in the Chesaveake. Bay than spot. Weakfish spawn during the months of May, June and July at the entrance to the Chesapeake Bay. Later, young- of-the-year migrate into the Chesapeake Bay and its tributaries. Young spot, Atlantic croaker and weakfish remain in inshore nursery grounds for a period of.a year or more before making .their first migration to sea. Alosines and striped bass migrate through the Chesapeake Bay and spawn in the freshwater reaches of the Chesapeake Bay's tributaries. Sexually mature alewife and striped bass enter the Chesapeake Bay during the month of Februarv followed approximately four weeks later by blueback herring and 13 Amer ican shaId (Hildebrand et.al., 1928). Some striped bas's are Ifound in the Chesapeake Bay and its tributaries all year.. Most youn'g- alosines leave the Chesapeake Bay upon the approach of cold weather; therefore populations of-these species that remain to overwinter are small. Small forage fish species such as bay anchovy, Atlantic silverside and naked goby which are permanent residents of the study areas spawn generally during the spring. Merriner et al. (1979) captured bay anchovy eggs, larvae and post-larvae, from late spring through early fall in ichthyoplankton samples taken around Hog Island on the James.River. Naked goby larvae and post-larvae were captured from May through,October, while silverside eggs, larvae and juveniles were captured throughout the spring and summer. In the U.S., Army Engineering Study (1977), it was suggested that the ElizabethRiver was utilized as a nursery ground by Atlantic menhaden, spot and Atlantic *croaker. In our study, winter distributions of spot and striped bass .indicated that the upper reaches of the southern branch of the Elizabeth River serve as an overwintering ground and/or nursery ground for juveniles of these species. Juvenile Atlantic croaker and alosines were captured evenly throughout the Elizabeth and lower James River. Therefore, these species utilized both river systems as an overwintering-nursery ground. Juvenile Atlantic menhaden and small forage fish species such 14 as bay anchovy and Atlantic silverside preferred the waters of the lower James River.as an overwintering nursery ground. Permanent residents of both study areas included bay anchovy, Atlantic silverside, skilletfish, oyster toadfish, blackcheek tonguefish, and hogbh6ker. White perch and yellow perch were only captured in the Great Bridge area of the southern branch of the Elizabeth River. Other finfish species that were captured were considered as incidental species; because, only a few individuals of these species were captured in trawls during a survey. During summer, the Elizabeth.River and lower James River continued to be utilized as nursery grounds for juvenile spot., Atlantic croaker.and weakfish., Juvenile spot preferred the upper reaches of these tributaries. In factf-during mid-summer juvenile*spot were found as far up the James...River as Hopewell, Virginia (approximately river mile 65). Adult spot, Atlantic croaker@and weakfish preferred the Chesapeake Bay and the lower portions of its tributaries. The Craney Island-Lamberts Point area was a popular feeding area for adult spot, Atlantic croaker and summer flounder. They were rarely captured beyond this area on the-Elizabeth River. Temperature was the major factor in the winter distribution of fishes, while the availability of food was the major factor in'the summer distribution of fishes. Principal finfish uses of the Elizabeth River and lower James River areas were (1) the nurserygrounds for juvenile spot, Atlantic croaker, 15 alewife, blueback herring, American shad, striped bass and/ weakfish; (2) the adult feeding grounds for spot, Atlantic croaker, weakfish, summer flounder, etc. and (3) the spawning grounds for important forage species such as bay anchovy and Atlantic silverside. only minor occurrences of striped bass and alosine spawning were observed in the upper reaches of the Elizabeth River.. Dredging operations in the study areas.will have a greater affect on the juvenile fishes of the nursery ground and forage fishes, than on the adult fishes of the summer feeding grounds. Adult fishes are normally more efficient in their daily search for food, and are less subject to capture by prey species than j uvenile fishes. Consequently, adult individuals will have a greater chance of finding other food resources beyond the area of a dredging project. The impact of dredging operations would be critical during winter and spring when water temperature and food availability restrict the distribution of permanent residents and,fishes of the nursery ground and during summer 'and fall whenmany larval and juvenile fishes are abundant in the study areas. Winter dredging projects may increase the frequency of winter fish kills by forcing fish to migrate into colder waters. During spring, several finfish species such as bay anchovy and Atlantic silverside spawn in the study areas. Eggs and larvae of these species may be affected by dredging operations. Other environmental factors to consider in scheduling dredge operations would be those mentioned in the Portsmouth 16 Refinery Study (1977). They include: the removal of,benthic organisms (prey for fishes); respiratory problems; and the uptake of heavy metal and/or other toxic substances. The effect of these factors on fishes would be best observed during an actual dredging operation. ACKNOWLEDGEMENTS This research was conducted at Virginia Institute of Marine Science for the Norfolk Army Corp of Engineers' Dredging Handbook Study. The authors wish to thank the graduate students.and technical staffs of the VIMS Ichthyology and Crustaceology Departments; vessel crew members; and Mr. Raymond Shackelford, owner of The Three Daughter, for their support during field studies and report preparation. We also wish to acknowledge our thanks to Ms. Mary Ann Vaden for the art work and to Ms.@Nancy Peters for typing the manuscript. 17 LITERATURE CITED Hildebrand, S. F. and W. C. Schroeder. 1928. Fishes of Chesapeake Bay. Fish Bull. 52.. T. F. H. Publications Inc. (1972 reprint) Neptune, New.Jersey. Merriner, J. V., A. D. Estes and R. K. Dias. 1979. Ichthyoplankton Entrainment Studies at VEPCO Nuclear Power Station, 1978 Final Report. VIMS, Gloucester Point, Virginia. Musick, J. A. et al. 1972. VIMS 3-C Report, (Draft) Fish Section. VIMS, Gloucester Point, Virginia (unpublished)., Nielson, B. J. and S. C. Sturm... 1978. Elizabeth River Water Quality Report VIMS Special Report in Applied Marine Science and Ocean*Engineering No. 134,.Gloucester Point, Virginia. Rooney-Char, Ann and R. P. Ayres. 1978. Offshore pipeline corridors and Landfalls in Coastal Virginia... VIMS Special Report in Applied Marine Science and ocean Engineering. No. 190. United States.Ar-my Engineering District, Norfolk, Virginia. 1977. Final Environmental Impact Statement, Hampton 'Roads Energy Company's Portsmouth Refinery and Terminalf Portsmouth, Virginia. 1.8 Table 1. Elizabeth River Winter Tra .wl Survey 1979 (22 stations in the southern branch). Species Total Number Total Weight (grams) American eel 6 850 Blueback 64 252 Alewife 79 634, American shad 5 86 Atlantic menhaden 12 66 Bay anchovy 37 35 Banded killifish 1 Striped killifish 5 Atlantic silverside 66 235 White perch, 53 Striped bass 37 1,830 Yellow perch 1 6 Spot 178 2,572 Atlantic croaker 99 57 White mullet 3 204 Naked goby 1 1 Blackcheek tonguefish 5 24 Hogchoker 60 806 7 7,717 Blue Crabs Male 27 soft). Female - (mature) 2 Female - (immature) 25 54, 19 Table 2. Elizabeth River Summer Trawl Survey 1978.(22 stations in the southern branch) Species Total,Number Total Weight (grams) American eel 9 822 Cusk eel 2 37 Atlantic menhaden 9 173 Bay anchovy 1,097 919 @Oyster toadfish 9 950 Spotted hake 8 830 White perch 11 414 Yellow perch 1 34 Weakfish 434. 2,072 Black seabass 1 30 Spot 1,860@ 18,822 Atlantic croaker 57 3,940 Naked goby 1 0.5 Butterfish 2 3 Northern searobin 1 5 Summer flounder 24 20,841 Hogchoker 386 6,676 3,912 38,568.5 Blue Crabs Male 87 Female (mature) 15 Female (,immature) 61 16 3 20 Table 3. Elizabeth River Summer Trawl Survey 1979 (3 stations. in each branch) Western Southern Eastern Branch Branch Branch Species *TN *TW TN TVI TN TW American eel 1 308 .2 150 10 950 Cusk eel 1 15 Atlantic menhaden - .2 47 Gizzard shad 1 280 Bay anchovy 47 165. 3 10 9 25 oyster toadfish 1 185 6 410 5 1F020 Weakfish 4 220" 17 100 19 277 Spot 431 4,953 160 3,230 175 1,590 Atlantic croaker 97 4,575 63 3,778 139 4,045 Summer flounder 4 .377 1 220 - - Blackcheek tonguefish .1 10 - - - - Hogchoker 50 1,380 64 1,295 18 420 636 ll:,895 317 9,208 3@8 8,654 Blue Crabs Male 16 31 37 (l soft) Female - (mature) 8 7 Female - (immature) 19 13 16 Mud crabs 35 53 60 TN Total Number TW Total Weight (grams) 21 Table 4.* Lower James River Summer (34 stations) and Winter (30 stations) Trawl. Surveys 1978.. Total Number Total Weiqhts (grams)- Species Summer Winter,. Summer Winter American eel 40 Blueback herring 150 360 Alewife 7 74 Atlantic menhaden 15 Gizzard shad 3 88 Striped anchovy 981 2,566 Bay anchovy 581 -50 279 39 Inshore lizardfish 2 7 Oyster toadfish 7 8 205 30 Skilletfish 5 Spotted hake .3 230 Striped cusk eel 18 450 Atlantic silverside 109 326 Northern pipefish .6 2 15 White perch 2 11 Black seabass- 5 234 Weakfish 256 4,891 Spot 310 7,570 Atlantic croaker 16 1. 3,007 1 Tautog 1 285 Striped blenny 5 40 Naked goby 2 1 Butterfish 17 77 .Norhern sea robin 4 35 Summer flounder '3 9 2,417 Windowpane flounder 160 Hogchoker 224 3. .4,973 150 Blackcheek tonguefish 1 1 2,470 349 27,158 1,426 22 Table 5. Lower James River Winter (30 stations) and Summer (July only; 2 stations/4 tows) Trawl Surveys 1979. Total Number Total Weight, (grams) Species Summer Winter Summer Winter American eel 3 255 Blueback herring 604 1,184 Gizzard shad 1 21 Alewife 102 896 American shad 54 790 Atlantic menhaden 116 1,816 Bay anchovy 570 5,591 1,752 3,459 Oyster toadfish 5 13 88 1,817 Skilletfish 1 13 1 45 Red hake - 1 5 Spotted hake 1 15 100 116- Striped cusk eel 12 115 Atlantic silverside 765 3,973 Northern pipefish 20 34 Black seabass .6 200 Weakfish 102 12,070 ST)ot .84 152 8,964 1,457 Atlantic croaker 92 8,.804 10,370 .11,279 Tautog 2 1,880 Feather blenny 13 100 Naked goby 9 5 Butterfish 1 10 Northern searobin 1 4 Stri-oed searobin 1 82 Smalimouth flounder @5 22 Summer flounder 13 49 2,262 3,353 Windowpane flounder 2 95 Winter flounder 1 670 Hogchoker 96 33 1,830 1,029 Blackc*heek,tonguefish 1 40 4 152 989 16,405 39,823 32,482 23 Table 6. Summary of nekton utilization of-'aquatic resources in the-Elizabeth River and lower James River. Species Blueback herring Winter nursery grounds, spring spawning probably in the upstream tidal creeks of the'Elizabeth River Alewife American shad Atlantic menhaden Probably nursery ground Bay anchovy-. Permanent resident Striped anchovy Adult and juvenile summer feeding grounds in the lower James River Oyster toadfish Permanent resident Clingfish Banded killifish Permanent resident of beach zone community Striped killifish Permanent resident of beach zone community Atlantic silverside Permanent resident Striped bass Winter nursery ground in the upper reaches of the Elizabeth River, probably some spawning in upstream tidal creeks. of the Elizabeth River 24 Table 6. (continued)- Species Weakfish Summer/fall nursery grounds,.- adult and juvenile summer, fall feeding ground at the mouth of the Elizabeth River and in the lower James River Spot Winter nursery grounds in the upper reaches of the Elizabeth River, adult and juvenile summer feeding grounds Atlantic croaker Wintbr/summ-er nursery grounds, adult summer feeding grounds at the mouth of the Elizabeth River and in the lower James River Feather blenny Permanent r esident of oyster communities Naked goby Summer flounder Adult and juvenile summer feeding grounds at the mouth of the Elizabeth River and in the lower James River Bla.ckcheek tonguefish, Permanent resident Hogchoker Permanent resident 25 Figure 1 WESrERN- BRANCH 0 EASrERN BRANCH EL IZA BE M. RI VER 1978 SURVEYS SUMMER 0 WINTER OU 5 PONCH 26 Figure 2 AA AA &Aoi A A A ELIZABErH RIVER SOUT 1979 SURVEYS 0 SUMMER A WINTER CHES JAMES RIVER 1978S A WINTER (Dec., SUMMER 00 /* CW1 JAMES RIVER 1979 s A WINTER (Dec., 04, lpo_ 29 Figure 5 CRANEY IS., LAMBERT'S POINT LOVle'r7- p.. pINNER PT- s-rfpN rowly EA Iwo A4tH z 1-5 ELIZABEM = 6-10 RIVER 0 c 11-25 z 26 - 50 CIS. ED= 51-75 T6-100 SOUTHERN 101 - 250 BRANCH A z 251 - 500 & z 501 - 750 DEEP CREEK z 751 - 1000 #00 CR- = 100 1 - 1500 A& =1501-2300 GREAT BRIDGE 144 WINTER DISTRIBUTION OF LEIOSTOMU.� XANTHURUS (spot) 30 Figtre 6 CRANEYIS. LAMBERT'S POINT LOV,-7"r pr. PINNER PT- rowiv pr E4,57RAN 8#A TTORANC" EL IZA BE rH 1-5 6-10 RIVER. JONES CR. 0 = 11-25 () = 26-50 CIS- J@ = 51-75 SOUMERIV =76-100 BRANCH A = 101 - 250 = 251 - 500 = 501 - 750 DEEPCREEK MEEK W CR. = 751 -1000 M A=1001-1500 A= 15 01- 2 300 GREAT BRIDGE WINTER DISTRIBUTION OF MORONE 36XATILIS Otriped Bass) 31 Figure 7 CRANEY IS. LAMBERT'S POINT LOVIE7r Pr. j4 49 e4, PINNER.PT- rOwjv Pr 6-10 ELIZABETH JONES CR. 11-25 RIVER 26-50 51-75 76- 100 A=' 10 1 - 2.50 251- 500 501- 750 0 DEEP CREEK 751 - 1000 #AWS CR' 100 1 - 1500 souTHEMN i9RANCH A= 1501- 2 300 GREAT xN) BRIDGE WINTER DISTRIBUTION OF MICROPOCONIAS UNDULATUS (Atlantic Croaker) 32 Figure 8 CRANEYIS. LAMBERT'S POINT Lover7. pr. 0 PINNER PT- S-rfpN 7,owfv pr FA we Nc'H 1-5 EL IZA BE M 6-10 RIVER, JONES CR. 11-25 26-50 (D =51 -T5 76-100 SOUMERN 101 - 250 BRANCH A= 251-500 501 - 750 Mrp CREEK T51 -1000 MAIMS CR- 1001 - 1500 =1501-2300 GREAT BRIDGE WINTER DISTRIBUTION OF ALOSINES (Blueback, Alewife, American Shad), 33 Figure 9 CRANEY IS. Oar% LAMBERT'S POINT 'LOVC7-7' pr. PIN Eft PT. EX STON ro*,V P7. f NCH RA 1-5 EL IZA BE M 6-10 RI VER 0 11-25 () =26-50 = 51-75 =76-100 SOUMERN BRANCH A 10, - 250 A&= 251 - 500 501 - 750 DtTP CREEK A& = 751 -1000 t0l@NS CR. = 1001 - 1500 =1501-2300 GREAT BRID SUMMER DISTRIBUTION OF LEIOSTOMUS XANTHURUS (Spot) 34 Figure 10 CRAN Y IS. LAMBERT'S POINT Los/C-I.7. PIN ER PT- SrfF?N 7'owtj Pr CA 1-5 ELIZABETH 6-10 RIVER -101VES CR. 0 = 11-25 = 26-50 = 51 -T5 = 76-100 SOWHERN BRANCH A = 101 - 250 A= 251 - 500 L = 501 - 750 DiTP CREEK 751 -1000 AOINS CR- 1001 - 1500 =1501-2300 GREAT BRIDGE SUMMER DISTRIBUTION OF MICROPOGONIAS UNDULATUS (Atlantic Croaker) 35 Figure 11 CRANEYIS. LAMBERT'S POINT LOVE-rrP j.4 PINNER PT. 70wv Pr 1-5 6-10 ELIZA BE M JONES CR. 0211-25 RI VER 26-50 51-75 OIL 76-100 101-250 -251 - 500 501 - 750 Deep. CREEK 751 -1000 MAINS CR A& 1001 - 1500 sou NCH A& =1501-2300 GREAT BRIDGE SUMMER DISTRIBUTION OF CYNOSCION* REGAL IS Weakfish /Grey Trout Figure 12. Winter Distribution of Herring, Shad, Blueback, Alewife',, Americ Hickory shad) in the Lower Jarries River. CHESA NEWPORT NEWS 00, 0 CRAN Y IS. Figure 13. WinterlDistribution of Micropogonias undulatus, Atlantic-croake Lower James River. CHESA Q Ar \% NEWPORT,. NEWS (3 A A 0 00, Elio CRAN Y IS- OYSTER AND HARD CLAM DISTRIBUTION AND ABUNDANCE IN HAMPTON ROADS AND THE LOWER JAMES RIVER by Dexter S. Haven, Reinaldo Mbrales-Alamo and Walter I. -Priest III Virginia Institute of Marine Science School of Marine Science College of William and Mary Gloucester Point, Virginia 23062 March 1981 38 Introduction Hampton Roads and the Lower James River support large populations-of oysters, Crassostrea virginica, and hard clams, Mercenaria mercenaria which are vitally important to the seafood industry as a source of seed oysters and hard clams. They are also the most vulnerable to the impacts of dredging activities because of their non-motile nature., The most critical stage in the life cycle of the oyster are the egg, larval,and setting stages where the free-swimming larvae develop, settle to the bottom and metamorphose into their adult form. The development of the egg to larvae has been shown to be affected by concentrations of suspended solids in the range of 100-200 mg/l (See the section on the effects of suspended solids in this report). 'These larvae also.need a clean hard substrate upon which to strike and metamorphose (spatfall). In order to minimize the impacts on the oyster population it is important to avoid excessive con- centrations of suspended solids and concomitant sedimentation during periods when these critical life stages are present in the estuary. Periods of, peak spatfall at selected stations in Hampton Roads.and the Lower James River are provided in Table 1 and.Figure 1. 'Adult oysters can withstand several days of elevated suspended solids levels by pumping at reduced rates or even closing their shells completely. However, rapid sedimentation in excess of .25 inch will have an adverse effect on adults and will probably kill newly settled spat. Clam larvae are less susceptible to adverse effects from increased suspended solids. In fact, they spend most of their early sedentary life, stages in the floc layer at the sediment-water interface where suspended solids levels are approximately 150 mg/l. Principal spawning times are June and early July. Table l.. Spatfall records for the Hampton Roads and lower James River (VIMS data). Spatfall on Shellstrings* Annual Summary 1976-1979 JAMES RIVER Hampton Flats Nansemond Ridge Newport News Tax Office Dates Exposed**. 1976 1977 1978 1979 1976 1977 1978 1979 1976 1977 1978 19 Tq- Jun 19-25 -- -- -- 0.0 10.0 0.0 0.0 0.0 0.0 0.0 Jun 25-Jul 2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Jul 2- 9 -- 0.0 -- 0.0 -- 0.0 0.0 Jul 9-16 0.2 1.0 0.0 0.7 -- 0.3 0.0 0.1 0.4 -- 0.0 Jul 16-23 0.3 4.0 0.0 0.0 0.1 -- 0.4 0.0 0.1 Jul 23-30 0.3 0.2 0.0 0.0 -- 0.0 -- 0.2 0.3 0.0 0.0 Jul 30-Aug 6 0.1 0.6 0.1 0.4 0.0 0.1 0.0 -- 0.2 0.7 0.0 0.0 Aug 6-13 0.3 0.8 0.0 3.6 -- 0.0 0.8 3.1 0.4 -- 0.0 0.6 Aug 13-20 0.7 0.1 7.6 0.1 0.2 3.3 1.0 0.'6 0.0 1.1 Aug 20-27 1.7 0.5 0.3 1.7 -- 1.6 0.9 0.4- 0.0 0.4 0.1 -- Aug 27-Sep 3 2.5 1.3 0.0 0.4 0.1 0.1 1.8 1.3 -- Sep 3-10 1.1 0.2 0.7 1.3 0.4 0.2 0.9 2.5 0.2 0.8 Sep 10-17 1.3 0.0 2.5 -- 0.1 0.0 0.3 9.5 0.5 0.0 0.5 Sep 17-24 4.4 2.7 1.2 0.8 1.1 0.1 0.4 -- 0.1 1.0 0.1 0.2 Sep 24-Oct 1 1 -- -- -- -- -- 0.8 1.0 -- Oct 1- 8 -- -- 1.5 0.0 0.2 Oct 8-15 TOTALS 9.7 9.2 5.2. 22.6 1.9 2.5 3.3 7.4 16.9 6.2 0.7 3.5 Shows spat per shell (smooth side only). General Guide to Setting: Dates shown are for 1979. Dates in other years Li were approximately the same. 0.1 to 1.0 spat per shell fair Not sampled in previous years. 1.1 to 10.0 spat per shell moderate 10.1 to 100 spat per shell heavy Table 1. continued (2 of 10) Brown Shoal Miles Watch House White Shoal - Dates Exposed** 1976 1977 1978 1979 1976 1977 1978 1979 1976 1977 1978 1979 Jun 19-25 -- 0.0 0.0 0.0 0.0 0.0 Jun 25-Jul 2 0.0 0.0 0.0 0.0 0.0 0.0 b.0 0-0 0.0 Jul 2- 9 -- 0.0 0.0 0.1 -- 0.0 0.0 0.1 0.0 Jul 9-16 0.9 -- 0.0 0.3 0.0 -- 0.0 0.5 0.0 0.1 0.0 0.0 Jul 16-23 0.3 0.0 0.0 0.5 0.1 0.0 0.0 0.1 0.1 -- 0.0 0.1 Jul 23-30 0.2 0.1 0.0 0.4 0.0 0.0 0.0 0.7 0.0 0.0 0.0 0.7 Jul 30-Aug 6 0.0 0.0 0.1 0.4 0.0 0.0 0.1 0.2 0.0 0. 1 0.0 1.6 Aug 6-13 0.0 0.5 0.2 0.2 0.0 0.5 0.3 0.4 0.1 3.0 0.1 2.7 Aug-13-20 0.8 0.7 0.2 2.0 0.2 0.5 0.1 2.9 1.3 0.6 0.0 2.0 Aug 20-27 0.5 0.3 0.1 0.0 0.1 0.5 0.2 0.0 0.2 6.0 0.5- Aug 27-Sep 3 0.8 0.6 0.1 0.4 0.1 0.2 -- 0.1 0.5 4.1 0.2 0.2 Sep 3-10 3.9 0.5 0.0 -0.5 0.2 1.7 0.4 0.3 0.3 O'l 0.2 0 9 Sep 10-17 '6.7 0.4 0.5 1.5 0.4 0.3 0.0 2.6 0.0 0.2 0.1 Sep 17-24 .3.2 0.5 0.7 1.3 0.6 -- 1.0 0.8 2.3 0.7 0.9 0.8 Sep 24-Oct 1 0.3 0.1 0.3 0.0 0.0 0.0 0.7 0.0 0.0 0.8 0.6 0.0 Oct 1- 8 -- - -- 0.0 -- -- 0.0 0.0 0.0 0.0 Oct 8-15 TOTALS 17.6 3.7 2.2 7.6 1.6 1.9 3.6 5.9 8.8 15.8 2.4 9.0 Wreck Shoal Warwick River Mouth Point of Shoal Date Exposed** 1976 1977 1978 1979 1976 1977 1978 1979 1976 1977 1978 1979 Jun 18-25 0.0 0.0 0.0 0.0 .0.0 0.0 Jun 25-Jul 2 0.0 0.0 0.0 0.0 0.0 -- M 0.0 0.0 Jul 2- 9 -- 0.0 0.0 0.0 0.0 0.0 0.0 -- 0.0 0.0 0.0 Jul 9-16 0.0 0.0 0.0 0.3 -- -- 0.0 0.0 0.0 0.0 0.0 0.1 Jul 16-23 0.0 0.0 0.0 -- -0.0 0.0 0.0 0.0 0.0. 0.0 0.0 0.0 Jul 23-30 0.0 0.0 0.0 0.5 0.0 0.0 0.0 0.0 0.0 0.1 0.0 0.0 Jul 30-Au'g 6 0.0 6.0 0.2 1.2 0.2 0.0 0.0 0.0 0.0 0.3 0.0 0.4 Aug 6-13 0.1 0.4 0.6 1.8 0.1 2..2 0.0 o.3 0.2 5.7 0.0 0.4 Aug 13-20 0.2 0.7 0.0 1.5 0.3 0.3 0.1 0.0 2.6 0.2 1.0 Aug 20-27 0.0 0.5 0.0 0.1 0.2 0.1 3.5 0.0 Aug 27-Sep 3 -- .1. 1 0. *1 0.2 0.0 0.2 0.1 0.0 1.6 0.3 .0.1 Sep 3-10 0.0 0.1 0.1 0.1 0.0 0.0 0.4 0.0 0.8 0.0 0.0 Sep 10-17 0.7 0.1 0.2 0.5 0.1 0.0 0.3 0.0 0.0 0.1 -- 0.'0 Sep 17-24 1.1 0.0 0.1 0.7 0 0.0 -- 0.0 0.2 0.1 0..2 0.2 Sep 24-Oct 1 O@l 0.2 0.4 0.0 0.2 0.0 0.0 0.0 0.1* 0.0 .0. 0.4@@ Oct 1- 8 0.0 0.2 -- 0.2 0 0 Oct 8-15 0.1 0.1 TOTALS 2.2 .4.1 1.9 6.9 1.1 3.0 0.9 0.3 0.5 14.9 0.9 -'2. (3 of 10) mulberry Swash Horsehead Shoal Deepwater Shoal Dates Exposed** 1976 1977 1978 1979 1976 1977 1978 1979 1976 1977 1978 1979 Jun 18-25 0.0 0.0 0.0 Jun 25-Jul 2 0.0 0.0 0.0 0.0 0.0, 0.0 0.0 -0.0 0.0 Jul 2- 9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Jul 9-16 0.0 0.0 0.0 0.6 0.0 0.0 .0.0 0.1 0.0 0.0 0.0 0.0 Jul 16-23 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Jul 23-30 0.0 0.0 0.0 0.0 -- 0.0 0.0 0.0 -- 0.0 0.0 0.0 Jul 30-Aug 6 0.0 0.2 0.0 0.6 0.0 0.0 0.0 0.6 0.0 0.0 0.4 0.5 Aug 6-13 0.0 4.0 0.1 0.7 0.3 1.1 0.1 1.4 0.0 0.6 0.0 0.3 Aug 13-20 0.1 0.0 0.4 1.2 0.1 0.5 0.0 .0.7. 0.0 0.4 0.0 0.7 Aug 20-27 0.0 1.7 0.5 0.0 2.3 0.1 0.0 0.0 1.5 0.6 0.3 Aug 27-Sep 3 0.0 2.4 0.3 0.3 0.0 0.4 0.0 0.2 0.0 0.4 0.0 0.4 Sep 3-10 0.4 0.1 1.1 0.0 0.1 0.2 0.5 0.0 .1. 1 0.2 0.4 0.4 Sep 10-17 0.2 0.0 0.7 0.1 0.7 0.1 -- 0.0 0.2 0.3 0.0@ 0.0 Sep 17-24 @0. 0 .0.1 0.4 .0.0 0.2 0.0 0.1 0.0 0.2 0.1 0.3 0.0, Sep 24-Oct 1 0.0 0.0 0.7 0.0 0.1 0.0 0.2 0.0 0.3 0.0 0.3 0.0 Oct 1- 8 -- -- 0.2 0.0 -- -- -- 0.0 -- 0.2 0.0 Oct 8-15 -- TOTALS 0.7 8.5 3.9 4.0 1.5 4.6 1.0 3.0 0.8 3.5 2.2@ 2.6 SHELLSTRING SURVEY STATIONS KINGCOPSICO POINT 4 % RAG Fn POINT JONES SHORE YEOCOMICO CORNFIELD THICKET POINT HOG 14AND GREAT NECK C 0 A RTH N O!IV@EFR.. S :i"-*; CHINCOTEAGUE DAY A- -4 " 'Vk 'Al" 'o, I POCOROKE WATTS SAY 'Ohl, N D 6 C) '0 5 BOWLERS RO K C ZTTICO 4@' MOR - - D ly.IDING C R EE K `.(ORRO11O PUNCH BOWL ONANCOCK CREEK :SMOKEY POINT WE @ST. POI! N@T BLACK STUMP POINT GOOSE P T PUNGOTEAGUE CREEK CORROTOMAN POINT IIIALLS P@. DRUM@IM@ING A@GR LIND C6 VIMS-WACHAPREAGUIE URBANNA BURTONS SAY MOSOUITO POINT C ........ PARROT'S IS. ep !DCCOHANNOCK BROAD CREEK 4@, H CREEK J. QU KOFG N MOBJACK SAY AREA LI y A NORTH RIVER SELLS ROCK M ....... ... CONJUR _!@SAWADOX C EEK I HEAD CHANNEL MACHIPO466 V 2 BLACK WATER CREEK kPOqTH :ROANE POINT 3 CEDAR POINT EAST RIVER 3 LU HOG ISLAND Y VAI;P @- 1.S.'.%',:: 1:.*-.,.:,,. _r M C11) - P B MOUT 10 J 6 9 -FOXES CREE 11 ULF OIL DOCK WARE RIVER 14 12 WILSON CREEK PAGES ROCK* CHERRYSTONE INLET OYSTER MOBJACK SAY RUNNING CHANNEL IS TOW STAKE GREEN POINT IEA MARSHES 14 BROWN'd SAY UttI, RULK it, PERRIN RIVER NEW POINT COMFORT AREA - 57@ V-4 SARAHS CREEK I PEPPER CREEK P E 8 OYER CREEK 9 MORN HARBOR DEEP WATER SHOALS 10 WINTER HARBOR HORSE @EA GREAT WICOMICO AREA a CAMERON MARSH b OFF CRANES CREEK WARWICK R. MOUTH"'' WeSTINGRAMS WRECK AND WHALEYS POINT OF SHOALS J* OFF FLEET POINT WHITE SHOAL SMILES WATCH HOUSE SW HAYNIE POINT S0 LS %,*.*'..'.-..*..;-.*..-'i']..'-.'..,- 2. rla I SHELL 13AR AND HUCNALLS ROWN H A GLESESP EOINT AND ABOVE ze HAMPTON FLATS R ID TAX PIANKABTIkNK RIVER AREA OFFICE A HOLE I% THE WALL IDGEO 8 POINT BREEZE C STUTTS CREEK POCOMOKE -SOUND AREA D THREE BRANCHES E HILLS SAY F BRAXTON RAN I SWASH (LOWER) 0 BURTONS POINT 2 SWASH UPPER) OVE POINT H ST 3 PG :0 C I APE TUNE 4 PG 3 (UPPER) Y. J PALACE BAR 5 PIS 3 (LOWER) K GINNEY POINT 6 BERNARD ISLAND L TWIGGS BRANCH 7 PG 16 8, LONG POINT M Figure 1. Locations of shellstring spatfall sample stations. 43 Table 2. Estimated of oyster-'CkAss6�trea virkinica, densities on different substrates in Baylor Survey p lic grounds in the Lower James River (Haven. Whitcomband Kendall, MS in preparation). Area Designation Est. Total No. No. Density Bushels Substrate Type Acres (bu/acre) (Millions) A-REA I (Plates 1 and 2) Oyster Rock 1812 460 0.8 33 Mud and Shell 1962 114 0.224 Sand and Shell 1690 125 0.211 Totals 5464 1.268 @AREA II (Plate 3) Oyster Rock 1348 405 0.546 Mud.and Shell 3237 78 0.252 Sand and Shell 1599 75 0.120 Totals 6184 0.918 AREA III (Plates kand 5) Oyster Rock 1171 471 0.551 Mud and Shell 2475 108 0.267 Sand and Shell 1116 108 0.120 Totals .4762 0.938 .TOTALS ALL AREAS 16,410 @.124' r4@ 18 S.ld Sh.1--d JAMES RIVER Slldl.dSh,li Sh-im. ow JAMES RIVER [email protected]'iz NO -R..d "beei, 11 @ MI. Boiler S.rd S."..d..6 S.rd..SWI I 1:1.11@lis,Nlorer- JAMES RIVER 511 .S. No pt gg/ .. ...... ... .. ............ . pp EM 0 49 or %MAE .... . ..... Shl-d @ld @yl,, Lm F.- @1- Bht Pt MY$ Pt, 1 \1 X oul X x 18 6 A, X, @' ki " bg X x X 5z". 4. JAMES RIVER BRIDGE OWER LINES (NO SU &( I o'.., R- S.M Lim JAMES RIVER __j JAMES RIVER. F-9 ........... ......... ........... . ........... . ........... . . ........... . . ........... . . ........... . . ........... . . ......... ........ . . -4, .. .. . .... ............ q2x y B.".1 Pt im "ammoofli" AF ------------ Oy- ftk sh.,l d 4.6 18 S..d pig Pt. w,w sw OW,, U,, 0 1- 0 44 The adult hard clams have a limited amount of vertical mobility and' probably will not be adversely effected by up to .5 inch of new silt. The distribution of oysters on the Baylor Public Grounds in the Lower James River are depicted in Plates 1-5. This distribution is based on the areal extent of three different substrate types, oyster rock, mud and shell and sand and shell. These are considered productive or potentially productive oyster bottoma and are where the densest populations of oysters are found (Haven, Whitcomb and Kendall, MS in preparation). The densities of oysters for each substrate type based on random sampling along transects across the river are presented in Table 2. In this tab le Area I refers to the area covered in Plates 1 and 2, Area II refers to Plate 3 and Area.III re fers to Plates 4 and 5 (Haven and Morales-Alamo, 1980). The upriver limit of the distribution of the hard clam Mercenaria mercenaria in the James River is located at the level of the James River bridge. Several intensive surveys of hard clam populations in the James River have been conducted previously by VIMS (Haven and Loesch, T972; Haven, Loesch and Whitcomb,'1973; and Haven and Kendall, 1974, 1975). The data from those studies form the basis for.this repor t on the density of hard clams' in Hampton Roads and the James River. The region between just above the James River bridge and the mouth of the river at Old Point Comfort was divided into 31 plots (Figure 2). The acreage included in each of the plots was measured with a polar planimeter on a NOAA navigation chart. Eighteen of the plots were sampled in the surveys mentioned above and the outlines of their areas are based on those data. The other thirteen plots were not sampled and their areas were delineated following the boundaries of the areas sampled and bottom depth contours. The density of clams in plots not sampled was estimated on the basis of the 45 'Warwick River JAMES RIVER .31 BRIDGE Pagop Ri ...29 2 Hampton Roads 5 30 Bridge-Tunnel NLWPUR ...NLWPUR.- 27 NEWS' 4 3 :15-A.. 23 25 22 10 10 21 8 14 20 7 19 It% Norfolk JAMES RIVER 9 13 Sampling Areas Mercenarld mercenoria Y. C ro n ey' 'I.. a", R !ver , River Figure Z. Division of lower James River into System of numbered plots used to estimate bottom acreage and standing crop of the hard clam Mercenaria mercenaria. 46 density in adjoining plots that were sampled, and our familiarity with the areas through conversations with clammers that work them and the nature of the bottom. These data are summarized in Table 3 (Haven and Morales-Alamo, 1980). 47 Table 3. Estimate of bottom acreage and densities of the hard clam, Mercenaria mercenaria, in plots surveyed between 1970 and 1974 in the Lower James River (Haven and Morales-Alamo, 1980). Source of Data Clam Density Total'No. (Footnotes) Plot No. No. Acres (Bu/Acre) (Bushels) 5 1 508 ('0.3) 152 1 2 4321 6.9 29,815 3 427 0.3) 5 128 1 4 1221 40.0 483,840 5. 1928 36.1 5 69,601 6 528 0.3) 158 2 7 5410 1.1 5,951 2 8 71 0 0 2 9 242:1 5.5 1,331 2 10. .2352 12.1 28,459 - 11 305 C 1.0) 5 305 3 12 610 11.0 .6,710 3 13 1126 0.3 338 3 14 62.0 82,026 3 15 109 6.0 654 3 16 680 65.0 44,200 3 17 183 58.0' 5 10,614 18 .1075 (25.0) 26,875 5 19 698 (25.0).5 17,450 '20 1474 (25 0) 36,850 @890 ( 5:0) 5 4,450 22 1202 ( 5.0) 5 6,010 23 2266 109.8 248X7 24 488 109.8 53,582 4 25 571 16.08 5 9,182 - 26 1486 5.0) 7,430 4 27 1473 24.12 5 359529 28 691 (25.0) 17,275 4 29 386 110.05 3P879 4 30 352 3.35 1,179 4 31 182 8.04 1,471 TOTALS 34,579 565,712 I Haven, D. S.., J. G. Loesch and J. P. Whitcomb. 1973. An investigation into commercial aspects of the hard clam fishery and development of commercial gear for the harvest of molluscs. Final Report, Contract 3-124-R with the Virginia Marine Resources Commission, for the National Marine Fisheries Service. 119 pp. Virginia Institute of Marine Science, Gloucester Point, Virginia. 2 Havenj D. and P. Kendall. 1975. A survey of commercial shellfish in'the vicinity of Newport News Point and Pig Point in the lower James River. Final Reportto McGaughy, Marshall and McMillan - Hazen and Sawyer. In: Fang, C.S. (Project Manager): Oceanographic, Water Quality and Modeling Studies 48. for the Outfall from a Proposes Nansemond Waste Water Treatment Plant, Volume 4. p. 1-28 and summary. Special Report No. 86 in Applied Marine Science and Ocean Engineering. Virginia Institute of Marine Science, Gloucester Point, Virginia. 3Haven, D. S. and J. G. Loesch. 1972. Hampton Roads corridor survey report for the Virginia Department of Highways. Final Report. 12 pp. + 6 tables. Virginia Institute of Marine Science, Gloucester Point, Virginia. 4 Haven, D. and P. Kendall. 1974. A final report to the Virginia Department of Highways on hard clam (Mer6enaria mercenaria) populations in the vicinity of the Hampton Roads Bridge-Tunnel (1-64).. 15 pp + 6-tables 4 18 figures., Virginia Institute of Marine Science, Gloucester Point, Virginia. 5Density given represents a guess-estimate based on familiarity with the area and data from surrounding areas. Bibliography Haven, D. S. and R. Morales-Alamo. 