FJ_LDH_Part_II.pdf

When and Where to Use It

Installation:

Inspection and Maintenance:

Land Disturbance Handbook

Fort Jackson

Land Disturbance Handbook

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APPENDIX F

PERMANENT VEGETATION GUIDANCE

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Fort Jackson’s Seeding Specifications are included in Chapter 2, Section 2.3: Requirements for

Routine Activities and Maintenance.

For further guidance, reference SCDOTs Seeding Specifications at http://www.scdot.org/doing/stormwater_Erosion.aspx.

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APPENDIX G

BMP USAGE GUIDANCE

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EROSION PREVENTION BMP SUGGESTED USES

BMP

Slope

Protection

Waterway

Protection

Surface

Protection

Enclosed

Drainage

Large Flat

Areas

Borrow

Areas

Adjacent

Properties

Erosion Prevention Measures X X X X X X X

Surface Roughening X X

Bench Terracing X X

Temporary Seeding X X X X X

Mulching X X X

Erosion Control Blankets and Turf

Reinforcement Mats X X X X

Final Stabilization X X X X

Permanent Seeding and Planting of Grasses X X X X

Permanent Ground Cover Plants X X X

Sodding X X X X

Riprap or Aggregate X X X

Outlet Protection X X X

Dust Control X X X

Polyacrylamide (PAMs) X X X X X X

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TEMPORARY SEDIMENT CONTROL BMP SUGGESTED USES

BMP

Slope

Protection

Waterway

Protection

Surface

Protection

Enclosed

Drainage

Large Flat

Areas

Borrow

Areas

Adjacent

Properties

Temporary Sediment Control Structures X X X X X X X

Storage Volumes and Maintenance Schedules X X X

Temporary Sediment Basin X X X X

Multipurpose Basin X X .X X

Temporary Sediment Trap X X X

Silt Fence X X X

Rock Ditch Check X X

Stabilized Construction Entrance X X

Storm Drain Inlet Protection X X X

Vegetated Filter Strips X X

Rock Sediment Dike X X X

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RUNOFF CONTROL AND CONVEYANCE BMP SUGGESTED USES

BMP

Slope

Protection

Waterway

Protection

Surface

Protection

Enclosed

Drainage

Large Flat

Areas

Borrow

Areas

Adjacent

Properties

Pipe Slope Drains X X

Temporary Stream Crossing X X X

Runoff Conveyance Measures X X X

Construction De-watering X X X X

Level Spreader X X X

Subsurface Drains X X

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STRUCTURAL STORMWATER QUALITY BMP SUGGESTED USES

BMP

Land

Requirement Single

Family

Multi

Family

Low Density

Commercial

High Density

Commercial

Low Density

Industrial

High Density

Industrial

Wet Storm Water Ponds

MODERATE

- HIGH X X X X X X

Wet Extended Pond

MODERATE

- HIGH X X X X X X

Micropool Extended Pond

MODERATE

- HIGH X X X X

Shallow Wetland

MODERATE

- HIGH X X X X

Extended Detention Shallow

Wetland

MODERATE

- HIGH X X X X

Pond/Wetland System

MODERATE

- HIGH X X X X

Pocket Wetland MODERATE X X X X

Bioretention Areas MODERATE X X X X X X

Sand Filtration Facilities LOW X X X X

Infiltration Trenches MODERATE X X X X X X

Enhanced Dry Swales HIGH X X X X

Pre-Fabricated Control Devices LOW X X X X X

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STRUCTURAL STORMWATER QUALITY BMP CHARACTERISTICS

BMP

Maintenance

Burden Costs

Aesthetically

Pleasing

Provide

Habitat

Drainage Area

(Acres) Soils

Wet Storm Water Pond LOW LOW X X

10 MIN

25 PREFERRED

HSG A SOILS

MAY REQUIRE

POND LINER

Wet Extended Pond with

Aquatic Bench LOW LOW X X

10 MIN

25 PREFERRED

HSG B SOILS

MAY REQUIRE

Micropool Extended Pond MODERATE LOW X X 10 MIN

INFILTRATION

TESTING

Shallow Wetland MODERATE MODERATE X X 20 MIN

Extended Detention Shallow

Wetland MODERATE MODERATE X X 20 MIN

HSG A AND B SOILS

MAY REQUIRE

Pond/Wetland System MODERATE MODERATE X X 20 MIN

LINER

Pocket Wetland HIGH MODERATE X X 5 MIN

Bioretention Areas LOW MODERATE X X 5 MAX

CLAY OR SILTY

SOILS MAY

Sand Filtration Facilities HIGH HIGH

5 MAX

2 PREFFERED

REQUIRE

PRETREATMENT

Infiltration Trenches HIGH HIGH 5 MAX

INFILTRATION

RATE > 0.5 IN/HR

Enhanced Dry Swales LOW MODERATE 5 MAX PERMEABLE SOIL

Pre-Fabricated Control Devices HIGH HIGH X (HIDDEN) VARIES NO REQUIREMENT

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STRUCTURAL STORMWATER QUALITY BMP SUGGESTED USES

BMP

Water

Quality

Channel

Protection

Flood

Protection

TSS

Removal

Nutrient

Removal

Metal

Removal Bacterial

Removal

Wet Stormwater Pond X X X HIGH MODERATE MODERATE MODERATE

Wet Extended Pond with

Aquatic Bench X X X HIGH HIGH MODERATE MODERATE

Micropool Extended Pond X X X HIGH MODERATE MODERATE NO DATA

Shallow Wetland X X X HIGH HIGH MODERATE HIGH

Extended Detention Shallow

Wetland X X X HIGH HIGH MODERATE HIGH

Pond/Wetland System X X X HIGH HIGH MODERATE HIGH

Pocket Wetland X X HIGH HIGH MODERATE HIGH

Bioretention Areas X HIGH MODERATE MODERATE NO DATA

Sand Filtration Facilities X HIGH MODERATE MODERATE MODERATE

Infiltration Trenches X HIGH MODERATE HIGH HIGH

Enhanced Dry Swales X HIGH MODERATE MODERATE LOW

Pre-Fabricated Control Devices X HIGH LOW-HIGH LOW-HIGH LOW-HIGH

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APPENDIX H

Contractor Certification Form

CONTRACTOR CERTIFICATION FORM

For Coverage(s) Under South Carolina

NPDES General Permit For Stormwater Discharges From Construction Activities SCR100000

