shamona creek, pennsylvania watershed study and improvement recommendations, 2013. by gannett...

Shamona Creek Watershed Plan

December 31, 2012

Prepared for: Prepared by:

Uwchlan Township Gannett Fleming, Inc. 715 N. Ship Road Exton, PA E. B. Walsh & Associates, Inc.

Funding Provided by: Pennsylvania Department of Environmental Protection Growing Greener Program

Shamona Creek Watershed Uwchlan Township

Chester County, PA

Acknowledgments Shamona Creek Watershed Plan has been financed by a Growing Greener Grant provided by the Pennsylvania Department of Environmental Protection. The views expressed herein are those of the author(s) and do not necessarily reflect the views of the Department of Environmental Protection. This Watershed Plan has been prepared for Uwchlan Township by:

Edward B. Walsh & Associates, Inc. Lionville Professional Center 125 Dowlin Forge Road Exton, Pennsylvania 19341

and

Gannett Fleming, Inc. Valley Forge Corporate Center 1010 Adams Avenue, Audubon, PA 19403-2402

Special thanks to the Uwchlan Township Board of Supervisors for their support of this project.

Frederick W. Gaines Joseph E. Toner III Milton H. Bozarth

Also, special thanks to the Brandywine Valley Association for the assistance with the Assessment Report for Shamona Creek and East Branch Brandywine Creek Watersheds Chester County, Pennsylvania dated April 2010 and; Restoration Plan for Shamona Creek and East Branch Brandywine Creek Chester County, Pennsylvania dated May 2010.

Shamona Creek Watershed Plan Page 2

Table of Contents 1 Introduction .................................................................................................................. 5

2 Watershed Information ................................................................................................ 6

2.1 Watershed Description .......................................................................................... 6

2.2 Watershed Classifications...................................................................................... 7

2.3 Existing Land Use .................................................................................................. 8

2.4 Land Cover ............................................................................................................. 9

2.5 Rainfall Data .......................................................................................................... 9

2.6 Floodplain ............................................................................................................ 13

3 Existing Conditions Inventory .................................................................................... 17

3.1 Stream Encroachments ........................................................................................ 17

3.2 Sanitary Sewage Treatment Facilities ................................................................. 20

3.3 Stormwater Management Facilities .................................................................... 21

4 Watershed Studies ...................................................................................................... 22

4.1 Assessment Report for Shamona Creek Watersheds .......................................... 22

4.2 Restoration Plan for Shamona Creek .................................................................. 24

5 Municipal Regulations ............................................................................................... 26

5.1 Township Stormwater Management Ordinance. ................................................ 26

5.2 Township Comprehensive Plan ........................................................................... 26

5.3 Township Zoning Ordinance ............................................................................... 27

5.4 Township MS4 Permit ......................................................................................... 28

6 Watershed Improvement Goals and Issues ............................................................... 29

6.1 Cause of Impairments Discussion ....................................................................... 30

6.2 Urbanization of the Watershed Discussion ......................................................... 31

6.3 Identification of Pollution Sources ...................................................................... 32

6.3.1 Point Source Pollution .................................................................................. 33

6.3.2 Non-Point Source Pollution .......................................................................... 33

7 Watershed Improvement Recommendations ............................................................ 36

7.1 Land Use Planning ............................................................................................... 36

7.2 Stormwater Management Planning .................................................................... 38

7.3 Public Education and Outreach ........................................................................... 39


7.4 Watershed Improvement Projects....................................................................... 41

7.4.1 Streambank Stabilization Projects ............................................................... 41

A. Shamona Creek Main Stem. (Parcel 33-3-89 Greenbriar Open Space) ..... 44

B. Eagleview Corporate Center (Eagleview Lots 59 and 60) ............................ 47

C. Shamona Creek Park ........................................................................................ 49

D. Martin Memorial Park .................................................................................. 49

E. Stream encroachments ................................................................................. 51

(1) Encroachment #4 Kingston Lane. ......................................................... 51

(2) Encroachment #3 Shamona Creek Park ................................................ 52

(3) Encroachment #2 Crooked Bridge ........................................................ 52

7.4.2 Land Use / Land Cover Improvement Projects ............................................ 53

A. Happy Days Farm Parcel 33-4-28.1, 28, 27.1, 29 ...................................... 53

B. Township Park Land. Shamona Creek Park & Martin Memorial Park. ...... 54

C. Ponds ................................................................................................................ 54

7.4.3 Watershed Improvement Projects ................................................................ 56

A. Sheree Boulevard / Route 100 Pottstown Pike Ramp .............................. 58

B. Pennsylvania Turnpike / Route 100 Pottstown Pike Interchange ........... 61

C. Wharton Boulevard Dam ................................................................................. 63

D. Various Detention Basins. ............................................................................ 66

(1) Eagleview Corporate Center - Pennsylvania Avenue ................................ 66

(2) Eagleview Corporate Center Eagleview Boulevard Dam ....................... 66

(3) Development basins ................................................................................... 71

(a). Martin Memorial Park (Seasons Development) ..................................... 71

(b). Ridings Subdivision ................................................................................ 71

(c). Shamona Creek Park - Brookwood Subdivision Open Space ................ 72

(d). 390 Eagleview Boulevard - Journal Register East, Inc. ........................ 73

(e). The Shops on Eagleview Boulevard - LTK Associates, Inc. ................... 73

(f). Calvary Chapel 215 Dowlin Forge Road ............................................. 74

(g). Windham Subdivision - Dowlin Forge Road / Samuel Drive ............... 75

E. New Stormwater Management Facilities. .................................................... 75

8 Conclusion .................................................................................................................. 76


1 Introduction

Shamona Creek Watershed is a 4.02 square mile watershed located in central Chester County, Pennsylvania. Extensive urbanization of the watershed has occurred from the 1960s to the present day. As part of the urbanization, much of the native vegetation and topsoil has been replaced with impervious surfaces altering the natural hydrologic system. While this development has been completed in accordance with the applicable state, county and local regulations of the time, the majority was completed prior to the stormwater volume and water quality regulations and some prior to peak rate control requirements that exist today. The primary objective of this Watershed Plan is to develop a strategy for the shareholders of the watershed to utilize to improve the water quality and natural hydrologic regime of the Shamona Creek Watershed. This Plan details the condition of the existing watershed and makes land use, regulatory and construction improvement recommendations that can be implemented to achieve the objective of the Watershed Plan. A local watershed group, Brandywine Valley Association (BVA), has prepared the following two recent documents for the watershed:

Assessment Report for Shamona Creek and East Branch Brandywine Creek Watersheds Chester County, Pennsylvania April 2010 and;

Restoration Plan for Shamona Creek and East Branch Brandywine Creek Chester County, Pennsylvania May 2010.

These two reports are part of their Red Streams Blue program which has been developed to focus on improving the water quality of impaired stream sections. The above referenced reports were completed independently of this Watershed Plan and are a valuable resource for information related to the Shamona Creek Watershed.


2 Watershed Information

2.1 Watershed Description

The Shamona Creek Watershed is a 4.02-square mile watershed located mostly within Uwchlan Township (3.93-square miles) with a small portion of land located within Upper Uwchlan Township (0.09-square miles). Uwchlan Township is 10.4 square miles in area and is located in central Chester County. According to the 2010 census, the population of the Township is 18,088 people.

The 4.02-square mile watershed has a mix of land uses and the majority of the land has been developed. The upper portion of the watershed has relatively modest slopes while the lower portion has more significant grade changes and existing steep slopes. The stream channels in the upper portion of the watershed have modest stream banks while the channels in the lower portion of the watershed have severely sloped stream banks. Within the watershed, there are three (3) main stream segments and multiple minor tributaries. The three (3) main segments, as depicted on Exhibit 2.0 Overall Watershed Plan, are:

Shamona Creek main stem: 3.87 miles Unnamed Tributary to Shamona Creek #1: 0.83 miles (converge with main

stem by Wharton Boulevard in Eagleview) Unnamed Tributary to Shamona Creek #2: 1.83 miles (converge with main

stem at Shamona Creek Park) The headwaters of Shamona Creek main stem originate near the PA 100 (Pottstown Pike) interchange of the Pennsylvania Turnpike and flows in a southwesterly direction toward the East Branch of the Brandywine Creek at the far western edge of the Township. The upper portion of the main stem is classified as a first order stream. The lower portion of the stream, below the confluence with the Unnamed Tributary #1 is classified as a second order stream. The Unnamed Tributary to Shamona Creek #1 originates at Dowlin Forge Road, just west of the intersection of Eagleview Boulevard, and converges with the main stem upstream of the Wharton Boulevard Dam within the Eagleview development. This unnamed tributary is classified as a first order stream.