1980. Estimate of the total weight of Kepone in the major components of the molluscan fauna of the James River, Virginia. Manuscript. Virginia Institute of Marine Science, Gloucester Point, Virginia. Haven,@D. S., J. P. Whitcomb and P. C. Kendall. (MS in preparation). The present and potential productivity of the Baylor Grounds in Virginia. Phase III. Pocomoke Sound and James River. Contract No. 3-265-R-3 with the Virginia Marine Resources Commission for the National Marine Fisheries Service. Virginia Institute of Marine Science, Gloucester Point, Virginia. Spawning Activity and Nursery Utilization by Fishes in Hampton Roads and its Tributaries by Walter I. Priest, III Virginia Institute of Marine Science School of Marine Science College of William and Mary Gloucester Point, Virginia 23062 March, 1981 49 SPAWNING ACTIVITY AND NURSERY UTILIZATION BY FISHES IN HAMPTON ROADS AND ITS TRIBUTARIES The information concerning the distribution of fish eggs, larvae and spawning activity in the Hampton Roads area is very limited. The available information does, however, indicate that there is considerable spawning activity, primarily foragespecies but with some alosine and other anadromous fish in selected areas, and heavy utilization of the area by.postlarvae and juveniles as a nursery area. The report by Hedgepeth et al. (This report) outlines nekton utilization of the study area. They state that the Hampton Roads area and the Elizabeth River are nursery grounds for juvenile spot, croaker, alewife, blueback 0 herring, American shad, striped bass and weakfish. The.most abundant spawning activity was by the resident forage species, particularly anchovies and silversides. The probability of spawning by alosine fishes and striped bass in the upper reaches of'the Elizabeth River was also noted. The presence of postlarvae of spot in the lower Elizabeth River in April was noted in the Hampton Roads Energy Company EIS (COE, 1977). Table I presents-data from Olney (1978) which show the numerical and temporal distribution of fish eggs and larvae in the lower Chesapeake Bay. The occurrence of most of these eggs and larvae with the exception of the shelf spawners and tropical intruders in similar numbers and at similar times of the year in Hampton Roads proper,i's very probable. The most comprehensive study of the ichthyoplankton in the study area. is one performed in conjunction with a study of the effects of a VEPCO power plant on the Southern Branch of the Elizabeth River by Ecological Analysts, Inc. (1979). Table 2 summarizes the species taken and the life history stages present. Table 1. Species, total number and months of occurrence of fish eggs and larvae in the lower Chesapeake Bay. (Olney, 1978). Number Occurrence Species Eggs Larvae Eggs Larvae Conger oceanicus May Brevoortia tyrannus 10 28. -July-August February, April-. May, August Anchoa mitchilli 1810121 49 May-August All months.. Anchoa hepsetus* 53 May-August Anchoa spp. 6834 May-September Gobiesox strumosus 10 June-September Lophius americanus* May Urophycis regius 9 March Rissola marginata* 3 August-September Membras martin3*ca 47 March, August Atherinid larvae 132 May, August 'Syngnathus fuscus 50 All seasons Hippocampus erectus March; July-August Prionotus spp.* 14 August August Cynoscion regalis 555 June-September Menticirrhus spp. 30 June-August Leiostomus xanthurus 12 March 'Unidentified scia6nids -1248 May-August Tautoga onitis .10 May Hypsoblennius hentzi 181 June-September Ammodytes sp.* 4 January-March Gobiosoma ginsbuirgi 358 June-September 'Gobiosoma bosci 5 June-August 51 TABLE 1. (continued) Number. Occurrence Species Eggs Larvae Eggs Larvae Microgobius thalassinus 9 June-August Gobiidae, 6-spined** August Gobiidae, 7-spined 46 June-September Scomber scombrus* 3 May Peprilus triacanthus 1 July Peprilus paru 13 August Paralichthys dentatus 52 March Etropus microstomus* August Scophthalmus aquosus 10 May Pseudopleuronectes .americanus 3 March-April Trinectes maculatus 682 425 June- June-September September Symphurus plagiusa Julyr-August Symphuru type 192 June-August Sphoeroides maculatus 5 May, July, August Unknowns 89 53 Oct.-Nov., July-August Mar.-Apr. Totals 20,406 9114 SHELY SPAWNER TROPICAL INTRUDER TABLE 2. SCIENTIFIC AND COMMON NAMES, WITH LIFE STAGES AND LIVE-DEAD EGG CATEGORIES,, OF ICHTHYOPLANKTON CAPTURED IN THE SOUTHERN BRANCH STUDY AREA BETWEEN 13 FEBRUARY AND 5 SEPTEMBER 1�78. (Ecological Analysts, Inc., 1979). Scientific Name- Conufton Name Live Egg Dead Egg Ptolarvae Po6tlarvae Anguillidae freshwater eels Anguilla rostrata American eel (elver) Cupeidae herrings. Alosa spp. x Brevoortia tyrannus Atlintic menhaden x Dorosoma cepedianum gizzard shad x Engraulidae anchovies Anchoa mitchilli bay anchovy x x x x Cyprinodontidae killifishes Fundulus heteroclitus mummichog x Atherinidae silversides Menidia beryllina tidewater silverside x x x Menidia menidia Atlantic silverside x x unidentified silverside x Percichthyidae temperate bass Morone americana white perch x x x Percidae perches Etheostoma olmstedi tessellated darter x Etheostoma spp. unidentified darter x Perea flavescens yellow perch x x Sciaenidae drum Cynoscion regalis weakfish x unidentified drum x Gobiidae gobies x x Soleidae soles Trinectes maculatus hogchoker x x Unidentified x x 53 Bay anchovy eggs were the most abundant ichthyoplankton comprising 94.1% of the total catch. The postlarvae of gobies were the most abundant larvae at 3.5% of the catch. The next most abundant segment of the ichthyo- plankton was bay anchovy.larvae at 1.7%. Taken together the eggs and larvae of the bay anchovy and the goby larvae represented.99'.3% of the ichthyoplankton during the study (Ecological Analysts, Inc., 1979). During February and.March the only ichthyoplankton captured were American eel elvers and juvenile croakers. Postlarvae of the Atlantic men- haden began to appear in April.. Silversid.es and gizzard shad began spawning in early-April and.continued through July. In mid-Apri.l.white-perch and yellow perch began spawning which continued through May. The bay anchovy also began spawning in mid-April but continued through September when the study ended (Ecological Analysts, Inc., 1979). Gizzard shad and Alosa spp. preferred the upstream areas of the Southern Branch near the Great Bridge and Deep Creek locks for spawning. White perch preferred the upper rea&hes of the Southern Branch for their, spawning while' the yellow perch preferred the upper reaches of Deep Creek. During the periods of greatest abundance live and dead eggs and prolarvae of the bay anchovy were most numerous near the mouth of Deep Creek. The larvae of the Atlanticfsilverside were found only upstream of the mouth of Deep Creek and usually in low numbers.. The larvae of the tidewater silverside, however, were common at all of the.stations sampled. Goby postlarvae.were well distributed but appeared to prefer the Elizabeth River stations over those in Deep Creek (Ecological Analysts, Inc. 1979). The entire study area was used as a nu rsery area forbay anchovies, gobies, and the tidewater silverside. Yellow perch also used the entire study area as a nursery but.their numbers, were concentrated in Deep Creek and the upper-reaches of the Southern Branch. The postlarvae of the white 54 perch were restricted to the area near Great Bridge.* The post.larvae of the gizzard shad were found throughout the summer in the upper reaches of the Southern Branch and Deep Creek (Ecological Analysts, Inc. 1979).@ Literature Cited Ecological Analysts,-Inc. 1979. Portsmouth power station, aquatic monitoring studies. Final Report for Virginia Electric and Power Company, Richmond, Virginia 23261. EA Report VEP83. Olney, J. E. 1978. Planktonic fish eggs and larvae of thelower Chesapeake Bay. Unpublished Master's Thesis. College of William and Mary. VIMS, Gloucester Point, Va. 23062. 124 pp. U. S. Army Engineer District, Norfolk. 1977. Final EIS Hampton Roads Energy Company's Portsmouth Refinery and Terminal,.Portsmouth, Va. 0 0 0 0 MODEL AND PHYSICAL ENVIRONMENT 6 0 0 6 A.MODEL FOR DREDGE-INDUCED TURBIDITY by Albert Y. Kuo and Robert J. Lukens Virginia Institute of Marine Science School of Marine Science College of William and Mary Gloucester Point, Virginia 23062 March 1981 55 A MODEL FOR THE DREDGE-INDUCED TURBIDITY I. -Introduction There are two major environmental concerns on the turbidity generated by a dredging operation. One is the temporary degradation of water quality by the turbidity plume. The other is the redeposition of dredge-induced turbidity in surrounding area, thus inflicting.a negative impact on the habitat of benthic organisms. The model described in the following was formulated as a tool for quantitative estimate of these impacts. II. Theoretical Derivation The model is constructed based on the concept of Ispreading-disk' diffusion model, proposed by Frenkiel (195 3) to describe a plume from a continuous point source in uniform wind field. The diffusion in the wind direction is neglected by comparison with the advection by mean wind. U* At 7-7-z z z z As shown in the sketch, the plume is considered'as a series of thin, slices of disks one after the other. Each of the disksconsists of the material emitted from the source over I a short duration of time from t' to t'+At The disk is 56 convected to the position x=u(t-t), and has been spread in the y and z direction by diffusion during the time inter- val (t-t'). .The diffusion of sediment particles in y and z directions may be described by the equation @C/@t- W @C/@z = ky @2C/@y2 + kz @2C/@z2 (1) where C is concentration, t is time, z is the coordinate in vertical direction, y is the coordinate in transverse direction, W is particle settling velocity, k and k are diffusion coefficients in the y y z and z direction respectively. The solution of equation (1) for an instantaneous line source along x-axis is C=q/4 ky kz(t-t') exp(-(y-y')2/4ky(t-t') -{z-z'+w(t-t')}2/4kz(t-t')} (2) where q is the source in mass/length/time, y' and z' is the location of line source, t' is the time when the material is released. Equation (2) may be applied to the case of a con- tinuous point source in a uniform flow field with velocity. u in x-direction. In this case, the strength of line source 57 q becomes Q/u, where Q is the source per unit time, and Equation (2) becomes (3) III.' Application to Hydraulic Dredge A. Suspended Sediment Concentration.' in the Turbidity Plume The turbidity plume induced by hydraulic dredge may be considered as the result of a point source moving back and forth on the river bottom in the y-direction. Applying equation (3), the concentration field may be described as. (4) where x is the distance from dredge head along flow direction, z is the distance above the bottom. In this application of solution for advective diffusion equation (equation (3)), the boundary effect of the water surface is assumed negligible, because the particle settling tends to keep them away from surface layer. Since the dredge head moves back and forth in y- direction, y' is an implicit function of time, with where B is the sweeping range. At given distance x from dredge head and z above the bottom, the. dredge-induced turbidity will have a maximum at y=y', To investigate how the sediment concentration in a turbidity plume decreases with the distance from dredge head, may be normalized with its value at a reference distance . Dividing equation (5) by an d setting a given height above river bottom, it is obtained that where X = Defining the dimensionless parameters the ratio of the time required for a particle to diffuse a distance zo to the time of advection over a distance is the ratio of time required for a particle to settle a distance zo to advection time, 59 equation (8) may be written as C W exp ft,(! 1) + L-(X.-l) (7) m X 4 X ts f For a continuous dredging in a tidal estuary, a new plume is formed with each change in current direction, while the old plume is dispersed rapidly under the combine&effects of diffusion and settling. The-turbidity plume will have its maximum extent near slack tide when the current has been going in the same direction for the maximum possible time period. The reference location may be taken at the plume front, and x r equals to a tidal excursion, thus .x uT, or k /u T r r where T is one half of tidal period and u is the current speed averaged over flood tide or ebb tide. Figures 1 through 5 show the function C (X) plotted versus X for the parameter ranges encompassing typical values of coastal plain estuaries. IBecause the diffusion in current direction is assumed negligible, this model predicts that a. turbidity plume is confined within X < 1, and the sediment concentration is zero for.%X > 1. This assumption is usually valid in a tidal estuary where the advective current is much stronger than diffusion. In coastal seas where the advective currents are weak, some refinement of the model-i,s required. The figures show that C (X.) becomes less sensitive to t as the value of t increases, and becomes practically s S loses ISXP[ -1 N (xl-l)+, (X-1))] 4980 4 2000 love t d 498 200 too 40 - . . ... . ..... . ............... 20 - Ce 10 - 00f =0. 4 4 d 2 CA 0.2 0.64 0.02 t4 9 O-Se 0.05 9.1 0.2 0.3 0.4 8.61 1.62 0.04 0.1 0.2 0.4 td @j Figure 1. Normalized suspi2nded sediment distribution versus normalized longitudinal distance from dredge head, hydraulic dredge, t =0.1. s 1000 - C*.(X). IexP1-I(t'(1-1)+I (X-I))] 400 - x 4 x ta 200 t =0 d 40 20 ........................ . .. 100, 4 t =0.4 d 2 0' 4 0.1 0. 04 S-.02 G.2S r' td 9 S. Ge 9.*S 0.1 0.2 0.3 0.4 0.61 0.91 0.02 0.84 0.1 0.2 0.4 x Figure 2. Normalized suspended, sediment distribution versus normalized longitudinal distance from dredge head, hydraulic dredge, ts=0.25. lose 400 - C*. (x IXOXPE (t. +I )+I (X-1 4 x ts 200 - M t d=0 48 20 4 . ........ . ........... 100, 2 Col. t 0.4 Of d CA 0.2 Ii 94 4E 3 - t 2E-3 - . a td 0 0-02 0.05 0.1 0.2 9.3 0.4 LE 3 - 0.01 4.12 0.04 0.1 8.2 8.4 00, t .d 0 Figure 3. Normalized suspended sediment distribution versus normalized longitudinal distance from dredge head, hydraulic dredge, t =1.0. s 409 - *(X)., lox [-I (t, (1-1 )+]L (X-1 W) C. x P 4 x tu 299 - too t-d0 40 20 ................... . .... .... . 4 2 Cos ta=O. 4 9.4 0.2 9.1 0.04 0.02 4E-3 td 0 0.02 0.05 0.1 0.2 C3 0.4 1E 3 - 4.81 6.02 0.04 0.1 0.2 0.4 X t-d= Figure 4. Normalized suspended sediment distribution versus normalized longitudinal distance from dredge head, hydraulic dredge, ts=2.5., less 400 - C.* (x lexpE -1 (t', (1-1,)+, (X-I)) I x 4 x ts 200 - 180 40 - td@o 20 - is 4 -- - ----- 7-. 2 Cos, .1 =0 4 0-01 d 0.4 0.2 0.1 9.94 4E-3 2E-3 is td 0 0. 02 9.9S 0.1 8,2 0.3 9.4 IE-3 0.01 0.92 6.84 8.1 0.2 6.4 x Figure 5. Normalized suspended sediment distribution versus normal ized -longitudinal distance from dredge head, hydraulic dredge, t =10.0. s 65 independent of for . It is also seen that C*(X) varies as 1/X for and large value of B. Sediment Deposition The suspended solids in a turbidity plume will event- ually redeposit on the bottom because of p article settling.. If it is assumed that all particles deposit at the location where they strike the bottom, the deposition rate may be expressed as where D is the sediment deposition rate in mass per unit' and are the sediment con- area per unit time, centration and concentration gradient at bottom respectively, and is the. bottom elevation. Substituting equation (4), it is obtained that for the deposition due to vertical settling, and for the-deposition (or erosion) due to vertical diffusion. 66 The combination of the two mechanisms will give a negative deposition rate where which is impossible without net erosion from the bottom. For a conservative estimate of sediment deposition', the second term of upward particle diffusion is neglected and the net deposition rate, is written as To evaluate the total amount of deposition at a given location as the result of a dredging operation, the dredging operation is characterized as follows: Point of Interest dredge head .67 The previous sketch shows,that a channel of width B is to be dredged along x-direction. The dredging operation may be considered as a'series of swings by dredge head in y- direction. In each swing, the dredge head will move in 0 y-direction with a speed V and cut a slice of thickness 6 in x-direction. Since themaximum, extent of a dredge- induced turbidity plume is only the dredging within a 0 a stripe of length Zx' centered at the point of interest will contribute deposition to this location. The dredging to the left will contribute deposition when current is positive, while the dredging to the right will contribute when current is negative. To be conservative, assuming both halves of the dredging contribute deposition to the point of interest, then the total deposition per unit area is e M 2 ft D dt (9) t b 0 where t b and te are.starting and endingtime of dredging operation for the left half-of the.stripe. In case that it takes-much more than one tidal period to complete dred ging of stripe 2x the factor 2 inequation (9) may be dropped.. During each swing of dredge head, its position in Y_ @direction may be written as y B + V(t t nT) (10) b for,tb + nT < t < tb+ (n+l)T 68 where is the time required.to complete one swing In y-direction, and n is a positive integer. The distance along x-direction between dredge head and the point of interest is The time integration in equation (9) may be substituted with the sum of a series of time integration over time period , where is the number of swings required to complete dredging a distance x Substituting equations. (10) and (11) into equation (8), and substituting the results into equation (12), it is obtained that To simplify the process of estimating dredge-induced turbidity, Nakai (1978) introduced a concept of 'turbidity generation unit', which relates the turbidity to the volume 69 of dredged material. According to his-definition, the suspended sediment source may be expressed as where D is the cutting depth of dredge head. The turbidity generation unit G stands for the quantity of turbidity generated when a unit Volume of bed material is dredged under a standardized 'condition. The standardized condition was defined by the tidal current velocity at which sediment. particles with diameters larger than 74 are not resuspended. The size distribution factor is defined as where R74 is the fraction of particles with a diameter smaller than 74 and R is the fraction of particles with a diameter smaller than the diameter of a particle whose critical resuspension velocity equals the current velocity in the field. Substituting equation (14) into equation (13), and carrying out the integration, it is obtained that 70 where The equation may be written in terms of dimensionless parameters.as where and t is defined in previous section. Equation (16) is a very weak function of N for the practical range of N. A numerical test indicates that M/KGD varies no more.than 0.3% for N ranging from 1000 to 4000. Therefore, for the results presented here- after, N is taken to be 1000. The non-dimensional deposition rate is presented in graphical form from Figure 6 to 12. 0.10. 0.075 t =0.1 1.0,5,50,500 s FI/KGD 0-05- t =0.1 s 0.025- t =1.0. I T I I I I I T 0.0 2.S S.0 7.5 10.0 12.5 IS.0 17.5 29.0 Figure 6. Dimensionless sediment deposition versus normalized lateral distance from =0.1 dredge channel, hydraulic dredge, t B=0.001, Z=O. 0.2 ts=0.1 0 R/KGD 0-1 t =0. 1 0.05- s T T I T T 2.5 5.0 7.S 10.6 12.S 17.5 20.0 Figure.7. Dimensionless sediment deposition versus normalized lateral distance from dredge channel, hydraulic dredge,...t =0.005, Z=O. B 0.4 0.3 0.11, .0,5,50, 500 ts=0. 1, S R/KGD 0. 2 0.0 1 1 1 T I I I I 0.0 2.S S.0 7.S 10.0 III.S IS.-O 17.5 as.* Figure 8. Dimensionless,sediment deposition versus normalized lateral distance from MTN" dredge channel, hydraulic dredge, t =0.05, Z=O.@ B CD- 10- z Ln 2.5 4.5 6.5 8.5 10.5. 12.5 14,5 16.5 X__ Y Figure 9a. Iso-deposition contours in Y-Z plane, hydraulic dredge, t- =5, t =0.005. (The values of M/KGD.should be-multiplied by.0.501). B ............... z Ob 3.0 @4. 0 Ln y Figure 9b. z .5 2.5 4.5 6.5 8.5 Y Figure 10a. Iso-deposition contours in Y-Z plane, hydraulic dredge, ts=5@ tB=0-05. (The values of M/KGD should be multiplie,d,by 0.001). 0.5 1.0 2.0 3.0 4.0 y Figure 10b. z 4b 0.5 1.0 5 00 y Figure 10c. 4 CD to- z Ln- - ri Cp 0.5 2.5 4.5 6.5 6.5 10.5 12.5 Y Figure 11. Iso-deposition contours in Y-Z.plane, hydraulic dredge, ts=50, tB=0-005. (The values of M/KGD should be multiplied by 0.001). CD z Ln. In. 0.5 2.5 4.5 6.5 00 Y Figure 12a.. Iso-deposition contours in Y-Z plane, hydraulic dredge, ts=50, tB=0-05. (The values of M/KGD should be.multiplied by 0.001). z 0.5 1.0 1.5 2.0 2.5 .3.5 4.0 @00 Figure 12b. 82 Figures 6 to 8 show the dimensionless deposition rate on the bottom of the same elevation as dredge channel (i.e. Z=O). Figures 9 to 12 present the equi-deposition contours in Y-Z plane. Some of the contour-plots near the dredged channel are presented in enlarged form for clarity. IV. Application to Bucket Dredge A Suspended Sediment Concentration in the Turbidity Plume The turbidity plume induced by. a bucket dredge may be considered as the result of a line source stretching from water surface to bottom. The line source will move in y-direction, and then.advance x-direction as the dredge proceeds. To arrive at the concentration field, equation (3) is integrated with respect to z' from bottom to surface, The error function in equation (17) should take a negative value when its argument is negative. 83 where h is the depth of water. At given distances x from dredge location and z above the bottom, the maximum turbidity occurs at y=y1, therefore cm may be normalized with respect to the concentration at a reference distance xr. Setting z = zo, a given distance above the bottom, it is obtained that (19) where Equation (19) is presented in graphical form in Figures 13 through 21 for the non-dimensional concetration lose 401 288 t O.k,0.25,1.0,2.5,10 s t =0.1 too s -C m 7 t =10 s 4 2 0.12 8.04 1.1 6.2 8.4 x 00 X- Figure 13. Normalized suspended sediment distribution versus normalized longitudinal distance ff6m.dredge head, bucket dredge'l Z=1.0,tC 1.0. time 484 240 ts 0.1,0.25,1. 0,2.5,10 t =0. s .41 -C m 20 t =10 4 2 f 9.04 0.1 8.2 1.4 1 x CO Figure 14. Normalized suspended sediment distribution versus normalized. longitudinal distance from dredge head, bucket dredge, Z=1.0,t h=5.0. 491 ts 0.1,0.25,,l.'0,2.5,l0 298 its C 46 f =10' 4 2 T_ 9.01 0.82 0.94 6.1 9.2 9.4. x 00 Figure 15. -Normalized suspended sediment distribution. versus normalized =10. longitudinal distance.from dredge head., bucket dredge, Z*1.0, t h 411 t. =0.1 s t =0.1,0.2591.0,2.5,10 s 289 let 41 Cm ts =la@- to Z@ ZZ 4 2 0.01 0.12 0.84 0.1 0.2 O.A x 00 Figure 16 Normalized suspended sediment distribution versus normalized longitudinal distance from dredge head., bucket dredge, Z=0.5,t C1.0. lees 409 2It7 'S S -C m 44 t =1 0 S 4 2 9.91 0.62 0.84 9.1 0.2 0.4 1 x do 00 Figure 17. Normalized, suspended sediment distrihution*versus normalized. longitudinal distance from dredge head., bucket dredge, Z=0.5,t 5.0.: h t =0. I s .48 ts= 0.1,0.25,1.0,2.5,10 20 4C C m 0 s 2 1.81 1.92 8.04. 0.1 9.2 8.4 1 x 00 Figure 18. Normalized suspended sediment distribution versus normalized longitudinal distance from dredge head,:bucket-dredge, Z=1...O,t h= 10. lolls 499 ts 0.1,0.25,1.0,2.5,10 291 Is# t =0.1 s Cm 41 - 20 - if t =10 s Z-- 4 .Z 2 1.01 9.02 0.64 0.1 9.2 0.4 x Figure 19- Normalized suspended sediment distribution versus normalized longitudinal distance from dredge head, bucket dredge, Z=O,t h=1.0. 49 t 0.1,0.25,1.0,2.5,-Io. S 29 -1 C m t -0..25 -s .0, 4 S 2 1.12 0.14 -0.1 0.2 0.4 x Figure 20. Normalized suspended sediment distribution versus normalized- longitudinal.distance from dredge head, bucket dredge, Z=O,.t =5.0. h 41 t O.k,0.25,1.0,2.5,10 s C m t 0 4 .0 S t "0 2 .2,5 1.91 9.02 0.04 0.1 9.2 1.4 x @O Figure 21. Normalized suspended sediment distribution versus normalized longitudinal distance from dredge head, bucket dredge, Z=O,t =10. h 93 distributions at surface (Z= 1.0), mid-depth (Z = 0.5) and bottom (Z = 0). It is to be noted that the sediment concentration is normalized with the concentration at the plume front at the corresponding depth. Therefore the distribution curves decrease more rapidly for the surface concentration. B. Sediment Deposition As the case of hydraulic dredge, the sediment depos- ition rate may be expressed as where z1 is the bottom elevation. Substituting equation (17) and neglecting the upward diffusion, it is obtained that Unlike the hydraulic dredge in which the point source moves continuously across the channel in y-direction, the bucket dredge generates a line source which moves discretely in y-direction. To facilitate mathematical derivation, the discrete motion is approximated by a continuous motion with 94 velocity V. Then, similar to the hydraulic dredge, the total sediment deposition at a given point may be written as Substituting turbidity generation unit and carry out the integration, it is obtained that or, in terms of dimensionless parameters, where 95 Equation (23) involves three independent parameters, t t and t. Using typical values of t and t for the s h B B h dredging operation in the Elizabeth River, equation (23) is presented graphically in Figures 22 to 28 Equation (23)is- a very weak function of N, and a numerical test shows that. the value of.M/kGD changes no more than 1.2% for N varies from 200 to 2000. For the results presented in Figures 22 to 28, the, value of is taken,as 200. Figures 22, 23 and 24 show the, amount of, sediment deposition as function of distance from assuming the bottom is of the same elevation as the channel. Figures 25 to 28 present.the equi deposition contours on the Z plane. it is to be noted that-the vertical diffusive flux of sediment particles is neglected in deriving equation (23). Therefore, the amount of sediment deposition as predicted by the equation (23). Therefore, the amount of sediment desposition as predicted by a conservative estimate. 10 -F-T- t s t =0. 25 2 s 4xlO. ....................................... 2 =1 0 2xio s t '.5 5 @.L I @7. M/KGD -------------------- 72- 10 t =10 3- 4xlO 2xlO- 3- 10-3 0.1 0.2 0.4 2 4 to 20 40 100 y aN s 0 2 5 t s Figure 22. Dimensionless sediment deposition versus normalized lateral distance from dredge channel, bucket dredge, t 75.0, t =0.001, Z=O. h. B .1.0 4xlO- 1 -2xlO-1 t =0. 1 10-1 ------ t@i=o. .......... .. ............... t =1. 0 4xlO- 2- s s 2- 2xlO t =10 -2 M/KGD 10, NI 3 IN 4xlO 2xlO- 3 3 10 .4xlO-4 2xiO- 4 10-4 8.1 0.2 1 2 4. to 20 40 100 y s Figure 23. Dimensionless sediment deposition versus normalized lateral distance from dredge channel, bucket dredge, t =5.0, t =0.005, Z=O. h B 1.0 t =0. 1 0.4 - s 0.2 - ts=0. 25 .......................... ts=l. CL--.@-- 0.1 - t =2. 4xlO-2 s. 2 ts=10---- 2xlO 10-2 3 4xlO 3 M/KGD - 2xlO 10-3 4xlO-4 2xlO-4 .k 10 4xlO-5 5 WO 5 10 4xlO-6 6 2xlO - I'It 10-6 0.1 0.2 0.4 1 2 4 10 20 40 100 y 00 Figure'24. Dimensionless sediment deposition versus normalized lateral distance from dredge channel, bucket*dredge, t h=5.0, t B=0.05, Z=O. TH TS T8 S.0 5.0 O.OSO can) 0 (0 z Ln J? CD 00.5 1.5 2.5 3.5 4.5 5.5 6.5 Y Figure 25a. Iso-deposition contours in Y=Z plane, bucket dredge, t h=5.0, ts=5.0, t B= 0.05-. (The values of M/KGD. should be multiplied by 0.001). TH TS TO 5.0 S.0 0.050 C) C3 z CZ) a C@ CD 4p C) 5 1.0 1 .i5 2.0 2.5 y CD 0 Figure 25*b. TH TS TB 5.0 5.0 0.005 C;- z Ln 0 Cr) C) Q 0 8,0.5 2.5 4.5 6.5 8.5 10.5 12.5 14.5 Y C) F- Figure 26a. Iso-deposition contours in Y-Z plane, bucket dredge, t =5.0, t =5.0, t = 0.005. (The values of M/KGD.should be h s B multiplied by 0.001). T14 TS TB 5.0 S.0 0.005 CD CD C@ OD C3 z C3 kn C; CD CD C3 4-. C30. 5@ 12 3 - 4 5 6 7 8 9 y Figure 26b. TH TS TB @O 0.5 0.050 40 Z C; CD C' 0.5 2.5 4.5 6.5 8.5 Y Lj Figure 27a. Iso-deposition contours in Y-Z plane, bucket dredge, t =5.0, ts= 0.5, t = 0.05. (The value-of M/KGD should be h B multiplied by 0.001). TH TS TO 5.0 0.5 0.050 C; 0 C@ CD CD c; C) 4- Figure 27b. TH TS TB 5.0 0.5 0.005 0 Co z Ln- + CIO. 5 2.5 4.5 6.5 8.5 10.5 12.5 14.5 16.5- 19. 5 Y U1 Figure 28. Iso-deposition contours in Y-Z plane, bucket dredge, th=5.0, ts= 0.5, t B=0.005. (The values of M/KGD should be multiplied by 0.001). 106 References Frenkiel, F. N. 1953. "Turbulent Diffusion: Mean Concentration Distribution in a Flow Field of. Homogeneous'Turbulence". Advances in Applied Mechanics, Vol. 3, pp. 61-107. Kuo, A. Y. and,J. P-Jacobson. 1976. "Prediction of Pollutant Distribution in Estuaries". Proceedings of.the 15th Coastal Engineering Conference, pp. 3276-3293, Nakai,.O. 1978. "Turbidity Generated. by Dredging Projects." Proceedings of the @rd U.S.-Japan Experts' Meeting on Management.of Bottom Sediments Containing Toxic Substances. 107 Appendix 1. Suspended Solid Concentrations at the Plume Front In fig ures 1 to 5 and 13 to 21, the longitudinal distributions of suspended solid concentration are presented in dimensionless form normalized with the concentration at plume front. For Practical application, the numerical values obtained from these figures need to be multiplied by the solid concentration at the plume front to arrive at the absolute concentrations. The con- centrations at plume front-may be evaluated with equations (5) and (18) for hydraulic dredge and bucket dredge respectively. Setting x=x.:and z=z, equation (5) becomes r 0 6qCqM (x r"Z0qp exp( _42q18q0q@8qd (Al) 4 Tr 0qV_kq_kx Z r s and equation (18) becomes 4qC q(qx'fqz er:f 0qt qZ + .8q1 qm qX 0 2 h 2 4qt A h Tr k u x s erf - q(qZ-1) + (A2) 2 0qt q(21 Equations (Aq@q) and. (A2) are presented graphically in figures Al(0q4) to A4(a) with linear scales, and in figures Al(b) to A4(b) with logarithmic scales.q, Figures Al.are for hydraulic dredge, they show the v ariation of non-dimensional plume front concentration versus t with t as a parameter. Figures A2 dqf qs to A4 show the plume front concentrations at surface (6qZ=12q)q, mid. depth (0qZ2qOq.56q)an56qO`bottom (0qZ=8qO2q) respectively for. a plume induced by bucket dredge. They show the non-dime36qnsional concentrations versus t h with 32qt qs as a para meter. 