(Maintain As Part of On-Site SWPPP)

Date: ______________________

A. Project Information

1. NPDES Coverage No.: SCR _________________ State Permit (Tracking) No.: ___________________

2. Project/Site Name (As Approved by Department): ________________________________________________________________

3. Owner/Operator Name: _________________________________________________________________________________

B. Contractor Information

1. Name: _____________________________________________ Title/Position: ____________________________________

Mailing Address: ____________________________ City: _____________________State: ______Zip: _________ Company Name (As Applicable): ____________________________________________________________________________

Phone: _______________________ Email Address: ___________________________________________________________

2. Describe Construction-Related Responsibilities & Activities (Home construction, site grading, utility line installation, etc.):

C. Contractor Certification Statements & Agreement: (Read the Contractor Certification statements below (in entirety) and provide date and signature of agreement below). See Section 122.22 of S.C. Reg. 61-9 for signatory authority requirements. DO NOT SIGN IN BLACK INK!

“I certify by my signature below that I or I (on behalf of my company and its contractors and agents), as the case may be,

(a) Understand, accept, and will adhere to the provisions of the Stormwater Pollution Prevention Plan (SWPPP) as it pertains to the portion of the project I am or my company is responsible for, and as required by the coverage under the National Pollutant Discharge Elimination System (NPDES) General Permit for Stormwater Discharges From Construction Activities SCR100000 issued to the Owner/Operator of the construction activity with whom I am or my company is under contract to perform construction related professional services;

(b) Am legally accountable to the SC Department of Health and Environmental Control (DHEC), under the authorities of the Clean Water Act and the SC Pollution Control Act, to ensure compliance with the terms and conditions of the SWPPP applicable to my or my company’s portion of the project;

(c) Must comply with the terms and conditions of the Construction General Permit (CGP), will adhere to applicable standards and stormwater erosion control practices established in the SWPPP and in the Best Management Practices (BMP) manual at all times while performing work at the project site, and agree to implement corrective actions identified by the qualified inspector during a site inspection; and

(d) Understand that DHEC enforcement actions may be taken against any specific or combination of permittees and contractors if the terms and conditions of the SWPPP are not met.

Therefore, having understood the above information, I am signing this certification as contractor to the aforementioned NPDES general permit.”

Printed Name of Contractor Title/Position

Signature of Contractor Date Signed

Termination of Contractor Certification Agreement: DO NOT SIGN IN BLACK INK!

(When your land-disturbing activities at this site have been completed, sign and date below). After this date, you may not perform any land-disturbing activities at this site unless you sign a new contractor certification agreement).

Signature of Contractor Date Signed

DHEC 0437 (10/2012)

CONTRACTOR CERTIFICATION FORM

NPDES Coverage No.: SCR ___________________ State Permit (Tracking) No.: ____________________ Project/Site Name: __________________________________________________________________________________

C. Contractor Certification Statements:

All contractors performing any land disturbing activity at a construction site must be certified and listed in the On-Site SWPPP (OS-SWPPP) in order to work on the site. Read the Certification statements below (in entirety) and provide date and signature of agreement below.

“I certify by my signature below that I or I (on behalf of my company and its contractors and agents), as the case may be,

(a) Understand, accept, and will adhere to the provisions of the Stormwater Pollution Prevention Plan (SWPPP) as it pertains to the portion of the project I am or my company is responsible for, and as required by the coverage under the National Pollutant Discharge Elimination System (NPDES) General Permit for Stormwater Discharges From Construction Activities SCR100000 issued to the Owner/Operator of the construction activity with whom I am or my company is under contract to perform construction related professional services;

(b) Am legally accountable to the SC Department of Health and Environmental Control (DHEC), under the authorities of the Clean Water Act and the SC Pollution Control Act, to ensure compliance with the terms and conditions of the SWPPP applicable to my or my company’s portion of the project;

(c) Must comply with the terms and conditions of the Construction General Permit (CGP), will adhere to applicable standards and stormwater erosion control practices established in the SWPPP and in the Best Management Practices (BMP) manual at all times while performing work at the project site, and agree to implement corrective actions identified by the qualified inspector during a site inspection; and

(d) Understand that DHEC enforcement actions may be taken against any specific or combination of permittees and contractors if the terms and conditions of the SWPPP are not met.

Therefore, having understood the above information, I am signing this certification as contractor to the aforementioned NPDES general permit.”

C. CONTRACTOR CERTIFICATION AGREEMENTS

(Sheet 1)

NPDES Coverage No.: SCR ________________ State Permit (Tracking) No.: ______________________ Project/Site Name: __________________________________________________________________________________

Please print legibly and complete all spaces on the form. If you are an approved Blanket Utility Provider, you do not need to sign this form, but you must submit a copy of your Annual Blanket NOI registration information to the Owner/Operator. Abbreviate if necessary and submit the completed form to the Owner/Operator. (When your land-disturbing activities at this site are complete, sign and date the termination agreement below. After this date, you may not perform any land-disturbing activities at this site unless you sign a new contractor certification agreement). Additional certification agreement pages may be attached as necessary. DO NOT SIGN IN BLACK INK!

Contractor Information:

Name: _____________________________________________ Title/Position: ______________________________________

Company Name (As Applicable) _____________________________________________________________________________

Mailing Address: ______________________________________ City: __________________ State: ____ Zip: _______________

Phone: _________________________ Email Address: ___________________________________________________________

Contractor Certification (Signature of Agreement): Provide date and signature. DO NOT SIGN IN BLACK INK!

