STORMWATER POLLUTION PREVENTION PLAN

FOR

CONSTRUCTION ACTIVITIES

For

SUNYIT Prevention Services
Town of Marcy, Oneida County, New York

Prepared for:

Spring 2007 Capstone

Prepared by:

Tom Phillips

Jeremy Kemak

P.O. Box 13050

Utica, New York13504

April 2, 2007

Page 1

SWPPP for Construction Activities

Table of Contents

Introduction ...... Page 3

Proposed Site Development Information...... Page 3

Background Information ...... Page 3

Pre-Developed Conditions...... Page 3

Post-Developed Conditions ...... Page 4

Comparison of Pre-Development and Post-Development Runoff ConditionsPage 4

Methodology...... Page 5

Water Quality...... Page 6

Channel Protection ...... Page 6

Peak Discharge Calculation Summary...... Page 6

Storm Water Management System...... Page 7

Storm Water Management...... Page 8

Erosion and Sediment Control Requirements ...... Page 8

Temporary Erosion and Sediment Control Facilities...... Page 8

Permanent Erosion and Sediment Control Facilities ...... Page 8

Construction Schedule and Sequence...... Page 9

Construction Sequence...... Page 10

Inspection Procedures and Maintenance...... Page 11

Construction Site Wastes...... Page 12

Certification of Storm Water Pollution Prevention Plan ...... Page 15

Appendices

Appendix A :

Pre and Post-Developed Calculations for the Access Road and for

the Parking Lot and the Building ...... Page 17

Detention Storage Estimates and TargetPeak Outflow Rate ...... Page 35

Appendix B :

WQv and CPv Calculations for the Access Road and for the Parking Lot

& Building ...... Page 36

Introduction

SUNYIT Prevention Services proposes to develop a portion of a 20acre property in the Town of Marcy, Oneida County, New York.

The objective of this report is to provide all involved parties with information regarding the proposed stormwater conveyance system, drainage designs, and sediment/erosion control features for the proposed development.

Proposed Site Development Information

A vehicle maintenance facility for the SUNYIT campus is proposed. The site will be developed in general conformance with the Town of Marcy and Oneida County Zoning Ordinances. Approximately 2 acres of the 20acre parcel, owned by SUNYIT, will be developed at this time. The remaining portion will remain a brushy field with strands of woods to the south and west.

It is proposed that the driveway surfaces be constructed in accordance with the town’s current road design standards, which rely in part, upon the OneidaCounty and New York State DOT road standards.

Background Information

Pre-Developed Conditions

The property is currently undeveloped. The site is predominantly open meadows and brush with thick vegetation and stands of trees to the west and the south.

The property is part of SUNYIT’s campus and its north and west borders are Mulaney Road and Edic road, respectively.

In general, the pre-developed conditions are such that the parcel is divided into three drainage basins by existing ridges. However, one drainage basin concerns the developed site and will be used for calculations accordingly.

The ground surfaces north of the property are at a higher elevation than the building site. The slopes of the existing areas direct runoff to a wetland located south of the property. The water that flows off of these slopeshas an impact on the building site. The flows of water will be redirected away from the proposed building site via vegetated swales.

The ground surface of the portion of the property containing the building site falls to the south at slopes averaging around 3%, with minor increases and decreases in slope. Runoff flows via a combination of sheet and shallow concentrated flow into the wetlands located just south of the proposed development. Vegetated swales, at a 4/12 slope, go around the parking lot to the west and south, draining into the wetland. The wetland ultimately drains into an unnamed creek than runs through SUNYIT’s campus.

Post-Developed Conditions

In the post-developed condition, runoff will be collected by a network of grass-lined swales and culverts and directed into two separate stormwater management systems before being released into the wetland south of the property. This is consistent with pre-developed conditions.