1.0 .0.9 0.8 =10 0.7 J. t =2.5 0.6 C (x 'z m r o C./4TT/].,- k x z r 0.4 0.3 0, 2 .............. 3=0.25 .0.1 ..................................... .................... ......................... 0 0.2 0.4 006 0 .8 'd 0 CO Figure Al (a) @!Jorriiali z ed s--.ispended solid concentration at the front of a turbidity plume induced b,7 hydraulic dredge, linear scale. =10 l.o =2.5 t =1 s ................................... .. ............... ............I 0.2 t=0 .25 s C (x z m r 0 C)/41T,/k--k- x y z r 0.04 t =0. 1 0.02 0.01 0.01 0.02 0.04 0.1 0.2 0.4 td -Normalized suspended solid concentration.at-the front Figure Al(b). of a turbidity plume induced by hydraulic dredgef logarithmic scale. t =10 Q. 8 0.7 t =2.5, ----------------- o.6 @0. 5 t =l. 0. C x z in r'- 0 0.4 (V4hvriTk ux .4o, 0.3 t =O .25 ................................................................................. ......................... ------------ 0.1 -1 t =0.1 io 0 6 th Figure A2(a). Normalized suspended solid concentration at the front.of- a turbidity plume-induced by bucket dredge, Z"1=1.0,,linear scale. 1.0 0. 4 0.2 t .................................... ................ --=2.5 0.1 ts=1. 0 0.04 s=0. 25 m r 0 0. 02- QV 4 h Aff -kU X y r 0.03. t =0. 1 s 0. 10104 0.002 0.001 - -- r 0.01 0.02 0.04 0.1 0.2 0.4 2 4 10 t h Fi(- -A ',al 4 ZC-@j -US ,ure L@-2 (b) jqorr PC..-cd oolid Conc-tr-ticii at the f ront of a L-urjj-_JJ-J-i'--y plumc induccd by bucket dredge, Z=1.0, 1 o ga r j. thm i c scale. 1.4 t s -1.2 ----t =2. 5 s Ool 0 1.0 0.8 lo" C z0) 10, Qj4h,/7 Tkyuxr t =o.z5--.-,- -4 0.4 0.2 t =01 t 10 -4o Figure A (a) I rmaliz.ed suspended sollid concen-IC-rat-iona'C'I'le front of a turbidity plu-me induced bY bucj"I-e-'L-- U'ro-dgc,, 4"J=0.5, linear scale. in -T 4 2 0.4 C (x 'z m r 0 0,2.:.. t =10 /4hvr7Tk ux S y r t 2. 5 0.1 S tS=1. 0 0.04 ts=0. 25 0-02 t =0. 1 s 0.01 0.01. 0.02 0.04 0.1 0.2 th 0.4 1 2 4 10 Figure A3 (b) . Normalized suspended solid cuncentration at the front of a turbidity W plume induced by bucket dredge, Z-O. 5, lcr, -* @-'--4 C. scale. t =0.25 s 1.4 ts=l. 0 ts=2. 5 1.2 --.--t =10 s 1.0 s 0.8 C (x z M r 0 Q/41i/ -Tr k-yuxr 0.6 0.4 o.2 10 th Figure A4(a). Normalized suspended solid concentration-at the front of a turbidity plume induced by bucket dredge, Z=O, lincar.sciale. 10 4 2 0.4 C (X. Z- T, rp 0 U1. 2 P,14hv'Wk -ux y r t =10 s ts=2.5 0.1 t =1. 0 s 0.04 ts=0. 25 Q. 02 t =0. 1 s- 0.01 A I 0.01. 0.02 0.04 0.1 0. 2 th 0. 4 2 4 10 Figur&M(b). Normalized suspcnded solid concentration at the front of a turbiditv plume inducc6i bv bucket dredge, Z=O, logarit'limic scale. 116 Appendix 2. Applications to Example Problems Taking some typical dredging operations in the Virginia estuaries as examples, the following demonstrates how the model may be used to predict the dredge-induced turbidity and subse- quent sediment deposition. I. Hydraulic Dredge in the Elizabeth River A. Input Information (1) Specifications of dredging operation channel width B = 200 ft = 61 m. = 6.1 x 10 3 cm dredging thickness 10 ft, to be completed in two steps, each step dredges 5 ft.. D 5 ft = 1.52 m swing speed of cutter head V 0.67 ft/sec = 0.20 m/s 5 minutes cutter head cuts 6 ft in x-direction in each swing 6 = 6 ft = 1.83 m (2) Characteristics of sediments at the channel bottom mean particle size d.= 6p = 6 x 10-4 cm variance S2= 70p 2 =70 x 10- 8 CM2 the fraction of particles with diameter smaller than 74 R74 > 99.99% (3) Characterist ics of ambient flow field mean velocity u = 13 cm/sec period of flood or ebb 4 - T = 2.24 x 10 sec vertical turbulent diffusion coefficient kz 10 cm2/sec 117 lateral turbulent diffusion coefficient ky = 105 cm2/sec B. Information Sought (1) The longitudinal distribution of suspended solid concentration in the turbidity plume at 1 meter above bottom. (2) The am ount of sediment deposition in the surrounding area. C. Calculation of Model Parameters (1) settling velocity of sediment particles W = 9 x 10 3 (d 2 + s2 ) in cgs unit = 9 x 10 3 (36 x 10- 8 + 70 x 10- 8 = 10-2 cm/sec (2) particle size with critical resuspension velocity equals ambient velocity, 13 cm/sec dc = 276 p (equation of Ingersol and equation of Camp 2t (3) the fraction of particles with diameter smaller than d c R 100% (4) the particle size distribution factor k = R0/R 74 = 1.0 (5) the turbidity generation unit G = 5.3 n, 36.4 kg/m 3 for hydr aulic dredge of silty 3 clay material (Nakai, 1978) use G = 15 kg/M (6) source strength of suspended solid Q = kGD 6V = 1.0 x 15 x 1.52 x 1.83 x 0.2 = 8.34 kg/sec From the data provided by Nakai (1978), the equations may be written as: 2 Vc = 0.00128 d c . . . . . Ingersol for V c <7 cm/sec Vc = 0.783 vrdc . Camp, et al. for V c>7 cm/sec where V c and d c are in the units of cm/s and microns respectively. 118 (7) the maximum longitudinal extent of the dredge-induced plume x = uT r = 0.13 x 2.24 x 104 = 2.91 x 103 m 2 2 z x z (8) t 0 r 0 T d kz u k z 2 100 2.24 x 10 4 10 0.045 k x k (9) ts z r._ z T W2 u W2 4 2.24 x 10 0.012 4.5 (10) t B 2 // xr B 2 T B 4k u. 4k y y 3 2 (6.1 x 10 2 .24 x 104 4.15 x 10-3 4 x 10 5 D. Application of the Model (1) from figure Al(a) (or equation Al), with ts 4.5,. td= 0.045 C m - 0.9 Q/4Tr@/k_k x y z r Q C (x r"z 0.9 4,nF V_k__kx y z r Q 8.34 x 10 3 gm/sec ky 105cm2 /sec 119 2 kz = 10 cm /sec 5 xr = 2. 91 x 10 cm 6 3 Cm (xr z0 2.05 z 10 gm/cm. 2. 05 mg/l (2) Since C m(x,z OUCM (xrz0 )is nearly independent of t s for t s > 2.5, use figure 4 (or equation (7)) for evaluating Cm Cm (X,Z0)/Cm (xr z0) Cm (X,Z0 2.05,C m mg/l e.g. x X(M) C m CM(mg/1) 0.01 29.1 30 61.5 0.1 291 10 20.5 (3) With t B = 0.0042 and ts = 4.5, use figure 9 (or equation (16)) to calculate M/kGD. 3 2 kG-(2D) =1.0 x 15 x 305 4.58 x 10 mg/cm = 4.58 gm/cm 2 e.g. Z 0 Y Y(M) M/kGD M(gm/cm2 1.0 61 m 30 x 10-3 0.137 5 305 9 x 10- 3 0.041 10 610 m 3 x 10- 3 0.014 The factor 2 is introduced because the dredging operation required two cuts each with dredging thickness of 1.52 m. 120 II. Maintenance Dredge in the Hampton Roads A. Input Information (1) Specification of dredging operations channel width 4 B 800 ft 244 m 2.44 x 10 cm dredging depth D = 5 ft = 1.52 m 152 cm (a) hydraulic dredge swing speed of cutter head V 0.67 ft/sec 0.2 m/sec cutter head advance in each swing 6 6 ft 1.83 m (b) bucket dredge bucket volume V = 3 m 3 dredging frequency f = 1/120 sec. (2). Characteristics of sediments at channel bottom mean particle size -d = 6p 6 x 10 -4 cm variance s2 70 p2 70 x 10-8 cm 2 the fraction of particles with,diameter smaller than 74p R > 0.999 74 (3) Characteristics of ambient flow field mean velocity u 40'cm/sec period of flood or ebb T 2.24 x 10 4 sec vertical turbulent diffusion coefficient kZ = 10 cm 2/sec lateral turbulent diffusion coefficient 5 2 ky 10 cm sec 121 water depth 3 h 45 ft 13.7 m 1.37 x 10 cm B. Calculation of Model Parameters (1) Settling velocity of sediment particles W = 9 x 10 3 (d 2 + S2 ) in cgs unit. = 9 x 10 3 (36 x 10- 8 + 70 x 1 10-8 = 10- 2. cm/sec (2) Particle size with critical resuspension velocity equals ambient velocity, 40 cm/sec 2 2 dc = Vc /0.7831 (eq.n. of Camp et al.) = 402 /0.7832 = 2.6 x 10 3 P (3) The fraction of particles with diameter smaller than d c R 1.0 0 (4) The particle, size distribution factor k = R 0/R 74 =1.0 (5) The turbidity generation unit (a) hydraulic dredge G = 30 kg/m 3 (b) bucket dredge G = 100 kg/m 3 Note: the high values reported by Nakai (1979) are used for the sake of conservative assumption (6) Source strength of'suspended solids (a) hydraulic dredge Q = kGD6V = 1.0 x 30 x 1.52 x 1.83 x 0.2 = 16.7 kg/sec = 1.67 x 10 4 gm./sec (b) bucket dredge kGVf 1.0 x 100 x 3/120 2.5 kg/sec 122 (7) The maximum longitudinal extent of the dredge- induced plume x = uT r 4 = 0.4 x 2.24 x 10 = 8.96 x 10 3 M (8) (a) hydraulic dredge 2 z td k0 z 1002 4 / 2.24 x 10 if z M 10 0 0.045 (b) bucket dredge h2 th k- /T z (1.37 x100)2 4 10 2.24 x 10 8.45 k (9) ts Z T w2 10 /2.24 104 0.01 4.5 (10) t B2 /T B 4k y (2.44 x 10 4 2 4 4 x 10 5 -/2.24 x 10 6.65 x 10- 2 123 C. Application of the Model for Hydraulic Dredge (1) Calculate concentration at plume front. From figure Al(b) (or equation Al), with ts 4.5, t d 0.045- (i.e. 1 meter above bottom, z 1 m) 0 C M 0.9 Q/4TrVk-k x y z r Q. C (x 'z 0.9 M r 0 4 7T v"k-k x y z r Q 1.67 x 10 4 gm/sec k 105 cm 2/sec y k 10 cm2 sec z x 8.96 x 10 5 cm CM (xr'z0 1.33.x 10-6 gm/c m3 1.33 mg/l (2) Calculate near bottom (z. =lm) concentration along plume axis as function of distance from the dredge. Since C M(x,z 0UC M (xr'z0) is-nearly independent of t S for t > 2.5, use figure 4 (or equation (7)) for s evaluating C M CM CM (x,z0UC m(xr z0 CM (X,Z0 CM CM (xr'z0 1.33 C e.g. X X(m) Cm CM(mg/1) 0.01 89.6 30 40 0.1 896 10 .13.3 124 (3) With tB 0.0665 and ts 4.5, use figure 10 (or equation (16)) to calculate M/kGD kGD = 1.0 x 30 x 152 4.56 x 10 3 mg/cm 2 2 = 4.56 gm/cm e.g. 2 y Y(m) M/kGD M(gm/cm 0.5 122 67 x 10-3 0.31 1.0 244 40 xlO-3 0.18 5.0 1220 3 x 10-3 0.014 D. Application of the Model for Bucket Dredge (1) Calculate surface concentration at the plume front z 13.7 m 0 Z 1.0 from figure A2 (or equation A2), with t 4.5, t 8.45 s h m r 0) 0.75 Q/4hV7Tk yu xr with Q = 2.5 x 103 gm/sec 3 h = 1.37.x 10 cm 5 2 k 10 cm /sec y u 40 cm/sec 5 x 8.96 x 10 cm C (x z 1.02 x 10 -7 gm/cm3 0.102 mg/l m r " 0 (2) Calculate surface concentration along plume axis as function of distance from the dredge. With ts = 4.5, th 8.45, Z- 1.0. figure.17 (or eqn. (19)) is used to evaluate C m 125 C m CM (x, z 0 /8qC m (x r z0 4qCq q(qX, z 0 Cqm Cqm (xr z0 0. 102 C qm e. g. 0qx x (M) 4qC qm 4qCqm q(qmg/1) 0.01 89.6 15 1.52 0.1 896 5 0.51 0.5 4480 1.3 0.13 (3) With tB 0.0665, ts 4.5, th 8.45, use figures 26,27 (or eqn. (23)) to calculate M/kGD. kGD = 1.0 x 100 x 152 = 1.52 x 10 4 mg8q/cm 2 = 15.2 gm/cm 2 e.g. Z 0 6qy 8qY(qM) M/kGD 0qM2pm4q/cm 2 0.5 122 0.045 0.68 1.0 244 0.037 0.56 5.0 1220 0.004 0.061 126 .III. Bucket Dredge in Small Creek A. Input Information (1) Specification of dredging operations channel width B = 50 ft = 15.2 m dredging depth D = 1 m bucket volume V = 1 m3 dredging frequency f = 1/60 sec. (2) Characteristics of sediments at channel bottom mean particle size d = 6p = 6 x 10 cm variance s2 = 70p2 70 x 10-8 cm2 the fraction of particles with diameter smaller than 74p R74 > 0.999 (3) Characteristics of ambient flow field mean velocity u = 5 cm/sec period of flood or ebb T = 2.24 x 104 sec vertical turbulent diffusion coefficient kz = 2 cm2/sec lateral turbulent diffusion coefficient 4 2 ky = 10 cm /sec water depth h 1 m 100 cm 127 B. Calculation of Model Parameters (1) Settling velocity of sediment particles W = 9 X 10 3 (d2 + s 2 in cgs unit 3 8 8 = 9 x 10 (36 x 10 + 70 x 10 = 0.01 cm/sec (2) Particle size with critical resuspension velocity equals ambient velocity, Vc = 5 cm/sec dc = (V c/0.00128) 31 (eqn. of Inqersol) = (5/0.00128) = 62.5p (3) The fraction of particles with diameter smaller than d c R 0.90 0 determined from particle size analysis of bottom (4) The particle size distribution factor k R0 /R 74 0.90 (5) The turbidity generation unit G = 100 km/m 3 Note: The high value reported by Nakai (1979) is used for the sake of conservative assumption (6) Source strength of suspended solids Q = kGVf = 0.90 x 100 x 1 x 1/60 = 1.5 kg/sec (7) The maximum longitudinal extent of the.dredge- induced plume x = uT = 5 x 2.24 x 10 4 5 =.1.12 x 10 cm 1120 m 128 (8) h2 th kz /T 1002 4 2. 24 x 10 2 0.22 (9) k t z T s 2 W 2 2. 24 x 104 (0.01)2 0.9 (10) 2 B t T B 4k (1520) 2 2.24 x 104 4 4 X 10 0.0026 C. Application of the Model (1) Calculate surface concentration at the plume front z = 100 cm 0 z = 1.0 from figure A2(1?) (or equation A2), with t s = 0.9, t h = 0.22 Cm(xr z0 0.15 Q/4hy/Trkyux r C (x z 0.15 Q 4 hvfTr -ku x y r 129 with Q = 1. 5 x 10 3gm/sec h = 100 cm k = 10 4 cm2 /sec uy = 5 cm/sec x = 1.12 x 10 5 cm r Cm (xr z0 4.25 x 10-6 gm/cm 3 4.25 mg/l (2) Calculate surface concentration along plume axis as function of distance from the dredge. With = 0.22, z ='1.0, eqn. (19) is used ts = 0-9, the to evaluate m Cm Cm (X,Z 0UCm (xrz0) Cm (x,z0 Cm Cm(xr,zo) 4.25 C m e.g. X x(m) Cm Cm (mg/1) 0.01 11.2 35 149 0.1 112 10 42.5 (3) With tB = 0.0026, ts 0.9, th 0.22, equation (23) is used to calculate M/kGD kGD = 0.90 x 100 x 100 3 2 = 9 x 10 mg/cM = 9 gm/cM 2 e.g. Z 0 2 y Y(M) M/kGD M(gm/cm 0.5 7.6 3 x 10- 2 2 0.27 5 76 1.8 x 10 0.16 Suspended Sediment Experiment and Model Calibration by Christopher S. Welch, Robert J. Lukens and Albert Y. Kuo Virginia Institute of Marine Science School of Marine Science College of William and Mary Gloucester Point, Virginia 23062 March, 1981 130 Suspended Sediment Experiment and Model Calibration In order to examine the plume from a dredging operation both to calibrate the model and to characterize the plume from field data, an experiment was conducted in September 1978 in the Elizabeth River to measure the extent of the plume result- ing from hydraulic maintenance dredging of a ship channel. This experiment used a fluorometer operated as a nephelometer sampling continuously at a depth of about 1 meter from the bottom, or at mid-depth. The channel is maintained at 50 ft., with the surrounding bottom about 20 feet. The fluorometer was towed through the plume in various patterns in order to obtain the plume shape. The tracks of the tows are shown in Appendix 1 as are the associated suspended sediment data. In all cases, the tidal flow in the Elizabeth River was towards the north or the south. Also, the positions of the plume are all relative to the observed central position of the cutter head for the dredge, the source for the sediment plume. During the tests, the dredge was operating in the main channel of the reach opposite the Craney Island landfill area. The values of sus- pended sediment concentration are calculated from the measured light transmission by an empirical calibration from samples obtained during the data runs. These values are also shown in the appendix for the tracks. The set of runs encompasses most of the tidal cycle, from late flood through high slack, ebb, and low slack water. The early and full flood phases are not sampled, but in the Elizabeth River, they may be plausibly expected to be similar to their ebb counterparts. 131 The model of the plume presented elsewhere in this report (Kuo and Lukens, 1981) describes a nearly steady plume from a constant point source which is generated at the bottom of the channel and never reaches the surface. In actuality, the plume is generated by an oscillating and moving source, the cutter head of the dredge incising a notch with a cross-section of 30 ft2 for a length of 200 feet in a period of 5 minutes. The non-random currents and finite size of the cutter head are not well modeled by a point source model in some near field region, but this discrepancy is expected to be reduced rapidly outside of the immediate vicinity of the cutter head. The sweep .produces a series of diagonal intermittent plumes rather than a steady state plume. The angle. of the diagonal plume axis relative to the stream 0 lines in the case studied was less than 45 except near slack tides, so the axial model is applicable except near the source at slack water. Because the model does not consider longi- tudinal dispersionj the intermittent nature of the actual plume is not a serious drawback to model application, although experimental data showing an absence or great reduction of the plume may be expected. Finally, the along-axis section made at mid-depth (25 feet, track 2 on 9/28/78) failed to detect any suspended sediment above the ambient level (20 mg/1). Thus from a qualitative standpoint, the model is generally applicable to the generated plumes provided that the intermittent nature near the endpoints of the swings are considered in the analyses of observations. The qualitative data which do not support 132 the model description are particularly high values of sediment found near the dredge head near slack tide (9/19/80 track 3) and isolated peaks within 400 feet of the source during high currents (9/7/78 track 7). These occurrences may serve to define a near field region of about 400 feet from the dredge head, particularly near slack water, where anomalously high values of sediment may be found within the sediment plume. Apart from these exceptions, the model seems qualitatively applicable to the data. The calibration of the model starts from equation 7, repeated here for reference C * {X} = 1 e xp [-1 {t [1-1] + 1 (X-l)] (7) m X [ 4 {d [x ] t ] s A new time scale, t , is introduced as the ratio of the settling w time to the horizontal advection time for the purpose of calibration. z u t = 0 . w w x r with this definition, we have t = t 2/t , and equation (7) becomes s w/ d * C {x} = 1 e xp [-1 t {1 - 1} + 1 {x-1}] M X [ 4 d(X } 2 }] In this form, the calibration task is seen to be the determination of estimates for tw and td from measurements of concentration and distance from the source (X). To this end, it is convenient to transform equation (X.1) to the form X 1 td 2 (2) (1-X) ln (X Cm*) = 4 tw2 X-tw 133 In this form, the left hand side consists entirely of values which can be calculated from observations, and the right hand side has the form of a straight line with X intercept at 2 X= t The slope of the line is related to. t and t in the w w d same way that t is, and can be expressed as 1/4 t A s s calibration procedure which is suggested by this form is to transform the data into the left hand-side, fit a.straight line by regression to the points, and evaluate the parameters on the right hand side from the equation for the line. Before this procedure can be followed, a further scaling.is required because C M is a ratio of observed excess sediment concentration,to.a reference,value,.-chosen in the theory to be the value at the full extent of the plume. In practice, such a value can be observed only at slack tide, for the plume is fully developed only then. In addition,.the excess value of sediment concentration at that location may be below the detection threshold. These two difficulties may be overcome by defining, for the purpose of calibration, a new advective distance scale x B=axr such that thelevel of suspended sediment at x B is easily detectable. The corresponding non- dimensional scale of distance is X1 =x/x B, and the corresponding derived parameters become t d' and tw After these are deter- mined, the unprimed values are evaluated as tw =at d The equations used in evaluating the calibration datalare presented in table 1. For the particular calibration calcul ations, the tracks listed in the appendix were plotted on a common,distance scale, 134 Table 1. Equations Used in Model calibration and Interpretation for the Sediment Plume Study Formula Applied to Symbol Units General Formula Elizabeth River 3 u ft/min AH/Atxum x60 5.57xlO xAH/Atxup AH/At xr ft qr = uT xr =5903 x R xB ft chosen from data chosen from data CB mg/liter chosen from data chosen from data a 1 xB/xr xB/xr tw' 1 tw' =Xo tw'=Xo' tw 1 tw = atw' tw = atw' td' 1 td'=4mXo' td = 4mXo' td 1 td = atd' td =atd' ts 1 ts = 1/4m ts = 1/4m W cm/sec ts = 1/4m W = 1.67/twT CM* 1 CM*' = CMCB cm*' =Cm/CB kz cm2/sec kz = 1/60T zo2/td kz = 166.7/tdt X' 1 x/xB x/xB a microns a =111 w1/2 @20 C a =111 W1/2 for a sediment particle of specific gravity 2.5 135 Table 1 (Cont'd) Symbol Definitions T Period, in minutes, of rising or falling tide during observations from tide gauge or tables. .R Range, in feet, of tide rise or fall for tidal half cycle during which observations were taken from tide gauge or tables. x Distance of a given observation, in feet, from the source in the downstream direction. u Peak speed in a given locality for mean tide as p given by Cerco and Kuo (unpublished ms.). u Mean speed over tidal.phase during which observations were obtained. Um Mean speed over a mean tidal phase. C A maximum measured value of sediment concentration m in an approximately transverse section of the plume. X10 The horizontal-intercept of the line fitted to the, data., m The slope of the straight line fitted to the data. xB The base distance, in feet, chosen from the data to represent the advective extent of the easily detectable part of the plume. C The sediment concentration, in mg/liter, inferred B or measured at xB' z0 Height, in meters, of the observations over the bottom. a Diameter of a representative sediment grain. AH Difference in height from high to low (or low to high) tide in feet. At Time-span, in minutes, between successive tidal height extrema. Table 2. Plume Axis Estimates for Calibration Day Track Maximum Background Distance Concentration Value from Source X1 C XI M -ln (XIC C X, m m 9/7/78 1 27 260 27 9/7/78 2 46 26 200 20 9/7/78 3 103 (27) 50 76 9/7/78 4 51 30 200 21 9/7/78 5 30 25 200 5 9/7/78 6 73 35 220 .22 38 -.246 1.90 9/7/78 7 90 27 320 .32 63 +.004 3.15 9/7/78 8 80 24 440 .44 56 +.164 2.80 9/7/78 8 69 24 460 .46 45 +.029 2.25 9/7/78 9 60 33 870 .87 27 +1.076 1.35 9/7/78 10 44 34 1130 1.13 10 +4.963 0.50 9/7/78 11 44 34 1230 1.23 10 +2.600 9/19/78 1 86 17 115 .575 69 1.41 4.93 9/19/78 1 73 17 160 .800 56 4.65 4.00 9/19/78 1 31 17 220 .1.100 14 -1.05 1.00 9/19/78 2 114 38 110 .22 76 -.309 1.52 9/19/78 2 114 38 160 .32 76 -.339 1.52 9/19/78 2 121 38 360 .72 83 +.459 1.66 9/19/78 2 46 38 680 1.36 8 +5.76 0.16 Table 2 (Cont'd) Day Track Maximum Background Distance XI C XI Concentration Value from Source m i---xfln(XIC M. Cm 9/19/78 3 181 24 60 .300 157 +0.520 11.21 no 3 49 24 130 25 -3.50 1.79 parabola 3 38 24 200 1.00 14 -0.189 1.00 9/19/78 5 65 22 60 - 43 - 9/26/78 2(1) 40 9 230 .575 31 1.209 4.25 9/26/78 2(1) 22 9 360 .90 13 3.449 1.63 9/26/78 2(1) 18 9 390 .975 9 3.779 1.13 9/26/78 2(11) 40 9 230 .288 31 -0.417 1.24 9/26/78 2(11) 37 9 700 .875 26 -0.660 1.04 9/26/78 2(11) 32 9 880 1.100 23 -0.131 0.92 9/28/78 No clear interpretation Table 3. Calibration Calculated Values Date 9/7/78 9/7/78 9/19/78 9/19/78 9/19/78 9/26/78 9/26/78 Plume 1 2 1 2 3 1 1 Tidal Phase late flood full ebb early ebb late ebb late ebb low slack low slack T 384 375 379 379 379 365 365 R 2.8 -2.6 3.3 3.3 3.3 -2.0 -2.0 AH 7. 3 x 10-3 -6.9 x 10- 3 -8.7 x 10 -3 8.7 x 10- 3 _8.7 x 10- 3 _5.5 x 10 -3 5.5 x 10 -3 At x 16549 -15276 -19480 -19480 -19480 -11806 -11806 r x13 Failed -1000 200 500 200 -400 -800 CB 20 14 50 14 8 25 a .065 .0103 .0257 .0103 .0339 .0678 xv .340 Failed .355 Failed .383 Failed M 2.6-4.7 4.15 6.6 tw .583 .596 .619 t .038 .015. .021 w t 3.5-6.4 5.89 10.11 d td .230-.415 .151 .343 t .0035-.0063 .0015 .0013 S W .117 .293 .217 CO a .3 8 60 52 k 1.08-1.95 2.90 1.36 z 139 based on linear interpolation between listed positions. Values of sediment concentrations for plume peaks and background were then obtained from these graphs. These-values are given in table 2. The peak concentration values were Plotted versus @distance and an "eyeball" line was used to estimate the general' Shape of the plume. A value for the referencedistance (x B) and, concentration (C were then read from the line. These B values were used to compute the relevant model parameters with results shown.in table 3. In this table, the notation "failed" indicates those cases for which the correlation of the points from the data was clearly low or the.line sloped downwards 0 instead of.upwards. Interpretation of the calibration-results consists of examining the reasons for the "failed" data and comparing particle sizes and vertical diffusivities corresponding to the ...model parameters chosen to other published values. The earliest data set for which the calibration failed was the first plume on 9/7/78. In this instance, the three estimates of C at a m single distance, 200 feet, prevented the analysis from being stable, so the failure can be assigned to sampling strategy rather than properties of the plume. The data for plumes 1 and 3 on 9/19/78 also failed. In the first case, the corre- lation was low. As in all but one of the failed cases, the plume was not found further than 250 feet from the source, be- cause it had already dispersed, because the survey did not happen to cross it, or because the dredge operation was not .140 producing a detectable plume at the time of sampling or during the preceeding 20 minutes. Plume numbers of 9/19/78 also failed, and this is of particular interest because it pro- duced the highest measured suspended sediment concentrations (>180 mg/liter) for the entire study. Such large maxima were never found far from the dredge head, and near thehead the. operation.must appear as a distributed source rather than the point source assumed.in the model formulation. Thus, we can estimate that the near field region, for which the point source theory is not expected to describe the plume extends about 300 feet from the dredge head. The final failure concerns the second interpretation of the data from 9/26/78. If we choose the first interpretation, which fits the data, there are two unexplained peaks of sediment concentration'downstream from the dredge head, at distances of 700 and 880 feet from the head.. These peaks could be attributed to earlier dredging at a different source strength or to extraneous sources, such as the passage of vessels down the channel. Particle diameter (a) and coefficient of vertical diffusivity (k are related to the non-dimensional times used z in the analysis, t and t respectively through formulas w d' listed in Table 1. Some insight into the effectiveness of the model and its calibration can be gained by comparing the calibration-derived values of particle diameter and vertical diffusivity to other estimates from other studies. The particle diameters obtained from the calibration analyses ranged between 38 and 60 microns. These sizes are 141 in accordance with the "type B" sediments of Nichols (1972), who. noted that sediments in the James River of type B were found in the lower estuary both on the shoals and on the channel floor, where tidal current peaks reached 30 cm/$ec. .Because the tidal currents in the lower Elizabeth River near the bottom reach 30 cm/sec and because the Elizabeth River is directly connected to the main channel of the lower James River, the model results appear to be consistent with the previous work. On the other hand,,samples takenfrom the general area subsequent to the dredging have a meandiameter 2 of only 6 microns, with a variance of 70 microns- The dis- crepancy between these numbers could be ascribed to any or a combination of several sources, -i.ncluding 4 substantial varia-@-- bility of the*sediments within that reach of the river, differences in laboratory techniques used in the various size measurements and the response of the model calibration procedure to a heterogeneous mix of sediment sizes. Values of the coefficient of vertical diffusivity, where such a formulation is used to depict vertical transfer of material in a fluid with turbulent fluctuations, range over a wide range of values. Kullenberg (1971), measuring the vertical and horizontal growth of dye patches in a shallow part of the Kategat, reported values of k z ranging, from .05 to 11.0 cm2/sec. The values were strongl y relat ed to the degree of vertical stratification in the water column, higherstrati- fications inhibiting the vertical mixing., In the James River, 142 Pritchard (1967) estimated values of kz which ranged from 0 at the surface and bottom, due to the analysis method, to a 2 pair of peak values of 5 and 9 cm /sec. At a distance of. 11 meter from the bottom, the value is slightly greater than 2@ .1 cm. /sec. In view of the wide range of values:found in the Kategat, the range of values found in the calibrationstudy, 2 1.08 to 2.90 am /sec, appears-t agree well with the available previous data. With these results, the model, which before had been, shown to be in accord with the field data in@ a qualitative sense outside of a near field region of about 300 feet, seems to give results in the process of calibration which are quanti- tatively.consistent with other studies in thestudy area. This agreement serves as a verification of themodel formulation. 143 REFERENCES kullenberg, G., 1971, Vertical diffusion in shallow waters, Tellus XXIII, pp. 129-135. Kuo, A. J. and R. L. Lukens, 1981. A Model for the Dredge- Induced Turbidity, Virginia Institute Of Marine Science, 1981. Nichols, M. M., 1972, Sediments of the James River Estuaryf Virginia, The Geological Society of America Memoir/331 43 pp. Pritchard, b. W., 1967, observations of circulation in coastal plain estuaries in.Lauff, ed., Estuarje,s, Publication No. 83, American Association for the Advancement of Science, pp. 37-44. 144 Appendix 1 SUSPENDED SEDIMENT DATA Position Data, Date-Track Time Location(ft) Time Relative* Tidal NIS E/W to High(H) or' Low(L) Water 9/7/78-1 1032.-40 -95S 0 + A : 53 Late 1034.81 -150S 0 H 1:29 Flood 1039.31 -200S 0 1042.60 -250S 0 1045.52 -300S 0 1047.67 -350S 0 9/7/78-2 1202.50 -200S 400E H 0:00 High 1211.00 -200S -450W. Slack 9/7/78-3 1215.70 -50S 260E H 0:12 High 1217.11 -50S 0 Slack 1219.21 -50S -25OW 9/7/78-4 1233.67 -80S 0 H + 0:30 High 1240.18 -1000S 0 Slack 9/7/78-5 1306.70 -40S 0 H + 1:04 High 1308.83 -400S 0 L - 5:11 Slack. 9/7/.78-6. 1607.16 220N -80W H + 4:04 1607.90 220N 0 L 2:11 Full 1608.62 220N 200E Ebb 9/7/78-7 1608.62 220N 200E 1611.51 40ON -30OW 40 .9/7/78-8 1611.51 40ON -30OW 1613.71 420N .-80W 1615.22 50ON 300E 9/7/78-9 50ON- 300E 1618.70 110ON -10OW 9/7/78-10 1618.70 110ON -10OW H 4:16 1620.90 130ON 300E L 1:59 9/19/78-1 1303.87 0 0 H 2:14 1304.20 10ON 0 L 4:03 Early 1305.96 30ON 0 Ebb 1306.52 50ON 0 1307.20 70ON 1307.78 90ON 0 40 145 Appendix 1 Position Data (Cont'd) Date-Track Time Location(ft) Time Relative Tidal NIS E/W to High(H) or Phase Low(L) Water 9/19/78-2 1540.35 0 0 H + 4:51 1541.22 20ON 0 L 1:26 Late 1542.11 40ON 0 Ebb 1543.00 60ON 0 1543.83 80ON 0 1545.01 990N 0 9/19/78-3 1552.01 100ON 0 H + 5:03 Late 1553.79 800N. 0 L 1:15 Ebb 1554.82 60ON 0 1555.97 40ON 0 1556.92 20ON 0. 