Signature of Contractor Date Signed

Termination of Contractor Certification Agreement: Provide date and signature. DO NOT SIGN IN BLACK INK!

Signature of Contractor Date Signed

Contractor Information:

Name: _____________________________________________ Title/Position: ____________________________________

Company Name (As Applicable) _____________________________________________________________________________

Mailing Address: ______________________________________ City: __________________ State: ____ Zip: _______________

Phone: _________________________ Email Address: ___________________________________________________________

Contractor Certification (Signature of Agreement): Provide date and signature. DO NOT SIGN IN BLACK INK!

Signature of Contractor Date Signed

Termination of Contractor Certification Agreement: Provide date and signature. DO NOT SIGN IN BLACK INK!

Signature of Contractor Date Signed

Contractor Information:

Name: _____________________________________________ Title/Position: ____________________________________

Company Name (As Applicable) _____________________________________________________________________________

Mailing Address: ______________________________________ City: __________________ State: ____ Zip: _______________

Phone: _________________________ Email Address: ___________________________________________________________

Contractor Certification (Signature of Agreement): Provide date and signature. DO NOT SIGN IN BLACK INK!

Signature of Contractor Date Signed

Termination of Contractor Certification Agreement: Provide date and signature. DO NOT SIGN IN BLACK INK!

C. CONTRACTOR CERTIFICATION AGREEMENTS

(Company Certifications)

(Sheet 2)

Use this sheet for certification agreements of contractors, subcontractors, etc. employed by the Contracting Company identified below

ONLY. If you do not work for the company listed below, do not sign this sheet. If you are an approved Blanket Utility Provider, you do not need to sign this form, but you must submit a copy of your Annual Blanket NOI registration information to the Owner/Operator.

Abbreviate if necessary and submit the completed form to the Owner/Operator. (When your land-disturbing activities at this site are complete, sign and date the termination agreement below. After this date, you may not perform any land-disturbing activities at this site unless you sign a new contractor certification agreement). Additional certification agreement pages may be attached as necessary. Please print legibly and complete all spaces on the form. DO NOT SIGN IN BLACK INK!

NPDES Coverage No.: SCR ________________ State Permit (Tracking) No.: ______________________ Project/Site Name: __________________________________________________________________________________

Contracting Company Information:

Company Name _______________________________________________________________________________________________

Mailing Address: __________________________________________ City: __________________ State: ______ Zip: _______________

Phone: ___________________________ Email Address: _______________________________________________________________

Contractor Information:

Contractor Name: _______________________________________ Title/Position: ____________________________________

Contractor Certification (Signature of Agreement): Provide date and signature. DO NOT SIGN IN BLACK INK!

Signature of Contractor Date Signed

Termination of Contractor Certification Agreement: Provide date and signature. DO NOT SIGN IN BLACK INK!

Signature of Contractor Date Signed

Contractor Name: _______________________________________ Title/Position: ____________________________________

Contractor Certification (Signature of Agreement): Provide date and signature. DO NOT SIGN IN BLACK INK!

Signature of Contractor Date Signed

Termination of Contractor Certification Agreement: Provide date and signature. DO NOT SIGN IN BLACK INK!

Signature of Contractor Date Signed

Contractor Name: _______________________________________ Title/Position: ____________________________________

Contractor Certification (Signature of Agreement): Provide date and signature. DO NOT SIGN IN BLACK INK!

Signature of Contractor Date Signed

Termination of Contractor Certification Agreement: Provide date and signature. DO NOT SIGN IN BLACK INK!

Instructions for Completing the Contractor Certification Form If you are uncertain whether you need to obtain coverage under the NPDES General Permit for Stormwater Discharges From Construction Activities SCR100000 (CGP), if you cannot access the websites listed in these instructions, or if you have any questions, contact the Bureau of Water Stormwater Permitting Section at (803) 898-4300 or the Coastal Stormwater Permitting Section at (843) 953-0200. Please see the Bureau of Water, Stormwater Permitting website (http://www.scdhec.gov/stormwater) for guidance and additional information.

DHEC 0437 (10/2012)

Who Must Complete a Contractor Certification Form

Contractors (who are not Permittees or Annual Blanket Utility providers), employed by a Primary or Secondary Permittee of a construction project or site, must complete a Contractor Certification Form before performing any land-disturbing activities at the construction site. Contractor Certification Forms do not require Department approval, however, this form must be signed, dated, and submitted by each contractor to the Owner/Operator prior to commencement of land-disturbing activities by the contractor.

General Guidance for this Form

Are there Other Requirements for Contractors Completing this form?

Contractors completing this form must also attend a pre-construction conference, and sign and date a Pre- Construction Conference Certification Agreement for each project or construction site where they will be performing construction activities. Contractors cannot work at a construction site until they sign this certification form and document attendance at the Pre- Construction Conference held for the project or construction site. See Section 4.1 of the 2012 CGP for additional information.

What Does This Certification Mean?

Upon signing this certification, the contractor is accountable to DHEC to ensure the terms and conditions of the approved Stormwater Pollution Prevention Plan (developed for the respective construction project or site) and the Construction General Permit (CGP) are implemented and adhered to in the respective area(s) of the plan where each contractor and/or company signing this form will be performing work. Each contractor becomes subject to DHEC enforcement actions if permit conditions are not met. See Sections 2.2.3 and 2.3.2 of the 2012 CGP for additional information.

Should the Owner/Operator Retain This Form?

The Owner/Operator of the construction site must retain completed Contractor Certification Forms with the approved On-Site SWPPP. This form must be retained for at least three years from the date permit coverage expires or is terminated.

Instructions for Completing this Form

Please print legibly and complete all spaces on the form. Abbreviate if necessary to stay within the space allowed for each item and submit the completed form to the Owner/Operator for the specific project or construction site listed in Section A.

Section A - Project Information Provide all requested information. Enter the date, NPDES coverage number, and Tracking No. provided by the Department for the approved SWPPP. Enter the official or legal name of the project or site, as approved by the Department. If this project is for an individual lot or group of lots, provide the lot number(s). Provide the name of the Owner/Operator.

