2020-05-20 SWPPP Documents.pdf

STORM WATER POLLUTION PREVENTION PLAN

for

United States Army Corps of Engineers and

United States Army Garrison West Point

Cyber and Engineering Academic Center

USAG West Point Orange County, New York

Prepared by:

Jacobs Engineering 412 Mt. Kemble Ave.

Suite 100S Morristown, New Jersey 07960

(973) 267-0555

May 2020

Kenneth Bienkowski, PE

NY License No. 076240-1 laclauk Stamp

United States Army Garrison West Point Cyber and Engineering Academic Center ii

TABLE OF CONTENTS

SECTION PAGE

1 DESCRIPTION OF THE WORK 1

1.1 Project Scope 1

1.2 Stormwater Permitting 1

1.3 NYSDEC Requirements 1

1.4 Stormwater Management Objectives 2

1.5 Pollution Prevention Measures 3

1.6 Pre and Post Development Conditions 3

2 SUMMARY OF GP-0-20-001 INFORMATION 5

2.1 General 5

2.2 Water Quality Contraventions 7

2.3 Other Permits 7

2.4 Construction Sequencing Schedule 7

3 EROSION AND SEDIMENT CONTROL MEASURES 8

3.1 General Construction Activity 8

3.2 Contractor's Responsibilities 9

3.3 Sensitive Areas/Receiving Waters 9

3.4 Typical Controls 9

3.5 Stabilization and Maintenance 10

3.6 Permanent Erosion and Sediment Controls 10

3.7 Additional Pollution Prevention Measures 10

3.8 Management of Concrete Washout 11

4 POST CONSTRUCTION STORMWATER MANAGEMENT MEASURES 13

4.1 Application of Acceptable Stormwater Management Practices 13

4.2 Stormwater Management Design 14

4.3 Maintenance Requirements 14

5 SITE ASSESSMENTS & INSPECTIONS 15

5.1 Requirements 15

6 REPORTING AND RETENTION OF RECORDS 18

United States Army Garrison West Point Cyber and Engineering Academic Center iii

LIST OF APPENDICES

Appendix No. Title

A Contract Drawings (under separate cover)

B Stormwater Permits SPDES General Permit GP-0-20-001

C Notice of Intent (NOI)

D MS4 SWPPP Acceptance Form

E References

F Stormwater Management Report

G Geotechnical Engineering Report

H Operation and Maintenance Manual

United States Army Garrison West Point Cyber and Engineering Academic Center (CEAC) Stormwater Pollution Prevention Plan May 2020

1 DESCRIPTION OF THE WORK01

1.1 Project Scope

The project consists of the construction of a new Cyber and Engineering Academic Center (CEAC) Building by the United States Army Corps of Engineers (USACE), New York District. The facility, located at the United Stated Army Garrison (USAG) West Point, will consist of a 53,000± SF building with a 2-level underground vehicular parking structure, an access drive, utility service extensions and relocations, and associated site/drainage improvements. Only a portion of the overall USAG West Point property, approximately 11.92 acres, will be analyzed for stormwater drainage calculations. This area consists of the entire onsite and adjacent offsite drainage area tributary to the CEAC project. The CEAC project is anticipated to disturb approximately 7.44 acres and will be used to analyze all WQv/RRv calculations. All remaining drainage for the parcel will maintain the existing drainage pattern. The existing and proposed site improvements are located within the Contract Drawings located in Appendix A. The Operator, as defined by the New York State Department of Environmental Conservation’s (NYSDEC) regulations, is the USAG West Point. It should be noted that the project will be phased to limit the soil disturbance and the largest excavation phase will disturb a total of 5.12 acres. While 5.12 acres will be disturbed at any one time, 0.87 of this is rock surface therefore the actual maximum soil disturbance at one time is anticipated to be less than 5 acres (4.25).

1.2 Stormwater Permitting

The NYSDEC issued Permit No. GP-0-20-001, SPDES General Permit for Stormwater Discharges from Construction Activities (General Permit) in January 2020, effective January 29, 2020, pursuant to Section 402 of the Clean Water Act. Construction activities disturbing greater than one acre of soil are required to obtain a discharge permit for stormwater. GP-0-20-001 requires the preparation of a Stormwater Pollution Prevention Plan (SWPPP) for the project prior to initiation of construction activities.

The SWPPP has been prepared in accordance with the requirements of the General Permit and the stormwater management has been designed in conformance with the requirements of the New York State Stormwater Management Design Manual dated January 2015 (NYS SWMDM).

1.3 NYSDEC Requirements

The New York State Stormwater Design Manual provides standards for the design of the Stormwater Management Practices (SMPs) to protect the waters of the State of New York from the adverse impacts of urban stormwater runoff. The manual is intended to establish specifications and uniform criteria for the practices that are part of a Stormwater Pollution Prevention Plan (SWPPP).

Projects that disturb (1) one acre or more of land are required to provide stormwater infiltration, quality, and quantity in accordance with the design manual. Below are the requirements that are associated with this project.

· Capture and treat the Water Quality Volume (WQv)

· Use Runoff Reduction (RR) techniques to provide a Runoff Reduction (RRv)

· Provide Stream Channel Protection Volume (CPv)

· Provide Overbank Control (Qp)

· Provide Extreme Flood Control (Qf)

· Utilize redevelopment techniques for exiting developed areas

For this project, open channel conveyance, discharge to filter strips or buffers, manufactured treatment devices, and an underground detention system have been implemented to meet the requirements of the NYSDEC Stormwater Design Manual.