1558.81 50N 0 1559.02 0 0 9/19./78-4 1607.20 -200S 0 H + 6:17 Late 1608.14 0 0 L 1:00 Ebb 1608.89 20ON 0 9/19/78-5 1609.60 20ON 0 H + 6:20 Late 1611.22 0 0 L - 0:58 Ebb 1612.34 -200S 0 9/26/78-1 1042.01 100ON 0 L + 0:13 Low 1044:21 80ON 0 6:03 Slack 1046.40 60ON 0 1047.90 40ON 0 1050.17 20ON 0 1050.93 0 0 1052.05 -200S 0 .9/28/78-1 1144.60 80ON 0 H + 5: 33 Low 1148.21 60ON 0 L 0:29 Slack 1152.10 40ON 0 1155.25 20ON 0 1158.01 0 0 1200.81 -200S 0 1203.52 -400S _0 9/26/78-2 .1104.02 0 0 L + 0:35 Low 1104.72 20ON 0 H 5:47 Slack 1106.82 40ON 0 1108.01 60ON 0 1109.60 80ON 0 1111.24 100ON 0 146 Appendix 1 Position Data (Cont'd) D.ate-Track Time Location(ft) Time Relative Tidal NIS E/W to High(H) or Phase Low(L) water 9/2.6/78-3 1749.11 100ON 0 H + 0:58 High 1750.30 80ON 0 L 5:27 Slack 1751.82 60ON 0 1753.11 40ON 0 1755.13 20ON 0 1756.40 0 0 1757.80 -200S 0 1758.90 -40os 0 1800.00 -600S 0 1801.63 -800S 0 9/28/78-2 1210.80 -400S 0 H 5:59' Low 25 ft. 1212.29 -200S 0 L 0:06 Slack 1213.86 0 0 1215.68 20ON 0 1217.05 40ON 0 1218.69. 60ON 0 1219.97 80ON 0 .9/28/78-3 1226.60 80ON -20OW 1229.01 80ON +200E 9/28/78-4 1231.13 60ON- 200E, 1238.31 60ON -20OW 9/128/78-5 1303.10 40ON -20OW 1305.13 40.0N 200E 9/28/78-6 1306.66 20ON 300E 1316.00 20ON -30OW 9/2,8/78-7 1320.80 20ON -30OW 25 ft. 1324.11 200N. 300E 9/28/78-8 1327.57 60ON 300E L + 1:11 25 ft. 1335.40 60ON -30OW H - 5:02 9/28/78-9 1736.50 20ON 0 L.+ 5:20 Late 1739.55 -200S 0 H 0:53 Flood 1740.75 -400S 0 40 Suginded Sediment Data 9 78 Track I Depth is 50 feet Time Sed.Conc Location (ft) Time Sed.Conc Location (ft) Time Sad-Conc Location (ft) EST mg/t M/S E/W EST mg/l N/S E/W EST mg/l N/S E/W 1032.49 32 -95 S e 1033.42 36 1034.46 31 1032.42 32 1033.4S 37 1034.49 31 1032.45 31 1033.49 37 1034.52@ 38 1032.48 30 1033.51 38 1034.54 30 1032.51 30. 1033.54 38 1034.S7 30 1932.54 30 1033.56 39 le34.61 30 1032.56 30 1033.59 38 A032.59 29 1033.61 38 1034.64 30 1034-67 30 1932-62 29 1033.64 38 1034 69 30 1032.64 29 1033.67 '39 le34:72 30 1*32.67 29 1033.69 39 1034.74 30 1932.69 28 1033.72 39 1034 77 31 1032.72 28 1033.75 40 1034:81 31 -150 5 0 1032.75 as 1033.77 40 1034.83 31 1032.77. 27 1033 81 40 1034.86 32 1032.81 27 1033:83 40 1034.89 32 1032.84 28 1033.86 38 1034.91 32 1032.86 28 1033.89 38 1034.94 32 1032.99 30 1033.91 36 1034.96 33 1932.91 31 1033.94 36 1034.99 33 1932.94 32 1033.96 35 le3S.e2 33 1032.96 34 1033.99 34 1035.04 33 1032.99 3S 1034.01 33 le35.07 33 1033.01 36 1034.04 32 1035.10 33 1033-04 38 1034.07 32 1935.14 33 1033-06 38 1034.09 32 1035.17 32 1033.09 39 1034.12 32 1035.19 32 1033.11 49 1034.14 32 1035.22 31 1033.14 40 le34.17 32 193S.24 31 1033.17 40 1034.19 32 1035.27 39 1033-21 39 1034.23 32 1035.29 29 1033.24 38 1034.26 .32 1035.32 28 1033.27 38 1034.29 32 1035.34 28 1033-29 37 1034.31 31 1035.37 28 1033.32 37 1034.34 31 103S.41 27 1933.34 36 1034.38 31 103S.44 27 1033.37 36 1034.41 31 1035.46 27 1033.39 36 1034..43 31 iS35.49 26 Su3pended Sediment Data 9/7/78 Track I (continued) Depth i3 SO feet TI-me Sed.Conc Location (ft) Time Sed.Coac Location (ft) Time Sed.Conc Location (ft) EST mg/l t4/S E/Y EST mg/l M/s E/W EST mg/l h/S E/W. 1035.51 26 1036.49 35 1037.41 47 1035-54 26 1036.52 36 1037.51 47 1035.56 26 1036.54 37 1.037.53 47 1035.59 25 1036.S7 37 1037.56 47 1835.61 25 1036.60 38 1037.61 47 1035.64 24 1036-63 38 1037.64 47 1035.66 24 1036.66 37 1037.66 47 1035.69 24 te36.68 37 1037.69 47 1035.72 24 1036.71 37 1037.71 47 1035.74 23 1036.74 37 1037.74 47 1035.77 23 W36.77 38 1037.76 46 1035.79 23 1036.79 39 1037.79 46 1035.92 23 1036.82 41 1037.82 46 1935.84 23 1036.84 43 1037.86 46 1035.87 23 1036.87 45 .1037.89 45 103S.89 23 1036.89 46 1037.91 45 1035.92 24 1036.92 46 1037.94 44 1935.94 as 1036.94 46 1037.97 43 193S.97 26 1036.97 46 1037.99 42 1935.99 27 1036.99 45 1038.02 41 1036.62 28 1037.02 44 1038.04 49 1036.04 31 1037.04 43 1038.07 38 1936.07 33 -1037.07 43 108.99 37 1036.09 34 1037.09 43 1038.12 36 1036.12 36 1037.12 43 1938.14 35 1936.14 38 le37.14 44 1038.17 34 1936.17 39 1037.17 45 1038.19 33 1036.19 39 1937.19 46 1038.22 32 1036.22. 39 1937.22 46 1938.24 32 1036.25 38 1037-24 47 1038.29 32 1036.27 38 1037.27 47 1038.31 33 1936.30 37 1037.29 47 1038-34 34 1936.32 36 1037.32 47 1038-36 3S 1036.35 35 1037-34, 47 1038.39 36 1036.37 34 1037.37 46 @1038.41 37 1936-40 34 1937.39 46 1038.44 38 1036.44 34 1937.42 46 1038.46 39 1936.46 34 1037.45 47 1938.49 39 OD Su3rnded Sediment Data 97.,78 Track I (continued) Depth t3 50 feet Time Sed.Conc Location (ft) Time Sed.Conc Location (ft) Time Sed.Conc Location (ft) EST Mg/l hIs E/U EST Mg/ t N/S E/W EST mg/t hIs E/U .1038.51 40 1039.61 44 1049.79 51 1038.54 40 -1039.63 4S, 1040.81 Sl 1838.56 40 1939i66 4S 1040.84 st 1038.59 40 1039.69 45 @1040.86 51 1038.61 40 1939.73 45 1040.89 51 1038.64 40 1939.76 45 1049.92 51 1038.67 40 1039.79 4S 1040.94 51 1038.69 40 1039.82 4S 1049.97 52 1038.72 41 1039.96 44 1040.99 52 ISM.76 41 1039.89 44 1041-06 52 1938.78 41 1939.92 43 1041.99 st 1039.81 41 1039.96 42 1041.12 -SI 103B.84 41 1039.99 42 1041.15 51 1038-87 41 1040.01 41 1041.18 51 1038.90 41 1049.04 41 1041.21 51 1038.92 41 1049.07 41 1041.24 Sl 1038.9S 41 1040.19 40 1041.26 51 1038.99 41 1040.14 40 1041.29 sl 1939.01 41 1040.18 40 1041.33 51 1639.GS 40 1040.21 410 1941.37 52 1039.08 49 1040.23 41 1041.39 S2 1039.11 40 1940.26 41 1041.42 S2 1039.13 41 1049.88 41 1041.45 sa 1039.16 41 1940.31 41 .1041.47 sa 1939.19 41 1940.33 42 1041.50 S2 1939.22 42 1940.37 42 L941.S2 S2 1039.25 42 1040.49 43 1941.SG 51 1939.29 42 1040.43 44 1041.S8 Sl 1939.31 42 -260 S a 1040.46 46 1041.61 st 1039.34 .42 1040.49 47 1041.63 51 1939.37 42 1040.52 48 1041.67 51 1039.39 43' 1040.54 49 1041.70 51 L939.42 43 1049.57 so 1041.73 51 1939 4S' 43 1040.60 50 1041.76 S2, 1039:49 44 1040.66 so 1041.78 S2 1039.52 44 le49.69. So 1041.81 S3 1039.56 44 1040.73 SO 1941-.84 53 1039.58 44 1040.76 so 1041.97 S2 Suvended Sediment Data gN8 Track I (continued) Depth is SO feet Tim Sed.Conc Location (ft) Time Sed.Conc Location (ft) Time Sed.Conc Location (ft) EST 09/1 H/S E/U EST Mtg/ t M/S E/W EST 09/1 H/S E/U 1041.90 sl 1042.92 52 1944.11 46 1041.92 so 1042.94. 52 1044.14 46 1041.95 48 1042.99 sl 1044.17 46 1041.97 47 1943.01 Sl 1044.19 46 1042." 46 1043.04 51 1044.22 4S 1042.03 44 1043.07 51 1044.2S 45 1"2.86 43 1043.14 so 1044.27 4S 1"2498 42 1043.17 51 1044.32 4S 1042.11 41 1043.20 51 1044.34 4s 1"2.13 40 1043.23 52 1044.37 .44 1"2.17 40 1943.27 52 1044.39 44 1"2.19 41 1943.31 53 1044.42 44 1"2.22 41 1043.34 53 1044.44 43 IOQ.24 42 1943.37 -53 1944.51 42 1"2-27 43 1043.41 52 1044.54 41 IGQ.29 43 1043.44 51 1044.56 40 1042.33 44 1043.46 St 1944.59 40 1042.36 44 1043.49 50 1044.62 39 1"2.39 43 1043.51 .59 1044.64 38 1"2.41 43 1043.54 49 1044.67 37 164P.44 43 1043.S7 48 1044.70 37 IOQ. 47 43 1043 61 48 1044.74 36 164aAg. 43 1043:64 48 1044.77 35 1042.52 44 1043.67 47 1044.84 34 1042.SS 45 1043.71 .47 1044.87 34 1042.57 46 1043.74 47 1044.89 34 1842.60 49 -2SO S 9 1043.79 47 1044. 92 34 1042.62 so 1843.82 47 1044.9S 33 1942.6S 53 la43.84 47 1044.99 33 1942.68 54 1043..87 47 104S.02 33 1042.71 55 1043.89 47 1045.04 33 1642.73 ss 1043 92 47 1045.07 33 1042.16 SS 1943:95 47 104S.11 33 1042.79, 55. 1043.98 47 1045.13 33 1042.82. S4 1044.01 46 164S.17 33 1942.84 S4 1044.94 46 104S.21 .33 1042.87 53 1044.96 46 104S.24 33 1042.89 53 1044.09 46 1045.39 33 C) Suarnded Sediment Data 97/78 Trac-k I (continued) Depth is 59 feet Tim Sed.Conc Location (ft) Time Sed.Conc Location (ft) Time Sed.Conc Location (ft) EST mg/l M/S E/W EST mg/l M/S E/IJ EST mg/t M/S E/W 1945.36 33 [email protected] 40 104S.39 33 1046.56 40 1045.42 33 1046.59 39 1045.46 33 1046.62 39 1045.49 33 1946.66 39 1M.S2 33 -390 S 0 1046.69 39 1045.55 33 1046.72 39 .164S.S7 33 1046.75 A 104S.61 34 1046.79 39 104S.64 34 IM 82 38 1045.67 35 i8466:sr. 38 1045.71 36 1046.89 38 1045.73 37 1046.92 39 .104S.78 38 le46.95 39 104S.81 38 le46.99 39 104S.83 39 1047.01 39 1645.98 39 1047.04 30 1945.91 49 1047.07 40 1645.94 40 1047.10 40 194S.97. 40 1047.12 40 1046.00 4e 1047.17 39 1046.02 40 1047.22 39 1946.06 41 1047.25 39 1946.09 41 1047.31 39 1046.12 42 1947.34 39 1046.15 42 1047.37 39 1046.19 43 1047.41 38 1046-23 44 1047 43 38 1-046.26 44 1947:51 38 1046.28 4S 1947.53 39 1046.31 4S 1947.56 39 IW-34 AS 1047.59 39 10".37 44 1047.62 39 10". 39 43 1047-64 39 1046.42 43 1047@67 39 -3S9 S 0 1046.44 42 -1046.47 41 1046.49 41 @-n Suspended Sediment Data 9/7/78 Track 2 Depth is 50 feet Time Sed.Conc Location (ft) Time Sed.Conc Location (ft) Time Sed.Conc Location (ft) EST mg/l M/S E/U EST mg/l N/S E/U EST Mg/l N/S E/W 1202.50 29 -200 S 4" E 1203.49 30 1204.52 29 1282.50 29 1203.52 29 1204.55 29 1282.53 28 1203.55 28 1294.S7 29 t262.57 28 1203-57 as 1204.60 29 1202-57 28 1203-60 27 1204.62 29 1292.59 28 1203.G3 27 1204.67 29 1292.62 28 1203.65 27 1204.76 29 1202.65 28 12e3.68 27 1204.73 29 1202.68 28 1203-72 27 1204.76 29 IM.69 28 1203.7S 27 1204.80 29 1202.71 28 1203.78 27 1284.82 29 1202'.75 28 1203.82 28 1204.8S--,' 28 1202.77 28 1203.85 29 1204.87 28 1292.80 28 1203.88 29 1204.88 28 1202.82 28 1203-91 28 1204-91 29 .1202i85 27 1203.93 28 1204-93 29 1202.87 27 1203.95 .27 1204.95 29 1292.90 27 1203.98 27 1204.97 29 1202.93 27 1204.02 27 1205.00 29 12e2.96 27 1204.02 27 1205.02 29 1203.99 28 1204.05 27 1205.95 29 1263.03 27 1204-08 28 1205.07 29 1203.06 27 1204.12 29 1205.97 29 1203.08 27 1204.15 30 1205.10 28 L203.12 28 1204.16 39 120S.12 28 1203.15 28 1204.11 30 120S.16 as 1203A8 28 1204.20 39 im 18 28 1293.22 29 1204-22 29 12OS:20 28 1293.2S 29 1204-23 29 120S.22 28 .1203.27 29 12e4.25 29 IN5.24 28 la*3.30 -29 1204.27 29 laes.25 28 t003.34 29 1204.30 29 120S.27 28 t293.37 28 1204.3S 29 120S.30 28 1293.38- 28 1204-37 29 120S.33 1203.39 28, 1204.40 29 1205.36 as IM3.42 29 1204.42 29 .120S.49 29 1203.45 30 1204.46. 29 1295.43 29 1203.47 39 1294.48 29 1205.48 29 Suspended Sediment Data 9/7/78 -Track 2 (continuac Depth is Se feet Time Sed.Conc Location (ft) Time Sed.Conc Location (ft) Time Sed.Conc Location (ft) EST mg/l H/S E/U EST mg/l H/S E/W EST N/S E/U 124S.52 29 1206.73 39 1207.71 41 1295.S6 30 1206.76 39 1207.75 40 I M AS 30 1206.78 39 l2e?.78 40 1205.62 30 1206.82 38 1207.80 40 1295.64 30 1206.85 37 1207.83 "39 .1 M @67 30 1206.87 35 1297.8S 37 12N.70 3e 1206.89 34 1207.85 37 IM.74 30 1206.92 35 1207.86 37 1265.77 30 1206.96 36 1207.88 38 129S.80 30 1206.99 34 1207.92 .40 1205.84 30 1207.02 31 1207.92 40 IM.85 30 1297.04 39 1207.94 39 120S.87 39 1207.07 30 1207.97 37 1205.87 39 1207.08 29 1207.99 35 IM.90 30 1207.10 29 1208.00 35 1265.93 30 1207.13 30 1208.02 35 1205.97 39 1207.16 29 1208.05 35 1206.02 31 1207.20 29 .1208-05 35 1206.95 31 1207.22 30 1208.07 35 12". 10 31 12e7.23 39 12e8.99 36 1206.13 31 1297.26-, 30 1208.12 37 1206.17 31 1207.27 30 1208.19 37 1206.20 31 1207.29 39 1288.13 37 1206.22 31 1297.32 31 1208.15 37 12".25 31 1297-33 31 1298.16 35 12".es 31 1207.35 32 1.298.17 35 12W.30 31 1207.37 32 1298.17 3S 12W.34 32 1207.38 32 1298.21 39 1296.37 31 1207.40 32 1203.24 44 1206-39 31 1207AS 33 -1209.27 46 1286.43 39 1207.50 35 1296.47 31 1297.54 36 1208-30 46 1208.30 46 1206.St 32 1207.57 38 1208.33 43 1206.5s. 33 1207.60 39 1208.35 39 1206.59 36 1207.62 40 1208.37 -39 1206.62 -37 1207.64 40 1208.38 39 1206.66 37 1207.67 41 1208.39 39 1296.70 38 1207-.-68 41 :1298-42 40 Susmded Sediment Data 97/78 Track 2 (continued) Depth- is So fact Tim SAW.Conc Location (ft) Time Sed.Conc Location (ft): Time Sed.Conc Location (ft) EST mg/l N/S UW EST mg/t H/S E/U EST mg/l N/S E/U IM.44 38 1209.28 33 1219.13 31 1M.47 38 1209.32 34 1210.14 31 I M .48 38 1209.33 34 1210.17 31 lm@sl 38 1209.35 34 1210.20 31 1208.54 40 1209.37 33 1210.22 30 1298.57 4S 1209.40 32 1210.23 30 1298.60 46 1289.42 32 1210.25 30 ROOM 46 1209.42, 32 1219.27 30 I M .63 44 1209.46 33 1210-28 is IM.65 44 1209.48 34- 1210.30 29 12M.66 44 1209.50 34 1210.32 27 IM.69 44 .1209.51 34 1210.35 26 12N. 72 42 1299.52 34 121e.37 25 I M .74 40 1209.55 34 1210.40 26 1298.77 36 1209.57 34 1210..42 27 1208.79 34 1299.58 35 1210.43 27 1298.82 32 1209.60 35 1219.47 27 1298.84 3e 1299.62 34 1210.49 27 1208.85 29 1299.62 34 12le-50 27 1298.87 29 1209.65 34 1210.S3 .27 1208-90 29 1209-67 34 1210.57 30 1208.93 22 1209.68 34 1210.60 35 -1208.97 36 1209.71 32 1210.63 37 1M.97 39 1209-73 29 1210.63 3? 1209." 39 1209.77 26 1210.65 36 1209.02 38 1209.79 2S 121e.68 34 1209.67 36 1209.82 27 1210.69 34 IM 09 31 1209.85 29 1210.71 34 IM:10 31 1209.88 39 1210 74 35 1209.11 32 12eg.92 32 12 10: 76 35 .1299.13 32 1269.95 33 1210.77 35 IMOIS 31 1209.97 34 1219.80 34 12". is 31 1299.98 34 1210.82 33. 12". to 31 1210.92 35 1210.85 32 t2*9 20 31 1210.eS 37 1219.87 31 IM:21 31 1210.06 36 1219.99 32 la". 22 31 1210.08 33 1210-92 32 12". as 32 1210.11 32 1210.93 32. Suspended Sediment Data 9/7/78 Track 2 (continued) Depth is So feet Time Sed.Coac Location (ft) Time Sed.Conc Location (ft) Time Sod-Cone Location (ft) EST mg/l H/S E/U EST mg/l H/S E/U EST mg/l M/S E/U 1210.95 31 1210.95 30 1210.98 as 1211.00 26 -209 S -450 U Suspended Sediment Data 9/7/78 Track 3 'Depth is 50 feet Time Sed.Conc Location (ft) Time Sed.Conc Location (ft) Time Sed.Conc Location (ft) EST Mg/t hIS E/W EST mg/l N/S E/W EST Mg/t H/S E/W 1215.70 83 -50 S 260 E 1216.53 72 1217.32 69 121S.74 99 1216.57- 74 1217.34 71 1215.76 100 1216.58 74 IR17.36 74 121S.77 100 1216.60 75 1217.37 74 1215.79 100 1216.62 81 1217.40 72 121S.92 102 1216.63 81 1217.40 68 L21S.82 103 1216.65 82 1217.42 63 121S.84 103 1216.67 81 1217.44 61 1215.85 102 1216.70 78 1217.45 61 121S.88 99 1216.73 71 1217.49 63 12is.ge go 1216.7S 76 1217.51 64 1215.93 87 1216.77 76 1217.52 63 121S.94 84 1216.78 77 1217.5S 60 121S.9S 84 1216.82 81 1217.57 58 121S.98 88 1216.83 83 1217.S8 58 12M.62 go 1216.85 83 1217.61 so 1216.05 89 1216.88 84 1217.63 so 1216.97 84 1216 88 83 1217.64 60 1216.10 76 1216:92 W 1217.67 59 1216.12 69 1216.94 75 1217.70 57 1216.14 67 1216.97 73 1217.73 53 1216.15 66 1216.98 72 1217.74 S3 1216.18 63 1217.00 13 1217.76 56 1216..20 60 1217.02 73 1217.89 62 1216.22 58 1217.03 72 1217.83 67 1216-23 59 1217.OS 68 1217.87 68 1216.26 63 1217.07 65 1217.90 68 1216.27 63 1217.08 68 1217.99 69 1216-29 62 1217.11 .9e -50 S 0 1217.93 69 1216-32 61 1217.12 93 1217.97 72 1216-35 64 1217.14 95 1217.98 ?3 1'216.38 66 1217-18 98 1218.00 73 1216.40 67. 1217-21 191 1218.02 69 1216.41 66 1217.23 97 1218.05 68- 1216.44'.. 66 1217-23 96 1218.07 St 1216.44 66 1217.26 go 1218.141 56 1216.47 67 1217-28 Be 1218.12 54 1216.50 ?9 1217-31 70 1218.13 53 Ul Su3pondid Sediment Data. 9/7/78 Track 3 (continued) Depth 13 SO feet Time Sod-Cone Location (ft) Time sed.Conc Location (ft) Time Sed.Conc Location (ft) EST 09/1 NIS EST og/l NIS E/U EST mg/t NIS E/W 1218.15 S3 1219.98 31 1218.19 53 1219.10 31, 1218.20 52 1219.13 39 1218.23 S2 1219-14 30 1218.26 53 1219-16 30 1218.29 53 1219.18 30 1218.32 53 1219.21 30 -50 S -250 U 1218.34 S2 1218.37 53 1218.40 53 1218.42 52 1218.43 51 1218.47 21 1218.59 37 1218.S3 37 1218.55 36 lals.sa 36 1218-62 37 1218.65 38 1218.68 40 1218.79 41 1218.71 39 1219.73 37 1218.77 35 1219.79 34 1218.81 34 1218.93 34 IP18.25 33 .1218.98 33 1218.99 33 1218-93 32 1218.95 32 1219.98 32 1219.99 32 1219.9B 32 l2L9.:03 32 1219.0s 32 1219.96 32 Su3panded-Sedivent Data. 9/7/78 Track 4 Depth is 50 feet Timm Sed.Conc Location (ft) Time SeCConc Location (ft) Time Sed.Conc Location (ft) EST -mg/ I N/S E/U EST mg/l M/S E/u EST mg/l N/S l/U 1233.67 36 -80 S 1234.75 44 123S.84 35 IZ33.70 36 1234.75 44 3S 1233.74 3S 1234.79 42 1235.91 35 1233.77 35 1234.82 41 1235.95 35 1233.82 3S 1234.8S 40 -.1235.98 34 1233.85 36 1234.89 39 1236.02 34 1233.97 37 1234.92 39 .1236.05 34 1233.90 38 1234.95 38 1236.08 34 1233.93 39 1234.97 38 1236.12 34 1233.96 40 1234.98 .38 1236. 15 34 1233.99 41 1235.01 39 1236.19 34 1234.91 41. 1235-02 38 @1236.22 34 1234.04 43 1235.04 38 1236.25 3S 1234.08 44 1235.97 36 1236.27 3S 1234.10 44 1235.10 35 4236-30 35 .1234.13, 4S 123S.13 34 1236.32. 3S t234.16 47 123S * 17 34 1236.34 35 1234.18 48 1235olg 34 1236.37 35 L234.49 48 1235.22 36 1236.40 35 1234.21 47 1235.24 37 1236.45 34 1234.25 46 -123S.25 37 -1236.48 34 1234.28 47 123S.27 37 1236.52 33 .1234.30 48 1235.30 37 1236.SG 33 1234.33 49 123S.34 37 1236.60 33 1234.3S so- 1235.37 37 1236.63 33 1234.38 Sl 123S.42 37 -1236.6S 32 1234.41 51 123S.45 37 1236.68 32 1234 43 '51 1235.49 36 1236.70 33 1234:44 --Sl 123S.52 36 1236.7S 33 1234.47 so 1235.SS 36 1236 78 33 1234.50 SO 1235.60 36 1236:81 33 1234.53 49 123S.62 36 1236.84 33 -1234.56 49 1235.67 36 1236.86 33 1234.59' 48 L235.70 36 .1236.82 33 1234.63 47 123S.74 3S 1236.90. 33 1234.67 4S 1235.77 3S 1236.94 34 -1234.79 44 123S.89 3S 1236.9S 34 1234.72 -44 123S.82 3S 1236.98 33 SuIrAded Sediment Data 9-7/78 Track 4 (continued)' Do th 13 SO foot p Time Sed.Coftc Location (ft) Time Sed.Conc Location (ft) Time Sed-Conc Location (ft) EST mg/t H/S E/u EST mg/l N/5 E/W EST 0g/l H/S E/u IZ37-01 33 1238.28 31 1239.S@ 32 1237.05 34 1239.31 31 1239.52 32 1237.06 34 1238.35 31 1239.55 33. L237.10 33 1238.38 .31 1239.5S 33 1237.13 33 1238.41 31 1239.59 33 1237.16 33 1238.46 31 1239.62 33 1237A9 33 1238.49 31 1239.65 33 1237.21 33 1238-52 31 1239.69 33 1237.23 33 1238-5S 31 1239.73 33 1237.26 32 1238.59 31 1239.77 33 1237.30 32 1238-62 31 1239.78 33 1237.33 32 1238.66 31 1239.82 33 -1237-36 32 1238.69 31 1239.85 33 1237.39 31 1238-71 31 1239.88 33 1237.41 31 1238.74 31 1239.92 32 -1237.43 31 1238.77 31 1239.96 32 1237.46 31 1238-80 39 1239.99 32 1237.51 31 1238.83 30 1240.02 32 1237.5S 31 1238.87 30 1240.OS 32 1237.59 31 1238.90 39 1248.88 32 1237.63 31 1238.94 30 1240.11 32 1237.66 31 1238.98 39 1240.15 32 1237-69 31 1239.02 30 1249.18 32 1237.73 31 1239-GS 29 1237.77 31 1239-09 29 1237-80 31 1239-14 29 1237-83 30 1239.17 29 1237.87 30 1239.19 30 31 1239.22 30 1237.96 31- 1239.24 31 la37.99 39 .1239.28 31 1238.92 30 1239-31 31 1239.64 30 1239.34 31 1238.48. 31 1239-35 31 1238.11 31 1239-38 31 1238-15 39 1239.41 31 1238-19 30 1239.45 31 1238-24 31 1239-50 31 i-n Suarnded Sediment Data 9 7/78 Track 5 Depth is 50 feet Tine Sed.Conc Location (ft) Time Sed.Conc Location (ft) Time Sed.Conc Location (ft) EST mg/l N/S E/W EST mg/t N/S E/W EST mg/ I K/S E/U 1306.79 25 -40 S e 1307.83 26 1306.73 25 1307 86 26 1396.76 25 1307:89 26 1306.79 26 1397.92 26 1306.92 26 1307.96 26 1306.86 26 1397.99 26 1306.89 26 1308-03 26 1396.93 26 1308.9S 26 1306.96 26 1308.06 26 1306.99 26 1308-09 26 1367.02 26 1308-12 26 1397.06 26 1308-IS 26 1307.10 26 1308-18 2S 1397.13 26 1308.21 25 .1307.17 as 1308-24 25 1307.21 26 1308.2S 25 1397.24 26 1308.27 .25 1397.27 25 1308-30 25 1387.30 25 1308-33 24 1397.33 2S 1308.37 24 1307.36 26 1308.41 2S 1307.36 26 1308.44 24 1307.40 26 1398.'46 24 1307.45 26 1308.47 24 1307.48 , P.6 1309.SO- 23 138?.Sl 26 1308-53 23 1307.SS 26 1398-58 23 1307.56 26 1398-62 23 1301.58 2G 1308.65 23 1307o6l 27 1398.70 24 1-397.64 28 1308.73 24 1367.67 29 1308.7S 2S 1307.69 29 1308-76 2S 1307.71. 29- 1308-89 as 1307.74 as 1308-83 25 -409 S 0 1307.76 23 1397.79 27 1307.80 27 C) Suspended Sediment Data 9/7/78 Track 6 Depth is So feet Time Sed.Coac Location (ft) Time Sed.Cont Location (ft) Time Sod-Cone Location (ft) EST mg/l NIS E/W EST mg/l HIS E/U EST mg/ I NIS E,/W 1607.16 64 220 -89 w 1607.87 62 1607.19 73 1607.88 64 1607.19 73 1607.99 54 229 N 9. 1607.22 64 1607.93 42 1697.26 46 1607.95 38 1697.27 45 1607.96 39 1607.28 46 1607.99 37 1697.39 46 1608.01 36 1607.32 49 1608.93 37 160?.34 S3 1698.03 37 1607.35 52 1698.06 41 169?.35 51 1699.07 42 1607.37 53 1698.98 42 1607.38 51 1608.10 40 1607.40 49 IS98.11 39 1697.43 4S ISOBA3 39 1607.46 S3 1608.15 38 1691.47 55 1608.19 34 1697.49 48 1608.29 34 160?.Sl 42 1698-22 34 1607.52 43 1608-25 37 1607.SS 43 1698.25 38 1697.se 49 1608.27 37 1607.S8 39 1608.39 37 1697.60 42 1698.30 37- 1607.63 48 1698.33 36 1607.63 48 1608.34 3S 1607.66 47 1608.36 49 1697.67 45 1609.39 41 1607.?0 38 1698.41 41 .1607-73 47 1698.42. 41 1607.75 51. 1698.45 51 1607-75 S2 1698.47 6S 1697.77. sa 1698-51 65 L667.78 51 1698.S4 61 1607.81 48 ISMS? 5a 1607.82 48 1608-59 47 1607-84 55 1608.62 46 220 N 2" E SU3pended Sediment.Data 9/7/78 Track 7 Depth i3 SO feet Time Sed.Conc Location (ft) Time Sed.Cont Location (ft) Time Sed.Conc Location (ft) EST "/I N/S. E/U EST Mg/l H/S E/W EST mg/l M/S E/U 1698.62 46 220 N 2" E 1609.30 53 160.96 78 1608.62 46 1609.33 51 1609.98 77 1608. 64 44 1609.36 47 16te.01 78 1608.65 46 1609-37 47 1610.03 so 1688.67 so 1609.39 48 1610A4 82 1698.67 53 1609.40 49 1610405 85 1608.70 55 1609.42 so 1610.06 87 1608.70 56 1609.44 54 1610AS 86 1608.72 S6 1609.47 57 1610.10 94 1608.75 S2 1609.47 ..57 1610.11 84 1608.75 47 1609.49 S9 1610.12 85 1608.77 44 1689.49 59 16MIS 87 1608.78 42 1609.52 sl 1610.17 90 1608.80 42 1609.55 47 1610.18 84 1608-82 44 1609.55 47 Iste.19 7? 44 1609.57 53 1610.20 70 1608.87 40 1609.S8 54 1619.22 63 1608.98 40 1609.S9 60 1610.24 64 1608.99 44 1609-69 64 1610.26 65 1688.92 45 1699-61 66 1610.27 65 1608.92 45 1609.64 67 1610.30 62 1698.95 46 1609.67 66 1610.31 62 1608.96 46 1609.69 63 1610.33 63 L698.98 45 1609.79 66 1610.34 64 1689.00 43 1609.72 71 1610.37 58 1609.02 43 1699.75 77 1610.40 52 1609.04 49 1609.77 79 1610.41 54 1699.05 51 1609-80 76 1619.42 64 1609.07 49 1609.81 76 1610.44 68 1609.10 47 1609.83 so 1619.45 72 1699.12 48 1609.86 at 1610.47 66 1609.14 sl 1609.86 82 1618.49 61 1699.0 Sl 1609.88 82 1610.50 60 1609.ZO SE 1699.89 79 1619.53 52 1699.23 st 1669.90 76 1619.53 SO 1609.2S se 1609.93 76 1610.56 4S 1609.27 Sz 1609.94 78 1610.58 4z 1609.28 -S2 1699.9s 78 1610.60 40 Suspended Sediment Data 9/7/78 Track 7 (continued) Depth is 50 feet Time Sed.Conc Location (ft) Time Sed.Conc Location (ft) Time Sed.Cont Location (ft) EST mg/t M/S E/IJ EST mg/l N/S EAW EST mg/t H/S E/U t6le.60 40 1611.28 36 1619.60 41 1611.31 32 1619.61 39 1611.34 27 1610.63 39 1611.36 26 1-610.64 39 1611.38 26 1610.66 41 1611.39 28 1610.66 41 1611.42 29 1610.69 42 1611.45 28 M9.71 43 1611.48 28 1610.72 43 1611.49 27 1610.74 4S 1611.51 26 409 N -300 U 1610.76 141 1619.77 112 1619.78 81 1610.79 12S 1619.80 136 1619.82 104 1610.85 so 1610.88 39 1619.89 as 1610.91 28 1619.93 43 1619.94 44 1619.96 44 1610.98 43 1619.99 42 .1611.99 41 1611.92 41 161-1.05 40 1611.06 39 1611.10 .36 1611.13 31 1611.14 30. 1611.16 P9 1611.18 29 1611.21 1611-25 32 1611-28 3S S113pended Sediment Data 9/7/78 Track 8 lcontinued) -Depth is 59 feet Time Sed.Conc Location (ft) Time -Sed.Conc Location (ft) Time Sed-Conc Location (ft) EST 00/1 H/s E/U EST mg/l N/s E/li EST mg/l N/S E/U 1614.11 65 1614.94 37 1614.11 64 1614.95 37 1614.14 69 1614.96 39 1614.14 69 1614.99 40 1614.17 65 1615.02 40 1614.18 59 1615.04 41 1614.29 S7 1615.05 41 1614.24 53 1615.08 40 1614.24 so 1615.11 38 1614.27 so 161S.15 3S so 1615.18 38 1614.39 46 1615.22 42 50e h UO E 1614.30 45 1614.33 43 - 1614.34 43 1614.37 42 1614.38 43 1614.40 43 1614.42 40 1614.43 40 1614.47 41 1614.51 49 1614.54 37 1614.57 38 1614.58. 38 1614.61 37 1614.6S 38 1614.66 38 1614.68 38 1614.72 37 .1614.75 36 1614.76 37 1614.78 49 1614.?g. 49 1614.82 41 1614.8S 40 1614.88 39 1614.91 36 Z_ Suarnded Sediment Data 97/78 Track 8 Depth i3 59 feet Time Sed.Conc Location (ft) Tifee Sod-Cone Location (ft) Time Sed.Conc Location (ft) EST 09/1 M/S E/IJ EST mg/l H/S E/U EST I N/S E/U 1611.Sl 26 400 N -300 U 1612.46 29 1613.35 47 1611.54 26 1612.48 30 1613.36 45 1611.56 31 1612.59 28 1613.39 46 1611.58 31 1612.53 25 1613.40 48 1611.60 28 1612.57 24 1613.49 48 1611.61 27 1612.59 as 1613.42 46 1611.63 29 1612.62 M 1613.44 49 MloGg 27 1S12.64 28 1613.46 51 1611-69 a 1612.67 30 16,13, .47 48 161-1.70 28 1612.69 28 1613.49 48 1611.73 31 1612.71 32 1 13.sa 49 1611.77 28 1612.73 38 13-53 51 1611-80 as 1612.76 36 1613.54 54 1611.83 25 1612.79 40 1613.S7 57 1611.85 27 1612.82 36 1613.57 57 1611.89 29 1612.8S 37 1613.60 S3 1611-99 31 1612.88 35 1613.60 53 1611-93 -31 1612-88 34 1613.63 ss 1611.97 29 1612.92 36 1613.65 ss 1611-98 -29 1612.9S 40 1612.01 31 1613-67 56 1612.9s 41 1613.71 67 420 H -99.U 1612.05 32 1612.98 37 1613.74 75 1612.96 33 1613-99 36 '1613.76 81 1612.99 29 1613.02 38 1613.77 89 1612.12 25 1613.04 41 1613.89 _76 1612.16 as 16-13.05 48 1613.83 70' 1612.18 25 1613.97 so 1613.96 64 1612.29 27 1613.19 41 1613.90 54 1612.23 28 1613.12 41 1613.92 sa 1612.27 26 44 1613-94 53 1612.28 25 -1613.14 49. 1613.97 SS 1612.31 as 1613-18 Sl 1613.97 :Ss 1612-33 28 IS13.Pl Sl 1614.". 53 1612-33. 29 1613.24 47 1614.01 S2 1612.37 26 1613-2S 48 mcw s4 1612.39 27 1613.27 so 1614.9S SS 1612.42 -30 1613.30 50 1614.06 67 1612.44 29 1613.32 47 1614.07 68 C3,% Sus nded Sediment Data M/78 Track 9 Depth x3 50 feet Time Sed.Conc Location (ft) Time Sed.Conc Location (ft) Time Sed.Conc Location (ft) EST mg/t H/S E/W EST. 09/1 N/S E/U EST mg/l N/S E/W 1615.22 42 SW 300 E 1616-19 4e 1617.01 47 1615.22 43 1616-23 39 1617.9'2 47 1615.26 41 1616.26 37 1617.04 sl 1615.27 40 1616.29 36 1617.07 SS 161S.29 @1616.31 36 1617.99 SR. .16LS.33 37 1616.32 36 1617.11 59 161S.33 36 1616.35 37 1617.13 S7 161S.37 36 1616.35 38 1617.15 ss 161S.40 38 1616.39 41 1617.17 SR 161S.40 38 1616.42 42 1617.29 S9 161S.42 .38 1616.42 41 16M22 -S9 161S.4S 38 1616.45 40 1617.22 69 161S.46 37 1616.46 49 1617.2s S4 161S.SO 37 1616.48 .41 1617.28 48 .161S.S3 3S 1616.49 41 1617.31 4S 161S.SS 34 1616.54 42 1617.32 46 1161S.S7 34 1616.S7 40 1617.3S 47 lsls.s9 34 11616.s7 41 1617.36 so- 161S.90 34 1616.66 40 1617.41 AS 161S.62 3S t616.60 41 1617AS 42 161S.65 37 1616.63 46 1617.48 39 161S.67 37 1616.93@ 47 M7.49 39 16tS.68 38 1616.6S 46 1617-S2 .39 161S.70 38 1616.79 4S 1617.SS 41 161S.73 38 1616.72 45 1617.S7 4S 1615.77 38 1616.74 4S 1617.58 46 16tS.81 37 1616.77 44 1617.68 46 161SAS 37 1616.78 43 1617.63 43 MS.88 36 1616.89 44 1617.6S 44 161S.91 35 1616-83 45 A617.67 46 161S.95 3S 1616.87 48 1617.70 44 1616.01 3S 1616.87 SO 1617.73 40 1616.01 36 .1616.89 48 1617-75 39 1616.OS 36 1616-93 49 1617.77 41 1616.19' 35 1616.94 410 1617.80 43 1616.11 3S 1616.96 47 16M82 46 1616.13 36 t616.98 47 M7.8s -48 1616.16 38 MO." -47 50 ON ON Suspended Sediment Data 9/7/78 Track 9 (continued) Dept-h is 50 feet Tim Sed.Conc Location (ft) Time Sed-Conc Location*(ft) Time Sed.Conc Location (ft) EST ag/t N/S. E/U EST Mg/l N/S E/U EST mg/t N/S E/U 1617.94 54 1617.97 51 1618.90 47 1618.04 43 1618 99 43 1618:11 4S 1618.11 45 1618.13 46 1618.18 4S 1618.22 4S 1618.24 4S- 1618.25 45 .1618.27 44 1618.39 46 1618.33 46 1618.37 44 16LB.41 44 M8.45 46 1618.50 46 1618.53 45 1618.53 44 1618. A 4S 1618-S7 46 1618.69 45 1612.63 43 1618.63 42 1618.67 42 IGLB.70 43 1189 N -100 U Suarrided Sediment Data 97, 78 Track 10 Depth i3 So feet Tiine Sed.Conc Location (ft) Time Sed.Conc Location (ft) Time Sed.Conc Location (ft) EST mg/l NIS E/AJ EST mg/l NIS E/ld EST UgIj NIS E/U 1619.70 43 1190 H -190 U 1619.70 41 1620.73 41 1619.74 40 1619.75 41 1620.75 42 1618.7S 40 1619.78 42 1620.77 42 1618.78 40 .1619.80 43 1620.80 39 1618.82 40 1619.8S 41 16ae.92 41 1618.86 41 1619.87 39 1620.84 42 1618.87 41 160.90 39 1620.87 43 1618.89 39 1619.93 40 1629.88 44 1618.92 37 1619.9S 40 16210.90 40 1300 M 390 E 1618.94 35 1619.98 39 1618,97 35 1620.eS 37 1618.99 35 1620.02 37 1619.00 39 162G.9S 37 1619.02 41 1620.08 38 1619.03 43 1620.10 39 1619.OS 44 1620.11 39 1619.08 4S 1620.13 39 1619.12 41 1620.17 42 .1619.14 41 1620.17 43 1619.15 41 162e.19 43 .1619.19 42 1620.22 43 1619.22 42 162e.22 43 1619.25 41 1620.25 44 1619.28 40 1620.27 44 1619-33 41 1620.28 45 1.619-37 43 1629.32 44 1619.40 42 1629.33 44 1619.45 49 1629.37 42 1619.48 39 1629.49 42 1619.48 39 1620.43 1619.52 42 IG20.47 37 1619.52- 42 1620.50 37 1619.55 41 1620.ss 36 1619.S8. 41 1629.57 36 1619.62 49 .1620.69 36 1619.63 39 1620.63. 36 1619.6s 49 1620.66 38 1619.67 41 1620-68 3.9 00 Suspended Sediment Data 9/19/73. Track I Depth is 50 feet Tim Sed.Conc Location (ft) Time Sod-Cone Location (ft) Time Sed.Conc Location (ft) EST Mg/l H/S E/W EST ag/t N/S E/U EST mg/l M/S E/U. 1303.87 27 9 0 1305.16 is 1304.62 .29 1305.20 is 1364.05 31 1305.24 17 1304.08 36 1395.96 16 3" N a 1304.18 , 41 1306.S2 17 see " a 1304.14 45 1307.29 16 790 N @e 1304.16 49 1307.78 14 gee N 0 13".29 48 IGO M 0 1304.23 59 1304.aS 82 1304.28 86 1304-31 78 1304.34 61 1304.37 47 -1304.40 48 1304.43 SS 1304.4S 6S 1394.49 73 1394.52 67 1304.54 49 1344.57 37 1394.60 30 1304.63 25 1394.66 25 .1394.70 26 1394.74 2? 1364.77 28 1364." 29 1304.84 31 1394.87 39 1304.90 26 1304.93 23 .1304-96 23 1304.99 23 1395.03 22 130S.06 al 130S.09 21 130S.13 29 Suaps'Aded -Sediment Date -9/19/713 Track 2 Depth is So feet Tim -Sod-Conc Location (ft) Time. Sod.;C*nc Location (ft) EST "g/ I ri/S E/W EST mg/1 M/S E/U Time Sod-Conc Location (ft) EST mg/1 M/S E/U IS40.35 54 0 0 IS41.44 so IS49.39 S4 1542.41 69 1-541.47, 49 IS42.44 66 1540.43 54 1541.50 49 IS40.47, SS- IS41.0 49 -1542.46. 63 1S40.S1 SS 1541.SS 48 IS42.49 60 IS40.5S -54 IS41.-59 -49 IS4243 S7 IS48.58 54 IS42.SS S6 1541.62 48 IS49.62 54 1541.64 48 lS42.S8 56 MOAS 54 IS42.63 S6 IS41.69 48 1542.SS .54 IS40.69 57 1541.73 48 IS42.79 so IS40.73 ss 1541.7S 47 -1542.73 46 IS". 77 S9 1541 76 47 IS". as 61 IS41:79 63 IS42.78 1540.83 69 IS41.82 79 IS42.82 45- IS40.26 -78 1541.93 86 1542.84 4S IS40.29 99 IS41.84 86 1542.87 43 1540.92 ill IS41.8S 86 1542.89 42 15"43 114 1541.89 -99 1542.93 41 1540.95 lit IS41.99 It$ 1-542.9S 41 IS40.98 89 1S41.93 -110 1542.98 @40 1S41.01 79 1S41@96. jig 1S43. " 39 600 9 1S41.01 69 1543.04 39 IS41-64 es IS41.97 121 1543,07. -39- lS42." jig I'S41.07 104 1542.02 117 1543 11 41 IS41.09 JIS lS42.04 114 1543:14 41 1541.11 112 IS42.*S -113 IS43.17 39 1541.14 94 1542.09 lll@ 1-543.22 39 LS41-16 72 196 1543.28- 43 1541.19 62 1542.11 409 N' IS43.31 44 1541.2a IS42.14 112 - IS43.35 44 57 -206 ti 0 1S42.14 112 1543.3W 45 lS41.24 S2 IS42 17 In 11543.42 IS41.2S Sa IS42.*20 lot 44 IS41.27 S6 IS43.44 43- JS41.30 65 1542.24 9S 1S43-47 40 1S41.33 SO 1542.26, 88 IS43'.49 49 AS41.36 S3 IS42-29 7S@ IS43.SZ IS42.31 79 1541.38. So IS43.SS 38 -1542.34 69 .1541-41 so -1542.38 .71 1543.62 33 1543.64 37 Su*grnded Sediment Data 19/78 Track 2 (continued) -Depth is So feet -Time Sod.Colkc locat-lon (ft) Time Sod-Conc Location (it) EST ftg/ t @ . Time Sod-Conz Location (ft) H/s E/W EST mg/ I WS -E/U EST ng/t E/W 1543.69 38 IS44.96 .28 IS43.73 39 IS43.76 39 1545.01. a 999 A a. 1543.79 39 1S43.83 39 8" N 0 1S43.86 49 1S43.89 39 38 IS43.96 38 IS43.97 38 IS44.01 38 IS44.04 38 1644.09 38 IS44.12 38 IS44.IS 38 IS44.18 38 1S44.22 38 IS44.27 39 1544.32 42 IS44.35 42 1S44.38 42 1544.49 40 IS44.44 38, 1S44.47 35 IS44.S* 3s IS,44.S3 35 1544.58 33 Is".61 33 15,44.64 32 IS44.67 32 IS44..?