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HomeMy WebLinkAbout5 Project NarrativeStormwater Calculations 1272, 1276 & 1282 Route 28 South Yarmouth, MA 02664 3 PROJECT NARRATIVE The property comprises three lots, 1272 Route 28 which has a small commercial building and measures 11,936 SF, 1276 Route 28 which has 5 cottages and measures 21,780 SF and 1282 Route 28 which has a gas station and measures 16,117 SF). The area of the combined lots is approximately 49,833 square feet (1.14 acres). All properties are located in the B-2 Business District. It is bound to the north by residential properties, to the south by Route 28 and to the east and west by existing commercial businesses. Currently there are seven buildings on the property, an 820 square-foot steel canopy over two dispensing pumps, an 1,800 square foot convenience store and 5 residential cottages with associated paved parking. Access to the site is via four existing driveways from Route 28. Currently most of the site runoff drains to Route 28 without any treatment (refer to Existing Conditions Plan). The canopy structure as well as some of the cottages are existing non-conforming structures and do not meet the current required front and rear setbacks. Existing canopy is 2 feet from the front property line where 30 feet is required and some cottages are 10 feet from the rear property line where 20 feet is required. In addition, the property does not meet the required 20-foot front and rear landscape setbacks. Most of the front landscape setback is completely covered with impervious surfaces and driveways and there are some undefined landscape within the rear 20- foot landscape buffer. The owner of the properties would like to redevelop the property and demolish all existing buildings on site and construct a gasoline filling station with four fueling dispensers, overhead steel canopy, two double walled fiberglass fuel storage tanks and a 3,890 square-foot building with convenience store and a drive thru and a separate two-story building with 4 residential units (total of 3,755 SF) along the southeast corner of the property. The proposed canopy would be placed 41 feet from the front property line (existing is 2 feet) and proposed building would be 47 feet in compliance with the 20-foot rear setback (existing is 10 Stormwater Calculations 1272, 1276 & 1282 Route 28 South Yarmouth, MA 02664 4 feet). Site improvements would also include a new stormwater collection system, new septic system, new utilities, landscape, and lighting. The new building design including drainage, utilities and landscape improvements to the site are substantially more attractive and architecturally pleasing than the existing one and would enhance the neighborhood. Presently all runoff generated from impervious and developed areas on site sheet flows untreated in a southerly and northwesterly directions and drains to Route 28 storm drain collection system and to adjacent properties to the north and west. With the proposed site improvements all runoff generated from paved surfaces, landscaped and roof areas will be collected by a closed drainage system, treated, and discharged to an on-site infiltration system designed to accommodate the 100-year storm in compliance with the MASSDEP and the Town of Yarmouth stormwater regulations. Runoff from site to adjacent properties and to Route 28 will be eliminated as a result of the site redevelopment. The project includes provisions that will provide infiltration/groundwater recharge. Stormwater runoff from the project parking areas will be collected by a Precast Concrete Stormceptor Unit and deep sump catch basin then directed to the subsurface infiltration systems designed to completely infiltrate stormwater runoff generated from a 100-year Type III storm event. Stormwater runoff generated from roof surfaces will be collected by a closed pipe conveyance system and also directed to a subsurface infiltration facility designed to completely infiltrate stormwater runoff generated from a 100-year Type III storm event. The subsurface infiltration facility will provide recharge to groundwater, improve water quality, and provide attenuation of peak flows. This design consideration will ensure that the maximum recharge will occur. A new septic system in compliance with MASSDEP Title V would be constructed on site. Access will be improved by reducing curb openings and providing additional landscape buffer within the front landscape setback an increase of approximately 80% over existing conditions. Stormwater Calculations 1272, 1276 & 1282 Route 28 South Yarmouth, MA 02664 5 An erosion barrier consisting of staked silt sock with a siltation fence will be placed around the entire proposed limits of construction as shown on the site preparation and demolition plan prior to construction. In addition, a tracking gravel pad will be installed prior to construction at the site for dust control. The contractor will be responsible for maintaining the erosion barrier and gravel pad during the entire construction period. Erosion control devices will be removed after construction is completed and all disturbed areas are restored to pre-existing conditions.