Location: Clackamas, Oregon
Client: National Consulting and Engineering Firm
Contract Value: $1,000,000
Camp Withycombe, located in Clackamas County, Oregon was established as a training camp in 1909. Throughout its history, the camp was used as a rifle range, mobilization camp, and supply depot. Originally known as the Clackamas Firing Range, in 1934 the facility was designated a federal military reservation and named Camp Withycombe, after former Oregon governor, James Withycombe. Throughout World War II, the site was used as a United States Army barracks and its firing ranges received extensive use by the U.S. Army, the U.S. Marine Corps, the Federal Bureau of Investigation, police, and civilians.
Currently owned by the Oregon Military Department, the 77+ acre site still serves as a training facility, supply depot, and equipment repair facility for the National Guard but the rifle range is now closed. Decades of use as a firing range caused an extensive amount of lead contamination and AEC was retained by the Oregon Military Department in 2008 to perform an interim remedial action of the rifle ranges area.
The overall remedial action performed by AEC included excavation of ~30,000 cubic yards of lead-contaminated soil in range impact areas. Prior to the start of excavation, the site was cleared of all vegetation, logged via chainsaw and free felling methods and all timber was salvaged. AEC then constructed a 300 ft. long temporary gravel roadway behind the range backstops that would allow clear access to the slope, the construction area, and areas behind the backstops.
There were also some small wooden structures and a 3-sided concrete wall that required demolition prior to the start of excavation. In total, we demolished and recycled 33 target structures. The 34th target structure was removed and transported to the Camp Withycombe museum.
The majority of the scope involved excavation, stockpiling, sampling, analysis and characterization of ~30,000 yards of lead-shot contaminated soil. AEC began this portion of the work by defining remediation grids according to contamination depth. AEC worked in a stair stepped manner along the slope from top to bottom ensuring our equipment was on flat stable ground at all times versus working at an uphill angel. Contaminated soil was loaded directly onto haul trucks and disposed of offsite according to federal and state regulatory requirements at an approved landfill. There was a small wetlands area that was not to be disturbed during our operations. AEC clearly delineated the wetlands and implemented strict erosion and sediment control plans to protect the wetlands at all times.
After excavation operations we installed a 2-acre (87,120 square feet) asphalt pad which was used in the next soil washing phase of work at the site. The asphalt pad was 4-inches thick and compacted in two 2-inch lifts over a compacted 4-inch thick subgrade of ¾-inch crushed rock. The pad included 12 drainage basins to collect rainwater and the asphalt around each basin shall be sloped to direct rain water to nearest basin.
Finally, the site was backfilled and compacted with clean soil and AEC provided final hillside restoration services which included re-vegetation, hydroseeding, and planting. AEC completed this project on-time and within budget using 100% of AEC resources.