the erosion control bmp manualwcdpa.com/documents/thedrafterosioncontrolbmpmanual... · the erosion...

THE EROSION CONTROL

BMP MANUAL

What are the Major Changes?

A GUIDANCE DOCUMENT

►It was published in the PA Bulletin October 17, 2009

►There was a 60 day comment period

OVERALL LAYOUT

►Current Draft

Introduction

17 Chapters

12 Appendices

List of References

555 + pages (excluding cover & indices)

YOI!

INTRODUCTION

►Why is erosion & sediment pollution important?

CHAPTER 1: REQUIRED PLAN CONTENT

► Descriptions of the 15 Items listed in Chapter 102 expanded

1. Topographic Features

2. Soil Use Limitations

3. Proposed Alteration

4. Runoff

5. Receiving Surface Waters

6. Perimeter BMPs

7. Sequence (BMP installation & removal) on the plan drawings (not in narrative)



8. Supporting Calcs

9. Plan Drawings

10.Maintenance Program

11.Recycling & Disposal of Materials

12.Geologic or Soil Conditions that could cause pollution

13.Thermal impacts (in accordance with PCSM plan)



14.Consistency with PCSM plan

15.Riparian Forest Buffers identified

CHAPTER 2: BMP SEQUENCING

►Expanded to provide better guidance

►3 Standard Notes recommended for detail sheets

►Suggested Outline Provided

Exploration & Surveying►BMPs should be provided for disturbed areas

as well as surface water crossings (streams, wetlands, etc.)

May use the BMPs from Chapter 3

Others may be approved on case-by-case basis if found to be equal to or better than those in Chapter 3

BMP Ratings for use in Special Protection Watershed

►BMPs with low sediment removal efficiencies are not ABACTS

►BMPs with moderate sediment removal efficiencies are ABACTS for HQ watersheds, but not EV watersheds

►BMPs with high sediment removal efficiencies are ABACTS for HQ & EV watersheds

CHAPTER 3: SITE ACCESS

►Rock Construction Entrance – New detail

Rock Construction Entrance With Wash Rack

►ABACT for HQ & EV watersheds

Temporary & Permanent Access Roads

►Addressed for the 1st time


►Crowned Roadways


►Insloping

Waterbar►Brought out of the Pipeline text

Waterbar

►The detail has been enlarged & clarified

Broad-based Dip

►Broad-based Dips 2 details

Broad-based Dip

►Spacing Table provided

Road Grade

(Percent)

Spacing Between Dips, Culverts, or Deflectors (feet)

<2 300

3 235

4 200

5 180

6 165

7 155

8 150

9 145

10 140

OPEN-TOP CULVERTS

►Brought into the manual from the Timber Harvesting packet

WATER DEFLECTORS►May be used in lieu of

open-top culverts

ROADSIDE DITCH

►Brought into the manual from the Timber Harvesting packet

Need for lined Protective liners is addressed

DITCH RELIEF CULVERT►Brought back to the manual

DITCH RELIEF CULVERTTable 3.3 – Spacing of Temporary Culverts

Road Grade (%)

Culvert Spacing*

(ft)

Length of Upslope Drainage (ft)

< 300 300 –400

400 –500

500 –600

>600

Minimum Culvert Size (in)

2 300 12 15 15 15 18

3 235 12 15 15 15 18

4 200 12 15 15 15 18

5 180 12 12 15 15 15

6 165 12 12 12 15 15

7 155 12 12 12 12 15

8 150 12 12 12 12 15

9 145 12 12 12 12 15

10 140 12 12 12 12 15

12 135 12 12 12 12 15

*Culvert spacing may be adjusted slightly to take advantage of natural drainageways.

DITCH RELIEF CULVERTTable 3.4 – Spacing of Permanent Culverts

Road Grade

Soil Type in Ditch

Gravels, Sandy

Gravels, Aggregate Surfacing

Silty Gravels, Clayey Gravels

Plastic and Non-plastic Inorganic

Clays

Inorganic Silts, Silty or

Clayey Sands

Sands, Silty Sands, and

Gravelly Sands

Percent Feet

2 390 315 245 170 95

4 335 275 210 145 85

6 285 230 180 125 75

8 240 195 150 105 65

10 200 160 125 90 55

12 160 130 105 75 45

14 135 110 85 60 35

TURNOUTS

COMPOST SOCK SEDIMENT TRAP

►Addressed in this chapter to emphasize their usefulness in controlling runoff from access roads

►At entrances or where surface waters are in relatively close proximity to the access road

►An ABACT for HQ & EV watersheds

TEMPORARY STREAM CROSSINGS

►Should be avoided wherever possible

►Must be provided wherever construction equipment (including clearing and grubbing) must cross an existing stream channel

