Attachment__12_-_Passenger_Terminal_OS-SWPPP_dated_2_October_2013.pdf

RENOVATE (ADD/REPAIR) PASSENGER TERMINAL, BLDG. 164 DKFX 11-1122 A/B

Final Submittal DESIGN NARRATIVE Part II - SWPPP

ADC Project No. 12125 Page 1 10/02/2013

Onsite Stormwater Pollution Prevention Plan (OS- SWPPP) For Construction Activities:

Project/Site Name:

Renovate (Add/Repair) Passenger Terminal, Bldg. 164

Project Address/Location:

Joint Base Charleston - Air Base

North Charleston, SC 29404

Primary Permittee:

Joint Base Charleston - Air Base

Permittee/Owner Contact:

628 CES/CEPMF

210 W. Stewart Avenue Joint Base Charleston, SC 29404

Tom Bone Ph: (843) 963-1499 / Fax: (843) 963-4993 thomas.bone@us.af.mil

SWPPP Preparer:

ADC Engineering, Inc.

Larry Barthelemy, PE

1226 Yeamans Hall Road Hanahan, South Carolina 29410

Ph: (843) 566-0161 / Fax: (843) 566-0162 LarryB@adcengineering.com

Day-to-Day Operator:

(Leave Blank if not known.)

C-SWPPP Preparation Date:

revised - October 2, 2013

Attachment #12 Add/Repair Passenger Terminal, Bldg 164 FA4418-16-R-0002

ADC Project No. 12125 Page 3 10/02/2013

Table of Contents

SECTION 1 – PROJECT OVERVIEW

1.1. Narrative

1.2. Stormwater Management and Sediment Control

1.3. Sequence of Construction

1.4. Non-Numeric Effluent Limits

1.5. Buffer Zone Management

SECTION 2 – SITE FEATURES AND SENSITIVE AREAS

2.1. Sources of Pollution

2.2. Surface Waters

2.3. Impairments and TMDLs

2.4. Critical Areas (CZC only)

SECTION 3 – COMPLIANCE REQUIREMENTS

3.1. SWPPP Availability

3.2. Pre-Construction Conferences

3.3. Inspection Requirements

3.4. Maintenance Requirements

3.5. Record Keeping

3.6. Final Stabilization

Appendix A – Stormwater Applications & Permits Appendix B – Maps (Vicinity, Quadrangle, FIRM, Aerial, Soils, Wetlands) Appendix C – Contractor Certifications Appendix D – Inspection Log and Reports Appendix E – Rainfall Log and Reports Appendix F – Additional Site Logs and Records Appendix G – Construction General Permit SCR100000

*C-SWPPP is acronym for Comprehensive Storm Water Pollution Prevention Plan **OS-SWPPP is acronym for On-Site Storm Water Pollution Prevention Plan

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SECTION 1 – PROJECT OVERVIEW

1.1. Narrative

A. Construction Activities and BMP Summary

The construction site will include minor clearing and grubbing of existing grass and landscape areas, pavement repair along the flightline, and a new drop-off loop. A variety of stormwater pollution controls are recommended for this project. Some controls are intended to function temporarily and will be used as needed for pollutant control during the construction period. These include temporary sediment barriers and check dams. Permanent stabilization will be accomplished in all disturbed areas by covering the soil with pavement, vegetation, or other forms of soil stabilization.

The construction activities at this site will be implemented in two (2) distinct Erosion Prevention and Sediment Control Phases. The first phase includes the initial installation of perimeter controls, sediment control BMPs, and construction entrances. The final phase, Phase 2, includes the bulk of the construction activities and final stabilization of the site.

B. Pre-Development Conditions

This parcel consists of the passenger terminal Building 164, a sheltered smoking area, a small utility shed and asphalt surrounding three sides of Building 164.

The existing parcel is comprised of two drainage basins referred to herein as ‘Basin A’ and ‘Basin B’.

‘Basin A’ is 3.29 acres that sheet flows into two separate portions of the existing drainage system that conveys stormwater to the existing concrete channel located near the southwest corner of the passenger terminal building.

‘Basin B’ contains another existing drainage system that consists of an open channel system and culverts located on the other side of Bates Street that bounds the west side of the project site. ‘Basin B’ collects runoff from Bates Street, totaling 0.15 acres. The existing channel guides the stormwater to a collector ditch that also receives stormwater from ‘Basin A’ and conveys the stormwater to the Ashley River.

Refer to the Site Plans and Engineering Report for additional information.

C. Post-Development Conditions

The proposed site includes modifications and improvements to the existing system.

The proposed site is comprised of two drainage basins referred to herein as ‘Basin A’ and ‘Basin B’.

‘Basin A’ is made up of pervious and impervious areas totaling 3.29 acres. Stormwater runoff from ‘Basin A’ is collected by two separate portions of the existing storm drainage system. The portion of the existing storm drainage system located west of the passenger terminal building includes new drainage structures and piping. The other portion of the existing storm drainage system located on the east and south side of the building collecting sheet flow in ‘Basin A’ and offsite run on has been modified. A new trench drain and catch basin will now convey the stormwater to the existing concrete swale that leads to the concrete channel where all stormwater from ‘Basin A’ and offsite run on is collected.

