:prepared for Commonwealth of Pennsylvania Department of Environmental Resources and Erie County Department of Planning/by Northwest Institute of Research-Woodruff, Inc. as a consortium. V. 8. Sixteenmile Creek and Twentymile Creek Watersheds Erie (Pa.)Dept. of Planning. Pennsylvania.Dept. of Environmental Resources. Northwest Institute of Research -- Woodruff, Inc. [S.l.:The Institute],1981. Storm sewers Pennsylvania Erie County. Water quality management Pennsylvania Erie County. RM WATER M N GEMENT C) Un ........... ......................... C@l ........... ......... SIXTEENMILE CREEK AND TWENTYMILE CREEK VOLUME 8- ERIE COUNTY DEPARTMENT OF PLANNING COMMONWEALTH OF PENNSYLVANIA r' 0J.4 rA T'D J4. 665 4i. S76 1981 v.8 4 STO PLAN AMS lo OCTOBER 1981 PREPARED BY NORTHWEST INSTITUTE OF RESEARCH WOODRUFF, INC. WATERSHED ADVISORY COMMITTEE Member Representing Joyce Andrews Lake City Borough Delores Bendig Lawrence Park Township Gerald Blanchfield Harborcreek Township Harold Crane, Jr. Elk Creek Township Frank Fenton North East Township John Gresch Platea, Borough LeRoy Gross Erie County Conservation Dist. Ted Guzzy Girard Township Richard P. Hessinger Summit Township John Klier Fairview Township Earl Koon Washington Township Roger C. Latimer Fairview Borough Rose Little McKean Township Jacob Luke Greenfield Township -ISI Kenneth Maas North East Borough Paul Martin Millcreek Township Wasinder Mokha Erie City Jeanne O'Brien McKean Borough Wilbur Osborn Waterford Township Lawrence Pieper Franklin Township Cr\ Norman H. Rabell Conneaut Township Mary B. Ripley Wesleyville Borough Robert Smith Greene Township Ronald VanTassell Springfield Township Larry Wygant Girard Borough ERIE COUNTY DEPARTMENT OF PLANNING David Skellie Acting Director Thomas DeBello Senior Planner Jeffrey Spaulding Transportation Planner LI Gilbert Rocco Project Planner A. Latif Panhwar PlanniAg Analyst Dolores Oblinski Draftsman 11 Lori Prody Executive Secretary Kathleen Anderson Secretary This study was financed through a planning assistance grant from the National Oceanic and Atmospheric Administration as administered through the Pennsylvania Department of Environmental Resources Coastal Zone Management Office (Office of Resources Management), and the Erie County Department of Planning. STORM WATER MANAGEMENT PLAN SIXTEENMILE CREEK AND TWENTYMILE CREEK WATERSHEDS Volume 8 Prepared For Commonwealth of Pennsylvania Department of Environmental Resources and Erie County Department of Planning Prepared By Northwest Institute of Research - Woodruff, Inc. As a Consortium October 1981 TABLE OF CONTENTS Page Section I SUMMARY AND RECOMMENDATIONS 1-1 Section 2 BACKGROUND 2-1 Section 3A DESCRIPTION OF THE SIXTEENMILE CREEK WATERSHED 3A-1 3.1 Local Input Data 3A-1 3.1.1 Significant obstructions 3A-1 3.1.2 Existing drainage problem areas 3A-2 3.1.3 Existing storm sewers 3A-2 3.1.4 Proposed storm sewers 3A-3 3.1.5 Existing and proposed flood control projects 3A-3 3.2 Present and Projected Land Use 3A-3 3.3 Soil Types 3A-3 3.4 The National Flood Insurance 100-Year Flood Plain 3A-4 Section 3B DESCRIPTION OF THE TWENTYMILE CREEK WATERSHED 3B-1 3.1 Local Input Data 3B-1 3.1.1 Signif icant obstructions 3B-1 3.1.2 Existing drainage problem areas 3B-2 3.1.3 Existing storm sewers 3B-2 3.1.4 Proposed storm sewers 3B-3 3.1.5 Existing and proposed flood control projects 3B-3 3.2 Present and Projected Land Use 3B-3 Section 4 STANDARDS AND CRITERIA FOR STORM WATER MANAGEMENT 4-1 4.1 Definition of Design Storm 4-1 4.2 Definition of Type I and Type 2 Channels 4-1 4.3 Criteria for Type 1 Channels (Main Stream) 4-2 4.4 Criteria for Type 2 Channels (Branch Streams) 4-2 Section 5 IMPLEMENTATION 5-1 5.1 Introduction 5-1 5.2 Special Considerations 5-1 5.3 Building Permit Process 5-2 5.4 Subdivision Review Process 5-3 5.5 Conclusions 5-3 Section 6 THE SIXTEENMILE CREEK COMPUTER MODEL 6-1 6.1 Existing Stream Characteristics 6-1 6.2 Post-Development Stream Characteristics 6-1 TABLE OF CONTENTS (Continued) Appendix A Tables and Plates Table 8-1 Significant Obstructions, Sixteenmile Creek Table 8-2 Storm Drainage Problems, Sixteenmile Creek Table 8-3 Proposed Storm Water Collection Systems, Sixteenmile Creek Table 8-4 Storm Water Collection and Control Facilities, Sixteenmile Creek Table 8-5 Project Development and Construction Schedule and Costs, Sixteenmile Creek Table 8-6 Existing Flood Control Projects, Sixteenmile Creek Table 8-7 Proposed Flood Control Projects, Sixteenmile Creek Table 8-8 Watershed Runoff Data, Sixteenmile Creek Table 8-9 Significant Obstructions, Twentymile Creek Table 8-10 Storm Drainage Problems, Twentymile Creek Table 8-11 Proposed Storm Water Collection Systems, Twentymile Creek Table 8-12 Storm Water Collection and Control Facilities, Twentymile Creek Table 8-13 Project Development and Construction Schedule and Costs, Twentymile Creek Table 8-14 Existing Flood Control Projects, Twentymile Creek Table 8-15 Proposed Flood Control Projects, Twentymile Creek Table 8-16 Various On-Site Storm Water Control Methods Table 8-17 Advantages and Disadvantages of Various On-Site Storm Water Control Measures Plate 8-1 Sixteenmile Creek Watershed Base Map Plate 8-2 Sixteenmile Creek Watershed Significant Obstructions Map Plate 8-3 Sixteenmile Creek Watershed Drainage Problem Areas Plate 8-4 Sixteenmile Creek Storm Sewer Systems Plate 8-5 Sixteenmile Creek Watershed Flood Control Projects Plate 8-6 Sixteenmile Creek Watershed Existing Land Use Plate 8-7 Sixteenmile Creek Watershed Ultimate Land Use Plate 8-8 Sixteenmile Creek Watershed Soil Map Plate 8-9 Sixteenmile Creek Watershed 100-Year Flood Plain Plate 8-10 Sixteenmile Creek Watershed Subwatershed Map Plate 8-11 Twentymile Creek Watershed Base Map Plate 8-12 Twentymile Creek Watershed Significant Obstructions Map Plate 8-13 Twentymile Creek Watershed Storm Drainage Problems Plate 8-14 Twentymile Creek Watershed Storm Sewer Map Plate 8-15 Twentymile Creek Watershed Flood Control Projects Appendix B Calculations to Determine Increased Runoff and Examples of Specific On-Site Storage ii Section I SUMMARY AND RECOMMENDATIONS This document has been prepared in accordance with the provisions of the Pennsylvania Storm Water Management Act, P.L. 864, Act 167, October 4, 1978 and is a pilot study under that Act. The Northwest Institute of Research of Erie, Pennsylvania and Woodruff Incorporated, Consulting Engineers of Cleveland, Ohio have formed a consortium for the purpose of developing a pilot storm water management plan for the Lake Erie and Elk Creek Watersheds. This study has been prepared under the direction of the Pennsylvania Department of Environmental Resources, Bureau of Dams and Waterway Management, Division of Storm Water Management and the Erie County Department of Planning. This report is Volume 8 in a series of 14 volumes prepared for the Erie County Department of Planning. The purposes of this report are: 1. To establish as base conditions the existing land use and the existing storm water runoff in the Sixteenmile and Twentymile Creek Watersheds against which future conditions can be compared. 2. To calculate the runoff from a projected land use to indicate how much more flow the main stream and its branches would be required to carry. 3. To present a set of criteria and standards for storm water management in this watershed. 