Stormwater management systems for the building site will be designed so that peak post-development runoff rates do not exceed the peak pre-development runoff rates at any off-site discharge location. Stormwater management for the access road coming in to the building will be provided through the use of a dry swale. The dry swale will consist of a sediment forebay at the in-flow point which will collect and direct runoff into a dry swale as outlined in the New York State Department of Environmental Conservation’s (NYSDEC) Stormwater Management Design Manual. The sediment fore bays have been sized to contain 10% of the water quality volume (WQv). Discharge will ultimately be provided by a 4” perforated underdrain pipe. The outfall point of the dry swale has been configured to direct runoff into the existing wetland consistent with existing drainage patterns. A five foot wide easement will be needed in order to allow the underdrain pipe to daylight at an existing elevation.

Stormwater management for the parking lot and the building will be provided through the use of a micropool extended detention pond. The detention pond design also conforms to the (NYSDEC) Stormwater Management Design Manual.The pond will consist of a sediment forebay at the inflow point which will collect and direct runoff into a micropool. Discharge will ultimately be provided by a pre-cast concrete control structure. The outfall point of the basin has been configured to direct runoff into the existing wetland consistent with existing drainage patterns.

All site work shall be completed under the National Pollutant Discharge Elimination System (NPDES) general permit (GP-02-01) for construction activities, which is administered by the NYSDEC.

Comparison Of Pre-Development And Post-Development Runoff Conditions

Methodology

In accordance with the NYSDEC’s NYS Stormwater Management Design Manual, the present hydrology was compared to that of the developed conditions. This was accomplished by using a computer stormwater modeling program produced by Haestad Methods, Inc. known as PondPack. The peak discharge from both conditions was calculated using this software in conjunction with site-specific input. The Pond Pack program is based on the calculation procedures from the United States Department of Agriculture’s (USDA’s) TR-55,Urban Hydrology for Small Watersheds.

As part of this study, the Oneida County Soil Survey was also reviewed. The soil survey identified the majority if the soils on the property (~56%) as Kendaia (a) series. The Kendaia series consists of very deep, somewhat poorly drained soils formed in calcareous till. They are nearly level to sloping soils on footslopes and other moderately low areas on till plains. Saturated hydraulic conductivity is moderately high to high in the solum and moderately low to moderately high in the substratum. Slope ranges from 0 to 3 percent. The mean annual temperature is 49 degrees F. and means annual precipitation is 36 inches. Bedrock is more than 60 inches below the soil surface and in most pedons is deeper than 6 feet. The soil issomewhat poorly drained. The potential for surface runoff is high or very high. Saturated hydraulic conductivity is moderately high to high in the solum and moderately low to moderately high in the substratum.

Other Soils located on the property at lesser proportions include (~38.1%) Kendaia (b) series and (~5.7%) Lansing series. The Kendaia (b) series has the same properties as the Kendaia (a) series listed above except the (b) series has slope ranges from 3 to 8 percent.

The Lansing series consists of very deep, well drained soils formed in till. They are nearly level to rolling and steep soils on till plains. Saturated hydraulic conductivity is moderately high or high within the mineral solum, but moderately low or moderately high in the substratum. Slope ranges from 0 to 60 percent. Mean annual temperature is 48 degrees F. and mean annual precipitation is 38 inches.The soil is derived from shale, limestone, fine grained sandstone and siltstone. Mean annual precipitation ranges from 30 to 45 inches and the mean frost-free season ranges from 110 to 180 days. Elevation ranges from 400 to 1800 feet above sea level. The soil is well drained, internal drainage is slow or very slow, and the potential for surface runoff is very low to high.

The hydrostatic soil group (HSG) for Kendaia series soil is D and Lansing series is A. the soil grouping is a ranking of soil types from A to D, with A having a lower potential for generating storm water runoff and a higher infiltration rate, and conversely D having a higher runoff potential and lower infiltration rate.

Water Quality

To meet the pollutant removal goals as required by NYSDEC, approximately 60% of the WQv will be retained in the system between the micropool, dry swale, and the sediment forebays. The balance of the WQv will be released via a 30” deep permeable soil layerfor the dry swale and a low-flow orifice for the detention pond over a 24-hour duration.

Refer to Appendix B of this report for a summary of the WQv calculations.