Section B –Contractor Information Provide your legal name and title/position. As applicable, provide the legal (formal) name of the company, firm, public organization, or any other entity (you are employed by or represent) on whose behalf you will be performing contractor construction activities. Provide your mailing address, telephone and e-mail address. Briefly describe construction-related duties and responsibilities you or your company will perform for this project at the construction site.

Section C – Contractor Certification Statements & Agreement Read the certification statements (in entirety). Provide your printed name and title or position. Date and sign the certification agreement. Return the signed and dated form to the Owner/Operator. DO NOT SIGN IN BLACK INK. Sheets 1 and 2 are formatted for multiple contractor signatures. Sheet 2 is ONLY for signatures within a specific company. Each may be copied as necessary. Sign and date the Termination of Contractor Certification Agreement when the services you provide for this project are complete.

Return the signed and dated form to the Owner/Operator for record retention as a part of the On-Site SWPPP (OS-SWPPP).

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APPENDIX I

FORT JACKSON HAZARDOUS MATERIAL WASTE

MANAGEMENT PLAN

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APPENDIX J

SEDIMENT BASIN DESIGN INSTRUCTIONS

FLOATING SKIMMER

& BAFFLE SEDIMENT BASIN

DESIGN GUIDLEINES

FORT JACKSON, SOUTH CAROLOINA

May, 2013

May 2013 Fort Jackson Sediment Page 1

Basin Design Instructions

Table of Contents

1.0 INTRODUCTION

2.0 DESCRIPTION

3.0 SITE ASSESSMENT

4.0 DESIGN REQUIREMENTS

4.1 GENERAL DESIGN REQUIREMENTS

4.2 SAFETY

5.0 FORT JACKSON TEMPORARY FLOATING SKIMMER &BAFFLE SEDIMENT BASIN DESIGN

5.1 TEMPORARY FLOATING SKIMMER &BAFFLE SEDIMENT BASIN DESIGN AIDS

5.2 TEMPORARY RISER AND SPILLWAY DESIGN

6.0 PERMANENT MULTIPURPOSE FLOATING SKIMMER &BAFFLE SEDIMENT BASIN DESIGN

6.1 OPTION A (PEAK FLOW CONTROL DURING CONSTRUCTION REQUIRED)

6.2 OPTION B (PEAK FLOW CONTROL DURING CONSTRUCTION NOT REQUIRED)

6.3 FOREBAYS

6.3.1 DRY PERMANENT MULTIPURPOSE BASIN FOREBAYS

6.3.2 WET PERMANENT MULTIPURPOSE BASIN FOREBAYS

7.0 CONSTRUCTION

7.1 EQUIPMENT

7.2 INSTALLATION REQUIREMENTS

7.3 SITE WORK

7.4 TEMPORARY AND PERMANENT SEDIMENT CONTROL BASINS

7.5 EARTH DAM EMBANKMENT

7.6 AGGREGATE DIAPHRAGM OR ANTI SEEP COLLARS

7.7 AGGREGATE DIAPHRAGM OR ANTI SEEP COLLARS

7.8 EMERGENCY SPILLWAY

7.9 PRIMARY RISER SPILLWAY AND OUTLET BARREL

7.10 FLOATING SKIMMER

7.11 BAFFLES

7.12 SEDIMENT CLEANOUT STAKE

8.0 INSPECTION AND MAINTENANCE

9.0 REMOVAL

10.0 ACCEPTANCE

ATTACHMENT 1

ATTACHMENT 2

ATTACHMENT 3

ATTACHMENT 4

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FORT JACKSON FLOATING SKIMMER & BAFFLE

SEDIMENT BASIN DESIGN GUIDELINES

1.0 INTRODUCTION

These Floating Skimmer & Baffle Sediment Basin Design Guidelines are developed to provide guidance in designing Sediments Basins that incorporate floating skimmers, baffles, and surface withdrawal at Fort Jackson, South Carolina and includes design guidelines, Design Aids, and design details.

These Design Guidelines includes the following:

Appropriate Floating Skimmer & Baffle Sediment Basin Design Methodology.

NEW Graphical Design Aids(based on SEDIMOT modeling) specific to soils found at Fort

Jackson which incorporate Floating Skimmers and Baffles to design Sediment Basins for minimum 80% trapping efficiency.

Design of Floating Skimmer and Baffle Sediment Basins that will be Multipurpose Basins used for post construction water quality and quantity control including the design of

Forebays.

2.0 DESCRIPTION

Provide a Floating Skimmer & Baffle Sediment Basin to remove sediment from construction site runoff. A Floating Skimmer & Baffle Sediment Basin is a Basin where sediment-laden runoff is temporarily detained, allowing sediment to settle out before the runoff is discharged. The purpose of a Floating Skimmer & Baffle Sediment Basin is to collect and store sediment from disturbed areas cleared or graded during construction. To maximize effectiveness, locate

Floating Skimmer & Baffle Sediment Basins at the lowest points or near the edge of a watershed catchment.

Floating Skimmer & Baffle Sediment Basins include Baffles across the width of the Basin to spread flow across the entire width of the Basin reducing the potential for turbid flow and short circuiting. These Baffles may consist of Porous Baffle materials or Class A or B riprap.

Traditional temporary Sediment Basin designs typically used a perforated riser or staged riser with a low flow orifice for dewatering. This Specification utilizes dewatering from the water surface where the density of total suspended solids (TSS) is at a minimum in the water column.

A Floating Skimmer & Baffle Sediment Basin implements three spillway devices:

1. A Primary Riser Spillway consisting of a solid circular concrete monolithic base or extended base riser with no staged discharges or low flow orifices connected to an Outflow Barrel.

Stormwater enters the Primary Riser spillway by overtopping the structure and through a

Floating Skimmer.