The project is anticipated to disturb a total of 7.44 acres. It is anticipated that a maximum of 5.12 acres will be disturbed at any one time, however 0.87 acres of this area is rock surface. Therefore, the actual maximum soil disturbance at one time is anticipated to be less than 5 acres (4.25 acres).

1.4 Stormwater Management Objectives

The first stormwater management objective for this project is to control runoff and pollutants from the site during construction activities. This is done by providing temporary erosion and sediment control measures for the project that are in conformance with the New York State Standards and Specifications for Erosion and Sediment Control, published by the Empire State Chapter of the Soil and Water Conservation Society, November 2016. Soil erosion and sediment control measures will reduce or eliminate erosion and sediment loading to water bodies during construction and control the impact of runoff on water quality.

The second stormwater management objective is to provide permanent measures to control stormwater runoff quality and quantity after construction is complete. This objective is achieved by using green infrastructure techniques, ‘standard’ and ‘alternative’ stormwater management practices listed in section

3.3 of Chapter 3 of the NYS Stormwater Management Design Manual (NYS SWMDM) using the design guidance for the standard practices as described in Chapter 6.

1.5 Pollution Prevention Measures

In addition to the soil erosion and sediment control plan, measures will also be implemented during construction to prevent the discharge of pollutants into surface waters. The contractor shall implement and adhere to a waste management plan in accordance with USAG West Point guidelines. The plan will indicate solid waste and recycling procedures, waste hauling, material storage locations, etc.

1.6 Pre and Post Development Conditions

The existing site conditions for the subject property are illustrated on the “Existing Drainage Area Map” included within the appendix of this report. The map is based on a topographic survey prepared by MJ

Engineering and Land Surveying, P.C., dated March 2018.

The existing site is currently developed and consists of numerous buildings, bituminous asphalt pavement, grass and wooded areas with exposed rock ledges and boulders. The project area is bound by Thayer Road to the east with Cullum Road and the Hudson River beyond; Building 606 to the north with various Barracks beyond; a bituminous asphalt parking area to the west with a wooded and steeply upward sloped area beyond; and residential Quarters to the south (Quarters #5 through #9). An area between Quarters #5 and Building 606 was the previous location of the Central apartment structure, which has since been demolished. The area is currently being used as a construction trailer location for the on-going renovations of various Barracks. Bituminous asphalt access roads (Wilson Road) and vehicular parking areas traverse the project site.

The project area is steeply sloped from west to east. A grade change of approximately 70’ exists from the upper wooded area toward the west and Thayer Road toward the east. Numerous areas of exposed impervious rock ledges and boulders are present within this area. A bituminous asphalt walkway (Billy Goat Trail) traverses the wooded area and provides pedestrian access from a residential area to the west to Building 606. An existing stormwater management system, consisting of numerous stormwater inlets, manholes, and various sized piping, is located throughout the project area. All stormwater is eventually conveyed to the final discharge, eventually being the Hudson River.

On-site investigations indicate numerous areas of exposed bedrock ledge at existing rock-cut areas and throughout the surface area. A geotechnical investigation performed by GeoConcepts Engineering, Inc.

in April 2018 indicates bedrock is present at the surface and at a shallow depth below the surface. This bedrock has been identified as a hard-dense granite. Based on a review of the Natural Resources Conservation Service Web Soil Survey for Orange County, the subject parcel contains ROC (Rock Outcrop

– Hollis complex, sloping) and ROD (Rock Outcrop – Hollis complex, 15 to 35 percent slopes), all of which have been delineated in the Soil Survey Report located within the appendix of this report. In accordance with the Web Soil Survey, all onsite soils have been classified as “D” type soils. All existing runoff calculations were performed using the SCS Method with a runoff CN of 77 for woods/brush areas, 84 for pervious areas, and 98 for impervious areas (includes exposed bedrock).

The proposed improvements include the construction of a new 53,000± SF CEAC Building with a 2-level underground vehicular parking structure, an access drive with an underground vehicle parking area, a concrete service yard on the west side of the building, utility relocations and extension, and associated site/drainage improvements. The improvements will require removal of the bituminous parking and access roads throughout the project area, rock excavation creating an exposed rock face that exceeds 70’ in various locations, numerous utility relocations, and clearing of wooded areas. An additional 30’ – 40’ of rock excavation is required for the underground parking structure. All rock excavation shall be either processed for reuse or removed from the site by the contractor. The drainage improvements include two

(2) vegetated swales, storm piping, four (4) stormwater water quality units, and a 17,643 CF underground detention basin consisting of 351’ LF of 96” corrugated metal pipe (CMP). The existing and proposed site conditions for the subject property are illustrated on the Contract Drawings included within Appendix A.

The drawings are based on a topographic survey prepared by MJ Engineering and Land Surveying, P.C., dated March 2018.