‘Basin B’ consists of pervious and impervious areas totaling 0.15 acres. Runoff from ‘Basin B’ sheet flows into the existing channel under a new sidewalk and continues to a collector ditch that conveys stormwater from both ‘Basin A’ and ‘Basin B’ to the Ashley River.

Refer to the Site Plans and Engineering Report for additional information.

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Water Quality

Given the nature of the project, a request for a waiver of stormwater management for qualitative control of the State Stormwater Management and Sediment Reduction Act and NPDES Construction General Permit will be submitted.

In an effort to improve water quality, this project will include 12 inch sumps in the drainage structures which will allow sediment and debris to collect.

Water Quantity

Additionally, a request for a waiver of stormwater management for quantitative control of the State Stormwater Management and Sediment Reduction Act and NPDES Construction General Permit will be submitted.

In conjunction with other projects on base, the subject project proposes to add no appreciable increase in impervious area to Joint Base Charleston as a whole. Therefore, this project will result in no significant adverse impact on the receiving natural waterway or downstream properties.

Basin Data Storm Data Pre-Development

Conditions Post-Development

Conditions

Basin A

Impervious Area 2.10 2.09 Pervious Area 1.19 1.20 Total Area 3.29 3.29 Composite C 0.68 0.68 Cumulative CN 92 92 10-yr runoff (cfs) 16.15 16.10

Basin B

Impervious Area 0.09 0.09 Pervious Area 0.06 0.06 Total Area 0.15 0.15 Composite C 0.64 0.64 Cumulative CN 91 91 10-yr runoff (cfs) 0.69 0.70

D. Flooding Issues

The site is not located in a flood zone from scaling the FEMA Map (Community numbers 455413 & 450042, Panel 0295, Suffix ‘J’, dated November 17, 2004, Zone X). The site is not subject to flooding.

Refer to Attachment A – Site Maps, of the Design Narrative, for FEMA map.

1.2. Stormwater Management and Sediment Control

A. Erosion Prevention BMPs

As the existing site is developed as shown on the construction site plans, erosion prevention BMPs shall be placed throughout the construction site to aid in the prevention of sediment-laden stormwater runoff. These BMPs shall be focused in areas with high potential of erosion, areas preceding infiltration practices, and shall be applied to all steep slopes (equal to or greater than 3H:1V).

The purpose of soil stabilization is to prevent soil from eroding and leaving the site. In the natural condition, soil is stabilized by native vegetation. The primary technique to be used at this project for stabilizing site soils will be to provide a protective cover of grass or pavement.

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1) Temporary Seeding or Stabilization – All denuded areas that will be inactive for 14 days or more, must be stabilized temporarily with the use of fast-germinating annual grass/grain varieties appropriate for site soil and climate conditions, straw/hay mulch, wood cellulose fibers, tackifiers, netting and/or blankets. Stockpiles and diversion ditches/berms must be stabilized to prevent erosion and dust issues. Stormwater conveyance BMPs (diversion ditches, dikes, channels, etc.)

shall be stabilized within 7 days of construction.

2) Permanent Seeding, Sod or Mulching – All areas at final grade must be seeded, mulched or covered with sod within 14 days after completion of work in that area. Seed immediately after final grade is achieved and soils are prepared to take advantage of soil moisture and seed germination.

At the completion of ground-disturbing activities the entire site must have permanent vegetative cover, meeting vegetative density requirements, or mulch per landscape plan, in all areas not covered by hardscape (pavement, buildings, etc.).

3) Energy Dissipaters – Energy Dissipaters reduce runoff velocities from concentrated conveyance systems (pipes and swales), enhance the potential for infiltration and protect the soil from the erosive force of concentrated flows. Energy dissipaters include riprap aprons, level spreaders and soil reinforcement (such as erosion control blankets and turf reinforcement mats).

B. Sediment Control BMPs

Sediment Control BMPs are designed to remove some of the sediment accumulated within stormwater runoff, to the best extent practicable. These BMPs help prevent sediment impacts to adjacent properties and water bodies from stormwater discharges originating from construction sites.

1) Silt Fence – Silt fence is a synthetic permeable woven or non-woven geotextile fabric incorporating metal support stakes at intervals sufficient to support the fence (5-feet maximum distance between posts), water, and sediment retained by the fence. The fence is designed to retain sediment-laden stormwater and allow settlement of suspended soils before the stormwater flows through the fabric and discharges from the site. Silt fence shall be located on the contour to capture overland, low-velocity sheet flows and is typically installed with a wire fence backing for additional support.

Install silt fence at a fairly level grade along the contour with the ends curved uphill to provide sufficient upstream storage volume for the anticipated runoff. Drainage areas shall not exceed ½ acre per 100 feet of wire-reinforced silt fence for slopes less than 2 percent.

