13 2026 02 12 Crestmont CC Stormwater O and M Manual

The bioretention basins are designed to store and percolate the volume of stormwater generated by the water quality design storm event, which is defined as 1.25 inches of rainfall over a period of 2 hours. For each basin, the first outlet opening within the outlet control is set a maximum 12” above the bottom of the storage area of the basin in order to promote infiltration through the soil media layer and achieve 80% or 90% TSS removal. 4.1.2 Porous Pavement Systems There is 1 porous pavement systems proposed on the project site. Porous pavement systems consist of a porous asphalt surface layer, a choker course that filters pollutants, subbase aggregate that acts as the stormwater runoff storage component of the BMP, and an underdrain collection system comprised of perforated 4” diameter HDPE pipes encased by stone aggregate both above and below the collection system piping. The depth of the subbase aggregate has been designed to store the volume of stormwater generated by the water quality design storm event in order to achieve 80% TSS removal credit. The underdrain collection system prevents runoff from infiltrating into the native subsoils; instead, the runoff is captured and discharged into the proposed subsurface conveyance network. 4.2 Stormwater Conveyance Network The proposed project utilizes various series of subsurface conveyance networks to facilitate the collection and conveyance of stormwater runoff for the 25-year design storm event. The conveyance networks consist of precast concrete inlet structures, precast concreate manhole structures, drainage piping, and riprap aprons. Refer to Drawings CG103 and CG104 – Partial Drainage Plans – for an overview of the conveyance network and location of various pipes and structures. 4.2.1 Storm Sewer Conveyance Piping High Density Polyethylene (HDPE) Pipe is proposed for the conveyance of stormwater where the proposed cover over the top of the pipe is a minimum 2 feet. Class V reinforced concrete pipe (RCP) is proposed within the right-of-way. Perforated HDPE pipe is proposed to be utilized as the underdrain collection system piping for the BMPs specified to utilize an underdrain collection system as part of their design. An HDPE flared-end section is proposed in bioretention basin SSBB-2. 4.2.2 Precast Concrete Structures Precast concrete inlets utilized throughout the site generally consist of

part of their design. An HDPE flared-end section is proposed in bioretention basin SSBB-2. 4.2.2 Precast Concrete Structures Precast concrete inlets utilized throughout the site generally consist of NJDOT Type A, Type B, and Type E inlets. Type B curb inlets will be fitted with Type N Eco curb pieces to prevent trash and floatables from entering the conveyance network. All inlet grates shall be bicycle-safe, and 4