2 SUMMARY OF GP-0-20-001 INFORMATION

2.1 General

Information required by GP-0-20-001 is as follows:

Project Location USAG West Point West of the Thayer Road and Cullum Road intersection, Orange County, New York

Project The proposed improvements include the construction of a new 53,000± SF CEAC Building with a 2-level underground vehicular parking structure, an access drive with an underground vehicle parking area, a concrete service yard on the west side of the building, utility relocations and extension, and associated site/drainage improvements. The improvements will require removal of the bituminous parking and access roads throughout the project area, rock excavation creating an exposed rock face that exceeds 70’ in various locations, numerous utility relocations, and clearing of wooded areas. An additional 30’ – 40’ of rock excavation is required for the underground parking structure. All rock excavation shall be either processed for reuse or removed from the site by the contractor. The drainage improvements include two (2) vegetated swales, storm piping, four (4) stormwater water quality units, and a 17,643 CF underground detention basin consisting of 351’ LF of 96” corrugated metal pipe (CMP).

Site Map See Contract Drawings

Estimated Disturbed Area 7.44 acres total soil disturbance for the project area.

Disturbance is Greater than 5 acres at any one time The largest excavation phase will disturb a total of 5.12 acres. While 5.12 acres will be disturbed at any one time, 0.87 of this is rock surface therefore the actual maximum soil disturbance at one time is anticipated to be less than 5 acres (4.25 acres).

Existing Surface The site is currently developed/maintained with a mixture of vegetated fill areas, exposed rock ledges/surfaces, trees, grassy areas, and concrete/bituminous paved walkways and parking areas/roadways

Wetlands/Water bodies The closest waterbody is the Hudson River, approximately 600’ east and 165’ downslope of the project site.

Stockpile Locations Within approved areas

Soils On-site investigations indicate numerous areas of exposed bedrock ledge at existing rock-cut areas and throughout the surface area. A geotechnical investigation performed by GeoConcepts Engineering, Inc.

in April 2018 indicates bedrock is present at the surface and at a shallow depth below the surface. This bedrock has been identified as a hard-dense granite. Based on a review of the Natural Resources Conservation Service Web Soil Survey for Orange County, the subject parcel contains ROC (Rock Outcrop – Hollis complex, sloping) and ROD (Rock Outcrop – Hollis complex, 15 to 35 percent slopes), all of which have been delineated in the Soil Survey Report located within the appendix of this report. In accordance with the Web Soil Survey, all onsite soils have been classified as “D” type soils. All existing runoff calculations were performed using the SCS Method with a runoff CN of 77 for woods/brush areas, 84 for pervious areas, and 98 for impervious areas (includes exposed bedrock).

Phasing See SWPPP Section 2.4

Erosion Control Plan See SWPPP Chapter 3, and Figures / Specifications

On-site storage Construction equipment and stockpiling of materials (e.g. soils, building materials). Location of materials to be stockpiled will be approved by the Contracting Officer and the catch basins in the area will be protected to prevent soil erosion and sediment runoff. Stockpiled soil will be also be surrounded by silt fencing. Loose material shall be tarped prior to any storm event to minimize loss of material.

2.2 Water Quality Contravention

Part I B of the General Permit prohibits any person to cause or contribute to a condition that will cause contravention of any water quality standards that are contained in the Rules and Regulations of the State of New York. Any violations of water quality standards will be considered by the NYSDEC to be violations of the SPDES Permit and its accompanying regulations. If any violations are incurred as a result of the Contractor’s actions, it will be the responsibility of the Contractor to correct the violation to the satisfaction of the USAG West Point.

2.3 Other Permits

No other environmental permits are required for this work.

2.4 Construction Sequencing Schedule

The project is scheduled to initiate construction on or about October 2020. The construction is scheduled to take approximately four years to complete. The selected contractor will be required to submit a proposed construction progress schedule including the locations of his proposed temporary and permanent erosion control measures, the location of his debris and rubbish disposal area, and the equipment and material storage area and any stockpile locations (showing any needed pollution prevention measures).

The recommended sequence for the installation of soil erosion and sediment control measures is described in Section 3 and approved control measures are shown on the Contract Drawings.

3 EROSION AND SEDIMENT CONTROL MEASURES

3.1 General Construction Activity

Stockpiling of excavated material is permitted with the prior approval of the location(s) by the Contracting Officer. Approval of such locations does not relieve the Contractor from its responsibilities under this

SWPPP.

The following general construction sequence is provided as a guide to the proper sequencing of soil erosion and sediment control features.

1. Install Soil Erosion and Sediment Control Practices, including Filter Sock/Silt Fences and Inlet Filters around all existing drainage structures within the work area prior to the disturbance of soil.

Tree protection shall be installed around individual or groups of trees to remain.

2. Site clearing and grubbing.

3. Demolish site features and existing utilities to be removed.

4. Mass rock excavation from the project area.

5. Construct the new utilities (storm drains, underground basin, below grade utilities, chilled water lines, etc.).

6. Install Soil Erosion and Sediment Control Practices, including Inlet Filters and Filter Sock/Silt Fence around all new drainage structures within the work area.

7. Building construction.

8. Final bituminous pavement.

9. Permanently stabilize all disturbed areas in accordance with the contract documents.

10. Remove Soil Erosion and Sediment Control Practices in accordance with the contract documents.

It is anticipated that the construction will be conducted in two phases. Phase I consists of clearing, grubbing, and demolition of site features and utilities to be removed. Phase II consists of mass rock excavation from the construction area and building/utility/site feature construction. The contractor shall prepare and submit to the Contracting Officer a detailed sequence of construction and project phasing plan that defines maximum disturbed area per phase and shows required cuts and fills as required.

