[From the U.S. Government Printing Office, www.gpo.gov]






                                                                            95.7.3   1


                 ASSESSMENT OF THE
                    EFFECTIVENESS OF
                              PERMANENT
            STORMWATER CONTROL
                                 MEASURES



                                         A Final Report to

            The New Hampshire Office of State Planning, New Hampshire Coastal Program


                                           Submitted by


                  Dr Stephen H. Jones and Dr. Richard Langan

                                   Jackson Estuarine Laboratory
                                   University of New Hampshire

                                         October, 1996         PrOPGZtY 09 CSC W%brary

           Ibis Report was funded in part by a grant from the Office of State Planning, New Hampshire
           Coastal Program, as authorized by the National Oceanic and Atmospheric Administration (NOAA),
           Grant Award Number NA570ZO320.



                                       U - 8 - DEPARTMENT OF COMMERCE NOAA
        TD                             COASTAL SERVICES CENTER
        657.5
                                       2234 SOUTH HOBSON AVENUE
        .J66
        1996                           CHARLESTON,, SC 29405-2413
        c.2
                                                                               Nit Coasfal Program











                                                 EXECUTIVE SUMMARY

                      The effectiveness of designed stormwater control systems for treating contaminants in
              runoff waters in coastal New Hampshire was studied. The objectives were to assess effectiveness
              and to determine which systems are most effective. A strong emphasis was placed on assessing
              systems during cold months because of the frequency of major stormtrunoff events that probably
              contributes significant loading of contaminants to surface waters. Measured water quality
              parameters were generally present in relatively low concentrations in both influent and effluent
              waters. Bacterial contaminants were a notable exception, with relatively high concentrations
              observed throughout the study in some systems. The infiltration chamber was apparently
              ineffective at treating any contaminant. The wet pond systems were relatively effective in treating
              many of the contaminants in both summer and winter, while the vegetated swales were
              inconsistently effective, especially during summer. The swales were not effective in treating
              nutrients and other dissolved contaminants during summertime when live plants are supposed to
              remove contaminants. Bacterial contaminants showed a definite trend of increasing concentrations
              with the onset of warm weather both in influent and effluent waters. This suggests that bacterial
              indicators are probably growing in the moist, nutrient-rich systems during dry periods between
              storms and are discharged with new storm events. Overall, the systems were not exposed to high
              levels of contaminants, and thus were discharging low levels of contaminants except for bacteria
              during summertime. The results should prove to be a useful basis for rule changes needed for
              achieving compliance with stormwater control standards. In addition, it will serve as a first step
              toward determining the public health significance of treated and untreated runoff from storm
              events.


                                                      INTRODUCTION

                      Runoff from impervious surfaces in urban areas contains significant amounts of hazardous
              contaminants, including microbial pathogens/indicators, heavy metals, and toxic organic
              compounds like oils and hydrocarbons. Both the Casco Bay and Massachusetts Bays National
              Estuaries Programs and associated research highlight stormwater control as a major issue relative
              to surface water contamination with toxic compounds. In coastal New Hampshire, all shellfish
              beds (Hampton and Little harbors; Great and Little bays and tributaries) are subject to bacterial
              contamination following major storm events to the extent that all beds are closed. Based on
              numerous recent studies, most of the contamination appears to be coming from urbanized areas. A
              major effort by the state and the region is currently underway to reduce bacterial contamination and
              reopen more shellfish beds. The threat of these contaminants entering surface waters has been
              addressed by NHDES which requires the use of a variety of permanent stormwater control
              measures designed to capture, treat, or reduce the contaminant content of the runoff from large
              impervious areas (parldrig lots; roofs).
                      In 1983, the US EPA reported on its National Urban Runoff Program (NURP), in which
              field data from 81 sites in 22 different cities were gathered over 1981 and 1982. Although a
              variety of chemical and microbiological constituents were measured in the runoff water samples,
              the following constituents were determined to be "...the standard pollutants characterizing urban
              runofF': total suspended solids, biochemical oxygen demand, chemical oxygen demand, total
              phosphorus, soluble phosphorus, total nitrogen, nitrate, nitrite, total copper, total lead and total
              zinc. One conclusion of the study was that dry systems consistently exhibited poor removal
              efficiencies for nitrate, nitrite and soluble phosphorus. This has lead to the design of many
              stormwater control facilities to have resident or permanent pools (wet systems).
                      There is an increasing body of data that indicates that wet stormwater control systems,
              catch basins and stormwater pipes may be enhancing microorganism and organic contamination
              (Ellis and Yu, 1995; Butler et al., 1995). In this study, field studies have been conducted to better









                 determine the extent of contamination from stormwater control systems, and to assess the
                 effectiveness of both new and old systems in coastal NH. The approach will emphasized
                 determining the fate of microbial and non-biological contaminants under different environmental
                 conditions and seasons.

                                                             METHODS

                         Ten sites at eight locations in the Great Bay watershed (Table 1) were sampled and
                 analyzed during five rainfall events (Tables 2 and 3) between January and September, 1996. The
                 land use was commercial at all locations and consisted of five shopping center parking lots, two
                 work site lots, and a lot at a marina. The descriptions of the storinwater control systems at each
                 sampling location are presented in Table 1.
                         Sampling occurred during the initial flush of the storm, essentially during the first 0.5" of
                 rainfall. Most stomis approached the area from the west or southwest, and sampling sequences
                 occurred along two north to south transects-(see Figure 1). One sampling pair would sample
                 SWI, SW2, DS and SP, in that order. The other sampling pair sampled PC, BJ, CC, PWI&2,
                 and NM, usually in that order. Measurements of temperature, conductivity, water flow velocity
                 and observations of weather and system conditions were recorded at sampling times. At some
                 sites, influent or effluent pipes and surrounding areas were modified to allow for measurement of
                 flow velocity. Detailed field notes recorded sampling site and system conditions, and any
                 problems encountered with sampling at different times of year. Separate containers were used for
                 collection of water samples for microbial, metals, oil and grease, BOD, COD and nutrient
                 analyses. Thus, six separate bottles were required for sampling from each of the two locations at
                 each site. Bottles for microbial analyses were cleaned and autoclave-sterilized. Nutrient bottles
                 were acid-washed and rinsed with deionized water. Metal sampling, COD and oil and grease
                 bottles were cleaned and contained acids for preservation of samples. BOD bottles were also
                 cleaned and rinsed prior to sampling. All samples were immediately refrigerated and transported
                 back to JEL within 3 hours of collection. Samples for analysis by NHDES were transported on ice
                 on the day of sampling or the next day.
                         At JEL, total phosphates were measured using for a persulfate digestion method. Total
                 nitrogen was analyzed using a Shimadzu. ion specific chromatography with an ANTEK Nitrogen
                 detector. Microbial analysis of JEL samples involved standard membrane filtration methods using
                 mTEC agar for detection of fecal colifomis and Escherichia coli., with incubation of plates at
                 44.5'C for 24 h. Urea substrate was used to differentiate E. coli from fecal coliforms. At
                 NHDES, samples were analyzed for aluminum, cadmium, copper, zinc, chloride, turbidity, BOD,
                 COD and oil/grease according to standardized methods.
                         Means or geometric means were established for all parameters and graphed to determine
                 differences between systems and with season. The variety of storm and seasonal conditions under
                 which the samples were collected at the variety of different types of stormwater control systems for
                 only five events are reasons why rigorous statistical analysis was not conducted on the data.
                 Contaminant concentrations were compared to published criteria for the protection of aquatic life,
                 EPA 6217 guidelines, and classification standards for freshwater and shellfish-growing waters.
                 The effectiveness of individual and types of systems were assessed by comparing contaminant
                 removal efficiencies to published expected values.

                                                RESULTS AND DISCUSSION

                         Sampling during the five storm events was affected by a variety of factors. As presented in
                 Table 2, some of the systems were not functioning as designed.

                         -At SP, water from the parking lot adjacent to the treatment swale was transported by sheet


                                                                   2









              flow into the swale over a small vegetated berm during all events, whereas the system was
              designed to treat water collected from the parking lot via drainage through manhole grates.
                      -At SW2 and PW2, the level spreader were causing serious erosion of the surrounding
              receiving area because water flowed out of the spreaders in high-flow streams, and not by sheet
              flow across the area of the spreader.
                      -At CC, the v-notch weir was largely disfunctional because water flowed mainly through a
              crack below the notch when water height behind the weir was relatively shallow, making
              measurement of water flow difficult.
                      -At PC, snow plowed from the parking lot was piled and compacted over the treatment
              swale area. In addition, the water from the relatively small parking lot flowed through breaks in
              the curbing around the lot into a short swale and out through a small level spreader. Overall, the
              water quality in the water from the building roof and back shipping area was cleaner than the water
              from the parking lot discharging from the level spreader.
                      At PW1, the diked pond seemed to be functioning as designed, except that a medium-sized
              drain from adjacent U.S. Route 1 emptied into the pond -15' from the system, effluent pipe. Ibis
              generally caused the discharged effluent waters to be more contaminated than the water further into
              the diked area.
                      At NM, the system had plowed snow interfering with sampling in winter and the water
              seemed to disappear a short distance into the swale from the influent pipe during summer.