The Unnamed Tributary to Shamona Creek #2 originates upstream from the Seasons residential development and converges with the main stem within Shamona Creek Park. This unnamed tributary is classified as a first order stream.

2.2 Watershed Classifications

The US Environmental Protection Agency (EPA) has established regulations via the Clean Water Act to restore and maintain the chemical, physical, and biological integrity of our nations waters. The Clean Water Act Section 303(d) requires states to compile lists of waterbody segments impaired by pollutants. The Total Maximum Daily Load (TMDL) is a technical calculation of the maximum load of pollutant a waterbody can receive and still meet water quality standards. The PA DEP has assessed the streams within Pennsylvania and established a 303(d) list which details impaired and threatened waters. The Shamona Creek Watershed is a sub-watershed to the Brandywine Creek Watershed / Christina River Basin (4.02 square mile watershed). Per the EPA 2006 TMDL for the Christina River Basin1, the Shamona Creek Watershed is part of the B11-sub-basin. Within the TMDL Reports, watersheds are allocated a total concentration of nutrients and other pollutants which are allowed to be discharged into a waterbody without reducing water quality standards. These allocations are comprised of Load Allocations (LAs) for non-point sources and Waste Load Allocations (WLAs) for point sources. Based upon the 2006 Total Maximum Daily Load (TMDL) Reports, there is no Load Allocations or Waste Load Allocations associated with the Shamona Creek or the B11 sub-basin at this time. Per PA DEP Final 2010 Pennsylvania Integrated Water Quality Monitoring and Assessment Report, which is the PA DEPs Clean Water Act Section 305(b) reporting and Section 303(d) listing, Shamona Creek and the unnamed tributaries have been assessed and determined to be not attaining water quality standards. The causes of impairments per the PA DEP 303(d) listing are:

Cause Unknown Siltation Water / Flow Variability

1 EPA Region III, Total Maximum Daily Loads for Bacteria and Sediment in the Christian River Basin, Pennsylvania, Delaware, and Maryland, September 2006, and Total Maximum Daily Loads of Nutrients and Dissolved Oxygen Under Low-Flow Conditions In the Christina River Basin, Pennsylvania, Delaware and Maryland, revised April 2006

Per the Pennsylvania Department of Environmental Protection (PA DEP) 25 Pa. Code Chapter 93 - Water Quality Standards, all three stream segments within the Shamona Creek Watershed designated use are High Quality - Trout Stocking Fishes, Migratory Fishes (HQ-TSF, MF).

The Shamona Creek Watershed is tributary to water supplies including private wells and the Downingtown Municipal Water Authority water source (East Branch Brandywine Creek). The Water Authority provides water to Downingtown Borough, Caln Township, East Caln Township, East Brandywine Township and West Bradford Township (over 10,000 population).

2.3 Existing Land Use

The Shamona Creek Watershed includes a diverse mix of land uses. The land cover types vary throughout the watershed but generally are found to be clustered in types and locations. The upper reaches of the watershed are dominated by commercial and office park developments with large parking lot areas. The area also includes major roadways and highway interchange areas.

The center of the watershed is predominately medium density single-family residential developments mixed with open space and small parks. The area is described as well manicured lawns and includes several natural and manmade ponds. The southern part of the watershed is generally single family, large lot residences. A significant portion of this watershed area is open space including the Township park system. Generally, the areas surrounding the main stem of the Shamona Creek are wooded. Per Exhibit 2.3A Existing Land Use Plan and data from the Uwchlan Township Comprehensive Plan Update, dated August 9, 2010, the following existing land uses areas are located within the watershed: Agricultural - 86.0 acres Residential (Single, Two and Multi-Family) 1,096.1 acres Commercial 386.5 acres Industrial - 0 acres Community Facilities 67.3 acres Park and Open Space 395.4 acres Vacant 180.5 acres Roadways (right-of-way) 301.5 acres


As noted above, the watershed does have 180.5-acres of vacant land, as depicted on Exhibit 2.3B Vacant / Developable Land Inventory Plan but for the most part the watershed is considered built-out. This vacant land represents approximately seven (7) percent of the total watershed area. Additionally, there are approximately 400 acres of park and open space within the watershed, as depicted in Exhibit 2.3C Open Space Inventory Plan. This represents approximately sixteen (16) percent of the total watershed area.

2.4 Land Cover

The existing land cover located within the Shamona Creek Watershed is a combination of manicured lawn, impervious coverages (roads, structures, driveways), and woodlands. There is minimal agricultural land within the watershed. The estimated land cover breakdown includes approximately twelve (12) to fifteen (15) percent of impervious coverage and approximately three (3) percent agricultural land.

2.5 Rainfall Data

Annual rainfall within Uwchlan Township is approximately 45.9-inches, as listed on the Chester County Water Resource Authority Chester County Water Resources Authority Volunteer Rainfall Observer Network data, November 2012. Per the National Oceanic and Atmospheric Administration (NOAA), the rainfalls within the watershed for the various storm events are as follows:

24-Hour Storm Event 2-year 3.25-inches 10-year 4.75-inches 25-year 5.73-inches 50-year 6.55-inches 100-year 7.43-inches


EXISTING LAND USE LEGEND

Exhibit 2.3A Existing LandUse Plan

PINECREEK

UNT EAST BRANCHBRANDYWINE

CREEK

LIONVILLERUN

COLEBROOK RUN

EAST BRANCHBRANDYWINECREEK

SHAMONA CREEK- MAIN STEM

UNT SHAMONA CREEK #1

SHAMONA CREEK -MAIN STEM

SHAMONACREEK -MAIN STEM


VACANT LAND INVENTORY LEGEND

Exhibit 2.3B Vacant /Developable Land Inventory

Plan

PINECREEK


CREEK

LIONVILLERUN

COLEBROOK RUN







OPEN SPACE INVENTORY LEGEND

Exhibit 2.3C Open SpaceInventory Plan

PINECREEK


CREEK

LIONVILLERUN

COLEBROOK RUN








2.6 Floodplain

Federal Emergency Management Agency (FEMA) has performed a detailed flood study for the Shamona Creek from the confluence with the East Branch of the Brandywine Creek to approximate 1.5-miles upstream. 2 As detailed on the FEMA FIRM maps (Exhibit 2.6A - FEMA Firm Map 145 and Exhibit 2.6B FEMA Firm 150), the floodplain generally parallels the stream channel for the majority of the study area. The floodplain expands outside the stream channel just upslope of the confluence with the East Branch of the Brandywine Creek. An analysis of the floodplain area has been completed by the Township and it was determined that the cause of the floodplain expansion at this area is the limited capacity under the Dowlin Forge Road bridge structure at the intersection with Shelmire Road. The bridge is a stone arch structure and per the bridge placard, the structure was County Bridge No. 257, constructed in 1915. The peak flow rate for the 100-year frequency storm was determined by FEMA to be 2,250 cubic feet per second (cfs). The capacity of the 1915 bridge structure is approximately 800 cfs which is approximately the equivalent of the five (5) year storm event. Severe flooding has been observed within the watershed during a variety of storm events during the last fifteen year. Major storm events include including but not limited to the following:

September of 1999 - Hurricane Floyd September 2003 - Hurricane Isabel September 2005- Hurricane Katrina August 2011 - Hurricane Irene

These storm events have caused large scale streambank erosion, loss of trees within the floodplain area and damage to existing bridges and culverts. As part of various land development projects, the floodplain, upslope of the FEMA studied area, has been analyzed and the 100-year floodplain has been mapped. The floodplain generally parallels the stream corridor at various widths dependent

2 Federal Emergency Management Agency (FEMA) Flood Insurance Rate Maps, 42029C0145F and 42029C0150F dated September 29, 2006.

on the topography. The floodplain expands significantly at the Wharton Boulevard Dam structure as this facility is an in-line stormwater management control basin.