2) Check Dams – Defined channels subject to concentrated flows in larger quantities and higher velocities may be protected with rock or other manufactured device that can be used as a check dam. The dams impound sediment-laden water and allow for settlement of suspended soil before the stormwater flows over and through the device. Dams shall be placed along the water course at linear intervals in which the elevation of the bottom of the upper most check dam is at the same elevation as the top of the check dam immediately below it. This will allow the most ponding capacity and will not increase the velocity of the water flowing along the channel. Check dams are composed of crushed stone or rip rap or of other manufactured devices.

3) Storm Sewer Inlet Protection – Drainage inlets are protected from the intrusion of sediment through a variety of measures as shown on the details included in the Construction drawings. The primary mechanism is to place controls in the path of flow sufficient to slow the sediment-laden water to allow settlement of suspended soils before discharging into the storm sewer. It is possible that as construction progresses from storm sewer installation through to paving that the inlet protection devices will change.

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C. Structural Control BMPs and Floodplain Placement

Not applicable.

D. Construction Entrances and Dust Control

All access areas into and out of the limits of disturbance, as shown on the construction site plans, are required to be equipped with a construction entrance. The use of this BMP will limit the amount of sediment being transported by construction vehicles onto existing roadways or other impervious areas.

Any tracked sediment, along with any attached pollutants, deposited on impervious areas could be washed downstream during the next rain event. Each construction entrance must be installed as shown in the details section of the construction site plans.

If a new entrance or exit is required, that is not shown on the plans, install the construction entrance as noted by the construction entrance detail, mark the location on the plans and make a record of this minor modification in the SWPPP’s modification log, which is located within one of the appendices of the On-site SWPPP.

Each stabilized construction entrance should be used in conjunction with street sweeping measures if it becomes apparent that sediment is still being tracked onto adjacent impervious areas, even with the use of the construction entrance.

During extremely dry conditions, drought, and/or excessive winds, the construction site should be treated for dust control to prevent the suspension of fine sediment particles into the air, being carried offsite, and deposited on adjacent properties or surface waters. This practice may not be directly called out for on the construction site plans. A water tanker used to spray the soil down may be an effective way to prevent excessive dust at a construction site.

E. Water Quality BMPs During Construction

Not applicable.

F. Post-Construction Water Quality

Grass Lined Ditches and Swales – Grass lined swales capture, treat and release storm water from a particular drainage area. Grass lined swales filter out contaminates to improve water quality. Grass swales provide very little stormwater storage and must be used in conjunction with other BMPs to meet water quantity requirements.

Vegetated Filter Strips - Vegetated filter strips are zones of vegetation where pollutant-laden runoff is introduced as sheet flow. Vegetated filter strips may take the form of grass filters, grass filter strips, buffer strips, vegetated buffer zones, riparian vegetated buffer strips, and constructed filter strips.

Vegetated filter strips are used to remove pollutants from overland sheet flow but are not effective in removing sediment from concentrated flows. Vegetated filter strip effectiveness fluctuates considerably depending on vegetation type, vegetation height and density, season of the year, eroded particle characteristics, size of drainage area, and site topography.

G. Other Stormwater Management Procedures

Construction Debris Management: Based on the nature, conditions, and/or procedures associated with this construction site, the following items must be followed and adopted by all those conducting land disturbing activities at this site:

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Stockpile Management - Stockpiles of soil shall be protected during construction. Silt fence shall be installed around the downstream side of the stockpile to prevent sedimentation. Additionally, stockpiles of soil shall be temporarily stabilized to control erosion. Stockpiles of construction debris, including soil, shall have all runoff directed to a sediment basin or trap.

Non-Stormwater Discharges / Dewatering – Non-stormwater components of site discharges must be clean water. Water used for construction which discharges from the site must originate from a public water supply or private well approved by the State Health Department. Water used for construction that does not originate from an approved public supply must not discharge from the site. It can be retained in the ponds until it infiltrates and evaporates. Other non-stormwater discharges would include ground water. Only uncontaminated ground water can be discharged from the site, as allowed by and in accordance with applicable local ground water dewatering permits/regulations. When non-stormwater is discharged from the site, it must be done in a manner such that it does not cause erosion of the soil during discharge.

Process water such as power washing and concrete cutting must be collected for treatment and disposal. It is not to be flushed into the site storm drain system. A groundwater dewatering permit is not required.

Verify discharges from dewatering activities are allowed non-stormwater discharges under the General Permit. Allowable non-stormwater discharges include:

1. Discharges from fire-fighting activities;

2. Fire hydrant flushings;

3. Waters used to wash vehicles where detergents are not used;

4. Water used to control dust in accordance with Section 3.2.2 (Stormwater Management and Sediment Control);

5. Potable water including uncontaminated water line flushings;

6. Routine external building wash down that does not use detergents;

7. Pavement wash waters where spills or leaks of toxic or hazardous materials have not occurred (unless all spilled material has been removed) and where detergents are not used;

8. Uncontaminated air conditioning or compressor condensate;

9. Uncontaminated ground water or spring water;

10. Foundation or footing drains where flows are not contaminated with process materials such as solvents;

11. Uncontaminated excavation dewatering;

12. Landscape irrigation; and

Obtain a dewatering permit according to state and local regulations, if discharges from dewatering activities are not allowed under the General Permit. Discharges from dewatering operations must be directed through an appropriate pollution prevention/treatment measure, such as a pump discharge filter bag, sediment trap or sediment basin prior to being discharged from the site or into a water body of the State. Under no circumstances are discharges from dewatering operations to be discharged directly into streams, rivers, lakes or other areas beyond the permitted project area. Likewise, discharges into storm sewer systems that do not drain to a suitable on-site treatment facility, such as a

ADC Project No. 12125 Page 9 10/02/2013 basin, are also prohibited. Discharges from dewatering operations must also be conducted in a manner sufficient to prevent erosion from the discharge runoff.

