Historically, many large dams in the United States have been built to prevent or reduce flood damage. These structures protect downstream communities from severe storm events by a controlled storing (impounding) and release of flow. New England has numerous large flood control dams, many built by the U.S. Army Corps of Engineers (USACE) from the 1930s through early 1970s. USACE reservoirs have prevented millions of dollars in flood damage, provided recreational opportunities, and protected over 60,000 acres of wildlife habitat. But what happens to these dam structures when age, deficiencies, or seepage threaten the structural (and flood control) integrity or pose a risk of dam failure?

USACE reservoirs have prevented millions of dollars in flood damage, provide recreational opportunities, and protect over 60,000 acres of wildlife habitat.

When many people think of a potential dam failure, their thoughts conjure up Hollywood images of mighty concrete structures bursting and releasing torrents of water upon a sleepy unsuspecting village downstream. In reality, the dam failure process is rarely so instantaneous – rather, cumulative deficiencies and changes in the dam structure build up over time. Regular inspections of dams look for tell-tale indications of these deficiencies and seepage, such as piping, boils, and internal erosion problems. When encountering these problems, engineers evaluate the risk of dam failure and, if necessary, develop measures to rehabilitate structural defects. The environmental impacts of major dam repair projects can be considerable and must be evaluated under National Environmental Policy Act regulations.

For the USACE, the Battelle team has conducted several projects that assessed environmental impacts to natural, socioeconomic, and cultural resources as a result of dam rehabilitation in the New England area. All of these facilities had been experiencing seepage problems that posed unacceptable risk of dam failure. For each of these projects the team produced an Environmental Assessment and a detailed assessment of the environmental impacts of dam failure.

The team of engineers, ecologists, biologists, and other scientists provided the technical analysis necessary and evaluation of potential impacts of rehabilitation alternatives in regards to wildlife, vegetation, other biota, natural and cultural resources, such as community impacts and recreation concerns. Coordination with regulatory agencies and production of public hearing materials and meetings with stakeholders and state and federal officials during site visits allowed the team to evaluate as wide a range of issues as possible. For the dam failure damage assessment, the team determined qualitative and quantitative impacts of catastrophic project failure on the site and downstream areas. Applying GIS and other tools allowed examination of the extent and magnitude of these impacts upon wildlife, vegetation, and other natural and human resources at the project area. Additionally, these assessments were used to estimate duration of recovery periods and to propose potential remediation approaches. As part of report preparation, the team provided recommendations on measures to minimize adverse environmental effects before, during, and after construction.

The results of these comprehensive analyses allow the USACE to ensure that any dam rehabilitation solution not only solves the technical and engineering problems, but also considers and mitigates ancillary impacts to the natural, cultural, and socioeconomic environment.

For more information, please contact Karen Foster at (781) 952-5370 or via e-mail at foster@battelle.org.