During the above sequence of activities, the trained contractor and the Engineer will conduct inspections to ensure that the soil erosion and sediment control features are installed and maintained in accordance with the Contract Documents and the NYS Stormwater Requirements. The qualified inspector will also inspect the installation and maintenance of the soil erosion and sediment control measures during the weekly inspection and include the information in the report. An inspection is also required after any storm event and after any time off from the site (weekend, holiday, etc.). A copy of the project Soil Erosion and Sediment measures, notes, and details are located within the Contract Drawings.

3.2 Contractor's Responsibilities

The Contractor and all subcontractors will be required to certify to fully comply with this SWPPP. NYSDEC requires that there should be at least one trained contractor responsible for implementing the SWPPP and having at least one of the identified, trained individuals on site daily when soil disturbance activities are being performed. The NYSDEC SPDES General Permit GP-0-20-001 identifies a trained inspector as an employee from the contracting (construction) company, identified in Part III.A.6., that has received four

(4) hours of Department endorsed training in proper erosion and sediment control principles from a Soil and Water Conservation District, or other Department endorsed entity. After receiving the initial training, the trained contractor shall receive four (4) hours of training every three (3) years. It can also mean an employee from the contracting (construction) company, identified in Part III.A.6., that meets the qualified inspector qualifications (e.g. licensed Professional Engineer, Certified Professional in Erosion and Sediment Control (CPESC), Registered Landscape Architect, New York State Erosion and Sediment Control Certificate Program holder, or someone working under the direct supervision of, and at the same company as, the licensed Professional Engineer or Registered Landscape Architect, provided they have received four (4) hours of Department endorsed training in proper erosion and sediment control principles from a Soil and Water Conservation District, or other Department endorsed entity). The trained contractor is responsible for the day to day implementation of the SWPPP.

3.3 Sensitive Areas/Receiving Waters

The proposed CEAC building is located within an existing developed area of the campus and bound by existing buildings, bituminous asphalt parking areas/roadways, and exposed rock ledges. There are no sensitive areas within the project limits. The Hudson River is approximately 600’ east and 165’ downslope of the project site. The proposed site improvements shall not affect any of these areas. Any disturbance to these areas will require restoration per NYSDEC and the Contracting Officer.

3.4 Typical Controls

Specific means and methods of soil erosion and sediment control during construction are at the discretion of the Contractor providing that they are in conformity with the Erosion and Sediment Control Plan. This plan will depict the locations of the control measures and the schedule for their implementation. Erosion control measures may include, but are not limited to, the following:

· Stabilized Construction Entrance

· Staked Hay Bales

· Staked Filter Sock or Silt Fence

· Inlet Filters for Inlet Structures

· Temporary Seeding

· Soil Erosion Matting

· Paved streets to be broom clean at the end of the day

· Use of a street sweeper as needed due to soil tracking

· Dust Control using water shall be employed

Products to be used shall be as specified in the New York State Standards and Specification for Erosion and Sediment Control prepared by the NYSDEC and as approved by the USACE prior to construction.

3.5 Stabilization and Maintenance

In areas where soil disturbance activity has temporarily or permanently ceased, the application of soil stabilization measures must be initiated by the end of the next business day and completed within seven

(7) days from the date the current soil disturbance activity ceased. The soil stabilization measures selected shall be in conformance with the technical standard, New York State Standards and Specifications for Erosion and Sediment Control, dated November 2016.

Filter Sock/Silt Fence, stone outlet structures, check dams, and hay bales shall have sediment removed when the sediment reaches 50% of the height of the soil erosion and sediment control measure. Any soil and erosion control measures that have been damaged shall be immediately replaced.

3.6 Permanent Erosion and Sediment Controls

Upon completion of construction, the project site will have a total of 2.08 acres of impervious pavement and exposed rock ledge area within the disturbed area. The project will implement a combination of vegetated swales, stormwater planters, stormwater filters, and an underground detention system to manage runoff and control erosion and sediment after the completion of construction. Pervious areas that will remain pervious will be stabilized with vegetation as indicated on the Contract Drawings. The stormwater management practices for the project have been designed to manage the stormwater and improve the water quality by the amount required in the January 2015 NYS SWMDM Chapter 4. Appendix F presents the hydrologic analysis of the post construction stormwater management practices.

3.7 Additional Pollution Prevention Measures

In addition to the soil erosion and sediment control measures, the Contractor will be required to implement additional pollution prevention measures to prevent contravention of water quality and to implement measures to prevent runoff from stockpiles.

Soils that are either excavated and stockpiled or brought on site to be used as backfill will be managed to prevent soil erosion and sedimentation. At a minimum, the stockpiles will be surrounded with silt fencing to prevent runoff of soil and sediment from the pile. If encountered, petroleum contaminated soils will be placed on plastic to prevent runoff of contaminated onto the surrounding areas in addition to being surrounded by a silt fence. If catch basins or other conveyances to surface waters are in the stockpile area, they will be protected with soil erosion and sediment control measures (e.g. inlet filters or hay bales).

Materials, other than soil, that will be stockpiled (i.e. not planned for use in the near-term future) are required to be protected in order to prevent the runoff of materials from pile that have the potential to pollute surface waters. Loose material shall be tarped prior to any storm event to minimize loss of material.