              Measurements of flow were taken when possible under the conditions at the sites. Many of the
              systems, especially the ponds, had standing water with little or no apparent flow of water.At sites
              where flow velocity was measured, it appeared that flow was similar during the January and July
              storms. However, the September storm never developed into the storm it was predicted to
              become, and flow was never intense. Temperature of sample water was never variable between
              sites on a given day.
                      Table 3 presents meteorological conditions during and prior to the sampled storm events.
              Hourly rainfall dam was available for the first few sampling events at the time of writing this
              report, and those data were never received in time for inclusion. The first two events were
              relatively average rainfall events, but were marked by significant snow melt. This was especially
              true for the first event on January 19, 1996, when snow depth recorded in Durham decreased from
              24" to 11 " in two days". The April and July storms were significant events, and came during
              periods following previous storm events. As previously mentioned, the September storm event
              never materialized into the major storm it was predicted to be, being part of a hurricane system. In
              addition, the September event was only the second rainfall event in the previous 30 days, when the
              hot weather and lack of rainfall caused the groundwater level to drop and the soils conducive to
              holding rainfall. These conditions are some of the reasons for the lack of water flow and
              significant runoff during this event.
                      Ile following sections of the Results are organized according to the 1111itial objectives that
              were the basis for conducting this prpject.

              Effectiveness of existing stormwater control Vstems at removing NPS pollutants

                      The c6ntaminant concentrations at the ten sampling sites for the five storm events are
              presented in Tables 4 and 5. Average concentrations for the five storms are calculated for the non-
              biological water quality 'variables and geometric means for the bacterial contaminants. Many of the
              non-biological variables were non-detectable for some sites and dates. Averages. were calculated
              assuming those values were equal to the detection limit. Ile sites with the highest bacterial
              contaminant levels were SW1 -I, CC-E and BJ-E during winter storms, while many sites had
              elevated bacterial levels during summer storms.
                      Additional information in Table 5 include ratios of the influent to effluent geometric means


                                                               3









                 for each sampling site. Sites with ratios >1 showed evidence of treatment occurring for that
                 contaminant in the control system. In addition, the ratios of FC to E. coli were calculated to
                 determine what portion of the total FC counts were E. coli.. Ratios much greater than I suggest
                 that those samples had elevated fractions of FC that were probably not of fecal origin, and may
                 reflect regrowth of FC-positive bacteria within the systems. Seven sites had FC:Ec ratios >2,
                 including influent water into the pond systems SWI-I, SW2-I, PWl-I and PW2-I, and effluent
                 water at the pond SWI-E and the swales DS-E,and NM-E. Notably, the sites (SWI-1, CC-E, BJ-
                 E) with the highest bacterial levels during winter when regrowth is less likely to occur, had FC:Ec
                 ratios close to or equal to one, indicating that the bacteria were more likely indicative of a fecal
                 contamination source.
                          One way of assessing the effectiveness of the test systems is to determine if the effluent
                 water meets water quality criteria. The State of New Hampshire has recently adopted water quality
                 criteria for toxic substances for the protection of both aquatic life in fresh and marine waters and of
                 human health for water and fish ingestion (NHDES, 1996). All of the system effluent waters
                 discharged into natural wetland habitats, so the criteria for protection of aquatic life in fresh water
                 were used to compare to measured toxic substance concentrations at the study sites (Table 6). For
                 the five contaminants, concentration ranges are listed along with the sites with concentrations that
                 fall into ranges above the fresh acute criteria and below the fresh chronic criteria. The acute criteria
                 for aluminum, copper and zinc were commonly exceeded at many sites, especially during the two
                 winter storms.For cadmium and chloride, even the chronic criteria were not exceeded during
                 summer storms, and sites exceeding acute criteria were uncommon during winter storms. The
                 sites at PW, 9i and 9e, were commonly below the chronic criteria for the different toxic
                 substances.
                          Stoxmwater is known to contain the target contaminants at elevated levels, and stormwater
                 control systems are designed to treat these contaminants to a limited extent. Thus, the above
                 described instances of exceeding of water quality criteria for protection of aquatic life are not
                 surprising. Another approach for assessing the effectiveness of these systems is to determine if the
                 effluent from the control systems meets stormwater control standards outlined by the U.S. EPA in
                 6217 guidelines (USEPA, 1993). In these guidelines, estimated mean runoff concentrations of
                 water quality param eters for different land uses are presented, based on the National Urban Runoff
                 Program (NURP) studies. The criteria for commercial land use are presented in Table 6 for copper
                 and zinc. These concentrations are much higher than the acute criteria used previously. For
                 copper, only sites 9i and 6i during the January storms exceeded the NURP concentrations, which
                 are estimated mean concentrations. The copper concentration at site 9i was 109 mg/l and the
                 concentration at 6i was 59 mg/l, both relatively close to the NURP concentration of 50 mg/l. For
                 zinc, the NURP concentration of 418 was exceeded only at site 7i on 9/8/96, where the zinc
                 concentration was 686, again quite close to the NURP concentration. Thus, the stormwater
                 systems are discharging contaminants at levels that are typically on the low end of average runoff
                 from commercial sites. '
                          Table 7 presents results for other non-toxic/non-biological contaminants. NURP
                 concentrations were available for total phosphorus, total nitrogen, BOD and COD. A turbidity
                 concentration of 10 NTU and an oil/grease concentration of 10 mg/l were chosen for comparison.
                 The turbidity concentration of 10 NTU would be the Emit for Class B waters if there was no
                 measurable turbidity under naturally occurring conditions for these systems. This conservative
                 criterion was only exceeded at a few sites, with no more than 5 sites exceeding the criterion for any
                 given storm. Some of the@samples probably had elevated turbidity as a result of having to sample
                 extremely shallow 'water on some dates. This was especially true on 9/8/9.6, when 5 sites were
                 >10 NTU, and little water was flowing in the systems. The extremely low concentration of 10
                 mg/l oil/grease was only exceeded four times, and the highest concentration was only 20 mg/l.
                 Thus, these systems had little in the way of oil and grease in influent and effluent water.
                          NURP concentrations were exceeded on only a few occasions for the other parameters.


                                                                     4









                The NURP concentration of 2.29 mg total PA was never exceeded, while the concentration of 1.5
                mg total N/l was exceeded twice on each January storm and at four sites on 9/8/96. The highest
                total N concentration was only 3.18 mg/l, barely twice the NURP mean estimate. Ile results for
                9/8/96 again probably reflect the presence of nitrogen in stagnant water left from a previous storm
                (Butler et al., 1995). The relatively high levels at site le during winter may be related to the
                elevated fecal bacterial concentrations observed at this site during winter storms. BOD and COD
                NURP concentrations were also exceeded only on rare occasions. The concentration of 14 mg
                BOD/I was exceeded only once during the first four storms, then at four sites on 9/8/96, and the
                highest concentration was only 16.7 mg/l. The concentration of 84 mg CODA was exceeded four
                times during January storms and twice thereafter, with the highest concentration being 218 mg/l.
                Thus, none of these other contaminants were present at high concentrations, and generally the
                systems had low levels of contaminants in both the influent and effluent waters.
                        Bacterial contaminant concentrations were compared to criteria used for classifying
                shellfish-growing waters (fecal coliforms) and for freshwater recreational areas (E. coli).
                Surprisingly, the sites that exceeded FC also typically exceeded E. coli criteria. During the second,
                third and fourth storms, the same exact sites that exceeded the FC criteria also exceeded the E. coli
                criteria. In the fifth storm, one extra site exceeded the FC concentration of 88 FC/100 ml, while
                five more sites exceeded the FC concentration in the first storm. The E. coli concentration of
                126/100 ml was exceeded less often during winter and the April storms (4-5 sites/storm) and more
                frequently during surnmer storms (13-14 sites/storm). Sites with low E. coli (<47/100 MI) were
                more frequent in winter (10-13 sites/storm) than in summer (1-3 sites/storm), thus supporting the
                observation of increasing bacterial concentrations during warmer months. No NURP
                concentrations were available for comparison to typical stormwater concentrations, but the high
                concentrations of bacteria for each storm"were relatively high,, ranging from 520 to 528,000
                FC/100 ml and 500 to 48,000 E. colillOO ml. Unlike the other contaminants, the elevated levels of
                bacterial contaminants are frequent enough to cause concern.

