For this project, BERS worked jointly with a diverse team of partners and subject matter experts to open, dewater, backfill, re-cover, and reseal 30 Spartan Tactical Launch Stations (TLSs) at the Stanley R. Mickelsen Safeguard Complex. Previously analyzed water from the TLSs indicated that some of the structures contained varying concentrations of cadmium and chromium exceeding Resource Conservation and Recovery Act (RCRA) regulatory levels which needed immediate action. Project activities commenced within 30 days of initial award and involved site preparation including utility locates and installation of a new access gate, access roads, staging areas, and erosion control measures. Services required opening the protective covers on the launch chamber and the exhaust duct as well as the personnel access hatch on the mechanical and electrical equipment vault. Then, water was removed from the Spartan TLS structures and treated on-site. As the dewatering of the TLS structures progressed, the project team conducted confined space entry into the equipment vaults of each TLS following strict safety procedures including air monitoring, donning of harnesses and retrieval devices, and use of a dedicated entry attendants. During this phase, personnel sealed off potential entry points for future water infiltration and secured the manways to allow for future backfill with flowable fill.
An on-site water treatment system was developed and deployed to remove metals and polychlorinated biphenyls in order to treat the contaminated water. After treatment, the water removed from each TLS was tested to ensure that it was below RCRA regulatory levels and was then transported off site for disposal as clean. This on-site treatment resulted in a cost avoidance of approximately $1.7M versus offsite disposal as hazardous waste.
Finally, the TLSs were backfilled with sand then capped with a 1-foot-thick slab of structural concrete with rebar extending to the interior walls of the launch chamber and the exhaust duct; effectively re-covering and resealing the Spartan TLSs. All hazardous materials were removed from the site and disposed of in accordance with applicable federal, state, and local regulations. All required waste profiles, bills of lading, and hazardous waste manifests were prepared in accordance with applicable regulations.