3.8 Management of Concrete Washout

The concrete washout area should be located at least 50 feet away from any storm drain, should be located at least 200 feet away from surface water and should not be located on grassy/unpaved areas.

Cleaning/washout of concrete delivery vehicles shall be limited to cleaning the chutes with as little water as possible. The water shall discharge into one of the following:

For concrete deliveries exceeding 30 CY over a 1-week period provide:

1. A portable, self-contained and watertight roll-off metal bin/container that is delivered and collected by a firm that specializes in concrete washout containers and recycling

For periodic concrete deliveries less than 30 CY over a 1-week period the following wash-out container is acceptable:

1. A heavy-duty, woven polypropylene outer bag with 6-mm corrugated plastic inner walls or a 6-mm polyethylene liner

2. A water resistant corrugated box and a 6-mm poly liner

3. A reinforced PVC, UV and weather resistant formed structure

The washout structure shall be sturdy enough for pick-up and removal once the concrete has hardened.

It shall be placed and secured in a level area away from any storm drains and watercourses. Once the concrete has hardened, any remaining water shall be pumped from the washout and disposed of at a facility permitted to receive liquid waste. The solid concrete residue shall be removed from the site and disposed of in accordance with local regulations. Under no circumstances shall the drum of the truck be emptied of excess concrete and/or washed-out on site. Similar procedures shall be adhered to for washout of portable cement and concrete mixers.

Submit shop drawings of the proposed washout container and location for approval prior to any concrete delivery.

The Contractor shall seal all the catch basins in the area of the concrete washout area prior to use. When the washout has filled to 70% of capacity, the accumulated materials shall be removed. Hardened material may be removed and reused or hauled off-site for disposal. Any remaining liquids will be shipped to a disposal facility permitted to accept concrete washout, concrete slurry or concrete-containing water. The Contractor shall also collect the water in the area of the catch basin and any ponded water in the vicinity of the concrete washout pit and ship the liquid to a disposal facility permitted to accept concrete washout, concrete slurry or concrete-containing water.

Prior to any predicted rainfall, the Contractor shall remove all liquid from the concrete washout area and dispose of the liquid at a permitted disposal facility. If practicable, the Contractor shall also cover the concrete washout area prior to any predicted rainfall. The Contractor shall inspect the concrete washout area following any rainfall to verify that the concrete washout area has not overfilled and that there is no leakage.

The prefabricated washout container, the surrounding areas and the catch basins shall be inspected by the Trained Contractor as part the daily inspection. The Qualified Inspector shall inspect the concrete washout pit and/or prefabricated washout container, the surrounding areas and the catch basins during the twice weekly inspection and include the results of the inspection in the inspection report. If any deficiency is seen by either the Trained Contractor or the Qualified Inspector, all work shall immediately be stopped, the Contracting Officer notified, the deficiency corrected, and the concrete washout pit or prefabricated washout container inspected by the Contracting Engineer. Only after the Contracting Officer approves the correction of the deficiency, the Contractor shall be allowed to resume work and use of the prefabricated washout container.

4. POST CONSTRUCTION STORMWATER MANAGEMENT MEASURES

4.1 Application of Acceptable Stormwater Management Practices Development of the site will include post construction stormwater management measures in conformance with the NYS SWMDM. More specifically, the design provides water quality, captures and maintains the required WQv, and provides reductions in peak flow from the site.

The Water Quality Volume (WQv) is intended to improve water quality by capturing and treating runoff from small, frequent storm events that tend to contain higher pollutant levels. New York has defined the WQv as the volume of runoff generated from the entire 90th percentile rain event. The WQv is directly related to the amount of impervious cover constructed at a site. Contour lines of the 90% rainfall event are presented in Figure 4.1 of the Stormwater Design Manual. The 90% rainfall event for this project is 1.40”.

Runoff reduction (RRv) shall be achieved by infiltration, groundwater recharge, reuse, recycle, evaporation/evapotranspiration of 100 percent of the post-development water quality volume (WQv) to replicate pre-development hydrology by maintaining pre-construction infiltration, peak runoff flow, discharge volume, as well as minimizing concentrated flow by using runoff control techniques to provide treatment in a distributed manner before runoff reaches the collection system. This requirement can be accomplished by application of on-site green infrastructure techniques, standard stormwater management practices with runoff reduction capacity, and good operation and maintenance.

Stream Channel Protection Volume Requirements (CPv) are designed to protect stream channels from erosion. In New York State this goal is accomplished by providing 24-hour extended detention of the one-year, 24-hour storm event, remained from runoff reduction. Detention ponds or underground detention systems and vaults are methods to meet the CPv requirement. The rainfall depth for the one-year, 24-hour storm event has been determined to be 2.75” based on information provided in Figure 4.2 of the NYDEC Stormwater Design Manual.

Overbank control requires storage to attenuate the post development 10-year, 24-hour peak discharge rate (Qp) to predevelopment rates. The rainfall depth for the 10-year, 24-hour storm event has been determined to be 5.00” based on information provided in Figure 4.3 of the NYDEC Stormwater Design Manual.

Extreme flood control requires storage to attenuate the post development 100-year, 24-hour peak discharge rate (Qf) to predevelopment rates. The rainfall depth for the 100-year, 24-hour storm event has been determined to be 9.25” based on information provided in Figure 4.4 of the NYDEC Stormwater Design Manual.