Use best management practices when dewatering. Place intake hose on a flotation or similar device and do not pump directly from the bottom of the basin, trench, etc. Always pump through a sediment control BMP and dewater within the permitted limits of disturbance to ensure discharge criteria are achieved. Do not discharge on a slope greater than three percent or within 20’ of a surface water body.

Dewatering should not occur during or immediately after precipitation events, but exceptions will be evaluated on case by case basis.

Solid Waste Disposal - No solid materials, including building materials, are allowed to be discharged from the site with stormwater. All solid waste, including disposable materials incidental to the major construction activities, must be collected and placed in containers. The containers will be emptied when 95% full, or as necessary, by a certified trash disposal service and hauled away from the site.

Covers for the containers will be provided as necessary to meet state and local requirements.

Construct covers as practicable, or required, to prevent stormwater contact and pollutant discharges from solid waste receptacles. The location of solid waste receptacles shall be shown on the Drawings.

Substances that have the potential for polluting surface and/or groundwater must be controlled by whatever means necessary in order to ensure that they do not discharge from the site. As an example, special care must be exercised during equipment fueling and servicing operations. If a spill occurs, it must be contained and disposed of so that it will not flow from the site or enter groundwater, even if this requires removal, treatment, and disposal of soil. In this regard, potentially polluting substances should be handled in a manner consistent with the impact they represent.

Sanitary Facilities - All personnel involved with construction activities must comply with state and local sanitary system regulations. Temporary sanitary facilities will be provided at the site throughout the construction phase. They must be utilized by all construction personnel and will be serviced by a commercial operator. The location of sanitary facilities shall be shown on the Drawings. Portable toilets must be securely anchored and are not allowed within 30’ of inlets or permitted limit of disturbance or within 50’ of a water of the State.

Concrete Waste from Concrete Ready-Mix Trucks - Discharge of excess or waste concrete and/or wash water from concrete trucks will be allowed on the construction site, but only in approved aboveground portable concrete washout containers (preferred) or in specifically designated lined and diked areas prepared to prevent contact between the concrete and/or wash water and stormwater that will be discharged from the site. The General Contractor shall eliminate or minimize the number of seams in the liner.

Alternatively, waste concrete can be placed into forms to make rip rap or other useful concrete products. The cured residue from the concrete washout diked areas shall be disposed in accordance with applicable state and federal regulations. This jobsite superintendent is responsible for assuring that these procedures are followed. The location of concrete washout areas shall be shown on the Drawings. Follow all applicable environmental regulations for concrete wash out pits.

SCDHEC requires all concrete waste areas to be a minimum of 50 feet away from any inlet or other conveyance system.

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Masons’ Area - Contractor shall identify masons’ area on the site and indicate location on the Drawings. To the extent practical, all masonry tools, material, including sand and sacked cement or mortar materials, and equipment shall be located within the area identified. Runoff control, such as berms or diversion ditches, silt fence, straw wattles, or other means of containment shall be provided to prevent the migration of stormwater pollutants in runoff from the masons’ area. Receptacles for debris and trash disposal shall also be provided.

Fuel Tanks - Temporary on-site fuel tanks for construction vehicles shall meet all state and federal regulations. Tanks shall have approved spill containment with the capacity required by the applicable regulations. From NFPA 30: All tanks shall be provided with secondary containment (i.e. containment external to and separate from primary containment). Secondary containment shall be constructed of materials of sufficient thickness, density, and composition so as not to be structurally weakened as a result of contact with the fuel stored and capable of containing discharged fuel for a period of time equal to or longer than the maximum anticipated time sufficient to allow recovery of discharged fuel. It shall be capable of containing 110% of the volume of the primary tank if a single tank is used, or in the case of multiple tanks, 150% of the largest tank or 10% of the aggregate, whichever is larger.

The tanks shall be in sound condition free of rust or other damage which might compromise containment. Fuel storage areas will meet all EPA, OSHA and other regulatory requirements for signage, fire extinguisher, etc. Hoses, valves, fittings, caps, filler nozzles, and associated hardware shall be maintained in proper working condition at all times. The location of fuel tanks shall be shown on the Drawings and shall be located to minimize exposure to weather and surface water drainage features.

A Spill Prevention, Control and Countermeasure (SPCC) Plan must be developed if aboveground oil storage capacity at the construction site exceeds 1,320-gallons or as specified by SCDHEC.