4. To recommend the one or more alternative storm water management methods best suited to the needs of the Sixteenmile and Twentymile Creek Watersheds. The standards and criteria which are to be applied to storm water runoff have been summarized in Section 4 and are described in complete detail in Volume 1. It is recommended that these standards and criteria be adopted by the committee in the Sixteenmile and Twentymile Creek Watershed Areas. The various means of implementing these standards and criteria are discussed in Section 5. It is recommended that the on-site approach to storm water management as described in Section 5 be adopted immediately and included in all future development plans. Immediate steps are to be taken so that the Sixteenmile and Twentymile Creek Watershed Areas will be prepared for the tremendous growth that will occur should the U.S. Steel proposal for Springfield Township come to f ruition. It should be emphasized that this storm water management plan is intended solely to minimize the creation of new flood problem areas as a result of increased runoff due to development. Also, existing problem areas will not be aggravated by increased runoff. In this way, the municipalities will be able to concentrate on solutions for those flooding problems that presently trouble local property owners. 1-1 Section 2 BACKGROUND The basic approach to storm water management in the past has been to achieve maximum convenience at an individual site by getting rid of any excess surface water after a rainfall as quickly as possible. This removal is accomplished typically by disposal of the water through a storm sewer or other closed system. As the land in a given area becomes more and more developed, this policy has led to the following problems: 1. Flooding due to overland flow. 2. Increasingly frequent downstream flooding. 3. Diminished groundwater supplies. 4. Erosion of stream banks. 5. Siltation and pollution of streams. As land development continues, the percentage of impervious land surface increases as paved roads, sidewalks, parking lots, and other structures are built. The result of this change is to further aggravate the problem. Areas that previously had no flooding begin experiencing problems and areas which might have been prone to flooding earlier now experience an even more severe problem. The solution of passing one's own water problems downstream is no longer acceptable. The potential damage created by such an approach cannot be tolerated as developments continue to move into once rural areas. Clearly, a new approach to handling storm water runoff is needed. A storm water management plan is necessary that protects our land and streams as well as permits reasonable development. The new approach must strike a balance between local convenience and protection against the hazard of flooding. One significant feature of the approach presented in this document will be the planned detention of water on-site in various types of storage facilities. Such structures will hold the water and release it slowly over time, after the danger of flooding is past. In the process, downstream areas will be protected. This concept will be discussed more fully in the following pages and will be applied to the specific requirements of the Sixteenmile and Twentymile Creek Watersheds. 2-1 Section 3A DESCRIPTION OF THE SIXTEENMILE CREEK WATERSHED On Plate No. 8-1(1) the base map for the Sixteenmile Creek Watershed Area is presented. Also included are the watersheds for Orchard Beach Run, Middle Run, unnamed creek no. 14, Dewey Run, unnamed creek nos. 15, 16, and 17. These direct drainage areas are discussed in further detail in Volume 1 of this study. On this map, major topographic features of the watersheds are shown. The SiXteenmile Creek Watershed is located primarily in the Township of North East and the Borough of North East with a very small portion in Greenfield Township and New York State. It covers an area of approximately 12,400 acres. Sixteenmile Creek has been determined to be a site of natural significance by the Western Pennsylvania Conservancy. For this reason, it should be preserved or improved as much as possible by both government and private concerns. 3.1 Local Input Data There are five types of local data which have been considered in the description of the Sixteenmile Creek Watershed Area. These include: 1. Significant obstructions 2. Existing drainage problems 3. Location of existing storm sewers 4. Proposed storm sewers 5. Existing and proposed flood control projects Each of these types of data are discussed in the following paragraphs. This information is as complete as possible at the time of writing. Additional information may be added as it becomes available. 3. 1.1 Significant obstructions A significant obstruction is defined as any structure or assembly of materials which might impede, retard or change the flow of storm water runoff. Significant obstructions in the Sixteenmile Creek Watershed were located both by surveys conducted by the consultant and by local input from municipal and county officials as well as the Advisory Committee composed of representatives from the affected municipalities. Those obstructions which were identified are described on Table 8-1 and located on the map presented on Plate No. 8-2. A total of 20 obstructions were mapped. These include many bridge abutments and piers or culverts through which the main stream or side branches pass as they flow under highways, driveways and railroads. While many of these structures do not obstruct normal flow, all may be considered potentially obstructive during severe storms if debris is allowed to collect in culvert openings or around bridge piers. They also serve as potential entrapments for ice floes. (l)For the convenience of the reader and to facilitate locating of tables and maps, all of these illustrations are placed in order in Appendix A at the end of this report. 3A-1 The importance of these obstructions is obvious since anything which interferes with the natural flow of the stream can contribute to local flooding under storm conditions. The control of increased runoff due to development that would result from the implementation of this storm water management plan will insure that these structures will operate hydraulically at their present levels. Thus, if a particular structure has no recurrent problems in passing stream flows at the present time, no problems would be expected in the future under the plan as development proceeds. Flooding problems due to structures of insufficient hydraulic capacity will not get worse in the future, nor will they be eliminated by the institution of these storm water management policies. The intent of this plan is to maintain the status quo regarding stream flow. 3.1.2 Existing drainage problem areas There were 6 drainage problems identified in the Sixteenmile Creek Watershed. As indicated in Table 8-2 and shown on Plate No. 8-3, these problems involve primarily either roadways flooding or culvert inlet flooding. Solutions suggested range from increasing culvert size to providing proper drainage. Caution must be taken when incorporating these or any other solutions to insure that no flooding problems are created downstream. The only problem not involving roadway or culvert inlet flooding is located in North East Township at the mouth of the creek on Lake Erie. Ice jams and sand bars are a recurrent problem here which produce substantial flooding. Under emergency conditions, the responsibility to take corrective action falls first on the local municipality. It is recommended that the local municipalities in this case make advance arrangements with all involved agencies and individuals to obtain all required permits, permission to enter private property, etc. in order to regularly remove ice and sand in the creek. If the municipalities do not have the means to handle a particular situation, they should turn first to the Erie County Emergency Management Agency. This office is presently under the direction of Mr. James Smith (telephone (814) 454- 5811). Problems that go beyond the capabilities of this agency should be referred to the Pennsylvania Emergency Management Agency, Western Region Office in Indiana, Pennsylvania. This is presently under the direction of Mr. Carl Keuhn (telephone: (814) 357-2990). The United States Army Corps of Engineers is available for technical assistance only. It is their policy to become further involved only in the most hazardous of cases. As other drainage problems are identified in the Sixteenmile Creek Watershed Area, they can be added to Table 8-2 and Plate No. 8-3. 