The primary cleanup vendor for the Energy Department’s Hanford Site in Washington state has lined up a subcontractor to stabilize three underground structures with grout, according to a Tuesday press release.

Jacobs subsidiary CH2M Hill Plateau Remediation is issuing a $3.9 million subcontract to engineering firm White Shield, of Pasco, Wash., to design and apply engineered grout at three sites near the former Plutonium Finishing Plant.

The structures – the 216-Z-2 Crib, 216-Z-9 Crib, and 241-Z-361 Settling Tank – all received liquid waste during Hanford’s plutonium production days. As a result, they contain residual radioactive and chemical contamination.

All three of these aging facilities are in danger of collapse. The Energy Department, which is seeking public comment on the plan to stabilize the sites, wants to avoid a repeat of the May 2017 partial collapse of Tunnel 1 at Hanford’s Plutonium Uranium Extraction (PUREX) Plant. The public comment period started March 23 and runs through May 22. A public hearing on the matter has been postponed from March 26 due to concern over COVID-19.

The work is considered time-sensitive, but not an emergency. Therefore, initial planning and design of the necessary grout mix and conveyance system will be done remotely, CH2M said in the press release. Hanford has reduced its on-site staffing dramatically as a result of the pandemic.

Most physical work at Hanford is currently suspended due to COVID-19. At some point after normal operations resume, trucks will deliver the grout that will be piped into the structures. Workers will also lower lights and cameras underground in order to monitor grout flow.

White Shield is a Native American-owned company named after Chief White Shield of the Arikara Tribe, according to its website.