Containers with a storage capacity of 55-gallons or less are not included when calculating site storage capacity. The General Contractor shall work with the CEC to develop and implement a SPCC Plan in accordance with the Oil Pollution Prevention regulation at Title 40 of the Code of Federal Regulations, Part 112, (40 CFR 112).

Hazardous Material Management and Spill Reporting Plan - Any hazardous or potentially hazardous material that is brought onto the construction site will be handled properly in order to reduce the potential for stormwater pollution. All materials used on this construction site will be properly stored, handled, dispensed and disposed of following all applicable label directions. Flammable and combustible liquids will be stored and handled according to 29 CFR 1926.152. Only approved containers and portable tanks shall be used for storage and handling of flammable and combustible liquids.

Material Safety Data Sheets (MSDS) information will be kept on site for any and all applicable materials.

In the event of an accidental spill, immediate action will be undertaken by the General Contractor to contain and remove the spilled material. All hazardous materials, including contaminated soil and liquid concrete waste, will be disposed of by the Contractor in the manner specified by federal, state and local regulations and by the manufacturer of such products. As soon as possible, the spill will be reported to the appropriate agencies. As required under the provisions of the Clean Water Act, any spill or discharge entering waters of the United States will be properly reported. The General Contractor will prepare a written record of any spill and associated clean-up activities of petroleum products or hazardous materials in excess of 1 gallon or reportable quantities, whichever is less. The

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General Contractor will provide notice to Owner, via the SWCT Hotline, immediately upon identification of a reportable spill. A spill report form is located in Appendix H.

Any spills of petroleum products or hazardous materials in excess of Reportable Quantities as defined by EPA or the state or local agency regulations, shall be immediately reported to the EPA National Response Center (1-800-424-8802) and SCDHEC (1-888-481-0125) .

The State reportable quantity for petroleum products is: 25 gallons.

The reportable quantity for hazardous materials can be found in 40 CFR 302 and South Carolina Code of Regulations 61-79 (www.scstatehouse.gov/coderegs/C061d.htm).

In order to minimize the potential for a spill of petroleum product or hazardous materials to come in contact with stormwater, the following steps will be implemented:

a) All materials with hazardous properties (such as pesticides, petroleum products, fertilizers, detergents, construction chemicals, acids, paints, paint solvents, additives for soil stabilization, concrete, curing compounds and additives, etc.) will be stored in a secure location, under cover and in appropriate, tightly sealed containers when not in use.

b) The minimum practical quantity of all such materials will be kept on the job site and scheduled for delivery as close to time of use as practical.

c) A spill control and containment kit (containing for example, absorbent material such as kitty litter or sawdust, acid neutralizing agent, brooms, dust pans, mops, rags, gloves, goggles, plastic and metal trash containers, etc.) will be provided on the construction site and location(s) shown on Drawings.

d) All of the product in a container will be used before the container is disposed of. All such containers will be triple rinsed, with water prior to disposal. The rinse water used in these containers will be disposed of in a manner in compliance with state and federal regulations and will not be allowed to mix with stormwater discharges.

e) All products will be stored in and used from the original container with the original product label.

f) All products will be used in strict compliance with instructions on the product label.

g) The disposal of excess or used products will be in strict compliance with instructions on the products label.

1.3. Sequence of Construction

The construction sequence for this project has been provided on the construction site plans. Each item/step of that construction sequence has been listed is the sequence that they should be implemented.

For additional information or questions on the sequencing please contact the SWPPP Preparer or the Permittee referenced on the cover of this SWPPP.

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1.4. Non-Numeric Effluent Limits

A. Stormwater Volume and Velocity Control

During the implementation of construction activities, all parties performing work at this construction site whose work may affect the implementation of the SWPPP must be informed of and directed on how to comply with this Non-Numeric Effluent Limit, which requires the management of stormwater runoff within the construction site and at each outfall. The purpose of this requirement is to control the stormwater volume and velocity at these locations to minimize erosion.

Specifically, each responsible party should be made aware of the practices that have been or should be implemented at the construction site to accomplish these particular stormwater management practices. Below is a list of practices that may be utilized within the disturbed area and at each outfall at construction sites to control stormwater volume and velocity:

1. Volume Control

a. Limiting the amount of disturbed area and exposed soils

b. Staging and/or Phasing of the Construction Sequence;

c. Sediment Basins and Sediment Traps

d. Diverting off-site flow around the construction site;

e. Controlling the Drainage Patterns within the Construction Site;

f. Temporary Stabilization of Disturbed Areas.

2. Velocity Control

a. Surface Roughening and/or other Slope Stabilization Practices;

b. Level Spreaders, Riprap Plunge Pools and/or other Velocity Dissipation BMPS located at the Construction Site's and Sediment Basin Outfalls.

c. Use of Rock Checks, Sediment Tubes, Etc. in Temporary Diversions Swales and Ditches.

d. Use of Erosion Control Blankets, Turf Reinforcement Mats, and other Non-Vegetative BMPs that can be used to Quickly Stabilize Disturbed Areas.