May 2013 Fort Jackson Sediment Page 3

2. A Floating Skimmer attached to the bottom of the Primary Riser dewatering the runoff volume below the top elevation of the Primary Riser. The Floating Skimmer dewaters the volume below the Primary Riser in a time period ranging between 24 to 72 hours.

3. A stabilized Emergency Spillway that safely passes the 100-year 24-hr storm event with a minimum 1.0-foot of freeboard from the 100-year 24-hour water surface elevation to the top of the dam.

3.0 SITE ASSESSMENT

Select Floating Skimmer & Baffle Sediment Basin locations during a site evaluation, or by reviewing a detailed topographic map. Note natural watershed catchments and select Floating

Skimmer & Baffle Sediment Basin locations so runoff from land disturbing activities can easily be diverted into the Floating Skimmer & Baffle Sediment Basin. Install Floating Skimmer &

Baffle Sediment Basins before land disturbance activities begin.

Consider construction phasing when selecting locations for Floating Skimmer & Baffle Sediment

Basins. Select a location that allows the Temporary or Multipurpose Floating Skimmer & Baffle

Sediment Basin to remain in service as long as possible before final stabilization is achieved.

Select locations that are accessible for periodic sediment removal and other necessary maintenance. Identify locations for sediment disposal as part of the Temporary or Multipurpose

Floating Skimmer & Baffle Sediment Basin site selection. Identify sediment disposal locations on the Plans or as directed by the Engineer.

4.0 DESIGN REQUIREMENTS

Design Temporary Floating Skimmer & Baffle Sediment Basins that do not require peak flow reduction to pre-development conditions with no perforations in the Primary Riser structure.

Design permanent Multipurpose Floating Skimmer & Baffle Sediment Basins requiring peak flow reduction to keep the 2-year 10-year (25-year if required) 24-hour storm disturbed-state peak flow rates from the Basin less than or equal to the pre-disturbance peak flow rates with orifices and weirs incorporated into the Primary Riser structure. Ensure that all Multipurpose

Floating Skimmer & Baffle Sediment Basins are designed to meet any post-construction water quality requirements if required.

4.1 GENERAL DESIGN REQUIREMENTS

Use Temporary or Multipurpose Floating Skimmer & Baffle Sediment Basins on sites where 10 or more acres are disturbed and drain to a single point. Do not install Temporary or Multipurpose

Floating Skimmer & Baffle Sediment Basins in Waters of State designated by a solid or dashed blue line on USGS 7.5 minute quadrangle maps). Utilize Temporary Floating Skimmer & Baffle

Sediment Basins until the contributing flow areas to the basin have undergone final stabilization.

The design requirements outlined in this Specification must ensure a minimum of 80% trapping efficiency of total suspended solids (TSS).

May 2013 Fort Jackson Sediment Page 4

Ensure Temporary or Multipurpose Floating Skimmer & Baffle Sediment Basins adhere to the following requirements:

Drainage Area: 5 acre minimum, 100 acre maximum.

Drainage Area: 10 acres or more draining to one location requires a Floating Skimmer &

Baffle Sediment Basin.

Minimum 80 percent design removal efficiency for TSS.

Sediment storage volume accounted for in the overall design volume of the sediment basin.

Do not incorporate side slopes steeper than 3H:1V where applicable.

Optimum Basin length to width ratio is 2L:1W.

Temporary Basin bottom slope of 0.5%.

Permanent Dry Multipurpose Basins final Basin bottom slope of 2%.

Anti-vortex device / trash rack required for Primary Riser.

Floating Skimmer with minimum dewatering time of 24 hours and maximum dewatering time of 72 hours. (See Attachment 1 for Floating Skimmer requirements)

Minimum of 1 row of Baffles installed in the Basin. (See Attachment 2 for Porous Baffle requirements)

At least one row of Baffles placed between the Primary Riser structure and all pipes or channels discharging into the Basin.

Minimum embankment width at the top of the dam is 8 feet.

Antiseep collars required on all penetrations through the dam.

Perform temporary stabilization by seeding and install Temporary Erosion Control Blankets on exposed basin side slopes.

4.2 SAFETY

Follow the safety design criteria such as those outlined by the USDA Soil Conservation Service

(previously the Natural Resources Conservation Service), U.S. Army Corps of Engineers, and the Dam Safety.

Incorporate all possible safety precautions such as signs and fencing for permanent Multipurpose

Basins that are readily accessible to populated areas. Ensure the inside pond slopes are no steeper than 3H:1V where applicable. A safety fence or vegetative barrier is required where a permanent

Multipurpose Basins interior side slopes are steeper than 3H:1V or when the impoundment is a wall greater than 24 inches in height. If the wall is adjacent to a walkway or street a railing may be required instead of a fence.

May 2013 Fort Jackson Sediment Page 5

5.0 FORT JACKSON TEMPORARY FLOATING SKIMMER &BAFFLE SEDIMENT BASIN

DESIGN

Design Temporary Floating Skimmer & Baffle Sediment Basins using the following strategies.

1. Use the Design Aids provided in the Attachment 3 of this document.

2. In accordance to the requirements in standards for Stormwater Management and Sediment

Reduction Act 72-300 using Sedimot, SEDCAD4, Pond Pack, SEDPRO and other computer models that utilize eroded particle size distributions and calculates a corresponding 80% trapping efficiency for TSS.

5.1 TEMPORARY FLOATING SKIMMER &BAFFLE SEDIMENT BASIN DESIGN AIDS

For true Temporary Floating Skimmer & Baffle Sediment Basins:

1. Utilize a Temporary sediment basin non-perforated Primary Riser configuration.

2. Design a Primary Riser consisting of a solid circular concrete monolithic base or extended base riser with no staged discharges or low flow orifices.

3. Design the Basin so stormwater runoff enters the Primary Riser by overtopping the riser structure and through a Floating Skimmer.

4. Design the Primary Riser with a Floating Skimmer attached to the bottom of the riser dewatering the runoff volume below the top elevation of the riser in a time period ranging between 24 to 72 hours.