3.1.3 Existing storm sewers The third type of local input involved the location of all existing storm sewers in the Sixteenmile Creek Watershed Area. This information is shown on Plate No. 8-4. These data can be obtained by consulting the comprehensive plans for the North East Area. 3A-2 At the present time, barring evidence to the contrary, the assumption is made that none of these storm sewers has a significant impact on the management of storm water in this area. 3.1.4 Proposed storm sewers Tables 8-3, 8-4 and 8-5 are provided for the purpose of listing and locating all proposed storm sewers in the Sixteenmile Creek Watershed Area. At the time of writing this report, no new storm sewers are known to have been proposed for the Sixteenmile Creek area. The tables are provided so that information can be added to them and Plate No. 8-4 as it becomes available. Further information on storm sewers can be obtained by consulting the Comprehensive Plan for the North East Region. 3.1.5 Existing and proposed flood control projects Plate No. 8-5 and Tables 8-6 and 8-7 are provided for the purpose of entering the location and description of all existing and proposed flood control projects. Three existing flood control projects were identified in North East Township. There are no known proposed flood control projects for the Sixteenmile Creek Watershed. 3.2 Present and Projected Land Use Present land use is shown on Plate No. 8-6. Existing land use data was taken from the Erie County Land Use Plan Update (June, 1978). It can be seen from the existing land use map that the area is at present generally residential in North East Borough and the remainder of the watershed is a mixture of open land, wooded land and agricultural uses. Projected land use was derived from various Erie County projections. This is shown on Plate No. 8-7. As can be seen, the Sixteenmile Creek Watershed Area is seen as an area of extremely high potential growth. The northern half of the watershed is expected to become residential and the southern half is expected to become residential-agricultural in character. 33 Soil Types The various soil types found within the Sixteenmile Creek Watershed Area are shown on Plate No. 8-8. These soils include the following: 1. Gravelly and sandy soils of the beach ridges (Conotton-Ottawa- Fredon). 2. Deep, medium-textured soils in slightly limy till of the glaciated upland (Volusia-Mardin). 3. Shallow, medium-textured soils of the glaciated upland and the lake plain (Allis-Ellery and Alden). 3A-3 3.4 The National Flood Insurance 100-Year Flood Plain The 100-year flood is defined as the highest level of flooding that is likely to occur on the average, every 100 years. The fact that an area has not flooded recently does not mean it will not do so in the future. The probability of such an occurrence is I percent in any given year. The Flood Plain Management Act, Act 166, October 4, 1978, prohibits development within designated flood plains. No development is allowed in any areas 50 feet or less from the boundaries of designated flood plains. This is intended to reduce flood damage and accumulation of debris due to the 100 year flood and is consistent with the intent of the Storm Water Management Act. On Plate No. 8-9, the flood plain for the basic or 100-year flood is shown. The information was taken from the National Flood Insurance Program Maps (Available for reference at the Erie County Planning Department office). The flood plain is largely confined to the gorge of the Sixteenmile Creek and does not affect any presently developed areas. The only exception to this is in the borough of North East. The flood plain becomes rather wide in this area and threatens developed areas within the Borough. It is essential that the Storm Water Management Plan be enacted in order to prevent future flooding problems in the area. 3A-4 Section 3B DESCRIPTION OF THE TWENTYMILE CREEK WATERSHED On Plate No. 8-11(l) the base map for the Twentymile Creek Watershed Area is presented. Also shown are the direct drainage watershed areas for unnamed creek nos. 19-23. These direct drainage watersheds are discussed in further detail in Volume 1. The base map reveals major topographic features of the watersheds. The Twentymile Creek Watershed is located primarily in New York State with only a small portion in North East Township. It covers an area of approximately 21,800 acres in New York and 1,000 acres in North East Township. 3.1 Local Input Data There are five types of local data which have been considered in the description of the Twentymile Creek Watershed Area. These include: 1. Signif icant obstructions 2. Existing drainage problems 3. Location of existing storm sewers 4. Proposed storm sewers 5. Existing and proposed flood control projects Each of these types of data are discussed in the following paragraphs. This information is as complete as possible at the time of writing. Additional information may be added as it becomes available. 3.1.1 Significant obstructions A significant obstruction is defined as any structure or assembly of materials which might impede, retard or change the flow of storm water runoff. Significant obstructions in the Twentymile Creek Watershed were located both by surveys conducted by the consultant and by local input from municipal and county officials as well as the Advisory Committee composed of representatives from the affected municipalities. Those obstructions which were identified are described on Table 8-9 and located on the map presented on Plate No. 8-12 Various significant obstructions were mapped. These include all bridge abutments and piers or culverts through which the main stream or side branches pass as they flow under highways, driveways and railroads. While many of these structures do not obstruct normal flow, all may be considered potentially obstructive during severe storms if debris is allowed to collect in culvert openings or around bridge piers. They also serve as potential entrapments for ice floes. Q)For the convenience of the reader and to facilitate locating of tables and maps, all of these illustrations are placed in order in Appendix A at the end of this report. 