post construction stormwater management report

POST CONSTRUCTION STORMWATER MANAGEMENT REPORT

for

Chatham Financial Kennett Township

Chester County, Pennsylvania

December 20, 2016

D.L. Howell Job# 2731

Prepared for:

Chatham Financial 235 Whitehorse Lane

Kennett Square, PA 19348

Prepared by:

D.L. HOWELL & ASSOCIATES, INC. 1250 Wrights Lane, West Chester, PA 19380

Phone: 6109189002 Fax: 6109189003

Chatham Financial Stormwater Management Report Kennett Township, Chester County Page i

TABLE OF CONTENTS Section Page 1.0 INTRODUCTION .................................................................................................................... 1 1.1 Land Use/Watershed................................................................................................... 1 1.2 Site Soils ....................................................................................................................... 3 1.3 Soils Limitations ....................................................................................................... 34 2.0 RUNOFF MANAGEMENT .................................................................................................... 5 3.0 NPDES STORMWATER COMPLIANCE OVERVIEW ..................................................... 56 4.0 CONCLUSION......................................................................................................................... 7 LIST OF FIGURES Figure 11 Site Location Map ........................................................................................... 2 Table 31 NPDES Compliance Chart ............................................................................. 6 APPENDICES Appendix A NPDES 5Year Infiltration Requirement Calculations Appendix B Kennett Township Post Development Flow Reduction Summary Appendix C SCS Method Runoff Curve Numbers (CN) Calculations

Appendix D Hydraflow Hydrograph Reports Appendix E Stormwater Conveyance Calculations Appendix F NRCS Soils Report Appendix G Infiltration Report Appendix H Dewatering Calculations

Chatham Financial Stormwater Management Report Kennett Township, Chester County Page 1

1.0 INTRODUCTION This Stormwater Management Report presents the temporary and permanent control measures/facilities required to support construction activities for the Chatham Financial Project. The 15.256 +/ acre tract is located in Kennett Township (Figure 11). The property is bounded to the north by business parks, to the south and west by commercial/industrial properties and to the east by McFarlan Road. The proposed land development consists of constructing a parking lot expansion. The expansion consists of 161 additional parking spaces. 1.1 LAND USE/WATERSHED The existing land dating back 5 and 50 years ago was categorized as mostly meadow. The site’s topography slopes moderately towards an existing culvert that runs under a driveway associated with a commercial property located south of the property. The property drains to an UNT to the East Branch of the Red Clay Creek. Per Pennsylvania Department of Environmental Protection, 25 Pa. Code, 93.9g “Water Quality Standards” the watershed is classified as Trout Stocking (TSF).

Figure Number: FIGURE 1-1

Title:SITE LOCATION MAP

Source:United States Department of the Interior Geological Survey7.5 Minute Series (Topographic) MapKennett Square, Pennsylvania Quadrangle

Chatham FinancialKennettTownship

Chester CountyPennsylvania

SITE LOCATION


1.2 SITE SOILS Soils information is provided by Penn State College of Agriculture Cooperative Extension, with support from the Natural Resources Conservation Service, United States Department of Agriculture and their Web Soil Survey. Soils attribute data is served from the websoilsurvey.nrcs.usda.gov. All of the below mentioned soils are further evaluated in Appendix F and have been plotted on the Existing Conditions Plan and Erosion and Sedimentation Control Plan. GdB Gladstone gravelly loam, 3 to 8 percent slopes 1.3 SOIL LIMITATIONS: Redoximorphic features were encountered in a few locations during infiltration testing. D.L. Howell has taken into consideration these known soil limitations when designing the infiltration BMPs for the project. The stormwater infiltration facilities have been set a minimum of 2 feet higher than any prohibitive soil limitation elevations witnessed during infiltration testing and adequate infiltration results have been achieved at the adjusted elevations. If during construction, any other unknown soil limitation (i.e. bedrock or high water) is discovered the contractor is responsible for immediately contacting the site geotechnical engineer, design engineer, conservation district and the township engineer for an appropriate solution. The site design drawings contain a pumped water filter bag detail which should be utilized if any excavations need to be dewatered due to high groundwater or excessive rainfall. Geologic formations/soil conditions that may have the potential to cause pollution: Furthermore, there are no known geologic formations or soil conditions that have the potential to cause pollution during earth disturbance activities. If during construction, an unknown geologic formation or soil condition is discovered the contractor is responsible for immediately contacting the Chester County Conservation District and the design engineer.

General Soil Limitations and Resolutions:

Acid soil types: pH lower than 5.5

Soil tests should be taken to determine the actual soil ph reaction. A ph of 5.5 should be achieved to resolve this limitation the soil ph should be adjusted by applying lime rates in accordance with the Penn State Agronomy Guide and the recommendations from a reputable laboratory.

Wet soil types

To resolve this limitation vegetative species that are tolerant to wet conditions should be selected for landscaping.

Poor topsoil


Soil should be imported from other areas on site. The Chester County Conservation District must approve any deviation from the E&SC sequence.

Wet soil types / high water table during excavation activities

Water to be pumped to a dewatering structure, see detail

Poor suitability for winter grading / frost action

Adequate compaction of soil is required for the embankments, pipe backfill, road construction and the building pads. If adequate compaction cannot be achieved due to frost action or wet soil type, either soil should be imported from other areas on site or construction of these facilities should not be worked on during periods prone to frost. The Chester County Conservation District must approve any deviation from the E&SC sequence.

Permeable soil for embankment construction

Soil should be imported from other areas on site. The Chester County Conservation District must approve any deviation from the E&SC sequence.

Poorly suited as sources of topsoil

Identifying and resolving characteristics, that render soil types poorly suited as topsoil.

Erodible soil

Types exhibiting k values greater than 0.36 or plasticity index values lower than 10, limit vegetative stabilization of channels. Resolutions: temporary channel lining, providing permanent channel lining, decreasing channel grade, increasing channel width, selection vegetative with greater retardance, selecting permanent linings other than grasses, and implementing combination of these and other methods.

Soils susceptible to sinkhole formation

Locate facilities, such as sediment basins or traps or stormwater detention or retention basins, on other soil types. Line reservoir areas with impermeable linings, limiting standing water depths, limiting retention times and implementing combinations of these and/or other methods.


2.0 RUNOFF MANAGEMENT The purpose of the stormwater management design is to quantify and control stormwater runoff generated by the modifications of the ground surface conditions to the site (i.e. parking lot). Postdevelopment stormwater management is achieved at the site through two (2) underground infiltration facilities strategically placed throughout the site to control runoff. There is also a rain garden located just south of the proposed parking lot to capture runoff from lawn area to further reduce peak flow discharge, especially during the 2year storm. The majority of the proposed development is controlled by the underground facilities and rain garden, while a small area of lawn will flow off the site to the south uncontrolled. The infiltration beds have been designed utilizing the Soil Conservation Service (SCS) method and Kennett Township regulations (See Appendix D, Standard Worksheets and Design Calculations attached to this report.). These systems are designed to provide an overall reduction in the postdeveloped runoff for the 10year, 25year, 50year, and 100year, 24hour storm event to the predevelopment runoff rates for the equivalent storm events and a reduction for the 2Year to the 1year predevelopment rate, and 5year storm to the 2year predevelopment rate. A stormwater conveyance system will be utilized to convey runoff from the proposed improvements to the proposed stormwater facilities. The stormwater conveyance system will be designed to convey flows up to the 100year storm event. Flows to the pipes were modeled using the Universal Rational Method and the pipes sized using Manning’s Method and Hydraulic Grade Line calculations which are provided in Appendix E. The infiltration beds have been designed and sized to fully infiltrate the increase in volume, pre to postdevelopment for the 5year storm as required by Kennett Township’s regulations. 3.0 NPDES STORMWATER COMPLIANCE As stated above, the infiltration facilities have been designed and sized to fully infiltrate the 5year increase in volume; therefore the NPDES Phase II infiltration requirement, which requires infiltration of the 2year increase, has been met. Furthermore, as described above, the infiltration beds have been designed to incorporate Pennsylvania Department of Environmental Protectionʹs infiltration guidelines, as stated in Appendix C of the Pennsylvania Stormwater Best Management Practices Manual dated December 2006. The stormwater management systems have been designed to maximize infiltration best management practice (BMP) technologies and minimize point source discharges. This plan will further act to perform/provide the following:

· Preserve the integrity of stream channels and maintain and protect the physical, biological and chemical qualities of the receiving stream by utilizing several BMPs to handle the increase in runoff and volume prior to reaching the stream.

· Prevent an increase in the rate of stormwater runoff by utilizing BMPs to reduce the peak flow rate of all storm events up to the 100 year to below the equivalent storm in the predeveloped condition.

· Minimize any increase in stormwater runoff volume by utilizing infiltration BMPs which are designed and sized to fully infiltrate the 5year increase in volume.

· Minimize impervious areas by not maximizing the number of parking spaces on the property.


· Maximize the protection of existing drainage features and existing vegetation by capturing stormwater runoff from the proposed impervious areas and then conveying the flow to stormwater BMPs facilities prior to any release to the existing UNT, thereby protecting it from any sediment.

· Minimize land clearing and grading by designing the parking lot to best match existing grades to preserve and protect the greatest extent possible of the existing vegetation;

· Minimize soil compaction by specifying the installation of orange construction fencing to protect the areas of the proposed infiltration BMPs.

· Utilize other structural or nonstructural BMPs that prevent or minimize changes in stormwater runoff. The structural BMPs are infiltration beds, water quality inlets, vegetated swales, and a rain garden while the nonstructural BMP is landscape restoration.

D.L. Howell & Associates, Inc. has designed Best management Practices (BMP’s) consistent with Chapter 6 of the PA Stormwater Best Management Practices Manual within the stormwater collection and conveyance system in addition to infiltrating the net increase in volume from pre to postdevelopment for the 5year storm event. Mitigating Thermal Impacts: The potential thermal impacts to surface waters are mitigated by the proposed stormwater management system. The BMP facilities are designed to infiltrate volumes greater than the “first flush” of a storm event. It is this “first flush” that carries the highest thermal impact therefore through various infiltration methods, the BMPs mitigate any thermal impacts to the stream by allowing infiltrated runoff to cool prior to reaching surface waters.

Table 3.1

NPDES Compliance Analysis

Drainage Area: L.O.D.

Preconstruction

Post Construction

Net Change

Design storm frequency: 2yr/24 hr Rainfall amount: 3.2"

Impervious area (acres) 0.00 1.41 +1.41

Volume of stormwater runoff acrefeet or cubic feet without planned stormwater BMPs

2,891 18,702 +15,811

Volume of stormwater runoff acrefeet or cubic feet with planned stormwater BMPs

17,573 1,762

Stormwater peak discharge rate for the design frequency storm (cubic feet per second)

0.686 0.141 0.545


4.0 CONCLUSIONS D.L. Howell & Associates, Inc. has completed a stormwater engineering design for the proposed project in Kennett Township, Chester County, Pennsylvania. Using sitespecific topography, soils, land cover, hydrologic data, and Township Ordinances, D.L. Howell & Associates, Inc. designed the stormwater management system for the proposed facilities. The objective of the stormwater design was to develop sitespecific stormwater management structures that reduce postdevelopment runoff to predevelopment runoff rates and provide volumetric storage per Township and PADEP NPDES Phase II requirements. Postdevelopment stormwater management is achieved through a stormwater collection system consisting of curbed inlets, swales, stormwater infiltration beds and a rain garden. The postdevelopment flows are summarized in Appendix B.

Chatham Financial Stormwater Management Report Kennett Township, Chester County Page A

APPENDIX A

5YEAR INFILTRATION REQUIREMENT CALCULATIONS

Pennsylvania Stormwater Best Management Practices Manual Chapter 8

PROJECT:Drainage Area:5-Year Rainfall: 4.2 in

Total Site Area: 15.256 acresProtected Site Area: 12.922 acresManaged Area: 2.334 acres

Existing Conditions

Cover Type/Conditions

Soil Type

Area (sf) Area (ac) CN S la (0.2*S) Q Runoff1 (in)Runoff

Volume2 (ft3)

Woodland A 0 25Meadow A 0 30Impervious A 0 98

Woodland B 55Meadow B 101,683 2.33 58 7.2414 1.4483 0.76 6,421Meadow (20% Exist. Iimp.) B 58Impervious (80% Exist.) B 84

Woodland C 70Meadow C 71Impervious C 98

Woodland D 0 77Meadow D 0 78Impervious D 0 98

TOTAL: 101,683 2.33 6,421

Developed Conditions

Cover Type/Conditions

Soil Type

Area (sf) Area (ac) CN S la (0.2*S) Q Runoff1 (in)Runoff

Volume2 (ft3)Lawn C 40,064 0.92 74 3.5135 0.7027 1.74 5,825Impervious N/A 61,619 1.41 98 0.2041 0.0408 3.96 20,358

TOTAL: 101,683 2.33 26,183

5-Year Volume Increase (ft3):

1. Runoff (in) = Q = (P - 0.2S)2 / (P + 08.S)P = 2-Year Rainfall (in)S = (1000/CN) - 10

2. Runoff Volume (CF) = Q x Area x 1/12Q = Runoff (in)Area = Land Use Area (Sq. Ft)

Note: Runoff Volume must be calculated for EACH land use type/condition and HSGI.The use of a weighted CN value for volume calculations is not acceptable.