Channel Protection

To meet the channel protection requirements, the channel protection volume (CPV), or volume of the 1-year storm event, will be detained in the system and discharged over 24 hours through a 30” deep permeable soil layer for the dry swale and a low-flow orifice for the detention pond.

Refer to Appendix B of this report for a summary of the CPv calculations.

Peak Discharge Calculation Summary

The following is a summary of the peak discharge calculations for a comparison of the present conditions with the developed conditions:

Summary of Discharge:

Access Road / Present / Developed
Area – Total (acres) / 0.64 / 0.64
Pervious / 0.64 / 0
Impervious / 0 / 0.64
Curve Number / 70 / 98
Time of Concentration (hours) / .60 / .14
Runoff (inches)
2-year/24-hour / 0.56 / 2.60
10-year/24-hour / 1.30 / 4.40
100-year/24-hour / 2.31 / 5.20
Peak Discharge (cfs)
2-year/24-hour / 0.21 / 2.22
10-year/24-hour / 0.59 / 3.96
100-year/24-hour / 1.09 / 4.80
Parking lot & Building / Present / Developed
Area – Total (acres) / 0.90 / 0.90
Pervious / 0.90 / 0
Impervious / 0 / 0.90
Curve Number / 70 / 98
Time of Concentration (hours) / .52 / .10
Runoff (inches)
2-year/24-hour / 0.56 / 2.60
10-year/24-hour / 1.30 / 4.40
100-year/24-hour / 2.31 / 5.20
Peak Discharge (cfs)
2-year/24-hour / 0.30 / 3.46
10-year/24-hour / 0.82 / 6.16
100-year/24-hour / 1.52 / 7.46

,Refer to Appendix A & B at the end of this report for additional information.

Storm Water Management System

The stormwater management system is designed to provide a maximum of a 24-hour extended detention of the WQv and the CPv. Stormwater runoff will be collected and directed into the proposed dry swale located south of the proposed access road and into the proposed detention pond located south of the proposed parking lot and building.

Stormwater runoff from the access roadway will be collected and directed (by catch basins) to the stormwater management area at the location described above.A 4” perforated underdrain pipe will release stormwater into the wetland consistent with existing drainage patterns.

Stormwater runoff from the parking lot and building will be collected and directed (by catch basins) to the stormwater management area at the location described above. A low-flow orifice will release stormwater into the wetland consistent with existing drainage patterns.

The stormwater management systems have been designed to satisfy both environmental quality and runoff quantity concerns. The systems shall be constructed, operated, and maintained in accordance with the NYSDEC requirements.

Stormwater Management

The dry swale, with 2:1 (H:V) side slopes, will be located just south of the proposed access road. The basin will contain a storage volume of 0.06acre-feet. The discharge control for the dry swale will be handled by a 30” permeable soil layer over filter fabric, a 6” layer of gravel and a 4” perforated underdrain pipe. This will beused to maintain CPv over a 24-hour period and to discharge the WQv over a 24 hour period. The 4” perforated underdrain pipe will direct stormwater from the pond to the existing wetland south of the southern property boundary.

The open channel dry swale is designed to hold the 10-year storm with six inches of freeboard. The bottom width of the dry swale is designed at 8’ to avoid potential problems, such as gullying and channel braiding.

The micropool extended detention pond will extend from elevation 628 to 632 with 2:1 (H:V) side slopes and will be located just south of the proposed parking lot and building. The pond will contain a total storage volume of .396 acre-feet to meet the target peak outflow rate. The discharge control for the pond will be handled by a 4-foot square concrete control structure containing a 2.5-foot wide rectangular weir. The weir crest will be set at an elevation of 631 to discharge the remaining storm events at flows not exceeding the pre-developed rates. A 4-inch diameter low-flow orifice with an invert elevation of 628.4 will be provided to maintain CPv over a 24-hour period. A 4-inch diameter low-flow orifice with an invert elevation of 628 will be provided to maintain the permanent pool elevation and to discharge the WQv over a 24-hour period. A 30-inch diameter HDPE pipe will direct stormwater from the pond to the existing wetland south of the property boundary.