313- 1 The importance of these obstructions is obvious since anything which interferes with the natural flow of the stream can contribute to local flooding under storm conditions. The control of increased runoff due to development that would result from the implementation of this storm water management plan will insure that these structures will operate hydraulically at their present levels. Thus, if a particular structure has no recurrent problems in passing stream flows at the present time, no problems would be expected in the future under the plan as development proceeds. Flooding problems due to structures of insufficient hydraulic capacity will not get worse in the future, nor will they be eliminated by the institution of these storm water management policies. The intent of this plan is to maintain the status quo regarding stream flow. 3.1.2 Existing drainage problem areas One drainage problem was specifically identified in the Twentymile Creek Watershed. As indicated in Table 8-10 and shown on Plate No. 8-13, the problem is recurrent flooding due to the formation of ice jams at the mouth of Twentymile Creek on Lake Erie. Under emergency conditions the responsibilty to take corrective action falls first on the local municipality. It is recommended that the local municipalities in this case make advance arrangements with all involved agencies and individuals to obtain all required permits, permission to enter private property etc. in order to regularly remove the ice in the creek. If the municipalities do not have the means to handle a particular situation, they should turn first to the Erie County Emergency Management Agency. This office is presently under the direction of Mr. James Smith (telephone: (814) 454- 5811). Problems that go beyond the capabilities of this agency should be referred to the Pennsylvania Emergency Management Agency, Western Region Office in Indiana, Pennsylvania. This is presently under the direction of Mr. Carl Keuhn (telephone: (814) 357-2990). The United States Army Corps of Engineers is available for technical assistance only. It is their policy to become further involved only in the, most hazardous of cases. As other drainage problems are identified in the Twentymile Creek Watershed Area, they can be added to Table 8-10 and Plate No. 8-13. 3.1.3 Existing storm sewers The third type of local input involved the location of all existing storm sewers in the Twentymile Creek Watershed Area. At the time of writing, there were no known storm sewer systems in this area. Plate No. 8-14 is provided to locate existing storm sewers as they are identified. 3B-2 3.1.4 Proposed storm sewers Tables 8-11, 8-12 and 8-13 are provided for the purpose of listing and locating all proposed storm sewers in the Twentymile Creek Watershed Area. At the time of writing this report, no new storm sewers are known to have been proposed for the Twentymile Creek area. The tables are provided so that information can be added to them and Plate No. 8-14 as it becomes available. 3.1.5 Existing and proposed flood control projects Plate No. 8-15 and Tables 8-14 and 8-15 are provided for the purpose of entering the location and description of all existing and proposed flood control projects. At this time, there are no known flood control projects in the Twentymile Creek Watershed Area. 3.2 Present and Projected Land Use Present land use is shown on Plate No. 8-6. Existing land use data was taken from the Erie County Land Use Plan Update (June, 1978). It can be seen from the existing land use map that the area is at present largely rural with some residential areas and some small pockets of commercial usage. Projected land use was derived from various Erie County projections. This is shown on Plate No. 8-7. As can be seen, the Twentymile Creek Watershed Area is seen as an area of extremely high potential growth. This would be most evident if the proposed U.S. Steel plant is built in Springfield Township. Existing development has brought about the institution of a sewage disposal system in portions of the watershed area. The presence. of a public sewer system often has a strong influence on area growth. 3B-3 Section 4 STANDARDS AND CRITERIA FOR STORM WATER MANAGEMENT The following are the recommended standards and criteria for storm water management in the Sixteenmile and Twentymile Creek Watershed Area. A complete derivation and justification of these standards are to be found in Volume I of this study report. The recommended standards and criteria may be completely satisfied by use of the on-site approach discussed in Section 5 of this volume. The most fundamental standard of this study is that the amount of flow along Sixteenmile Creek must not be allowed to increase at the data points labeled "All through "I" on Plate No. 8-10 above those existing flows indicated on Table 8-8 for each of these points. These flows were obtained from a computer model developed expressly for Sixteenmile Creek using the design storm described below. Flows at positions between the given points must not exceed a straight line interpolation of flow values at adjacent points. This will insure that the flow characteristics of Sixteenmile Creek will remain at their 1981 level for storms equal to or less than the design storm. The objective is to maintain the existing level of flow in the main stream channel for the design storm and to maintain bank-full capacity for the side branches. A policy such as this will not only effectively manage increased runoff as desired, but will help to maintain the sensitive ecological balance of the stream. This fundamental approach of not allowing an increase in the flow of storm water also applies to Twentymile Creek even though a computer model was not developed for this stream. 4.1. Definition of Design Storm The design storm for this study has been determined to be the 10-year, 24- hour storm. The choice of this storm is justified in Volume I of this study. The 10- year, 24-hour storm is that theoretical storm of 24-hour duration that statistically will occur once in 10 years. On the average such a storm would produce 4.8 inches of rain in a 24-hour period. As previously mentioned, this is the storm.used to derive the magnitude of flow at the data points described above. 4.2 Definition of Type I and Type 2 Channels Because some of the channels that make up the Sixteenmile Creek and Twentymile Creek drainage systems are more able to carry increased flows than are others, two sets of criteria and standards have been devised for two types of channels. The first, or Type I Channels, are characterized as main stream channels. They have a well-defined flood plain and can handle increased flows very easily. These are the shaded portions of the Sixteenmile and Twentymile Creek drainage system shown on Plate No. 8-9, "The One-Hundred-Year Flood Plain." The entire Twentymile Creek Watershed Area contained in Pennsylvania is considered to discharge its runoff into Type I channels. The second are referred to as Type 2 channels. These consist of all the other portions of the Sixteenmile Creek drainage system that are not shaded on Plate No. 8-9. They are characterized as branch stream channels. Plate No. 8-10, the Subwatershed Map for Sixteenmile Creek, indicates those portions of the watershed area whose runoff is initially discharged into Type I Channels and those whose runoff is initially discharged into Type 2 Channels. 4-1 4.3 Criteria for Type I Channels (Main Stream) For those sites which are to discharge their runoff into a Type I Channel, it wiRl be required that the increased runoff after development (due to the design storm) be managed by any of the recommended on-site methods discussed in Section 5. That is to say, the runoff due to the 10-year, 24-hour storm is to be calculated again for the same storm taking into account the specific proposed development. The difference between these two runoffs is that which must be managed. 