The SWPPP Preparer/Engineer should approve any modifications (Additional BMPs or Changes to Existing BMPs) to address the management of stormwater volume and velocity prior to implementation.

All approved SWPPPs that were issued coverage under the CGP should include ample BMPs and other control measures to address this specific Non-Numeric Effluent Limit.

B. Soil Exposure, Compaction and Preservation

Throughout construction activities, the amount of soil exposed during construction should be kept to a minimum. This may be accomplished by minimizing the amount the disturbed area within the permitted Limits of Disturbance (shown on the approved construction site plans) to only that which is necessary to complete the proposed work. For areas that have already been disturbed and where construction activities will not begin for a period of 14 days or more, temporary stabilization techniques must be implemented.

Prior to implementation of any major grading activities, topsoil is to be preserved by placing it in areas designated for stockpiling until final grades are reached. Each stockpile must be equipped with proper sediment and erosion controls to preserve the topsoil and protect adjacent areas from impacts.

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Once final grades have been reached, the preserved topsoil should be utilized to apply to areas identified for stabilization. Topsoil contains nutrients and organisms that aid in the growth of vegetation.

The Compaction of Soil should also be minimized to the degree practicable during grading activities.

This is especially important during the replacement of topsoil to aid in a quick establishment of vegetative cover. Compaction of soil may also reduce rainfall's ability to infiltrate into the soil, increasing the amount of stormwater runoff.

C. Soil Stabilization

Throughout construction activities, soil stabilization techniques are to be initiated as soon as practicable whenever any clearing, grading, excavating, or other land-disturbing activities have permanently or temporarily ceased on any portion of the construction site and will not resume for a period exceeding 14 calendar days. For areas where initiating stabilization measures is infeasible, (e.g., where snow cover, frozen ground, or drought conditions preclude stabilization), initiate vegetative or non-vegetative stabilization measures as soon as practicable.

D. Steep Slopes

All disturbed steep slopes, and steep slopes to be created through grading activities, must be managed in a fashion that limits the potential of erosion along the slopes. All parties whose work is/was responsible for the creation/disturbance of steep slopes must comply with the following items:

Minimize the Disturbance of all steep slopes, when possible.

Divert Concentrated or Channelized Flows of stormwater away from and around steep slope disturbances.

Use Specialized BMP Controls including temporary and permanent seeding with soil binders, erosion control blankets, surface roughening, grass-lined channels, and check dams to minimize erosion.

Initiate Stabilization Measures as soon as practicable on any disturbed steep slope areas where construction activities have permanently or temporarily ceased, and will not resume for a period exceeding 7 calendar days.

A Vegetative and/or Non-Vegetative Cover must be established within 3 working days from the time that stabilization measures were initiated.

Stabilization of steep slopes should be a priority for those performing work at the construction site. At the very least, runoff control BMPs should be implemented to transport stormwater runoff from the top of the slope to the toe of the slope. An example of this is to install diversion swales along the top of slope and direct the runoff towards pipe slopes drains to transports the runoff to the toe of the slope. All pipe slope drain outlets are to be equipped proper outlet protection.

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E. Sediment Discharge Minimization

Permittees, Contractors, and all other parties responsible for conducting land-disturbing activities are required to install and maintain all erosion and sediment BMPs that are identified on the approved construction site plans. These BMPs have been designed and approved to address such factors as the amount, frequency, intensity and duration of precipitation, the nature of resulting stormwater runoff, and soil characteristics, including the range of soils particle sizes expected to be present on the construction site. Proper installation, inspection, and maintenance will allow these BMPs to operate at maximum efficiencies in order to minimize sediment discharges to the maximum extent practical.

F. Pollutant Discharge Minimization

Permittees, Contractors, and all other parties responsible for conducting land-disturbing activities are required to install, implement, and maintain effective pollution prevention measures to minimize the discharge of pollutants. At a minimum, the following items must be implemented:

Minimize the discharge of pollutants from dewatering trenches and excavations by managing runoff with the appropriate controls. Otherwise these discharges are prohibited;

Minimize the discharge of pollutants from equipment and vehicle washing, wheel wash water, and other wash waters. Wash waters must be treated in a sediment basin or alternative control that provides equivalent or better treatment prior to discharge;

Minimize the exposure of building materials, building products, construction wastes, trash, landscape materials, fertilizers, pesticides, herbicides, detergents, sanitary waste and other materials present on the site to precipitation and to stormwater; and

Minimize the discharge of pollutants from spills and leaks and implement chemical spill and leak prevention and response procedures.

G. Prohibited Discharges

Permittees, Contractors, and all other responsible parties for conducting land-disturbing activities are prohibited to discharges, from the construction site, the following items:

Wastewater from washout of concrete, unless managed by an appropriate control;

Wastewater from washout and cleanout of stucco, paint, form release oils, curing compounds and other construction materials;

Fuels, oils, or other pollutants used in vehicle and equipment operation and maintenance; and

Soaps or solvents used in vehicle and equipment washing.

1.5. Buffer Zone Management

Not applicable.

