Groundwater Treatment System for Chemical Depot - Hermiston, OR

The United States Army Umatilla Chemical Depot (UMCD) is a 20,000-acre military reservation established as an ordnance depot and demolition activity in 1941. It is located in northeastern Oregon approximately 3 miles south of the Columbia River. The UMCD mission included chemical munition storage, incineration of stored nerve gas ordnance, and site remediation.

A 1,300 gallon per minute groundwater treatment plant was constructed, operated and maintained at a site identified as the Explosives Washout Lagoon Groundwater Operable Unit Three, located in the east-central portion of UMCD. At one time, the site consisted of two adjacent unlined lagoons, each approximately 25 by 75 feet and 6 feet deep. The lagoons were used for infiltration of wastewater from the Explosive Washout Plant during the 1950s and 1960s. During their operation, the lagoons received approximately 85 million gallons of wastewater containing high concentrations of explosives.

During fieldwork, an experimental field analysis for explosives in groundwater was applied. The result was the ability to consistently achieve a detection range of 1.5 to 2.5 ppb on a 4-hour turnaround time in its on-site field laboratory, a detection limit matched by few commercial laboratories.

As part of this contract, a web-based site for data management and data sharing was designed and constructed, built to facilitate the Army Corps' management and review of the site cleanup.

Project Performance

During the two years the treatment system was operated, all requirements of the contract and applicable regulatory requirements were met, there was zero incidents of lost time due to worker injury/safety issues, and operational costs were reduced over 20%.