Manayunk Sewer Basin Project: Innovative Green Design

Client:: Philadelphia Water Department

Location:: Philadelphia, PA

The Philadelphia Water Department was required by the state of Pennsylvania to eliminate a Combined Sewer Overflow into the Schuylkill River. PWD retained Hazen and Sawyer to design a 3-million gallon CSO detention facility on Venice Island, in the vicinity of a recreational facility, historic barge canal, and business district – a sensitive area requiring careful consideration of neighborhood impacts.

Project Outcomes and Benefits

LEED-silver eligible building with numerous energy-saving and other sustainable design measures, featuring a “living” roof system, wetland rain garden, water conservation measures, and maximized use of recycled materials; architectural features blend into surrounding park area.
Location on tight site between the river and the railroad that serves industry adjacent to the Manayunk Canal.
Performed extensive modeling of 11,452-acre drainage area using 50+ years of rainfall data to develop the conceptual design and ensure long-term effectiveness of the facility.
Facility will eliminate adverse impacts on water quality in the Schuylkill River that result from CSO discharge.

Rendering of the Manayunk CSO Detenion facility
Hazen and Sawyer designed the Manayunk CSO Detention building with a swooping greenroof that blends well with the surrounding area parkland. The facility contains many environmentally-friendly features and is LEED Silver-eligible.

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The Manayunk CSO Detention Facility will be constructed on a tight site on Venice Island, adjacent to parkland, railroad canal, and business center. The detention tanks will be constructed underground, with plantings restored atop the tanks.

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Rendering of the Manayunk CSO Detenion facility
Hazen and Sawyer designed the Manayunk CSO Detention building with a swooping greenroof that blends well with the surrounding area parkland. The facility contains many environmentally-friendly features and is LEED Silver-eligible.
The Manayunk CSO Detention Facility will be constructed on a tight site on Venice Island, adjacent to parkland, railroad canal, and business center. The detention tanks will be constructed underground, with plantings restored atop the tanks.

Hazen and Sawyer has designed an innovative, LEED-silver-eligible structure to house the Manayunk CSO Detention facilities, comprised primarily of a concrete basing that will receive flows by gravity when the area’s interceptor becomes surcharged (causing backup) during storm events. The facility will pump flows back to the sewer system when the storm event has subsided and the interceptor has sufficient capacity to convey these flows to the sewage treatment plant. It is expected that flows will be diverted to the new facility about six or seven times per year. Hazen and Sawyer utilized state-of-the-art InfoWorks modeling software, converting PWD’s prior (EPA-SWMM) model to analyze hydraulics and design the detention chamber as well as inlet and outlet structures.

Our design incorporates the use of many “green” features, including drought-resistant roof plantings; rainwater collection for a wetland garden in the front of the facility; regionally-harvested stone for the building façade; a glass stair tower to allow light to entire all sides of the building and reduce the need for interior lighting; photo- and occupancy sensors for energy efficiency; shade and reflection devices for sun control, to reduce the need for air conditioning; and water-conserving plumbing fixtures.

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