MattRectangle

MattTypewritten TextShamona Creek Watershed Plan

MattTypewritten TextExhibit 2.6A FEMA

MattTypewritten TextFIRM MAP 145

MattTypewritten TextUwchlan Township, Chester County, PA

MattRectangle

MattTypewritten TextShamona Creek Watershed Plan

MattTypewritten TextExhibit 2.6B FEMA

MattTypewritten TextFIRM MAP 150

MattTypewritten TextUwchlan Township, Chester County, PA

3 Existing Conditions Inventory 3.1 Stream Encroachments

As with most developed watersheds, there are numerous stream encroachments along the Shamona Creek and the unnamed tributaries. As detailed in Exhibit 3.1 Stream Encroachment Inventory Plan, the following encroachments were noted:

Nearest Encroachment No. Road Intersection Description

Shamona Creek Main Stem 1 Dowlin Forge Road Shelmire Road 1915 stone arch

2 Crooked Bridge - Dowlin Forge Rd Fillman Road 1907 brick & stone arch

3 Dowlin Forge Road Shamona Creek Park 1965 non-composite prestressed box beam bridge

4 Dowlin Forge Road Kingston Lane 1942 reinforced concrete t-beam bridge

5 North Milford Road Cul-de-sac 11' x 7' stone arch

6 Wharton Boulevard Gramercy Lane 17' x 10' box culvert

7 Eagleview Boulevard Regency Drive 6' x 12' box culvert

8 Route 100 Turnpike Ramp 72" RCP

Unnamed Tributary - Pennypacker Road 9 Pennypacker Road Kingston Lane 42" CMP conc. endwalls

Unnamed Tributary #1 - Eagleview Shamona South 10 Wharton Boulevard Deep Willow 72" CMP conc. endwalls

Unnamed Tributary #2 - Shamona Creek Park (Seasons)

11 Peck Road Park entrance 3-42" CMP conc. endwalls

12 Taylor Road Nancy Jane Lane 2-48" RCP

13 Deep Willow Drive (north) Laurel-Moors Drive 2-48" RCP

14 Deep Willow Drive (south) Laurel-Moors Drive 2-72" CMP


Analysis of the capacity of the encroachments has not been prepared as part of this Watershed Plan. Based upon Township knowledge of the watershed, the only encroachment that is known to have capacity issues is encroachment #1 adjacent at Shelmire Road. During a study commissioned by Uwchlan Township in the 2006, the lower reaches of the floodplain were analyzed and it was determined that this encroachment only has the capacity to pass a flow roughly equivalent to the five (5) year storm event. In addition to the above listed encroachments, there are five (5) pedestrian bridge crossings over the Shamona Creek constructed as part of the Uwchlan Township Trails system in 1998. The prefabricated metal truss bridges have been placed above the 100-year flood elevation.


ENCROACHMENT INVENTORY LEGEND

Exhibit 3.1 StreamEncroachment Inventory Plan

PINECREEK


CREEK

LIONVILLERUN

COLEBROOK RUN


14

13

12

11

3

2

1

4

9

5

6

7

8






1

3.2 Sanitary Sewage Treatment Facilities

The majority of the properties within the Shamona Creek Watershed are served by public sewage system. The public sewer system consists of collection and conveyance facilities and two treatment / disposal facilities. In addition to the public sewage system, it is estimated that approximately 25 to 30 residential properties have on-lot sewage treatment systems. Uwchlan Township owns and operates the Townships public sewage collection and conveyance facilities. The Township Public Works Department is responsible for the operation and maintenance of these facilities. As part of the maintenance program, the Township regularly inspects the facilities to ensure no illicit discharges into the watershed occur. The wastewater is collected and conveyed to either the Downingtown Area Regional Authority (DARA) facility in Downingtown Borough or the Uwchlan Township Municipal Authoritys Eagleview Wastewater Treatment Plant (Eagleview WWTP). DARA is a multi-municipal organization which provides treatment to the wastewater prior to discharge to the East Branch of the Brandywine Creek. This discharge is located downstream of the Shamona Creek Watershed. The Eagleview WWTP is situated within the Shamona Creek drainage basin and provides wastewater treatment for the Eagleview residential and commercial development. The treatment processes include biological treatment by the extended aeration process, sand filtration, chemical addition for the removal of phosphorous and ultraviolet treatment for wastewater disinfection. The treatment plant discharges treated wastewater indirectly to the Shamona Creek through wetlands. The discharge is located upslope of the Eagleview Boulevard Dam. The current flow to the Eagleview WWTP, which has a design capacity of 475,000 gallons per day, is approximately 160,000 gallons per day. The treatment plant discharge is regulated by NPDES Permit No. PA0054917. The treatment plant has consistently met the permitted effluent limits, which include the following:

Carbonaceous biochemical oxygen demand: 6 mg/l (May 1 to October 31) 12 mg/l (Nov. 1 to April 30) Total suspended solids: 20 mg/l Ammonia as nitrogen: 0.8 mg/l (May 1 to October 31) 2.4 mg/l Nov. 1 to April 30)


Phosphorous as P: 0.8 mg/l (May 1 to Oct. 31) 1.6 mg/l (Nov. 1 to March 31) Dissolved oxygen: 6.0 mg/l (minimum) pH: 6.0 to 9.0

The on-lot sewage disposal systems are located throughout areas of the watershed where connections to the public sewer are not available. The Chester County Health Department regulates all on-lot sewage systems and requires maintenance on the facilities. There are no known issues with the existing on-lot systems.

3.3 Stormwater Management Facilities

With the urbanization of the watershed, there has been a significant amount of stormwater infrastructure constructed. The infrastructure consists of stormwater management basins, conveyance systems and numerous in-line facilities along the stream corridor. Recent development, approved after 2003, have stormwater management facilities that control both the peak discharge rate and the volume of runoff generated by the improvements. An extensive review of development plans and various site investigations have been performed to determine the location and conditions of various basins. As Within this report is a Stormwater Management Inventory Plan (Exhibit 6.3) that depicts the locations and approximate drainage areas for many of the significant stormwater facilities located within the watershed. The facilities depicted on this plan are not an all encompassing tabulations of facilities. As part of the Townships Municipal Separate Storm Sewer System (MS4) Permit, the Township is working on preparing an overall stormwater management facility map that depicts all conveyance facilities, outfalls and control facilities. This map will be used as part of the Illicit Discharge Detection and Elimination program and can be utilized during the planning process for watershed improvement projects.


4 Watershed Studies

The Brandywine Valley Association (BVA) watershed group has recently completed the following reports that included the Shamona Creek Watershed:

BVA Assessment Report for Shamona Creek and East Branch Brandywine

Creek Watersheds Chester County, Pennsylvania, dated April 2010

BVA Restoration Plan for Shamona Creek and East Branch Brandywine Creek Chester County, Pennsylvania, dated May 2010.

4.1 Assessment Report for Shamona Creek Watersheds

The 2010 BVA Assessment Report documents existing stream conditions and potential sources of watershed impairment. A stream walk (on-ground survey) was conducted and aquatic investigations at various sample stations within the watershed were performed. The investigations included benthic macroinvertebrate sampling and habitat analysis, as well as physical and chemical water quality sampling. Aquatic investigations at five (5) sample sites were performed within Shamona Creek Watershed (sites 11-15). As per the BVA Assessment Report Table 7, all five (5) sample locations were impaired in regards to benthic macroinvertebrate community, one (1) site was impaired for habitat and three (3) locations were impaired for phosphorus. No sites within the watershed were impaired for nitrogen.


BVA Assessment Report - Table 7 (excerpt) Impaired Stream Reaches Site 11 12 13 14 15 Macros I I I I I Habitat NI NI NI NI I Phosphate I NI I I NI Nitrate NI NI NI NI NI Key:

I Impaired NI Not Impaired

Site Description: Site 11: Lower reach of Shamona Creek (upslope of confluence with the East

Branch of the Brandywine Creek).

Site 12: Upstream of confluence with Unnamed Tributary #2 at Shamona Creek Park.

Site 13: Lower reach of Unnamed Tributary #2 at Shamona Creek Park. Site 14: Shamona Creek main stem upstream of Unnamed Tributary #1 at

Wharton Dam. Site 15: Lower reach of Unnamed Tributary #1 at confluence with main

stem of Shamona Creek (rear of Eagleview Apartments).


4.2 Restoration Plan for Shamona Creek

The 2010 BVA Restoration Plan summarizes the issues noted in the studied watersheds and recommends solutions to address the issues. Solutions to address the issues are broken down into high priority and medium priority projects. Three (3) high priority projects and two (2) medium priority projects are recommended for the Shamona Creek Watershed. The recommended projects include:

A. High Priority

1. Impacted Stream Segment #73-74. Upslope of Eagleview Boulevard Dam. Recommendations: Restoration of eroded stream channel.

2. Impacted Stream Segment #76. Eagleview Boulevard Dam Pond. Recommendations: Install a vegetative buffer around pond and retrofit pond weir for fish and reptile migration.

