Pennsylvania Stormwater Best Management Practices Manual ...

Pennsylvania Stormwater

Best Management Practices

Manual

Chapter 6

Structural BMPs

363-0300-002 / December 30, 2006

Pennsylvania Stormwater Best Management Practices Manual

Chapter 6

Chapter 6

Structural BMPs

6.1

Introduction¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­1

6.2

Groupings of Structural BMPs¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­..1

6.3

Manufactured Products¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­..2

6.4

Volume/Peak Rate Reduction by Infiltration BMPs¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­.5

BMP 6.4.1

Pervious Pavement with Infiltration Bed¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­.¡­¡­7

BMP 6.4.2

Infiltration Basin¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­..27

BMP 6.4.3

Subsurface Infiltration Bed¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­...33

BMP 6.4.4

Infiltration Trench¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­.¡­41

BMP 6.4.5

Rain Garden / Bioretention¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­...49

BMP 6.4.6

Dry Well / Seepage Pit¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­.61

BMP 6.4.7

Constructed Filter¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­.¡­71

BMP 6.4.8

Vegetated Swale¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­.¡­..83

BMP 6.4.9

Vegetated Filter Strip¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­.¡­¡­..99

BMP 6.4.10 Infiltration Berm & Retentive Grading¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­.¡­¡­.113

.

Volume/Peak Rate Reduction BMPs¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­.¡­¡­...123

BMP 6.5.1

Vegetated Roof¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­.¡­¡­..125

BMP 6.5.2

Runoff Capture & Reuse¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­.¡­¡­¡­¡­¡­¡­¡­.139

6.5

6.6

Runoff Quality/Peak Rate BMPs¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­.¡­¡­...149

BMP 6.6.1

Constructed Wetland¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­.¡­151

BMP 6.6.2

Wet Pond/ Retention Basin¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­..163

BMP 6.6.3

Dry Extended Detention Basin¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­.¡­...173

BMP 6.6.4

Water Quality Filters & Hydrodynamic Devices¡­¡­.¡­¡­¡­¡­¡­..¡­..183

6.7

Restoration BMPs¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­..¡­189

BMP 6.7.1

Riparian Buffer Restoration. ¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­...191

BMP 6.7.2

Landscape Restoration¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­..¡­211

BMP 6.7.3

Soils Amendment & Restoration¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­.¡­....221

BMP 6.7.4

Floodplain Restoration¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­.¡­..¡­231

6.8

Other BMPs and Related Structural Measures¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­..¡­.¡­241

BMP 6.8.1

Level Spreader¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­¡­..¡­.¡­..243

BMP 6.8.2

Special Detention Areas ¨C Parking Lot, Rooftop¡­¡­¡­¡­..¡­¡­¡­.¡­.253

363-0300-002 / December 30, 2006

Pennsylvania Stormwater Best Management Practices Manual

Chapter 6

6.1 Introduction

Twenty-one Structural BMPs are listed and described in this chapter. As indicated in both Chapters 4

and 5, many of these ¡°structures¡± are natural system-based and include vegetation and soils

mechanisms as part of their functioning. More conventional ¡°bricks and mortar¡± structures are also

included in this chapter.

Several of the BMPs presented in this chapter lead to variations on a central them. The vegetated

swale is a good example of a core BMP that fosters numerous others. These variations have been

included in this chapter with some explanation and reference made as to how and when such variations

can be successfully applied. As lengthy as the list of Structural BMPs might be , many more BMPs are

expected to emerge as stormwater management practices continue to evolve and mature.

Each BMP is outlined using approximately the same structure or outline as has been applied to the

Non-Structural BMPs.

6.2 Groupings of Structural BMPs

Structural BMPs are grouped according to the primary, though not exclusive, stormwater functions, as

follows:

Volume/Peak Rate Reduction by Infiltration BMPs

Volume/Peak Rate Reduction BMPs

Runoff Quality/Peak Rate BMPs

Restoration BMPs

Other BMPs

In all cases, these stormwater functions are linked to the Recommended Site Control Guidelines

presented in Chapter 3. Most of the Structural BMPs fall into the category of Volume/Peak Rate

Reduction. Some of these BMPs also possess excellent water quality protection capabilities as well.