WORKSHEET 4 . CHANGE IN RUNOFF VOLUME FOR 5-YR STORM EVENT

Chatham Financial

Limit of Disturbance (LOD)

19,762

5-Year Volume Increase = Developed Conditions Runoff Volume - Existing Conditions Runoff Volume

363-0300-002 / December 30, 2006

PROJECT:5-Year Rainfall: 4.2 in

BMP:

Cover Type Soil Type Area (sf) Area (ac) CN S la (0.2*S) Q Runoff1

(in)Runoff Volume2

(ft3)Impervious N/A 27,435 0.63 98 0.2041 0.0408 3.96 9,064Lawn C 18,849 0.43 74 3.5135 0.7027 1.74 2,740

TOTAL: 46,284 1.06 11,805

BMP:

Cover Type Soil Type Area (sf) Area (ac) CN S la (0.2*S) Q Runoff1

(in)Runoff Volume2

(ft3)Impervious N/A 34,134 0.78 98 0.2041 0.0408 3.96 11,277Lawn C 9,763 0.22 74 3.5135 0.7027 1.74 1,419

TOTAL: 43,897 1.01 12,697

RUNOFF VOLUME FOR 5-YR STORM EVENT TO SELECTED BMPS

Chatham Financial

Bed 1

Bed 2

3930-PM-WM0035 / Rev 5/2007

Pipe Material HDPEPipe Size 30 in. Void Ratio 0.40Pipe Size ID 2.50 ft. Void Ratio 0.40Pipe Size OD 2.93 ft.

Pipe Spacing 2.00 ft. Bed Area 7,600Ext. Width 4.00 ft. Bed Area 0.17Number 15.00 pipes

Pipe Length 81 ft. Pipe Width 71.88Bed Length 95.00 ft. Bed Width 80.00Bottom Elev. 375 ELEV (ft.)

Basin Slope 0.000 ft./ft.

d/D Depth Elevation A/Afull Length A1 A2 Stone Stone Stone Total TotalDownstream Upstream Indiv. Total Downstream Upstream Below S.L. Above S.L. Total

(ft.) (ft.) (sf) (lf) (sf) (sf) (cf) (cf) (cf) (cf) (cf) (cf) (cf) (cf) (ac-ft)

Stone 0 375.00 0.000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0 0.000

ft.

PROJECT - CHATHAM FINANCIAL

KENNETT TOWNSHIP, CHESTER COUNTYJOB NUMBER - 2731

REVISION - 0 12/14/2016BY: CMD CHKD BY:

UNDERGROUND BASIN DESIGN (UG 1)

above springline

below springline

S.F.

ACRES

ft.

STORAGE TABLEAREA VOLUME

Long Pipe(s) Cross Pipe(s)

Stone 0 375.00 0.000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0 0.000Stone 0.25 375.25 0.000 81.00 0.00 0.00 0.00 0.00 0.00 0.00 760.00 0.00 760.00 760 0.017Stone 0.5 375.50 0.000 81.00 0.00 0.00 0.00 0.00 0.00 0.00 1,520.00 0.00 1,520.00 1520 0.0350.10 0.75 375.75 0.052 81.00 0.26 0.26 20.68 310.13 18.35 18.35 2,135.85 0.00 2,135.85 2483 0.0570.20 1 376.00 0.142 81.00 0.70 0.70 56.46 846.90 50.10 50.10 2,646.37 0.00 2,646.37 3593 0.0820.30 1.25 376.25 0.252 81.00 1.24 1.24 100.20 1,502.96 88.91 88.91 3,101.45 0.00 3,101.45 4782 0.1100.40 1.5 376.50 0.373 81.00 1.83 1.83 148.31 2,224.61 131.60 131.60 3,526.04 0.00 3,526.04 6014 0.1380.50 1.75 376.75 0.500 81.00 2.45 2.45 198.80 2,982.06 176.41 176.41 3,933.99 0.00 3,933.99 7269 0.1670.60 2 377.00 0.625 81.00 3.07 3.07 248.50 3,727.57 220.51 220.51 3,933.99 316.90 4,250.89 8419 0.1930.70 2.25 377.25 0.747 81.00 3.67 3.67 297.01 4,455.19 263.55 263.55 3,933.99 738.72 4,672.71 9655 0.2220.80 2.5 377.50 0.856 81.00 4.20 4.20 340.35 5,105.28 302.01 302.01 3,933.99 1,196.57 5,130.56 10840 0.2490.90 2.75 377.75 0.948 81.00 4.65 4.65 376.93 5,653.98 334.47 334.47 3,933.99 1,701.54 5,635.53 11958 0.2751.00 3 378.00 1.000 81.00 4.91 4.91 397.61 5,964.11 352.82 352.82 3,933.99 2,317.40 6,251.39 12921 0.297

Stone 3.25 378.25 1.000 81.00 4.91 4.91 397.61 5,964.11 352.82 352.82 3,933.99 3,077.40 7,011.39 13681 0.314Stone 3.5 378.50 1.000 81.00 4.91 4.91 397.61 5,964.11 352.82 352.82 3,933.99 3,837.40 7,771.39 14441 0.332

Totals 14441 0.332

Note: Stone Volume Equation Utilizing Void Ratio specified above equal toTotal Bed Volume (Bed Length x Bed Width) - Pipe Area based on O.D. (Long Pipes + Cross Pipes) X Void Ratio

NOTES:

Pipe Material HDPEPipe Size 36 in. Void Ratio 0.40Pipe Size ID 3.00 ft. Void Ratio 0.40Pipe Size OD 3.48 ft.

Pipe Spacing 2.00 ft. Bed Area 6,250Ext. Width 2.50 ft. Bed Area 0.14Number 4.00 pipes

Pipe Length 238 ft. Pipe Width 19.90Bed Length 250.00 ft. Bed Width 25.00Bottom Elev. 373.5 ELEV (ft.)

Basin Slope 0.000 ft./ft.

d/D Depth Elevation A/Afull Length A1 A2 Stone Stone Stone Total TotalDownstream Upstream Indiv. Total Downstream Upstream Below S.L. Above S.L. Total

(ft.) (ft.) (sf) (lf) (sf) (sf) (cf) (cf) (cf) (cf) (cf) (cf) (cf) (cf) (ac-ft)

Stone 0 373.50 0.000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0 0.000

S.F.

ACRES

ft.

BY: CMD CHKD BY:

UNDERGROUND BASIN DESIGN (UG 2)

above springline

below springline

PROJECT - CHATHAM FINANCIAL

KENNETT TOWNSHIP, CHESTER COUNTYJOB NUMBER - 2731

REVISION - 0 12/14/2016

ft.

STORAGE TABLEAREA VOLUME

Long Pipe(s) Cross Pipe(s)

Stone 0 373.50 0.000 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0 0.000Stone 0.25 373.75 0.000 238.00 0.00 0.00 0.00 0.00 0.00 0.00 625.00 0.00 625.00 625 0.014Stone 0.5 374.00 0.000 238.00 0.00 0.00 0.00 0.00 0.00 0.00 1,250.00 0.00 1,250.00 1250 0.0290.10 0.8 374.30 0.052 238.00 0.37 0.37 87.48 349.92 7.31 7.31 1,852.18 0.00 1,852.18 2217 0.0510.20 1.1 374.60 0.142 238.00 1.00 1.00 238.89 955.56 19.97 19.97 2,346.34 0.00 2,346.34 3342 0.0770.30 1.4 374.90 0.252 238.00 1.78 1.78 423.95 1,695.78 35.45 35.45 2,783.64 0.00 2,783.64 4550 0.1040.40 1.7 375.20 0.373 238.00 2.64 2.64 627.51 2,510.02 52.47 52.47 3,189.67 0.00 3,189.67 5805 0.1330.50 2 375.50 0.500 238.00 3.53 3.53 841.16 3,364.64 70.33 70.33 3,578.65 0.00 3,578.65 7084 0.1630.60 2.3 375.80 0.625 238.00 4.42 4.42 1,051.45 4,205.80 87.92 87.92 3,578.65 356.92 3,935.56 8317 0.1910.70 2.6 376.10 0.747 238.00 5.28 5.28 1,256.69 5,026.78 105.08 105.08 3,578.65 760.11 4,338.75 9576 0.2200.80 2.9 376.40 0.856 238.00 6.05 6.05 1,440.07 5,760.27 120.41 120.41 3,578.65 1,200.25 4,778.90 10780 0.2470.90 3.2 376.70 0.948 238.00 6.70 6.70 1,594.84 6,379.36 133.35 133.35 3,578.65 1,688.72 5,267.37 11913 0.2731.00 3.5 377.00 1.000 238.00 7.07 7.07 1,682.32 6,729.29 140.66 140.66 3,578.65 2,290.90 5,869.55 12880 0.296

Stone 3.75 377.25 1.000 238.00 7.07 7.07 1,682.32 6,729.29 140.66 140.66 3,578.65 2,915.90 6,494.55 13505 0.310Stone 4 377.50 1.000 238.00 7.07 7.07 1,682.32 6,729.29 140.66 140.66 3,578.65 3,540.90 7,119.55 14130 0.324

Totals 14130 0.324

Note: Stone Volume Equation Utilizing Void Ratio specified above equal toTotal Bed Volume (Bed Length x Bed Width) - Pipe Area based on O.D. (Long Pipes + Cross Pipes) X Void Ratio

NOTES:

BMP LOADING RATIOBMP LOADING RATIOCALCULATION WORKSHEET

DATE: 12/21/2016

REV: 0

BY: CMD

JOB NO.: 2731 PROJECT: Chatham Financial TOWNSHIP: Kennett

Drainage Area: Post to Bed 1

1.06 AC 0.63 AC

0.13 AC 0.13 AC

Required Infiltration Surface Area

Total Loading Surface Area = Impervious Loading Area =

Total Drainage Area: Impervious Area:

0.13 AC 0.13 AC

COMMENT0.170.000.00


BMP Area (acres)BMP/Infiltation Areas:

Subsurface Infiltration Bed

0.000.000.000.000.000.17Total BMP/Infiltation Areas Provided:

6.08 :1 3.61 :1Total Loading Ratio = Impervious Loading Ratio =

BMP LOADING RATIOBMP LOADING RATIOCALCULATION WORKSHEET

DATE: 12/21/2016

REV: 0

BY: CMD

JOB NO.: 2731 PROJECT: Chatham Financial TOWNSHIP: Kennett

Drainage Area: Post to Bed 2

1.01 AC 0.78 AC

0.13 AC 0.16 AC

Total Drainage Area: Impervious Area:

Required Infiltration Surface Area

Total Loading Surface Area = Impervious Loading Area =0.13 AC 0.16 AC

COMMENT0.140.000.00


BMP Area (acres)BMP/Infiltation Areas:

Subsurface Infiltration Bed

0.000.000.000.000.000.14Total BMP/Infiltation Areas Provided:

7.04 :1 5.44 :1Total Loading Ratio = Impervious Loading Ratio =

Chatham Financial Stormwater Management Report Kennett Township, Chester County Page B

APPENDIX B

KENNETT TOWNSHIP POST DEVELOPMENT

FLOW REDUCTION SUMMARY

Stormwater Summary

DATE: 12/14/2016

Peak Flow Reduction RequirementsWest POI

DATE: 12/14/2016

BY: CMD

JOB NO.: 2731 PROJECT: TOWNSHIP: Kennett

DESCRIPTION: Stormwater Summary

1-year 0.145 cfs Hydrograph 1

1-year 0.089 cfsPre-DevelopedPost-Developed

Chatham Financial






Post-Developed

Post-Developed

Pre-DevelopedPost-Developed

Pre-Developed






Post-Developed

Pre-Developed

Pre-Developed






.