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SECTION 2 – SITE FEATURES AND SENSITIVE AREAS

2.1. Sources of Pollution

Throughout construction activities, each permittee, contractor, and person responsible for conducting work will need to ensure that sources of pollution are managed to prevent their discharge from the construction site. Expected pollution sources during construction have been identified in Table 2.1-A, but due to the nature of construction activities, it is often tough to predict all pollution sources that may appear throughout the life of a construction project. For that reason, the following table has also been provided to help all those performing work at this construction site identify possible sources of pollution Stormwater runoff subjected to the identified pollution sources must be treated by the appropriate BMPs as directed by this SWPPP.

In the event that any additional sources of pollution are identified during construction, the person(s) with day-to-day operational control at the site is to add the new source(s) to Table 2.1-A and consult with the SWPPP Preparer to properly address this source and to prevent the discharge of it's pollutant through stormwater runoff.

Table 2.1-A: Potential Sources of Pollution

Source Material or Chemical

Location* Appropriate Control Measures

Loose soil exposed/disturbed during clearing, grubbing and grading activities

Sediment All areas within the Limits of Disturbance

As directed by the construction Plans.

This includes Silt Fence, sediment tubes, sediment basins, and sediment traps.

Areas where construction equipment are cleaned, a.k.a.

concrete washout

Heavy Metals & pH

Located adjacent to each construction entrance

Concrete Washout Basin.

Water encountered during trenching

Nutrients & Sediment

In and around any trenching activities.

Direct water into impoundments such as basins or traps to allow for the sedimentation of the listed pollutants.

Paving Operations Sediment &

Trash

All areas to be paved.

Inlet protection.

Material Delivery and Storage Areas

Nutrients, pH, Sediment, Heavy Metals, oils & grease

All areas used as storage areas

Silt fence and/or sediment dikes

Equipment fueling and maintenance areas

Metals, hydrocarbons, oils and greases

Areas surrounding fuel tanks

Provide secondary containments, locate in upland areas. Repair leaking and broken hoses.

Paints

Metal oxides, stoddard solvent, talc, calcium-carbonate, arsenic

Throughout site, primarily in areas of building construction

Washwater should be contained and is prohibited from being discharged

*Area where material/chemical is used on site

ADC Project No. 12125 Page 16 10/02/2013

2.2. Surface Waters

Stormwater runoff from the proposed construction site discharges to a tributary of Ashley River which is located southwest of the construction site. From the unknown tributary the storm runoff from this site will enter the Ashley River. The Ashley River discharges into the Charleston Harbor/Atlantic Ocean.

2.3. Impairments and TMDLs

The unknown tributary of the Ashley River has not been classified as "impaired".

A. Impairments Affected by Construction Site Discharges and Methods to Control Potential Pollutants Causing or Contributing to the Impairments None.

B. Impairment Sources and Prevention Construction sites can contribute to these impairments directly through the release of excess soil and/or nutrients within stormwater runoff. For this reason, proper sediment and erosion control BMPs should be implemented.

C. Site-Specific Requirements Proper sediment and erosion control BMPs will be implemented.

2.4. Critical Areas (CZC only)

No critical areas exist on-site or adjacent to the site.

ADC Project No. 12125 Page 17 10/02/2013

SECTION 3 – COMPLIANCE REQUIREMENTS

3.1. SWPPP Availability

A copy of the OS-SWPPP must be retained at the construction site or a nearby location easily accessible during normal business hours, from the date of commencement of construction actities to the date that final stabilization is reached.

If a location within the construction site is unavailable to store the OS-SWPPP when no personnel are present, notice of the plan's location, along with any updated contact information, must be posted near the main entrance at the construction site.

Contractors who have day-to-day operational control over OS-SWPPP implementation, must have a copy of this SWPPP available at a central location within the construction site for the use by all those identified as having responsiblities under the OS-SWPPP.

OS-SWPPPs must be made available upon request and at the time of a construction site inspection by EPA; DHEC; local government officials; and the Operator of a Municipal Separate Storm Sewer System

(MS4).

3.2. Pre-Construction Conferences

Prior to any construction activity, the Contractor shall schedule and organize an on-site Stormwater Pre- Construction Conference. Each contractor or subcontractor, who will work at the site, must attend this conference in person.

The Contractor shall invite the Contracting Officer and agencies listed below to the Stormwater Pre- Construction Conference. The Contractor must invite the noted agencies to the meeting at least 7 days prior to conducting the meeting.