Volume and Peak Rate functions also can be provided by a smaller group of increasingly important

Structural BMPs such as Vegetated Roofs and Roof Capture/Reuse (e.g., rain barrels and cisterns).

Certain BMPs provide water quality and peak rate control functions, without any significant control of

volume. The Restoration BMPs and Other BMP categories provide a mix of stormwater functions.

Although these BMPs have not been frequently used in the past, they can offer real potential for many

Pennsylvania municipalities in the future.

Lastly, two special lists of instructions, or Protocols, have been developed specifically for use with all

infiltration-oriented structural BMPs and are presented in Appendix C.

Protocol 1: Site Evaluation and Soil Infiltration Testing

Protocol 2: Infiltration Systems Design and Construction Guidelines

These Protocols should be followed whenever infiltration-oriented BMPs are being developed. The

Protocols set forth a variety of actions common to all infiltration BMPs. These actions should be taken

to ensure that proper site conditions and constraints are being addressed, proper design considerations

are being taken, and proper construction specifications are being integrated into the overall design of

the BMP. An especially important aspect of these instructions focuses on full and careful testing of the

soil, thereby necessitating a separate Protocol that addresses soil testing and analysis. If these

Protocols are followed, the risk of failed infiltration BMPs will be minimized, if not eliminated.

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Pennsylvania Stormwater Best Management Practices Manual

Chapter 6

One of the most challenging technical issues considered in this manual involves the selection of BMPs

with a high degree of pollutant reduction or removal efficiency. The Non-Structural BMPs described in

Chapter 5 and the Structural BMPs presented in Chapter 6 are all rated in terms of their pollutant

removal performance or effectiveness. The initial BMP selection process analyzes the final site plan

and estimates the potential pollutant load, using Appendix A. The targeted reduction percentage for

representative pollutants (such as 85% reduction in TSS and TP load and 50% reduction in the solute

load) is achieved by a suitable combination of Non-Structural and Structural BMPs. This process is

described in more detail in Chapter 8.

6.3 Manufactured Products

A variety of product suppliers, distributors, and manufacturers have provided extensive product

information to PADEP during the preparation of this manual. Many of these products can be used in

conjunction with the Non-Structural BMPs set forth in Chapter 5 as well as the Structural BMPs

presented in this chapter. The proper application and use of many of these manufactured products can

further the stormwater management goals and objectives of this manual. It should be noted that

Pennsylvania does not have an established product review and testing function. The interested

reader/user is directed to the following sources to learn about the performance of a specific product or

technology:

The Technology Acceptance Reciprocity Partnership (TARP) ¨C A partnership of the states of

California, Illinois, Maryland, Massachusetts, New Jersey, New York, Pennsylvania and Virginia

that establishes standardized methods to guide the collection and evaluation of new and

innovative technology performance across the states. Information is available at:

dep.state.pa.us/dep/deputate/pollprev/techservices/tarp/index.htm

Environmental Technology Evaluation Center (EvTEC) of The Civil Engineering Research

Foundation (CERF), including their Stormwater Best Management Practices (BMPs) Verification

Program - information available at &



U.S. EPA's Environmental Technology Verification Program (ETV) - information available at



The University of New Hampshire's Center for Stormwater Technology Evaluation and

Verification (CSTEV) - information available at

The Chesapeake Bay Program's Innovative Technology Task Force (ITTF) - information about

the program as well as many useful links to other programs available at



New Jersey's Energy and Environmental Technology Verification Program - results available

through the New Jersey Corporation for Advanced Technology (NJCAT) at

Disclaimer: The technology descriptions contained in this document including, but not limited to,

information on technology applications, performance, limitations, benefits, and cost, have been

provided by vendors. No attempt was made to examine, screen or verify company or technology

information. The Pennsylvania Department of Environmental Protection has not confirmed the

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Pennsylvania Stormwater Best Management Practices Manual

Chapter 6

accuracy or legal adequacy of any disclosures, product performance, or other information

provided by the companies appearing here. The inclusion of specific products in this document

does not constitute or imply their endorsement or recommendation by the Pennsylvania

Department of Environmental Protection.

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