Pre-Developed


Post-Developed

Post Developed 2 Year Flow = 0.141 cfs0.145 cfs

0.237 cfs0.686 cfs

0.390 cfs3.759 cfsPre Developed 10 Year Flow =

Post Developed 10 Year Flow =

Pre Developed 1 Year Flow =

OKPost Developed 5 Year Flow =

OK

Peak Rate Control Requirement (New Development)


OK

3.759 cfs

0.999 cfs5.039 cfs

2.651 cfs6.636 cfsPre Developed 50 Year Flow =


Pre Developed 25 Year Flow = Post Developed 25 Year Flow =

Post Developed 50 Year Flow =

OK

OK

OK

6.834 cfs11.910 cfs

OKPost Developed 100 Year Flow = Pre Developed 100 Year Flow =

Chatham Financial Stormwater Management Report Kennett Township, Chester County Page C

APPENDIX C

SCS METHOD CURVE NUMBER (CN) CALCULATIONS

SOIL CONSERVATION SERVICE

DATE: 12/14/2016

REV: 0

BY: CMD

SOIL CONSERVATION SERVICEHYDROLOGIC DATA FOR WATERSHED

RUNOFF COMPUTATIONS

BY: CMD

JOB NO.: 2731 PROJECT: Chatham Financial TOWNSHIP: KENNETT TOWNSHIP

DESCRIPTION: PRE-DEVELOPMENT

Total Area: 2.45 acres

Hydrological Hydrologic Soil Runoff Area Complex Number CommentSymbol Soil Name Soil Group Land Use Condition Curve Number acres acres

GdB Gladstone B MEADOW Good 58 2.45 141.94

Total Area 2.45 141.94Total Area 2.45 141.94

Weighted Soil 141.94 = 58.0 TIME OF CONCENTRATION - SEE HYDRAFLOW REPORTComplex Number 2.45


DATE: 12/14/2016

REV: 0

BY: CMD


RUNOFF COMPUTATIONS

BY: CMD


DESCRIPTION: POST DEVELOPMENT - Infiltration Bed 1



GdB Gladstone B (Lowered to C) LAWN Good 74 0.43 32.02N/A N/A IMPERVIOUS Good 98 0.63 61.72


Weighted Soil 93.74 = 88.2 TIME OF CONCENTRATION - ASSUME 5 MINUTESComplex Number 1.06


DATE: 12/14/2016

REV: 0

BY: CMD


RUNOFF COMPUTATIONS

BY: CMD


DESCRIPTION: POST DEVELOPMENT - Infiltration Bed 2







DATE: 12/14/2016

REV: 0

BY: CMD


RUNOFF COMPUTATIONS

BY: CMD


DESCRIPTION: POST DEVELOPMENT - Rain Garden 1







DATE: 12/14/2016

REV: 0

BY: CMD


RUNOFF COMPUTATIONS

BY: CMD


DESCRIPTION: POST BYPASS






Chatham Financial Stormwater Management Report Kennett Township, Chester County Page D

APPENDIX D

HYDRAFLOW HYDROGRAPH REPORTS

Hydrograph Summary Report1

Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total HydrographNo. type flow interval Peak volume hyd(s) elevation strge used Description

(origin) (cfs) (min) (min) (cuft) (ft) (cuft)

1 SCS Runoff 0.145 2 726 1,448 ------ ------ ------ PRE-DEV

2 SCS Runoff 0.089 2 718 181 ------ ------ ------ BYPASS

4 SCS Runoff 2.632 2 716 5,347 ------ ------ ------ POST TO BED 1

5 Reservoir 0.000 2 n/a 0 4 376.34 5,347 BED 1 ROUTED


8 Combine 3.029 2 716 6,348 5, 7 ------ ------ BED 1 ROUTED + POST TO BED 2


11 SCS Runoff 0.322 2 718 657 ------ ------ ------ POST TO RAIN GARDEN

12 Reservoir 0.000 2 n/a 0 11 375.23 657 RAIN GARDEN ROUTED

14 Combine 0.089 2 718 181 2, 9, 12, ------ ------ COMBINED

2731 SWM.gpw Return Period: 1 Year Tuesday, 12 / 27 / 2016

Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2016 by Autodesk, Inc. v11

Hydrograph ReportHydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2016 by Autodesk, Inc. v11 Tuesday, 12 / 27 / 2016

Hyd. No. 1

PRE-DEV

Hydrograph type = SCS Runoff Peak discharge = 0.145 cfsStorm frequency = 1 yrs Time to peak = 726 minTime interval = 2 min Hyd. volume = 1,448 cuftDrainage area = 2.450 ac Curve number = 58Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = TR55 Time of conc. (Tc) = 10.80 minTotal precip. = 2.60 in Distribution = Type IIStorm duration = 24 hrs Shape factor = 484

2

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

0.05 0.05

0.10 0.10

0.15 0.15

0.20 0.20

0.25 0.25

0.30 0.30

0.35 0.35

0.40 0.40

0.45 0.45

0.50 0.50

Q (cfs)

Time (min)

PRE-DEVHyd. No. 1 -- 1 Year

Hyd No. 1

TR55 Tc Worksheet3


Hyd. No. 1

PRE-DEV

Description A B C Totals

Sheet FlowManning's n-value = 0.240 0.011 0.011Flow length (ft) = 100.0 0.0 0.0Two-year 24-hr precip. (in) = 3.20 0.00 0.00Land slope (%) = 6.00 0.00 0.00

Travel Time (min) = 9.20 + 0.00 + 0.00 = 9.20

Shallow Concentrated FlowFlow length (ft) = 284.00 0.00 0.00Watercourse slope (%) = 3.52 0.00 0.00Surface description = Unpaved Paved PavedAverage velocity (ft/s) =3.03 0.00 0.00

Travel Time (min) = 1.56 + 0.00 + 0.00 = 1.56

Channel FlowX sectional flow area (sqft) = 0.00 0.00 0.00Wetted perimeter (ft) = 0.00 0.00 0.00Channel slope (%) = 0.00 0.00 0.00Manning's n-value = 0.015 0.015 0.015Velocity (ft/s) =0.00

0.000.00

Flow length (ft) ({0})0.0 0.0 0.0

Travel Time (min) = 0.00 + 0.00 + 0.00 = 0.00

Total Travel Time, Tc .............................................................................. 10.80 min


Hyd. No. 2

BYPASS

Hydrograph type = SCS Runoff Peak discharge = 0.089 cfsStorm frequency = 1 yrs Time to peak = 718 minTime interval = 2 min Hyd. volume = 181 cuftDrainage area = 0.080 ac Curve number = 74Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = User Time of conc. (Tc) = 5.00 minTotal precip. = 2.60 in Distribution = Type IIStorm duration = 24 hrs Shape factor = 484

4

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

0.01 0.01

0.02 0.02

0.03 0.03

0.04 0.04

0.05 0.05

0.06 0.06

0.07 0.07

0.08 0.08

0.09 0.09

0.10 0.10

Q (cfs)

Time (min)

BYPASSHyd. No. 2 -- 1 Year

Hyd No. 2


Hyd. No. 4

POST TO BED 1

Hydrograph type = SCS Runoff Peak discharge = 2.632 cfsStorm frequency = 1 yrs Time to peak = 716 minTime interval = 2 min Hyd. volume = 5,347 cuftDrainage area = 1.060 ac Curve number = 88.2Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = User Time of conc. (Tc) = 5.00 minTotal precip. = 2.60 in Distribution = Type IIStorm duration = 24 hrs Shape factor = 484

5

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

Q (cfs)

Time (min)

POST TO BED 1Hyd. No. 4 -- 1 Year

Hyd No. 4


Hyd. No. 5

BED 1 ROUTED

Hydrograph type = Reservoir Peak discharge = 0.000 cfsStorm frequency = 1 yrs Time to peak = n/aTime interval = 2 min Hyd. volume = 0 cuftInflow hyd. No. = 4 - POST TO BED 1 Max. Elevation = 376.34 ftReservoir name = BED 1 Max. Storage = 5,347 cuft

Storage Indication method used.

6

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

Q (cfs)

Time (min)

BED 1 ROUTEDHyd. No. 5 -- 1 Year

Hyd No. 5 Hyd No. 4 Total storage used = 5,347 cuft

Pond Report 7

Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2016 by Autodesk, Inc. v11 Tuesday, 12 / 27 / 2016

Pond No. 2 - BED 1

Pond DataPond storage is based on user-defined values.

Stage / Storage TableStage (ft) Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft)

0.00 375.00 n/a 0 00.50 375.50 n/a 1,520 1,5203.00 378.00 n/a 11,401 12,9213.50 378.50 n/a 1,520 14,441

Culvert / Orifice Structures Weir Structures

[A] [B] [C] [PrfRsr] [A] [B] [C] [D]

Rise (in) = 15.00 0.00 0.00 0.00

Span (in) = 15.00 0.00 0.00 0.00

No. Barrels = 1 0 0 0Invert El. (ft) = 375.00 0.00 0.00 0.00

Length (ft) = 27.00 0.00 0.00 0.00

Slope (%) = 0.52 0.00 0.00 n/a

N-Value = .013 .013 .013 n/aOrifice Coeff. = 0.60 0.60 0.60 0.60

Multi-Stage = n/a No No No

Crest Len (ft) = 11.00 4.00 0.00 0.00

Crest El. (ft) = 384.86 378.00 0.00 0.00

Weir Coeff. = 3.33 3.33 3.33 3.33Weir Type = 1 Rect --- ---

Multi-Stage = Yes Yes No No

Exfil.(in/hr) = 0.000 (by Wet area)

TW Elev. (ft) = 0.00

Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s).

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00

Stage (ft)

0.00 375.00

1.00 376.00

2.00 377.00

3.00 378.00

4.00 379.00

Elev (ft)

Discharge (cfs)

Stage / Discharge

Total Q


Hyd. No. 7

POST TO BED 2


8

0 120 240 360 480 600 720 840 960 1080 1200 1320

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

Q (cfs)

Time (min)


Hyd No. 7


Hyd. No. 8

BED 1 ROUTED + POST TO BED 2

Hydrograph type = Combine Peak discharge = 3.029 cfsStorm frequency = 1 yrs Time to peak = 716 minTime interval = 2 min Hyd. volume = 6,348 cuftInflow hyds. = 5, 7 Contrib. drain. area = 1.010 ac

9

0 120 240 360 480 600 720 840 960 1080 1200 1320

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

Q (cfs)

Time (min)

BED 1 ROUTED + POST TO BED 2Hyd. No. 8 -- 1 Year

Hyd No. 8 Hyd No. 5 Hyd No. 7


Hyd. No. 9

BED 2 ROUTED

Hydrograph type = Reservoir Peak discharge = 0.000 cfsStorm frequency = 1 yrs Time to peak = n/aTime interval = 2 min Hyd. volume = 0 cuftInflow hyd. No. = 8 - BED 1 ROUTED + POST TO BED 2Max. Elevation = 375.32 ftReservoir name = BED 2 Max. Storage = 6,348 cuft


10

0 120 240 360 480 600 720 840 960 1080 1200 1320

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

Q (cfs)

Time (min)



Pond Report 11


Pond No. 3 - BED 2

Pond DataPond storage is based on user-defined values.


0.00 373.50 n/a 0 00.50 374.00 n/a 1,250 1,2503.50 377.00 n/a 11,630 12,8804.00 377.50 n/a 1,250 14,130


[A] [B] [C] [PrfRsr] [A] [B] [C] [D]

Rise (in) = 15.00 0.00 0.00 0.00

Span (in) = 15.00 0.00 0.00 0.00


Length (ft) = 135.00 0.00 0.00 0.00

Slope (%) = 0.56 0.00 0.00 n/a



Crest Len (ft) = 11.00 2.00 0.00 0.00

Crest El. (ft) = 385.00 376.00 0.00 0.00

Weir Coeff. = 3.33 3.33 3.33 3.33Weir Type = 1 Rect --- ---

Multi-Stage = Yes Yes No No




0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00

Stage (ft)

0.00 373.50

1.00 374.50

2.00 375.50

3.00 376.50

4.00 377.50

Elev (ft)

Discharge (cfs)

Stage / Discharge

Total Q


Hyd. No. 11

POST TO RAIN GARDEN


12

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

0.05 0.05

0.10 0.10

0.15 0.15

0.20 0.20

0.25 0.25

0.30 0.30

0.35 0.35

0.40 0.40

0.45 0.45

0.50 0.50

Q (cfs)

Time (min)

POST TO RAIN GARDENHyd. No. 11 -- 1 Year

Hyd No. 11


Hyd. No. 12

RAIN GARDEN ROUTED

Hydrograph type = Reservoir Peak discharge = 0.000 cfsStorm frequency = 1 yrs Time to peak = n/aTime interval = 2 min Hyd. volume = 0 cuftInflow hyd. No. = 11 - POST TO RAIN GARDENMax. Elevation = 375.23 ftReservoir name = RAIN GARDEN 1 Max. Storage = 657 cuft


13

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

0.05 0.05

0.10 0.10

0.15 0.15

0.20 0.20

0.25 0.25

0.30 0.30

0.35 0.35

0.40 0.40

0.45 0.45

0.50 0.50

Q (cfs)

Time (min)

RAIN GARDEN ROUTEDHyd. No. 12 -- 1 Year

Hyd No. 12 Hyd No. 11 Total storage used = 657 cuft

Pond Report 14


Pond No. 1 - RAIN GARDEN 1

Pond DataContours -User-defined contour areas. Average end area method used for volume calculation. Begining Elevation = 375.00 ft


0.00 375.00 2,648 0 00.50 375.50 3,186 1,459 1,4591.00 376.00 3,787 1,743 3,202


[A] [B] [C] [PrfRsr] [A] [B] [C] [D]

Rise (in) = 4.00 0.00 0.00 0.00

Span (in) = 4.00 0.00 0.00 0.00


Length (ft) = 18.00 0.00 0.00 0.00

Slope (%) = 2.78 0.00 0.00 n/a



Crest Len (ft) = 8.00 0.00 0.00 0.00

Crest El. (ft) = 375.50 0.00 0.00 0.00

Weir Coeff. = 3.33 3.33 3.33 3.33Weir Type = 1 --- --- ---

Multi-Stage = Yes No No No




0.00 0.04 0.08 0.12 0.16 0.20 0.24 0.28 0.32 0.36 0.40

Stage (ft)

0.00 375.00

0.10 375.10

0.20 375.20

0.30 375.30

0.40 375.40

0.50 375.50

0.60 375.60

0.70 375.70

0.80 375.80

0.90 375.90

1.00 376.00

Elev (ft)

Discharge (cfs)

Stage / Discharge

Total Q


Hyd. No. 14

COMBINED

Hydrograph type = Combine Peak discharge = 0.089 cfsStorm frequency = 1 yrs Time to peak = 718 minTime interval = 2 min Hyd. volume = 181 cuftInflow hyds. = 2, 9, 12 Contrib. drain. area = 0.080 ac