3. Impacted Stream Segment #79-84 and 80-84. Wharton

Boulevard Dam. Recommendation: Analyze dam structure to ensure optimum performance. Removal of accumulated sediment upslope of dam and stabilize eroded streambanks.

B. Medium Priority

1. Impacted Stream Segment #87-88. West of Ferncastle Drive cul-de-sac. Recommendations: Stabilize eroded streambanks, install stabilized channel at rip-rap location and removal of non-functioning dam structure.

2. Impacted Stream Segment #100. Shamona Creek main stem, south of Filman Road. Recommendation: Stabilize severely eroded streambank at HOA owned property downslope of Dowlin Forge Road crooked bridge.


BVA RESTORATION PLAN LEGEND

Exhibit 4.2 BVA AssessmentReport and Restoration Plan

Location Map

PINECREEK


CREEK

LIONVILLERUN

COLEBROOK RUN


11

13

12

15

14

7374

7679

80

8483 8281

8788

100






111

5 Municipal Regulations

5.1 Township Stormwater Management Ordinance.

Stormwater management is currently regulated by the Uwchlan Township Stormwater Management Ordinance, Ordinance No. 2 of 2005, adopted May 9, 2005. At the time of adoption, this ordinance was consistent with the applicable state regulations. The 2005 Ordinance regulates all land development activities including building permit plans, and any improvements that involve the construction of new impervious surfaces greater than 1,000 square feet and / or earth disturbance activities that disturb more than 5,000 square feet. The ordinance requires:

Section 405. Groundwater Recharge. The net increase volume of runoff that occurs during the two-year storm event must be captured and infiltrated.

Section 406. Water Quality Requirements. Water quality best management practices to be implemented to improve water quality for the first one (1) inch of rainfall.

Section 407. Stream Bank Erosion Requirements. In order to minimize the impact of improvements, the two-year storm event peak discharge rate must be reduced to the one-year peak discharge rate.

Section 408. Stormwater Peak Rate Control. The post developed peak rate of runoff must be reduced to the existing conditions peak rate of runoff for all storm events including the two-year to the 100-year events.

Prior to the adoption of this ordinance, stormwater management was regulated by the Township Subdivision and Land Development Ordinance, Ordinance No. 79-02, adopted June 11, 1979.

5.2 Township Comprehensive Plan

The Uwchlan Township Comprehensive Plan has been recently updated in 2010. The 2010 Comprehensive Plan Update includes an inventory and analysis of existing conditions within the Township and establishes overall Township goals and procedures for implementation of the goals. The goals are detailed in Chapter 5 of the Comprehensive Plan and are broken into two categories, Short-Range Strategies and Long-Range Strategies. Strategies that would assist with achieving the goals of this Watershed Plan include:


A. Zoning Ordinance Land Use. Emphasize the use of the Residential Open Space Option for undeveloped tracts to set aside open space for the preservation of sensitive natural features and the minimization of additional impervious.

B. Zoning Ordinance - Create regulations that require Open Space Management Plans to be created for new development which detail the management and maintenance responsibilities for open spaces in new developments.

C. Zoning Ordinance Consider the creation of steep slope regulations that restricts or prohibits development and impervious surfaces within the steep slopes.

D. Subdivision Ordinance Update the current Stormwater Management Ordinance to include additional Best Management Practices (BMPs).

E. Zoning Ordinance Update the Zoning Ordinance to include tree protection and replacement standards within the Environmental Impact Assessment.

F. Land Use Preserve the floodplain and wetland area within the 27-acre Nelson Property south of the PA Turnpike.

G. On-going Strategies Continue the Township policy of including sensitive water resource areas within the open space of developments.

H. Open Space Planning Incorporate the undeveloped tract south of Windham, planned for Medium Density Residential, into the Township open space network as the open space created protects wetland areas and provided for a connection to the existing Windham open space.

I. Open Space Planning Continue to acquire through the open space within the development process, conservation easement, or actual purchase, a buffer along the Shamona Creek.

J. Recreation Lands & Facilities Evaluate and consider the acquisition of the Pennypacker Country Club, if the property becomes available.

5.3 Township Zoning Ordinance

The Township Zoning Ordinance reflects the land use policies from the Township Comprehensive Plan and was originally prepared in 1994. Numerous amendments have been made since the 1994 adoption. Section 510 FP Floodplain District has been amended to provide regulations for riparian buffers. Per Section 301, a Riparian Setbacks and Buffer Area is an undeveloped, vegetated corridor 50-foot in width generally parallel to any permanent or intermittent stream, river, brook, creek, lake, pond, one-hundred-year floodplain, or wetland. Section 510 regulates the permitted uses and restrictions within a Riparian Setback and Buffer Area and requires the


preservation of woodlands, limits the impervious coverage and encourages the reforestation of the setback and buffer area.

Land use regulations within the Zoning Ordinance include options for Residential Open Space Option, Planned Single Family Development and Planned Commercial Industrial District (PCID). These land use regulations promote the creation of open space within the development.

5.4 Township MS4 Permit

Uwchlan Township owns and operates a regulated small Municipal Separate Storm Sewer System (MS4) and has a National Pollutant Discharge Elimination System (NPDES) MS4 Individual Permit (PAI-130505). As an operator of a regulated small MS4, Uwchlan Township has developed and implements a stormwater management program which includes six (6) Minimum Control Measures (MCM) as required by the Pennsylvania DEP. The MCMs are intended to reduce the amount of pollutants that are discharged into the watershed. The six MCMs are:

1. Public Education and Outreach 2. Public Participation/Involvement 3. Illicit Discharge Detection and Elimination 4. Construction Site Runoff Control 5. Post-Construction Runoff Control 6. Pollution Prevention/Good Housekeeping

The Township has been operating the MS4 Stormwater Program since 2003 with assistance from the Brandywine Valley Association (BVA) watershed group. The BVA provides a valuable resource to Uwchlan Township and other local municipalities assisting with the Public Education and Outreach and the Public Participation/Involvement minimum control measures.


6 Watershed Improvement Goals and Issues

The objective of this Watershed Plan is to develop a strategy for the shareholders of the watershed to utilize to improve the water quality and natural hydrologic regime of the watershed so that all streams are attaining state water quality standards. The watershed improvement goals can be further defined as:

1. Improve Stream Habitat. 2. Protect and Restore Stream Corridors, including riparian buffers and

floodplains. 3. Reduce Flooding.

Per the BVA Assessment Report for Shamona Creek and East Branch Brandywine Creek Watersheds Chester County, Pennsylvania April 2010, portions of the Shamona Creek and the tributaries are impaired for the following:

benthic macro invertebrate community habitat phosphorus

Per the 2010 PA DEP Final Pennsylvania Integrated Water Quality Monitoring and Assessment Report, the causes for the Shamona Creek impairments are noted as:

Cause Unknown Siltation Water / Flow Variability

This Watershed Plan establishes a list of recommendations for projects that can be implemented by the shareholders to achieve the desired result of improving water quality and the natural hydrologic regime.


6.1 Cause of Impairments Discussion

The impairment to the benthic macro invertebrate community and the overall stream habitat are caused by a variety of sources.

A. Streambank / channel bed erosion causes siltation which negatively impacts

habitat. The cause of the erosion can be attributed to the following: Urbanization / development of the watershed

o Increase volume of runoff o Water / Flow Variability

Steep natural terrain of the lower reach of Shamona Creek. Poor stream bank stability

B. The Urbanization of the watershed has altered the natural hydrologic regime by

reducing the natural infiltration and natural water flow, and increasing the volume of runoff. Runoff from the improvements have been collected and conveyed either:

Directly to streams for the older developments built prior to the stormwater management regulations.

To centralized detention basins for projects constructed in the 1980s and 1990s.

To infiltration facilities or other best management practices (BMPs) such as infiltration basins / beds for projects constructed in the 2000s.

When a land area is altered from a natural forested ecosystem to an urbanized land use consisting of rooftops, streets and parking lots, the hydrology of the system is significantly altered. Water which was previously ponded on the forest floor, infiltrated into the soil and converted to groundwater, utilized by plants and evaporated or transpired into the atmosphere is now converted directly into surface runoff. An important measure of the degree of urbanization in a watershed is the level of impervious surfaces. As the level of imperviousness increases in a watershed, more rainfall is converted to runoff. The urbanization of a watershed directly corresponds to the water / flow variability listed in PA DEP 2010 Pennsylvania Integrated Water Quality Monitoring and Assessment Report.