5. Provide calculations or Design Aids showing that this Basin will meet a minimum 80% TSS trapping efficiency.

6. Provide a minimum of 1 row of Baffles in the Basin. Place a minimum of 1 row of Baffles between the riser structure and all pipes or channels discharging to the Basin. Designers may use 0% dead space when using Baffles.

7. Design a stabilized Emergency Spillway that safely passes the 100-year 24-hr storm event with a minimum 1-foot freeboard from the 100-year 24-hour water surface elevation to the top of the dam.

5.2 TEMPORARY RISER AND SPILLWAY DESIGN

1. The Primary Riser consists of a solid circular concrete monolithic base or extended base riser with no low flow orifice or staged orifice/weir discharges. Runoff only enters the Primary

Riser structure by overtopping and through the Floating Skimmer.

2. Design the 10-year 24-hour storm event peak stage in the Basin at a maximum elevation of approximately 6 inches above the top elevation of the Primary Riser.

3. Design the Primary Riser and Outlet Barrel to operate in weir flow control and transition to pipe/barrel flow control. Orifice flow of the Primary Riser structure is not allowed for the

10-year 24-hour storm event.

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4. Minimum 1.5-foot elevation difference from the top of riser to the crest of the emergency spillway.

5. Design the Emergency Spillway to safely pass the peak runoff from the 100-year 24-hour storm event storm with a minimum 1.0-foot of freeboard between the 100-year peak water surface elevation and the top of the Emergency Spillway. Design the Emergency Spillway as a run-around conveyance that is constructed on existing ground and not over the Basin

Dam/Embankment.

6. Show all Basin dimensions and slopes on the Plans.

6.0 PERMANENT MULTIPURPOSE FLOATING SKIMMER &BAFFLE SEDIMENT

BASIN DESIGN

The Primary Riser spillway configuration for Permanent Multipurpose Basins used for both during construction sediment control and post construction water quality and quantity control for peak flow rate reduction contains orifices/weirs in the Primary Riser Structure.

6.1 OPTION A (PEAK FLOW CONTROL DURING CONSTRUCTION REQUIRED)

1. Design and utilize one Permanent Riser and outlet barrel configuration for both phases of the project that is based on post-construction water quality and quantity control.

a. This ensures that there is no damage or introduction of a point of structural weakness to the primary riser, outflow barrel and permanent dam structure as a result of installing a temporary riser, removing it, and then installing a permanent riser. Maintaining the structural integrity of the outflow barrel and permanent dam structure is of the highest importance.

b. This ensures that a small temporary riser is not installed to maintain peak flow rates by forcing a large head on top of the riser that could jeopardize the stability of the riser, barrel, and permanent dam.

2. Design the Primary Riser to have a Floating Skimmer attached to the bottom of the riser

(typically the post construction water quality low flow orifice) during the construction phase of the project to dewater in a time period ranging between 24 to 72 hours.

a. The Floating Skimmer provides withdraw from the water surface for the majority of storm events during the construction phase of the project.

3. Design the Primary Riser with orifices/weirs to provide peak flow rate control.

4. Design the Primary Riser to have a trash rack and anti-vortex device.

5. Provide a minimum of 1 row of Baffles during construction. Install at least 1 row of Baffles between the riser structure and all pipes or channels discharging to the Basin. Designers may use 0% dead space when using Baffles.

6. Provide calculations using Sedimot, SEDCAD, Pond Pack and other computer models or

Design Aids showing that the basin will meet a minimum 80% trapping efficiency during the construction phase of the project.

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7. Provide calculations showing that the basin is designed to meet pre-construction peak flow rates for the 2-year 10-year, and 25-year 24-hour storm events.

8. Design a stabilized Emergency Spillway that safely passes the 100-year 24-hr storm event with a minimum freeboard of 1.0 feet between the 100-year 24-hour water surface elevations to the top of the dam.

Post construction staged orifices, low flow orifices, or staged weirs are installed in the Primary

Riser structure prior to the construction phase.

6.2 OPTION B (PEAK FLOW CONTROL DURING CONSTRUCTION NOT REQUIRED)

Two spillway configurations are required for Permanent Multipurpose Basins that will not control peak flow rates during the construction phase of the project.

The first configuration is the Temporary Floating Skimmer & Baffle Sediment Basin Primary

Riser Spillway consisting of a solid riser with no staged discharges. Runoff only enters the

Primary Riser structure by overtopping and through the Floating Skimmer.

The second configuration is the Permanent Multipurpose Basin Riser spillway designed to reduce post-development peak flow rates to pre-development peak flow rates for the 2-year 10-year, and 25-year 24-hour storm events where applicable or designed for post-construction water quality control.

Post-construction staged orifices, low flow orifices, or staged weirs are securely covered or sealed during the construction phase.

Uncover post-construction staged orifices, low flow orifices, or staged weirs after the construction phase is complete.

Floating Skimmers and Baffles may be removed when the construction phase ends.

Clean the Temporary Floating Skimmer & Baffle Sediment Basin of deposited sediment and re-grade the Basin to meet the Permanent Basin contours if necessary when the construction phase ends.

Make any necessary modifications to the Emergency Spillway after the construction phase has ended.

A Temporary Floating Skimmer & Baffle Sediment Basin that is converted to a Permanent

Multipurpose post-construction basin will be retained and maintained after completion of the project.

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6.3 FOREBAYS

Forebays are required for all Multipurpose Basins. The function of the Forebay is to trap the majority of the coarse fractions of the suspended solids in the runoff before it enters the main dry detention area.

Provide a Forebay for all inlets to a Multipurpose Basins and place Forebays upstream of the main detention area. Each Forebay is sized according to the outlets contribution to the basin. A

Forebay is not required for an outlet that contributes less than 10% of the total drainage area or to the basin.

Design forebay side slopes to be 2H:1V or flatter.

The Forebay is separated from the larger Multipurpose Basin area by berms, barriers, or baffles that may be constructed of earth, stones, riprap, gabions, or geotextiles. The berm, barrier, or baffles act as a trap for coarse sediments and minimize their movement into the main detention basin.