15

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

0.01 0.01

0.02 0.02

0.03 0.03

0.04 0.04

0.05 0.05

0.06 0.06

0.07 0.07

0.08 0.08

0.09 0.09

0.10 0.10

Q (cfs)

Time (min)

COMBINEDHyd. No. 14 -- 1 Year

Hyd No. 14 Hyd No. 2 Hyd No. 9 Hyd No. 12










9 Reservoir 0.011 2 1444 74 8 375.82 8,291 BED 2 ROUTED

11 SCS Runoff 0.511 2 718 1,024 ------ ------ ------ POST TO RAIN GARDEN

12 Reservoir 0.000 2 n/a 0 11 375.35 1,024 RAIN GARDEN ROUTED

14 Combine 0.141 2 718 356 2, 9, 12, ------ ------ COMBINED




Hyd. No. 1

PRE-DEV


17

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

0.10 0.10

0.20 0.20

0.30 0.30

0.40 0.40

0.50 0.50

0.60 0.60

0.70 0.70

0.80 0.80

0.90 0.90

1.00 1.00

Q (cfs)

Time (min)


Hyd No. 1


Hyd. No. 2

BYPASS


18

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

0.05 0.05

0.10 0.10

0.15 0.15

0.20 0.20

0.25 0.25

0.30 0.30

0.35 0.35

0.40 0.40

0.45 0.45

0.50 0.50

Q (cfs)

Time (min)


Hyd No. 2


Hyd. No. 4

POST TO BED 1


19

0 120 240 360 480 600 720 840 960 1080 1200 1320

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

Q (cfs)

Time (min)


Hyd No. 4


Hyd. No. 5

BED 1 ROUTED



20

0 120 240 360 480 600 720 840 960 1080 1200 1320

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

Q (cfs)

Time (min)




Hyd. No. 7

POST TO BED 2


21

0 120 240 360 480 600 720 840 960 1080 1200

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

Q (cfs)

Time (min)


Hyd No. 7


Hyd. No. 8



22

0 120 240 360 480 600 720 840 960 1080 1200

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

Q (cfs)

Time (min)




Hyd. No. 9

BED 2 ROUTED

Hydrograph type = Reservoir Peak discharge = 0.011 cfsStorm frequency = 2 yrs Time to peak = 1444 minTime interval = 2 min Hyd. volume = 74 cuftInflow hyd. No. = 8 - BED 1 ROUTED + POST TO BED 2Max. Elevation = 375.82 ftReservoir name = BED 2 Max. Storage = 8,291 cuft


23

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 1680

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

Q (cfs)

Time (min)




Hyd. No. 11

POST TO RAIN GARDEN

Hydrograph type = SCS Runoff Peak discharge = 0.511 cfsStorm frequency = 2 yrs Time to peak = 718 minTime interval = 2 min Hyd. volume = 1,024 cuftDrainage area = 0.290 ac Curve number = 74Basin Slope = 0.0 % Hydraulic length = 0 ftTc method = User Time of conc. (Tc) = 5.00 minTotal precip. = 3.20 in Distribution = Type IIStorm duration = 24 hrs Shape factor = 484

24

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

0.10 0.10

0.20 0.20

0.30 0.30

0.40 0.40

0.50 0.50

0.60 0.60

0.70 0.70

0.80 0.80

0.90 0.90

1.00 1.00

Q (cfs)

Time (min)


Hyd No. 11


Hyd. No. 12

RAIN GARDEN ROUTED

Hydrograph type = Reservoir Peak discharge = 0.000 cfsStorm frequency = 2 yrs Time to peak = n/aTime interval = 2 min Hyd. volume = 0 cuftInflow hyd. No. = 11 - POST TO RAIN GARDENMax. Elevation = 375.35 ftReservoir name = RAIN GARDEN 1 Max. Storage = 1,024 cuft


25

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

0.10 0.10

0.20 0.20

0.30 0.30

0.40 0.40

0.50 0.50

0.60 0.60

0.70 0.70

0.80 0.80

0.90 0.90

1.00 1.00

Q (cfs)

Time (min)




Hyd. No. 14

COMBINED

Hydrograph type = Combine Peak discharge = 0.141 cfsStorm frequency = 2 yrs Time to peak = 718 minTime interval = 2 min Hyd. volume = 356 cuftInflow hyds. = 2, 9, 12 Contrib. drain. area = 0.080 ac

26

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 1680

Q (cfs)

0.00 0.00

0.05 0.05

0.10 0.10

0.15 0.15

0.20 0.20

0.25 0.25

0.30 0.30

0.35 0.35

0.40 0.40

0.45 0.45

0.50 0.50

Q (cfs)

Time (min)












9 Reservoir 0.116 2 904 3,396 8 375.97 8,870 BED 2 ROUTED


12 Reservoir 0.014 2 1102 263 11 375.50 1,468 RAIN GARDEN ROUTED

14 Combine 0.237 2 718 4,133 2, 9, 12, ------ ------ COMBINED




Hyd. No. 1

PRE-DEV


28

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

Q (cfs)

Time (min)


Hyd No. 1


Hyd. No. 2

BYPASS


29

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

0.05 0.05

0.10 0.10

0.15 0.15

0.20 0.20

0.25 0.25

0.30 0.30

0.35 0.35

0.40 0.40

0.45 0.45

0.50 0.50

Q (cfs)

Time (min)


Hyd No. 2


Hyd. No. 4

POST TO BED 1


30

0 120 240 360 480 600 720 840 960 1080 1200 1320

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

5.00 5.00

6.00 6.00

Q (cfs)

Time (min)


Hyd No. 4


Hyd. No. 5

BED 1 ROUTED



31

0 120 240 360 480 600 720 840 960 1080 1200 1320

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

5.00 5.00

6.00 6.00

Q (cfs)

Time (min)




Hyd. No. 7

POST TO BED 2


32

0 120 240 360 480 600 720 840 960 1080 1200

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

5.00 5.00

6.00 6.00

Q (cfs)

Time (min)


Hyd No. 7


Hyd. No. 8



33

0 120 240 360 480 600 720 840 960 1080 1200

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

5.00 5.00

6.00 6.00

Q (cfs)

Time (min)




Hyd. No. 9

BED 2 ROUTED

Hydrograph type = Reservoir Peak discharge = 0.116 cfsStorm frequency = 5 yrs Time to peak = 904 minTime interval = 2 min Hyd. volume = 3,396 cuftInflow hyd. No. = 8 - BED 1 ROUTED + POST TO BED 2Max. Elevation = 375.97 ftReservoir name = BED 2 Max. Storage = 8,870 cuft


34

0 240 480 720 960 1200 1440 1680 1920

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

5.00 5.00

6.00 6.00

Q (cfs)

Time (min)




Hyd. No. 11

POST TO RAIN GARDEN


35

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

0.10 0.10

0.20 0.20

0.30 0.30

0.40 0.40

0.50 0.50

0.60 0.60

0.70 0.70

0.80 0.80

0.90 0.90

1.00 1.00

Q (cfs)

Time (min)


Hyd No. 11


Hyd. No. 12

RAIN GARDEN ROUTED

Hydrograph type = Reservoir Peak discharge = 0.014 cfsStorm frequency = 5 yrs Time to peak = 1102 minTime interval = 2 min Hyd. volume = 263 cuftInflow hyd. No. = 11 - POST TO RAIN GARDENMax. Elevation = 375.50 ftReservoir name = RAIN GARDEN 1 Max. Storage = 1,468 cuft


36

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

0.10 0.10

0.20 0.20

0.30 0.30

0.40 0.40

0.50 0.50

0.60 0.60

0.70 0.70

0.80 0.80

0.90 0.90

1.00 1.00

Q (cfs)

Time (min)




Hyd. No. 14

COMBINED

Hydrograph type = Combine Peak discharge = 0.237 cfsStorm frequency = 5 yrs Time to peak = 718 minTime interval = 2 min Hyd. volume = 4,133 cuftInflow hyds. = 2, 9, 12 Contrib. drain. area = 0.080 ac

37

0 240 480 720 960 1200 1440 1680 1920

Q (cfs)

0.00 0.00

0.05 0.05

0.10 0.10

0.15 0.15

0.20 0.20

0.25 0.25

0.30 0.30

0.35 0.35

0.40 0.40

0.45 0.45

0.50 0.50

Q (cfs)

Time (min)









5 Reservoir 0.054 2 1402 387 4 378.02 12,976 BED 1 ROUTED





12 Reservoir 0.049 2 810 874 11 375.51 1,493 RAIN GARDEN ROUTED





Hyd. No. 1

PRE-DEV


39

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

Q (cfs)

Time (min)


Hyd No. 1


Hyd. No. 2

BYPASS


40

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

0.05 0.05

0.10 0.10

0.15 0.15

0.20 0.20

0.25 0.25

0.30 0.30

0.35 0.35

0.40 0.40

0.45 0.45

0.50 0.50

Q (cfs)

Time (min)


Hyd No. 2


Hyd. No. 4

POST TO BED 1


41

0 120 240 360 480 600 720 840 960 1080 1200

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

5.00 5.00

6.00 6.00

7.00 7.00

Q (cfs)

Time (min)


Hyd No. 4


Hyd. No. 5

BED 1 ROUTED

Hydrograph type = Reservoir Peak discharge = 0.054 cfsStorm frequency = 10 yrs Time to peak = 1402 minTime interval = 2 min Hyd. volume = 387 cuftInflow hyd. No. = 4 - POST TO BED 1 Max. Elevation = 378.02 ftReservoir name = BED 1 Max. Storage = 12,976 cuft


42

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

5.00 5.00

6.00 6.00

7.00 7.00

Q (cfs)

Time (min)




Hyd. No. 7

POST TO BED 2


43

0 120 240 360 480 600 720 840 960 1080 1200

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

5.00 5.00

6.00 6.00

7.00 7.00

Q (cfs)

Time (min)


Hyd No. 7


Hyd. No. 8



44

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

5.00 5.00

6.00 6.00

7.00 7.00

Q (cfs)

Time (min)




Hyd. No. 9

BED 2 ROUTED



45

0 240 480 720 960 1200 1440 1680 1920

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

5.00 5.00

6.00 6.00

7.00 7.00

Q (cfs)

Time (min)




Hyd. No. 11

POST TO RAIN GARDEN


46

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

Q (cfs)

Time (min)


Hyd No. 11


Hyd. No. 12

RAIN GARDEN ROUTED

Hydrograph type = Reservoir Peak discharge = 0.049 cfsStorm frequency = 10 yrs Time to peak = 810 minTime interval = 2 min Hyd. volume = 874 cuftInflow hyd. No. = 11 - POST TO RAIN GARDENMax. Elevation = 375.51 ftReservoir name = RAIN GARDEN 1 Max. Storage = 1,493 cuft


47

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

Q (cfs)

Time (min)




Hyd. No. 14

COMBINED


48

0 240 480 720 960 1200 1440 1680 1920

Q (cfs)

0.00 0.00

0.05 0.05

0.10 0.10

0.15 0.15

0.20 0.20

0.25 0.25

0.30 0.30

0.35 0.35

0.40 0.40

0.45 0.45

0.50 0.50

Q (cfs)

Time (min)














12 Reservoir 0.116 2 750 1,355 11 375.52 1,539 RAIN GARDEN ROUTED





Hyd. No. 1

PRE-DEV


50

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

5.00 5.00

6.00 6.00

Q (cfs)

Time (min)


Hyd No. 1


Hyd. No. 2

BYPASS


51

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

0.05 0.05

0.10 0.10

0.15 0.15

0.20 0.20

0.25 0.25

0.30 0.30

0.35 0.35

0.40 0.40

0.45 0.45

0.50 0.50

Q (cfs)

Time (min)


Hyd No. 2


Hyd. No. 4

POST TO BED 1


52

0 120 240 360 480 600 720 840 960 1080 1200

Q (cfs)

0.00 0.00

2.00 2.00

4.00 4.00

6.00 6.00

8.00 8.00

Q (cfs)

Time (min)


Hyd No. 4


Hyd. No. 5

BED 1 ROUTED

Hydrograph type = Reservoir Peak discharge = 0.114 cfsStorm frequency = 25 yrs Time to peak = 1006 minTime interval = 2 min Hyd. volume = 2,456 cuftInflow hyd. No. = 4 - POST TO BED 1 Max. Elevation = 378.04 ftReservoir name = BED 1 Max. Storage = 13,037 cuft


53

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

2.00 2.00

4.00 4.00

6.00 6.00

8.00 8.00

Q (cfs)

Time (min)




Hyd. No. 7

POST TO BED 2


54

0 120 240 360 480 600 720 840 960 1080 1200

Q (cfs)

0.00 0.00

2.00 2.00

4.00 4.00

6.00 6.00

8.00 8.00

Q (cfs)

Time (min)


Hyd No. 7


Hyd. No. 8



55

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

2.00 2.00

4.00 4.00

6.00 6.00

8.00 8.00

Q (cfs)

Time (min)




Hyd. No. 9

BED 2 ROUTED



56

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 1680 1800

Q (cfs)

0.00 0.00

2.00 2.00

4.00 4.00

6.00 6.00

8.00 8.00

Q (cfs)