                CQm_parisons of the effectiveness of different Ustern Mes
                        Another major objective of this study was to deterriiine which type of system, if any, is
                effective for removing NPS pollutants from runoff water. In particular, the effectiveness of new,
                "state-of-the-art" systems compared to older systems was of interest. The approach taken to
                evaluate the effectiveness of the different systems was to look at contaminant removal efficiencies.
                The removal efficiencies (% of I removed in E) for each study system are presented in Table 9 for
                COD, turbidity, zinc, total N and total P. The study systems were grouped into wet ponds,
                vegetated swales and an infiltration chamber. EPA estimates for removal efficiencies for these
                different control systems- and contaminants are published (USEPA, 1993), and -are included in
                Table 9, along with the average efficiencies for the different types of systems for each storm.
                Table 10 presents the same information for aluminum, cadmium, copper, fecal coliforms, E. coli,
                oil/grease, chloride and BOD, only without the EPA estimated removal efficiencies. In general, the
                infiltration chamber was ineffective for treating all contaminants, and performed well below the
                estimated removal values. Wet ponds are relatively effective for treating the contaminants listed in
                Table 9, but are ineffective'for contaminants in Table 10, except for copper andoil/grease.
                Vegetated swales appeared to be relatively effective in removing copper and oil/grease, but were
                ineffective for all of the'other contaminants. The high negative values for removal of turbidity and
                total P were greatly influenced by site PC, where the effluent sample was most often collected from
                the level spreader that also collected large amounts of untreated parking lot runoff. Again, the
                variability of conditions under which'samples were collected probably has a large influence on
                these results. However, the overall ineffectiveness of the vegetated systems, the swales and
                ponds, illustrates the known limitations of- these systems during much of the year in cold climates
                (USEPA, 1993).
                        The largest. negative removal numbers were observed for chloride (Table 10), especially in


                                                                      5









                the vegetated systems. Of course, the immense amount of road salt applied to the parking lots has
                a large effect on this parameter. The other highest negative removal values were for bacterial
                contarninants (Table 10), especially in the infiltration chamber. The data in Table 5 and Figures 2
                and 3 show the worst systems are BJ and CC, with only one high number at PC giving a high
                negative removal number in Table 10. Both at BJ and CC, bacterial levels were always high in the
                E locations and relatively low in the I locations. This implies that there may be either sources of
                bacteria in the systems, or that the system is conducive to regrowth and sustained survival of the
                target bacteria. It is conceivable at BJ that temperatures in the below-ground system could be
                warm enough to nurture fecal-bome bacteria and sustain populations in moist, nutrient-enriched
                conditions between storms, even during winter. Thus, the systems studied appear to be at best
                inconsistently effective in removing contaminants from runoff, and at worst may be increasing
                concentrations of some contaminants (bacteria, nitrogen).

                Seasonal influences on control system effectiveness

                       The typical stormwater control system with vegetation is designed so that the live plants
                will interact with the runoff to remove contaminants. Ile plants reduce flow velocity and are
                capable of active uptake of dissolved contaminants, thus v
                                                                        ying them up in a form that could be
                removed with maintenance routines. This study purposefully included three major storm/runoff
                events during the colder months, because the frequency of major runoff events is high during
                colder months and stormwater-driven loading to surface waters probably is significantly dominated
                by colder month events. Two summer storm events were also included to give a balanced
                assessment of the systems at all times of year. The data in Tables 9 and 10 have presented to
                differentiate summer from winter removal efficiencies. The wet ponds were relatively effective for
                removing COD, turbidity, copper, oil/grease and zinc during winter along with total P and BOD
                during summer. Total N was effectively removed during summer but there was evidence of
                nitrogen generation or a source during winter in these systems, especially at SWL
                       Vegetated swales were inconsistently effective with season. During winter, apparently
                effective removal of aluminum, copper, E. coli, and oil/grease were observed in these systems, but
                all contaminants showed negative removal rates during summer. The design of vegetated systems
                is based on the fact that live plants will help to remove dissolved contaminants. Both vegetated
                swales and wet ponds have better removal efficiencies during summer than in winter, but they do
                poorly with total P during summer storms.
                       Storm control systems have been shown to be active as physical, chemical and biological
                reactors during dry periods between storm events (Butler et al., 1995). Biological processes that
                would affect the solubility of metals, ammonium generation, and bacterial regrowth would be
                especially important during warm months, as the colder months are too cold to support biological
                activity in New Hampshire. Ellis and Yu (1995) reported extended bacterial survival and regrowth
                in the nutrient-rich sediments of combined sewers, similar to the environments present in
                stormwater influent pipes, wet ponds and vegetated swales. The highest negative removal rates
                during summertime were observed for bacterial contaminants in all three types of systems. Except
                for SW2, all sites had negative removal efficiencies during summer storms. These results suggest
                that either sources of bacteria exist in these systems during summer, or that regrowth is occurring
                in the systems. Ile use of the indicators, fecal coliforms and E. coli, are useful because they are
                supposed to indicate the presence of fecal contamination, and they are used for classifying surface
                waters for different purposes. However, it is well known that fecal coliforms include
                environmental bacteria that are not of fecal origin, and E. coli is capable of regrowth in the
                environment. The critical question is, what is the public health significance of these elevated
                bacterial indicator levels? Few if any studies have focused on the fate of specific bacterial
                pathogens in stormwater control systems, so it is unknown if these systems are generators of
                pathogens.


                                                                6










                                                 REFERENCES

                   Butler, D., Y. Xiao, S.H.P.G. Karunaratne and S. Ibedchanamoorthy. 1995. The gully
            pot as a physical, chemical and biological reactor. Wat. Sci. Tech. 31: 219-228.
                   Ellis, J.B. and W. Yu. 1995. Bacteriology of urban runoff: The combined sewer as a
            bacterial reactor and generator. Wat. Sci. Tech. 31: 303-310.
                   New Hampshire Department of Environmental Services (NHDES). 1996. State of New
            Hampshire Surface Water Quality Regulations. Env-Ws 430. NHDES, Concord, NH.
                   U.S. Environmental Protection Agency (USEPA). 1993. Guidance Specifying
            Management Measures for Sources of Nonpoint Pollution in Coastal Waters. U.S. EPA, Office of
            Water, Washington, DC.






































                                                         7









                 Table 1. Study sites for stormwater control project

                 Site name                      Location        Acronym         Stormwater control description


                 1. Wall Mart                   Somersworth     SW1             cattail pond

                 2. Wall Mart                   Somersworth     SW2             cattail pond/level spreader

                 3. Shaw's Plaza expansion      Dover           DS              swale; high flow

                 4. Sawtelle parldng lot        Dover           SP              swale; medium flow

                 5.  BJ Wholesale               Portsmouth      BJ              infiltration chambers

                 6.  Costco/JDC property        Portsmouth      CC              level spreader/wetland

                 7.  CellTech                   Portsmouth      PC              swale; medium flow

                 8.  Wall Mart                  Portsmouth      PW1             pond/staggered dike

                 9.  Wall Mart                  Portsmouth      PW2             swale with level spreader

                 1O.Wentworth by the Sea        Newcastle       NM              swale w/storage; low flow
                     condominiums










               Table 2. Sampling conditions at sites.

               Date        Site Sample. time Flow Temp Conductivity                                                 Comments
                                              (1/min) I/E (C) I/E (jumhos)
                1/19/96    SWI     18:20-18:30                 0
                           SW2     18:50-19:15      E- 300     0
                           DS      19:30-19:45                 0
                           SP      20:05-20:15      E:75       0                       much of flow over top from adjacent parking lot
                           BJ      18:10-18:25                 0
                           CC      20:15-20:30      E: 130     0                       1 collected from water entering manhole; good flow through weir
                           PC      17:30-17:45                 0                       1 and swale covered under 10-15'snow; E collected at level spreader
                           PWl     18:30-18:50                 0                       E collected near outlet and inflow from road
                           M       18:55-19:20                 0
                           NM      19:30-19:45                 0                       swale covered with snow; E collected from slush
                                                                                                                                                ... . .... . ..... . .......
                1/24/96    SWI     14:55-15:00                 0
                           SW2     15:20-15:40                 0
                           DS      16:00-16:20                 0
                           SP      16:45-16:55                 0                       much of flow over top from adjacent parking lot
                           BJ      15:25-15:30                 0
                           CC      17:25-17:30                 0                       1 collected from water entering manhole; good flow through weir
                           PC      no 1-15:05                  0                       1 and swale covered under 10-15 snow; E collected at level spreader
                           PWI     15:5;Q_15:55                0
                           PW2     16:05-16:10                 0
                           NM      16:45-no E                  0                       swale covered with snow and E not collected
                4/16/96    SWI     10:20-10:30
                           SW2     10:50-11:05
                           DS      11:20-11:30
                           SP      11:50-11:55                                         much of flow overtop from adjacent parking lot
                           BJ      10:25-10:35
                           CC      10:45-10:55                                         1 collected from inflow pipe; flow through weir
                           PC      11:00-11:10                                         E collected within swale
                           PWI     11:40-11:50
                           PW2     11:25-11:35
                           NM      12.10-12:20
                7/13/96    SWI     11:55-12.05      1: 120  21/22.5
                           SW2     12.10-12:25      E: 240     20.5
                           DS      11:40-11:45                 21
                           SP      11:15-11:20      E: 160  21/21.5                    much of flow over top from adjacent parking lot
                           BJ      12:15-12:25      1:135      20          130/0
                           CC      11:45-11:55      L 150      21.5         0/0        water flowing under weir
                           PC      11:15-11:25                 19.5         0/0        E collected within swale
                           FWl     13:15-13:25                 21        430/320       E collected near outlet and inflow from road
                           PW2     13:30-13-45                20/21     1800/1200
                           NM      no samples                                           no water into or within swale
                   9/8/96  SWI     11:40-11:50
                           SW2     12:10-12:25
                           DS      12:40-12:50
                           SP      no samples                                          not enough water to sample
                           BJ      10:55-11:05                 20                      couldn't open manhole, I collected from adjacent puddle
                           CC      11:10-11:20      1: 1.4     19                      no flow through weir
                           PC      12:25-11:35              18-18.5                    little flow, water at I collected; E collected at level spreader
                           PW1     12:15-12-20                 19                      little flow
                           PW2     12:25-12:40                 20                      no water at E
                           NM      no samples                                          no water at 1; E collected from outfloe pipe to high marsh
 