* 30 IS44.72 39 1544.75 28 -1544.78 28 IS44.*82 28 IS44.84 28 1544.83 28 1644.92 27 Suamded Sediment Date 9 9/78 Track 3 Depth Is So feet Time Sed.Coac Location Ift) Time Sad.Conc Location (ft) T ime Sed-Conc Location (ft) EST mg/t H/S E/W EST mg/t H/S E/IJ EST Mg/-I NIS EoU ISS2.91 27 is" 0 1556.52 21 issa.89 1557.74 35 29 ISSS-56 21 1557.77 37 1553.37 31 1556.59 P-2 ISS3.79 33 a" 0 IS56.62 22 1557.80 43 ISSCIS 32 ISS6.65 28 IS57.83 49 1557.86 49 15S4.32 27 1556.69 29 ISS7.89 40 ISS4.44 30 1556.73 29 1557.92 34 ISS4.57 24 1556.76 as ISS7.94 30 IS554.66 28 1556.79 29 ISS7.97 28 1554.70 25 ISS6.8S 30 15S4.7? 31 ISS6.89 31 1S'S7.99 26 ISSBA2. 26 1554.82 31 6" N 0 1556.92 32 200 M 9 ISS844 26 ISS4.86 Z6 1556.95 36 ISS8:07 24 IS54.97 33 1556.98 38 1558.1-0 ISSS.*2 27 1557.01 33 24 isss.99 as -1557.04 28 IS58.14 24 ISS8.18 24 15S5.1s 22 IS57.07 26 IS58.22 24 15SS.29 23 IS57.10 25 1558.26 a4 tSS5.3S as IS57.13 26 -1558.30 24 155S.59 29 1557.16 27 1SS8.33 24 1555.67 3-1 1557.19 as ISSS.94 3e 1558.36 24 1557.22 27 ISS8.40 24 ISSS.90 as 1557.24 25 ISS8.44 24 ISM97 30 409 IS57.27 22 1558.48 27 1%6.02 31 ISS7.31 24 :1558.52 33 ISS6.09 21 1557.34 31 I-SS8.SS 36 1SS6.13 21 1557.37 32 1558.58 34 ISS6.16 26 1557.40 29 1558-69 32 ISS6.19 31 IS57.43 26 ISS8.63 32 ISS6.22 3S .1557.47 24 IS58.66 40- 1556.P.S 37 ISS?.Se 28 1558.69 64 1556.28 33 lSS7.-S4 33 isse.31 27 'ISS8.72 87 ISS7.57 35 ISS8.74 .16?. 19S6.34 * .22 ISS7.S9 34 ISS8.77 -tat ISS6.37 21 ISS7.62 33 ISS8.79 181@ ISS6.40 as 1557.64 !a ISS8.80 179 ASS6.43- 20 ASS7.67 32 ISS8.21 179 so H 0 lSS6.47 -a iSS7.71,, 34 ISS8.82 179. SU3 nded SedLwent Data ve ,9/78. Track 3 (c*ntinuod) Depth-13 50 feet Ti@ Sod-Conc Location Cft) Tine Sod-Coac- Location (ft) ime Sed.Conc, Location (ft) TST ag/l H/S E/U EST mg/l M/S -E/W EST mg/l H/S E/u ISS8.83 179 1%8.86 142 150.89 82 IM8.9e 45 1S58.94 36 1558.97 29 -ISSO.98 27 Isse.99 a6 ISS9.02 24 0 Suspended SedimeRt.DatwIl Track 4 Depth is So fact Time Sod-Conc Location (ft) Time Sod-Conc Location (ft) Time Sed.Cortc Location (ft) EST mg/l H/S E/U EST Mg/l N/S E/W EST Mg/l H/S E/U 1607.29 25 -200 S 0 .1608.14 as 1608.89 24 2" H 0 :Suaryided S*diment Date 9 9/78 Track S Depth is 50 feet Time Sed.Corc Location (ft) Time Sod-Conc Location Cttl Time Sed.Conc Location EST 00/1 M/S E/U EST mg/l H/S EST mg/ I M/s E/U 1609." 24 MKI 0 1611.34 21 1"9.63 22 1611.38 27 1609-66 22 1611.41 30 1609.67 22 1611.44 V 16".69 u 1611.47 26 1609.72 23 1611.SS V 1609.7s 22 1611.S3 .34 1609.78 22 1611.56 46 1609.83 22 1611.S9 S6 1609.97 22 1611.61 ss 1609.91 28 1611.6P S6 1609.94 31 1611.6s se 1609.98 34 1611@67 47 1610..62 37 1611.70 4S t619.95 37 1611.72 37 1610.69 42 1611.7S 30 1610.13 46 1611.78 26 1610.17 so 1611.81 23 1610.20 54 1611.84 22 1610-26 60 1611.88 22 1610-30 1611.91 22 1610.31 60 1611.9s 22 1610.33 S7 1612.00 24 1610.3S S4 1612.03 24 1610.37 sl 1612.9s 24 1610.38 sl 1612.08 24 L61S.41 se 1612-12 24 1619.4S 6s 1612.15- 24 1610.47 62 1612.18 24 MO.% so 1612.20 23 161O.S2 38 1612.24 23 1619.SS 30 1612.27 23 1619.57 2s. 1612.W 23 1610-S8 2S 1612-34 22 @200 S -0 1610-60 24. 1610.63 23 1610.6S U 1611.22 21 0 0 ad Sediment Datt: 6/78 Track I Depth is So feet* 'T ime Sod-Conc Location Uft) Time Sed.Con,c Locat:Lon (ft) T ime Sed.Conr- Location,M) EST mg/l N/S E/#J. EST mg/l H/S E/U EST mg/l N/S E/li 1042.01 2v logo m '0 1043.17 17 1044.44 IS 1"2.05 21 A943.20 lg@ 1044.47 13 W42.47 21 1043.23 17 1944-50 Is 1042.11 24 1043.26 16 16 1042.0 24 1043.29 .17 1944-56 is 1042.16 23 1043.32 A? 1044.S9 is 1942.19. 20 1043.36 16 1044.62 is 1042.22 16 1043.39 is 1044.65 16 1042.25 is 1943.42 16 1044.69 -16 -1042.28 Is 1043.4S is le44-72 46 L642.31 22 1043.49 is. 16 1042.33 .23 1043.S2 44 1044.78 14 1042.37 21 1043.55 13. 1044.80 -14 1042.40 23 1043.58 14 le44-85 14 1042,43 20 1043.62 14 1044.89 14 1042.48 21 1043-.6S it 1044-92@ 13 104241 21 1043.69 11 W44.96 13 1W.53 23 1043.72 12 104S.08 1-2 1842.56 21 1043.7S 12 1645.03 14 1842.59 21 10434?8 12 1-045.08 13 1"2.62 20 1043-.83 12 le45-11 13- 1042.66 22 1043.85 14 104S.16 12 1042.69 20 1043.89 13 104S.20 12 1042.?2 22 1043.91 is 1045.23 13 1$42.75 19 1043.94 is 1045-27 13 1042.79 18 1043.98 14 1945.39 13 1042.82 16 le44.92 13 1045.34 13 1942.8S IS 1044.05 12 1045.37 14 1942.88 24 1044.89 13 1045.40 1,4 1042.91 17 1044.12 t2 104SAS 14 1942.9S 14 1044.15 IS 1045.48 14 t842-97 is 1044.18 17 1045.70 14 1943.00 is 1044.21 14 800 N .0 104S.80 17 1843.03 16 1044.24 is 104S.97 14 1043.06 16 1044.27 15 104S.92. IS 1043.09 Is 1944.32 is 1045.97 13 1043.12 14 1044.35 13 1046.OS 13 1043.15 16 1944.39 @15 .1046.119 Is Suspended Sediment Data 9/26/78 Track I (continuied) Depth is So f salt Time Sed.Conc Location (ft) Ties Sed-Conc Location (ft) Time Sed.Conc Location (ft)- EST Mg/t M/S E/W EST 09/t N/S E /V EST mg/l N/S E/U 1*46.30 13 1048.03 is IOSI.39 9 1046.32 is 104B.05 12 1051.47 .9 1646.37 to 1048.06 21 ISS1.69 11 1W.40 12 600 N 0 1048.09 13 1051.65 12 10". 49 13. 1048.17 12 1051.79 is 1046.SS 13 1848.21 is 1051.89 It 1046.62 13 I848.a7 11 195I.S7 8 1046.70 13 1049.33 .12 1951.99 15 J946.76 16 1048.38 11 1051.95 to 1046.82 16 1048.42 9 IOS2.05 9 -200 S 1946.84 18 1048.46 is 1-946.84 al 1048.46 9 1046.98 is Ie4$.S6 9 1946.92 16 1048.S3 12 1046.96 16 1048.S? it 1946.97 18 1048.65 12 1947.00 Is 1048 71 13 1847.03 16 1048:?s -I@, 104?.09 14 1048.86 11 1047.13 16 1048.90, 12 1047AS 16 1048.95 Is 1947-29 13 1649.18 9 1947.25 12 1049.38 Is 1047.30 it t849.52 is 104?.34 -it 1949.68 Is 194?.37 Is 1049.78 12 104?.56 9 1049.87 it 1047.65 13 1950.02 11 1047.69 11 1050.17 11 290 N 0 104?.74 is 1059-35 to 1047.77 14 Is 1*47.80 11 1059.65 8 104?.83 12 lose.89 Is 1047.85 is 1959.93 is 0 1047.90, 12 400 N 9 1051.05 11 104?.95 is 1051.15 13 1047.95 12 losi.ae 9 1048.00 Suspended S'ediment. Oato 9/28/72 Track.l. Depth is 50 feet Timst Sed..Conc Location (ft) Timb Sed.Conc Locat-ion (ft) Time Sed.Conc Location (ft) EST mg/l H/S E/W EST mg/l N/S E/U EST -09/1 N/S E/V -JI44.60 st 8" N -0 114S.-IR 43 1145.81 4S 1144.63 39 114S.18 42 114S.83 44 U44.6S 37 1145.29 44 1145.83 43 1144.66 37 1145.21 45 1145.84 44 1144.69 37 1145-23 44 1145.86 43 1144.69 38 114S.24 43 114S.27 4? 11-44.72 36 114S.26 44 114S.88 44 1144.73 39 114S.28 43 1145.89 42 1144.74 38 114S.29 42 1-145.91 42 1144.74 40 114S.32 43 1145.91 42 11-44.76 39 il4S.35 42 114S.93 41 1144.76 41 1145.38 43 .1145.95 42 t144.77 40 1145.41 -42 1145.97 41 -1144.79 39 1145.41 44 1145.98 43 1144.79 41 1145.44 40 1-145.98 44 1144.83 38 1145.47. 43 1146.00 43 1144.94 114S.48 43 -1146.92 44 1144.86 37 .1145.50 -48 1146.03 45 1144.88 40 114S.52 38 t146.03 48 1144.91 41 1145.53 39 1146.04 4S 11,44.93 42 114S.SS 42 .1146.05 .47 1144.94 42 114S.56 41 @1146.05 49 1144.94 44 114S.S8 40 1146A9 44 1144.95 49 1145.59 49 1146.11 41 1144.98 46 1145.60 46 1146.13 43 1144.98 4S 46 1146.13 46 11,44.99 44 1145.62 46 44 .1145.01 47 1145.63 43 1146.16 45 114S.01 47 1145.64 44 1146.18 4S 114S.04 42 1145.65 43 1146.19 47 114SAS 41 114S.67 46 1146.21 48 .114S.06 43 114S.68 47 1146.23 48 1145.66 43 114S.70 44 1146.24 4S 1145.09 44 114S.73 40 1146.24 4S 114S.11. 44 1145.74 44 .1146.28 42 1145.14 42 1145.78 42 1146.30 43 114S I IS 43 1145.79 41 1146.33 46 114S.16 43 1145.89 44 1146.37 41 co Suspended Sediment Data 9/28/78 -Track I Cco'ntlnued) Depth is 50 feet Time Sed.Conz Location (ft) Time Sed.Conc, Location Uf L) Time Sed.Conc Location (ft) EST mg/l -N/S E/W EST moll t4ls E/U EST mg/l H/S E/Ul -1146438 -41 114G.". 40 1147.75 37 1146.39 42 1146.99 36 1147.78 35 1146.39 43 1146.99 37 1147.80 42 U46.43 41 1146.99 41 1147.81 40 11-46. 46 41 1147.92 38 11-47.83 36 1146.48 40 1147.95 38 .1147.84 36 1146.49 42 1147.08 36 11-47.86 -36 1146.49 42 1147.10 36 1147.88 35 1146.53 39 1147.11 36 1147.88 38 38 1147.14 36 1147.89 37 1146.SS 39 1147.17 37 1447.91 34. 1146.-58 40 1147.19 37 1147.92 36 1146.60 40 1147.23 37 1147.93 :37 It46.61 40 1147.26 37 1147.94 37 U446.62 AS 1147.26 37 1147.96 36 @1146-63 44 1147.29 37 1147.98 .36 1146.65 44 1147.31 37 -1148.09 38 1146-66 4e 1147.3S 38 1148.00 39 1146.67 41 1147.38 3S 1148.03 377 1146.69 4e 1147.41 36 1148.04 37 1146.71 39 1147.42 40 1148.08 37 1146.72 40 1147.44 37 1148.10 37 1146.74 Q 1147.44 42 1148.13 38 1146.75 40 1147.46 39 1149.15 39 1146.78 37 1147.48 36 1148.15 40 1146.78 39 1147.48 40 1148.18 36 1146.79 49 1147.49 40 1148.18 38 U46.80 39 1147.53 37 1148.18 39 1146.81 40 1147.56 36 1148.21 37 600 K 0 1146.83 41 1147.56 37 1149.24 37 1146 84 39 1147.59 -37 1148.28 36 1146:8S 38 1147.62 36 .1148.30 39 1146.8S SO 1147.65 35 1148.33 440 IL46.87 44 1147.68 36 1148.3S 41 t146.99 39 1147.68 37 1148.39 '49 U46.99 37 1147.70 3S 1148.41 -40 1146 93 38 1147.71 36 1148.43 .42 -1146: SOS 40 1147.72 37 1148.46 42 110 Suspended Sediment Data 9/28/79 Track I (continued) Depth is so feet Timis Sod--Conc Location (ft) Time Sed.Conc Location (ft) T-ime Sed.Conc Location (ft) EST mg/l N/S E/U EST mg/l H/S E/U EST mg/t, H/S E/W 1148.48 41- 1149.16 44 37 1148.49 -41 1149.16 44 11SO.03 36 1148.53 41 1149.19 42 1150.06 36 1-148.S6 41 1149.21 44 1150.09 40 1148 S8 41 1149.24 45 1150.10 37 1148:59 41 1149.27 44 1150.11 40 1148.-59 47 1149.29 44 IISO.12 410 1148.61 44 1149.33 44 1148.64 41 1149.3S 44 1150.15 37 1148.66 41 1149.39 44 1150.19 34 -1148.66 43 1149.43 43 .11se.23 34 1148.69 -40 IISO.25 34 1149.44 43 IISO.27 3S 1148.70 41 '1149.46 45 1148.73 41 IISO.28 .38 1149.47 46 1150.29 41 1149.74 41 1149.49@ 4S 1150.31 36 1148.75 41 1149.Sl 46 1150.34, 32 1148.76 45 1149.54 43 IISO.35 32 1148.78 44 1149.5.4 44 1150.38 32 1148.79 42 1149.S7 46 IISO.39 31 1148.81 AL 1149.S8 44 1160.40 33 1148.84 41 .1149.60 43 1150.43 34 1148.87 44 1149.64 42 36 1148.99 44 1149.6? 41 1148.90 41 1149.68 41 1150AS 38 IL48.91 40 1149.69 42 -1150.48 38 1148.93 41 1149.70 44 11SO.50 40 1148-95 49 1150 S3 39 1148.95 41 1149.72 43 1150:56 41' 1148.96 44 1149.74 41 1150.69 40 1148.98 43 1149.74 43 IIS9.63 41 1149.00 44 t149.74 43 1159.65 Q 1149.03 44 1149.78 38 1159.68 43 1149.-94 44 4149.83 37 1159.71 39 1149.06 1149.83 43 1150.74 42 S4 1149.86 37 1150.78 41 ii4g.96 ss 1149.87 37 1150.79 40 1149.99 46 1149.90 37 1150.81 37 1149.12 44 1149.93 38 IISO.84 35 -A149.13 43 1149.96 37@ Ilse.88 3S Go C) Suspended Sediment Data 9. 8/78 Track I (continued) Depth is SO lost Use Sed.Conc Location (ft)- Time Sed.Coftc. Location -1 f t) Time So' d. Cowc Location (ft) EST mg/l N/S E/U EST g/.t N/S E/W -EST "g/l N/S E/W 1150.90 34 IISI.77 37 IIS2. .73 44 ILSO.91 34 IISI.79 39 VIIS2.75 38 11SO.93 36 IISI.83 37 1152-79 31 IISO.97 38 IISI-86 36 IISI.00 43 115.1.82 38 IIS2.81 32 1451.03 43 AISI.91 41 1152.83 34 IIS2.87 31 IIS1.05 44 IIS1.94 39 1152.88 31 44 IISI.97 40 IIS2.96' 31 fist-.19 45 1152.00 39 1152-93 33 Itst.12 46 JIS243 -39 IIS2.96. 31 1151,13 43 1152.07 37 1152-98 39 IlSt.16 43 IIS2.10, 36 -400 4 9 1-151.02 33. 1IS1.17 47 IIS2.13 37 IIS3-e3- 37 t151.18 46 -IIS2.15 .38 I-IS3.05 3a fisi. 1-9 44 1152.18 37 1153.08 32 Ils"21 43 IIS2.18 34 1153-11 36 IIS1.24 42 1152-19 34 1153-1.1 37. 11-S1.28 41 ILSE-20 37 1153.14 33 IISI.31 41 1152.21 35 1153.14 37 11SI.34 41 iIS2.24 34 AIS3.17 @33 11SI.37 40 - 1152.2S 35 1153.20 -31 11S1.39 39 IIS2.28 34 1151.43 49 IIS2.31 34 IIS3.22 11S3.25 31 HS1.43 42 IIS2.33 36, IIS3.28 33 11SI.46 42 1152.34 35 1153.31 34- IISI.48 38 IIS2.37 31 1153.32 36 11S-1.49 49 iIS2.40 33 IIS3.32 36 IlSl.52 40 U52.42 32 1153.3S 3S .11SI.S6 40 IIS2.43 34 1153.38 34 IIS1.59 37 IIS2.4S 36 1153.41 -34 1IS1.59 35 1152.49 33 IIS3.44. 34 11SI-61 37 1152-53 34 1153.47 33 1151.41 38 IIS2.55 34 1153.50 32 11S1.64 36 IIS2.58 3S IIS3.54 31 IISI-68 3S 1152.69 3S 1153.S? 31 IISI.70 35 1152.63 3S 11S3.68 31 11SI.73 35 1152.68 33 IlS3.63 31 36 IlS2.72 31 -1153-66 31 ILO Susrnded Sediment Data 9 8/78 Track 1 (continued) Depth i3 SO feet Tim@ Sod-Conc Location (ft) Time Sed-Conc Location (ft) Time Sed-Conc Location (ft) EST 09/1 M/S E/U. EST mg/t H/S E/U EST ag/l M/S E/W IIS3.69 30 1154.57 30 1156.89 29 1153.72 29 1154.58 31 1156.94 29 1153.?4 39 1154.59 38 IIS6.97 28 1IS3.78 31 1154.69 36 1156.98 34 IlS3.99 39 1154.63 31 1157.03 29 1153.81 30 IIS4.64 31 1157.05 31 IIS3.83 33 1154.68 31 IIS7-13 29 IlS3.84 31 U54.70 31 1157.16 29 1IS3.88 39 1154.73 32 1157.19 27 1153.89 39 1154.77 32 1157.21 31 1153.92 34 IIS4.80 30 1157.24 28 IIS3.94 36 1155.07 28 IIS7.28 39 1153.96 31 1155.25 29 Zee N 0 IlS7.29 29 1153.98 31 IISS.25 31 1157.30 31 IIS3.99 -31 115S.40 30 1157.31 29 1154.02 33 1155.56 28 1157.34 28 1IS4.04 33 1155.60 30 1157.36 31 1154.08 30 1155.68 29 1157.40 29 1154.1a 31 1155.84 30 1157.42 30 1154.15 30 1155-94 as 1157.46 28 1154.17 30 1155.99 31 1157.49 29 1154.29 3e IISS-03 29 1157.52 39 IlS4.22 30 1156.09 30 1157.S4 28 1154.24 3e 1156.17 29 1157.SS 28 US4.25 33 1156.24 28 1157.SS 29 IIS4.26 35 1156.32 30 AIS7.61 29 IlS4.28 30 1156.33 28 1157-63 31 IlS4.28 39 IIS6.38 31 1IS7.65 33 1154.31 39 1156.43 29 1157.66 33 11S4.34 30 1156.44 31 1157.68 33 1154.38 29 1156.47 29 1157.70 33 1IS4.41 31 1156.49 31 1157.74 39 US4.44 30 1156.50 29 1IS7.74 40 1154.46 38 11S6.65 29 1IS4.46' 32 1157.76 39 IIS4.47 37 IISG.74 29 1157.79 36 1156.80 29 1157.83 31 1154.50 31 1156.81 31 1157.8S 34 1154.SS 29 1156-83 39 1157.88 36 00 Sus ded Sediment Data 8/78 -Track I ftontinvmd@ Depth is 50-feet Tknin Sed.Conc Location (ft) Time Sed-Coac Location (ft) Time Sed.Conc- Location -@ft) EST 09/1 -H/S E/u EST mg/A N/S EAJ EST mg/j. f4/S E/U 34 IISS-83 29 11159.S2 3a IIS7.91 36 11.58.84 33 IIS9.54 .30 IIS7.93 42 1158.84 -37 IIS9.S7 29 IIS7.94 40 liss.88 34 -IIS9.59 29-- IIS7.98 37 1158-93 31 1159.61 as 1IS&M .35 0 0 IISS.95 29 1159.62 30 1158,44 33 IISS-96 -30 IIS9.63 30 1158 95 32 -IISS.97 31 HS9.64 29 .1168:09 33 1159.90 31 11S9.67 30 -IIS8.11 33 IIS9.02 29 IIS9.68 31 IlS8.14 32 1159 43 32 110-18 '3S IIS8.17 31 11S9.94 37 11S9.70 39 Ilse.-Is 31 1159.96 28 1159.72 39 liss.21 31 11S9.99 as 11S9.74 31 IlS8.P-3 32 11S9.16 27 1159.74 31 it-Sa.27 3S 11S9.1a 39 1159.76 30 1-iss.28 36 11S9.13 31 -11S9.78 30 36 IIS9.1s 30 11S9.81 28 IIS8.3S 3S 11S9.16 39 IIS9.84-, 29 IIS8.38 34 11S9.18 26 IISS-38 33 IIS9.21 27 11S9.86 29 IISR.43 33 IIS9.24 27 11S9.87 30 IISBAS 34 1159.89 as @1159.27 29 -1159.91 28 USBAS 34 IIS9.19 -29 @1159.93 30 lIS8.S2 3S 1159.33 29 1159.93 29 IlS8.S5 36 IIS9.34 32 11-S9.96 28 IIS8.S8 34 IIS9.36 31' 11S9.98 29 1158.61 32 1159.36 29 1290." 28 1158.64 35 1159.38 3S 1200.03 -28 IIS8.66 3? 1159-381 33 1200.14 27 -11SB.67 11M41 29 1200.17 27 llS8-68 38 1159.42 28 1290.19 28 IIS8.71 34- 1IS9.4S 28 1200.22 as IlS3.73 33 11S9.48 29 1200.24 28 1ISS.74 32 1159.49 30 iaee-v@ 29 1158.75 31 1159.So 30 1209.31* -30 1158.78 33 1159.Sl 30 IISS.81 3V 1159.52 29 1290.34 27 1200-37 28 Su3p*nded-Sediment Data 9/ps.,78 -Track I (continuedl Depth i3 S49 f set Ulm Sed-Conc Location (ft) T-Loo Sed.Conc -location -tft) 71me Sod. Covkc'- Location (ft) EST mg/t M/5 E/W EST mg/t N/S E/U -EST mg/t "/S E/U 12".29 29, 1291.85 27 1202.93 27 12". 42 29 1201.86 29 1202.96 -27 12". 4S 27 1291.92 27 1203.04- _27 1290.48 28 1201.96 28 1293.06 .29 12".52 27 1291.97 27 1203.07 27 IM.54 30 1292.91 30 1203.09 29 12".S7 38 1292.04 28 1203-14 27 12". " 29 1208.06 28 12,03.19 27 12".64 @ES -1202.97 33 -1203.22 27 12".67 29 1202.10 31 1203.23 30 12".69 29 1202.13 31 IM-28 28 1209.72 29 12ee-16 30 1203.33 28 1290.75 27 1202-19 29 1203.39 V 1209.77 29 1202-23 28 1299.79 31 1292.28 28 1203.41, 27 12e3.43 39. 1290.81 39 -2" S 0 1202.31 28 1203.47 29 1289.82 28 1292.36 28 1203.S2 27 -480 S 0 1290.84 29 1292-39 29 1290.87 29 1202.41 34 I-a". 89 29 1202.42- 33 1290.95 29 1202.44 31 12" - 99 28 1292.46 -29 1291.02 29 1202.49 29 1291.98 28 1202.51 30 12*1.12 as 1202.S4 28 1291.21 28 1292.SS 30 1201.28 27 1292.60 29 1291.35 29 1202.64 as 1201.38 28 1202-66 28 .1201.41 29 1292.66, 3a M.42 27 1202.69 29 Ic 1291.44 32 1202-69 39 1291.49 28 1202.7-6 29 120I.S9 27- 12e2.89 29 1291 .67 27 1202-83 28 1201.7S 27 1202.84 31 1201.79 26 1202.8? -39 1201.81 as -1202.99 28 00 Suspended Sediment Data 9/26/79 Track 2 Depth LS SO feet Ties: Sed.Conc Location (.it) Time Sed.Coar, Location Jlt) Time. Sed,Conc, Location (it) EST mg/l M/S E/w EST' mg/l H/S --E/U EST mgll,. NIS E/U 1104.02 8 a 0 IleS.28 24 1106.54 14 1104.05 9 IIOS.31 23 1106.S7 is 1194.08 9. 1105-34 22 1106.6e is 1184.11 9 IleS.37 20 11" .63 19 1104.13 9 IIOSAG 19 1186.67 is 1104.16 9 IISS.44: IS 1106-71 17 -1194.19 a IIOS.47 14 1-106.74 17 4104.22 9 _119S.51 12 1106.79 .17 1104.24 9 USS-.54 12 1106.82 17 .400 N e 1104.28 9 118S.99- 14 1196.86 1-6 1104-31 9 Iles.,62 is 1196.89 is 1194.34 9 lies-66 12 _1 1,96. 92 12 1104.39 9 1195.69 11 1106.96 :11 LISC42 10 1105.74 11 1106.'99 le Ile4.47 is 1105.77 1-0 1107.03 9 -SO 9 119S.80 to 1197.'06 to AIM 1IMS3 to 1105.82 11 1107.09 13 110CS7 10 1105-86 9 1197.11 16 1104.61 to 1195.19 9- 1107.43 Is li94.65 -10 1185.92 12 1107.16 2e 1104.69 W lies.96 12 1197.21 21 1104.72 to 2" h 4 1195.99 to 1197.26 22 1104.75 10 .1106.02 11 1197.29 @2e 4104.77 19 1106.07 1@ 1107.31 21 1104.81 12 1106.11 12 1107.3S 21 U94.83 17 1196.14 11 1107.38 20 1404.86 20 Ile6.17 11 1107.42 19 28 1106.22 12 lle7.46 18 IL04.91 37. 1106-.24 13 1107.Si 15 1194.94 40 -1106.27 17 1107.S4. -IS 1184.99 38 11-06.29 19 1107.58 is 110S.03 36 1106.32 21 1 Ie7 -61 16 IIOS.06 34-- 1106.3S 22 1107:6S 19 1195.09 32 1106 38 22 11-97.-68 is 1185-13. 30 1106:41 20 1107.71 IS 1105.16 29 1106.44, 17 1197.73- 17 119S.19 28 1106. 47 is 1107.76 19 1105.23 29 1106.S2 13 1107.79 is 00 -Suspended Sediment Date 9/26/78 Track 2 (continued) Depth is 59 feet Tim Sed.'Conc- Location-(ft) Time Sed.Conc Locati-on C-ft) Time Sed.;C"z Location (ft) IST mg/l N/S E/W EST &9/t N/S E/u .-EST ug/t -N/S E/IJ 1107.84 17 1109.e7 21 1110.3@ 26 1187.87 Is 1199.11 19 1110.40 22 1197.91 19 1189.1s is .1119.44 Is 110?.93 22 .1109.18@ is, 1110.48 16 1107.96 26 1109.23 17 1110-53 13 1107.98 29 1199-26 is 1198.01 31 600 M 0 1109-29 17 1118.61 12 1-108.94 28 1109.32 17 1110.64 12 ties-es 28 1109.36 14 1110.68 12 1108.12 28 1109-39 14 1110.72- 11 1108.14 29 1109.43 14 1119.76 to I Los. 147 32 1109.46 13 iiie.,79 -is 1108.2e 29 Is 111,0.82 Is 1108.-23 29 1109.56 15 1119.86 -1@ A 198. a 23. Ileg.60 15 see N a 1119.88 to 1108,31 27 Ileg.63 is 1110-91 1-2 1108.34 27 1109.66 Is 1119.93 12 -1108'.39 29 1109.71 16 1110.97 to 1108.42 32 1109.74 14 1119.99 to 1198.44 32 -1109.77 13 111-1.03 19 1108.47 33 Ileg-79 13 .1111.06 -10 lies-st 32 1189.82 is 1111-08 to 1198-53 33 1109-86 13 .1111.11 to 1198.57 30 1109.Bs 13 1111.14 to 1198.60 26 1199.92 17 1111.18 to 1198-63 27 1109 95 23 111t.24 to 1040 N :0 1108.66 31 1189:98 28 ttes.69 38 1119.01 30 1198..72 37 1110.03 30 1198.76 37 1110.07 31 1198.79 34 ills.-09 31 1108.83 -28 1119.14 30 11,08.86 24 1119,17. 29 1198.88 27 1119.19. 30 1198-92* 26 1110-22 32 1198.98 as Ill-9-25 27 1189.01 25 1110.30 26 1199.04 23 1110.33 29 00 Suspended Sediment Data 9/26/78 Track 3 Depth is 50 feet Time Sed.Conc Location (ft) Tifee Sed.Conc Location (ft) Time Sed.Conc. Location (ft) EST 09/1 N/S E/W EST mg/l H/S E/U EST Mg/l M/S -E/U 1749.11 7 ION N 0 1750.28 S 17Sl.S9 to 1749.14 4 17SO.30 16 see N 0 17SI.61 is 174g.t7 8 1750.34 9 1751.65 7 1749.19 14 1750.37 7 1751.68 7 1749.23 5 1750.39 10 17SI.72 8 1749.26 to 1750.43 8 17SI.7S 16 1749.29 8 17SO.45 11 17`51.78 is 1749.32 12 17SO.49 to 1751.82 7 600 H 0 1749.35 11 1750.52 9 1751.84 9 1749.38 7 [email protected] 6 17SI.88 a 1749.41 12 1750.60 6 17SI.90 11 1749.44 8 1750.64 12 17S1.94 11 1749.47 13 1750.68 a PS1.97 10 1749.50 13 1750.71 6 1752.01 8 1749.53 16 1750.74 S 17S2.04 10 1749.57 13 1750.79 6 1752.08 4 1749.60 14 1750.83 4 1752.11 3 1749'.63 1-750.86 2 1752.14 7 1749.65 9 1750.88 S 17S2.19 le 1749.68 to 1750.91 11 1762.23 5 1749.71 5 1750.93 17 1752.25 5 1749.74 S 1750.97 10 17S2.28 7 1749.78 5 1751.00 to 17S2.31 11 1749;80 8 1751.04 7 17S2.34 7 1749.83 it 17SI.08 10 17S2.37 13 1749.86 to 1751.13 14 17S2.40 S 1749.89 S 1751.16 12 1752.44 5 1749.93 21 17Sl.*lg 9 1752.49 16 1749.96 9 1751.22 9 1752.52 7 1749.98 11 17SI.,25 9 -1752.54 to 1750.01 12 17SI,29 6 17S2.58 7 1750.OS is 1751.34 is 17S2.60 a 17SO.08 9 17SI.39 7 17S2.63 11 1750.10 13 @1751.43 6 1752.66 8 17SO.13. 11 I?SI.46 19 1752.70 5 1758.18 6 1751.49 11 1752.73 .7 1750.21 -6 1751.52 19 1752.76 6 1750.24 7 175I.SS .6 17S2.78 9 00 Suspended Sediment Data 9/26/78 Track 3 (continued) Depth-i3 50 feet Time $ad.-Conc L*cati on Xft) Time Sed.Conc Location (ft) Time Sed.Conc -Location (ft) EST mg/t N/S E/U EST Mg/l N/S EAJ -EST mg/l N/S E/U 1752.83 5 17S4 AA 9 1755.22 it 6 1754.08 Is V?ss. 26 12 17SE.89 13 1754.1e to 1755.29 11 17S2.92 9 1754.13 to 17SS.32 6 1752.95 20 1754.16 8 17SS.3S 5 to 47S4.20 a 175S.38, -6 1753.03 -6 1754.23 12 17SS.42 7 1753.OS -8 1754.28 to 1-7SS.44, a 1753.08 14 17S4.33 8 1755.47 to VS3.11 7 4eO N 9 1754.36 1-6 IM.50 9 17S3.13 17 PS4.40 7 17SS.53 23 1753.18 a 1754 43 8 .1755.56r: 12 17S3.20 le 17S4:46 9 17SS.59 8 t7S3.23 9 17S4.49 S 17SS.61 9 -17S3.27 7 1754.52 13 17SS.64 9 1753.29 9 17S4.55 it 1755.67 1753.33 It 1754.Sg it 17SS.7-0 to 17-53-35 27 1754.61 9 1755.73 19 1753.33 6 17S4-65 3 17S5.76 8. 17,53.41 it 17SC-68 6 17SS. 78- -8 1753.47 9 1754.70 6 1755.81 - .9- 1753.50 -7 17SC73 .8 175S.94 7 1753.53 6 17S4.76 7 17.55.87, 12 1753.56 7 1754.79 9 17S5.91 7 1753.Sg a 1754.81 15 1_755@ 93 11 1753.62 9 1754.84 9- 1755.97 9 17S3.64 to 1754.85 26 1755.99 11 17S3.69 It 17S4,88 19 1756.03 9: 1753.71 1754.89 16 17S6.06 9 1753.75 9 1754.91@ 13 17S6.19- 14 1753.79 4 17S4.94 11 17S6.13 S IM-81 a 1754.97 7 17516 - -17 G 1?53.84 4 1754-99 to 17S6.19 11 1?53.88 4 1755:83 8 17S6.23 1753491- 4 1755.06 5 1756-26 9 1753.94 7 17SS.99 a 1756.30 10 17S3.98 .6 17SS413 to 29e M 9 1756.3S 11 1754.02 6 1755.19 9 .1756.38 ..-12, CO 00 Susrnded Sediment Date 2G/78 Track 3 (continued) Depth is 50 feet Time Sed.Conc Location Ut) Time Sed.Conc Locationl(ft) Time Sed.Conc Location (ft) EST wg/l M/S E/U EST mg/t @H/S E/U EST mg/l NIS E/U 17S6.40 28 0 0 1767.49 49 A758.75 6 1756.44 is 1757.53 32 .1758.78 6 1756.48 7 1757.57 is 1758.ae a 1757.59 7 17S8.84 l?S6.S3 1@ 1757.69 11 1758.88 le 175&55 Is 1757.63 Is -1758.90 14 -499 S 0 17S6.59 12 1757.66 13 17S8.94 7 17S6.62 8 1757-69 10 17se.99 6 17S6.65 14 17S7.73 10 1759.01- is 1756-68 9 1757.75 13 1759.05 9 17S6.72 5 1757.80 17 -209 S a 1759.09 is 17S6.75 6 1757@84 17S9.13 12 1756.78 7 1757.88 R 17S9.16 it 1756-80 1757.90 10 1759;19 9 1756.83 15 8 1759.23 a 1756.85 22 1767.98 14 1759.26 8 1756.89 1 1758.03 8 17S9.30 to 17S6.91 10 1758.05 to 1759.32 12 -1756.94 13 1758.08 it 1769.3S 1-4 1756.98 9 1758.10 11 1759.38 9 1757.00 26 17M 13 12 1759.42 9 17S?.93 it 1758.16 8 1759.46 9 1757.96 13 1758.19 18 1759.49 10 1757.99 9 1758.22 13 1759 , 51 12 -l7S?il3 8 1758.25 to 1759.54 7 1757.17 a 17S8.28 to 17S9.57 10: 1757@20 9 1758-33 a 1759.60 7 1757.23 13 1758.37 7 1759.63 9 1757-26 14 1758.39 8 1759.65 to 1757-@30 14 1759-43 11 1759.71 5, 1757s33 -8 1758.4S 13 1759.73 17 1757.37 9 1758-48 13 1759.74 11 1757.40 14 17M51 11 1759.78 7 1757A2 is 1758,SS 14 1759.78 17 1757.44 72 1758.59 .9 1759.20 to 17S7.47 36 17S8.63 4 1759.83 5 17S7.48 30 1758.67 6 1759.88 S 17S7.49 67 1758.72 4 1759.90 7 Suspended Sediment Data 9/26/78 Track 3 (continued) Depth is Se feet Timat Sed.Conc Location (ft) Time Sed.Conc Location (ft) Time, Sed.Conc Location (ft) EST mg/l WS E/U EST mg/l N/S EN EST mg/t WS E/U 1759.93 S 1801.03 9 17SS.94 S 1891.86 13 1759.95 22 1801.08 21 1759.97 9 1891.10 Is 1,759.98 9 1891.11 13 18".99 12 -600 S 0 1801.11 21 1800.03 9 1801.13 17 1890.06 6 1891.16 14 18".08 S 1801.19 14 to". is -7 1801.22 16 I SM. 12 16 1891.25 Is 1380. 13 18 1801.29 14 18".16 to 1801.31 17 1800.20 9 Igel.35 18 1800.23 It Igel.38 20 18". 25 12 1801.41 14 12". 39 7 1801.4S 17 IS". 33 is 1801.48 22 1800. 37 14) Igel.53 1-9 18".40 8 18el.56 8 1900.43 4 1801.59 4 18". 46 4 1891.63 9 -a" S e 1809.48 It 1899.52 12 1809.57 S 1899.60 Is 1890.66 4 1800.68 to 1800.73 5 1890.75 S 1809.80 6 1899.83 a 1809.85 a 1899.88 9 1809.92 12 1899.99 7 1891.99 a - 1891-93 7 Suspended Sediment Data 9/28/78 Track 2 Depth is 25 feet Time Sed.Conc Location (ft) Time Sed.Conc Location (ft) Time Sad.Conc Location (ft) EST Mg/l N/S E/W EST mg/l H/S E/W EST mg/l M/S E/u 1210.80 22 -400 S e 1216-80 at 1210.91 21 1216.87 21 1211.03 22 1216.94 22 1211.94 22 1217.05 23 400 N a 1211.14 21 1217.29 22 1211.32 21 12-17.52 23 1211.S4 20 1217.66 22 121l.77 20 1217.89 21 1212.94 2e 1218.04 22 1212.29 20 -200 S 0 1218.17 23 1212.42 21 1218.30 22 1212.S4 21 1218.48 23 1212.76 20 1218.69 24 600 N a 1212.87 20 1218.86 as 1213.00 21 1218.94 24 1213.17 21 1219.10 23 1213-34 21 1219.33 24 1213.51 21 1219.49 24 1213-67 21 1219.61 -24 1213-86 21 a 0 1219.76 24 1214.09 21 1219.97 24 Soo N 0 1214-33 21 1214.56 20 1214.85 2e 121S.15 21 121S.42 21 1215.68 21 200 H 1215.91 at 1216.14 21 1216-23 20 1216.29 22 1216.34 22 1216.40 21 1216.50 21 1216.S$ 21 1216.64 20 1216.68 21 1216.?S 23 SU.3pended Sediment Data 9/28/78 Track 3 Depth 13 50 feet Tim Sed.CoAc Location (ft) Time -Sed.Conc Location (-f t) Time Sed.Conc Location (F-t) EST@ mg/l H/S E/U EST mg/l N/S E/W EST Mg/l A/S E/u 1226.60 24 8" A -209 U 1226.70 23 1226.95 at 1227.93 21 122?.14 ig 1227.35 19 1227.60 Is 1227.87 Is 1228.03 17 1228.26 17 1228.S7 16 1228.79 16 1229.01 16 8" N 299 E Suspended Sediment Data 9/28/78 Track 4 Depth is 50 feet Time Sed.Conc Location (ft) Time Sed.Conc Location (ft.) Time Sed-Conc Location (ft) EST mg/l M/S E/U EST M/S E/U EST mg/l N/S E/U 1231.13 is 690 H 200 E 1231.47 18 1231.76 17 1231.98 17 1232.19 19 lZ32.49 19 1232.62 19 1232.81 19 1233.9S Is 1233.28 is L233.52 19 1233.96 19 1234.10 19 1234.38 19 1234.58 18 1234.80 2e 1234.97 20 1235.17 20 1235.50 19 1235.79 19 1236.10 19 1236.48 20 1236.56 22 1236.70 23 1236.87 23 1236.96 23 1237.9S 23 1237.15 23 1237.29 21 1237.25 is 1237-36 18 1237.42 19 1237.57 Is 1237.75. 19 1237.9S 19 1238.14 19 1238.31 19 600 h -200 u qp Suspended Sediment Data 9/28/78 Track 5 Depth- is 50 feet Time Sed.Conc Location (ft) Time Sed.Conc Location (ft) Ti.me Sed.Conc Location (ft) EST mg/l N/S E/U EST mg/l N/S E/W EST mg/l N/S E/U 1393.10 32 400 M -200 U 1304.50 28 t363.13 30 1304.55 27 1383.17 31 1394.61 27 1383.20 29 1304.65 28 1303-24 31 1304.69 27 1303.39 31 1304.80 27 1303.33 32 1304.86 27 1303.36 31 1304.92 26 1303.38 29 1304.9S 25 1393.43 30 1304.96 28 1383.46 32 1305-00 27 1303.50 32 1305.e6 26 1303.SS 32 130S.08 27 1303.60 29 130S.13 25 400 M 200 E 1303.61 32 1303.64 29 1303.66 30 1303.71 29 1303.75 31 1393.80 29 1303.8S 29 1303.90 26 1303.93 27 1303.98 29 1304.01 V 1304.03 26 1304.08 26 1304.11 26 1384.11 28 1304.16 26 1304.23 26 1304.26 29 1304.29 29 1304.30 27 1304.35' 28 1394.39 29 1304.43 27 1304.4S 28 Su3rnded Sediment Data 9 28/78 Track 6 Depth i3 SO feet Time Sed.Conc. Location (ft) Time Sed.Conc Location (ft) Time Sed,Conc Location (ft) EST mg/l m/S E/U EST wg/t N/S E/u EST Mg/ L. N/S E/W 1306.66 28 2W M 300 E 1308.68 29 1310.08. 30 1306.68 a? 1309.68 30 me.es 28 1306.71 28 1309.71 27 131-0.14 29 1306.81 27 1308.79 29 1310.17 29 1306.88 28 1308.86 28 1310.19 29 1306.92 29 1308.93 29 1310 .'23 29 1386.93 28 1308-95 30 1310.2s 29 1396.93 30 1308-96 28 1310-29 29 1306.,96 28 1309-01 28 1310.33 29 1397.02 29 1399.08 28 1310.37 3e 1307.03 28 1309-13 28 1310.41 33 097.07 as 1309.19 29 1310.43 3S 1307.11 28 1309.2s 28 .1310.48 39 1307.16 27 1309.31 28 1310.50 42 1307.19 30 1309.36 29 .1310.51 42 1307.28 29 1309.37 32 1310.54 45 1307.39 28 1399.41 28 131O.S7 46 13e7.48 28 1309.47 28 1310.60 46 13e7.55 29 1309.49 30 1310.62 46 1307.69 28 1309.49 31 131e.63 4S 1307.7S 27 1309.53 29 1310.64 44 1367.83 27 1309.58 28 1310.66 44 1307.84 28 1309.62 28 1310.67 43 1307.88 27 1309.G4 29 131e.69 41 .1308.04 28 1309.68 29 Me.71 36 1308.17 27 1309.69 28 1310.71 34 1308.27 29 1309.72 as 1310-73 31 1308.29 27 1309.74 29 1310.74 31 098.34 27 1309.77 27 1310.77 29 1398-36 30 1309.78 31 1310.77 29 1398.36 28 1309.82 27 1319.80 39 1308.39 30 1309.84 29 1310.81 42 1308.42 27 1309.86 27 1310-83 47 1308.48 28 1309.93 29 1310-84 51 1398.53 29 1399.93 28, 1310.87 55 1398.S8 28 1309.98 29 1310-88 58 1308.64 28 1399.99 28 1310-99 57 1308.6s 30 1310.00 29 1310.92 56 Ln Su;pended Sediment Data /28/78 Track 6 (continued) Depth i3 50 feet Time Sed-Conc Location (ft) Tise Sed.Conc Location (ft) Time Sed-Conc Location (ft) EST Mg/t NIS E/W EST wg/l NIS E/W EST Og/t NIS E/W 1310.94 S6 1311.79 32 1312.69 44 1310.95 55 1311.80 31 1312.72 43 1319.97 54 1311.84 30 1312.73 44 1310.98 53 1311.86 30 1312.79 44 1310.99 55 1311.87 31 1312.83 42 1311.9e 56 1311.89 30 1312.84 41 1311.04 52 1311.96 39 1312.87 41 1311.05 S2 1311.93 39 1312.89 42 1311.08 57 1311.95 30 1312.90 .42 1311.11 so 1311.98 31 1312,92 39 1311.14 62 1312M 31 1312.97 41 13U.17 64 1312.91 31 1312.99 37 1311.19 69 1312.04 30 1313.92 36 1311.22 69 1312.07 32 1313.04 34 1311.24 62 1312.09 35 1313.07 34 1311.24 59 1312.11 36 1313.09 33 1311.27 51 1312.14 39 1313.12 32 1311.3e 46 1312.17 46 1313.1S 31 1311.32 44 1312-22 43 1313A8 32 1311.33 44 1312-22 41 1313.21 31 1311.34 45 1312.24 38 1313.25 32 1311.37 AS 1312.25 35 1313.28 32 1311.41 42 1312.28 33 1313.31 31 1311.43 39 1312.30 29 1313.33 32 1311.46 36 1312.33 28 1313.35 32 1311.46 3S 1312.35 28 1313.39 33 1311.49 31 1312.39 28 1313.42 33 1311.50 30 1312.43 28 1313.43 33 1311-53 n 1312.46 30 1313.45 34 1311.55 29 1312.49 31 1313.49 35 1311.58 29 1312.59 31 1313.53 36 1311.59 39 1312.53 32 1313-56 37 1311.63 30 1312.55 34 1313.59 36 1311.65 29 1312.56 38 1313.62 35 1311.69- 29 1312.59 41 1313.65 37 1311.72 30 1312.60 41 1313.71 38 1311-73 39 1312.62 44 1313.75 39 1311.76 29 1312.66 44 1313.89 41 ON Suspended Sediment Data 9/28/78 Track 6 (continued) Depth is 59 feet Tim S".Conc Location (ft) Time Sed.Conc Location (ft) Time Sed-Conc Location Cft) EST wq4t N/S E/W EST 09/1 M/5 E/U EST mg/l WS E/U 1313.84 39 1315.03 51 1315.96 41 1313.86 40 1315.06 so 1315.98 39 1313.88 39 1315.12 49 1316.99 39 200 N -399 U 1313.90 37 131S.14 48 1313.93 39 1315.17 so 1313.96 40 1315.19 51 1313.99 42 131S.21 50 1314.04 44 131S.24 47 1314.05 44 1315-27 48 1314.09 46 131S.31 52 1314.12 46 1315.33 S3 1314.14 45 1315-35 52 1314.17 46 1315.36 52 1314.22 46 1315.39 53 1314.25 45 1315.42 56 1314.27 44 1315.46 58 1314.30 46 1315.49 62 1314.32 45 1315.52 64 1314.36 44 1315-55 67 1314.40 46 1315.57 68 IM4.43 48 1315.59 68 1314.4S 48 1315.62- 66 1314.50 so 1315-6S 64 1314.56 49 131S.65 63 1314.60 44 1315.67 60 1314.63 4? 