C. Phosphorus. As per the 2010 BVA Assessment Report, three (3) of the sample

locations were impaired for phosphorus. In water, phosphorus behaves as a fertilizer, accelerating plant and algae growth. When plants and algae die,


bacteria consume oxygen that is dissolved in the water. When this happens, less oxygen is available for fish and aquatic life that need oxygen to survive. Generally, sources for phosphorus include wastewater treatment plants and other nonpoint sources, such as stormwater runoff, septic tanks, and agriculture. Phosphorus is in leaves, lawn clippings, animal wastes, some lawn fertilizers and most garden fertilizers, and is attached to soil. When leaves, lawn clippings, animal wastes, fertilizers, and soil are picked up by stormwater runoff and are carried directly to the waterways, they provide the ponds and streams with excess phosphorus. This excess phosphorus causes increased algae growth. Algae are small green plants that live in lakes and streams. Increased algae growth is observed as green algae blooms or scums on ponds. Too much algae is harmful to a stream and pond systems. It blocks sunlight and prevents other plants from growing. When it dies and decays, it also takes much needed oxygen away from fish.

The urbanization of this watershed contributes to the phosphorus impairment.

Most of the causes of impairments and the impairments themselves are directly related to one another. The Shamona Creek Watershed has seen significant development over the last fifty (50) years which has altered the natural hydrologic regime of the watershed. This urbanization has created water / flow variability which in returns causes streambank and channel erosion. The erosion increases the silt within the stream channels and local ponds which cause impairments to the stream habitat including the macro invertebrate community. A significant cause of the various impairments is the urbanization of the watershed. This urbanization has caused an increased volume of runoff, flooding of stream channel and erosion of the streambanks and channels.

6.2 Urbanization of the Watershed Discussion

The urbanization of Uwchlan Township can be attributed to proximity of the region to the significant highways and various commercial districts. Within Uwchlan Township, there is the Downingtown Interchange of the Pennsylvania Turnpike. This interchange was constructed in 1949. The interchange connects the Turnpike to State Route 100 - Pottstown Pike which is the major north / south access route of Chester County. Also within Uwchlan Township is State Route 113 Uwchlan Avenue. Route 113 is an arterial street connecting the Borough of Downingtown to the Township and beyond to Chester Springs and Phoenixville Borough. The adjoining Township of West Whiteland Township is a major


commercial district of the County and has the Exton Square Mall which opened in 1973. So a combination of major roadways and commercial districts has made Uwchlan Township a prime development area.

Census Population Population

Increase % Increase

1930 507 1940 599 92 18.1% 1950 761 162 27.0% 1960 995 234 30.7% 1970 5,473 4478 450.1% 1980 8,364 2891 52.8% 1990 12,999 4635 55.4% 2000 16,576 3577 27.5% 2010 18,088 1512 9.1%

Throughout the years of development from the 1960s to the present time, the Township has protected a significant amount of land from future development. This land has been dedicated to the Township as open space or parkland or has been set aside as homeowners association open space. Within the Shamona Creek Watershed, there is approximately 400 acres of open space / parkland. Along the 3.87-mile stream corridor of the main stem of the Shamona Creek, there are approximately 2.4-miles of stream corridor with significant stream buffers (100-foot+).

6.3 Identification of Pollution Sources

In order to achieve the goals of this Watershed Plan and identify potential improvements to the watershed, the sources that cause the impairments need to be identified. Stormwater pollution sources can be separated into two categories; Non-point Source and Point Source. In general, non-point source pollution accounts for over 75% of Pennsylvanias total water pollution problem.

Point Source Pollution refers to pollution originating from a defined source such as an outfall pipe or ditch. Non-Point Source Pollution typically refers to pollution originating from diffuse sources that does not originate from a single defined source.


6.3.1 Point Source Pollution

Based upon field observations, the predominant source of stormwater pollution from this watershed is point source pollution. The urbanization of the watershed has developed significant infrastructure, including roadways, underground conveyance systems (storm sewer), above ground conveyances systems (swales) and stormwater management facilities (basins, underground beds). The facilities were generated throughout the year as follows:

Within the pre-1970s developments, there are no or minimal stormwater management facilities available to treat the point sources prior to discharge into the streams or ponds within the Township.

The developments that occurred in the 1970s to the 1990s have stormwater management facilities that control the rate of runoff with no controls for the volume or water quality.

Development that occurred within the 2000s, typically have stormwater management control facilities that control: o Peak rate of runoff. o Volume of runoff from the 2-year storm event. o Water quality.

An inventory of the stormwater management systems within the watershed were undertaken as part of this Watershed Plan. Exhibit 6.3 - Stormwater Management Inventory Plan depicts the location and approximate drainage areas for many of the stormwater management facilities located within the watershed. This plan is not an all exclusive listing of all facilities as information for all development projects were not available.

6.3.2 Non-Point Source Pollution

Non-point source pollution sources can originate from a number of different sources. Typical sources include:

a. On-lot sewage disposal systems. b. Agricultural land. c. Erosion and sedimentation from construction sites. d. Lawn and garden chemicals, including pesticides, herbicides and fertilizers. e. Uncontrolled runoff discharges from roadways or parking facilities,

including driveways.


a. On-lot sewage disposal systems. Due to the limited number of on-lot sewage disposal systems within the Shamona Creek Watershed, it is not anticipated that these systems are a significant contributor to non-point source pollution. The majority of development within the Township is served by a public sewer. The Eagleview Wastewater Treatment Plant, which is located within the watershed, currently meets and has met the permitted effluent limits as established by the PA DEP.

b. Agricultural land. Due to the limited agricultural land within the watershed,

it is not anticipated that there is a significant amount of non-point source pollution from agricultural land. There is only one parcel of land within the Shamona Creek Watershed that is an agricultural land use. The Happy Days Farm, located at the top of the watershed, adjacent to the Pennsylvania Turnpike Interchange and Route 100, is an active farm. The farm is 246-acres and is owned by the Nelson Realty Trust, a real estate holding company for the Vanguard Group. The farm is currently operated by a tenant. To the best of our knowledge, this agricultural use does not have an approved Conservation Plan.

c. Erosion and sedimentation from construction sites may contribute to the

non-point source pollution within the watershed. These sites are regulated by the Township via the 2005 Stormwater Management Ordinance and the County Conservation District (for projects with earth disturbances greater than one (1) acre).

d. Lawn and garden chemicals may be a significant non-point pollution source.

The majority of the residential lands have well manicured lawns that most likely use weed control / fertilizers.

e. Uncontrolled runoff from roadways, parking facilities and driveways may

also be a significant non-point pollution source for this watershed.


SWM INVENTORY LEGEND

1

Exhibit 6.3 StormwaterManagement Inventory Plan


PINECREEK


CREEK

UNT SHAMONA CREEK #1LIONVILLERUN




COLEBROOK RUN


LEGEND

7 Watershed Improvement Recommendations

The goals of this Watershed Plan include: Improve Stream Habitat. Protect and Restore Stream Corridors, including riparian buffers and

floodplains. Reduce Flooding.

As part of this Watershed Plan, a series of recommendations have been made to help achieve the above referenced goals. The recommendations are broken down into four (4) categories.

1. Land Use Planning 2. Stormwater Management Planning 3. Public Education and Outreach 4. Watershed Improvement Projects

7.1 Land Use Planning

Land Use Planning is a tool that can be utilized by the Township to achieve the goals of this Watershed Plan by implementing regulations that protect the natural resources, promote open space and manage redevelopment. Within the Shamona Creek Watershed, there are approximately 180.5-acres of vacant / developable land. The locations of this land are depicted on the attached Exhibit 2.3B Vacant / Developable Land Inventory Plan. This vacant / developable land represents approximately seven (7) percent of the total land area within the watershed. A significant portion of this land is constrained with natural resources including floodplain, wetlands and steep slopes. In order to achieve the goals of this Watershed Plan, the protection of the natural resources on these vacant parcels is important. The 2010 Uwchlan Township Comprehensive Plan Update has detailed numerous Short-Range and Long-Range Strategies that can be utilized by the Township in the land use planning for these parcels. These strategies include:

A. Zoning Ordinance Land Use. Emphasize the use of the Residential Open

Space Option for undeveloped tracts to set aside open space for the preservation of sensitive natural features.

B. Zoning Ordinance - Create regulations that require Open Space Management Plans to be created for new development which detail the


management and maintenance responsibilities for open spaces in new developments.

C. Zoning Ordinance Consider the creation of steep slope regulations that restricts or prohibits development and impervious surfaces within the steep slopes.

D. Zoning Ordinance Update the Zoning Ordinance to include tree protection and replacement standards within the Environmental Impact Assessment.

