Wilder Projects

Explosives Washout Lagoon Contaminated Soil
Remediation Phase 1 – Umatilla Depot Activity

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Project Location: Hermiston, Oregon

Client: U.S. Army Corps of Engineers

Construction Cost: $1.3 million

Wilder’s Role: Prime

Construction Period: 11/93 – 11/94

Project Highlights
TNT and RDX Contamination On-Site Field Screening Preparation of Seattle district approved Remedial Action Management Plan UXO avoidance Completed within budget Completed on schedule Customer satisfaction - Outstanding Rating by the Seattle District

The remediation of the Explosives Washout Lagoons at the Umatilla Army Depot was one of the first efforts by the Seattle District to deal with TNT and RDX contamination. The remediation consisted of excavating 9,000 CY of TNT and RDX contaminated soil. The soil was transported to an on-site material handling area where it was screened to separate it into three size classifications: rocks greater than two inches, material between one quarter and two inches, and fines less than one quarter inch in diameter. Wilder placed soil above cleanup levels inside a 20,000 SF building constructed by a Wilder subcontractor. This building is being used under Phase II for composting the contaminated soil. Associated work included clearing and grubbing, demolition and removal of contaminated features and site restoration.

After performing the physical separation, Wilder sampled and analyzed the soil to determine if TNT/FDX contaminants were present in concentrations greater than cleanup levels. In addition to sampling the screened material, Wilder sampled on 61 grids associated with the explosives washout lagoons to verify all contaminated soil was removed. Samples were analyzed by field screening in an on-site laboratory with off-site laboratory confirmation. In order to achieve significant cost savings, Wilder proposed a modification to the roof design and paint selection of the treatment building, and segregated clean soils through a visual appearance field screening technique developed by Wilder.

Schedule Successes. Wilder completed the project with a minimal schedule impact despite the need to excavate significant additional contaminated material over the engineer’s estimate.

Quality. Wilder received an Outstanding Contractor performance rating on this project from the Seattle District. The following is a quote from Kent R. Paul, the Contracting Officer for the project:

“Fort Lewis area office rated you outstanding for effectiveness of management and safety. In essence your staff and subcontractors provided a superb facility, on time, to the Army. I received numerous compliments on your work. You can be proud of your accomplishments.”

INNOVATIVE APPROACHES & TECHNOLOGIES

Value Engineering. During the final portion of the soil excavation, Wilder separated the clean overburden from the contaminated soil on the basis of soil material type and color. Using our experience and the data compiled from the on-site laboratory, we were able to accurately identify TNT contaminated soil based on appearance factors associated with the TNT contamination. By visually determining clean soil, Wilder reduced the total volume of soils to be treated. This provided a substantial cost reduction to the Seattle District on subsequent handling and treatment.

Wilder substituted a rubber-tired excavator for a tracked excavator to reduce the risk of explosions caused by sparks.

Problem Solving. The Seattle District relied on Wilder to offer cost effective solutions to work scope changes encountered during remediation. Wilder’s strong on-site management responded promptly by applying sound civil construction principals and problem solving ability to offer cost effective solutions without major schedule impacts.