Specifications include, but are not limited to: The successful contractor shall provide all labor, materials and equipment to perform the work detailed on Sheets 4 and 5 of the site plan prepared by Stone Environmental, Inc, on November 2022 and entitled GRANLIDEN STORMWATER IMPROVEMENTS, TOWN OF SUNAPEE, NEW HAMPSHIRE. The Granliden Community Association (GCA) is a residential community sited on 150 acres adjacent to Lake Sunapee and consists of 108 townhouse units and six single-family homes. The GCA, in partnership with LSPA and Stone Environmental, has developed a plan to address stormwater runoff, erosion, and stabilization of their shorefront property to improve and protect the water quality of Lake Sunapee. The job consists of regrading, crowning and paving the beach access road and gravel parking area to redirect runoff into constructed stormwater control measures. The beach access road is currently paved. The job includes the construction and installation of stormwater control measures that include three vegetated swales, a level spreader, two sediment traps, a deep sump catch basin, an asphalt berm and a landscaping berm. Once completed, this project will prevent stormwater from eroding the gravel parking area and beach area and transporting sand and debris into Lake Sunapee. The contractor must provide costs for all items within the project, as described below and as shown on the Plan or in specifications. Road & Parking Area Regrading, Crowning and Paving: The contractor will regrade, crown and pave the access road and parking area (about 15,670 ft2) to redirect runoff into stormwater control measures matching contours shown on sheet 4 and following the typical roadway detail shown on sheet 5 of the plan. Contractor will be responsible for the removal and/or supply of road materials as needed to complete task. Vegetated Swales & Level Spreader: The contractor will excavate necessary materials to construct two vegetated swales with a combined length of about 282 linear feet using topsoil as shown and specified on sheet 4 and 5 of the plan. The contractor will hydroseed swales using a soil binder and New England conservation seed mix. The level spreader will be a minimum of 6 inches wide, span the length of the swale (6-8 feet), and be made of steel, concrete, or granite. Vegetated Swale with Underdrain: The contractor will excavate necessary materials to construct a 150 linear foot vegetated swale with underdrain using a 6” perforated PVC pipe, 1 and 2 inch double washed crushed stone, earthen fill, and topsoil as shown and specified on sheet 4 and 5 of the plan. The contractor will hydroseed swales using a soil binder and New England conservation seed mix. Sediment Traps: The contractor will excavate necessary materials to create two sediments traps using crusher run gravel bedding and riprap as shown and specified on sheet 4 and 5 of the plan. Deep Catch Basin and Outlet Pipe: As shown and specified on page 4 and 5 of the plan, the contractor will: • Remove existing drop inlet stormwater structure and replace it with a deep sump catch basin approximately four feet wide and 6 ½ feet in depth reconnecting existing inlet and outlet pipes using rubber boots at connections. • Reset, clean and shorten the existing 18” HDPE pipe outlet by 3-4 feet during catch basin installation. • Install a headwall structure and stone spillway at the outlet of the 18” HDPE pipe. Asphalt Berm: The contractor will construct a 1-foot-high by 3-foot-wide asphalt berm approximately 55 feet long at base of parking area to regulate flow to beach area. Paved area behind berm must be sloped towards catch basin as shown and specified on page 4 and 5 of the plan.