E. Land Use Preserve the floodplain and wetland area within the 27-acre Nelson Property south of the PA Turnpike.

F. On-going Strategies Continue the Township policy of including sensitive water resource areas within the open space of developments.

G. Open Space Planning Incorporate the undeveloped tract south of Windham, planned for Medium Density Residential, into the Township open space network as the open space created protects wetland areas and provided for a connection to the existing Windham open space.

H. Open Space Planning Continue to acquire through the open space within the development process, conservation easement, or actual purchase, a buffer along the Shamona Creek.

I. Recreation Lands & Facilities Evaluate and consider the acquisition of the Pennypacker Country Club, if the property becomes available.

With assistance from the Chester County Planning Commission via the Vision Partnership Program (VPP), Uwchlan Township has been proactive to address the 2010 Comprehensive Plan Update regulatory recommendations by preparing Zoning Ordinance amendments and a new Subdivision and Land Development Ordinance (SALDO). It is anticipated that the Zoning Amendments and the SALDO will be adopted in 2013. The Amendments and SALDO will help achieve the goals of this Watershed Plan. Land Use Planning Recommendations: The Comprehensive Plan has outlined a series of general strategies that will help achieve the goals of this Watershed Plan. The Township should continue to be proactive with the implementation of these goals, including but not limited to:

1. Finalize and adopt the Zoning Ordinance Amendments and Subdivision

and Land Development Ordinance.


2. Property owners and the Township should work together to develop sustainable designs that benefit the watershed and the fellow shareholders of the watershed.

3. Also as mentioned in the 2010 Comprehensive Plan Update, an on-going

implementation strategy of the Township is to promote energy efficiency standards, such as Leadership in Energy and Environmental Design (LEED) for the development and redevelopment of buildings, properties, and neighborhoods. LEED Design projects incorporate design elements that would help achieve the goal of this Watershed Plan such as green roofs to control runoff volume and infiltration design best management practices such as rain gardens, porous pavement and biofiltration areas.

4. The Township should continue to evaluate vacant parcels of land for

preservation including but not limited to buffers surrounding Shamona Creek and its tributaries, and the Pennypacker Country Club.

7.2 Stormwater Management Planning

Uwchlan Township is responsible for regulating stormwater management from all new development that occurs within the Township. The Townships 2005 Stormwater Management Ordinance is the regulative tool used to control stormwater generated from new development. The current Township Ordinance is based upon an Act 167 model ordinance and is generally consistent with current PA DEP National Pollutant Discharge Elimination System (NPDES) requirements.

The Pennsylvania Stormwater Management Act 167 requires counties to prepare, periodically update and adopt Plans for all stormwater management watersheds. The Chester County Water Resource Authority (CCWRA) is currently in the final stage of the County-wide Act 167 Stormwater Management Plan for Chester County, PA. The Final Act 167 Plan will produce a model stormwater management ordinance that Uwchlan Township is required to adopt within six (6) months of PA DEP approval of the Plan. This ordinance will strengthen stormwater management regulations and update various regulatory requirements to be consistent with the recent changes to the NPDES permit requirements, PA Title 25 Chapter 102 Erosion and Sediment Pollution Control Program and the December 2006 Pennsylvania Stormwater Best Management Practices Manual. The model ordinance from the County-wide Act 167 plan will strengthen several key components of the Township regulations which will assist achieving the goals of this Watershed Plan including but not limited to the following:


Stormwater volume control. The model ordinance has regulations regarding

water volume controls in addition to the infiltration requirements. The current ordinance requires groundwater recharge for a recommended amount with step down requirements for sites in which the soil conditions do not support the full recharge requirement.

Soil test requirements. The model ordinance updates the soil test requirements

based upon current industry procedures. The will produce more accurate designs that area sustainable over the long term.

Loading ratios for infiltration facilities. The model ordinance provides

regulatory requirements to comply with the PA DEP BMP manual for total drainage area and impervious area loading ratios.

Operation and Maintenance of Post Construction Stormwater Management

facilities. The model ordinance strengthens the requirements for post construction maintenance of stormwater management facilities within new development by the current and future property owners. The regulatory requirement will ensure the long term operation and maintenance of the stormwater management facilities.

Upon adoption of the Act 167 Plan by the County and approval by the PA DEP, Uwchlan Township must adopt the Act 167 Stormwater Management Ordinance. This ordinance will be the regulatory tool to minimize or eliminate the impacts of new stormwater runoff on the existing streams. Reduction of stormwater runoff into the stream will aid in eliminating streambank erosion and improving turbidity. Additionally, maintaining the existing stream flow in the stream will assist with the year round habitat.

7.3 Public Education and Outreach

In order to achieve the goals of this Watershed Plan, it is important to involve all shareholders of the watershed. It is not the responsibility of one entity to improve the watershed but all shareholders including but not limited to the Township, property owners, developers, business owners, employees of the local businesses and users of the Township parks, open spaces and trail systems. Education of these shareholders is key to make noticeable improvements to the watershed. Currently Uwchlan Township implements a stormwater management program that meets the regulatory requirements of the PA DEP National Pollutant


Discharge Elimination System (NPDES) Phase II Municipal Separate Storm Sewer System (MS4) program. This program is intended to reduce the amount of pollutants that are discharged into the watershed. As part of this program, the Township must implement a Public Education and Outreach program to distribute educational materials to the community, or conduct equivalent outreach activities about the impacts of stormwater discharges on local waterbodies and the steps that can be taken to reduce stormwater pollution. As part of the current Township MS4 stormwater program, the Township has identified various shareholders within the watershed and outlined methods to educate those shareholders about stormwater management. With the assistance of the Brandywine Valley Association (BVA) watershed group, the Township meets the regulatory requirements of the permit by:

Placing stormwater management advertisements in local newspapers. Supporting various education programs sponsored by the BVA. Including educational material on stormwater management at the

Township office and the Township Parks for the general public. Including articles within Township newsletters regarding stormwater

management issues. On the Township Website, provide information regarding the MS4 program

and links to PA DEP Water Management program. Provide stormwater management education material with building permit

applications and at pre-construction meetings with developers / contractors.

Distribute stormwater management education material with Welcome Packs to new residents within the Township.

Since the inception of the Uwchlan Township MS4 stormwater management program in 2003, the public education and outreach has targeted a variety of general issues regarding stormwater management pollution. Utilizing the data from the 2010 BVA Assessment Report and 2010 BVA Restoration Report along with other data gathered as part of this Watershed Plan, it is recommended that the education program be expanded to target site specific watershed issues, including but not limited to:

Phosphorus pollution Streambank stabilization Streambank and pond riparian buffers Water quality improvements such as detention basin retrofits


Volume controls including rain barrel installation, rain gardens, and impervious surface disconnects

Consideration should be given to expand the educational outreach to target groups such as pond owners and homeowners associations regarding site specific issues. There is an abundant amount of education resources available from local watershed groups, county agencies and state agencies that can be utilized. In addition, consideration should be given to conduct public education workshops to discuss the issues within the watershed. Local watershed groups such as the BVA and potentially the County Conservation District may be available to assist with the coordination of these workshops.

7.4 Watershed Improvement Projects

During the watershed assessment process, specific areas were identified that had the potential to be improved. The identified improvement areas are not intended to be a fully comprehensive list but to act a guidebook for the shareholders of the watershed to utilize to achieve the goals of this Watershed Plan. The improvement projects are broken down into three (3) categories:

Streambank Stabilization projects Land Use / Land Cover Improvement projects Stormwater Management Facility Improvement projects

7.4.1 Streambank Stabilization Projects

Streambank erosion is a natural process that can be accelerated due to a variety of causes, including the urbanization of the watershed. Numerous studies have demonstrated that streambank erosion contributes a large portion of the annual sediment load within a watershed. This sediment load created by the bank / channel erosion negatively affects the overall habitat within the streams. Addressing this erosion is critical to the overall watershed water quality. In general, land use activities can negatively affect the stability of the banks by increasing the volume of runoff and destroying the natural vegetation that occurs in the riparian corridors along the stream channel. Due to the nature of the topography (steep streambanks and large channel elevation changes) and the highly erodible soils located along the creek, the lower portion of Shamona Creek has experienced significant streambank erosion over the years. The Township and residents within the watershed have been very


proactive to address this erosion. Numerous stabilization projects have been completed on Township property and on private property. The stabilization projects that have been undertaken have generally used hard armor practices (large rock). Methods to address the streambank erosion vary depending on the location of the erosion, the channel slope and resultant water velocity, existing vegetative cover and construction access. In general, varies construction methods may include:

Coir Logs Coir Logs are tightly bound cylinders of coir fibers (coconut fiber) held together by coir fiber netting made from coir twine. They are generally available in 10 to 20 foot lengths and are 12 to 20 inches in diameter. They are excellent to use as a toe protection in areas of low velocity water flow. After installation, the coir fiber log becomes saturated with water and vegetation can be planted directly on the logs. Coir fiber logs are eco-friendly; they provide a natural appearance and decompose over a three to five year period by which time the plants establish their root into the bank helping to stabilize erosion. Coir rolls are installed by making a shallow trench along the toe of the streambank. The coir rolls are placed in the trench so that the bottom and back are together with the streambank. They are secured at the toe of the slope using wooden stakes along both sides. Nylon or coir twine is used to secure the coir logs around the wooden stakes and the stakes are driven down firmly, securing the coir fiber roll to the streambed. The advantage of the coir log system is that they can be transported into the site manually therefore eliminating equipment damage to the surrounding streambank and floodplain. The general costs range, depending on size and quantity, $12 / 12 inch diameter to $25 /20 diameter.