The 100-year storm will reach an elevation of 632 in the basin. An emergency spillway channel will be provided on the southwest corner of the pond at elevation 633. The spillway will be routed into the existing wetland consistent with existing conditions.

The system shall be constructed, operated, and maintained in accordance with the NYSDEC requirements. Discharge from the fully developed site will not exceed the pre-existing conditions, as presented in this report.

Erosion & Sediment Control Requirements

The erosion and sediment control plan has been developed for the construction activities associated with the proposed project. Both temporary and permanent erosion and sediment control devices will be utilized to reduce the erosion potential from construction and ultimate site use, to decrease water quality degradation and to protect downstream waterways. The means and methods provided in the erosion and sediment control plan are based upon the New York State DEC Storm Water Management Design Manual as summarized.

Temporary Erosion and Sediment Control Facilities

The locations and construction specifications for the following temporary erosion and sediment control devices are shown on the erosion and sediment control plan and details:

  • Silt Fence: Silt fencing will be placed between graded and undisturbed areas to prevent sediment from entering the undisturbed areas.
  • Sediment Traps: Sediment traps will be installed in the proposed swales to reduce erosion in the swale by decreasing the velocity of flow during construction and allowing sediment to settle out.

Permanent Erosion and Sediment Control Facilities

  • Inlet/Outlet Protection: Stone fill aprons will be located at the culvert inlets and outlets as shown on the site plan to minimize scour and erosion.
  • Grass-Lined Diversion Swales: Swales will be constructed at various locations to collect and direct surface water towards the detention basin.
  • Surface Stabilization: Stabilization will be accomplished with vegetation and mulch, as indicated in the landscaping specifications.

As required by the NYSDEC, prior to any construction activities Fall 2006 Capstone will file a Notice of Intent (NOI) SPDES General Permit GP-02-01.

Construction Schedule and Sequence

Construction of the project is expected to begin in the summer of 2007. The general site notes and anticipated construction sequence for the site improvements consist of the following:

General Notes

  1. One (1) week prior to beginning earthwork operations, a pre-construction meeting will be held to discuss the erosion and sediment control plan and to finalize the paperwork for the Stormwater Pollution Prevention Plan, as specified in the DEC State Pollutant Discharge Elimination System (SPDES) General Permit for Stormwater Discharge from Construction Activities.
  2. Erosion and sediment control measures shall be provided prior to beginning any land disturbance activities. The devices providing protection to a given area shall not be removed until the disturbed lands in that area are stabilized.
  3. No disturbed area shall remain exposed for more than 14 calendar days, except for portions of the site in which work will be continuous beyond 14 days (i.e. the building footprint). Temporary vegetation, in accordance with DEC guidelines, shall be provided in all areas where construction activities have ceased for greater than 14 calendar days.
  4. During construction, the sediment and erosion control measures shall be inspected on a weekly basis by a DEC approved inspector.
  5. All sediment and erosion control measures shall be inspected every seven (7) days and immediately following rainfall events of greater than ½ -inch. The Owner (Developer) will be responsible to ensure that these required inspections are adequately performed.

Construction Sequence

  1. Construct stabilized construction entrance for access to/from the construction site.
  2. Install silt fences as indicated.
  3. Seed and mulch diversion swales. Provide anchoring on slopes exceeding 3:1 to protect seed and mulch.
  4. Note that all swales are to be seeded and mulched for vegetative cover immediately after grading. Refer to the applicable details for specifics on seeding and mulching for temporary devices.
  5. Strip and stockpile topsoil. Cover stockpile and provide silt fencing or straw bale dikes around perimeter of staged topsoil and/or temporarily staged piles of fill.
  6. Begin earthwork and grading operations.
  7. Place fill material to the limits indicated.
  8. During grading operations, install and maintain all erosion and sediment control devices.
  9. Install utilities. The contractor shall protect all utilities from sediment infiltration.
  10. Remove temporary erosion control devices once vegetation has been established and/or construction is completed.

Inspection Procedures and Maintenance