              Table 3. Meteorological data for A.) sampled storm events;
              B.) monthly totals.

                A.
                Date    Sampling        Storm event    Antecedent dry Prior event
                            time          rainfall      (>0.5") period     rainfall   Comments
                                            (in)             (d)            (in)
              1/19/96  18:10-20:15       0.23+0.08            .5           .28/48h    lost 13" snow/48h
              1/24/96  14:55-17:30       0.55+0.15             3           .31/48h
              4/16/96  10:20-12:20       2.15+0.8              1           0.56/24h
              7/13/96  11:15-13:30       2.8+1.35              2           1.46/48h
              9/8/96 10:55-12:50           0.28                4           0.76/48h   hurricane





                B.
              Month Total rainfall Total snowfall       #events>0.5"
                            (in)            (in)
                Jan         2.74            24            2 (1 snow)
                Feb         1.59             7                 1
                Mar         2.49            20.5          4 (3 snow)
                Apr         6.64             4            6 (1 snow)
                May         3.64             -                 3
                June        1.86             -                 I
                July        7.87             -                 3
                Aug         0.84             -                 I
                Sept        3.6              -                 2








                     Table 4. Non-biological contaminant concentrations at both influent (1) and effluent (E) locations at the 10 sample sites.
                     Averages assume contaminant concentrations below detection limits equal detection limits.
                     Concentrations are mg/l, except for turbidity, which is NTU.

                     Turbidity                   11           IE        21          2E          31          3E          41          Q           51         5E           61         6E          71          7E          81          8E          91               9E     101        WE
                                     1/19196     150          130       76          70          90          58          90          80          22         35           64         78                      25          56          100         3.3              6.8    50         21
                                     1/24/96     89           100       54.5        32.5        82          Ill         20          24          29         35           194        78                      19          74          18.7        5.6              3.5    37
                                     4/16/96     51           27        24          11.6        64          23          75          31          9.1        16.6         21         12.7        1.04        4.8         27          21          18.1             7      51         47
                                     7113196     15           9.3       9.3         8.4         13          12          6.8         6.5         10         9.9          4.5        3.2         1.9         2.3         8.3         7.6         3.3              5.5
                                     2M@         11           14        6.6         3.4         16          300                                 6.8        12           4.1        5.8         -1.7        1.6         7.3         6.6         6.3                                33
                     A Ea
                                                 63           56        34          2S          53          101         48          35          15         22           58         36          1.5         11          35          31          7.3              5.7    46         34
                     Aluminurn                   11           IE        21          2E          31          3E          41          4E          51         SE           61         6E          71          7E          81          BE          91               9E     101        WE
                                     1/19/96     4.72         3.04      1.81        2.27        2.54        1.35        2.76        2.18        0.518      0.98         1.95       2.35                    1.09        1.49        3.71        0.085            0.452  1.06       0.698
                                     1/24/96     2.06         2.1       1.23        0.765       1.76        2.01        0.496       0.422       0.56       1.07         10.5       2.26                    1.05        2.01        0.401       0.093            0.209  1.42
                                     4/16/96     3.67         0.401     0.669       0.21        2.03        0.58        3.65        1.17        0.339      0.604        1.03       0.434       0.065       0.37        1.24        0.994       0.844            0.234  1.31       1.04
                                     7/13/96     0.35         0.055     <0.025      0.036       0.34        0.141       0.182       0.142       0.262      0.341        0.158      0.073       <0.05       0.123       0.253       0.201       0.14             0.49
                                                 0.238        0.1       0.163       0.062       0.219       3.32                                0.472      0.457        0.161      0.199       <0.05       0.136       0.17        0.166       0.215                              0.19
                                                 ............. ............I.........................I.................................. . .......... .................................................................................. . .......................................................................................... ........................................................... ..........I...............................................
                     A.Yna                       2.21         1.14      0.79        0.67        1.38        1.48        1.77        0.98        0.43       0.69         2.76       1.06        0.06        0.55        1.03        1.09        0.28             US     1.26       0.64
                     ...      n
                     Copper                      11           IE        21          2E          31          3E          41          4E          51         5E           61         6E          71          7E          81          8E          91               9E     101        ME
                                     1/19/96     0.036                  0.023       0.021       0.026       <0.0025     0.02        0.0065      0.024      0.013        0.021      0.022                   <0.0025     0.015       0.026       0.109            <0.0025 0.026     0.007
                                     1/24/96     0.018        0.02      0.0145      0.0105      0.026       0.017       0.011       0.008       0.011      0.015        0.059      0.024                   0.008       0.02        0.01        0.006            0.008 0.012
                                     4/16/96     0.023        0.0054    0.008 0.005             0.014       0.0028      0.017       0.0042      0.0034     0.006        0.006      0.0032      <0.0025     0.0027      0.008       0.007       0.006            0.0028 0.01       0.01
                                     7/13/96     0.0059       <0.0025 <0.0025       0.0029      0.0055 0.0046           0.0036      0.0096      0.0026     0.0034       <0.0025 <0.0025        0.0073      0.0096      0.0052      0.0048  <0.0025 <0.0025
                                     9/8/96      0.02         <0.0025 0.011         0.007       0.014 0.022                                     O-OD9      0.011 0.009 0.011                   0.019       0.0042      0.01        0.011       0.009                              <0.0025
                                ..........                                     ..............................--"-* . ... . .....                                                                    ........... ** ...............                              ............. ** *'** ** ***"* -"
                                                 0.021        0.011     0.012       0.009       0.017       0.010       0.013       0.007       0.010      0.010        0.020      0.013       0.010       0.005       0.012       0.012       0.027            0.004 0.016       0.007
                       HIC                       li           IE        21          2E          31          3E          41          4E          51         5E           61         6E          71          7E          81          8E          91               9E     101        1013
                                     1/19/96     0.217        0.186     0.122       0.147       0.222       0.137       0.(Y77      0.11        0.036      0.089        0.058      0.105                   0.103       0.097       0.169       0.041            <0.025 <0.025     0.038
                                     1/24/96     0.108        0.17      0.109       0.0865      0.224       0.163       0.06        0.093       <0.025     0.193        0.169      0.09                    0.082       0.114       0.083       0.031            <0.025 0.034
                                     4/16/96     0.154        0.0595    0.134       0.114       0.126       0.072       0.094       0.036       0.038      0.05         0.043      0.034       0.054       0.07        0.08        0.051       0.066            0.058 0.035       0.088
                                     7/13/96     0.052        0.034     <0.025      0.027       0.104       0.085       <0.025      0.117       <0.025     0.073        <0.025     <0.025      0.179       0.154       0.04        0.03        0.025            0.025
                                     9/8/96      0.284        <0.025    0.132       0.115       0.32        0.43                                0.11       0.223        0.038      0.09        0.686       0.112       0.14        0.149       0.128                              <0.025
                                         ..........i. ......................................................................... . ........................................................................................................................................................................................................................................................................................................................
                                                 .163 0.095             0.104 0.098             0.199       0.177       0.064 0.089             0.047      0.126 0.067             0.069       0.306       0.104       0.094       0.096       0.058            0.033 0.031       0.050
                     Oil &Grease                 11           IE        21          2E          31          3E          41          4E          51         5E           61         6E          71          7E          81          8E          91               9E     101        IOE
                                     1/19/96     19.2         11.61     5.84        5.69        6.41        2.44        7.61        4.67        1.25       2.18         5.05       5.36                    1.17        4.11        8.35        1.28             <1     1.24       1.25
                                     1/24/96     5.41         5.84      3.36        2.74                    5.06        1.16        1.74        1.37       2.17         20         7.4                     3.04        10.22       2.16        1.33             2.22   2.84
                                     4/16/96     8.25         1.98      10.89       1.22        2.64        <1          8.89        1.41        <1         <1           1.1        <1          <1          <1          3.77        1.35        5.42             1.15   1.68       2.4
                                     7/13/96     <1           <1        <1          <1          <1          1.61        <1          <1          <1         1.46         1.49       2.5         3.24        1.81        <1          1.94        3.09             4.4
                                     9/8/96      4.17         1.79      9.24        2.53        3.51        3.88                                2.11       9.48         2.92       1.68        1.26        4.21        2.9         3.96        1.56                               1.29
                                                                               7                            2.90                                i3i
                                                              . .......... ii                                                                                           11         3.59        1.93        2.25        4.40        3.55        2.54             2.19   1.92       1.65











