2nd & Erie Stormwater Retrofit Design-Build

The intent of the stormwater management system was to reduce and/or regulate the stormwater runoff through a slow release detention system and manage the first 1.5” of rainfall at a maximum release rate of 0.05 cfs/IA acre.

The design solution involved construction of an underground stormwater retention facility to be placed beneath the existing asphalt parking lot of the facility. The underground basin utilized precast Terre Box Stormwater system having three (3) rows at 266’+/- and (4) rows at 189’+/- for a total storage volume of 123,796cf and 266 pieces.

CEG prepared an Existing Resource and Site Analysis (ERSA) Application and obtained permit approvals from the Philadelphia Water Department (PWD) for the installation of a precast Terre Box Stormwater system located below ground at the vacant warehouse facility. The underground storage system was designed to capture and slow release the 1 ½” storm event at a maximum release rate of 0.05 cfs/IA acre and qualified for PWD stormwater retrofit credits.

CEG designed the retrofit stormwater management practice, obtained City stormwater approvals, prepared probable cost estimates, and coordinated with various project stakeholders including the project owner, project manager, geotechnical engineers, PWD staff, and PADEP staff.

Stormwater Management Design included conceptual and final design, preparation of plan documents to illustrate drainage areas and design layout and details. Additionally, a Stormwater Report was prepared to describe methodology, calculations, and associated worksheets and attachments.

Construction work involved limited demolition of existing asphalt and removal of overburden where the underground stormwater management facility was being installed, the installation of HDPE, concrete, PVC, cast iron, and ductile iron storm sewer structures – pipes manholes, cleanouts, inlets, the underground detention basin, outlet structure, domestic and fire water mains, as well as paving restoration of the trenched areas with asphalt.

CEG also provided geotechnical and environmental services for disposal of clean and contaminated excavated soils.