1315.70 58 1314.67 47 1315.70 57 1314.71 48 1315.72 55 1314.72 49 1315.76 55 1314.74 48 1315.77 56 1314.77 47 131S.79 55 1314.79 46 1315.80 54 1314.82 45 131S.84 54 1314.83 45 131S.87 53 1314.87 46 1315-87 52 1314.92 47 1315.91 49 1314.96 47 1315.92 45 131S.09 so 1315.94 42 Suspended Sediment Data 9/28/78 Track 7 Depth is 25 feet Tim Sed.Conc Location (ft) Time Sed.Conc. Location (ft) Time Sed.Conc Location (ft) a EST 09/1 NIS E/W 'EST Mg/l NIS E/W EST. mg/l HIS E/U 1329.80 24 2N N -300 U 1322.03 29 1320.84 24 n2a.v 26 1320.97 25 1322.12 24 1320.91 24 1322.15 24 1320.97 24 1322.17 24 1320.99 24 1322.22 24 1321.03 23 1322.25 23 1321.05 27 1322.29 21 1321.08 24 1322.32 21 1321.12 22 1322.34 23 1321.16 21 1322.37 21 132L.19 21 13?-2.40 21 1321.22 21 1322.44 21 1321.25 21 1322.47 22 1321.28 21 1322.Sl 22 .1321.32 21 1322.56 22 1321-34 21 1322.59 21 1321.37 21 1322.63 21 1321.40 21 1322.66 20 1321.45 21 1322.68 20 1321.49 21 13P-2.71 20 1321.St 21 1322.74 20. 1321.54 21 1322.77 21 1321.58 21 1322.82 21 1321.61 21 1322.86 21 1321.6S 21 1322.89 20 1321-68 21 1323.10 21 1321.72 21 1323.29 29 1321.76 21 1323.34 20 1321.78 22 1323.46 20 1321.82 as 1323.54 21 1321.84 27 1323.68 20 1321.87 25 1323.84 19 1321.96 25 1323.92 19 1321.93' 24 1323.97 21 1321.96 2S 1324.05 21 13al.98 26 1324.11 19 200 N 309 E 1322.01 28 00 SusI nded Sediment Data gr2g/79 Track 8 Depth.13 25 feet Timie Sed.Conc Location (ft) Time Sed.Conc Location (ft) Time Sed.Conc Location (-ft) EST mg/l NIS E/U EST mg/t NIS E/W EST rog/l MIS E/U 1327.57 18 6" N 3" E 1327.78 19 13a7.90 19 1328.07 19 1328.25 19 1328.S7 is 1328.91 20 1329.10 20 1329.47 20 1329.78 20 1330.09 20 1330.S9 at 1339.97 21 1331.32 21 1331.78 21 1332.93 20 1332-37 20 1332.79 20 1332.95 20 1333.37 20 1333.64 20 1334.95 19 1334.41 19 1334.69 19 t334.99 is 133S.21 19 133S.40 is 609 N -300 U SU3pended Sediment bate 9/28/78 Track 9 Depth is 50 feet Time Sed.Conc Location (ft) Time Sad.Conc Location (ft) Time Sed.Conc Location (ft) EST aff/I N/S E/W EST mg/l H/S E/W EST mg/l N/S E/W 1736.50 12 200 N 1736.94 12 1737.26 12 1737.68 11 1738.81 12 0 a 1738.96 16 1739-12 19 1739.1S 16 1739.18 17 1739.24 18 1739.27 is 1739.32 16 1739.36 Is 1739.39 13 1739.55 13 -200 S a 1739.61 Is 1739.67 Is 1739.69 14 1739.85 Is 1739.99 17 1749.08 is 1740.29 13 1749.47 12 1740.62 11 1749.75 11 -400 S .0 Near Bottom Currents in the Lower James and Elizabeth Rivers bv Christopher S. Welch Virginia Institute of Marine Science School of Marine Science College of William and Mary Gloucester Point, Virginia 23062 March, 1981 Near Bottom Currents in the Lower James and Elizabeth Rivers A knowledge of currents in the Lower James and Elizabeth Rivers has been of interest for the longest time to the commercial and military shipping interests. This may be illustrated by the events which led to the historic naval engagement between the USS Monitor and the CSS Virginia in Hampton Roads. A systematic survey of the currents in this region, undertaken as part of a comprehensive regional survey by the US Coast and Geodetic Survey, was reported by Haight, et al. (1930). While comprehensive in areal extent, this survey-, responsive to the needs of port operation, dealt primarily with surface currents in the region of interest for the present study. The 1930 results are further compromised, for the present study, by the substantial alteration of the dredged channels since that time. After the channel was dredged, the Coastand Geodetic Survey again measured the currents, this time at several depths,'in 1951. Between then and now, the construction of the Craney Island Disposal Area again changed the current patterns in the study area. These changes are noted by Neilson and Boule' (1975). The significance (and difficulty) of current measure- ments in the study region is illustrated by noting. that, in 1951, the first technical report produced by the newly formed Chesapeake Bay Institute (Pritchard and Burt, 1951) was titled 202 "An inexpensive and rapid technique for obtaining current pro- files in estuarine waters". This report, an indication of the agenda of the new institution, introduced a biplane current drag, subsequently called the Pritchard drag. In operation, the drag is manually deployed over the side of an anchored. vessel, the current being related to the angle from the vertical caused by the current pulling the drag to the side while a weight tends to return it to the vertical. It is of interest, from the perspective of nearly thirty years, that the qualities of low cost and rapidity of operation were emphasized in the title while those of accuracy and precision were not so emphasized. A study, named Operation Oyster Spat, was quickly initiated using the new device, and the data from station J-17, located in the main channel just to the south of Burwell Bay, have become famous as the prototype mean flow pattern for partially mixed estuaries. Another station from Operation Oyster Spat was located upriver of J-17, at Deep Water Shoal, the upper limit of oyster production in the James. A subsequent study, Operation James River (Shidler and MacIntyre),-was performed 13 years later by VIMS and other cooperating organizations. This study was conducted after the Craney Island Disposal Area had been built, and the cur- rents in the lower'part of the study area were shown. (Neilson and Boule', 1975) to have been shifted to the north by the construction. In contrast to the earlier study by Chesapeake 203 Bay Institute, Operation James River concentrated on-obtaining a wide spatial coverage of the lower James River with short time series rather than long series at a few locations. A further study using current meters in the James River part of the study area was undertaken by the U.S. Army Corps of Engineers in the support of the calibration for the Chesapeake Bay Model. For this study (Ruzecki and Markle, 1974) current meters were placed at several depths at four river transects in the study area: at the mouth of the James, at the upper limit of the Newport News Shipyard, near the downstream part of Bur- well Bay and off Hog Point. Ten stations were occupied,in these transects, the ones at the mouth for a period of 19 days and the others for periods of about four days each. In,total thirty-three current meters were deployed at these stations. Some of the data have been analyzed (Lewis, 1975) at the downriver transects to obtain tidal constituents. In June of 1972, the entire Chesapeake Bay watershed, including the James River, was inundated with rains from tropical storm "Agnes". As part of a massive study to examine the effects of this flooding, current meters were again set in the study area, occupying the transect off of the Shipyard (Jacobson and Fang, 1977) for a period of eight days. From the standpoint of maintenance dredging, the Eliza- beth River is much more important relative to the James River than its areal extent would suggest, for the majority of the Elizabeth has been dredged to a.substantial depth. One result 204 of the channel depth and the short length of the Elizabeth is that the gravitational flow, which results in estuarine circu- lation in longer estuaries with greater fresh water i@iflow, becomes a rapid adjustment of the stratification in the Eliza- beth to that of the James and to rainfall events (Neilsont 1975). Thus, circulation in the Elizabeth River is expected to be primarily tidal, augmented with events of two layer circulation consisting generally as an intrusion of salty water from the James upriver in the Elizabeth along the bottom. As the two layer circulation occurs in distinct events it may or may not be evident in any particular set of current records obtained in the Elizabeth River. Several sets of current data have been obtained in the Elizabeth River over the years. A set of four stations was occupied in 1974 for a period of two and a half days, the stations located in the main stem and each of the three branches of the river. The 12'current meters used in this study were deployed at depth increments of about six feet with the upper- most instrument at a depth of six feet (Cerco and Kuo, unpub- lished ms.). The U.S. Navy has obtained several sets of current meter records in the part of the Elizabeth adjacent to the Norfolk Navy Base. One of these sets (S. Jenkins, Scripps. Institute of Oceanography) resides at the Scripps Institution of Oceanography. Another (Ruzecki and Ayres, 1974). had current meters located near the bottom on both sides of the ship channel of the Elizabeth River close to its junction with the James 205. River for a period of about 20 hours under conditions of low river flow and spring tides. A third-set of current meters was deployed in conjunction with the present investigation near the Craney Island landfill site for'a period of 28 days with meters at de pths of 3, 6, 12 and 15 meters during September and early October of 1978. As these last data have not yet been finally.analyzed, they are not included in the interpre- tation. one of the experimental constraints with current meter measurements is that strings of current meters cannot be placed in shipping channels, because they will be destroyed by the shipping traffic. The string of meters placed in the Eliza- beth for the present study was placed at the edge of the shipping channel, and it was still damaged by shipping. As a result of this constraint, there are few direct measurements of.currents in the middle of shipping channels. The writer knows of only one current transect obtained in the Newport News Channel. That transect has never been published,as it was ancillary to a larger experiment, and the current meters were not ever calibrated. The data do show, however, that the current in the transect reached a local maximum speed (during both flood and ebb) within the dredged channel just below the level of the surrounding river bottom. In both instances, the current speed at this maximum was about the same as that at the surface. 206 Another method of measuring currents, drogued-buoys, has also been employed in the study region with some success. This method does not produce long time series, but it can be applied in the channel areas where current meters are in jeopardy. It is also compatible with a simultaneous description, of currents over a wide area, such as the entrance channel of the Elizabeth River or the breadth of Hampton Roads. Using drogued buoys, surface current data have been obtained within the Elizabeth River and Hampton Roads in several projects associated with sewage effluents, (Neilson and Boule', 1975; Welch and Neilson, 1976); bridge tunnel construction, (Fang, et al., 1972; Fang, 1979); and port facility siting efforts, (Fang, 1975). In the Elizabeth River, the surface data gathered from these various efforts-have been compiled into a single Elizabeth River Circulation Atlas, (Munday 'et Al-i: this report) which segregates surface current patterns by tidal phase and wind velocity classes. Another use of drogued buoys was made in the Elizabeth River directly in support of the present effort. A cross-s ectional velocity estimate was constructed from drogued buoy data in a region crossing and including the main ship channel of the Elizabeth River. This estimate is of significance beyond this project because it is the first synoptic cross sectional current velocity determination which has been made entirely using drogued buoys located.by remote sensing in a concurrently occupied shipping channel. It has been reported as such by Munday, et al (1980) in its context 207 as a new techniaue which is applicable to current determination in busy port areas. A number of current studies have been performed in the region of interest. Even with these studies, little direct evidence exists for formulating estimates of currents near the bottom of dredged channels, the focus of interest for the present study. For this reason, the formulation of the estimate for current speeds at the bottom of dredged channels in the study area will be based partly on indirect measurements and inferences. The remainder of this report is concerned with.these estimates for the Elizabeth River, the Newport News Channel, and the Rocklanding Shoals Channel, the major dredged channels in the study area. Elizabeth.River Current Calculation The Elizabeth River is complex in its geometry, but it also is relatively'short. The National Ocean Survey Tide and Tidal Current Tables show time differences between tidal height and tidal currents as they propagate down the 24 kilometer length of the deep channel. The time of high tide, according to these tables, is within 15 minutes of being simultaneous at all stations, while tidal currents reach slack water about 30 minutes or less after slack water at the river mouth, near. Craney Island. In addition, the typical tidal ranges at all stations are within 10% of those at Sewell's Point,- at the mouth of the Elizabeth River. As all of these time differences are small with respect to the 12.42 hour (745 minute) semi- diurnal tidal period, an estimate of the tidal currents can 208 be made using tidal prism calculations, which are based on the assumption that the water surface in the Elizabeth River is at all times a level surface, implying that slack currents occur simultaneously with extreme tidal heights and that ex- treme tidal heights are simultaneous and equal throughout the. basin. Because of this assumption, the current estimates will be made only in the enclosed part of the Elizabeth River, that portion south of the outer levee of the Craney Island Disposal Area (36055127"N). Under this assumption, the volume of water which passes through any cross-section of the river equals the product of the surface area upriver from that section and the change in water level. If the water levels considered are successive tidal height extremes, the volume is called the intertidal volume. if the intertidal volume of water above a chosen cross section is assumed to be supplied by water moving through the section during the rising and falling tidef a cross-sectional average flow speed can be calculated for the tidal phase (rising or falling,tide). The peak speed averaged over the cross section during a tidal cycle 'is Tr/2 times this average flow speed under the assumption that the speed describes a half-sinusoid between successive times of slack water (or height extremes). Thus, a voldmetric calculation is available which permits calculation of cross-sectional average flow speeds (.and peak speeds) from a consideration of surface areas and cross-sectional areas in 209 a short estuary of complex geometry. This calculation has been used to estimate currents in the Elizabeth River. If a distance scale (x) is defined extending from the head of each tributary and the main course of the river, an incremental surface area dA(x) can be defined so that the total X area upriver of a given point, x , is A(x f 0 dA(x) + Z T 0 0 th where T. is the total surface area of the i tributary entering the river above x If A(x ) is relatively independent of 0 0 water level,corresponding to nearly vertical banks, the total volume of water entering the river above a cross-section at x 0 is A(x )AH, where AH is the change in water level. With the 0 river cross-sectional area at x denoted as C(x ) and the time 0 0 difference between.the two water levels denoted as At, the flow velocity ave raged over the cross section and the time A (x0) AH interval becomes v(x 0)= In our flow calculations, 0 the quantity A(X) is evaluated for a set of chosen cross sectionst C.(x) and is evaluated for each of the intervals between tide At height extremes during the year 1975, an arbitrary year pre- sumed to be typical, the values being grouped and presented as a cumulative frequency curve. The Elizabeth and its tributaries were subdivided into 26 segments according to the scheme used by Cerco and Kuo (unpublished ms.) , and the mean low water areas were measured for each segment. The measurements were made from National Ocean Survey charts 12245 and 12253, which together cover the entire tidal extent of the Elizabeth and its tributaries at a 210 scale of 1:20,000. Because the basin does not possess exten- sive marsh areas*, indeed is substantially bordered by vertical bulkheads, the areas measured were applied to the entire tidal range for current computations. The areas are shown in table 1, and the segmentation s'cheme is shown in figure 1. To calculate tidal heights, tidal predictions from Sewell's Point were gathered for the year 19751 and values of AH/At were.calculated for each tidal cycle, segregated into rising and falling tides. As the two cumulative frequency curves are nearly identical for Sewell's Point, we@present only a single curve in figure 2. Selected percentile values are presented in table 2. The mean value is 3.48.x 10- 3 cm/sec, while the median is 3.40 x 10-3 cm/sec. Mean current speeds for each cross-section are also shown in table 1. The calculated mean cross-sectional values are shown, with other information, on figure 3 as a set of line segments connecting calculated points. Verification of the data can be done with comparison to other work.. The areal measurements are compared with previous work by Cronin (1972). The mean current speeds are verified by comparison with a drogued buoy cross-sectional current determination done specifically for the present effort. In comparing areal measurements of the rivers, allowance must be made for the difference in river mouth locations be- tween Cronin (1972) and Cerco and Kuo (unpublished.ms.). If this is done by using Appendix A in Cronin (1972), and the value for the Lafayett e River is added to that of the Elizabeth Table 1. Measured Segment Areas and Mean Speed Calculation for the Elizabeth River Cumulative Downriver Bounding Mean Current Segment Area Area Cross-Section Area Multiplier Speed (xlo5m2) (xl05m2) (x 103m2) (x 102) (cm/sec) 2 5.84 5.84 0.53 11.01 3.8 3 5.73 11.57 0.43 26.91 9.4 4 5.91 17.48 0.57 30-67 10.7 5 14.02 31.50 0.69 45.65 15.9 6 8.80 40.30 1.79 22-51 7.8 7 8.52 48.82 3.25 15.02 5.2 8 8.18 57.00 3.08 18-51 6.5 9 10.82 67.82 2.52 26.91 9.4 10 9.99 77.81 2.78 27.99 9.8 11 4.96 82.77 4.78 17.32 6.0 12 11.24 141.13* 6.28 22.47 7.8 13 29.03 170.16 11.78 14.44 5.0 14 42.30 271.18* 9.13 29.70 10.4 15 46.54 317.72 10.20 31.15 10.9 16 39.19 415.42* 11.52 36.06 12.6 17 46.88 462.30 14.56 31.75 11.0 E2 19.64 19.64 1.46 13.45 4.7 @E3 16.38 36.02 2.00 18.01 6.3 E4 11.10 47.12 3.52 1j.39 4.7 W2 15.93 15.93 0.84 18.96 6.6 W3 23.06 38.99 1.36 28.67 10.0 W4 19.73 58.72 2.09 28.10 9.8 Ll 17.73 17.73 0.99 17.91 6.2 L2 18.33 36.06 0.69 52.26 18.2 L3 22.45 58.51 0.86 68.03 23.7 Includes tributary contribution 212 37 0OWN HAMPTON ROADS ELIZABETH RIVER 9 NAUTICAL MILES 1 0 1 NAVY PIERS 17 3 16 L2 LAFAYETTE 15 RIVER Ll 1 W4 EASTERN 12 BRANCH E3 E2 2 %W3 WESTERN BRANCH E4 9 8 6 SOUTHERN BRANCH 5 36 045'1@- 4 3 2 76u25'W 760@0,w Figure 1. Segmentation of the Elizabeth River basin for tidal prism calculations (after Cerco and Kuo, unpublished Ms.). 213 100 90 80 4j 70 Q) 60 04 50 4J 4 40 30 20 10 0 4 5 7 8 9 10 11 AH (x 10-3 cm/sec) AT Figure 2. Cumulative rates of average predicted height change over a half tidal cycle at Sewell's Point, Hampton Roads,,Virginia. 214 Table 2. Percentage Points for Predicted Average Height Change Over a Half Tidal Cy cle at Sewell's Point, Hampton Roads, Virginia. Sample Period is 1975. Percentage of Occurrences Less Than Level .1 4.0 .5 4.3 1 4.5 2 4.6 5 4.9 10 5.2 15 5.4 20 5.6 25 5.8 30 6.0 35 6.2 40 6.4 45 6.6 50 6.7 55 6.8 60 7.0 65 7.2 70 7.4 75 7.7 80 8.0 85 8.5 90 8.9 95 9.5 98 9.8 99 10.2 99.9 10.8 t-n Figure 3. Mean current speeds for the Elizabeth River and its tributaries. M: Main Stem, S: Southern Branch, E: Eastern Branch, L: Lafayette River. Dashed lines show connections between tributaries and the main stem. X's and O's are corresponding values for model study (Cerco and Kuo, unpublished ms.). The X's are the values for the main stem, while the O's are labeled by tributary. The point V-Elis the mean value calculated from the drogued buoy study, while C-Ois the estimated time mean value of cross- sectional peak speed used for model comparison. Variation bars show extent of variability due to tidal variability around time mean values. 40 40 30 20 x 100% w w 15 - E Q) x 0 Ln x 80% w F@ b 0-1- a) C) (U 10 - Mean P. cz 9 ca 8 > 80% cz 7 6 10* 5 4 3 35 30 25 20 15 10 5 0 Position (km from mouth) 217 River, the total area for the river from our measurements 5 2 becomes 566.08 x 10 M while that from Cronin (1972) is 5 2 518.8 x 10 M The resulting difference amounts to 8% of our measured value. The estimated accuracy of the present area measurements is 1%, so a real discrepancy exists between the two sets of measurements. A further comparison was made between the transport predicted by the tidal prism measurements and that measured (Munday, et al., 1980) for that purpose on September 19, 1978. The verification measurements were made near the outer boundary of section 16 as defined by Cerco and Kuo Just north of Tanner Point. The resulting interpolated velocity section (fig. 4) was planimetered forareas between each 5 cm/sec isotach neglecting the deep area towards the right of the section, which is part of a berthing area surrounded by piers, and plausibly has little transport. The areas measured are bounded bv the dashed line with the dotted extension, the solid line where there is no dashed line, and the free surface. This measured cross-sectional mean speed was 22.5 cm/sec. To compare with mean speeds shown in figure 3, this value was multiplied by the ratio of mean AH/At to that calculated for the time of the measurements using Sewell's Point tide station observations. It was again corrected for the-time within the tidal cycle (estimated as 105 minutes before high slack water). of the measurements under the assumption of a sinusoidal height variation with time. The resulting mean speed value, 13.3 cm/sec, is' shown in figure 3 and is comparable to the value of 218. 3 f t.) 15 7 f Q 35 5 20 3.0 25 3'0 0 6.1 25 f 0 9.1 0 1 2 CROSS CHANNEL VELOCITY -SCALE I cm sec 12.2 40 ft-) 30 15.2 0 1000 2000 DISTANCE (meters) Figure 4. Synoptic flood tidal velocity cross section using drogued buoys and photogrammetry on September 19, 1978. Section is located within segment 17 looking towards the river mouth. Isotachs have units of cm/sec. @5@@, 5, f t.) -- J'', '0 2@ 219 12.6 cm/sec obtained from tidal prism calculations. The two average cross section currents agree to within 6% forthis verification. This agreement is well within the limits of experimental accuracy. A final comparison is shown in figure 3 between mean current speeds from the tidal prism calculations and speeds calculated from amplitude values derived from the current meter measurements of Cerco and Kuo. These latter are shown as xf s on figure 3 for the main stem and southern branch of the Elizabeth River, and as circled points for the other tributaries. Comparing the two sets of values,.agreement is relatively close (<15%) in the middle part of the main and southern branch seg- ment, but it is reduced towards the mouth and in the smaller tributaries, the Cerco and Kuo values being systematically 4) higher than the tidal prism calculations by from 20 to 100%. Because these values were obtained by current meters located in or near the central channel, the hypothesis was formulated that the current meter data were obtained in a rapidly flowing part of the river and that the average speed was smaller than the measured speed in places where the channel occupied a relatively small part of the cross section. To test this hypothesis, the mean speed from the prism measurements for section 16 was multiplied by the peak-to-mean speed ratio from the cross section in figure 4, (37.5 cm-sec- 1/22.5 cm-sec- 1. 1.67). The resulting value, 20.8 cm/sec, was within 2% of the mean value of 20.4 obtained from Cerco and Kuo's results. 220 This supports the hypothesis that the current meter values were associated with high velocity cores in the cross-sectional flow. If the flow pattern in figure 4 is typical, it is the high speed core value which is most appropriate'to the near- bottom part of the channels, where maintenance dredging is needed. This finding is similar to that obtained from the current profile from the Newport News Channel disclosed earlier. For the Elizabeth River, then, the speed values associated with the Cerco and Kuo current meter results, denoted by X's in figure 3, are our best estimate for values of currents in deep channels for which maintenance dredging is required. These values are mean values, and the variability due to varying astronomical tides is given by the range bars in figure 3. Newport News Ship Channel Current Calculation The method used for estimating currents in the Eliza- beth River, while applicable to small enclosed basins with little freshwater flow, is not suitable for calculations in the main stem channels of the James River. The major reasons are that the tidal propagation in the main stem of the James has to a large extent the character of a propagating wave, and so the tidal prism estimating technique must be modified. Also, the James has current associated with river flow and an estuarine circulation which is not accounted for in the tidal prism method. On the other hand, the Newport News Ship channel has a relatively 221 uniform width and project depth along its length, so currents can be plausibly supposed more nearly uniform along its length than in a confined port area. Accordingly, it seems reasonable to apply data from a small number of current meters to the entire length of the Newport News Ship Channel, while such generalization is not supported in the Elizabeth. The basis for the estimate in Newport News Ship Channel is current meter data. Current meters are sensitive to the vector sum of currents from all causes. If we have available time as an independen ,,t variable, a current record can be decomposed into a mean value, representing river flow, estuarine circulation and the mean of weather events during the period of record, an oscillatory tidal signal, representing the major,current component in the region of interest, and a time-varying flow due to storm surges, local wind response and other weather related events as Kiley (1980) has done in the York River. Under these conditions, the best estimate of mean currents is .the mean non-tidal value for the record. Also, the best estimate of variability from non-tidal currents is the non- tidal variability of the record. The tidal variability is obtainable from the predictions or an astronomical tidal forcing function, and measured tidal variability can be biased to provide an improvement over the record data itself by taking the regularity of the tides into account. Currents from short term VIMS moorings have.been treated this way by Lewis (1974), and Boon and Kiley (1978) report another method using least 222 squares fits for longer period data. Both of these methods are useful for segregating thetotal time series into tidal and non-tidal parts, with determinations of astronomical tidal constituents as at least part of their result. Both of these approaches require computers to be practically. implemented, although one (Boon and Kiley, 1978) can be per- formed with a calculator and a special set of auxiliary tables. Both of these methods also require a regularly spaced time series of current measurements as input. Another analysis method to estimate mean currents variability has been developed for the present estimate for which a hand calculator and tidal,height tables are sufficient, particularly if the estimate to be made is near a primary tidal station, such as,that at Sewell's Point. For this method, the times and speeds of current maxima are obtained from the record, and corresponding values for AH/At are calculated from the tide tables. The current values are then linearly re- gressed on the AH/At values, and the mean value of peak current is obtained from the long term mean value of AH/At, already developed for Sewell's Point in the Elizabeth River calculation. In the present instance, only one of the previously' noted current studies, that of the Coast and Geodetic Survey in 1969 (DeRycke, unpublished data), actually deployed current meters within the deep channel of the Newport News Ship Channel. Two of these stations were located in the channel itself, one (station 2) at the eastern end and one (station 3) at the channel 223 edge in mid channel. These were both occupied for about 1.5 days with Roberts Radio current meters, with occasional com- parison readings made using drogued buoys.- The times, speeds and directions for the flood and ebb current peaks obtained from this data are shown in Appendix 1 along with corresponding values of AH/At (in feet/minute, most easily obtained from the Tide Tables). These data, segregated into ebb and flood direc tions, were then analyzed for a regression relation of the form Speed (knots) = B0 + B 1 x AH/At (feet/minute The standard errors fro m the relation (table 3) were calcu- lated as estimates of random variability with tidal variability being obtainable from the variation bars of figure 3. The mean value of speed was obtained by evaluating the regression equation for AH/At 6.86 x 10- 3 ft/min, the mean value for Sewell's Point. Finally, these data are increased by a factor of 1.53, to correct a systematic bias in C&GS data reported in Fang (1979) and converted to cm/sec for consiste ncy with the Elizabeth River estimates. The mean current'estimates for use in the sediment plume model are obtained by dividing by 7/2 @ to produce mean values throughout the tidal phase (ebb or flood). The mean values of peak speeds during a tidal cycle are shown in table 3 as "corrected mean" and "corrected standard error", with the estimates for mean value for use in the sediment plume model listed as "Tidal Phase Mean". 