►Appropriate Chapter 105 permits must be obtained from DEP

►Designs must adhere to the conditions of

those permits


►Ford type crossings may not be used by construction equipment


►Temporary bridges are the preferred method of crossing


►Culvert Pipes

TEMPORARY WETLAND CROSSINGS

►Should be avoided wherever possible

►Must be minimized

TEMPORARY WETLAND CROSSINGS

►Figure 3.5

Typical Tire Mat Crossing

►Figure 3.6

Typical Expanded Metal Grating Crossing

►Figure 3.7

Typical Wood Mat Crossing

EARTHWORK WITHIN STREAM CHANNELS

►Excavations done from the top of banks

►Where it is not possible

Temporary crossing

Causeway


►Figure 3.9 Temporary bypass channel same as old Figure 33

A geotextile protective lining should be provided

Channel designed to pass normal base flows if the crossing will be completed in one to three days

Otherwise, channel must be designed for bank-full flow


►Figure 3.10 Temporary bypass pipe same as old Figure 34

Pipe sized so that the normal flow depth (d) is < ½ the diameter of the pipe (D)


►Figure 3.11 Pumped water bypass system revised to show filter bag for work area

►Also has following note:

“Pump intake shall be

maintained a sufficient

distance from bottom to

prevent sediment from

entering the system”


►Earthwork within stream channels

►Earthwork within lakes or ponds

Turbidity barriers




►Dewatering work areas

New detail for pumped water filter bags




►Dewatering work areas

New detail for pumped water filter bags

Detail provided for sump pits


►Site Housekeeping & Materials Management

Waste Management

Concrete Washouts

CHAPTER 4: SEDIMENT BARRIERS

►Brought back the alignment figure

►Compost Sock

►ABACT for HQ & EV watersheds

►Can be used in some locations where silt fence cannot

►8” & 9” socks for single lots only


►Max Slope Length Nomograph


►Compost Filter Berm

►ABACT for HQ but not EV


Compost Berm


►Weighted Sediment Filter Tubes

►ABACT for HQ but not EV


►Silt Fence

►Not an ABACT for HQ or EV

►Tolerance for support stakes

►8’ Setback

►Max Slope Length Nomograph for Silt Fence



►Minimum Silt Fence Fabric Properties are provided


►Super Silt Fence

►Not an ABACT for HQ or EV

►Posts must be installed with a post-hole drill

►Fiber Logs (wattles)

►Not an ABACT

►12” Logs may use Standard Silt Fence slope lengths

►18” Logs may use Reinforced Silt Fence slope lengths



►Wood Chip Berms

►ABACT for HQ, but not EV


►Straw Bale Barriers

►Not an ABACT

►Disallowed for projects lasting more than 3 months


►Vegetative Filter Strips

►ABACT for HQ (when used in conjunction with another BMP) but not EV

►Minimum width table provided

CHAPTER 4: INLET PROTECTION

►Inlet filter bags

►ABACT for HQ, not EV


►Stone Inlet Protection

►Not an ABACT unless compost layer provided (HQ, not EV)


►Alternate details for stone & mesh at grade


►Alternate details for stone & mesh not at grade

CHAPTER 5: RUNOFF CALCS

►Designers referred to NOAA’s website for up-to-date rainfall data

►Runoff coefficient table expanded to give more options

►New equations for calculating intensity

CHAPTER 5: RUNOFF CALCS

►Penn DOT’s updated tables, charts, & maps provided as an alternative method

CHANNELS

►New standard detail provided for vegetated channels

CHANNELS

►Equation provided to calculate Manning’s “n” for vegetated channels (Retardance C)

(n = 0.047 -0.4)

CHANNELS

►Tables provided for trapezoidal vegetated channel “n” values (Retardance C)

CHANNELS

►Standard detail provided for sodded channels

CHANNELS

►New standard detail provided for riprap channels

CHANNELS

►Guidance provided for design of riprap channels using shear stress

CHANNELS

►Nomograph for permissible flow depth of riprap channels (acceptable alternative to shear stress analysis)

CHANNELS

►Table for reno mattress & gabions revised

TOP-OF-SLOPE BERMS

►New standard detail provided for Top-of-slope Berms

TOP-OF-SLOPE BERMS

►Figure provided for maintaining Top-of-slope Berms as fills are built upward

CHAPTER 7: SEDIMENT BASINS

►Additional Design Criteria (Now 26)

Forebays and/or turbidity barriers may be substituted for 2:1 flow length:width ratio

Routing of peak flow from 25 yr/24 hr storm may be substituted for 2 cfs discharge capacity

Principal spillway must have capacity for 10 yr/24 hr storm

Some outlet barrels to be set in concrete cradle

PVC outlet barrels disallowed


►Additional Design Criteria

Guidance provided for discharge analyses

Limitations put on soils acceptable for use as embankment material (GC, GM, SC, SM, CL or ML )


