US Army Corps of Engineers
Philadelphia District & Marine Design Center

Study Process

 Planning Approach

The US Army Corps of Engineers (USACE) was given authority under the Water Resources Development Act (WRDA) of 1986 to conduct a two-phase study to evaluate and recommend appropriate flood risk management and ecosystem restoration projects for the Delaware River Basin. Separate authorization in 2005 underscored the need for these flooding issues to be addressed. The initial or reconnaissance phase of the study was completed in March 2003 at full Federal expense. The Corps and the New Jersey Department of Environmental Protection (NJDEP) then entered into an agreement to perform the second phase of the study, a cost-shared feasibility study for flood risk management projects. This study is an interim response to the legislative authority. The opportunity remains for other non-Federal entities to cost share with the Corps on additional interim studies in other portions of the Basin.

The Interim Feasibility Study for New Jersey may recommend alternative plans for the Corps and State of NJ to implement in a cost-shared partnership, and other plans or measures for implementation by the State or local communities. The study will result in a Draft Integrated Feasibility Report and Environmental Assessment (EA) or Environmental Impact Statement (EIS) which will meet the requirements of both the Corps’ Feasibility Study and the National Environmental Policy Act (NEPA).

The Integrated Feasibility Report will be reviewed by an independent team of Corps experts reviewed and then submitted to Corps Headquarters and the Environmental Protection Agency (EPA) in Washington, D.C.. After public review and comment, the proposed report of the Chief of Engineers and final EA or EIS will be sent to heads of Federal agencies and governors of affected states for comment. The Chief of Engineers report will then be transmitted to Congress and to the President's Office of Management and Budget (OMB), who comments on the report as it relates to the President's programs. Implementation of the project must then be authorized by Congress, normally as part of a Water Resources Development Act (Omnibus Bill). The Secretary of the Army and appropriate non-Federal sponsors will sign a formal Project Partnership Agreement (PPA) once Congress has appropriated funds for project implementation.

The feasibility study will follow a six-step process to solve problems. The approach and status of each step is described below:

1. Identify water resources problems in the study area. Numerous documents were reviewed to develop a clear understanding of the historical flooding and impacts. Additionally, site visits occurred with municipal representatives who were also solicited for their impressions of the impacts of recent flooding as well as for their views on possible flood risk management options. This information helped to focus data collection efforts to the areas of greatest need.

2. Collect data on the problems identified. The Corps is working with numerous agencies including the Delaware River Basin Commission (DRBC), NJDEP and the United States Geological Survey (USGS) to develop current models to accurately quantify current and future flood risks for the study area communities. The Federal Emergency Management Agency (FEMA), through its National Flood Insurance Program, identifies and maps the Nation’s floodplains through the use of hydraulic models. An update of Flood Hazard maps along the Delaware River is underway, and when complete, will represent the most accurate depiction of current flood hazards to date. To assess future flood risks, the collection and assessment of important hydrologic and hydraulic parameters such as land use, forest canopy, impervious areas where rainfall can not infiltrate the soil, reservoir characteristics and river valley surveys was undertaken. This data was used to calibrate a USGS flood-analysis model, and is in the process of being modified to model the impact of projected population growth, allowing for identification of possible future flood risks.

Data was also collected on the location, elevation, and type of structures within the communities in the Delaware River Basin. This structure inventory allows for an economic assessment of flood damages and of the ability of various flood risk management measures to reduce damages.

3. Develop alternatives to solve the problems. Taken as a whole, the plan formulation approach recognizes the need to balance flood risk management and ecosystem restoration opportunities with other social and environmental needs within the study area. In accordance with planning guidelines, among the alternatives measured is a “no action alternative”, defined by a forecast of conditions without any new flood risk management or ecosystem restoration projects. In addition to the without project condition, the broad range of alternatives include the following:

  1. Regional Flow and Flood Risk Management. While the Interim Feasibility Study for New Jersey is considering the full range of flood risk management measures that may be implemented within the study area portion of the State of New Jersey, other actions within the Delaware River Basin may alter the magnitude, frequency or impacts of flooding within communities throughout the Basin. These regional flood risk management measures include ongoing initiatives such as the Flexible Flow Management Program (FFMP), under which the states of Delaware, Pennsylvania, New York, and New Jersey agree to certain obligations and limitations concerning diversions and releases from reservoirs in an effort to manage water supply, ecological health, and the impacts of flooding in the Basin. The effects of these measures in reducing flood damages in the New Jersey study area, as well as potential reduction in flood risks in New York and Pennsylvania will be considered when evaluating alternatives. However, the Interim Feasibility Study is not evaluating FFMP itself or making recommendations for flow management.
  2. Ecosystem Restoration. Ecosystem restoration measures seek to restore the functional outputs of important habitats within the study area. Restoring wetlands may also provide localized flood risk management by slowing the speed of floodwaters, absorbing the force of flow, detaining floodwaters, and filtering out suspended solids. Through these actions, wetlands can lower flood heights and reduce the erosive potential of the water.
  3. Non-structural Measures. Non-structural measures move what is being damaged out of harm’s way, rather than attempting to alter the movement of water. Non-structural measures include a variety of techniques, including land-use controls to limit future development in the flood hazard areas, acquisition or relocation of flood-prone development, or retrofitting existing structures by raising the structure above the flood elevation, or other floodproofing approaches.
  4. Structural Measures. Structural measures consist of structures designed to control, divert, or exclude the flow of water from the flood-prone areas to the extent necessary to reduce damages to property, hazards to life or public health, and general economic losses. Structural measures can include increasing channel flow capacity, constructing levees and/or floodwalls, and incorporating backflow prevention structures such as flap valves and sluice gates within levees and floodwalls.

The approach to developing a comprehensive plan is to separately identify and evaluate the over-arching regional management measures, and more localized measures necessary to address specific problems or opportunities. The regional measures will be identified for possible implementation for the overall study area, either separately or in combination with other alternatives.

These measures include ecosystem restoration measures and individual structural and non-structural measures. These measures have been developed separately as features that can address the needs for ecosystem restoration and flood risk management. While structural and non-structural measures can address the need for flood risk management, ecosystem measures can possibly address both the need for ecosystem restoration as well as flood risk management. Once the evaluation of these features has been undertaken, the measures will be evaluated to identify features that are complementary and could be combined. This will most likely involve identifying the combination with the most cost-effective regional flood risk management alternatives, and the most cost-effective ecosystem restoration and community-specific structural and non-structural flood risk management alternatives. This process will use a systems approach to evaluate the effects of measures on the larger watershed in which they are located.

4. Evaluate the effects of the alternatives. This evaluation will consider potential performance, design, cost, institutional constraints, environmental constraints and potential impacts. The approach to evaluating alternatives involves four general tasks:

    1. Forecast the most likely with-project condition expected under each plan using the same critical variables included in the without-project condition.
    1. Compare each with-project condition to the without project condition and document the differences between the two.
    1. Characterize the beneficial and adverse effects by magnitude, location, timing and duration.
    1. Identify the plans that will be further considered in the planning process based on a comparison of the adverse and beneficial effects and the evaluation criteria.
      National Economic Development (NED), National Ecosystem Restoration (NER), Environmental Quality (EQ), Regional Economic Development (RED), and Other Social Effects (OSE) are evaluation criteria used by the Corps to evaluate and display the different effects of alternative plans.

5. Compare the alternatives. In this step, the alternative plans, including the no action plan, will be compared against each other. The comparison may require some tradeoffs between the different accounts. For example, a plan providing greater NED benefits may create fewer NER benefits. Tradeoffs will be documented to inform the plan recommendations.

6. Select a plan for recommendation. A selected alternative plan must be shown to be preferable to the other alternatives considered during the planning process, including the no action plan. A plan will be identified as a NED Plan, a NER Plan or a Combined NED/NER Plan, depending on the types of benefits the plan will produce. At the request of the NJDEP, a Locally Preferred Plan (LPP) may be identified that deviates from either the NED and/or NER Plan.