                     Total P                     I I        IE          21          2E           31              3E          41     4E          51          5E              61          6E           71         7E           81     8E               91          9E         101        IOE
                                   1119/96       0.667      0.601       0.361       0.406        0.379           0.270       0.346  0.405       0.074       0.203           0.299       0.361                   0.167        0.314  0.705            0.043       0.093 0.462           0.475
                                   1/24/96       0.513      0.812       0.665       0.439        0.889           1.616       0.624  0.366       0.324       0.475           2.068       1.094                   0.678        0.986  0.319            0.065       0.109      1.038
                                   4/16/96       0.100      0.176       0.237       0.214        0.069           0.059       0.401  0.108       0.028       0.056           0.045       0.029        0.010      0.023        0.047  0.072            0.039       0.022      0.184      0.262
                                   7/13/96'      0.139      0.107       0.132       0.143        0.072           0.061       0.044  0.057       0.057       0.046           0.039       0.031        0.022      0.005        0.063  0.085            0.017       0.053
                                   918196        0.411      0.090       0.165       0.091        0.202           0.-5-4-9................................................0-.0-9-20.-2-22 0.-05 ..10.-I-2-20-.0-I-60-.0-r-7-7 0-...I-0-30.-2-94       0.-I..I-3...............................................0-.-2-2-9
                                                            --iGii      iiii        iiii         i@ii 0.511 0.354 0.234 0.115 0.200 0.500 0.327 0.016 0.190 0.303 0.295 0.055 0.069 0.562 0.322
                     Chloride                    11         IE          21          2E           31              3E          41     4E          51          5E              61          6E           71         7E           81     8E               91          9E         101        IOE
                                   1/19/96       265        1565        832         1156         250             224         102    223         303         342             HY7         658                     213          414    1037             29          9          108        104
                                   1/24/96       71         1010        560         545          128             285         79     140         171         255             12          275                     335          192    385              6           39         120
                                   4/16/96       6          923         432         391          6               12          <2     <2          <2          3               4           8            3          3            5      6                13          33         5          5
                                   7/13/96       <2         83          62          36           2               it          <2     <2          <2          <2              <2          <2           <2         <2           <2     2                <2          2
                                   9/8/96                   39          4           22           25              70                             2           2               2           2            <2         <2           3      22               4                                 1506
                                      --  ............ ii ........... iii ........... iii .......... iii . . .......... ii .............. 1.2.0................46................. 9--2. ................. 9--6 ................121...............25................ 1.8-9. .................2................. I-1-1- .............123..............290............... I-I- ................21................78...............538
                     TN                          li         IE          21          2E           31              3E          41     4E          51          5E              61          6E           71         7E           81     8E               91          9E         101        IOE
                                   1/19196       0.83       2.67        1.38        1.95         0.73            0.61        0.31   0.42        0.33        0.66            0.34        0.46                    0.41         0.32   0.50             0.30        0.25       1.18       1.15
                                   1/24/96       0.65       3.18        2.25        1.50         0.74            0.81        0.69   0.61        0.46        0.87            0.34        0.32                    0.59         0.89   1.32             0.30        0.25       0.85
                                   4116/96       0.23       0.59        0.52        0.70         0.30            0.45        0.29   0.18        0.18        0.35            0.16        0.30         0.13       0.16         0.21   0.20             0.17        0.30       0.54       0.92
                                   7/13/96       0.50       0.25        0.52        0.44         0.35            0.44        0.21   0.29        0.48        0.49            0.28        0.28         0.37       0.45         0.39   0.46             0.25        0.34
                                   9/8/96        1.26       0.53        1.57        0.98         2.72            1.66                           0.63        1.%             0.57        0.27         0.64       0.48         OX     0.83             0.85                              1.30
                                      ............                                  ...........                                                 .............. ..........
                                                 0.69       1."         1.25        1.11         0.97            0.79        0.38   0.37        0.42        0.87            0.34        0.33         0.38       0.42         0.55   0.66             0.37        0.28       0.85       1.12
                                                 11         IE          21          2E           31              3E          41     4E          51          5E              61          613          71         7E           81     BE               91          9E         101        IOE
                                   1/19/96       124        97          64          67           57              38          65     56          <20         31              58          64                      <20          42     100              <20         <20        <20        <20
                                   1/24/96       43         73          43          29           38              58          <20    <20         <20         29              218         64                      30           82     35               <20         <20        <20
                                   4/16/96       59.5       52.5        43          <20          31              <20         106    21          <20         <20             <20         <20          <20        <20          33     23               30          <20        <20        <20
                                   7/13/96       <20        32          21          22           <20             <20         <20    <20         <20         <20             <20         <20          <20        <20          <20    <20              <20         <20
                                   9/8/96        62         30          48          46           43              119                            37          32              <20         21           <20        <20          36     53               43                                38
                                      **  ................a.............. i-7. ............... ii .............. ii .............. ii .............. ii ............... ii .............. i-9. ............... ii .............. ii .............. ii .............. ii .............. i-O. ................. 2--2 ................ ii .............. .............. ii .............. i@ .............. ii ............. ii
                     BOD                         I I        IE          21          2E           31              3H          41     4E          51          5E              61          6E           71         7E           81     8E               91          9E         101        IOE
                                   1/19196       12         11          <10         <10          <10             <10         <10    <10         <10         <10             <10         <10                     <10          <10    <10              <10         <10        <10        <10
                                   1/24/96       4.3        16.7        9.35        5.45         4.1             5           4.4    <3          <3          <3              4.1         4.4                     3.8          8.6    5.9              <3          <3         <3
                                   4/16/96       <3         9.5         5.3         <3           <3              <3          <3     <3          <3          <3              <3          <3           <3         <3           <3     <3               <3          <3         <3         <3
                                   7/13/96       2.7        5.7         4.2         3            3               3           2.1    2.1         1.5         2.4             1.2         < I          <1         1.5          1.2    1.8              < 1         2.7
                                   9/8/96        14.1       2.7         13.8        5A           9.3             16.2                           3.3         14.7            4.5         4.2          2A         2.7          9      14.4             8.7                               4.2
                                          ........... iii ....                                                               .........................................................................I.............................................................................................................I............................................................................ .......
                                                            iii         8.53        5.37         SA              7.44        4.88   4.53        4.16        6.62            4.56        4.52         2.13       4.20         6.36   7.02             5.14        4.68       5.33       5.73
                     Cadmium                     11         IE          21          2E           31              3E          41     4H          51          5E              61          6E           71         7E           81     8E               91          9E         101        IOE
                                   1/19)96       0.0012 0.0011 0.0006 0.0011                     0.001 0.0005 0.0004 0.0007 0.0004 0.0006 O.OOD4 0.0009                                                         0.0006 0.001 0.0019 0.0012 <00025 <00M <00025
                                   If24/96 0.00100 0.00120 O.OD09 0.00060 0.00090 0.00040 <00025 <00025 <00025 0.00035 0.00055 0.00035                                                                          0.00040 0.00055 0.00065 0.0005 <.OD025 <00025
                                   4/16/96 <OW5 0.0005 <0005 <0005 <0005 <0005 <0005 <OD05 <OD05 <0005 <0005 <0005 <0005                                                                                        <0005 <0005 <0005 <0005 <0005 <0005 <0005
                                   7/13/96 <0005 <0005 <0005 <0005 <0005 <0005 <0005 <0005 <0005 <0005 <0005 <0005 <0005                                                                                        <0005 <0005 <0005 <OD05 <0005
                      ................ .... 2ML.0.0005 <0005 O.OW7 <OD05 <0005 <0005                                                       <0005 <.0005 <0005 <0005 <0005                                       <0005 <0005 <0005 O.OW7                                        <0005
                     Average                                                                                                                                                0-0, 0-5*   0' * 0" , 0- *6' 0- *.'0'* '0" '0" * 5- '0" *.* 0** * 0- '0- 0- 0-6- - 0-. , 0- , 0"0", 9- , 0"., '0' Diii 0** , '0" '0' 0' '5- , 0" " 0" '0"0" 5' 0- *0 0*5'







                   Table 5. Fecal coliform and E. coli levels (per 100 ml) at ten stormwater control sites
                                       in Coastal New Hampshire (I=INFLUENT; E=EFFLUENT).