Fascines Live fascines (LF) and inert fascines (IF) are cylindrical shaped bundled structures made from cuttings of living woody plant material. In the LF, the cut branches are expected to grow producing roots and top growth, (performing additional soil reinforcement via the roots and surface protection via the top growth). The LF is used from the base flow elevation and up along the face of an eroded streambank, acting principally to protect the bank toe and bank face. They are also useful over the crown to improve erosion control, infiltration, and other riparian zone functions. The IF is not intended to grow, but can be used to protect the toe of the streambank while other vegetation becomes established. The LF and IF can also be configured to act as current deflectors and pole drains that collect and transport water. Both have the potential to accumulate sediment.


Live Fascines and inert fascines benefit fisheries habitat by providing food and cover when they are used in close proximity to the edge of the stream. Stone used at the base of the LF or IF provides substrate for an array of aquatic organisms. Some of these organisms adapt to living on and within the rocks while others utilize the leaves and stems for habitat or as food. LF or IF can improve water quality and aesthetics. Plants within the LF or IF can be selected to provide color, texture, and other attributes that add a pleasant, natural landscape appearance, assimilate contaminants within the water column, and reduce non-point pollution by intercepting sediment and attached pollutants coming into the stream from flow and overbank areas. The advantage is similar to the coir log since they can be transported manually. The average costs are also dependent on size and generally range within the same cost range as coir logs.

Hard Armoring / Rock Protection The streambank stabilization method of hard armoring includes the placement of rock riprap and / or gabion baskets along the streambanks to protect the soil from erosion. Gabions baskets are rock-filled wire baskets). Hard armoring may require grading the bank to a gentler slope. This technique provides very good protection and will work in severe situations where vegetative methods may not be suited. This technique is typically more expensive than other techniques due to the construction equipment and material costs. Rock size is based upon stream flows and velocity and it is recommended that a cut-off trench be installed at the toe.

Riparian Buffer Restoration A riparian buffer is a permanent area of trees, shrubs and specific seeded areas adjacent to streams, ponds and wetlands. The buffer areas provide the last cleaning and provide ecological and water quality benefits. Riparian forests are


the most beneficial since they also add shade and temperature control for the existing waterway.

In order to improve the water quality within the Shamona Creek Watershed, it is recommended that areas of streambank erosion be stabilized. The 2010 BVA Restoration Plan has noted locations for potential streambank stabilization projects. Additional locations have been identified as part of this Watershed Plan and are noted below. Streambank erosion is a natural process that will continue to occur, especially in a developed watershed. The shareholders of the watershed should continue to evaluate the streambank condition and address locations as they are observed. The responsibility of the restoration of streambank erosion is typically the landowners responsibility. The shareholders of the watershed, including private individuals, homeowners associations, watershed groups and the Township should continue to evaluate the all stream channels and look to develop partnerships to correct the problems as they arise. Grant opportunities should be evaluated for funding options.

Recommended streambank stabilization projects include:

A. Shamona Creek Main Stem. (Parcel 33-3-89 Greenbriar Open

Space)

As referenced in the 2010 BVA Restoration Report, Impacted Stream Segment #100 is a severely eroded streambank. This segment is located on the lower portion of the Shamona Creek main stem, approximately 600 feet south from the intersection of Dowlin Forge Road and Fillman Road. The property is owned by the Greenbriar Civic Association and is a 17.2-acre wooded open space area. The length of the erosion is approximately 230-feet long and the near vertical eroded streambanks range are about 12 to 15 feet in height. The erosion is occuring on the east side of the channel prior to a channel direction change to the west. The resident located upslope of this area has completed a streambank stabilization project utilizing large rock material and the Township has completed numerous streambank stabilization projects directly downslope of this area. The downslope projects were completed utilizing hard armor / rip-rap.


The channel slope ranges from one (1) to three (3) percent in this area. The area surrounding the channel is mature woodlands with a significant overstory. The erosion has caused trees along the stream channel to topple. The cause of the erosion within this area can be attributed to the following:

Significant flows at the lower reach of the main stem of the Shamona Creek.

Channel alignment and hydraulic geometry of the channel Recommendations: Due to the continuing erosion and tree impacts along this stream reach, the stabilization of this segment is classified as a high priority project. Based upon the high flows (estimated at approximately 2000 cfs for the 100-year storm event) and the existing overstory, it is recommended that hard armor practices be utilized for this streambank protection project.

Final design considerations must include the following:

o Due to the steep embankments, the side slope may need to be cut back to ensure the riprap is stable. Alternately, a gabion basket or reno mattress system may be an option.

o Undermining or scouring is a potential issue to address in this application. Low level bank protection and deflectors should be incorporated into the final design.

o Vegetive plantings such as live stakes may be feasible and is desireable above the hard armoring of the stream channel. The height of the rock placement should match and / or exceed the height of the streambanks on the opposite side of the channel. Above this rock, a bench can be installed and a more moderate slope can be established. Vegetative plantings can be installed at this location to stabilize the embankment. Plant material must be selected based upon the evaluation of the existing overstory of trees and the soil conditions.

The project will require a PADEP General Permit #3 and depending on the construction equipment, a temporary stream crossing is anticipated to be needed to access the east side of the creek.


Photo 1: Downstream view of severly eroded streambank.

Photo2: Upstream view of eroded bank and down tree


B. Eagleview Corporate Center (Eagleview Lots 59 and 60)

The 2010 BVA Restoration Report has listed Impacted Stream Segment #73-74 as a high priority project. This segment is located upslope of the Eagleview Boulevard Stormwater Management Basin A and is approximately 440 linear feet in length. The BVA Report indicates the stream channel has eroded banks in heights of three (3) to four (4) feet. Based upon the existing vegetation and condition of the surrounding land, the BVA recommends that vegetative stabilization practice can be successfully implemented in this area (live stakes, willow whips, and brush mattresses). Based upon site observations, the following were noted:

The stream in this area is meandering due to the mix cover of forested

areas with an established root base to a mixed open scrub grass and brush fields. The resulting effect from the ground surface cover changes through the area is varying degrees of streambank erosion in specific areas as the stream moves to find the path of least resistance.

In addition to the eroded area noted in the BVA Report, similar, but lower

in height eroded streambanks were observed but were generally re-vegetating with the local grasses.

Two stormwater management channels were observed on Lot 60. These

channels collect and convey stormwater runoff from the upslope parking lot improvements and due to the high outlet velocity, erosion is occurring within the channels.


Photo 1. Looking downstream from storm sewer toward Eagleview Boulevard Basin A on Lot 60.

Photo 2. Eroded stormwater channel from Photo 1.

Recommendations. The streambank erosion located in the Shamona Creek main stem as referenced in the BVA Report (Segment #73-74) and the stormwater conveyance channel erosion are significant contributors to the sediment loads within the watershed and should be addressed. The eroded streambanks and stormwater channels in this area are candidates for vegetative stabilization methods including the use of live stakes, willow strips and brush mattresses. The combination of the plantings, existing vegetation and available sunlight should allow for quick restoration. The areas where erosion is more extensive, a mix of plantings supplemented by coir logs or fascines should be considered. The use vegetative methods will minimize the impacts by construction equipment to the natural floodplain area. Lot 60 of the Eagleview Corporate Park is currently vacant but the owner of the lot has recently submitted a Land Development Plan for the construction of a four-story 85,000 square foot office building. The areas of erosion are proposed to be developed therefore the current channels will be removed. If development of this lot is does not occur at this time, it is recommended that erosion controls and water quality controls be implemented to minimize the erosion and improve water quality of the runoff discharging from the parking areas. A vegetated channel with step pool design could be a cost effective improvement.