SCDHEC EQC Regional Office Charleston – Region 7 EQC Field Office 1362 McMillan Ave., Suite 300 Charleston, SC 29405 Tel: 843-953-0150

Joint Base Charleston-Air Base

628 CES/CEPMF

210 W. Stewart Ave.

Joint Base Charleston, SC 29404 Contact: Charles Wannamaker Tel: 843-963-2705

3.3. Inspection Requirements

The General Contractor shall be responsible for all SWPPP inspections. Inspections shall include the following:

1. All areas of the site disturbed by construction activity and areas used for storage of materials that are exposed to precipitation;

2. All stormwater conveyance systems for any evidence of, or the potential for, pollutants entering these systems;

3. All BMPs identified in the OS-SWPPP;

4. All discharge locations to ascertain whether the implemented BMPs are effective in preventing the discharge of sediment from the site. Where discharge locations are inaccessible, nearby downstream locations must be inspected to the extent that such inspections are practicable; and

5. Locations where vehicles enter or exit the site must be inspected for evidence of off-site sediment tracking.

ADC Project No. 12125 Page 18 10/02/2013

Inspection Frequency After construction activities begin, inspections must be conducted at a minimum of at least once every calendar week and must be conducted until final stabilization is reached on all areas of the construction site. An inspection is recommended within 24 hours of the end of a storm event of 0.5 inches or greater.

Inspector Qualifications Inspections must be conducted by qualified personnel (provided by the General Contractor). “Qualified Personnel” means a person knowledgeable in the principles and practice of erosion and sediment controls who possesses the skills to assess conditions at the construction site that could impact stormwater quality and to assess the effectiveness of any BMPs selected to control the quality of stormwater discharges from the construction site. This person must be an individual who has been certified through a Construction Site Inspector Certification Course that has been approved by DHEC.

Inspections may also be conducted by a person with a registration equivalent to the registration of the preparer of the C-SWPPP (professional engineer).

3.4. Maintenance Requirements

Proper maintenance of post-construction water quality BMP’s and drainage systems is required to ensure they continue to function as designed and permitted. Maintenance activities shall be performed as follows:

System Maintenance Requirements Maintenance Frequency

A. Vegetated Areas 1. Mow Grass 1. Monthly

2. Remove all litter and debris 2. Monthly

3. Remove and replace dead or diseased vegetation

3. Semi-Annually

4. Replace / Replenish mulch. 4. Semi-Annually

5. Remove weeds. 5. Semi-Annually

6. Prune vegetation to maintain appearance 6. Semi-Annually

B. Storm Drainage System 1. Remove all litter and debris from pipes. 1. Annually

2. Remove sediment from drainage structure sumps

2. Annually, or when sump volume has been reduced by 50%.

C. Grass Lined Ditches and Swales 1. Mow swale slopes 1. Monthly

2. Remove all litter and debris 2. Monthly

3. Repair side slopes. 3. Annually

4. Remove sediment buildup within bottom of swale

4. Annually, or when swale volume has been reduced by 25%

D. Energy Dissipaters 1. Remove all litter and debris 1. Monthly

2. Repair erosion or damaged dissipaters. 2. Annually

3.5. Record Keeping

Any logs necessary to track the progress, compliance, modifications and those associated with the construction site. These logs may include, but are not limited to, a pre-construction conference log, an inspection log, a stabilization log, a rain log, a contractor log and/or any additional record keeping as deemed necessary by the Permittee, Contractor, DHEC, MS4, or an entity delegated under Regulation 72-300.

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3.6. Final Stabilization

Final site stabilization is achieved when perennial vegetative cover provides permanent stabilization with a density greater than 70 percent over the entire area to be stabilized by vegetative cover. This area is exclusive of areas that are covered with rock (crushed granite, gravel, etc.) or landscape mulch, paved or have a building or other permanent structure on them.

ADC Project No. 12125 10/02/2013

Appendix A – Stormwater Applications & Permits

1. NPDES CGP Coverage Letter

2. Approved Notice of Intent

3. Coastal Zone Consistency Certification

4. MS4 Approval Letter(s) w/ Approved Application

Appendix B – Maps (Vicinity, Quadrangle, FIRM, Aerial, Soils, Wetlands)

Appendix C – Contractor Certifications

5. Contractor Certification Form

6. Pre-Construction Conference Certification Form

7. Pre-Construction Conference Attendance Log

Appendix D – Inspection Log and Reports

1. SWPPP Inspection Log

2. NPDES Storm Water Construction Compliance Inspection Report

Appendix E – Rainfall Log and Reports

Appendix F – Additional Site Logs and Records

1. Contractor and Sub-Contractor Log

2. Modification Log

3. Soil Stabilization Log

Appendix G – Construction General Permit SCR100000

A copy of the NPDES General Permit for Stormwater Discharges from Construction Activities (SCR100000) can be found at the following address:

http://www.scdhec.gov/environment/water/swater/construction

Appendix A – Stormwater Applications & Permits

1. NPDES CGP Coverage Letter

2. Approved Notice of Intent

3. Coastal Zone Consistency Certification

4. MS4 Approval Letter(s) w/ Approved Application

Appendix B – Maps (Vicinity, Quadrangle, FIRM, Aerial, Soils, Wetlands)

Appendix C – Contractor Certifications

5. Contractor Certification Form

6. Pre-Construction Conference Certification Form

7. Pre-Construction Conference Attendance Log

SCDHEC, UST Management Division, 2600 Bull Street, Columbia, SC 29201, PHONE (803)898-7957 FAX (803) 896-6245 www.scdhec.gov lynnes Highlight

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.”

DHEC 0437 (10/2012)

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…