Time (min)




Hyd. No. 11

POST TO RAIN GARDEN


57

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

Q (cfs)

Time (min)


Hyd No. 11


Hyd. No. 12

RAIN GARDEN ROUTED

Hydrograph type = Reservoir Peak discharge = 0.116 cfsStorm frequency = 25 yrs Time to peak = 750 minTime interval = 2 min Hyd. volume = 1,355 cuftInflow hyd. No. = 11 - POST TO RAIN GARDENMax. Elevation = 375.52 ftReservoir name = RAIN GARDEN 1 Max. Storage = 1,539 cuft


58

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

Q (cfs)

Time (min)




Hyd. No. 14

COMBINED


59

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 1680 1800

Q (cfs)

0.00 0.00

0.10 0.10

0.20 0.20

0.30 0.30

0.40 0.40

0.50 0.50

0.60 0.60

0.70 0.70

0.80 0.80

0.90 0.90

1.00 1.00

Q (cfs)

Time (min)




Hyd. No. 1

PRE-DEV


61

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

5.00 5.00

6.00 6.00

7.00 7.00

Q (cfs)

Time (min)


Hyd No. 1


Hyd. No. 2

BYPASS


62

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440

Q (cfs)

0.00 0.00

0.05 0.05

0.10 0.10

0.15 0.15

0.20 0.20

0.25 0.25

0.30 0.30

0.35 0.35

0.40 0.40

0.45 0.45

0.50 0.50

Q (cfs)

Time (min)


Hyd No. 2


Hyd. No. 4

POST TO BED 1


63

0 120 240 360 480 600 720 840 960 1080 1200

Q (cfs)

0.00 0.00

2.00 2.00

4.00 4.00

6.00 6.00

8.00 8.00

10.00 10.00

Q (cfs)

Time (min)


Hyd No. 4


Hyd. No. 5

BED 1 ROUTED



64

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

2.00 2.00

4.00 4.00

6.00 6.00

8.00 8.00

10.00 10.00

Q (cfs)

Time (min)




Hyd. No. 7

POST TO BED 2


65

0 120 240 360 480 600 720 840 960 1080 1200

Q (cfs)

0.00 0.00

2.00 2.00

4.00 4.00

6.00 6.00

8.00 8.00

10.00 10.00

Q (cfs)

Time (min)


Hyd No. 7


Hyd. No. 8



66

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

2.00 2.00

4.00 4.00

6.00 6.00

8.00 8.00

10.00 10.00

Q (cfs)

Time (min)




Hyd. No. 9

BED 2 ROUTED



67

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 1680

Q (cfs)

0.00 0.00

2.00 2.00

4.00 4.00

6.00 6.00

8.00 8.00

10.00 10.00

Q (cfs)

Time (min)




Hyd. No. 11

POST TO RAIN GARDEN


68

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

Q (cfs)

Time (min)


Hyd No. 11


Hyd. No. 12

RAIN GARDEN ROUTED



69

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

Q (cfs)

Time (min)




Hyd. No. 14

COMBINED


70

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 1680

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

Q (cfs)

Time (min)







2 SCS Runoff 0.701 2 716 1,439 ------ ------ ------ BYPASS












Hyd. No. 1

PRE-DEV


72

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

2.00 2.00

4.00 4.00

6.00 6.00

8.00 8.00

10.00 10.00

12.00 12.00

Q (cfs)

Time (min)


Hyd No. 1


Hyd. No. 2

BYPASS


73

0 120 240 360 480 600 720 840 960 1080 1200 1320

Q (cfs)

0.00 0.00

0.10 0.10

0.20 0.20

0.30 0.30

0.40 0.40

0.50 0.50

0.60 0.60

0.70 0.70

0.80 0.80

0.90 0.90

1.00 1.00

Q (cfs)

Time (min)


Hyd No. 2


Hyd. No. 4

POST TO BED 1


74

0 120 240 360 480 600 720 840 960 1080 1200

Q (cfs)

0.00 0.00

2.00 2.00

4.00 4.00

6.00 6.00

8.00 8.00

10.00 10.00

12.00 12.00

Q (cfs)

Time (min)


Hyd No. 4


Hyd. No. 5

BED 1 ROUTED



75

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

2.00 2.00

4.00 4.00

6.00 6.00

8.00 8.00

10.00 10.00

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Q (cfs)

Time (min)




Hyd. No. 7

POST TO BED 2


76

0 120 240 360 480 600 720 840 960 1080 1200

Q (cfs)

0.00 0.00

2.00 2.00

4.00 4.00

6.00 6.00

8.00 8.00

10.00 10.00

12.00 12.00

Q (cfs)

Time (min)


Hyd No. 7


Hyd. No. 8



77

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

2.00 2.00

4.00 4.00

6.00 6.00

8.00 8.00

10.00 10.00

12.00 12.00

Q (cfs)

Time (min)




Hyd. No. 9

BED 2 ROUTED



78

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

2.00 2.00

4.00 4.00

6.00 6.00

8.00 8.00

10.00 10.00

12.00 12.00

Q (cfs)

Time (min)




Hyd. No. 11

POST TO RAIN GARDEN


79

0 120 240 360 480 600 720 840 960 1080 1200 1320

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

Q (cfs)

Time (min)


Hyd No. 11


Hyd. No. 12

RAIN GARDEN ROUTED



80

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

Q (cfs)

Time (min)




Hyd. No. 14

COMBINED


81

0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560

Q (cfs)

0.00 0.00

1.00 1.00

2.00 2.00

3.00 3.00

4.00 4.00

5.00 5.00

6.00 6.00

7.00 7.00

Q (cfs)

Time (min)



Chatham Financial Stormwater Management Report Kennett Township, Chester County Page E

APPENDIX E

STORMWATER CONVEYANCE CALCULATIONS

Title:Riprap Apron DesignMinimum Tailwater Condition

Source:PA DEPErosion & Sediment Pollution Control Program Manual



BYPASS - 24” HDPE

Q100=14.37 cfsBarrel=18”LA=14’Min. Width=4.5’Max. Width=18.5’Rock Size=R-4 (6”)Rock Depth=18”

Title:Riprap Apron DesignMinimum Tailwater Condition

Source:PA DEPErosion & Sediment Pollution Control Program Manual



UG 2

Q100=6.32 cfsBarrel=15”LA=8’Min. Width=4’Max. Width=12’Rock Size=R-4 (6”)Rock Depth=18”

DESIGN STORM = 100-yrCOMPUTATION TABLE - STORM SEWER DESIGN I 100 = 8.2 IN/HR

DRAINAGE AREA

INLET NO. STA. A CDelta CA

Sum CA

DT �TRAINFALL

INTENSITYENTERING Q INLET

DISCHARGE Q PIPE

LENGTH OF PIPE

SLOPE OF PIPE TYPE OF PIPEMANNINGS N

VALUESIZE OF

PIPEFULL FLOW VELOCITY

PIPE CAPACITY FLOWING

FULL SLOPE

ACRES ACRES ACRES MIN. MIN. IN/HR. C.F.S. C.F.S. FEET FT/FT IN. F.P.S. C.F.S.

44 0.0132 RCP 0.012 12 5.66 4.45

92 0.0200 HDPE 0.012 15 8.09 9.92

BYPASS FLOW COMBINED 14.37 465 0.0050 HDPE 0.012 24 5.53 17.38

BYPASS FLOW EX 15" HDPE

BYPASS FLOW EX 12" RCP

TIME

CHATHAM FINANCIALKENNETT TOWNSHIP, CHESTER COUNTY, PA

JOB NUMBER - 2731REVISION - 0 12/16/2016

BY: CMD

Chatham Financial Stormwater Management Report Kennett Township, Chester County Page F

APPENDIX F

NRCS SOILS REPORT

United StatesDepartment ofAgriculture

A product of the NationalCooperative Soil Survey,a joint effort of the UnitedStates Department ofAgriculture and otherFederal agencies, Stateagencies including theAgricultural ExperimentStations, and localparticipants

Custom Soil ResourceReport for

Chester County,Pennsylvania

NaturalResourcesConservationService

December 14, 2016

PrefaceSoil surveys contain information that affects land use planning in survey areas. Theyhighlight soil limitations that affect various land uses and provide information aboutthe properties of the soils in the survey areas. Soil surveys are designed for manydifferent users, including farmers, ranchers, foresters, agronomists, urban planners,community officials, engineers, developers, builders, and home buyers. Also,conservationists, teachers, students, and specialists in recreation, waste disposal,and pollution control can use the surveys to help them understand, protect, or enhancethe environment.

Various land use regulations of Federal, State, and local governments may imposespecial restrictions on land use or land treatment. Soil surveys identify soil propertiesthat are used in making various land use or land treatment decisions. The informationis intended to help the land users identify and reduce the effects of soil limitations onvarious land uses. The landowner or user is responsible for identifying and complyingwith existing laws and regulations.

Although soil survey information can be used for general farm, local, and wider areaplanning, onsite investigation is needed to supplement this information in some cases.Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/portal/nrcs/main/soils/health/) and certain conservation and engineering applications. Formore detailed information, contact your local USDA Service Center (http://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State SoilScientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/?cid=nrcs142p2_053951).

Great differences in soil properties can occur within short distances. Some soils areseasonally wet or subject to flooding. Some are too unstable to be used as afoundation for buildings or roads. Clayey or wet soils are poorly suited to use as septictank absorption fields. A high water table makes a soil poorly suited to basements orunderground installations.

The National Cooperative Soil Survey is a joint effort of the United States Departmentof Agriculture and other Federal agencies, State agencies including the AgriculturalExperiment Stations, and local agencies. The Natural Resources ConservationService (NRCS) has leadership for the Federal part of the National Cooperative SoilSurvey.

Information about soils is updated periodically. Updated information is availablethrough the NRCS Web Soil Survey, the site for official soil survey information.

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programsand activities on the basis of race, color, national origin, age, disability, and whereapplicable, sex, marital status, familial status, parental status, religion, sexualorientation, genetic information, political beliefs, reprisal, or because all or a part of anindividual's income is derived from any public assistance program. (Not all prohibitedbases apply to all programs.) Persons with disabilities who require alternative means

2

http://www.nrcs.usda.gov/wps/portal/nrcs/main/soils/health/

http://www.nrcs.usda.gov/wps/portal/nrcs/main/soils/health/

http://offices.sc.egov.usda.gov/locator/app?agency=nrcs

http://offices.sc.egov.usda.gov/locator/app?agency=nrcs

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/?cid=nrcs142p2_053951

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/?cid=nrcs142p2_053951

for communication of program information (Braille, large print, audiotape, etc.) shouldcontact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file acomplaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272(voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider andemployer.

3

ContentsPreface....................................................................................................................2How Soil Surveys Are Made..................................................................................5Soil Map..................................................................................................................7

Soil Map................................................................................................................8Legend..................................................................................................................9Map Unit Legend................................................................................................10Map Unit Descriptions........................................................................................10

Chester County, Pennsylvania........................................................................12GdB—Gladstone gravelly loam, 3 to 8 percent slopes................................12UrkB—Urban land-Edgemont complex, 0 to 8 percent slopes....................13

References............................................................................................................16

4

How Soil Surveys Are MadeSoil surveys are made to provide information about the soils and miscellaneous areasin a specific area. They include a description of the soils and miscellaneous areas andtheir location on the landscape and tables that show soil properties and limitationsaffecting various uses. Soil scientists observed the steepness, length, and shape ofthe slopes; the general pattern of drainage; the kinds of crops and native plants; andthe kinds of bedrock. They observed and described many soil profiles. A soil profile isthe sequence of natural layers, or horizons, in a soil. The profile extends from thesurface down into the unconsolidated material in which the soil formed or from thesurface down to bedrock. The unconsolidated material is devoid of roots and otherliving organisms and has not been changed by other biological activity.

Currently, soils are mapped according to the boundaries of major land resource areas(MLRAs). MLRAs are geographically associated land resource units that sharecommon characteristics related to physiography, geology, climate, water resources,soils, biological resources, and land uses (USDA, 2006). Soil survey areas typicallyconsist of parts of one or more MLRA.

The soils and miscellaneous areas in a survey area occur in an orderly pattern that isrelated to the geology, landforms, relief, climate, and natural vegetation of the area.Each kind of soil and miscellaneous area is associated with a particular kind oflandform or with a segment of the landform. By observing the soils and miscellaneousareas in the survey area and relating their position to specific segments of thelandform, a soil scientist develops a concept, or model, of how they were formed. Thus,during mapping, this model enables the soil scientist to predict with a considerabledegree of accuracy the kind of soil or miscellaneous area at a specific location on thelandscape.

Commonly, individual soils on the landscape merge into one another as theircharacteristics gradually change. To construct an accurate soil map, however, soilscientists must determine the boundaries between the soils. They can observe onlya limited number of soil profiles. Nevertheless, these observations, supplemented byan understanding of the soil-vegetation-landscape relationship, are sufficient to verifypredictions of the kinds of soil in an area and to determine the boundaries.