4.4 Criteria for Type 2 Channels (Branch Streams) For those sites which are to discharge their runoff into a Type 2 Channel, a more stringent standard is to be applied. This is necessary because these channels typically are too small to accommodate increased runoff. They have no flood plain to act as a cushion. In this situation, the amount of storm water that must be stored is the difference in runoff between that due to proposed land use for the 10-year, 24-hour storm and that due to the mean annual storm for existing land use conditions. As defined previously, the mean annual storm (1) is calculated by taking the largest storm for each year on record and averaging them together. Statistically, the mean annual storm is equivalent to a storm with a return frequency of 2.33 years. Whereas side branches are naturally formed to handle the more frequent mean annual storm, this more stringent criterion would now protect them against flooding for all storms up to and including the 10-year, 24-hour storm. (OThe concept of a mean annual storm was developed by L. Leopold and referenced in Storm Water Management, 1980. 4-2 Section 5 IMPLEMENTATION 5.1 Introduction Every parcel of land has unique storm water runoff characteristics which inevitably change when the parcel is developed, usually resulting in an increase in storm water runoff from the site. When development takes place the increase in storm water runoff is magnified and serious problems can result. Prior to the development of this Plan there was no established method through which a municipality could require developers to take precautions against causing storm water runoff problems. The purpose of this Plan is to help correct the situation by establishing standards for storm water management and an administrative procedure whereby those standards can be applied by local governments to development within their jurisdiction. The Storm Water Management Plan will be implemented by individual municipalities through the adoption of a storm water management ordinance or through amendments to existing subdivision or zoning regulations. Administration of the storm water management program will be accomplished through a ccmbination of enforcement actions undertaken through the building permit process and through the subdivision review process, both of which are detailed later in this Section. 5.2 Special Considerations Prior to discussing the specifics of the Building Permit Process and the Subdivision Review Process, two subjects which fall outside of the scope of this Plan's evaluation procedures will be discussed. The Building Permit and Subdivision Review evaluation procedures for storm water management apply to all forms of development and land use except development in areas with an existing storm sewer infrastructure and with respect to agricultural land. In situations where development or redevelopment occurs in an area where direct access to an established storm sewer infrastructure is possible, the development or redevelopment is considered sufficient to manage its storm water runoff if its on-site storm drainage network is incorporated into the existing storm water infrastructure. By connecting with the existing storm sewer system, the development would be relieved of further obligations to manage storm water runoff in accordance with this Plan unless the municipal governing body perceives a potential storm water drainage problem or if the governing body wishes to correct an existing storm drainage problem. in these cases where the governing body desires a more stringent application of storm water management controls they may require that a detention/retention plan be developed which would alleviate the storm water drainage problem. 5-1 Evaluating agricultural land for compliance with storm water management controls is the second topic which falls outside of the scope of the Building Permit and Subdivision Review procedures. With respect to agricultural land, the recommended method of storm water management is to have a Soil Erosion and Sedimentation Control plan and/or permit prepared in accordance with existing State law and reviewed by the Erie County Soil Conservation Service. This applies only to cultivated land; agricultural accessory structures and residential structures should be evaluated by the municipality through the applicable method as outlined in the following sections. 5.3 Building Permit Process If a proposed subdivision is defined by the host municipality's subdivision regulations as a minor subdivision (usually 10 lots or less) or if development is proposed involving no subdivision of property, then storm water management standards and criteria should be evaluated at the time when development is formally proposed via an application for a building permit. This system is designed so that smaller developments may occur without incurring added engineering expense and so that municipalities can implement storm water management requirements without incurring substantial administrative overhead expense. The recommended technique to be followed when evaluating a minor subdivision or a development on an existing lot of record is presented here. First, all developments which fall' into the above categories must meet each of the following: Standard Controls 1. Roof drains are not to be connected to streets, sanitary sewers or roadside ditches. 2. Runoff from the impervious areas must be drained to the pervious areas of the property. 3. Runoff is not to be collected or concentrated into an artificial conveyance and discharged onto adjacent property. Next, the zoning officer must calculate the percentage of the parcel which will be covered by impervious surfaces after development is concluded. In this context impervious surfaces mean all land covered by a house, barn, garage, patio, driveway, etc. Information needed to calculate the percentage of impervious area should be readily available on the building permit application. Once the calculation is made the zoning officer should refer to the following table to determine how many storm water controls in addition to those listed above will be needed to comply with the standards of the Storm Water Management Plan. The additional controls can be found in Table 8-16. 5-2 Determination of Controls Less than 15% impervious Standard controls only 15% - 19.99% impervious Standard controls only plus one additional control 20% - 24.99% impervious Standard controls plus 2 additional controls 25% - 30% impervious Standard controls plus 3 additional controls The methodology outlined above is designed to be used for a proposed development which covers 30% or less of the parcel with an impervious surface. Under such circumstances the zoning officer can show the potential developer what storm water management controls are needed in order to receive this building permit. If the proposed development will cover greater than 30% of the parcel with an impervious surface or if the total impervious area exceeds one acre, then a licensed professional must be consulted to prepare a detention/retention plan which meets the approval of the governing body. An additional fee is recommended to be added to the existing building permit fee to cover the expense of administering the program. 