Remedy in Place, Sites 32/33, Military Ocean Terminal Concord
Ahtna completed an in progress complex firm fixed price remediation at MOTCO under a performance-based contract to achieve Response Complete for sites MOTCO-032 Unit 7 Mosquito Abatement Ditches and MOTCO-033 Lost Slough. The project began in 1986 with previous contractors performing multiple phases of investigation, risk assessment, and remedial design leading up to the final remediation construction approach and execution in 2015. Ahtna performed the work as an expedited remedial action that involved a complex approach to the placement of an in situ cap in a tidally-influenced brackish wetland – a critical habitat for many federal and state-listed endangered species. The cap consisted of approved bay mud dredge spoils provided by the client, placed uniformly in the base of the channels. The caps were designed to isolate the contaminated sediments from benthic organisms. Ahtna constructed the caps in two phases by air-lifting Supersacks containing approximately 2,500-lbs of dried bay mud using helicopters that dropped the soil into place without landing to avoid impact to the sensitive wetland.
This project was featured in the Society of American Military Engineers The Military Engineer. To read the article, visit this link: Nine Days in California
- Remedial Design