Soil scientists recorded the characteristics of the soil profiles that they studied. Theynoted soil color, texture, size and shape of soil aggregates, kind and amount of rockfragments, distribution of plant roots, reaction, and other features that enable them toidentify soils. After describing the soils in the survey area and determining theirproperties, the soil scientists assigned the soils to taxonomic classes (units).Taxonomic classes are concepts. Each taxonomic class has a set of soilcharacteristics with precisely defined limits. The classes are used as a basis forcomparison to classify soils systematically. Soil taxonomy, the system of taxonomicclassification used in the United States, is based mainly on the kind and character ofsoil properties and the arrangement of horizons within the profile. After the soilscientists classified and named the soils in the survey area, they compared the

5

individual soils with similar soils in the same taxonomic class in other areas so thatthey could confirm data and assemble additional data based on experience andresearch.

The objective of soil mapping is not to delineate pure map unit components; theobjective is to separate the landscape into landforms or landform segments that havesimilar use and management requirements. Each map unit is defined by a uniquecombination of soil components and/or miscellaneous areas in predictableproportions. Some components may be highly contrasting to the other components ofthe map unit. The presence of minor components in a map unit in no way diminishesthe usefulness or accuracy of the data. The delineation of such landforms andlandform segments on the map provides sufficient information for the development ofresource plans. If intensive use of small areas is planned, onsite investigation isneeded to define and locate the soils and miscellaneous areas.

Soil scientists make many field observations in the process of producing a soil map.The frequency of observation is dependent upon several factors, including scale ofmapping, intensity of mapping, design of map units, complexity of the landscape, andexperience of the soil scientist. Observations are made to test and refine the soil-landscape model and predictions and to verify the classification of the soils at specificlocations. Once the soil-landscape model is refined, a significantly smaller number ofmeasurements of individual soil properties are made and recorded. Thesemeasurements may include field measurements, such as those for color, depth tobedrock, and texture, and laboratory measurements, such as those for content ofsand, silt, clay, salt, and other components. Properties of each soil typically vary fromone point to another across the landscape.

Observations for map unit components are aggregated to develop ranges ofcharacteristics for the components. The aggregated values are presented. Directmeasurements do not exist for every property presented for every map unitcomponent. Values for some properties are estimated from combinations of otherproperties.

While a soil survey is in progress, samples of some of the soils in the area generallyare collected for laboratory analyses and for engineering tests. Soil scientists interpretthe data from these analyses and tests as well as the field-observed characteristicsand the soil properties to determine the expected behavior of the soils under differentuses. Interpretations for all of the soils are field tested through observation of the soilsin different uses and under different levels of management. Some interpretations aremodified to fit local conditions, and some new interpretations are developed to meetlocal needs. Data are assembled from other sources, such as research information,production records, and field experience of specialists. For example, data on cropyields under defined levels of management are assembled from farm records and fromfield or plot experiments on the same kinds of soil.

Predictions about soil behavior are based not only on soil properties but also on suchvariables as climate and biological activity. Soil conditions are predictable over longperiods of time, but they are not predictable from year to year. For example, soilscientists can predict with a fairly high degree of accuracy that a given soil will havea high water table within certain depths in most years, but they cannot predict that ahigh water table will always be at a specific level in the soil on a specific date.

After soil scientists located and identified the significant natural bodies of soil in thesurvey area, they drew the boundaries of these bodies on aerial photographs andidentified each as a specific map unit. Aerial photographs show trees, buildings, fields,roads, and rivers, all of which help in locating boundaries accurately.

Custom Soil Resource Report

6

Soil MapThe soil map section includes the soil map for the defined area of interest, a list of soilmap units on the map and extent of each map unit, and cartographic symbolsdisplayed on the map. Also presented are various metadata about data used toproduce the map, and a description of each soil map unit.

7

8

Custom Soil Resource ReportSoil Map

4411

370

4411

390

4411

410

4411

430

4411

450

4411

470

4411

490

4411

510

4411

530

4411

370

4411

390

4411

410

4411

430

4411

450

4411

470

4411

490

4411

510

4411

530

440500 440520 440540 440560 440580 440600 440620 440640 440660 440680 440700 440720 440740

440480 440500 440520 440540 440560 440580 440600 440620 440640 440660 440680 440700 440720 440740

39° 51' 6'' N75

° 4

1' 4

4'' W

39° 51' 6'' N

75° 4

1' 3

3'' W

39° 51' 0'' N

75° 4

1' 4

4'' W

39° 51' 0'' N

75° 4

1' 3

3'' W

N

Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 18N WGS840 50 100 200 300

Feet0 15 30 60 90

MetersMap Scale: 1:1,220 if printed on A landscape (11" x 8.5") sheet.

Warning: Soil Map may not be valid at this scale.

MAP LEGEND MAP INFORMATION

Area of Interest (AOI)Area of Interest (AOI)

SoilsSoil Map Unit Polygons

Soil Map Unit Lines

Soil Map Unit Points

Special Point FeaturesBlowout

Borrow Pit

Clay Spot

Closed Depression

Gravel Pit

Gravelly Spot

Landfill

Lava Flow

Marsh or swamp

Mine or Quarry

Miscellaneous Water

Perennial Water

Rock Outcrop

Saline Spot

Sandy Spot

Severely Eroded Spot

Sinkhole

Slide or Slip

Sodic Spot

Spoil Area

Stony Spot

Very Stony Spot

Wet Spot

Other

Special Line Features

Water FeaturesStreams and Canals

TransportationRails

Interstate Highways

US Routes

Major Roads

Local Roads

BackgroundAerial Photography

The soil surveys that comprise your AOI were mapped at 1:24,000.

Warning: Soil Map may not be valid at this scale.

Enlargement of maps beyond the scale of mapping can causemisunderstanding of the detail of mapping and accuracy of soil lineplacement. The maps do not show the small areas of contrastingsoils that could have been shown at a more detailed scale.

Please rely on the bar scale on each map sheet for mapmeasurements.

Source of Map: Natural Resources Conservation ServiceWeb Soil Survey URL: http://websoilsurvey.nrcs.usda.govCoordinate System: Web Mercator (EPSG:3857)

Maps from the Web Soil Survey are based on the Web Mercatorprojection, which preserves direction and shape but distortsdistance and area. A projection that preserves area, such as theAlbers equal-area conic projection, should be used if more accuratecalculations of distance or area are required.

This product is generated from the USDA-NRCS certified data as ofthe version date(s) listed below.

Soil Survey Area: Chester County, PennsylvaniaSurvey Area Data: Version 8, Sep 19, 2016

Soil map units are labeled (as space allows) for map scales 1:50,000or larger.

Date(s) aerial images were photographed: Mar 19, 2011—May 7,2011

The orthophoto or other base map on which the soil lines werecompiled and digitized probably differs from the backgroundimagery displayed on these maps. As a result, some minor shiftingof map unit boundaries may be evident.


9

Map Unit Legend

Chester County, Pennsylvania (PA029)

Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI

GdB Gladstone gravelly loam, 3 to 8percent slopes

5.9 99.4%

UrkB Urban land-Edgemont complex,0 to 8 percent slopes

0.0 0.6%

Totals for Area of Interest 5.9 100.0%

Map Unit DescriptionsThe map units delineated on the detailed soil maps in a soil survey represent the soilsor miscellaneous areas in the survey area. The map unit descriptions, along with themaps, can be used to determine the composition and properties of a unit.

A map unit delineation on a soil map represents an area dominated by one or moremajor kinds of soil or miscellaneous areas. A map unit is identified and namedaccording to the taxonomic classification of the dominant soils. Within a taxonomicclass there are precisely defined limits for the properties of the soils. On the landscape,however, the soils are natural phenomena, and they have the characteristic variabilityof all natural phenomena. Thus, the range of some observed properties may extendbeyond the limits defined for a taxonomic class. Areas of soils of a single taxonomicclass rarely, if ever, can be mapped without including areas of other taxonomicclasses. Consequently, every map unit is made up of the soils or miscellaneous areasfor which it is named and some minor components that belong to taxonomic classesother than those of the major soils.

Most minor soils have properties similar to those of the dominant soil or soils in themap unit, and thus they do not affect use and management. These are callednoncontrasting, or similar, components. They may or may not be mentioned in aparticular map unit description. Other minor components, however, have propertiesand behavioral characteristics divergent enough to affect use or to require differentmanagement. These are called contrasting, or dissimilar, components. They generallyare in small areas and could not be mapped separately because of the scale used.Some small areas of strongly contrasting soils or miscellaneous areas are identifiedby a special symbol on the maps. If included in the database for a given area, thecontrasting minor components are identified in the map unit descriptions along withsome characteristics of each. A few areas of minor components may not have beenobserved, and consequently they are not mentioned in the descriptions, especiallywhere the pattern was so complex that it was impractical to make enough observationsto identify all the soils and miscellaneous areas on the landscape.

The presence of minor components in a map unit in no way diminishes the usefulnessor accuracy of the data. The objective of mapping is not to delineate pure taxonomicclasses but rather to separate the landscape into landforms or landform segments thathave similar use and management requirements. The delineation of such segmentson the map provides sufficient information for the development of resource plans. If


10

intensive use of small areas is planned, however, onsite investigation is needed todefine and locate the soils and miscellaneous areas.

An identifying symbol precedes the map unit name in the map unit descriptions. Eachdescription includes general facts about the unit and gives important soil propertiesand qualities.

Soils that have profiles that are almost alike make up a soil series. Except fordifferences in texture of the surface layer, all the soils of a series have major horizonsthat are similar in composition, thickness, and arrangement.

Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity,degree of erosion, and other characteristics that affect their use. On the basis of suchdifferences, a soil series is divided into soil phases. Most of the areas shown on thedetailed soil maps are phases of soil series. The name of a soil phase commonlyindicates a feature that affects use or management. For example, Alpha silt loam, 0to 2 percent slopes, is a phase of the Alpha series.

Some map units are made up of two or more major soils or miscellaneous areas.These map units are complexes, associations, or undifferentiated groups.

A complex consists of two or more soils or miscellaneous areas in such an intricatepattern or in such small areas that they cannot be shown separately on the maps. Thepattern and proportion of the soils or miscellaneous areas are somewhat similar in allareas. Alpha-Beta complex, 0 to 6 percent slopes, is an example.

An association is made up of two or more geographically associated soils ormiscellaneous areas that are shown as one unit on the maps. Because of present oranticipated uses of the map units in the survey area, it was not considered practicalor necessary to map the soils or miscellaneous areas separately. The pattern andrelative proportion of the soils or miscellaneous areas are somewhat similar. Alpha-Beta association, 0 to 2 percent slopes, is an example.

An undifferentiated group is made up of two or more soils or miscellaneous areas thatcould be mapped individually but are mapped as one unit because similarinterpretations can be made for use and management. The pattern and proportion ofthe soils or miscellaneous areas in a mapped area are not uniform. An area can bemade up of only one of the major soils or miscellaneous areas, or it can be made upof all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example.

Some surveys include miscellaneous areas. Such areas have little or no soil materialand support little or no vegetation. Rock outcrop is an example.


11


GdB—Gladstone gravelly loam, 3 to 8 percent slopes

Map Unit SettingNational map unit symbol: 2v7gkElevation: 250 to 1,200 feetMean annual precipitation: 30 to 64 inchesMean annual air temperature: 46 to 79 degrees FFrost-free period: 131 to 178 daysFarmland classification: All areas are prime farmland

Map Unit CompositionGladstone and similar soils: 85 percentMinor components: 15 percentEstimates are based on observations, descriptions, and transects of the mapunit.

Description of Gladstone

SettingLandform: HillsLandform position (two-dimensional): ShoulderLandform position (three-dimensional): Side slopeDown-slope shape: LinearAcross-slope shape: ConvexParent material: Loamy colluvium derived from granite and gneiss and/or loamy

residuum weathered from granite and gneiss

Typical profileAp - 0 to 10 inches: gravelly loamBt1 - 10 to 22 inches: sandy clay loamBt2 - 22 to 37 inches: loamC - 37 to 66 inches: sandy loamR - 66 to 76 inches: bedrock

Properties and qualitiesSlope: 3 to 8 percentDepth to restrictive feature: 60 to 80 inches to lithic bedrockNatural drainage class: Well drainedCapacity of the most limiting layer to transmit water (Ksat): Very low to moderately

low (0.00 to 0.06 in/hr)Depth to water table: More than 80 inchesFrequency of flooding: NoneFrequency of ponding: NoneAvailable water storage in profile: Moderate (about 8.4 inches)

Interpretive groupsLand capability classification (irrigated): None specifiedLand capability classification (nonirrigated): 2eHydrologic Soil Group: BHydric soil rating: No

Minor Components

CalifonPercent of map unit: 5 percent


12

Landform: FlatsLandform position (two-dimensional): FootslopeLandform position (three-dimensional): Base slopeDown-slope shape: ConcaveAcross-slope shape: LinearHydric soil rating: No

AnnandalePercent of map unit: 5 percentLandform: HillsLandform position (two-dimensional): SummitLandform position (three-dimensional): InterfluveDown-slope shape: ConvexAcross-slope shape: LinearHydric soil rating: No

ParkerPercent of map unit: 5 percentLandform: HillsLandform position (two-dimensional): ShoulderLandform position (three-dimensional): Side slopeDown-slope shape: ConvexAcross-slope shape: LinearHydric soil rating: No

UrkB—Urban land-Edgemont complex, 0 to 8 percent slopes

Map Unit SettingNational map unit symbol: pjnbElevation: 500 to 2,400 feetMean annual precipitation: 35 to 50 inchesMean annual air temperature: 46 to 57 degrees FFrost-free period: 120 to 185 daysFarmland classification: Not prime farmland

Map Unit CompositionUrban land: 65 percentEdgemont and similar soils: 30 percentMinor components: 5 percentEstimates are based on observations, descriptions, and transects of the mapunit.