C. Shamona Creek Park

The main stem of Shamona Creek parallels Dowlin Forge Road within the Shamona Creek Park for a distance in excess of 2,800-feet. The stream channel is relatively straight with the exception of the crossing of Dowlin Forge Road at the park entrance and the channel has relatively modest grade changes. The width is significant compared to elsewhere within the watershed ranging from 15-feet to 30-feet. The heights of the streambanks range from 2-feet to 4-feet. There is significant tree overstory along the creek on both sides consisting of large and small trees. At various areas along the creek within the park, there are minor areas of streambank erosion. The segments of erosion range from 10-feet in length to 30 to 40-feet. The eroded banks are only a few feet high but undermining of trees located on the streambanks is beginning to occur. Recommendation: In order to minimize the loss of trees and addition of sediment load into the watershed, this streambank erosion should be addressed. Based upon the wide stream channel, modest grades and a low velocity, a combination of coir logs and facines may be a feasible method to address this erosion. These methods would minimize the need for large construction items to access the site which would minimize brush and tree removal along the stream corridor. At the areas where there are modest changes in direction, the placement of rock in the stream corridor should be considered to direct the flow away from the embankments. Options include rock vanes and J-hooks.

D. Martin Memorial Park

Martin Memorial Park is a 15-acre parcel with access off of Laurel Moors Drive and Charles Drive (approximately 900-feet downstream from Deep Willow Drive). The park consists of a parking lot, active recreation fields, a tot lot, a basketball area and passive recreation areas. The Unnamed Tributary to Shamona Creek #2 traverses the center of the park. A small pedestrian wood bridge connects the parking area and the park land. The stream channel varies in width but is generally 3 to 6-feet wide. The streambank height is approximately 1 to 3-feet. Within the park area, the channel slope ranges from 1 to 3-percent. The alignment of the channel can be classified as meandering.


The park is owned and maintained by Uwchlan Township. A portion of the area adjacent to the stream channel is mowed up to the streambank. The stream is an integral part of the park and it is mowed to maintain access for the park users. At varies stream bends within the parkland, minor areas of erosion have begun to occur. Recommendation: Based upon the high visibility of the stream channel within the park, it is recommended that consideration to implementing a combination streambank stabilization project / public education outreach project. Based upon the heights of the stream embankments, the relative low flow compared to the main stem of the Shamona Creek, streambank stabilization can be accomplished via coir log and / or fascines. Work can be completed for relatively low cost and informational signs can be installed adjacent to the project to educate the users of the park of the work completed.

Photo 1. View of streambank erosion looking downstream

within park adjacent to ball fields.


E. Stream encroachments

The Pennsylvania Department of Transportation (PennDOT) inspects all Uwchlan Townships bridges biannually. Bridge inspection reports are prepared by PennDOT and supplied to the Township. Uwchlan Townships Public Works Department also inspects the bridges and culverts before and after major rainfall events to ensure they are not blocked and to assess any damage that may have occurred. Based upon review of the PennDOT inspection reports and inspections of the structures, a variety of minor issues were noted at structures that can contribute to water quality issues. Bridge / culverts are often designed so the stream channel is constricted at the structure. This constriction often creates erosion and scour at the abutments. In addition, the constricted waterways often results in gravel bar deposits within the culvert. This erosion and scour jeopardizes the structural stability of the bridges / culverts and contributes to the sediment loads within the watershed. The gravel bar deposits reduce the flood carrying capacity of the bridge / culvert and if not maintained can be washed out into the watershed during a large storm event. The issues and recommendations for the stream encroachments include the following:

(1) Encroachment #4 Kingston Lane.

Shamona Creek Main Stem - Dowlin Forge Road adjacent to Kingston Lane. Structure: 1942 reinforced concrete T-beam bridge

Issues noted:

Scour at upstream end of bridge, along stone wall adjacent to structure and at downstream side of structure.

Streambank erosion on downstream side of bridge. Recommendations:

Install clean rock protection at scour locations. Install rip-rap protection along streambank on downstream end.

Work will require a PA DEP General Permit-11 to complete


(2) Encroachment #3 Shamona Creek Park Shamona Creek Main Stem - Dowlin Forge Road adjacent to Shamona Creek Park entrance. Structure: 1965 non-composite pre-stressed adjacent box beam bridge

Issues noted:

Scour along southern abutment wall. Gravel bar accumulation along northern abutment.

Recommendations:

Install clean rock protection at scour location. Remove gravel bar under bridge.

Work will require a PA DEP General Permit-11 to complete

(3) Encroachment #2 Crooked Bridge

Shamona Creek Main Stem - Dowlin Forge Road adjacent to 1200 Dowlin Forge Road (Crooked Bridge). Structure: 1907 Brick and Stone Masonry Deck Arch bridge Issues noted:

Scour at upstream end of bridge approximately 30-feet long by 8-feet high.

Recommendations:

Install clean rock protection at scour locations. Work will require a PA DEP General Permit-11.


7.4.2 Land Use / Land Cover Improvement Projects

The following land uses improvements are recommended to enhance water quality within the Shamona Creek watershed.

A. Happy Days Farm Parcel 33-4-28.1, 28, 27.1, 29

Happy Days Farm is located at the headwaters of the Shamona Creek watershed. The farm is currently owned by Nelson Realty Trust of Malvern PA and is approximately 246-acres. 84-acreas of the tract is located within the Shamona Creek watershed and the remainder is located within the Pickering Creek watershed. The parcel is bound between the Pennsylvania Turnpike Interchange, Route 100-Pottstown Pike and Sheree Boulevard. The farm is currently operated by a tenant. Numerous development plans for this parcel has been submitted to Uwchlan Township within the last twenty years but no projects have been constructed. No immediate plans are anticipated for the development of this parcel. To the best of our knowledge, this agricultural use does not have an approved Natural Resource Conservation Service (NRCS) Conservation Plan. Agricultural uses are generally significant contributors to sediment loads within watersheds. Recommendation. In order to improve water quality within the Shamona Creek watershed, it is recommended that the tenant farmer and / or the owner of the lots should be encouraged to develop an agricultural conservation plan and an agricultural erosion and sedimentation control plan for the operation of the farm. Pennsylvanias Chapter 102 (Erosion and Sediment Control and Stormwater Management) Regulations approved on November 19, 2010, require all farms to develop and implement a written plan to reduce erosion when plowing and tilling (includes no-till cropping) and Animal Heavy Use Areas (AHUA) disturbing more than 5,000 square feet. Under Chapter 102, all agricultural plowing and tilling and AHUAs are required to implement agricultural Best Management Practices (BMPs). The Pennsylvania NRCS and the Chester County Conservation District provides local farmers resources to develop a conservation plan. Certified Conservation Planner are available to meet with farmers to establish long and short term


goals and objectives while developing the applicable conservation plan to address the cropping system, livestock, nutrient and pest management.

B. Township Park Land. Shamona Creek Park & Martin Memorial

Park.

Shamona Creek Park is an approximately 23-acre parcel abutting Dowlin Forge Road and Peck Road. Martin Memorial Park is a 15-acre parcel with access off of Laurel Moors Drive and Charles Drive. The main stem of Shamona Creek and the Unnamed Tributary to Shamona Creek #2 traverses Shamona Creek Park and only the unnamed tributary traverses Martin Memorial Park. Both parks have active recreation fields, tot lot areas and passive recreation areas. The parks are maintained by the Township Parks Department. Based upon site investigations, it was observed that significant portions of the park lands are manicured lawn areas. Within Martin Memorial Park, significant areas adjacent in the field areas are mowed up to the stream banks.

Recommendations. It is recommended that the Township complete a comprehensive analysis of the park lands and develop a ground cover management plan for the Township owned lands. Within both parks, portions of the mowed lawn areas can be modified to a meadow with minimal impact to the existing use of the park area. These meadow areas, if properly implemented, can provide water quality improvements. The ground cover management plan should address the required maintenance for the meadow areas which may include bi-annual mowing. A riparian buffer can be implemented around the stream within Martin Memorial Park. In order to provide access to the stream for the users

shamona creek, pennsylvania watershed study and improvement recommendations, 2013. by gannett...

Documents

shamona creek watersheds

watershed information

watershed description

watershed classifications

watershed studies

restoration plan

brandywine valley association

special thanks