For this project, open channel conveyance, discharge to filter strips and buffers, manufactured treatment devices, and an underground detention system have been implemented to meet the requirements of the NYSDEC Stormwater Design Manual. The results are summarized within the Stormwater Management Report located in Appendix F.

4.2 Stormwater Management Design

The methodology utilized to design the subject stormwater management system follows all jurisdictional agency regulations. Specifically, the proposed design was developed for the subject site utilizing requirements outlined within the NYDEC Stormwater Management Design Manual. All existing and proposed runoff calculations were performed using the SCS Method. The time of concentration (Tc) was calculated using a minimum 10 minutes for the drainage areas. Hydrographs were generated for each land type under the existing and proposed conditions and were created with Hydraflow (stormwater design software).

The drainage improvements include two (2) vegetated swales, storm piping, four (4) manufacturer treatment devices for water quality, and an underground detention basin consisting of 96” corrugated metal pipe. Where feasible, open channel conveyance was used to convey the overland stormwater into the appropriate management facility and provide a reduction in the overall WQv/RRv requirement. A stormwater quality filter has been designed to treat a portion of the volume from the NYSDEC water 90th percentile storm. An underground detention basin, consisting of 351 LF of 96” CMP, provides approximately 17,643 CF of storage. The basin has been designed to provide quantity reductions for the project site. Hydrologic design calculations, modeling and details are provided within the Stormwater Management Report located in Appendix F.

4.3 Maintenance Requirements

Under normal operating conditions, open channel conveyance, manufactured treatment devices, and the underground detention basin require routine maintenance. Sediment build-up exceeding one-inch in the open conveyance must be removed and replaced with fresh material. Trash and debris shall be removed as well. After construction, the areas will be vegetated with approved grass and plantings. Typical maintenance for the channel will consist of mowing and spot treating areas for invasive species.

Maintenance of the manufactured treatment devices and underground detention basin shall include monthly inspections and vacuuming on a yearly or as-needed basis. A qualified contractor specializing in the repair/maintenance of the stormwater filter media cartridges shall be retained to provide regular scheduled inspections/cleaning. The Operation and Maintenance Manual to be implemented at the site is included within Appendix H of this SWPPP.

5 SITE ASSESSMENTS & INSPECTIONS

5.1 Requirements

5.1.1. The operator shall have a qualified inspector1 inspect all erosion and sediment control practices to ensure integrity and effectiveness, all post-construction stormwater management practices under construction to ensure that they are constructed in conformance with the SWPPP, all areas of disturbance that have not achieved final stabilization, and all points of discharge from the construction site.

The qualified inspector and US Army Garrison West Point Stormwater Manager shall assess the site prior to the commencement of construction and certify in an inspection report that the appropriate erosion and sediment controls described in the SWPPP and required by Part III of GP- 0-20-001 have been adequately installed or implemented to ensure overall preparedness of the site for the commencement of construction. Following the commencement of construction, site inspections shall be conducted by the qualified inspector at least every seven (7) calendar days, within 24 hours of the end of a storm event of 0.5 inches or greater, and after any time off from the site (weekend, holiday, etc.). During each inspection, the qualified inspector shall record the following information:

1. Date and time of inspection;

2. Name and title of person(s) performing inspection;

3. A description of the weather and soil conditions (e.g. dry, wet, saturated) at the time of the inspection;

4. A description of the condition of the runoff at all points of discharge from the construction site. This shall include identification of any discharges of sediment from the construction site. Include discharges from conveyance systems (i.e. pipes, culverts, ditches, etc.) and overland flow;

5. A description of the condition of the natural surface waterbodies located within, or

1 A qualified inspector is a person that is knowledgeable in the principles and practices of erosion and sediment control, such as a licensed Professional Engineer, Certified Professional in Erosion and Sediment Control (CPESC), licensed Landscape Architect, or other Department endorsed individual(s). It also means someone working under the direct supervision of the licensed Professional Engineer or licensed Landscape Architect, provided that person has training in the principles and practices of erosion and sediment control. Training in the principles and practices of erosion and sediment control means that an individual performing a site inspection has received four (4) hours of training, endorsed by the NYSDEC, from a Soil and Water Conservation District, CPESC, Inc. or other NYSDEC endorsed entity in proper erosion and sediment control principles. After receiving the initial training, an individual working under the direct supervision of the licensed Professional Engineer or licensed Landscape Architect shall receive four (4) hours of training every three (3) years.

immediately adjacent to, the property boundaries of the construction site which receive runoff from disturbed areas. This shall include identification of any discharges of sediment to the surface waterbody;

6. Identification of all erosion and sediment control practices and pollution prevention measures that need repair or maintenance;

7. Identification of all erosion and sediment control practices that were not installed properly or are not functioning as designed and need to be reinstalled or replaced;

8. Description and sketch of areas with active soil disturbance activity, areas that have been disturbed but are inactive at the time of inspection, and areas that have been stabilized (temporary and/or final) since the last inspection;

9. Current phase of construction of all post-construction stormwater management practices and identification of all construction that is not in conformance with the SWPPP and technical standards;

10. Corrective action(s) that must be taken to install, repair, replace or maintain erosion and sediment control practices and pollution prevention measures; and to correct deficiencies identified with the construction of the post-construction stormwater management practice(s);

11. Identification and status of all corrective actions that were required by previous inspection; and

12. Digital photographs, with the date stamp, that clearly show the condition of all practices that have been identified as needing corrective actions. The qualified inspector shall attach paper color copies of the digital photographs to the inspection report being maintained onsite within seven (7) calendar days of the date of the inspection. The qualified inspector shall also take digital photographs, with date stamp, that clearly show the condition of the practice(s) after the corrective action has been completed. The qualified inspector shall attach paper color copies of the digital photographs to the inspection report that documents the completion of corrective action work within seven

(7) calendar days of that inspection.