5.4 Subdivision Review Process If a development is defined by the host municipality's subdivision regulations as a major subdivision (usually more than 10 lots), the storm water management standards and criteria should be evaluated during the subdivision review process. This use of the subdivision review process is designed to ensure that large scale developments employ proper techniques to control storm water runoff and that these controls are firmly established prior to municipal or county approval of the subdivision plat. When a preliminary major subdivision plan is submitted for municipal review it shall be accompanied by detailed storm water detention/ retention specifications which meet the criteria of the Plan and which have been prepared by a professional licensed to perform such work in this Commonwealth. The proposed storm water detention/retention specifications shall be reviewed by the municipality and/or its engineer and shall satisfy the municipality before the major subdivision plan is approved. The municipality may require controls which are more stringent than those which meet the Storm Water Plan's criteria if circumstances dictate that such measures are needed to alleviate a current drainage problem or a suspected future drainage problem. 5.5 Conclusion The Lake Erie and Elk Creek Storm Water Management Plan has been developed in accordance with Act 167 of 1978, the Pennsylvania Storm Water Management Act. Under the provisions of this Act, municipalities are granted certain powers and must assume certain responsibilities. One of the responsibilities which has been assigned to local governments by the Act is the responsibility to adopt implementing ordinances such as those described in this section. Another responsibility assigned to the municipality is that of properly enforcing the storm water management ordinances and regulations. Because of the responsibilities awarded to municipalities under Act 167, each municipality affected by this Plan should consult their municipal solicitor for a briefing about the extent of their obligations under the provisions of Act 167. 5-3 Section 6 THE SIXTEENMELE CREEK COMPUTER MODEL As has been discussed previously, a computer model of the Sixteenmile Creek drainage system was developed f or the purpose of this study. A complete description of the background and development of this computer model is given in Volume 1 of this report. The following is a summary of the data used as input for the model and a description of the data it yielded as output. 6.1 Existing Stream Characteristics The existing land use for the Sixteenmile Creek Watershed Area is shown on Plate No. 8-6. This is a base land use against which future development is to be compared upon adoption of this storm water management plan. It can be seen that the area is generally rural with some residential, commercial and industrial development. The runoff due to this land use was entered into the computer model. A soil factor derived from the various types of soils found in the Sixteenmile Creek Watershed Area, as shown on Plate No. 8-8, was also taken into account. The results of the computer output are summarized on Table 8-8. The flow characteristics of Sixteenmile Creek due to the runoff from existing land use are shown in the first columns labeled "Existing Runoff" for various data points. These data points are located on Plate No. 8-10. These are the flow characteristics of the stream which must not be altered due to the development of land in the watershed area. 6.2 Post-Development Stream Characteristics A projected ultimate land use for the Sixteenmile Creek Watershed Area was taken from the Erie County Land Use Plan Update (June, 1978). It is shown on Plate No. 8-7. This projection assumed that all of Erie County would develop to its maxmum potential, as it would if U.S. Steel were to build the large steel producing facility it has proposed for Springfield Township. Although it is, at present, primarily a rural area, projections indicate moderate growth in residential and industrial usage. The runoff due to this projected land use was entered into the computer model. Again, a soil factor was taken into account. The resultant flow characteristics at the data points are shown in the column labeled "Ultimate Runoff" in Table 8-8. It can be seen that the peak flow of the ultimate runoff is considerably higher at all points than is that of the existing runoff. For example, at the outlet to Lake Erie, the peak flow is calculated to be 8,327 cubic feet per second (cfs) for existing runoff and 6,820 cfs for ultimate runoff. 6-1 The depth of the ultimate flow is substantially higher at all data points. The increased depth becomes more critical in upstream reaches of the watershed. This implies a great risk of flooding in portions of the channel which have a naturally smaller cross section. These are generally the branch or Type 2 Channels. The velocity of the flow can also be seen to be much higher for ultimate runoff than for existing runoff. This is an undesirable situation that could result in excessive erosion of the stream bed. The stream channels would eventually widen and deepen beyond their present limits and possibly interfere with development along their banks. Foundations for bridges, culverts or retaining walls might be undermined due to a process known as scour. Scour is the washing away of earth around the footings of piers, bridge abutments retaining walls or the like, and in the process, exposing them. This reduces their structural stability. Water quality would decline due to the inordinant amount of soil particles being carried along by the current. Development would decrease the absorption of rainfall due to the amount of impervious cover it would probably bring with it. This could lower the groundwater table to unacceptable levels. The COWAMP Study Area 7 Report, prepared by the Department of Environmental Resources of the Commonwealth of Pennsylvania does not reveal any of the above to be current problems for the Sixmile Creek Watershed Area. This makes it very important to maintain existing water quality standards related to storm water runoff. In addition, the Clean Streams Law of Pennsylvania regulates activities that affect any stream in the Commonwealth in order to preserve and improve the purity of their water. The Storm Water Management Act will aid in the attainment of these objectives. All work done to manage storm water must be done in compliance with these rules and regulations. 6-2 APPENDIX A TABLES AND PLATES PLAN NO SIGNI,FICANT OBSTRUCTIONS VRAINAGE AREA NO. MUNICI PALITY TYPE Of STRUCTURE SQ. mrs. CAPACITY( C.F.S.) DATE BUILT OWNER AND ADDRESS f M., Jbest 9 _ - J - M-meas" 73-jh'@o -@: 4 IV., lh-1 7.-b@, 0emv?11yovM7 i2e -,e@ @a@z- ool 7r .5 N-m,a@/ Twjh,;o 11 7@ @A 6 IV-lh-t 7b-&, C.1va'o 7 IV.11171@Sl 7b-zh,;@ a - M-1hea- I 9 /0 W""e-vo.& I/ Alb-lheavi -j@oro A-h C,1-4 46@,ff S11-i cf-1.4 CAM- Al.. a /Z AI-11,ea4 / 7-w-,7h,,- -P 7-k4-l.'-lw? /15 Al- eas/ 7ow@sh@, 'B'A21ge All 7, -Jhll. ll'i&q@ ;'07@@shj@@ 15 lvb-lhe@" 7-,ibio c/q, ' V, .5 C@-/' I J"'el A; A-b, lh,-i 7.-,sh,,p '// C.40- 'Ile 17 mltbe.st 7.w,.sh,p /,We-, 0/' 19 mo-lheos@ 75w@jh"o &'A@glo zo N.,me';7T A@; SWM 25:32 WOODRUFF, INC. SIXTUNMILE CREEK 'TABLE 6-1 P1 AN NO STORM DRAINAGE PROBLEMS NO. LOCATION MONWIPALITV PROBLEM PROPOSED SOLUTION Al- 1hpa,71 ;@Wlmhw el7mZo C@eew#t&-arhj 47e@Cll@PX A@Ylkla'I@IS 1,4 X L clh-l 0, Mor CV 6x- "a"w clulk, 141@-a, oh"', I WOODIRUFF@, =!JN!C. SWIWI 211:32 I.... SIX*MENMILE CRIEfK TABLE 11-2 PLAN NQ- PROPOSED STORM WATER COLLECTION SYSTEMS FINAL OWNERS"If SYSTEM CAfACITY AND NO@ LOCATIOhl AND MUNICIPALITY [AT] MATED COST ars. 4lilb MAINTENANCE RESPONSIBILITY MAP I 1TEM REL&&QLLZkWu.. -------- WOODRUFF, SWM 25:32 SIXTEENMILE CREEL TABLE t-3 PLAN NO. STORM WATER COLLECTION AND CONTROL FACILITIES PROjECT NO. LOCATION --JaE Of VACILITf METHODS OF FINANCING I ALL PHASES I FINANCIAL LIABILITY 2JJ2 ...... ........ La WOODRUFF, IN -Ml CREE TABLE SHEET 2 OF 2 p NO. PROJ E Crr D EVE LOPME NT'AN D'CONSTRU'CTIO N SCHEDULE AND COSTS SCHEDULE ESTIMA ED COSTi' CONSTJ JCTInN MAINTENANCE PROILCT NO DESIGN RIGHT-OF-WAY RIDDING nESIGN RIGHT-OF-WAY CONSTRUCTION tANNUALI WOODRUFF. INC] NWIMI L"E" IC I I E 2 K TABLE 8.5 EXISTING FLOOD CONTROL PROJECTS P-,))F('T LOCAIION AN QATI BUILT QjkNER "-oh. A/- 7k- d'@ V-OA..S@ mb'olh@o a@'. '@; "heosy, WOODRUFF, INC.] swu 2532 SirmpmulLs CBBU TABLE LAN NQ PROPOSED FLOOD CONTROL PROJECTS NO PROJECT LOCATION AND MUNICIPALITY FTinN DATE BUILDER FINAL n.ULR CAPACITY IC FS) WOODRUFF, I C.1 swm 2332 SIXTEEN11AILE CREEIL TABLE 8-7 WATERSHED RUNOFF DATA EXISTING RUNOFF ULTIMATE RUNOFF ULTIMATE RUNOFF. WITH STORAGE LOCATION PEAK FLOW TIME OF VOLUMN IIIII.- P649 FLOVI TIM or OLUME MIL. ?FAX FLOW TIME OF VOLUME MIL. C.Fil PEAK HR. DEPTH FT. VELOCITY CU, M FRA: i4a. PFFT" FT. VELOCITY F.F4, V CU. FT. C.F.S. PEAK HR. DEPT14 FT.. VELOCITY F.P.S. cu. FT. A Ze -151 1-4-33 Z. 78 1516 6ranch 9.9 17 llf5 72 4551 zz 99 -3-52 &20 . gose S.7, 3 7z /6z e -151-h ZO?7 74 Z47f 74 tksilll --l- 1729 /00 md9 9.7 -00-1 @11- .3462 73 26a &4d *64 7z Azi -i2 I -/ Q. 6f-@h 445 509 71 74 f8dy 74 74 6. 4d 602 5210 20 5-0 Af. 5-9 --?z /053 7 f 1-- 4433 74 74 503 74 71 6155 211 657 13,45 lZd4 75 /508 2 3 - Z--d ei?5 74 6416 74 /2. 70 7665 -583 1147 It 73 Aof 63d@ - ---j 61315 ?4 .541 11.65 6.00 df 7. 72 _5.'19 /300 7z 552 la a/ f260 _/O 0 4.6e ly.43 1504 -919- 5.0@1 //.,gz L oke C620 76 1 76 A d9 5210 SWM 25:32 SIXTEENMILE CREEK TABLE 14 PLAN NO- SIGNIFICANT OBSTRUCTIONS DRAINAL ARIA No ML \11 11-Allil JNPL M Silitt It III I @PAI 11) 1 s P@ It HL ILI %\P N1111M.'s f_ -Af i5q' lv-theo@,' 75-17 h@,- J WOODRUFF, TC swm 251.41 TWENTYMILE CREEK TAPLE 8-0 -STORM DRAINAGE PROBLEMS No. IOCATIO@ TV m PRO E Noth E=t bm A@_ the 1*0 !!!E I 1@ Ll ids mid C'm -d r. Yt7l WOODRUFF, INCT. . ........ CREEK TABLE 8-10 PI Abi Nn PROPOSED STORM WATER COLLECTION SYSTEMS IVSILM CArACITY FINALOWNERSHM AND NO. LOCATION AND MUNICIPALITY CONSTR. DATE EsTim TFD COST Us. I FREQ MAINTENANCE RESPONSIBILrFY AP MAP WOODRUF INC. swM 25,41 Twr :NTYMILE :ItEEK TABLE "I SHEET I -PLAN Nd STORM WATER COLLECTION AND CONTROL FACILITIES PROIL( I NO LOCATION TYPEOFFACILITY P4fTHODS OF FINANCING I ALL PflASES I FINAN( tAt LIABILITY N eni, WOODRUFF, swm,5;41 TwEKINMILE CREEX TABLE 1-12 SHEET 2 Of 0. PROJECT'DEVELOPMENT AND CONSTRUCTION SCHEDULE AND COSTS SCHEDULE ESTIMA ED COSTS 0 MAINH@NANCE PROJECI NO MSIGN RIGHI-OF-WAY BIDDING 'TART FINI-M DESIGN RIGHT-OF-WAY APOINISTRATION CQNSTRUCTION (ANNUAl I =@=_-!W 0 0 U F C. SWM 25;41 TWENTYMILE CREEK TABLE s43 EXISTING FLOOD CONTROL PROJECTS NO. -nIFCT LOCATION 6NU MWNjQgALaY DATE BUILT BUIL"a PR WM UNNEI C.PICITV N X N 4, 7- WOODRUFF, I $Wu 251.41 ...... ... @cl TWENTYMMIll CREEK TABLE 8-14 PLAN N Q PROPOSED FLOOD CONTROL PROJECTS NO PROJECT LOCATION AND MUNKI M ITY COMPLETION DATE BUILD Ng FINAL CAPACITY C F.Sw LIFE F%Pg"ANrY YR5 Ic BLIE 9-15 Table 8-16 VARIOUS ON-SITE STORM WATER CONTROL METHODS AREA REDUCING RUNOFF DELAYING RUNOFF Large Flat Roof 1. Cistern storage 1. Ponding on roof by 2. Rooftop gardens constricted 3. Pool storage or fountain downspouts storage 2. Increasing roof roughness a. Rippled roof b. Gravelled roof Parking Lots 1. Porous pavement 1. Grassy str ips on a. Gravel parking lots parking lots b. Porous or punctured 2. Grassed waterways asphalt draining parking lot 2. Concrete vaults and 3. Ponding and cisterns beneath parking detention measures lots in high value areas for impervious areas 3. Vegetated ponding areas a. Rippled pavement around parking lots b. Depressions 4. Graveltrenches c. Basins Residential 1. Cisterns for individual 1. Reservoir of homes or groups of homes detention basin 2. Gravel driveways (porous) 2. Planting a high 3. Contoured landscape delaying grass (high 4. Ground-water recharge roughness) a. Perforated pipe 3. Gravel driveways b. Gravel (sand) 4. Grassy gutters or c. Trench channels d. Porous pipe 5. Increased length of e. Dry wells travel of runof f by 5. Vegetated depressions means of gutters, diversions, etc. General 1. Gravel alleys 1. Gravel alleys 2. Porous sidewalks 3. Mulched planters Source: Urban Hydrology for Small Watersheds. Technical Release No. 55 Table 8-17 ADVANTAGES AND DISADVANTAGES OF VARIOUS ON-SITE STORM WATER CONTROL METHODS MEASURE ADVANTAGES DISADVANTAGES A. Cisterns and 1. Water may be used for: 1. Expensive to install Covered Ponds a. Fire Protection 2. Cost required may b. Watering lawns be restrictive if the c. Industrial processes cistern must accept d. Cooling purposes water from large 2. Reduce runoff while only drainage areas occupying small area 3. Requires slight 3. Land or space above maintenance cistern may be used for 4. Restricted access other purposes 5. Reduces available space in basements for other uses B. Rooftop 1. Esthetically pleasing 1. Higher structural Gardens 2. Runoff reduction loadings on roof and 3. Reduce noise levels building 4. Wildlife enhancement 2. Expensive to install and maintain C. Surface Pond 1. Controls large drainage 1. Requires large areas Storage (usually areas with low release 2. Possible pollution residential 2. Esthetically pleasing from storm water areas) 3. Possible recreation and siltation benef its 3. Possible mosquito a. Boating breeding areas b. Ice skating 4. May have adverse c. Fishing algal blooms as a d. Swimming result of 4. Aquatic life habitat eutrophication 5. Increases land value of 5. Possible drowning adjoining property 6. Maintenance problems Table 8-17 (Continued) D. Ponding on 1. Runoff delay 1. Higher structural Roof by 2. Cooling ef f ect loadings Constricted f or building 2. Clogging of con- Downspouts a. Water on roof stricted inlet re- b. Circulation through quiring maintenance 3. Roof ponding provides f ire 3. Freezing during protection for building winter (expansion) (roof water may be trapped 4. Waves and wave in case of fire) loading 5. Leakage of roof water into building (water damage) E. Increased Roof 1. Runoff delay and some 1. Somewhat higher Roughness reduction (detention in structural loadings a. Rippled roof ripples or gravel) b. Gravel on roof F. Porous 1. Runoff reduction (a and b) 1. Clogging of holes or pavement 2. Potential groundwater gravel pores (a and (parking lots recharge-(a and b) b) and alleys) 3. Gravel pavements may be 2. Compaction of a. Gravel cheaper than asphalt or earth below parking lot concrete (a) pavement or gravel b. Holes in decreases impervious permeability of soil pavements (Y4 (a and b) in. diam.) 3. Ground-water filled with pollution from salt sand in winter (a and b) 4. Frost heaving for impervious pavement with holes M 5. Difficult to maintain 6. Grass or weeds could grow in porous pavement (a and b) G. Grassed 1. Runof f delay I . Sacrif ice some land channels and 2. Some runoff reduction area for vegetated vegetated (inf i1tration recharge strips strips 3. Esthetically pleasing 2. Grassed areas must a. Flowers be mowed or cut b. Trees periodically (maintenance costs) Table 8-17(Continued) H. Ponding and 1. Runoff delay (a, b, and c) 1. Somewhat detention 2. Runoff reduction (a and b) restricted measures on movement of impervious vehicle (a) pavement 2. Interferes with a. Rippled normal use (a and c) pavement 3. Damage to rippled b. Basins pavement during c. Constructed