                   FECAL COLIFORMS
                   Date                     SWI          SWI           SW2          SW2         DS              DS    SP        SP        13J      BJ         CC       CC         PC       PC              PWI      PW1          PW2           PW2         NM         NM
                                            11           1E            2I           2E          3I              3E    41        4E        5I       5E         6I       6E         7I       7E              81       8E           9I            9E          101        IOE
                             1/19/96        1320         4             6            20          105             16    50        120       28       1600       90       940                 26              140      125          800           13          5          12
                             1/24/96        860          14            73           21          4               10    80        165       1.5      220        6.5      260                 10.5            35       3            22            6           56
                             4/16/96        340          35.5          27           142.5       520             140   14        25        2.5      460        0.5      0.5        0.5      0.5             9.5      16.5         15            16.5        0.5        0.5
                             7/14/96        1400         18200         10800        3200        940             1080  1800      2000      2        1370       21       400        0.5      4               28600    1000         280           800
                             9/8/96     528000           46000         60000        50000       2000            66000                     38       5600       260      5000       20       1200            5000     16000        16000                                40
                   Z  .. .........................................................................................................................................................................................................................................................................................................................................................
                      eq. mean              3098         278           377          395         210             276   100       177       6        1044       17       190        2        15              367      158          260           32          5          6
                   ................................... I'I'T ............................... 1".0, ..................................... ......................... 0".'6' ...................... @.-6 ......................... 6'.'I ..................... 6.'i ......................i..................................................................................................
                   LE                                                                           0.8                                          1                                                             3                     2.9                       0.6



                   E. coil
                   Date                     SWI          SWI           SW2          SW2         DS              DS    SP        SP        BJ       BJ         CC       CC         PC       PC              PWI      PWI          PW2           PW2         NM         NM
                                            11           IE            21           .2E         3I              3E    41        Q         51       5E         6I       6E         71       7E              81       8E           91            9E          101        IOE
                             1/19/96        1260         2             2            8           95              7     46        60        24       1600       80       920                 25              130      75           60            4           7          2
                             1/24/96        760          3             9            14          1               10    80        165       0.4      220        3.5      260                 10.5            35       3            9.5           5           51
                             4/16/96        300          24.5          6            112.5       500             140   8         15        2.5      390        0.5      0.5        0.5      0.5             8.5      13           7.5           1 1         0.5        0.5
                             7/14/96        1400         17200         9400         2400        900             520   1800      2000      2        1370       20       400        0.5      4               1600     1000         265           600
                             9/8/96         6000         12000         48000        20000       2000            6000                      32       4000       260      2000       5        1200            3600     8000         1000                                 15
                   Z  ............................................................................................................................................................................................................................................................................................................................................................
                      eo. mean              1193         125           137          227         154             125   85        131       4        945        15       157        1        14              186      119          65            19          6          2
                         ............................ @ .6, ................................... 0-6, ... ............................ 1".'2' ........................... 0 .... 6....................... 0 .... O' O. ......................... O."i ...................... 0 .... 1........................ 1 ... 6................................... I ... 7................................. I ... 9.....................


                   FC/Ec
                   Date                     SWI          SWI           SW2          SW2         DS              DS    SP        SP        BJ       BJ         CC       CC         PC       PC              PW1      PWI          PW2           PW2         NM         NM
                                            I I          I E           21           2E          3I              3E    4I        4E        51       5E         6I       6E         7 1      7 E             81       8E           91            9E          101        IOE
                             1/19/96        1.0          2.0           3.0          2.5         1.1             2.3   1.1       2.0       1.2      1.0        1.1      1.0                 1.0             1.1      1.7          13.3          3.3         0.7        6.0
                             1/24/96        1.1          4.7           8.1          1.5         4.0             1.0   1.0       1.0       3.8      1.0        1.9      1.0                 1.0             1.0      1.0          2.3           1.2         1.1
                             4/16/96        1.1          1.4           4.5          i.3         1.0             1.0   1.8       1.7       1.0      1.2        1.0      1.0        1.0      1.0             1.1      1.3          2.0           i.5         1.0        1.0
                             7/14/96        1.0          1.1           1.1          1.3         1.0             2.1   1.0       1.0       1.0      1.0        1.1      1.0        1.0      1.0             17.9     1.0          1.1           1.3
                                            88.0         3.8           1.3          2.5         1.0             11.0                      1.2      1.4        1.0      2.5        4.0      1.0             1.4      2.0          16.0                                 2.7
                                                ........................................................................................ .................................................................................................................................................................................................
                   Averaite                 '-ii.5       2.6           3.6          1.8         1.6             3.5   1.2       1.4       1.6      1.1        1.2      1.3        2.0 1.0                  4.5      1.4          6.9           1.8         0.9        3.2








                    Table 6. Sample concentrations relative to water quality criteria for toxic substances*
                                                  Concentration                              Sites                                         Sites                                      Sites                               Sites
                    Date                                range                     >acute concentration                   acute>sample conc>chronic                       <chronic concentration                    >NURP conc.
                                                        (99/1)
                    Aluminum                                                                 >750                                750>sample conc>87                                   <87                                 NA
                    ..........................................I.............................................................................................................................. ...................................................................................................................................
                                  1/19/96               85-4720                   1-4,6,8i&e 5e,7e,10i                                    5i,9e                                        9i
                                  1/24/96               93-10500                  1-3,6ift Se,%&,10i                               4,9i&e 5i,8e                                      none
                                  4116/96               65-3670                   4,8,10i&e li,3i,6i,9i                         2,5i&e le,3e,6e,7e,9e                                 7i
                                  7/13/96               50-490                               none                                2-5,8,9i&eli,6i,7e                                  le,6e,7i
                    ....................... wn@ .............. 50-3320                         3e                          l,5,6,8i&e 2i,3i,7e,9i,10e                                2e,7i
                                                        .......................................................................................................... .................................................................................................................................................
                    Cadmium                                                                  >0.82                         0.92>sample conc>0.38                                      <0.38                               NA
                    .............................................................................................................................................................................................................................................................................................................
                                  1/19/96               <.25-1.9                   1,8i&c 2e,3i,6e,9i                           5i&e 2i,3e,4e,7e                            10i&e 4i,6i,9e
                                  1/24/96               <.25-1.2                             Ii&e                                2,3,8i&e 600i                              4,5i&e 6e,9e,10i
                                  4116/96               <0.5                                 none                                          none                                  all samples
                                  7/13/96               <0.5                                 none                                          none                                  all samples
                    ....................... Wï¿½i26       <0.5-0.7                             none                                          none                                  all sam
                                          ............................................................................................................................................................................................................. pls@ ........................................................
                    C  P.P                                                                                                       4.6>sample conc>3.5                                  <3.5                                >50
                                                                                             >4.6
                                                                                            .....................................................I........... ................................................................................................................................
                                  1/19/96               2.5-109                 1,2,4-6.8,10i&e 3i,4i.9i                                  none                                       300e                                9i
                                  1/24/96               6.0-59                           all samples                                                                                                                      6i
                                  4/16/96               2.8-23                 1,2,8,10i&e 3i,4i,5e,6i,9i                                 4e                                7i&e 3e,5i,6e,9e                            none
                                  7/13/96               2.5-10                      7,8i&e 100e,                                          3e,4i                               2,5,6,9i&e le                             none
                                  9/8/96                2.5-22                    2,3,5&@j!@S;                                             7e                                         le,10e                              none
                    ...... ...... ......................... .............................................................. ........ ............................................................................ I. ....................................................................
                     Inc                                                                     >35                                 35>sample conc>32                                    <32                                 >418
                           ..................................................................................................................................................................................................................................................................................................
                                  1/19/96               25-222                        1-8i&e 900e                                                                                    9e.10i                              none
                                  1/24/96               25-224                      IA,6,8i&e 50c                                         10i                                        9i&e 5i                            none
                                  4116196               34-154                     1-5,7-9i&e 6i.10e                                      6e,10i                                     none                                none
                                  7/13/96               25-179                     3,7i&e li,4c,5egi                                      le                               2,6,9i&e 4i,5i,8e                            none
                                  MM                    25-686                        all but le&10e                                       none                                       le, l0e                             7i
                    'E@lorlde                           ...........................................................................................................................................................................................................................................................
                                                                                         Zï¿½919%                                  M%                                                                                       NA
                    ....................................................................................................                                                                                   .. . . ........................
                                  1/19/96         9,000-1,565,000                         le,2e,8e                               5i&e le,2i,3i,6e,8i                      4,9,10i&e 3e,6i,7e
                                  1/24)96         6,000-1,010,000                              le                                2i&e 3i,5e,6e,7e,8e                   4,9i&e li,3i,5i,6i,8i,10i
                                  4/16/96         2,000-923,000                                le                                          2i&c                                  li; 3-10i&e
                                  7/13/96         2,000-83,000                               none                                          none                                  all < 84,000
                                  9/8/96          2,000-70,000                               none                                          none                                  all < 84,000
                    *Acute and chronic concentrations for State of New Hampshire criteria for protection of aquatic life; in pg/I (NHDES, October, 1996).
                    NURP concentrations for mean runoff concentrations for commercial land use.