5.1.2 Within one business day of the completion of an inspection, the qualified inspector shall notify the owner or operator and appropriate contractor (or subcontractor) identified in the certification form of any corrective actions that need to be taken. The contractor (or subcontractor) shall begin implementing the corrective actions within one business day of this notification and shall complete the corrective actions in a reasonable time frame.

5.1.3 All inspection reports shall be signed by the qualified inspector. Pursuant to Part II.C.2. of GP-0- 20-001, the inspection reports shall be maintained on site with the SWPPP, NOI and NOI Acknowledgement Letter. Digital or hard copies, accessible to any employee, shall be kept at the jobsite.

5.1.4 Prior to filing of the Notice of Termination (NOT) or the end of permit term, the operator shall have the qualified inspector and the US Army Garrison West Point Stormwater Manager perform a final site inspection. The qualified inspector and Stormwater Manager shall certify that all disturbed areas have achieved final stabilization; and all temporary, structural erosion and sediment control measures have been removed; and that all post-construction stormwater management practices have been constructed in conformance with the SWPPP. The NOT is reviewed and approved by US Army Garrison West Point DPW EMD and sent to the Contractor for signature of the “Final Stabilization” and “Post-Construction Stormwater Management Practice” certification statements on the NOT.

6 REPORTING AND RETENTION OF RECORDS

The operator shall update the SWPPP with the inspection and repair reports generated during the construction activities. If any modifications to the SWPPP are required, the document will be updated as necessary.

After the site is stabilized and the post construction stormwater management controls are installed and operating, a Notice of Termination (NOT) is reviewed and approved by US Army Garrison West Point DPW EMD and sent to the Contractor for signature of the “Final Stabilization” and “Post-Construction Stormwater Management Practice” certification statements on the NOT. The documents are then submitted to the NYSDEC and the SWPPP will be finalized with the NOT and kept on file for at least five

(5) years.

The operator shall retain a copy of the NOI, SWPPP, certification for the Qualified Inspector(s) and/or Qualified Profession(s), and any inspection reports that were prepared in conjunction with the SWPPP, for a period of at least five (5) years from the date that the site achieves final stabilization and the NOI is submitted.

APPENDIX A – Contract Drawings (under separate cover)

APPENDIX B – Stormwater Permits

SPDES General Permit for Stormwater Discharges from Construction Activities

GP-0-20-001

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NEW YORK STATE

DEPARTMENT OF ENVI RONMENTAL CONSERVATION

SPDES GENERAL PERMIT

FOR STORMWATER D¡SCHARGES

From

CONSTRUCTION ACTIVITY

Permit No. GP- 0-20-001 lssued Pursuant to Article 17, Titles 7, I and Article 70 of the Environmental Conservation Law

Effective Date: January 29,2020 Expiration Date: January 28,2025

John J. Ferguson

Chief Permit Administrator

/^ zZ -Z-ö uthorized Signature Date

Address: NYS DEC Division of Environmental Permits 625 Broadway, 4th Floor Albany, N.Y. 12233-1750

I

PREFACE

Pursuant to Section 402 of the Clean Water Act (“CWA”), stormwater discharges from certain construction activities are unlawful unless they are authorized by a National Pollutant Discharge Elimination System (“NPDES”) permit or by a state permit program.

New York administers the approved State Pollutant Discharge Elimination System (SPDES) program with permits issued in accordance with the New York State Environmental Conservation Law (ECL) Article 17, Titles 7, 8 and Article 70.

An owner or operator of a construction activity that is eligible for coverage under this permit must obtain coverage prior to the commencement of construction activity.

Activities that fit the definition of “construction activity”, as defined under 40 CFR

122.26(b)(14)(x), (15)(i), and (15)(ii), constitute construction of a point source and therefore, pursuant to ECL section 17-0505 and 17-0701, the owner or operator must have coverage under a SPDES permit prior to commencing construction activity. The owner or operator cannot wait until there is an actual discharge from the construction site to obtain permit coverage.

*Note: The italicized words/phrases within this permit are defined in Appendix A.