Description of Urban Land

SettingLandform: RidgesLandform position (two-dimensional): Shoulder, summitLandform position (three-dimensional): Nose slope, head slope, side slope,

interfluveParent material: Pavement, buildings and other artifically covered areas


13

Typical profileC - 0 to 6 inches: variable

Properties and qualitiesSlope: 0 to 8 percentDepth to restrictive feature: 10 to 99 inches to lithic bedrockAvailable water storage in profile: Very low (about 0.0 inches)

Interpretive groupsLand capability classification (irrigated): None specifiedLand capability classification (nonirrigated): 8sHydric soil rating: No

Description of Edgemont

SettingLandform: RidgesLandform position (two-dimensional): Shoulder, summitLandform position (three-dimensional): Nose slope, head slope, side slope,

interfluveDown-slope shape: Convex, linearAcross-slope shape: Convex, linearParent material: Residuum weathered from antietam quartzite; residuum weathered

from chickies quartzite and/or slate; residuum weathered from vintage dolomite

Typical profileA - 0 to 9 inches: channery loamBt - 9 to 25 inches: channery fine sandy loamC - 25 to 60 inches: very channery sandy loam

Properties and qualitiesSlope: 0 to 8 percentDepth to restrictive feature: 40 to 84 inches to lithic bedrockNatural drainage class: Well drainedRunoff class: Very lowCapacity of the most limiting layer to transmit water (Ksat): Moderately high to high

(0.60 to 6.00 in/hr)Depth to water table: More than 80 inchesFrequency of flooding: NoneFrequency of ponding: NoneAvailable water storage in profile: Low (about 5.5 inches)

Interpretive groupsLand capability classification (irrigated): None specifiedLand capability classification (nonirrigated): 2eHydrologic Soil Group: AHydric soil rating: No

Minor Components

BuchananPercent of map unit: 3 percentLandform: TerracesLandform position (two-dimensional): FootslopeLandform position (three-dimensional): MountainbaseDown-slope shape: Concave, linearAcross-slope shape: Concave, linear


14

Hydric soil rating: No

AndoverPercent of map unit: 2 percentLandform: DrainagewaysLandform position (two-dimensional): Toeslope, footslopeLandform position (three-dimensional): MountainbaseDown-slope shape: Linear, concaveAcross-slope shape: Linear, concaveHydric soil rating: Yes


15

ReferencesAmerican Association of State Highway and Transportation Officials (AASHTO). 2004.Standard specifications for transportation materials and methods of sampling andtesting. 24th edition.

American Society for Testing and Materials (ASTM). 2005. Standard classification ofsoils for engineering purposes. ASTM Standard D2487-00.

Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification ofwetlands and deep-water habitats of the United States. U.S. Fish and Wildlife ServiceFWS/OBS-79/31.

Federal Register. July 13, 1994. Changes in hydric soils of the United States.

Federal Register. September 18, 2002. Hydric soils of the United States.

Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric soilsin the United States.

National Research Council. 1995. Wetlands: Characteristics and boundaries.

Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service. U.S.Department of Agriculture Handbook 18. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_054262

Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for makingand interpreting soil surveys. 2nd edition. Natural Resources Conservation Service,U.S. Department of Agriculture Handbook 436. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053577

Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department ofAgriculture, Natural Resources Conservation Service. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580

Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service andDelaware Department of Natural Resources and Environmental Control, WetlandsSection.

United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps ofEngineers wetlands delineation manual. Waterways Experiment Station TechnicalReport Y-87-1.

United States Department of Agriculture, Natural Resources Conservation Service.National forestry manual. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/home/?cid=nrcs142p2_053374

United States Department of Agriculture, Natural Resources Conservation Service.National range and pasture handbook. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/landuse/rangepasture/?cid=stelprdb1043084

16

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_054262






http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/home/?cid=nrcs142p2_053374

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/home/?cid=nrcs142p2_053374

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/landuse/rangepasture/?cid=stelprdb1043084

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/landuse/rangepasture/?cid=stelprdb1043084

United States Department of Agriculture, Natural Resources Conservation Service.National soil survey handbook, title 430-VI. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/scientists/?cid=nrcs142p2_054242

United States Department of Agriculture, Natural Resources Conservation Service.2006. Land resource regions and major land resource areas of the United States, theCaribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296.http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053624

United States Department of Agriculture, Soil Conservation Service. 1961. Landcapability classification. U.S. Department of Agriculture Handbook 210. http://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf


17

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/scientists/?cid=nrcs142p2_054242

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/scientists/?cid=nrcs142p2_054242




http://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf

http://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf

Chatham Financial Stormwater Management Report Kennett Township, Chester County Page G

APPENDIX G

INFILTRATION TESTING REPORT

Chatham Financial Infiltration Test Report 235 Whitehorse Road Page 1 October 4, 2016 Kennett Township Chester County

STORMWATER INFILTRATION REPORT

FOR

235 WHITEHORSE ROAD

KENNETT TOWNSHIP CHESTER COUNTY

PREPARED FOR:

Chatham Financial 235 Whitehorse Road

Kennett Square, PA 19348

PREPARED BY:

D.L. Howell & Associates, Inc. 1250 Wrights Lane

West Chester, PA 19380

October 2016


Stormwater Infiltration Test Report

235 Whitehorse Road Kennett Township Chester County

On Monday and Tuesday, October 3-4, 2016, D.L. Howell and Associates, Inc. preformed hydraulic conductivity tests for the proposed stormwater management areas for the Chatham Financial property located at 235 Whitehorse Road in Kennett Township, Chester County. The purpose of the hydraulic conductivity testing was to determine site suitability for the proposed stormwater infiltration area associated with proposed improvements at the site (see development plan). Testing was conducted in general accordance with the Pennsylvania Department of Environmental Protection (PADEP)’s Pennsylvania Stormwater Best Management Practices Manual specifications, in a cased, sealed, borehole utilizing the falling head method designed to measure the vertical hydraulic conductivity of the soil. An approximate five inch diameter borehole was hand dug to the depth of the proposed bottom elevation of the infiltration structure and a 3 inch diameter PVC casing was installed. A mixture of bentonite and soil was placed around the annulus of the casing and packed to seal the casing in place. The casing was presoaked immediately prior to the start of the test to simulate field saturated conditions. A measured amount of water was poured into the sealed casing to begin the 30 minute presoak. After the final 30 minute presoaking period, the water in the casing was adjusted to a known depth and consecutively re-adjusted after each reading and the drop of the water column is measured. The test continued until the readings became stabilized or for a maximum of eight readings. A stabilized rate of drop means a difference of ¼ inch or less of drop between the highest and lowest readings of four consecutive readings. Within the proposed infiltration areas, a total of eight hydraulic conductivity tests were run at the elevations associated with the proposed infiltration elevations. One deep test pit was excavated at each test location to identify limiting conditions such as mottling, depth of bedrock, and depth of groundwater. Testing was to be conducted within the footprint of each proposed infiltration area.

� Infiltration Test 1 was conducted at approximately ± 8.0 feet below existing grade, which corresponds to an approximate infiltration elevation of 373.0. One deep test pit was excavated to a depth of approximately 10.0 feet below existing grade. Redoximorphic features were identified between 9-21 inches. It is D.L. Howell and Associates opinion that these redox features are not an indication of a true or permanent water table, but as the result of variable permeability within that soil horizon.


� Infiltration Test 2 was conducted at approximately ± 8.0 feet below existing grade, which corresponds to an approximate infiltration elevation of 374.0. One deep test pit was excavated at this location to a depth of 10.0 feet below existing grade. No limiting conditions were identified at the time of excavation.

� Infiltration Test 3 was conducted at approximately ± 10.0 feet below existing

grade, which corresponds to an approximate infiltration elevation of 374.0. One deep test pit was excavated at this location to a depth of 12.0 feet below existing grade. No limiting conditions were identified at the time of excavation.

Based on the hydraulic conductivity testing for the testing located within the footprint of the seepage bed, D.L. Howell & Associates, Inc., recommends the following infiltration rate for the soils underlying Test 1, 2, and 3: an infiltration rate of 3.663 inches per hour shall be used.

� Infiltration Test 4 was conducted at approximately ± 8.0 feet below existing grade, which corresponds to an approximate infiltration elevation of 374.0. One deep test pit was excavated to a depth of approximately 10.0 feet below existing grade. No limiting conditions were identified at the time of excavation.


grade, which corresponds to an approximate infiltration elevation of 372.0. One deep test pit was excavated at this location to a depth of 8.0 feet below existing grade. No limiting conditions were identified at the time of excavation.

� Infiltration Test 6 was proposed at approximately ± 6.0 feet below existing grade.

During excavation, redoximorphic features were identified between 26-96 inches. As a result, no infiltration testing was conducted at this location.

Based on the hydraulic conductivity testing for the testing located within the footprint of the seepage bed, D.L. Howell & Associates, Inc., recommends the following infiltration rate for the soils underlying Test 4 and Test 5: an infiltration rate of 1.723 inches per hour shall be used.

� Infiltration Test 7 was conducted at approximately ± 7.0 feet below existing grade, which corresponds to an approximate infiltration elevation of 375.0. One deep test pit was excavated to a depth of approximately 9.0 feet below existing grade. Redoximorphic features were identified between 15-73 inches. It is D.L. Howell and Associates opinion that these redox features are not an indication of a true or permanent water table, but as the result of variable permeability within the soil horizons.


grade, which corresponds to an approximate infiltration elevation of 375.0. One


deep test pit was excavated at this location to a depth of 9.0 feet below existing grade. No limiting conditions were identified at the time of excavation.

Based on the hydraulic conductivity testing for the testing located within the footprint of the seepage bed, D.L. Howell & Associates, Inc., recommends the following infiltration rate for the soils underlying Test 7 and Test 8: an infiltration rate of 1.532 inches per hour shall be used. Please reference plan drawings for exact locations and visual representation of infiltration tests and test pits. Results of the hydraulic conductivity testing and soil horizon descriptions can be found in the enclosed attachments. Hydraulic Conductivity Calculation Coefficient of Permeability: K = [A/(F*D*t)] x ln (h1 / h2) Where: K = permeability (inches per hour) A = cross sectional area of cased hole F = shape factor (2.75 constant of flat bottom) D = cased hole diameter t = time for head change from h1 to h2 h1 = initial height of water column in casing h2 = final height of water column in casing *Reference Soil Hydraulic Conductivity Analysis Form for infiltration testing data and Soil Morphology Form for soil profile data.

2731 DATE:BY:

Kennett Township, Chester County, Pa.Stormwater Infiltration Testing

Sunny 68 °FNone

1st 2nd 3rd 4th 5th 6th 7th 8th

10 10 10 10 10 10 10 108.25 6.25 6.00 6.00 6.00 n/a n/a n/a18 18 18 18 18 n/a n/a n/a


10 10 10 10 10 10 10 1013.50 11.75 10.75 10.75 10.75 10.75 n/a n/a

18 18 18 18 18.00 18 n/a n/a


10 10 10 10 10 10 10 1012.00 11.50 11.25 11.25 11.25 n/a n/a n/a

Pre-Soak

3018.00

ReadingsPre-Soak

ReadingsHole # Depth (Inches)

18

Time(min.)

Time(min.) 30Test 2 96

Drop(inches) 18.00

Stormwater Infiltration Testing &

Hydraulic Conductivity Calculations

Field Test Results

10/3/2016LOCATION: DD

Drop(inches)

Hole # Depth (Inches)Test 1 96

Initial Water Level Depth (inches)

JOB NO.:

MUNICIPALITY:235 Whitehorse Road

DESCRIPTION:

WEATHER CONDITIONS: TEMPERATURE:PRECIPITATION IN LAST 24 HOURS:

30

ReadingsHole # Depth (Inches) Pre-Soak

Initial Water Level Depth (inches) 18

Drop(inches) 18.00

Test 3 120Time(min.)

12.00 11.50 11.25 11.25 11.25 n/a n/a n/a18 18 18 18 18.00 n/a n/a n/a

Kv = Vertical Permeability 2.0844 (in/hour) 4.6749 (in/hour) 5.0422 (in/hour)A = Cross-sectional area of cased hole 7.0686 (Sq.in.) 7.0686 (Sq.in.) 7.0686 (Sq.in.)F = shape factor (2.75 constant for flat bottom) 2.75 (Units) 2.75 (Units) 2.75 (Units)D = cased hole diameter 3 (Inches) 3 (Inches) 3 (Inches)t = time for head to change from h1 to h2 0.1667 (hrs.) 0.1667 (hrs.) 0.1667 (hrs.)

h1 = initial height of water column in casing 18 (Inches) 18 (Inches) 18 (Inches)h2 = final height of water column in casing 12.00 (Inches) 7.25 (Inches) 6.75 (Inches)

3.934 (in./hr)3.663 (in./hr)

Test 3 ResultsTest 1 Results Test 2 Results

Determination of Hydraulic Conductivity (Kv)

Kv =

Average PermeabilityGeometric Mean

[ A/(F*D*t) ] * ln(h1/h2)

Drop(inches) 18.00Initial Water Level Depth (inches) 18

2731 DATE:BY:


SUNNY 69 °FNone


10 10 10 10 10 10 10 1011.25 10.75 10.75 10.50 10.50 n/a n/a n/a

18 18 18 18 18 n/a n/a n/a


30 30 30 30 30 30 30 306.00 5.75 5.75 5.75 n/a n/a n/a n/a18 18 18 18 n/a n/a n/a n/a

Pre-SoakTest 5 72

ReadingsPre-Soak


3018.00


Time(min.)