Design the Forebay in a manner that it is accessible for easy cleanout because it will eventually fill in with coarse particles. Design the access to the Forebay with a maximum slope of 15-20 percent extending from the top of the embankment to the toe.

6.3.1 DRY PERMANENT MULTIPURPOSE BASIN FOREBAYS

Design the Forebay volume (or combined volume of Forebays):

Equal to a minimum of 10% of the overall post construction water quality treatment volume of the Multipurpose Basin, and/or

Equal to approximately 75 percent of the required sediment storage volume based on a minimum cleanout cycle of 5 years.

The forebay berm may incorporate drain pipe to drain the Forebay so it does not maintain a permanent pool.

6.3.2 WET PERMANENT MULTIPURPOSE BASIN FOREBAYS

Design the Forebay volume (or combined volume of Forebays):

Equal to a minimum of 10% of the overall post construction water quality treatment volume of the Multipurpose Basin, and/or

Equal to approximately 75 percent of the required sediment storage volume based on a minimum cleanout cycle of 5 years.

For Wet Permanent Multipurpose Basins, the forebay berm may incorporate drain pipe or be constructed of riprap to facilitate equalization of the pond over time. Design the top of the

May 2013 Fort Jackson Sediment Page 9 forebay barrier a maximum of 1-foot below the permanent pool elevation, and it may extend above the elevation of the permanent pool.

Design the forebay depth, as measured from the maximum water quality event surface level, between 4 and 6 feet. To minimize the re-suspension of settled particles, design the minimum permanent pool depth of water in the forebay 3-feet above the design sediment storage elevation.

Size the Forebay such that the average velocity of the flow in the Forebay for the 2-year 24-hour storm event does not exceed 1.0 foot per second (flow rate /average cross sectional area).

7.0 CONSTRUCTION

Construct the Floating Skimmer & Baffle Sediment Basin in accordance with these

Specifications, Standard Drawings, as indicated on the Plans, or as directed by the Engineer.

7.1 EQUIPMENT

Ensure that the equipment necessary for the proper installation of the Floating Skimmer & Baffle

Sediment Basin is on site, in acceptable working condition, and approved by the Engineer regarding both type and condition before the start of work under this section. Provide sufficient equipment to execute the work in accordance with the project schedule.

7.2 INSTALLATION REQUIREMENTS

Installation includes constructing the sediment basin, installing the Primary Riser Structure, installing the Riser Outlet Barrel, installing Baffles, furnishing, installation and cleanout of

Floating Skimmers, providing and placing Riprap pad on bottom of Basin underneath the

Floating Skimmer, providing and placing an Emergency Spillway and liner, disposing of excess materials, removing Baffles, Emergency Spillway liner and Floating Skimmer, backfilling basin area with suitable material and providing proper drainage when basin area is abandoned.

7.3 SITE WORK

Locate and construct the Floating Skimmer & Baffle Sediment Basin before performing other earthwork on-site. Clear and grub the entire area of the Basin and Emergency Spillway in accordance with the Plans. Turn the entire area to a depth of 6 inches with a disk harrow and compact it to 95.0% compaction. Fill all holes in the foundation area of the dam with suitable material and compact to 95.0% compaction.

7.4 TEMPORARY AND PERMANENT SEDIMENT CONTROL BASINS

Locate and construct the Floating Skimmer & Baffle Sediment Basin as shown in the Plans.

Construct the bottom of the Basin on a 0.5% slope. If the inflow into the Basin is from a pipe or from a ditch with a flow line higher than the bottom of the basin, place Riprap at the end of the pipe or ditch down to the bottom elevation of the Basin to prevent erosion.

Perform Temporary Stabilization by seeding and protect the temporary seeded area with a

Temporary ECB on all areas of the Basin, except for the bottom of the Basin.

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When grading operations are complete and the permanent grassing or stabilization is in place, restore the area occupied by the temporary Floating Skimmer & Baffle Sediment Basin as nearly as practicable to the original ground line and seed the area.

7.5 EARTH DAM EMBANKMENT

Construct the earth dam to the dimensions shown on the Plans. The maximum earth dam inside slopes is 3H:1V., and the maximum earth dam outside slopes is 3H:1V Typical earth dam height to top width dimensions are provided in the following table.

Dam Height (Ft) Minimum Top Width (Ft)

<10 8

11-14 9

15-19 10

For Permanent Multipurpose Basins construct a key and core on all earth dam embankment areas. Construct the key and core with clay or other impervious materials. Construct the dam core to the dimensions shown on the Plans and to an elevation level with the flowline of the

Emergency Spillway. Construct the core with a top width of 8 feet and 1:1 side slopes. Place fill adjacent to pipes or other structures in 4-inch layers and compact by hand or by manually directed tampers or plate vibrators. Place the fill over pipes to a minimum of 2 feet before using heavy equipment. Do not place fill around concrete structures until the concrete has cured sufficiently to support the load. As soon as final grades are reached, seed all areas.

7.6 AGGREGATE DIAPHRAGM OR ANTI SEEP COLLARS

Construct an aggregate diaphragm or anti seep collar parallel to the dam, around the outlet pipe immediately at the outlet side of the cutoff trench. Construct the aggregate diaphragm to a depth of 2 feet extending three times the pipe diameter vertically and horizontally, and a minimum of

18 inches beneath the pipe. Use FA-10 fine aggregate. Place a minimum of 2 feet of fill material over the diaphragm.

7.7 AGGREGATE DIAPHRAGM OR ANTI SEEP COLLARS

Construct an aggregate drain for the diaphragm, 1.5 times the diameter of the pipe or a minimum of 1 foot around the pipe, to the downstream edge of the dam. Use FA-10 fine aggregate for the aggregate drain. Install a Riprap pad over a fabric filter where the drain and the outlet pipe exit the fill. Extend the Riprap pad at least 2 feet outside the aggregate drain in all directions.