snow removal (a) inlets 4. Depressions collect dirt and debris (a, b, and c) 1. Reservoir or I. Runoff delay 1. Considerable detention basin 2. Recreation benefits amount of land is a. Ice Skating necessary b. Baseball, football, etc. 2. Maintenance costs if land is provided a. Mowing grass 3. Esthetically pleasing b. Herbicides 4. Could control large c. Cleaning drainage areas with low periodically (silt release removal) 3. Mosquito breeding area 4. Siltation in basin J. Converted I. Low installation costs I. Requires periodic septic tank for 2. Runoff reduction maintenance (silt storage and (infiltration and storage) removal) ground-water 3. Water may be used for: 2. Possible health recharge a. Fire protection hazard b. Watering lawns and 3. Sometimes requires gardens a pump for c. Ground-water recharge emptying after storm 1. Runoff reduction I. Clogging of pores or Ground-water recharge (inf iltration) perforated pipe a. Perforated 2. Ground-water recharge 2. Initial expense of pipe or hose with relatively clean water installation b. French drain 3. May supply water to (materials) c. Porous pipe garden or dry areas d. Dry well 4. Little evaporation loss L. High delay 1. Runoff delay I. Possible erosion or grass (high 2. Increased inf iltration scour roughness) 2. Standing water on lawn in depressions Source: Urban Hydrology for Small Watershed Technical Release No. 55 L Qn, 4 N1 IV NO A& GREENFIELD RT 0.@@ Al N 14 T- NEW YOR 2000 a 2000 4000 0 FEET w OODRUFF, INC. "s 12 ly RIH E..'s BoRo '@iLDEHILL RD. 0 14 4 k c E RD. 2 3 DAM Itt 19 GREENFIELD RTH EA 20 PE N YLVANI A NEW YO WOODRUFF, INC. .......... . BCAU 0 MET 4 $Q NORT11 AS ORO si % GREENFIELD Q NORTH EAST ouLF PENNSYLVANJA NEW YORK a 2am 4m am Mw WOODRUFF, INC. ........ wALl w nsir RAP Z"AISMnNO SEWER 0 EAS GREENF p NEW YORK WOODRUFF, INC. ......I... ......... oc" 0 posr @71 NOR114 AS ORO 3 GREENFIELD NORTH EAST EXISI raolm PENNSYLVANI.A NEW YO.K WOODRUFF, INC. WALS M F99T .... . . . . wElaNnto cAr. SUSWAMRSMw FVR &rZTMW LANO USE 7464 3 74.41 4 75." 5 75/5 C, 6 75.87 7 7d/? GREENFIELD@'."-.' fdff NORTH EAST ff 48 2 12 77.21 6d. 68 "i" 00 14 65.16 /5 00 /6 7609 ir EXISTING LAND USE LEGE? OPEN 3 WOODED PENNSYLVANIA CULTIVAM NEW YORK RESMENTIA COMMEACI". __INDUSTRIAl SwM 2s:Jl "m 4m "M SIXTEENMILE CREEK WATERSI, WOODRUFF, IN ....AMA EXISTING LAND USE .... WALA M PUT .................... ........... ................ ............. WEIGHrEp alf WRIVArERSNED FOR 4VW7FLAV 14F .... ........ NUMBER 2 7155 . ............ 70." 79.67 5 7S. Zd GREENFIELD a IF 7904 NORTH EAST 7 77.74 ---i2 -39 61401 74. ze d/. za vi ID 41 74.iF.9 aa 60 78.04 7,1.35 17 18 7y. ed I 2 PENNSYLVANIA ULTIMATE LAND USE LEGEND NEW YORK RESIDENTIAL --AGRICULTUR WOODED RESIDENTIAL COMMERCIA. L INDUSTRIAL SWM 25:32 2000 0 20M 40m 4000 mm SIXTEENMILE CREEK WATERS11 WOODRUFF, INC. - I ULTIMATE LAND USE .... . ........ SCALE FIECT . . . . . . .... ............ 5p ............ GREENFIELD NORTH EAST .......... PENNSYLVANIA NEW YORK 3ail Akax6@ 5 SoilAtumbor 6 Joil Alumber 9 20" a 2m 40w 600 am w OODRUFF, INC. A NORTH A ORO ItI GREENFIELP NORTH EAST PENNSYLVANIA NEW YORK rAlF AMO- MAR A40M PLAN AS ACRIVED D 2ow rAIr ACATIOM" FLOW 4V&WAAFC9 PAOM" WOODRUFF, I WC ensigaMMM OCALA PIET 10 17 -irz) H EAS 11\0 AWr, THE SYMBOL BELOW tS USED 'M LOCATE THE DATA FORT$ UMG ON THE.WATEROM NOWF DATA CHART (TAKE 0 -4. r/me SL18WATERSNED AREA OF caVCENTRArlo# wmarR ACRES Amures li/ 99700 47d9 4 @2r 166979 68.97 3 154.58 Z3. zs GREENFIELD 4 4ZI60 Z6.21 NORTH EAST -5 145155 ez. 00 6 94Z47 sz.63 -7 783Z9 55 ZZ P 3OC199 32/0 19 34.Zd 31.66 z /0 771.36 4JG7 IZJJ7 Z/. zz 1083419 46.05 fs t9866 50. Z7 14 14rx93 27.05 15 15dd4r6 69.94 /6 335.79 32-53 PENNSYLVANI@ /7 238. At ZJq 39 NEW YORK r8-- 812.;101 6-1. 24 rOrAL WArERSHED AREA /# ACRES 12,402.30 A4WrhArAUWAV7VrHVf0"MV&LJ + 25:32 2000 0 20" 4m 4000 am SIXTEEN MtL:WCMREEK WATERS11 WOODRUFF, INC. e!5;Q!!T!!rmm- W"LE 0 FEET SUBWATERSHED MAP NORTH 0 .1co FAAICH Ur" 2000 0 2000 4000 60M Sam WOODRUFF, INC. SCALE M FEET /-@@NORTH No'tpotk ZV i 4 3 14. + 0 jAAyCH LINE ag" a 2m 4000 6000 nm WOODRUFF, INC. -* WALE 0 ff9T NORTH MATCH LINE 2000 0 2000 4000 60M 0000 WOODRUFF, INC. FEET NORTH MAT LINE 200 a 3ow 4000 6000 sm WOODRUFF, INC, - ..... ........ SCOAA A FZffT AW. NORTH E t fmAAjcH E WOODRUFF INC. 2000 0 2M 4000 ww 6000 FECT APPENDIX B Calculations To Determine Increased Runoff And Examples Of Specific On-Site Storage APPENDIX B CALCULATIONS TO DETERMINE INCREASED RUNOFF AND EXAMPLES OF SPECIFIC ON-SITE STORAGE The procedures presented in this appendix are applicable to all unit developments which contain between 2500 square feet and 43,560 square feet of impervious surface area. Those exempt cases discussed in the text need not make the following calculations. Developments with more than 43,560 square feet of impervious surface area must consult a qualified professional person to aid in determining their excess storm water runoff volume. By following these methods, the non-technical individual can easily determine the amount of excess storm water runoff which he is required to manage. The ethods of control presented in this study, or any other approved innovative methods, may be used to manage this calculated runoff volume. m Excess Storm Water Runoff Calculation Procedure Step I Determine dimensions of proposed buildings, drives, patios or other impervious areas. These can usually be found on building site plans. Step 2 Calculate impervious area. The more common shapes that will be encountered are rectangles, triangles or circles. Equations to calculate the areas of these shapes are as follows: (all dimensions are assumed to be in f eet) 0 Rectangle: area (sq. ft.) = length (ft.) x width (ft.) ii) Triangle: area (sq. ft.) = 1/2 x base (ft.) x height (ft.) iii) Circle: area (sq. ft.) = 0.785 x diameter2 (ft.) Step 3 Refer to Section 4.2 and plate of volume describing the watershed in which construction is to take place. If construction is found to be along a Type 1 channel, then use Type I criteria. All others use Type 2 criteria. Step 4 Use Figure B-1 to find excess runoff volume to be managed. Example: Figure B-2 shows a typical site plan for proposed residential lot located along a Type I Channel. Determine the amount of excess runoff volume required to be managed. (1) Dimensions as shown on Figure B-2. B-1 (2) Impervious Area: (a) Drive: 141 x 701 = 980 sq. ft. (b) House: 401 x 801 = 3200 sq. ft. (c) Patio: 1/21 x 201 x 201 = 400 sq. f t. Total Impervious Area 6180 sq. ft. (3.) Type I criteria as given. (4.) From Figure B-1, excess runoff volume to be managed is 1150 cubic feet. Note: One acre contains 43,560 sq. ft. One cubic foot contains 7.48 gallons of water. B-2 FIGURE B -1 Mcltss RUNOFF VOL FROM IMPEWYOUSA zo 14 - - - - - - 12 "rype r IMAFRVIM@ AEA /0 VOZZIAfF@F73)=(225,rIAWAFQIIIOW ARE4 EXA llf,06F ;-o 1WERIII&AS ARV 6 40 f - --- 7 7- 4 IT 0 a r 1-U EXC-CS-SRUAIO.Cir /0-/Z/M-c X/000 /7')'j FIGURE B-2 TYPICAL RESIDENTIAL SITE PLAN 40' Q0 House 80, R1W RIW /00, FIGURE B- 3 ON-SITE STORM WATER MANAGEMENT ALTERNATE NO. I SURFACE STORAGE A 75 4r&o 4 c7ec -tion A -A 400 zo;q)wo Hou-se 60' RIW Rlw /0,04 FIGURE B-4 ON-SITE STORM WATER MANAGEMENT ALTERNATE NO.2 OVERSIZED STORM SEWER PIPE 410 Houce 80' 54" L?74OrM wer Ape Rlw /004 Rlw FIGURE B-5 ON-SITE STORM WATER MANAGEMENT ALTERNATE NO.3 POND STORAGE 241 24 1 40' Houce 30' t Rlw Rlw /00, FIGURE B-6 ON-SITE STORM WATER MANAGEMENT ALTERNATE NO. 4 UNDERGROUND TANK STORAGE lo'L Z House 80' IN Rlw /00, RIW .1 3 6668 14109 4575