I

NEW YORK STATE DEPARTMENT OF ENVIRONMENTAL CONSERVATION

SPDES GENERAL PERMIT FOR STORMWATER DISCHARGES FROM

CONSTRUCTION ACTIVITIES

Table of Contents

Part 1. PERMIT COVERAGE AND LIMITATIONS

A. Permit Application

B. Effluent Limitations Applicable to Discharges from Construction Activities C. Post-construction Stormwater Management Practice Requirements D. Maintaining Water Quality E. Eligibility Under This General Permit

F. Activities Which Are Ineligible for Coverage Under This General Permit Part II. PERMIT COVERAGE

A. How to Obtain Coverage

B. Notice of Intent (NOI) Submittal C. Permit Authorization

D. General Requirements For Owners or Operators With Permit Coverage E. Permit Coverage for Discharges Authorized Under GP-0-15-002 F. Change of Owner or Operator

Part III. STORMWATER POLLUTION PREVENTION PLAN (SWPPP) A. General SWPPP Requirements

B. Required SWPPP Contents C. Required SWPPP Components by Project Type

Part IV. INSPECTION AND MAINTENANCE REQUIREMENTS A. General Construction Site Inspection and Maintenance Requirements

B. Contractor Maintenance Inspection Requirements C. Qualified Inspector Inspection Requirements

Part V. TERMINATION OF PERMIT COVERAGE

A. Termination of Permit Coverage Part VI. REPORTING AND RETENTION RECORDS

A. Record Retention

B. Addresses Part VII. STANDARD PERMIT CONDITIONS

A. Duty to Comply B. Continuation of the Expired General Permit C. Enforcement

D. Need to Halt or Reduce Activity Not a Defense E. Duty to Mitigate

F. Duty to Provide Information G. Other Information H. Signatory Requirements I. Property Rights J. Severability

K. Requirement to Obtain Coverage Under an Alternative Permit

L. Proper Operation and Maintenance M. Inspection and Entry N. Permit Actions O. Definitions P. Re-Opener Clause

Q. Penalties for Falsification of Forms and Reports R. Other Permits

APPENDIX A – Acronyms and Definitions Acronyms Definitions

APPENDIX B – Required SWPPP Components by Project Type

Table 1 Table 2

APPENDIX C – Watersheds Requiring Enhanced Phosphorus Removal

APPENDIX D – Watersheds with Lower Disturbance Threshold APPENDIX E – 303(d) Segments Impaired by Construction Related Pollutant(s) APPENDIX F – List of NYS DEC Regional Offices

(Part I)

Part 1. PERMIT COVERAGE AND LIMITATIONS

A. Permit Application

This permit authorizes stormwater discharges to surface waters of the State from the following construction activities identified within 40 CFR Parts 122.26(b)(14)(x), 122.26(b)(15)(i) and 122.26(b)(15)(ii), provided all of the eligibility provisions of this permit are met:

1. Construction activities involving soil disturbances of one (1) or more acres;

including disturbances of less than one acre that are part of a larger common plan of development or sale that will ultimately disturb one or more acres of land; excluding routine maintenance activity that is performed to maintain the original line and grade, hydraulic capacity or original purpose of a facility;

2. Construction activities involving soil disturbances of less than one (1) acre where the Department has determined that a SPDES permit is required for stormwater discharges based on the potential for contribution to a violation of a water quality standard or for significant contribution of pollutants to surface waters of the State.

3. Construction activities located in the watershed(s) identified in Appendix D that involve soil disturbances between five thousand (5,000) square feet and one

(1) acre of land.

B. Effluent Limitations Applicable to Discharges from Construction Activities

Discharges authorized by this permit must achieve, at a minimum, the effluent limitations in Part I.B.1. (a) – (f) of this permit. These limitations represent the degree of effluent reduction attainable by the application of best practicable technology currently available.

1. Erosion and Sediment Control Requirements - The owner or operator must select, design, install, implement and maintain control measures to minimize the discharge of pollutants and prevent a violation of the water quality standards. The selection, design, installation, implementation, and maintenance of these control measures must meet the non-numeric effluent limitations in Part I.B.1.(a) – (f) of this permit and be in accordance with the

New York State Standards and Specifications for Erosion and Sediment

Control, dated November 2016, using sound engineering judgment. Where control measures are not designed in conformance with the design criteria included in the technical standard, the owner or operator must include in the

Stormwater Pollution Prevention Plan (“SWPPP”) the reason(s) for the

(Part I.B.1) deviation or alternative design and provide information which demonstrates that the deviation or alternative design is equivalent to the technical standard.

a. Erosion and Sediment Controls. Design, install and maintain effective erosion and sediment controls to minimize the discharge of pollutants and prevent a violation of the water quality standards. At a minimum, such controls must be designed, installed and maintained to:

(i) Minimize soil erosion through application of runoff control and soil stabilization control measure to minimize pollutant discharges;

(ii) Control stormwater discharges, including both peak flowrates and total stormwater volume, to minimize channel and streambank erosion and scour in the immediate vicinity of the discharge points;

(iii) Minimize the amount of soil exposed during construction activity;

(iv) Minimize the disturbance of steep slopes;

(v) Minimize sediment discharges from the site;

(vi) Provide and maintain natural buffers around surface waters, direct stormwater to vegetated areas and maximize stormwater infiltration to reduce pollutant discharges, unless infeasible;

(vii) Minimize soil compaction. Minimizing soil compaction is not required where the intended function of a specific area of the site dictates that it be compacted;

(viii) Unless infeasible, preserve a sufficient amount of topsoil to complete soil restoration and establish a uniform, dense vegetative cover; and

(ix) Minimize dust. On areas of exposed soil, minimize dust through the appropriate application of water or other dust suppression techniques to control the generation of pollutants that could be discharged from the site.

b. Soil Stabilization. In areas where soil disturbance activity has temporarily or permanently ceased, the application of soil stabilization measures must be initiated by the end…