7.8 EMERGENCY SPILLWAY

Construct an Emergency Spillway on original ground at the grades and locations shown on the

Plans. Construct a spillway outfall channel to the main outfall channel as shown on the Plans.

Protect the Spillway by:

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1. Seeding the sides and bottom of the Emergency Spillway and spillway outfall channel and protecting the Spillway with an appropriate TRM as directed by the Engineer unless otherwise specified on the Plans.

2. Lining the sides and bottom of the Emergency Spillway and spillway outfall channel with a non-woven geotextile fabric and protecting the Spillway with Class B Riprap, as directed by the Engineer, or as shown on the Plans.

7.9 PRIMARY RISER SPILLWAY AND OUTLET BARREL

Temporary Floating Skimmer & Baffle Sediment Basin Primary Riser Spillways consists of a solid circular concrete monolithic base or extended base riser with no staged orifices.

Multipurpose Floating Skimmer & Baffle Sediment Basin Primary Riser Spillways consist of a reinforced concrete riser with staged orifices/weirs.

For Temporary Floating Skimmer & Baffle Sediment Basin, install the top of the Primary Riser at a minimum elevation 4.0 feet above the Basin bottom.

Install the Primary Riser Spillway after final grading and excavating the Basin footprint is complete. Use the following instructions when installing the Primary Riser Spillway:

1. Remove all loose soil and debris in the area where the riser is installed.

2. Excavate, prepare, and compact the location of the riser with dimensions two (2) feet greater than the riser bottom diameter.

3. Place the concrete Primary Riser and level the structure with the appropriate equipment.

4. Join all Outlet Barrel Pipe sections to the Riser so that the connections are water tight.

5. Fill the riser bottom to the flow line of the Outlet Barrel Pipe as required.

6. Join all Outlet Barrel Pipe so that the connections are water tight.

For Temporary Floating Skimmer & Baffle Sediment Basin, use either polyethylene Type C or corrugated steel pipe or reinforced concrete pipe for the Outlet Barrel, and use reinforced concrete pipe or corrugated metal pipe for the Primary Riser. Use the pipe sizes shown on the

Plans.

For Multipurpose Basins, construct a Primary Riser consisting of reinforced concrete pipe. Place a stub out de-watering orifice at the same flow line as the Outlet Barrel as shown on the Plans.

Use either reinforced concrete or aluminum alloy pipe for the Outlet Barrel. Join all pipe sections so that the connections are watertight.

Place a trash rack and anti-vortex device over the top of the Primary Riser as shown on the Plans.

Use the diameter indicated on the Plans for the Primary Riser and the Outlet Barrel.

Place the Outlet Barrel on a minimum 0.5% slope.

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Provide outlet protection to prevent erosion and scouring using Riprap, TRM, or similar erosion prevention at the barrel outlet of the Basin. Ensure outlet velocities do not exceed the capability of the BMP selected.

Line the outflow channel with Class B Riprap or install a stilling basin as indicated on the Plans.

Use a non-woven geotextile under the Riprap.

7.10 FLOATING SKIMMER

Install an appropriate Floating Skimmer attached to the bottom of the Primary Riser structure.

Excavate a shallow pit under the Floating Skimmer to account for sediment that accumulates on the Basin bottom around the Floating Skimmer. The pit allows the Floating Skimmer to completely drain the basin. At a minimum, the pit has dimensions of 4feet x 4feet with a minimum depth of 2 feet. Fill the Skimmer Pit with Class A or Class B Riprap to the top elevation of the Skimmer Pit. Ensure the top elevation of the Skimmer Pit is lower than the invert of the outlet barrel from the riser.

7.11 BAFFLES

Install 1 row of Baffles a minimum of 4-feet in height with a spacing of 1/3 the basin length.

Ensure that at least 1 row of Baffles is placed between the Primary Riser structure and all pipes or channels discharging to the Basin.

Baffles may consist of Porous Baffles, or Riprap Baffles.

Install Riprap Baffles a minimum of 4-feet in height consisting of Class A or B Riprap. Do not place washed stone on the face of the Riprap Baffles.

7.12 SEDIMENT CLEANOUT STAKE

Install a metal sediment clean out stake that is 4-feet above the Basin bottom in the first Baffle cell upstream of the first Baffle. Cleanout the Surface Outlet and Baffle Sediment Basin when the sediment level reaches the 2-foot mark on the sediment cleanout stake (50% of the sediment storage volume).

8.0 INSPECTION AND MAINTENANCE

The key to a functional Floating Skimmer & Baffle Sediment Basin is continual monitoring, regular maintenance and regular sediment removal. Attention to sediment accumulations within the Basin is extremely important. Continually monitor sediment deposition in the Basin.

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Inspect Floating Skimmer & Baffle Sediment Basins a minimum of once per week and make necessary repairs immediately, inspections are also recommended within 24-hours after each rainfall event that produces ½-inches or more of precipitation until final stabilization is achieved.

Inspect all Floating Skimmer & Baffle Sediment Basin components including but not limited to:

Inlet/outlet pipes – Inspect pipes for sediment and debris blockage, maintenance is required when the pipe is 1/3 blocked or damaged to a point to restrict flow.

Inlet /outlet protection – Inspect inlet/outlet protection and repair or replace when protection is damaged, Riprap is displaced, or covered by sediment.

Floating Skimmer - Inspect the Floating Skimmer after each rain event to ensure that it is not clogged with sediment. Remove sediment that accumulates on the Riprap pad underneath the

Floating Skimmer.

Inspect Floating Skimmer & Baffle Sediment Basin after each significant rainfall.

Inspect the Emergency Spillway for erosion and damage.

Clean trapped sediment from Surface Outlet and Baffle Sediment Basin when sediment accumulations reach the 2-foot mark on the sediment clean out stake.

Remove trapped sediment from the site, or stabilized on site.

Repair, seed, and replace ECBs on Basin side slope areas that have eroded or have become damaged by equipment from silt cleanout.

Inspect Baffles after each…