                 Table 7. Contaminant concentrations relative to NURP estimates
                 for runoff from commercial land use.
                                                                   Concentration                                      Sites with
                 Date                                                     range                              >NURP concentrations
                 Tota!.&ï¿½jp                                                                                                >219
                                   !@qE@j   ............................................... .... . ..................................
                                            1/19/96                   0.043-0.667                                          none
                                            1/24/96                   0.065-2.07                                           none
                                            4/16/96                   0.010-0.262                                          none
                                            7/13/96                   0.017-0.143                                          none
                                            9/8/96                    0.016-0.549                                          none
                 ..... ...............................                                              ....................
                 lotal-nitrogen      ...... . ..... . .....e.......... . ...................... .................................... >1.5     ............
                 ........... ........... . .....
                                            1/19/96                   0.249-2.66                                           le, 2e
                                            1/24/96                   0.250-3.18                                           le, I
                                            4/16/96                   0.130-0.697                                          none
                                            7/13/96                   0.211-0.522                                          none
                                            9/8/96                    0.271-2.72                                     2i, 3i, 3e, 5e
                 I. B;E6 .......................            ............................          .........  ......................................................................
                                                                          (                                                >14
                                            1/19/96                       <10-12                                           none
                                            1/24/96                       <3-16.7                                           le
                                            4/16/96                       <3-9.5                                           none
                                            7/13/96                       <1-5.7                                           none
                                            9/8/96                        2.4-16.2                                   1 i, 3e, 5e, 8e
                         ..................                                                                                                .................
                                                                                                                           >84
                                                                                                                           .................  .......................
                                            1119N6                        <20-124                                      li, le, Se
                                            1/24/96                       <20-218                                           6i
                                            4/16/96                       <20-106                                           4i
                                            7/13/96                       <20-32                                           none
                                            9/8/96                        <20-119                                           3e
                 ..... ...............................                                                .............................................e..............................
                                                                          NTU                                         <IONTU*
                                            . ............................           ................................                          ...........
                                            1/19/96                       3.3-150                                           9i
                                            1/24/96                       3.5-194                                          9i&e
                                            4/16/96                       1.04-75                                     5i,7i&e,9e
                                            7/13/96                       2.3-15                            all samples except li,3i&e
                                            9/8/96                        1.6-300                      all samples except 1,3i&e 5e,10e
                                                                                                                           ..... . ... ..
                 Zi-a-ni     ....................                                                      ............... ............. <10*.*........................
                                                                                        . .. . ........... . .. .........          . ............. . ..........
                                            1/19/96                       <1-19.2                            all samples except li&e
                                            1/24/96                       1.16-20.0                            all samples except 6i
                                            4/16/96                       <1-10.89                              all samples except I
                                            7/13/96                       <1-4AO                                      all samples
                                            9/8/96                        1.26-9.48                                   all samples
                 *Assuming no measureable turbidity under naturally occurring conditions, a value of 10 NTU
                 would be required to meet Class B water criteria.
                 **A concentration of 10 mg/l was arbitrarily chosen for comparitive purposes.









               Table 8. Bacterial concentration ranges relative to classification criteria.



                                        Concentration            Sites with high*                  Sites with low**
               Date                         range                concentrations                      concentrations
               Fecal coliforms           cfu/100 ml                    >88                                <14
                                                                                            
                             1/19/96       4-1600             6,8i8&e li,3i,4e,5e,9i                10i&e, le,2i,9e
                             1/24/96       1.5-860                 li,4e,5e,6e                    3i&e, 5i,6i,7e,8e,9e
                             4/16/96       0.5-520                Me, li,2e,5e                      6,7,10i&e 5i,8i
                             7/13/96     0.5-28600              1-4,8,9i8&e 5e,6e                       5i,7i8q&e
                             9/8/96      20-528000             1-3,8i&e 5e,6e,7e,9i                      none
                                                                                                                            
               E. coli-                    cfu/100 ml                   >126                                <47
                             . ......... . ................ .............................          . ...........................................................
                             1/19/96       2-1600                  li,5e,6e,8i                 2,10i&e le,3e,4i,5i,7e,9e
                             1/24q/96       0.4-760                 li,4e,5e,6e                  3,9i&e le,2i,5i,6i,7e,8e
                             4/16/96       0.5-500                li,2e,5e,3i&e                    6-10i&e 2i,4i,5i
                             7/13/96     0.5-17200              14,8i&e 5e,6e                        5i, 7i&e
                             9/8/96        5-48000             1-3,6,8i&e 5e,7e,9i                        7i


               *The high fecal coliform level is the concentration at which shellfish growing areas are classified as prohibited.
               The high E. coli level is the concentration at which Class B water classification criteria are violated.
               "The low fecal coliform level is the concentration at which shellfish growing areas are classified as approved.
               The low E. coli level is the concentration at which Class A water classification criteria are met.
 






              Table 9. Measured and estimated* removal efficiencies of contaminants in stormwater control systems.


              Overall                  Wet ponds                                                       Vegetated swales                                        Infiltration chamber
                                                      Estimated      Average                                                Estimated       Average                . Estimated
              Site:       SWI SW2 PW1               CC %removal %removal               PW2 PC             DS      SP   NM   %removal %removal                  BJ    % removal
              COD            8         16  -8       44     40            15                 25   -10      -35     45   -30       40             -1             -13       65
              turbidity     11         26  11       38     60            22                 22   -581     -90     26   27        65             -119           40        75
              zinc          42         6   -2       -3     60            11                 43   66       11      -39  -61       60             4              -168      65
              total P        2         17  3        35     45            14                 -25  -1073    -59     34   43        40             -216           -74       65
              total N      -108        11  -19      4      35            -28                24   -10      18      0    -31       40             0              -108      60



              Winter                   Wet ponds                                                       Vegetated swales                                        Infiltration chamber
                                                      Estimated      Average                                                Estimated       Average                  Estimated
              Site:      SW1 SW2         PWI        CC %removal %removal              PW2 PC           DS         SP NM     %removal %removal                  BJ % removal
              COD               -2     10     -9    54     40            13                 0 NA             -1   11      0      40             2              -50       65
              Turbidity         9      44     61    58     60            43                 56 -1044         8    42     -7      65             -189           -35       75
              Zinc              12     17     31    42     60            26                 14     41        33   16   -155      60             -26            -286      65
              Total P        -61       28     62    47     45            19                 -26  -3268      -75   54     57      40             -651           -51       65
              Total N       -330 '     20  -39      -23    35            -93                -16  -191       -22   20   -33       40             -48            -90       60



              Summer                   Wet ponds                                                       Vegetated swales                                        Infiltration chamber
                                                      Estimated      Average                                                Estimated      Average                   Estimated
              Site:      SWI SW2         PWI        CC %removal %removal               PW2    PC       DS         SP NM     %removal %removal                  BJ % removal
              COD               24     1   -30      -2     40            -2                 37       0    -121      0 NA         40             -21                9     65
              Turbidity         6      30     11    33     60            .20                16   -274     481     26 28          65             -137           -51       75
              Zinc              73     10     -5    -52    60            7                  64      78      -17   -39 -20        60             13             -122      65
              Total P           42     27  45       18     45            11                 17   -719     -102    34 51          40             -144           -104      65
              Total N           -1     26     2     34     35            15                 53      12       33     0 42         40             12             -169      60
              *EPA estimates based on published studies (6217 guidelines, 1993).







               Table 9. Measured and estimated* removal efficiencies of contaminants in stormwater control systems.


