Description
Bethel conducted a supplemental remedial investigation (SRI) at a former Atlas “D” intercontinental ballistic missile (ICBM) launch site near Cheyenne, Wyoming. Field activities conducted in 2018 included collection of groundwater samples from 16 existing monitoring wells in an effort to update the current understanding of the trichloroethylene (TCE) plume impacting the site’s groundwater. Existing monitoring wells were surveyed for accurate horizontal and vertical coordinates to refine site data for groundwater flow direction and gradient. The project included advancing soil borings and installing monitoring wells at select downgradient locations and collecting groundwater samples from new and existing monitoring wells. 11 of the planned 16 monitoring wells were installed in the fall of 2019. A Bethel senior geologist led the investigation and logged continuous soil core from each of the soil borings, determined the appropriate depth to set the well screen to capture contamination contained in the first unconfined aquifer, and oversaw each 4-inch diameter well construction. Monitoring well depths ranged from 170 to 245 feet. In addition to the senior geologist, Bethel’s field team included a chemist who field screened for TCE using a parts per billion precision photoionization detector. Soil samples were collected for TCE analysis from each soil boring and also from the drill cuttings and well development/purge water.
The Bethel field team installed the remaining five monitoring wells, developed all 16 of the new wells and sampled all new and existing wells during the summer of 2020. The sampling event generated over 1,000 gallons of TCE-impacted water that was contracted to Veolia North America for off-site disposal.
Bethel reported findings and conclusions of the TCE investigation in a report which included updated geology and hydrogeology data based upon continuous coring of the 16 new wells, TCE contaminant mass calculations, cross-sections figures of plume profile, groundwater flow map, and a TCE concentration contour map. The Bethel chemist populated the “event planning” for FUDS Chem and validated the laboratory data through FUDS Chem.
Bethel has developed extensive experience installing deep wells as required of this contract.
Bethel effectively communicated with the US Army Corps of Engineers prior to and during site work and worked with the client to solve problems that were encountered, such as access to well locations on private land.
Client
US Army Corps of Engineers, Omaha District
Location
FE Warren AFB, Wyoming
Period of Performance
8/2017 to 12/2020
Contract Value
$1.5M
Contract Numbers
W9128F-16-D-0019;
Task Order W9128F17F0096
Work Performed
Deep soil boring and well installation
Groundwater sampling in deep wells
Roto-Sonic Drilling methodology
Vertical survey of well casing elevations
Well development