E Mt Airy – Germantown Flash Flooding & Rezoning

Northwest Philadelphia’s Wingohocking Sewershed (maps below) is in a serious catch-22 situation because the historic Wingohocking Creek was enclosed into the City’s combined sewers many years ago. Key points:

  • Numerous areas in the Wingohocking are prone to both surface flash flooding and sewer backups from stormwater.
  • There are no designated 50-100 year flood plains because the historic Wingohocking Creek was enclosed in a sewer and FEMA does not consider sewer overflows in flood plain designations.
  • Wingohocking Sewershed homeowners are not eligible for FEMA supported flood insurance even though they may live in flood prone areas.
  • The City has allowed impervious cover in the Wingohocking Sewershed greater than the City’s combined sewers can handle during some flash flooding conditions.
  • Downstream flooding in the City’s combined sewers is caused by upstream stormwater flows greater than the capacity of the downstream combined sewers.
  • Upstream Wingohocking impervious cover contributes to downstream flooding.

The City has a dual role in the E Mt Airy – Germantown flooding situation:

  1. Manage impervious cover to limit stormwater flows to available downstream capacity
  2. Provide adequate combined sewer capacity to protect life and property.

In the Wissahickon Watershed, the City has a Watershed Overlay District that restricts impervious cover to 10 – 45% based on land category. There is no comparable Wingohocking Sewershed Overlay district.  Properties along Germantown Ave between Cresheim Road and Allen Lane have an impervious cover limit while properties from Allen Lane to Washington Lane in the Wingohocking Sewershed have no impervious cover limit.

Wingohocking flooding in September, 2011 caused the drowning death of a young woman who was trapped in her car in 6-feet of flood water near Belfield and Haines( video here). After initial modeling efforts by Water Department and US Army Corp of Engineers, the Water Department issued a Request for Proposals in the fall in 2015, hired a highly regarded engineering firm and received their draft report in the fall of 2018. We are awaiting the release of this critical report.

The City Planning Commission reports that Germantown Avenue is experiencing “rapid redevelopment today”. This argues for immediate zoning controls of impervious cover in the Wingohocking Sewershed, including properties along Germantown Ave.

The Philadelphia City Planning Commission will be holding a Germantown Avenue Rezoning meeting on March 27th. Please contact EMAN, Mt Airy USA, Mt Airy BID and the Planning Commission to ask that the Philadelphia Water Department attend the March 27th meeting and provide information on the Germantown Storm Flood Relief Capital Improvement Plan and address the potential impacts of rezoning Germantown Ave., a new Wingohocking Sewershed Overlay District or other steps they recommend to reduce today’s Wingohocking flooding situation.

We must begin taking steps to protect life and property in the Wingohocking Sewershed.

FloodingGuide_Germantown_Page_12Wingohocking_Simple_MapFlash_flooding_2035_Plan

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