224 Table 3. Results of Current Calculations in Newport News Ship Channel 2 Flood .01 .10 .14 55 11 35 2 Ebb .09 .10 .15 61 12 39 3 Flood .09 .11 .17 66 13 42 3 Ebb -.32 .15 .13 56 10 36 In interpretation, the values from station 3 are probably more representative of the dredged channel than those from station 2. The former have their directions oriented parallel to the dredged channel while the latter are oriented in the direction of the natural entrance channel to Hampton Roads, 45 from the dredged channel. Rocklanding Shoal Channel The third and final channel in the area under con- sideration, Rocklanding Shoal Channel, has the shape of a dog-leg on a chart. The channel is about 6 nautical miles long, with the dog-leg section comprising the southern 25% of the length. Passing the oyster grounds of Burwell Bay it is maintained at a depth of 211/2 feet below mean low water. Rocklanding Shoal Channel shares the tidal flow of the 225 James with another natural channel in Burwell Bay having a controllin g depth of 11 feet. According to.Nichols (1972) more tidal flow passes through Rocklanding Shoal Channel during flood tide than during ebb, classifying it as a flood channel. Along its length, Rocklanding Shoal Channel.passes by numerous indentations and side channels with nearly the project depth, in contrast to the other channels described in this study, which are well defined cuts through shallow reaches. In estimating'the currents in Rocklanding Shoals Channel, cur rent meter data obtained during operation James River (Shidler and MacIntyre, 1967) are used. Current stations with measurements obtained each half hour for a period of more than three days were obtained at three locations within the channel during this study. The locations are near the northern and southern ends of the primary section and in the center of the dog-leg. Currents at the two stations in the main part of the channel were measured with a Roberts Radio current meter, with a Hydro Products meter used for surface currents. At the dog-leg station, a current pole was used for surface currents? and a Pritchard drag was used for subsurface currents with direction being determined with the ship's compass or a hand- held Weems magnetic compass. The currents at these stations each have a distinct character, so it is likelythat no single value of.current can accurately describe the entire channel. Because the available stations span thellength of the channel, it is plausible that they represent the extreme conditions and that 'appropriate values 226 for the intermediate points can be obtained through linear interpolation from the available data. In the dog-leg section, the direction for ebb currents .has a bimodal distribution, the bottom current frequently following the channel at 900T and the upper currents following 0 the trend of the river at 130 T, but the pattern of occurrence is not regular. At the southern end of the major leg, the .record shows ebb currents slightly dominating over flood currents. Perhaps more important, the flood currents have little relation to the corresponding AH/At's, the correlation coefficient being only .16 with 8 samples. In contrast, ebb currents, after deletion of a weather-associated outlier, have a correlation of .70 with AH/At. It may be that the division of flood currents between Rocklanding Shoals Channel and the alternate channel through Burwell Bay is highly variable and responsive to other factors, such as transverse wind stress. From the available data, the ebb curre nts in the southern part of the channel tend, with marginal significance, to predominate over flood currents. At the northern end of the channel, the opposite condition is:found with flood currents predominating over ebb currents substantially. Both flood and ebb.currents are correlated (at the 90% significance level) with AH/At's at the northern end. Thus, the northern end of Rocklanding Shoals Channel is a definite flood channel, and the southern end is a slight ebb channel. This is consistent with the data of Nichols (1972) who characterized the channel as a whole as 227 a flood channel from data taken slightly north of its,center. The change in measured predominance may be due to the sharp bend which must.be taken by entering water to pass by the current stations at both ends of the channel on the appropriate tidal phase. 0 For five of the six possibilities, estimates can be made for the average current speeds to be found in the channel for average AH/At. These. .are shown in table 4. For.the. sixth case, the estimate is@simply of the available observations, with the standard, deviation of the observations reported in- stead of the.standard-error of the regression. These values areshown in parentheses to emphasize the difference in deriv- ation between them and the rest of the values. In general, anincrease in current speeds is found in the bottom of the dredged channels as one progresses up the.James Rivet withinthe study area. This increase is partly due to a decrease in cross-section area progressing upstream along with a smaller decrease in tidal flux. This interpre- tation is a contrast to that of Nichols (1972), who indicates that bottom currents at.Rocklanding Shoal are substantially smaller than those near Newport News. The difference may be related to the difference between field data used in the present ,estimate and hydraulic model data used in the estimate of Nichols (1972). 46 tXjZ t7lZ tIj Cn tZj En 0 0 @50 :j0 :j0 0 0 a Qj LQ r@ ft rt I I (D Station LO LQ m t:r ty Ur H Phase v 0 17 0 v 0 0 0 0 Qj Oj B0 0) Ln C) D. (cm/sec) '0 bi C) 110 CO CO 0) B Fj cm/sec CO 10. w m 3 f t/minxlO .D. Lq rj Ln C:) 00 Standard Er L" -Ij CO CD tQ (cm/sec) Ln P:- Mean 0 J@- Ln w tIj ON .(cm/sec) Tidal Phase Ln Ln %.0 0) N) Mean (cm/sec) Corrected T w Ln P.- w 0.- D.- %@O w ID. Ili N) Phase Mean (cm/sec) 229 REFERENCES Boon, J.D. III and K. P. Kiley, 1978, Harmonic analysis and tidal prediction by the method of least squares, Special Report No. 186 in Applied Marine Science and Ocean Engineeringi Virginia Institute of Marine Science, 49 pp. Cerco, Carl F. and A. Y. Kuo, unpublished ms, Real-time water quality model of the Elizabeth River system, Special Report No. 215 in Applied Marine Science and Ocean Engineering, Virginia Institute of Marine Science. Cronin, William B.1, 1971, Volumetric, areal, and tidal statistics of the Chesapeake Bay estuary and its tributaries, Special Report 20, ref. 71-2, Chesapeake Bay Institute, The Johns Hopkins University, 135 pp. DeRycke, R. J., 1969, Current meter logs from USC & GSS Ferrel (ASV-92). Fang, C. S., B. J. Neilson, A. Y. Kuo, R. J. Byrne and C. S. Welch, 1972, Physical and geological'studies of the proposed bridge-tunnel crossing of Hampton Roads near Craney Island, Special Report in Applied Marine Science and Ocean Engineering No. 24, Virginia Institute of marine Science, 42 pp. Fang, C. S., project engineer, 1975, A surface circulation study in middle Elizabeth River, A Report to NUS Corporation, 66 pp. + appendices. Fang, C. S., principal investigator, 1979, James River hydraulic model.study with respect to the proposed third bridge-tunnel causeway in Hampton Roads, Special Report in Applied Marine Science and Ocean Engineering No. 212, 159 pp. Haight, J. J., et al., 1930, Tides and Currents in Chesapeake Bay and Tributaries, USCGS Special Publication 162, 143 pp. Jacobso n, J. P. and C. S. Fang, 1977, Flood wave-tide interaction on the James River during the Agnes Flood, pp. 104-117@ in The Effects of Tropical Storm Agnes on the Chesapeake. f-ay Estuarine System, Chesapeake Research Consortium Publication No. 54. 230 Kiley, Kevin P., 1980, The Relationship between wind and current in the York River estuary, Virginia, April 1973, unpublished M.S. Thesis, School of Marine Science, College of William and Mary, 195 pp. .Lewis, J. K., 1975, The analysis of short term tidal data, M.S. thesis presented to the School of Marine Science, College of William and Mary, 104 pp. Munday, John C.11 Jr., C. S. Welch and H. H. Gordon, Estuarine circulation from dye-buoy photogramm6try, 1980, pp. 417-428 in Proceedings of the Ports' 80 Specialty Conference, Norfolk, Virginia, American Society of Civil Engineers. Munday, J. C., H. H.%Gotdon and C. J. Alston, 1980, Elizabeth River Circulation Atlas, in A study [email protected] effects in Hampton Roads, Virginial' VIMS, 1981. Neilson, Bruce J." 1975, A water quality study of the Elizabeth River: The effects of the,Army Base and Lambert Point STP effluents, ISpecial Report No.. 75 in Applied Marine Science and Ocean Engineering, Virginia Institute of Marine Science, 133 pp.. Neilson, B. J. and M. B6ule, 1975, An analysis of currents and circulation in Hampton Roadsl Virginia, Vol. 2 in Studies for a Proposed Nansemond River Sewage Treatment Plant, A Report to McGaughy, Marshall & McMillan-Hazen and Sawy Ier: A Joint.Venture, 98 pp. Nichols, M. M., 1972, Sediments of the James River Estuary, Virginia, The Geological Society of America Memoir/33, 43 pp. Pritchard, D. W. and W. V. Burt, 1951, An inexpensive and rapid technique for obtaining current profiles in estuarine waters, Chesapeake Bay Institute, The Johns Hopkins University, 13 pp. Ruzecki, E.,P. and R. Ayres., 1974, Suspended sediments near Pier 12, Norfolk Navy Base on 26 June and 15 September, 1973, Data Report No. 11, Virginia Institute of Marine Science, 9 pp + appendix. Ruzecki, E. P. and T. Markle, 1974, A report on the prototype data collected in the James River, Special Report Number 84 in Applied marine Science and Ocean Engineering, Virginia Institute of Marine Science, 34 pp. Shidler, J. K. and W. G. MacIntyre, 1967, Hydrographic data collection for "Operation James River-1964", Data Report No. 5, Virginia Institute of Marine Science, 455 pp. 231 Welch, Christopher and Bruce J. Neilson, 1976, "Fine scale circulation near 'Foxtrot' in Hampton Roads, Virginia. An addendum to "Oceanographic,Water Quality & Modeling Studies for the Outfall from a Proposed Nansemond Waste Water Treatment Plant, A Report to McGaughy, Marshall & MacMillan-Hazen & Sawyer: A Joint Venture, Virginia Institute of Marine Science, Gloucester Point, Va., 23062, 36 pp. 232 Appendix 1. Times and Speeds of Maximum Currents in Newport News Channel During U.S. Coast and Geodetic Survey Observations, 1969. Station: 2 Time Meridian: 75 0W Latitude: 36-57'28"N Observer: R. J. DeRycke Longitude: 76 021122"W USC&GSS'Ferrel (ASV-92) Depth: 401 Date Time Speed Direction AH/AT (EST) (Kt) (OT Towards) (xlo-3ft/min) 1/13/69 2055 -0.4 055 -5.7 1/14/69 0300 +0.7 205 +7.0 1/14/69. 1000 -0.8 035 -6.7 1/14/69 1550 +0'.6 215 +5.5 1/14/69 2245 -0.7 025 -6.0 1/15/69 0355 +0.8 220 +9.2 1/15/69 1015 -0.9 030 -7.4 1/15/69 1705 +0.6 220 +5.9 1/15/69 2220 -0.7 050 -6.7 1/16/69 0505 +0.8 220 +8.3 1/16/69 1215 -0.8 030 -8.2 1/16/69 .1820 +0.8 235 +7.1 1/16/69 2355 -0.7 040 -7.8 1/17/69 0635 +0.9 210 +9.1 1/17/69 1255 -0.9 030 -8.9 1/17/69 1845 +0.7 225 +7.6 1/18/69 0055 -0.7 050 -7.9 1/18/69 0740 +1.1 220 +9.4 1/18/69 1335 -0.7 040 -9.1 1/18/69 1935 +0.5 230 +8.1 1/19/69 0155 -0.8 050 -8.5 1/19/69 0815 +1.1 220 +9.6 1/19/69 1425 -0.8 050 -9.3 1/19/69 2055 +1.0 240 +8.2 1/20/69 0235 -0.9 .045 -8.5 1/20/69 0930 +1.1 240 +9.3 1/20/69 1535 -1.0 050 -9.0 1/20/69 2210 +1.0 210 +8.2 1/21/69 0330 -1.0 035 -8.2 1/21/69 1055 +1.0 215 +8.5 1/21/69 1610 -1.1 045 -8.2 1/21/69 2315 +0.6 220 +7.9 1/22/69 0425 -1.0 035 -7.5 1/22/69 1125 +0.8 220 +7.7 1/22/69 1635 -1.1 035 -7.4 1/22/69 2335 +0.6 215 +7.1 1/23/69 0520 -0.8 050 -6.7 1/23/69 1145 +0.9 215 +6.4 1/23/69 1720 -0.9 040 -6.5 1/24/69 0020 +1.0 225 +6.8 Appendix 1 (Cont1d) Station 2 Date Time Speed Direction AH/AT (EST) (Kt) (OT Towards) (xlo-3ft/min) 1/24/69 0605 -0.9 040 -6 -1 1/24/69 1240 +0.7 230 +5.4 1/24/69 1855 -0.8 045 -5.6 1/25/69 0005 -+0.8 240 +6.2 1/25/69 0655 -0.6 060 -5.6 1/25/69 1305. +0.4 260 +4.5 1/25/69 1920 -0.7 050 -4 -8 1/26/69 0110 +0.5 245 +5.6 1/26/69 1000 -Q..3 040 -4.9 1/26/69 1435 210 +4 *0 1/26/69 2115 -0.5 060 -4.4 1/27/69 0205 +0.5 250 +5.2 1/27/69 0745 -0.5 045 -4.9 1/27/69 1455 +0.5 220 +4.0 1/27/69 2130. -0.4 040 -4.4 1/28/69 0250 +0.6 220 +5.2 1/28/69 1055 -0.5 030' -4.9 1/28/69 1655 +0.4 255 +4.0 1/28/69 2155 -0.5 060 -4.5 1/29/69 0455 +0.5 245 +5.8 1/29/69 1150 -0.7 060 -5.4 1/29/69 1645 .+0.6 215 +4.4 1/29/69 2225 -0.4 035 -4.7 1/30/69 0405 +0.5 230 +6.1 End of Data iSpeed from drogued buoy. Roberts Radio current meter' readings are erratic and low. 234 Appendix 1 (Cont'd) 0 Station: 3 0 Time Meridian: 75 W Latitude: 36 57.31N Observer: R. J. DeRycke Longitude: 76022.91W, USC&GSS Ferrel (ASV-92), Depth: 40.! Roberts Radio Current Meter Date Time Speed Direction AH/AT (EST) (Kt) .(OT Towards) (xlo-3ft/min) 1/14/69 1600 +0.7 250 1/14/69 2130 -0.6 .090 -6.0 1/15/69 0435 +1.1 260 +9.2 1/15/69 1115 -0.7 070 -7,4 1/15/69 1705 .+0.8 1102 +5.9 1/15/69 2245 .-0.8 2952 -6.7 1/16/69 0520 +1.1 1202 +8.3 1/16/69, 1245 -1.0 80 -8.2 1/16/69 1745 +0.9 260 +7.1 1/17/69 0010 -0.9. 075 -7.8 1/17/69 0615 .+1.4 275 +9.1 1/17/69 1305, -1.1 080 -8.9 1/17/69 1845 +0.9 260 +7.6 1/18/69 .0045 -0.9 080 -7.9 1/18/69 0710. +1.3 270 +9.4 1/18/69 1400 -1.0 075 -9.1 1/18/69 1525 +0.9 270 +8.1 1/19/69 0140 -0.9 075 -8.5 1/19/69 0750 +1.2- 265 +9.6 1/19/69 1415 -1.0 080 -9.3 1/19/69 2030 +0.7 270 +8.2 1/20/69 0255 -0.7 080, -8.5 1/20/69 0905 +1.1 270 +9.3 1/20/69 1600 -0.9 065 -9.0 1/20/69 2130 +1.0 295 +8.2 1/21/69 0330 -1.0 065 -8.2 1/21/69 1020 +0.9 290 +8.5 .1/21/69 1645 -0.9 80 -8.2 1/21/69 2240 +0.7 270 +7.9 1/22/69 0410 -0.8 070 -7.5 1/22/69 1045 +0.9 280 +7.7 1/22/69 1620 -0.9 080 -7.4 1/22/69 2315 +0.7 275 +7.1 1/23/69 0540 -0.8 070 -6.7 1/23/69 1100 +0.8. 270' +6.4 1/23/69 1710 -0.9 070 -6.5 2Readings are in.wrong direction-suspect instrument malfunction. lRaw dat.a,indication switches from 040 to 270 with little change in speed. Instrument malfunction is plausible. Appendix 1 (Cont'd) 235 Station 3 Date Time Speed Direction AH/AT (EST) (Kt) (.OT Towards) (xjo@3ft/min) 1/23/69 2400 +0.7 060 +6.8 1/24/69 0615 -0.8 065 -6.1 1/24/69 1230 +0.9 240 +5.4 1/24/69 1740 -0.7 27 02 -5.6 1/25/69 0 0 35 +1.0 270 +6.2 1/25/69 0605 -0.6 27 02 -5.6 1/25/69 1255 +0.6 0852 +4.5 1/25/69 1935 -0.4 080 -4.8 1/26/69 0110 +0.8 0802 +5.6 1/26/69 0815 -0.2 085 -4.9 1/26/69 1335. +0.2 0852 +4.0 1/27/69 1505 .+0.5 260 +4.0 1/27/69 2130 090 -4.4 1/28/69 0305 +0.9 265 +5.2 1020 -0.5 080 -4.9 1/28/69 1625 +0.5 270 +4.0 1/28/69 2200 -0.2 90 -4.5 1/29/69 0430 255 +5.8 1/29/69 0935 -0.3 080 -5.4 End of Data 2Readings are in wrong direction-suspect instrument malfunction. ELIZABETH RIVER SURFACE CIRCULATION ATLAS John C. Munday Jr. 0 Hayden H. Gordon Charles J. Alston Remote Sensing Center Virginia Institute of Marine Science School of Marine Science College of William and Mary Gloucester Point, Virginia 23062 1977; Revised 1980 236 @ELIZABETH RIVER SURFACE CIRCULATION ATLAS Descriptio The Elizabeth River Surface Circulation Atlas is a compendium of maps which detail the surface circulation throughout the main branch of the Elizabeth River, in the port of Hampton Roads, Virginia. Data for the Atlas maps were obtained directly from field experiments using Remote Sensing-and dye-emitting low-windage surface drogues. The maps show surface Lagrangian trajectories under various combinations of wind and tide. The Atlas is not intended to duplicate NOAA tidal current tables, but rather to supplement the tables with empirical trajectory data at increased spatial resolution. Knowledge of surface currents under different.tide and wind conditions en- ables a user to predict the movement of floating debris, such as oil spills, within the Elizabeth River Basin. The Atlas is based on the fact.that motion of surface water is a product of tidal flow and local winds, and is repeatable under similar conditions. The user obtains readily-available local wind and predicted tidal data, and finds within the Atlas the maps referring to the same conditions. With the trajectories on the maps, the user may move along a trajectory forward in time to find possible future positions, or backward to identify possible earlier positions. The Atlas was designed to be used by planners and managers charged with decision-making and regulation in the Hampton Roads port region. Within this region, the Elizabeth River Basin was chosen for development of a circu- lation atlas, because of the Basin's large volume of ship traffic,. industrial, and waste treatment plants, oil and coal handling facilities, and military and civilian port activities. Immediate applications include: prediction of oil slick movement, to permit containment of a spill before serious environ- mental damage occurs; 'hindsight' prediction, to identify a possible source for a spill; and sewage and industrial outfall siting, with consideration for all the various wind and tide combinations. The Atlas is arranged in leaves to allow future revisions in response to specific user needs. Future generations of the Atlas will include data from new field studies, filling in data gaps in the Condition Matrix. One possible modification would be the addition of a grid coordinate system superimposed on the Atlas maps for orientation. As the data base becomes more complete, circulation information could be referenced to in- dividual grid squares for tide and wind combinations, extending the useful- ness of the Atlas to all locations in the Basin. A second possibility is to include*circulation anomalies such as foam lines and convergence zones on the maps. These, of course, significantly modify the surface circula- tion by trapping and concentrating surface material under certain tidal phases. A third possibility is the addition of maps showing subsurface trajectories. Such data can be obtained using Remote Sensing techniques developed by Munday, Welch, and Gordon (1980, Ports 80 Conference, ASCE, p. 417-428). 237 Revisions will be contingent upon user experience with the Atlas and upon future needs. Due to the flexibility of the Atlas design, accommoda- tions to user needs could be undertaken with a minimum of expense, effort, and time. New current data can be obtained and incorporated easily because the Atlas is prepared using semi-automated photogrammetric and computer plotting techniques. Instructions The surface circulation maps are keyed to wind data from the National Weather Service Office at Norfolk Regional Airport, and to NOAA Tide Tables for predicted high and low water at Sewells Point (Hampton Roads). The following steps are taken to locate the proper map: 1. Using the NOAA Tide Tables, find the times of predicted low and high tide at Sewells Point (Hampton Roads) which bracket the time of interest, 2. Call the National Weather Service Office in Norfolk (853-0553) and request the current and previous (2 to 3 hours) wind velocities, 3. Using the Condition Matrix, locate one of the sixteen bins appropriate for the tide phase.and wind direction from Steps 1 and 2. Within the bin locate the wind speed rec- tangle corresponding to the actual speed from Step 2, and 4. The number(s) indicate the map number(s) which contain the specific circulation data of interest. On each map are surface drogue positions plotted every 15 minutes, with the initial release position depicted by a * symbol. On the lower right corner is a tide curve (high tide above the horizontal line, low tide below) showing the span of the experiment within a tide cycle. Dots along the horizontal line indicate hours after drogue release. Wind speed and direction are illustrated on each map with an arrow referenced to the north arrow (0 to 5 knots, short arrow; 6 to 15 knots, medium ar- row; greater than 15 knots, wind arrow same length as north arrow). 238 CONDITION MATRIX WIND SPEED (KT, > 10 H 5,8 .6-15 F A L L I N G > 15 T 2,3 4,7 5,6,8 6-15 D, E 0-5 P. H A > 15 s E L 2,3,11 9 6 6-15 R 1 0-5 s N G > 15 12 9 6-15 0-5 NE SE SW NW WIND DIRECTION .239 Sample Tide Curve HIGH HIGH TIDE TIDE r EXPERIME T START 4d@ EXP. 0 0 LOW TIDE Example ftpothetical) Suppose me wishes to know surface circulation west of Tamer Point in the Elizabeth River at 1200 an a particular day. By consulting the NOAA Tide Tables, time of high tide is found to be 0930 and low tide 1500. A call to the Norfolk Weather Bureau shows winds to be 2000 at 10 gusting to 15 knots. Checking the Condition Matrix for a tide phase between high (H) and low (L), wind direction SW, and speed 6 to 15 knots reveals maps number 4 and 7 are appropriate. A brief review of the wind and tide information on both maps tends to favor map 4 which begins earlier in the tide cycle and has winds nearer 2000. Drogue tracks show a well-defined ebb flow. Lafayette River Willoughby Bay Sewells Pt. Tanner Pt. J cr. ,77 cc Ln r- CNJ ELIZABETH I cr CIO ED CD Cc cc LLj CD Craney island 4: Disposal Area 1 1: cc-. i- LL@ L-- cr co 17 Ui E)-- '@U@ cc- Lo C\i -:I, cr z m CD CD cc cc LL-i cl: LLJ -i m Cc LD _r_ LLJ IK HHGIPLTR-H.GDRDON-MV11 ELIZABETH RIVER BASIN 020277 AM R T f HHGIPLTH-H.GDRDON-MVII ELIZRBETH RIVER BRSIN 020277 RM R 3D WID, HHGlPLTA-H.GORDON-MV11 ELIZABETH RIVER BASIN 020377 AM R HHGiFLTR-H.GORDON-MV11 ELIZHBETH RIVER BRSIN 020777 RM 9 9)F 4---a HHGIPL'FR-H.GORDON-MVII ELIZHBETH RIVER BRSIN 020777 PM R @A ON HHGlPLTR-H.GORDON-MVll ELIZABETH 91VER BASIN 020977 PM R HHGIPLTR-H.GORDON-MV11 ELIZABETH RIVER BASIN 021077 PH R @px HHGIPLTH-H.GORDON-MV11 ELIZABETH 911VER BASIN 021177 AM 9 Z7 HHGIPLTR-H.GORDON-MVII ELIZABETH RIVER BASIN 0211.77 PM R "MIL HHGiPLTR-H.GORDON-MV11 ELIZABETH RIVER BASIN 0215?7 AM R 00--w HHGIPLTH-H.GOBDON-MV11 ELIZABETH RIVER BASIN 021577 PM R D )r 0 0 0 0 0 DREDGING EFFECTS 0 0 0 0 0 0 THE EFFECTS OF DREDGING IMPACTS ON WATER QUALITY AND ESTUARINE ORGANISMS: A LITERATURE REVIEW by Walter I. Priest, III Virginia Institute of Marine Science School of Marine Science College of William and Mary Gloucester Point, Virginia 23062 March 1981 240 Introduction The primary purpose of this section is to evaluate the effects of total suspended solids (TSS*) levels normally generated by hydraulic cutterhead and clamshell dredges where a confined disposal site is utilized. The emphasis of this review will be on the sublethal and lethal effects of increased TSS concentrations on various estuarine organisms. There will also be a limited treatment of the effects of dredging on other water quality parameters whenever it is applicable to the types of dredging activities being considered in this*repo rt. This report will be divided into two parts. The first will discuss the impacts of non-open water disposal hydraulic cutterhead and clamshell dredging on water quality. The second will present available data from the literature on the effects of TSS on specific estuarine organisms. The literature on the effects of dredging, spoil disposal and suspended sediments on water quality and aquatic organisms has been very ably reviewed and summarized by a number of workers. For a more detailed analysis than is presented here Bouma (1976), Morton (1977), Stern and Stickle (1978), Allen and Hardy (1980), Saila (1980), and the Corps of Engineers Dredged Material Research Program Snythesis Report Series are suggested. Water Quality Aspects The most obvious impact of dredging on water quality is the increase in suspended solids (turbidity) created by the disturbance of the bottom sediments. Despite the extensive research on dredging impacts very little has concentrated on the dredge cutterhead or clamshell as a source of suspended solids. Most of the information available deals with levels of TSS generated at the pipeline or barge disposal site where levels in grams to tens of grams per liter have been observed (Chesapeake Biological Laboratory*,, 1970 and May, 1973). Documentation of the levels of suspended solids created 241 by the dredge itself are very few. The San Francisco Bay Maintenance Dredging EIS, 19751cited from Williamson and Nelson (1977) reported near field levels of TSS from removal operations of 43-70 mg/l for a pipeline, 12-282 mg/l for a clamshell and 74-871 mg/l for a.hopper dredge. After reviewing the available literatureBarnard (1978) made the following comments on the general ranges of suspended solids created by different types of dredges. Clamshell dredges usually produce a plume of suspended solids 300 m downstream on the surface and 500 m downstream near the bottom. They produce a maximum TSS concentration of approximately 500 mg/l while the average water column concentration will be about 100 mg/l. Cutterhead dredges normally produce a suspended solid plume near the bottom of a few 100's mg/l for a few hundred meters downcurrent. Hopper dredging without overflow will generate suspended solids in the range of a few grams/liter adjacent to the dragheads. Wakeman et al (no date) cited from San Francisco COE (1975) reported a reduction of light transmission of approximately 4% below background levels adjacent to a cutterhedd dredge. They also reported highly variable turbidity values for a clamshell dredge. These values ranged up to 26% reduction in light transmission below background levels. Boon and Byrne (1975) in a monitoring report on a dredging operation on Hampton Bar reported typical surface plume TSS concentration of 20-40 mg/l during maximum current conditions. Concentrations within 400 yds of the hydraulic dredge were 50 mg/l and higher. A visible plume approximately 400 x 4000 yds was produced during flood tide. Background TSS levels were 5-15 mg/l. Boon and Thomas (1975) in a report on dredging operations associated with the construction of the second Hampton Roads Bridge.Tunnel reported TSS concentrations of 15-30 mg/l in the surface plume of a hydraulic dredge .242 at distances of less than 1000 ft. Background levels were 3-9 mg/l. They also recorded natural bottom TSS levels of 120 mg/l over the existing tunnel during maximum-tidal current velocity. The issue of dissolved oxygen (D.O.) reduction as'a result of dredging is also clouded by the fact that most rep orts refer to D.O. reductions during the-open-water disposal of the dredged material. Even in this instance the reduction of D.O. has generally been relatively small except in bottom water density flows and of a relatively short, duration (CBL, 1970; COE, 1976; Barnard, 1978). Near-bottom D.O. levels may be less than 2 mg/l near the discharge pipe during open-water disposal (Barnard, 1978). However, Brown and Clark (1968) did report D.O. reductions from 16% to'83% below th e expected minimum in the Arthur Kill between Staten Island, N.Y. and New Jersey during dredging operations. The usual method of dredging was clamshell and hopper barge which was dumped at sea. They described the bottom sediments as containing "accumulations of waste discharges that are deposited continuously. The bottom, which is characterized by a black, soft, oily silt, emanates odors of chemicals, oils, and hydrogen sulfide.". May (1973) reported substantial D.O. reduction at the discharge pipe and in bottom density flows out to 1200 feet from the discharge during open water disposal. Wakeman et al (no date) cited from San-Fran cisco COE (1975) reported a D.O. reduction of less than I ppm, uniform with depth, adjacent to a cutterhead dredge. The reductions around the clamshell dredging were again variable with average reduction being approximately 2 ppm. Some increases in D.O. were also n oted, probably caused by the agitation of the water column by the bucket. The background surface D.O. was 8-9 mg/l. Observations by th e JBF Scientific Corp. in San Francisco COE*(1975) showed an aeration of surface waters by a clamshell dredge and a D.O. 243 increase in bottom waters of approximately 3 ppm. They postulated that an upwelling was created by using the 18 cu. yd. bucket, drawing highly oxygenated water into the plume. The literature reviewed for this report did not contain any information on the release of nutrients, heavy metals and pesticides by dredging per se. All mention of this effect was either associated with open-water disposal or the information related to both dredging and disposal operations with no distinction in the data being made. The material reviewed on open-water disposal operations did report that releases over background of manganese, ammonium nitrogen,-orthophosphate; and reactive silica can occur for short periods of time (Barnard, 1978). Burks and Engler (1978)'reported that releases of short duration of chlorinated pesticides, PCBI s and ammonia can occur when their levels in the sediment are elevated. They also reported that heavy metals can be released under very specific conditions of pH and oxidation-reduction potential. These conditions are usually not found during typical open-water disposal operations, however. The nature and extent of any nutrient and/or pollutant release and its resultant impact is dependent upon a number of site specific characteristics. including: concentration in the sediment, amount of organic and fine grained material in the sediment, pH, oxidation-reduction potential and duration of release. Kaplan et al (1974) reported significant increases in particulate phosphates, silicates and chlorophyll a immediately after a hydraulic dred ion in a small enclosed coastal embayment which also .ging operat received the effluent from the disposal area. There was no appreciable difference in levels of nitrates, nitrites and dissolved organic and inorganic phosphates before and After dredging. 244 Alth ough not strictly an impact on water quality the increased rate of sedimentation in the vicinity of dredging operations can have an adverse effect on the area. Here again most of the impacts de scribed in the literature refer to open-water disposal operations. Wilson (1950) cited from Bouma (1976) studied the effects of shell dredging along the Texas Gulf coast. He reported that "suspended silt and resulting sedimentation extended in significant concentrations approximately. 