For the 2nd Friday in July, there was flooding in the historic Wingohocking Creek Watershed, this time at E Mt Pleasant Ave and Sprague St. The previous July 2020 flood occured at Belfield and Church on July 10th (link).
Here is a short video that shows the flooding between the SEPTA bridge and Devon St.
This flooding was caused by the blocked stormwater inlet shown in this picture.
The July 11th Belfield and Church flooding (link), on the other hand, was caused by too much stormwater runoff overwhelming the sewers in that area.
The July 24 rainfall for Philadelphia is shown in this map which shows that our area got 1.5 – 2 inches and parts of Germantown got 2.5 – 3 inches.
As our global climate warms, we are seeing more intense rain storms. The July 10 and July 24 storms are an example of what we can expect. Please let me know if you see historic Wingohocking Watershed flooded intersections, railroad underpasses of other flooding so that we can log and document them to make sure that the City is aware and taking steps to both clear our inlets and increase our combined sewer capacity to reduce future flooding.
If you live near on of PWD’s 24 flood prone intersections (link) please be sure to get homeowners – renters insurance.
Tropical Storm Fay (link1, link2) passed through Philadelphia on July 10, 2020. This storm dumped 2 – 4 inches of rain on the Philadelphia area from about 8:00 AM to 4:00 PM on Friday, July 10th.
This plot shows NOAA’s Advanced Hydrologic Prediction Centers (AHPC) precipitation map for Philadelphia as of 8:AM on July 11, 2020.
The map shows the historic Wingohocking Creek Watershed which covers a major portion of NW Philadelphia. You can see that the Wingohocking Watershed received anywhere from 2.5 to 4 inches of rain over this storm.
This storm caused significant flooding at Belfield and Church. A local resident captured the video of the flooded intersection and posted it on Facebook at this link.
The Philadelphia Water Department has released an executive summary (link) of their multi-year study of stormwater flooding in Germantown – E Mt Airy. Their findings provide a wake-up call on flash flooding risks in this highly developed part of Northwest Philadelphia.
The combined sewers that the City built in the late 1800s and early 1900s to enclose the Historic Wingohocking Creek are simply too small for today’s stormwater runoff, causing sewer backups in nearly 2,800 homes and local flooding in the 24 intersections highlighted in this map.
PWD estimates flood annual flood damages of $7.1 millions to buildings and $1.6 million to vehicles.
PWD conducted detailed investigations into 2 storm relief options: 1) stormwater storage, and 2) tunnel relief. Both options are shown in the Executive Summary, however they are difficult to read. The map below reproduces the Water Department’s Storage Option.
Do you live in a flash flood prone area in Germantown – E Mt airy? If you do, your 1st priority should be to obtain flood insurance. Your 2nd step should be to ask your local elected officials, PWD, and your local community groups what steps they are taking to inform the public about our flash flooding problems and steps to reduce the risk.
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:
Manage impervious cover to limit stormwater flows to available downstream capacity
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.