►New skimmer detail provided


►Detail for skimmer attached to permanent riser provided


►Detail for stone landing for a skimmer provided


►Design chart for skimmer orifice revised


►Tables provided for outlet barrel capacity


►Standard cross-section has been revised


►Table provided for sizing concrete bases of risers


►Tables provided for sizing emergency spillway


►Figure provided to illustrate forebay


►Confusing chart for sizing anti-seep collars replaced with step-by-step guidance for calculating size & spacing of collars

►Typical details provided


►Figure provided to illustrate filter diaphragm


►Figure provided to illustrate concrete cradle

CHAPTER 8: SEDIMENT TRAPS

►Additional Design Criteria (Now 14)

Minimum surface area to be provided

Permanent facilities to meet standards of Stormwater BMP Manual

4:1 Flow length:width ratio for traps in special protection watersheds

Discharge requirements added


►Embankment Spillway Detail revised


►Table provided for sizing barrel/riser spillways


►Type M Inlet Trap Detail revised


►Detail provided for permanent riser with temporary holes

STEEP GRADIENT PIPES

►Slopes > 0.05 ft/ft

►Manning’s equation must be used

►For pipe with high anticipated velocities (>17.0 FPS), drop structures or other energy reducing structures to reduce velocity prior to discharge

MANNING’S EQUATION

SD

nV

3

2

4

486.1

where: V = Velocity in fps

D = Pipe diameter in feet

S = Pipe slope in ft/ft

MAX & MIN TAILWATER

►Disallowed for box culverts

GROUTING

► Grouting of riprap is not recommended for most installations

► Where riprap is grouted, the following applies:

1. Precautions must be taken to prevent uncured concrete from coming into contact with any surface waters

2. Grout must be placed in a layer with thickness equivalent to the d50 stone size over the entire extent of the apron prior to rock placement

3. After stone placement, void spaces shall be filled with grout

CHAPTER 9: OUTLET PROTECTION

►Detail provided for outfall without wingwalls


►Detail provided for discharge to existing channel


►Detail provided for transition flow mat


►Figure provided to illustrate drop inlet structure

CHAPTER 10: ON-LOT CONTROLS

► 3 Standard Details provided

CHAPTER 11: STABILIZATION

► Surface roughening techniques should be applied to slopes 3:1 and greater unless it can be shown that no potential for sediment pollution to surface waters

► Slopes within 50 feet of surface water should be blanketed if seeding is proposed as the means to achieving permanent stabilization

► Spray-on type blankets should be applied to roughened surfaces


►Table provided for various depths of topsoil application


►Table provided for application rates of soil amendments


►Guidance provided for Bonded Fiber Matrices and Flexible Growth Media

►Guidance provided for use of PAMs

►Guidance provided for sodding


►Guidance provided cellular confinement systems

CHAPTER 12: NEW PRODUCTS & PROCEDURES

►One requirement added:

Applicants should submit their request for approval (along with all pertinent drawings, details, supporting calculations, manufacturer’s recommendations, etc.) to the local Conservation District, the appropriate Regional DEP Office (Watershed Management), AND the Area Engineer responsible for the part of the state in which the project is located

ADDITIONAL CHAPTERS

►17 – Areas of Special Concern

Sinkhole Repair

ADDITIONAL CHAPTERS


Sinkhole Repair

Contaminated Sites

ADDITIONAL CHAPTERS


Sinkhole Repair

Contaminated Sites

Special Protection Watersheds

ADDITIONAL CHAPTERS


Sinkhole Repair

Contaminated Sites


Slope Failures

ADDITIONAL CHAPTERS


Sinkhole Repair

Contaminated Sites


Slope Failures

Geothermal Wells

APPENDICES

►A – Checklists

Complete Plan Checklist

Revised Technical Review Checklist

Expanded Technical Review Checklist

APPENDICES

►A – Checklists

►B – Standard Worksheets

APPENDICES

►A – Checklists


►C - Standard Plan Notes

Standard Notes placed on Plan Drawings

Optional Notes placed on drawings where appropriate

APPENDICES

►A – Checklists



►D – Standards for Maps & Drawings

APPENDICES

►A – Checklists




►E – Soil Use Limitations

If an X appears, go to the NRCS website for more info

APPENDICES

►A – Checklists





►F – Energy Dissipaters

APPENDICES

►A – Checklists





►F – Energy Dissipaters

►G- Structural Level Spreaders

APPENDICES

►H – Dust Control

APPENDICES


►I – Guide to Preserving Trees

APPENDICES



►J – Tree Planting

APPENDICES




►K – Water Well Drilling Fact Sheet

APPENDICES




►K – Water Well Drilling Fact Sheet

►L – Glossary

►References

QUESTIONS?

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