Accession Number:

AD1081525

Title:

Rock Demolition and Hazardous Debris Removal for Ecosystem Restoration on the Elwha River

Descriptive Note:

Technical Report

Corporate Author:

ERDC VICKSBURG United States

Report Date:

2019-05-01

Pagination or Media Count:

70.0

Abstract:

The Elwha River is a unique river system located on Washingtons Olympic Peninsula and was dammed in the early 20th century for hydroelectric power. Approximately one century later, these dams, the Elwha Dam and Glines Canyon Dam, were removed to restore the rivers natural ecosystem. In 2015, the National Park Service NPS engaged with the U.S. Army Engineer Research and Development Center ERDC to provide subject matter expert support to the final stages of the restoration project. In September 2016, ERDC conducted a project for removal of hazardous rebar that was remaining in the river bed at the Elwha Dam site. The rebar was protruding from the dam foundation and created a safety hazard for the public. The project also included explosive demolition of numerous large boulders in the vicinity of the former dam sites that created flow constrictions with large velocity gradients and hydraulic jumps. The demolition objective was to improve passage conditions for the numerous species of trout and salmon that migrate up the Elwha River. This report documents the rebar removal and boulder demolition and provides recommendations for techniques to remove the remaining Elwha Dam foundation in the future if desired by NPS.

Subject Categories:

  • Civil Engineering
  • Ecology

Distribution Statement:

APPROVED FOR PUBLIC RELEASE