               Overall                  Wet ponds                                                      Vegetated swales                                        Infiltration chamber
                                                       Estimated     Average                                                Estimated      Average                  Estimated
               Site:       SWI SW2        PW2        CC %removal %removal              PW1 PC             DS      SP   NM   %removal % removal                 BJ   % removal
               COD              8   16     25        44    40            23               -8      -10     -35     45   -30       40            -8              -13       65
               turbidity        11  26     22        38    60            24               11     -581     -90     26   27        65            -122            -40       75
               zinc             42  6      43        -3    60            22               -2      66      11      -39  -61       60            -5              -168      65
               total P          2   17     -25       35    45            7                3     -1073     -59     34   43        40            -211            -74       65
               total N      -108    11     24        4     35            -17              -19     -10     18      0    -31       40            -9              -108      60


               Winter                   Wet ponds                                                      Vegetated swales                                        Infiltration chamber
                                                       Estimated     Average                                                Estimated      Average                  Estimated
               Site:      SWI SW2         PW2        CC % removal % removal            PW1 PC          DS         SP NM     %removal %removal                  BJ % removal
               COD              -2      10     0     54    40            16                 -9 NA            -1   11      0      40            0               -50       65
               Turbidity        9       44   56      58    60            42                 61 -1044         8    42     -7      65            -188            -35       75
               Zinc             12      17   14      42    60            21                 31        -41    33   16   -155      60            -23             -286      65
               Total P          -61     28 -26       47    45            -3                 62  -3268        -75  54     57      40            -634            -51       65
               Total N          -330    20 -16       -23   35            -87              -39     -191       -22  20   -33       40            -53             -90       60



               Summer                   Wet ponds                                                      Vegetated swales                                        Infiltration chamber
                                                       Estimated Average                                                    Estimated Average                       Estimated
               Site:     SW1 SW2          PW2        CC % removal % removal            PW1      PC     DS         SP NM     %removal % removal                 BJ % removal
               COD              24      1    37      -2    40            15               -30         0   -121      0 NA         40            -38                9      65
               Turbidity        6       30   16      33    60            21                 11    -274    -481    26 28          65            -138            -51       75
               Zinc             73      10   64      -52   60            24                 -5        78     -17  -39 -20        60            -1              -122      65
               Total P          42      27   17      18    45            26               -45     -719    -102    34 51          40            -156            -104      65
               Total N          -1      26   53      34    35            28                 2         12     33     0 -42        40            1               -169      60
               *EPA estimates based on published studies (6217 guidelines, 1993).








               Table 10. Removal efficiencies (% removal) for contaminants in different stormwater control systems.

               Overall                               Wet ponds                                               Vegetated swales                                Infiltration chamber
                              Site:      SW1 SW2         PW2      CC    Average             PWI       PC       DS        SP      NM      Average             BJ
               Aluminum                  48      14      -26      61        25              -6        -907     -7        45      49          -165            -60
               Cadmium                   -3      -5      24       -18       .1              -39       0        32        -22     0           .6              -2
               Copper                    46      21      85       36        47              -1        44       43        45      59          38              3
               Fecal coliform            91      -5      88       -989      -204            57        -752     -31       -77     -20         -165            -17216
               E. coli                   90      -65     71       -956      -215            36        -1241    19        -54     56          -237            -21677
               Oil and grease            42      57      .14      41        38              19        -23      17        53      14          16              -142
               Chloride                  -940    -14     -92      -6"       -423            -136      -4657    46        -98     -593        -1106           -26
               BOD                       -26     37      9        1         5               -10       -97      -27       7       -8          -27             -59


               Winter                                Wet ponds                                               Vegetated swales                                Infiltration chamber
                              Site:      SWI     SW2 PW2 CC             Average             PWI       PC       DS        SP      NM      Average             BJ
               Aluminum                  24      0       -271     63        -46             -17       NA       22        20      44          17              -90
               Cadmium                   -5      -14              -39       -19             -65                50        -86                 -33             -B
               Copper                    17      16      91       43        42              -3        NA       63        53      63          44              20
               Fecal coliform            99      2       93       -1944     -437            72        NA       38        -122    28          4               -9055
               E. coli                   100     -149    81       -2823     -698            78        NA       14        -64     89          29              -19049
               Oil and grease            29      8       -23      49        16              27        NA       41        27      39          33              -66
               Chloride                  -666    -22     -37      -684      -352            -135      NA       -35       -101    9           -65             -26
               BOD                       -70     20      0        -2        -13             15        NA       -6        10      -54         -9              0


               Summer                                Wet ponds                                              Vegetated swales                                 Infiltration chamber
                              Site:      SW1     SW2 M CC               Average             PW1       PC       DS        SP      NM      Average             Bi
               Aluminum                  74      48      -176     15        -10             13        -159     -519      22      NA          -161            -9
               Cadmium               all below detection limits                                             all below detection limits                       all below detection limits
               Copper                    81      27      57       -17       37              -4        48       -36       -167    NA          -40             -24
               Fecal coliform,           -6      50      -186     -1814     -489            67        -2091    -516      -11     NA          -638            -31672
               E. coli                   -396    67      -126     -1140     -399            -18       -4282    -32       -11     NA          -1086           -29162
               Oil and grease            46      66      -89      5         7               -51       -34      -22       0       NA          -27             -252
               Chloride                  -1933   12      33       0         -472            -380      0        -200      0       NA          .145            0
               BOD                       50      53      44       9         39              -59       -24      -56       0       NA          -35             -256








            Table 10F. Removal efficiencies (% removal) for contaminants in different stormwater control systems.

            Overall                                 Wet ponds                                                  Vegetated swales                                    Infiltration chamber
                            Site:       SWI SW2 PWI                  CC  Average              PW2       PC        DS        SP        NM     Average               BJ
            Aluminum                    48      14      -6           61      30               -26       -907      -7        45        49         -169              -60
            Cadmium                     -3      -5      -39          -18     -16              24        0         32        -22       0          7                 -2
            Copper                      46      21      -1           36      26               85        44        43        45        59         55                3
            Fecal coliform              91      -5      57           -989    -211             88        -752      -31       -77       -20        -158              -17216
            E. coli                     90      -65     36           -956    -224             71        -1241     19        -54       56         -230              -21677
            Oil and grease              42      57      19           41      40               14        -23       17        53        14         15                -142
            Chloride                    -940    -14     -136         -W      -433             -92       -4657     -46       -98       -593       -1097             -26
            BOD                         -26     37      -10          1       0                9         -97       -27       7         -8         -23               -59

            Winter                                  Wet ponds                                                  Vegetated swales                                    Infiltration chamber
                            Site:       SWI     SW2     PW1 CC           Average              PW2       PC        DS        SP        NM     Average               Bi
            Aluminum                    24      0       -17          63      17               -271      NA        22        20        44         -46               -90
            Cadmium                     -5      -14     -65          -39     -30                                  50        -86                  -18               -13
            Copper                      17      16      -3           43      18               91        NA        63        53        63         67                20
            Fecal coliform              99      2       72           -1944   .443             93        NA        38        -122      .28        9                 -9055
            E. coli                     100     -149    78           -2823   -6"              81        NA        14        -64       89         30                -19049
            Oil and grease              29      8       27           49      28               -23       NA        41        27        39         21                -66
            Chloride                    -666    -22     -135         -684    .377             -37       NA        -35       -101      9          -41               -26
            BOD                         -70     20      15           -2      .9               0         NA        -6        10        -54        -13               0

            Summer                                  Wet ponds                                                  Vegetated swales                                    Infiltration chamber
                            Site:       SWI     SW2 PWI CC               Average              PW2       PC        IDS       SP        NM     Average               BJ
            Aluminum                    74      48      13           15      37               -176      -159      -519      22        NA         -208              -9
            Cadmium                all below detection limits                                                 all below detection limits                           all below detection limits
            Copper                      81      27      -4           -17     22               57        48        -36       -167      NA         -25               -24
            Fecal coliform              -6      50      67           -1814   426              -186      -2091     -516      -11       NA         -701              -31672
            E. coli                     -396    67      -18          -1140   -372             -126      -4282     -32       -11       NA         -1113             -29162
            Oil and grease              46      66      -51          5       16               -89       -34       -22       0         NA         -36               -252
            Chloride                    -1933   12      -380         0       -57S             33        0         -200      0         NA         -42               0
            BOD                         50      53      -59          9       13               44        -24       -56       0         NA         -9                -256







                             SvV1N1


                              G)
                           DSE





                              DSP


         DURHAM                           MAINE




                                      PBJ
                                                                      4305-
                                       PCC

                     GREAT SAY


                                                        NCWM
                                        PORTSN V TH
                                               PWM
                              NEW HAMPSHIRE





        ERW


                                             ATLANTIC OCEAN



                                                                      4255-


                                 YD
                                                        10 km





              7055                            7045




         Figure 1. Study sites for the stormwater control project: 1995-96.










                             Figure 2. Geometric mean fecal coliform concentrations in influent and effluent
                                                                   water.



               IOWO








                1000 -








                 100 -








                  10 -










                                                        9                   9
                                                        0-@                 U
                                                                                             04        A4










                                      Figure 3. Geometric mean E. coli concentrations in influent and effluent water.


                     IOM








                      1000








                       100








                       10










                                                                                                                     .4  9       C@   9
                                         C@
                                                     n                                         U
                                                                                               U




                                                                                                                                                                          F












































                                                        ------    -       - -     --- ----     -     -- -
                                                                            DATE DUE

























                                                             GAYLORD No. 2333                      PRINFrED IN U.S.A.








                                                                    1 11111111                111 Hill lill ,
                                                                      - 3 6668 -1410-6 1723 -