300 yards from the dredge" and that oysters placed in baskets were covered with silt within 300 yards of the dredge if they were at the same depth as,the adjacent bottom but were not covered if th ey were placed higher. than the surrounding bottom. Mackin (1961) made several theoretical observations on the sedimentation possible from cutterhead and clamshell dredged utilizing open-water disposal on adjacent oyster leases. . These hypotheses were based on average tuibidities in ppm (not mg/1,TSS) in the sediment plume, current velocities, open-wate r disposal immediately adjacent to the dredge and the distance to nearby oyster leases. The amounts of sedimentation theoretically expected ranged from 0.2 inches on a seven acre lease 1500 feet from a cutterhead dredge with average plume values of 500 ppm turbidity to 0.5 inches on a 1000 foot long area immediately adjacent to the disposal area with an average plume value of 200 ppm turbidity from a clamshell dredge. He stated that the maximum distance the spoil was transported from the discharge pipe of a hydraulic dredge was 1300 feet. Ingle (1952) in a study of the effects of dredging on fish and shell- fish reported that it appeared that all potentially deleterious particles had settled to the bottom within 300-400 yards of an active dredge with overboard disposal. Average sedimentation rates at 75 yards from a dredge were .228 inches/hr. just off the bottom and .108 inches/hr at mid-depth. 245 Hellier and Kornicker (1962) measured the sedimentation rate around an open-water spoil disposal site in Aransas Pass, Texas. Stations were established at 0.03, 0.5$ 1.0, 1.5 and 2.0 miles in a line perpendicular from the channel. The spoil was deposited between the first two stations. Background sedimentation rates were 2-3 mm for a nine month period. One week after dredging there were seven cm of sediment on the 0.03 mi. station and 22 cm on the 0.5 mi. station. Sedimentation at the 1.0, 1.5, and 2.0 mi. stations was negligible. Boone and Byrne (1975) in a study of a dredging project on Hampton Bar, Va. reported bottom deposition resulting from the dredging activity was primarily restricted to an area within a 200 yard radius of the dredge. Impacts on Estuarine Organisms Phytoplankton. The reported effects of dredging and dredge spoil disposal on phytoplankton and primary production are many and varied depending upon the situation at each site. These range from a significant reduction in carbon uptake by phytoplankters,(Sherk et al, 1976) to a substantial increase in primary production (Subba Rao, 1973) to no observable effect (Flemer, 1970) to a combined effect of reduced photosynthesis by increased light attenuation and the stimulation of photosynthesis by the introduction of nutrients (Odum and Wilson, 1962). For*specific levels of impact please refer to Table Crustaceans. The possible impacts of dredging on this group of organisms include interference with feeding, clogging of gills.@and heavy metals and pesticide uptake. The levels of TSS normally encountered in upland disposal type dredging operations, a few hundred mg/l maximum, will. probably cause some reduction in feeding efficiency and probably some interference with respiration of selected copepods (See Table 2). However, 246 the areal extent of the highest levels of TSS is very small, a radius of a few hundred meters maximum around the dredge. The impact, in all but the smallest of water bodies, should be minimal. Peddicord and McFarland (1978) reported uptake by decapod crustaceans of heavy metals and polychlorinated hydrocarbons on a limited basis. These accumulations occurred after days of exposure t6 fluid mud concentrations (grams to tens of grams/liter) of highly contaminated sediments. Neither the TSS concentration levels nor the duration of exposure can be expected during dredging with upland disposal operations. Sullivan and Hancock (1977) reviewed the general impacts of dredging on zooplankton. Mollusks. While the adults of this group of organisms are very susceptible to adverse impacts from dredging due to their sessile nature, it is also a group that has adapted to the most turbid portion of the water column. The pumping rate of adult bivalves can be adversely affected by levels of TSS generated by dredging, a few hundreds of mg/l (Table 3). However,they are also adapted to.survive long periods with both valves closed or at reduced @umping rates to accommodate naturally occurring periods of adverse conditions. The eggs of oysters are susceptible to a substantial reduction in their development at TSS concentrations of silt in the upper range of those expected from dredging operations (See Table 4). Oyster egg development is affected by lower concentrations of silt than are hard clam eggs. The larvae of oysters and clams, however, do not appear to be significantly affected until they are exposed to concentrations of silt in excess of normal dredging operation levels. Here again oyster larvae appear to be more susceptible than clam larvae (Table 4). 40 247 Fishes. With the exception of juvenile striped bass and silversides concentrations of TSS lethal to fishes are not even approached until they are exposed to levels one to two orders of magnitude above dredging levels for extended periods of time (Table 5). The sublethal effects listed in Table 6 are also not experienced by fishes until levels of TSS above normal dredging operations are reached with exposure times that do not appear realistic for animals as motile as fish. The significance of the changes in blood chemistry listed is not completely understood but are symptomatic of an organism undergoing oxygen. deprivation. The effects of increases TSS concentrations on the eggs and,larvae of fishes are listed in Table 7. The only effect on the eggs of four species by TSS levels at the extreme upper limit of those expected from a dredging operation was a one hour delay in hatching over controls. Lethal concentra- tions (LC 50) of TSS on the fish larvae studies were far in excess of anticipated levels from dredging. Several general observations are in order on the experiments done to ascertain the impact of suspended solids on aquatic organisms. Direct comparisons between the impacts natural sediments and those of processed materials, e.g. Kaolin, Fuller's earth, etc., cannot be routinely made because in some instances effects may have been observed at low levels with the processed materials but similar effects were not observed until much higher levels of natural sediments were reached,and vice versa.. The. degree!of contamination of natural sediments with heavy metals, hydrocarbons, pestIicides and other pollutants can also play a significant role in the observed impacts on aquatic organisms. Dissolved oxygen levels and temperature also affect the impacts of suspended solids. Organisms appeared to fair better at high dissolved 248 oxygen levels and low temperatures than they did at low dissolved oxygen levels and high temperatures (Peddicord et al, 1975). The habitat in which the organisms are normally found also influences the level at which the organism is impacted by suspended solids. Those living in naturally highly turbid areas are usually better adapted than those preferring relatively cle ar water. 249 Summary and Conclusions In general, it may be concluded from the results of this review that the effects of dredging with confined upland spoil disposal are limited. They include: a. Minor impacts on phytoplanktondue to reduced light penetration which is often offset by increased nutrient availability. b. Limited interference with zooplankton feeding immediately adjacent to the dredge due to increased TSS. c. Reduction in development of oyster eggs due to increased TSS. d. Possible slight increase in sedimentation adjacent to the dredge which might affect adjacent shellfish beds. e. Based on the nutrient and.pollutant.release data from open-water disposal operations, very limited increases of manganese, iron, ammonium nitrogen, orthophosphate and reactive silica can be' expected. Under very specific conditions the possibility also exists for the limited release of other heavy metals and pesticides during dredging operations. f. In some instances there is a reduction of D.O. of 1-2 mg/1 when dredging normal harbor sediments. These impacts are primarily restricted to the immediate vicinity of the dredge, a radius of a few hundred meters. Tidal and wind generated currents will usually provide sufficient mixing and dilution to return the water to near background levels within this distance. Table 1. The effects of various suspended so ids on phytoplankton LIFE SPECIES STAGES CONC. EXPOSURE MATERIAL EFFECT SOURCE Monochrysis lutheri NA 2,250 mg/l NS S102 median 80% reduction in Sherk, etal., 1976 size 17.,um carbon.uptake M. lutheri NA 250 mg/l NS S102 approx. 23% reduction in carbon uptake Chlorella sp. NA 1,000 mg/l NS Si02 median 90% reduction in size 6.2 Am carbon uptake Chlorella sp. NA 250 mg/l NS Si02 approx* 30% reduction in carbon uptake Nannochloris sp. NA 250 mg/l NS Si02 approx. 28% reduction in carbon uptake Nannochloris sp. NA 1,000 mg/l NS Si02 pz@rticles 90% reduction in <15 pm carbon uptake Table 2. The effects of various suspended solids concentrations on crustaceans LIFE SPECIES STAGE CONC. EXPOSURE MATERIAL EFFECT SOURCE Eury emora affinis adult 500 mg/l NS Si02( 15 ave. 49.5% reduction Sherk, et al., 1976 in algal uptake 500 mg/1 " Fuller's earth 42% reduction in algal uptake 500 mg/l " natural ave. 62.6% reduction sediment in algal uptake Acartia tonsa adult 100 mg/l NS Si02( 15 jim) ave. 66.6% reduction in algal uptake to 100 mg/l " Fuller's earth ave. 67.5% reduction in algal uptake 500 mg/l " nat. sediment 72.9% reduction in algal uptake Cranr,on nigromaculata adult 50,000 mg/l 200 hrs. Kaolin LC50 Peddicord et al., 1975 Homarus americanus adult 50,000 mg/l NS Kaolin no mortality Saila et al., 1968 1,600 ppm NS harbor sed. no martality cited from Stern and Strickle, 1978 Palaemon macrodactyl Ius adult 77,000 mg/l 200 hrs. Kaolin LC Peddicord et al., 1975 20 Cancer MaLister adult 3,500 mg/1 21 days contaminated LC Peddicord and sediment 10 McFarland, 1978 Crangon nigricauda 4-6 cm 21,500 mg/l 21 days 20% mortality Table 3. The effects of various suspended solids concentrations on mollusks LIFE SPECIES STAGE CONC. EXPOSURE MATERIAL EFFECT SOURCE 4.1000- C. virginica- adult extended sediment detrimental Wilson, 1950 32,000 mg/1 100-700 ppm NS mud no apparent problems Mackin, 1961 100-4,000 NS Silt 57-94% reduction in Loosanoff & Tommers, mg/l pumping 1948 Mytilus edulis 2.5 cm 100,000 mg/l 5 days kaolin 10% mortality Peddicord et al., 1975 10 cm 100,000 mg/l 11 days kaolin 10% mortality Peddicord et al., 1975 10 cm 96,000 mg/l 200 hrs. kaolin 50 Peddicord et al., .1975 Crepidula fornicata adult 200-600 mg/l NS NS pronounced reduction Johnson, 1971 infiltration rate Mytilus edulis 1@,0-2.5 2,300 mg/l 21 days contaminated LC 10 Peddicord and McFarland, sediment .1978 Ln Table 4. The effects of various suspended s lids concentrations on the eggs and larvae of mollusks LIFE SPECIES STAGE CONC. EXPOSURE MATERIAL EFFECT SOURCE 22% reduction in Crassostrea virginica egg 188 mg/1 NS silt number developing to Davi.v & Hidu, 1969 straight hinge larval stage 250 mg/l NS silt 27% 375 mg/l NS silt 34% <1000 mg/1 NS Fulleris no sign ificant re- earth duction in number developing to straight <2000 mg/1 NS Kaolin hinge larvae Mercenaria mercenaria egg 750 mg/l NS silt 8% reduction-in number Davis, 1960 developing to straight hinge larvae 1000 mg/l NS silt 21% Davis, 1960 1500 mg/l NS silt 35% 125 mg/l NS Kaolin 18% Davis, 1960 NS Fuller's 25% earth 4000_mg/l NS Si0q. <5 u -31% Davis & Hidu, 1969 C. virginica larvae >750 mg/l 12 days silt significant reduction in survival Davis & Hidu, 1969 11 If it 2000 mg/l 11 Fuller's 20% reduction in Davis & Hidu, 1969'W'" earth survival If 500 mg/l 'NS Si02 <5 u 78% reduction in survival Table 4. continued LIFE SPECIES STAGE CONC. EXPOSURE MATERIAL EFFECT SOURCE Mercenaria mercenaria larvae 1000@mg/l NS silt normal growth Davis, 1960 500 mg/1 12 days Kaolin 50% reduction in survival Ln Table 5. Lethal effects of various suspended solids concentration on fishes LIFE r SPECIES STAGE CONC. EXPOSURE MATERIAL EFFECT SOURCE Leiostomus xanthurus adult 13,090 mg/l 24 hrs. Fuller's LCio Sherk et al., 1975 earth 68,750 mg/l If Patuxent LC10 silt Morone americana, adult 9,970 mg/l Patuxent LC10 O'Conner et al., 1976 silt Is It 3,050 mg/l Fuller's LC10 Sherk, et al., 1975 earth Fundulus majalis 23,770 mg/l Fuller's LC 10 earth 97,200 mg/l Patuxent LC 10 silt F. heteroclitus 24,470 mg/l Fuller's LCIO earth Menidia menidia 580 mg/l Fuller's LCio earth Brevoortia tyrannus juvenile 1,540 mg/l Fuller's LCIO earth Anchoa mitchilli adult 2,310 mg/l Fuller's LCIO earth Morone saxatilis 5-6 cm 4,000 mg/l 21 days uncontaminated LC Peddicord and McFarland, 10 sediment 1978 Cn 400 mg/l 2 days contaminated LC50 sediment Table 6. The sublethal effects of various su pended solids concentrations on fishes. LIFE SPECIES STAGE CONC. EXPOSURE MATERIAL EFFECT SOURCE Morone americana adult 650 mg/l 5 days Fuller's earth increased micro- O'Connor et al. matocrit, hemoglobin 1977 concentration & Red Blood cell count over control M. americana if 2000 mg/1 6 days Natural significant increase sediment in RBC, hematocrit & hemoglobin 14 days control & experimental similar Trinectes maculatus adult 1240 mg/1 5 days Fuller's earth increased hematocrit & RBC count; reduction in liver glycogen content Fundulus majalis adult 960 mg/l 5 days Fuller's earth increased hematocrit F. heteroclitus adult 1600 mg/1 4 days if It it Leiostomus xanthurus adult 1270 mg/l 5 days Fuller's earth no significant difference in blood chemistry over control L. xanthurus 16,960 mg/1 7 days Natural sediment Opsanus tau adult 14,600 mg/l 3 days Natural sediment Morone saxatilis adult 1500 mg/1 14 days Fuller's earth increased hematocrit M. saxatilis 1500-6000 mg/l 6 days Natural mud no significant change in blood chemistry over control table 7. The effects of various suspended solids concentrations of fish eggs and larvae. LIFE SPECIES STAGE CONC. EXPOSURE MATERIAL EFFECT SOURCE Perca falvescens eggs 500 mg/l NS natural fine No.statistically Schubel & Wang, 1973 grained significant effect sediment on hatching success, although a several Morone americana hour delay inhato4- ing was frequently Morone saxatilis observed about 100 Mg/l Alosa pseudoharengus M. americana larvae 2679 mg/1 48 hr. NS LC 50 Morganet al., 1973 cited from Sternand Stickle, 1978 M. saxatilis larvae 3411 mg/1 LC it 50 M. americana. larvae 3730 mg/1 eggs 4000 mg/1 NS NS Delayed hatching one day 258 BIBLIOGRAPHY Allen, K. 0. and J. W. Hardy. 1980. Impacts of navigational dredging on fish and wildlife: a literature review. U. S. Fish and Wildlife Service, Biological Services Program. FWS/OBS-80/07. 81 pp. Barnard, W. D. 1978. Prediction and control of dredged material dispersion around dredging and open-water pipeline disposal operations. Technical Report DS-79-13, U.S. Army Engineer Waterways Experiment Station, CE, Vicksburg, Miss. 102 pp. Boon, J. D. and R. J. Byrne. 1975. Hampton Bar dredging project, Newport News Shipbuilding and Dry Dock Co. borrow site, monitor of turbidity and sedimentation. Final Report, Va. Inst. Mar. Sci., Gloucester Point, Va-. 46 pp. Boon, J. D. and G. R. Thomas. 1975. Report on environmental effects of the second Hampton Roads Bridge-Tunnel construction: sediment distributions and bottom characteristics. Contract Report, Va. Inst. of Mar. Sci. Gloucester Point, Va. 51 pp. Bouma, A. H. 1976. Shell dredging and its influence on Gulf coast environments. Gulf Publishing Company, Houston, Texas. 454 pp. Brown, C. L. and R. Clark. 1968. Observations on dredging and dissolved oxygen in a tidal waterway. Water Resources Res. 4(6):1381-1384. Burks, S. A. and R. M. Engler. 1978. Water quality impacts of dredged material disposal (laboratory investigations). Technical Report DS- 78-4, U.S. Army Engineer Waterways Experiment Station, CE, Vicksburg, Miss. 35 pp. Davis, H. C. 1960. Effects of turbidity-producing materials in sea water on eggs and larvae of the clam (Venus (Mercenaria) meftendria). Biol. Bull. 118(l):48-54. Davis, H. C. and H. Hidu. 1969. Effects of turbidity-producing substances in sea water on eggs and larvae of three genera of bivalves mollusks. Veliger 11(4):316-323. Chesapeake Biological Laboratory. 1970. Gross physical and biological effects of overboard spoil disposal in upper Chesapeake Bay. Nat. Res. Inst. Spec. Rep. No. 3, Univ. of Maryland, Solomons. 66 pp. Flemer, D. A. 1970. "Phytoplankton", gross physical and biological effects of overboard spoil disposal in upper Chesapeake Bay, Special Report No. 3, Natural Resources Institute, Univ. Maryland, College Park, Md. Hellier, T. R. and L. S. Kornicker. 1962. Sedimentation from a hydraulic dredge in a bay. Publ. Inst. Mar. Sci., Univ. Texas 8:212-215. Hirsch, N. D., L. H. Disalvo and R. K. Peddicord. 1978. Effects of dredging and disposal on aquatic organisms. Technical Report DS-78-5, U.S. Army Engineer Waterways Experiment Station, CE, Vicksburg, Miss. 41 pp. 259 Ingle, R. M. 1952. Studies on the effect of dredging operations upon fish and shellfish, Tech. Ser. No. 5. State of Florida, Board of Conservation, Tallahassee, Fla. 26 pp. 40 Johnson, J. K. 1971. Effect of turbidity on the rate of filtration.and growth of the slipper limpet, Crepidula fornidata Lamarck, 1799. The Veliger 14(3):315-320. Kaplan, E. H., J. R. Welker and M. G. Kraus. 1974. Some effects of dredging on populations of macrobenthic organisms. Fishery Bulletin 72 (2) :455-480. Loosanoff, V. 1961. Effects of turbidity on some larval and adult bivalves. .Proc. Gulf Carrib. Fish. Inst. 14:80-95.. Loosanoff, V. L. and F. D. Tommers. 1948. Effect of suspended silt and other substances on rate of feeding of oysters. Science 107(2768): 69-70. Mackin, J. G. 1961. Canal dredging and silting in Louisiana bays. Publ. Inst. Mar. Sci., Univ. Texas. 7:262-314. May, E. B. 1973. Environmental effects of hydraulic dredging in estuaries. Alabama Marine Resources Bulletin 9:1-85. Morgan, R. P., V. J. Rasin and L. A. Noe. 1973. Effects of suspended sediments on the development of eggs and larvae of striped bass and white perch. Ref. No. 73-110. Univ. Md. Nat. Res. Inst., College Park, Md. Morton, J. W. 1977. Ecological effects of dredging and dredge spoil disposal: a literature review. U. S. Fish and Wildlife Service Technical Paper No. 94. 33 pp. O'Connor, J. M.P D. A. Neumann , and J. A. Sherk. 1976. Lethal effects of suspended sediment on estuarine fish. Technical Paper No. 76-20, U.S. Army Engineer Coastal Engineering Research Center, Fort Belvoir, Va. 38 pp. Odum, H. T. and R. F. Wilson. 1962. Further studies on reaeration and metabolism of Texas bays, 1958-1960. Publ. Inst-Mar. Sci., Univ. Texas. 8:23-55. Peddicord, R. K., V. A. McFarland, D. P. Belfiori, and T. E. Byrd. 1975. Effects of suspended solids on San Francisco Bay organisms. U. S. Army Engineer District, San Francisco, Dredge Disposal Study. Appendix G- Physical Impact. 158 pp. Peddicord, R. K. and V. A. McFarland. 1978. Effects of suspended dredged material on aquatic animals. Technical Report D-78-29, U.S. Army Engineer Waterways Experiment Station, CE, Vicksburg, Miss. 102 pp. 260 Saila, S. B. 1980. Estuarine fishery resources and physical estuarine modifications: some suggestions for impact assessment. In: P. Hamilton and K. B. MacDonald (eds.), Estuarine and Wetland Processes. Plenum Publishing Corp., New York, N.Y. Saila, S. B., T. T. Pol gar and B. A. Rogers. 1968. Results of studies related todredged sediment dumping on Rhode Island Sound. Proc. Ann. Northeastern Reg. Anti-pollution Conf. 22-24 July 1968. pp. 71-80. Cited from: Saila, S. B., S. D. Pratt, and T. T. ' Polgar. 1972. Dredge spoil disposal in Rhode Island Sound. Univ. Rhode Island,- Mar. Tech. Rep. 2. 48 pp. Schubel, J. R. and J. C. S. Wang. 1973. The effects of suspended sediment on the hatching success of Perca flavescens (yellow perch), Morone americana (white perch), Mo@_rone saxatilis (striped bass), and Alosa pseudoharengus (alewife) eggs. Special Report No. 30. Chesapeake Bay Institute, Johns Hopkins Univ. Baltimore, Md. Sherk, J. A., J. M. O'Connon and D. A. Neumann. 1975. Effects of suspended and deposited sediments on estuarine environments. In: L. E. Cronin (ed.) Estuarine Research Vol. II. ERF. Academic Press, Inc., N.Y. 587 pp. Sherk, J. A., J. M. O'Connor and D. A. Newmann. 1976. Effects of suspended solids on selected estuarine plankton, Misc. Report No. 76-1. U. S. Army Coastal Engineering Research Center, CE, Fort Belvoir, Va. Stern, E. M..and W. B. Stickle. 1978. Effects of turbidity and suspended material in aquatic environments: literature review. Technical Report D-78-21, U.S. Army Engineer Waterways Experiment Station, CE, Vicksburg, Miss. 117 pp. Subba Rao, D. U. 1973. Effects of environmental perturbations on short- term phytoplankton production off Lawson's Bay, a tropical coastal embayment. Hydrobiologia 43:77-91. Sullivan, B. K. and D. R. Hancock. 1977. Zooplankton and dredging: research perspectives from a critical review. Water Resources Bulletin 13(3): 461-468. U. S. Army Engineer District, San Francisco. 1975. Dredge disposal study San Francisco Bay and estuary Appendix G Physical impact study. 158 pp. Effects of suspended solids on San Francisco Bay orgailisms. R. K. Peddicord, V. A. McFarland, D. P. Belfiori, and T. E. Byrd. Univ. of Calif. Bodega Marine Lab. Bodega Bay, Calif. 94923. U. S. Army Engineer District, San Francisco, CE, 1975. Dredge Disposal Study, San Francisco Bay and Estuary. Appendix M-Dredging Technology. U. S. Army Engineer District, San Francisco, CE, 1976. Dredge Disposal Study, San Francisco Bay and Estuary, Appendix C-Water Column. 98 pp. Williamson, K. J. and P. 0. Nelson. 1977. Environment and Quality. In: Dredging in Estuaries, Technical Manual. W. L. Schroeder, Principal Investigator Oregon State University, Corvallis, Oregon 97331 313 pp. 261 Wilson, W. B. 1950. The effects of sedimentation due to dredging operations on oysters in Copano Bay, Texas. M. S. Thesis, Agricultural and Mechanical College of Texas. 128 pp. Wright, T. D. 1978. Aquatic dredged material disposal impacts. Technical Report DS-78-1, U.S. Army Engineer Waterways Experiment Station, CE, Vicksburg, Miss. 57 pp. 262 Summary and Conclusions The aim of this report is to address the effects of dredging impacts on the Hampton Roads estuarine system. Its scope is limited by certain qualifications which were established at the beginning of the study. These qualifications must be considered before application of the conclusions and recommendations of this report can be deemed valid or appropriate for the dredging operation in question. The results of this report apply only to channel maintenance dredging where accumulated silt and clay are excavated from the bottom of an existing well-defined channel. Both hydraulic cutterhead and clamshell bucket methods of dredging are considered. The application of the results is primarily restricted to the principal study area which is Hampton Roads, the Elizabeth River and the Lower James River. Limited application of certain aspects of this study may be made to other areas by interpretation and extrapolation where very similar conditions exist. Dredging operations utilizing a confined upland disposal area are the only types considered. The dredge cutterhead and clamshell bucket are the only point sources of suspended solids considered in this report. Any impacts associated with disposal operations, open-water or otherwise, cannot be interpreted using the conclusions of this report. The study area is heavily utilized by marine resources despite its high degree of urbanization, industrialization and commercial shipping use. The Hampton Roads area supports large populations of hard clams. The Lower James River supports vitally important extensive seed oyster beds. The entire area is heavily utilized by a variety of finfish for spawning, nursery areas and/or feeding grounds. 263 The results of the field investigations and model predictions of the levels and distribution of suspended material and sedimentation indicate that: a. Both hydraulic and clamshell dredges generated suspended solids levels in excess of 200 mg/l. b. Dispersion and settling reduced the suspended solids generated by the dredges to background levels within approximately 300 meters down current to the dredge. c. Sedimentation rates predicted by the model decreased with increasing distance from the dredge. They ranged up to several millimeters 125 m laterally from the dredge, at right angles to the current flow and at the same depth as the dredging. In light of the impact threshold for marine resources utilizing the area and the suspended solids and sedimentation levels for dredging given in the literature and those observed and predicted by the model in this study, the following observations on the effects of dredging on these organisms and water quality are offered: a. Minor impact on phytoplankton photosynthesis due to reduced light penetration whichis often offset by increased nutrient availability. b. Limited interference with zoo*plankton feeding immediately adjacent to the dredge due to increased suspended solids. C. Reduction in the development of oyster eggs into larvae due to increased suspended solids in excess of 200 mg/l. d. Pronounced reduction in the pumping rate of oysters when levels exceed 100 mg/l. e. Increase in sediment accumulation in areas adjacent to the dredged area. This sedimentation may be significant enough within a few hundred meters to have an adverse effect on oysters, particularly spatfall and spat survival. 264 f. Lethal impacts on fishes should be minimal except for juvenile striped bass and atlantic silverside which are susceptible to levels of suspended solids on the order of 500 mg/l. White perch appear to undergo respiratory stress at approximately the same level. g. The eggs of several species of fish can experience a slight delay in hatching (a few hours) during exposure to suspended solids levels in excess of 100 mg/l. h. Generally, the releases of nutrients, heavy metals and pesticides should be small in quantity and of short duration. i. In some instances, there will be possibility of a reduction in Dissolved Oxygen by 1-2 mg/l near the dredge. This depends on numerous factors including the sediments being dredged, water temperature, and the dispersion capacity of the water body. Based on the above information, the potential exists for dredging operations in close proximity to productive oyster beds and certain fish spawning areas at certain times of the year to have an appreciable impact on these resources. Other resources will be impacted but the extent and duration should be minimal. In developing a management plan for dredging for Hampton Roads and the lower James River, it might be advisable to designate and classify areas of particular concern. The designation and classification of these important resource areas with respect to their potential for being affected by dredging at different times of the year could prove to be an effective tool for managing dredging in the Hampton Roads and lower James River area. A suggested scheme for designated areas of particular concern would include the following classifications which could be applied during the appropriate times of year: 265 Restricted - The potential exists for serious adverse impacts on adjacent resources. Dredging and disposal operations should be prohibited, except, possibly, for emergency situations during the most vulnerable times of the year to protect the resources. Conditional - Potential exists for adverse impacts on adjacent resources during certain times of the year. But due to the level of anticipated dredging and/or disposal impact, the proximity of the resources, or the marginal value of the areas to the resources, there are no absolutely critical times of the year when dredging should be prohibited. However, there may be times of the year when dredging and disposal operations should be avoided,,when possible,to minimize unnecessary adverse impacts. Open - Areas where the resources present are not especially susceptible to the adverse effects of dredging and/or disposal operations and time- of-year dredging restrictions are generally not warranted. This, however, does not preclude restrictions for exceptional situations which must be evaluated on a case-by-case basis. The application of this classification system for designated areas to the Hampton Roads-lower James River area included in the present study would involve the following: 1. The designation of the area between Deep Water Shoals and a line from Newport News Point to Pig Point in the lower James River as a restricted area for dredging during the oyster spawning and setting season (July, August and September). Dredging.within 500 meters of any other productive oyster bottom in the Hampton Roads study area during these months should also receive a restricted classification. 2. A conditional classification for the Southern Branch of the Elizabeth77 and its tributaries upstream of the 1-64 bridge during 266 the principal anadromous and resident fish spawning season (mid- March through June). This area is also heavily utilized as a nursery for postlarvae and juveniles of numerous fishes. 3. A conditional classification for dredging in the Southern Branch of the Elizabeth River during the warm weather months (July through September) might also be considered to help minimize the potential for creating dissolved oxygen depletion by adding the effects of dredging to already oxygen stressed conditions. However, this would be contingent upon the development of a sufficient body of data to indicate whether dredging contributes significantly to the reduction of dissolved oxygen levels. 40. 40 14P 3 6668 00004 8753 W