Time(min.) 30Drop(inches) 6.25


Kv =




Drop(inches)

Hole # Depth (Inches)

Field Test Results


JOB NO.:


DESCRIPTION:


[ A/(F*D*t) ] * ln(h1/h2)

Test 4 96

Kv = Vertical Permeability 4.5006 (in/hour) 0.6595 (in/hour)A = Cross-sectional area of cased hole 7.0686 (Sq.in.) 7.0686 (Sq.in.)F = shape factor (2.75 constant for flat bottom) 2.75 (Units) 2.75 (Units)D = cased hole diameter 3 (Inches) 3 (Inches)t = time for head to change from h1 to h2 0.1667 (hrs.) 0.5 (hrs.)

h1 = initial height of water column in casing 18 (Inches) 18 (Inches)h2 = final height of water column in casing 7.50 (Inches) 12.25 (Inches)

2.58 (in./hr)1.723 (in./hr)

Test 4 Results Test 5 Results


2731 DATE:BY:


SUNNY 69 °FNone


30 30 30 30 30 30 30 304.00 4.00 3.75 3.75 n/a n/a n/a n/a18 18 18 18 n/a n/a n/a n/a


10 10 10 10 10 10 10 1013.00 12.50 12.25 12.25 12.25 n/a n/a n/a

18 18 18 18 18 n/a n/a n/a

Pre-SoakTest 8 84

ReadingsPre-Soak


304.00


Time(min.)

Time(min.) 30Drop(inches) 18.00


Kv =




Drop(inches)

Hole # Depth (Inches)

Field Test Results


JOB NO.:


DESCRIPTION:


[ A/(F*D*t) ] * ln(h1/h2)

Test 7 84

Kv = Vertical Permeability 0.4003 (in/hour) 5.8665 (in/hour)A = Cross-sectional area of cased hole 7.0686 (Sq.in.) 7.0686 (Sq.in.)F = shape factor (2.75 constant for flat bottom) 2.75 (Units) 2.75 (Units)D = cased hole diameter 3 (Inches) 3 (Inches)t = time for head to change from h1 to h2 0.5 (hrs.) 0.1667 (hrs.)

h1 = initial height of water column in casing 18 (Inches) 18 (Inches)h2 = final height of water column in casing 14.25 (Inches) 5.75 (Inches)

3.133 (in./hr)1.532 (in./hr)

Test 7 Results Test 8 Results


INVESTIGATOR:

DATE: STATE: COUNTY:

MUNICIPALITY: CLIENT:

SUBDIVISION: SITE LOCATION:

Upper Lower Distrnct Topo A S

0 9 G S 0 SBK

9 21 G S 0 c m MA redox throughout

21 55 A C 0 MA

55 78 G S 0 GRAN

78 120 0 GRAN

TP1 DLH NUMBER:

10/3/2016

Texture NOTES

PA

KENNETT TWP

2731 DWDPIT NUMBER:

Depth BoundaryColor

10 YR 4/2

10 YR 5/1

10 YR 5/3

10 YR 6/2

SILTY CLAY LOAM

SILT LOAM

10 YR 4/4

CHESTER

CHATHAM FINANCIAL

235 WHITEHORSE ROAD

SILT LOAM

%CFsREDOX

Horizon Structure

N/A

CConsistence

MORPHOLOGIC DETERMINATION: SEWAGE STORMWATER SHWT SOILS

Soil Drainage Class:

FRI

d

SILT LOAM

SILTY CLAY LOAM

FRI

FIRM

FIRM

FRI

COMMENTS: This Deep Test pit was conducted at the Test 1 location. During excavation, redoximorphic features were identified between 9-21 inches below existing grade.SOIL TYPE: Soil Scientist Signature:

Soil Morphology Form

1250 Wrights Lane P: (610) 918-9002 West Chester, PA 19380 F: (610) 918-9003

LIMITING CONDITION: None Excessively Drained Somewhat Poorly Drained


Moderately Well Drained Very Poorly Drained

SOIL TYPE:

Type: Water Rock Mottling

Depth: +120"

Soil Scientist Signature:

Well Drained Poorly Drained

Excavator

120"

N

METHOD:

EXCAVATION DEPTH:

LANDSCAPE POSITION:

WEATHER:

SLOPE:

COVER:

71° slight breeze

Meadow

REDOX – Redoxymorphic features (Drainage Mottling) A/S/C – Abundance/Size/ContrastRoots/Pores – f – few, c – common, m – many / f – fine, m – medium, c – coarse

INVESTIGATOR:





0 8 A C 0 SBK

8 18 A C 0 MA

18 30 G S 0 MA

30 51 A C 0 MA

51 120 0 GRAN




71° slight breeze

Meadow

Excavator

120"

N

METHOD:

EXCAVATION DEPTH:

LANDSCAPE POSITION:

WEATHER:

SLOPE:

COVER:


Depth: +120"




FRI

FRI

VFIRM

FRI

COMMENTS: This Deep Test pit was conducted at the Test 2 location. No limiting conditions were identified at the time of excavation.

SOIL TYPE: Soil Drainage Class:

FRISANDY SILT

SILT LOAM

N/A

CConsistence


CHESTER

CHATHAM FINANCIAL

235 WHITEHORSE ROAD

SILT LOAM

%CFsREDOX

Horizon Structure

10 YR 4/2

10 YR 4/4

10 YR 5/2

10 YR 5/6

SILTY CLAY LOAM

SILT LOAM

VAR


2731 DWDPIT NUMBER:

Depth BoundaryColor

TP2 DLH NUMBER:

10/3/2016

Texture NOTES

PA

KENNETT TWP

INVESTIGATOR:





0 9 A C 0 SBK

9 37 A C 0 MA

37 48 G S 0 MA

48 89 A C 0 MA

89 144 0 GRAN


TP3 DLH NUMBER:

10/3/2016

Texture NOTES

PA

KENNETT TWP


2731 DWDPIT NUMBER:

Depth BoundaryColor

10 YR 4/2

10 YR 5/3

5 YR 4/6

10 YR 5/3

SILTY CLAY LOAM

SILTY CLAY LOAM

VAR

CHESTER

CHATHAM FINANCIAL

235 WHITEHORSE ROAD

SILT LOAM

%CFsREDOX

Horizon Structure

N/A

CConsistence



FRISANDY SILT

SILTY CLAY LOAM


FRI

FIRM

FIRM

FIRM


SOIL TYPE:


Depth: +144"



Excavator

144"

E

METHOD:

EXCAVATION DEPTH:

LANDSCAPE POSITION:

WEATHER:

SLOPE:

COVER:

71° slight breeze

Meadow



INVESTIGATOR:





0 7 A C 0 GRAN

7 64 G S 0 MA

64 120 0 GRAN




71° slight breeze

Meadow

Excavator

120"

E

METHOD:

EXCAVATION DEPTH:

LANDSCAPE POSITION:

WEATHER:

SLOPE:

COVER:


Depth: +120"




FRI

FRI

FRI



SILT LOAM

N/A

CConsistence


CHESTER

CHATHAM FINANCIAL

235 WHITEHORSE ROAD

SILT LOAM

%CFsREDOX

Horizon Structure

10 YR 4/2

10 YR 5/4

VAR SANDY SILT


2731 DWDPIT NUMBER:

Depth BoundaryColor

TP4 DLH NUMBER:

10/3/2016

Texture NOTES

PA

KENNETT TWP

INVESTIGATOR:





0 11 G S 0 GRAN

11 35 A W 0 MA

35 69 A IR 0 GRAN

69 96 0 GRAN


TP5 DLH NUMBER:

10/4/2016

Texture NOTES

PA

KENNETT TWP


2731 DWDPIT NUMBER:

Depth BoundaryColor

10 YR 4/2

10 YR 5/4

VAR

5 YR 4/4

SANDY SILT

SANDY SILT

CHESTER

CHATHAM FINANCIAL

235 WHITEHORSE ROAD

SILT LOAM

%CFsREDOX

Horizon Structure

N/A

CConsistence



SILTY CLAY LOAM


FRI

FIRM

FRI

FRI


SOIL TYPE:


Depth: +96"



Excavator

96"

Central

METHOD:

EXCAVATION DEPTH:

LANDSCAPE POSITION:

WEATHER:

SLOPE:

COVER:

69° slight breeze

Meadow



INVESTIGATOR:





0 9 G S 0 GRAN

9 15 A W 0 MA

15 38 G S 0 c c SBK redox throughout

38 73 A C 0 c m MA redox throughout

73 108 0 GRAN


TP7 DLH NUMBER:

10/4/2016

Texture NOTES

PA

KENNETT TWP


2731 DWDPIT NUMBER:

Depth BoundaryColor

10 YR 3/2

10 YR 5/2

10 YR 5/6

10 YR 6/1

SILTY CLAY LOAM

SILTY CLAY LOAM

VAR

CHESTER

CHATHAM FINANCIAL

235 WHITEHORSE ROAD

SILT LOAM

%CFsREDOX

Horizon Structure

N/A

CConsistence



FRI

d

d

SANDY SILT

SILT LOAM


FRI

FRI

FRI

FIRM

COMMENTS: This Deep Test pit was conducted at the Test 7 location. During excavation, redox features were identified from approximately 15-73 inches below existing grade.SOIL TYPE:


Depth: +108"



Excavator

108"

NW

METHOD:

EXCAVATION DEPTH:

LANDSCAPE POSITION:

WEATHER:

SLOPE:

COVER:

69° slight breeze

Meadow



INVESTIGATOR:





0 10 A W 0 GRAN

10 23 G S 0 SBK

23 62 G S 0 MA

62 108 0 GRAN




69° slight breeze

Meadow

Excavator

108"

SW

METHOD:

EXCAVATION DEPTH:

LANDSCAPE POSITION:

WEATHER:

SLOPE:

COVER:


Depth: +108"




FRI

FIRM

FRI

FRI



SILTY CLAY LOAM

N/A

CConsistence


CHESTER

CHATHAM FINANCIAL

235 WHITEHORSE ROAD

SILT LOAM

%CFsREDOX

Horizon Structure

10 YR 3/2

10 YR 5/6

7.5 YR 5/6

VAR

SILT LOAM

SANDY SILT


2731 DWDPIT NUMBER:

Depth BoundaryColor

TP8 DLH NUMBER:

10/4/2016

Texture NOTES

PA

KENNETT TWP

Chatham Financial Stormwater Management Report Kennett Township, Chester County Page H

APPENDIX H

DEWATERING CALCULATIONS

STORMWATER STRUCTURESTORMWATER STRUCTUREDEWATERING CALCULATIONS

DATE: 12/16/2016

BY: CMD

JOB NO.: 2731 PROJECT: Chatham FinancialJOB NO.: 2731 PROJECT:DESCRIPTION: DEWATERING CALCULATION

TOWNSHIP: Kennett

INFILTRATION BED 1

PERC. RATE 1.532 IN/HR Hydraulic Conductivity Rate - Geometric Mean2 Factor of Safety

Chatham Financial

DESIGN RATE 0.766 IN/HR

BOTTOM AREA 7600 FT

0.1348 CFS DESIGN INFIL. RATE CONVERTED TO CFS

Water Surface Storage Incremental Discharge Average Time AccumulatedSurface Volume Storage Discharge TimeSurface Volume Storage Discharge Time

Elevation (ft) (cu. Ft) Volume (Cu. Ft) (cfs) (cfs) (hrs) (hrs)378.00 12921 0.1348 0.00

6907 0.135 14.24376.50 6014 0.1348 14.24

6014 0.135 12.40375.00 0 0.1348 26.63

Therefore total dewatering time is 26.63 HRS= 1.11 DAYS

STORMWATER STRUCTURESTORMWATER STRUCTUREDEWATERING CALCULATIONS

DATE: 12/16/2016

BY: CMD

JOB NO.: 2731 PROJECT:DESCRIPTION: DEWATERING CALCULATION

TOWNSHIP: Kennett

INFILTRATION BED 2

PERC. RATE 3.663 IN/HR Hydraulic Conductivity Rate - Geometric Mean

Chatham Financial

2 Factor of SafetyDESIGN RATE 1.832 IN/HR

BOTTOM AREA 6250 FT

0.2650 CFS DESIGN INFIL. RATE CONVERTED TO CFS

Water Surface Storage Incremental Discharge Average Time AccumulatedWater Surface Storage Incremental Discharge Average Time AccumulatedSurface Volume Storage Discharge Time

Elevation (ft) (cu. Ft) Volume (Cu. Ft) (cfs) (cfs) (hrs) (hrs)376.00 9156 0.2650 0.00

9156 0.265 9.60373.50 0 0.2650 9.60

Therefore total dewatering time is 9.60 HRS= 0.40 DAYS

post construction stormwater management report

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Transcript of post construction stormwater management report