Eastwick Flood Risk Management Study

The Eastwick study area is in southwest  Philadelphia along the confluence of Darby and Cobbs Creeks, west of the Schuylkill River, and north of the Delaware River and Philadelphia International Airport. Eastwick is primarily composed of residential and commercial establishments while the adjacent area to the south and east is explicitly comprised of industrial and commercial establishments. Eastwick is experiencing increases in the frequency, duration, and intensity of riverine and marsh flooding during storm events including hurricanes and major nor'easters.

The authority for this project is Section 205 of the Flood Control Act of 1948 (Public Law 80-858), as amended. Under this authority, the U.S. Army Corps of Engineers is authorized to plan, design, and construct small flood risk management projects. Each project is limited to a Federal cost of not more than $10 million, including all project related costs for feasibility studies, planning, engineering, design, and construction. The feasibility study will evaluate an array of alternatives to reduce flood risk in the area.

A U.S. Army Corps of Engineers feasibility study involves assessing problems and opportunities related to water resources issues, coming up with alternative solutions to address those problems, comparing those solutions and, ultimately developing a recommendation. Some studies result in a "no federal action" recommendation. Others result in a recommendation for implementation.

Throughout the study, the team conducts environmental, economic, and engineering analyses to compare alternatives. The Army Corps compares the cost to implement specific alternatives with the benefits (in the case of flood risk management, this means reduced flood damages) if the alternative is implemented. Additionally, the team evaluates if the alternatives are technically feasible from an engineering, environmental, and social standpoint. The final product, a feasibility study report, presents science-based decisions and the reasons that led to those decisions.

The U.S. Army Corps of Engineers signed a Feasibility Cost Sharing Agreement with the Philadelphia Water Department in May of 2019. Much of the study work conducted to date includes documenting existing conditions and flooding-related problems, and consideration of various flood risk management measures. Several measures have been ruled out including structure elevation and floodwalls due to various technical reasons. The following measures/alternatives are still under consideration: 

  • Levee: the study team is evaluating different alignments for a potential levee and conducting economic, hydraulic, and engineering analyses to determine if a levee is feasible.  Several challenges associated with the levee alternative include the possibility of increasing flooding in nearby areas and the proximity of the Lower Darby Creek Area Superfund Site managed by the EPA. The levee currently appears to be the best option under consideration, but USACE is still conducting additional analyses.   
  • Structure acquisition/buyout is also still under consideration. It would involve the purchase of some properties that are deemed high risk, or suffered repetitive loss from previous storms, with the land reverting to open space. Acquisition would need to be carried out by the City of Philadelphia as the non-Federal sponsor of the project. 

Next steps for the study include conducting economic, engineering, and environmental analyses to compare and evaluate the alternatives. The study team estimates identifying a Tentatively Selected Plan in 2023.  This will be followed by the release of a draft report and a formal public comment period. 

Several related efforts conducted by the Philadelphia Water Department and USACE have informed and led to the current ongoing study: 

  • Based on historical floods and in direct response to flooding caused by Tropical Storm Lee on September 7, 2011, Philadelphia Water Department (PWD) sent a questionnaire to Eastwick residents requesting information such as source and depth of flooding. This survey was also made available to the public. Based on the responses, PWD developed a geospatial shapefile with attribute data about the properties affected from September 1999 to September 2011. 
  • In December 2014, USACE completed the Eastwick Stream Modeling and Technical Evaluation report.  The study was conducted under the USACE Planning Assistance to States program.  The purpose of the study was to preliminarily evaluate whether a levee would provide flood risk management for the Eastwick neighborhood during extreme rainfall events without adversely impacting other properties and residents along Darby and Cobbs Creeks. This study was preliminary in nature and involved various assumptions. The final report recommended to City of Philadelphia that additional study may be warranted. 
  • In September 2016, USACE completed the Darby and Cobbs Watersheds Hydrologic Study.  The purpose of the investigation was to determine more accurate flow-frequency relationships in the lower Darby-Cobbs watershed in the vicinity of southwest Philadelphia, PA.  Recent studies, including the Eastwick Stream Modeling and Technical Evaluation described above, had revealed that the hydrologic information for the area was outdated, stream gage information may be inaccurate, and supporting data was lacking.  The study reviewed existing flow-frequency estimates in the watershed, investigated discrepancies between the existing estimates, and suggested other methods to provide the best estimates for use in related studies.

A levee is an earthen (soil) embankment built to keep water from a creek or river from flowing out of its bank and flooding a given area. It does not eliminate flooding from all sources. 

Submit Comments

Comments are accepted on an ongoing basis throughout the study process. Additionally, there will be a specific comment period after the release of the draft report. 

By email: PDPA-NAP@usace.army.mil