Client: USACE Alaska
Location: St. Lawrence Island, Alaska
Scope of Work:
- Supplemental soil investigation
- Soil removal action
- Sediment dredging pilot test and full implementation removal action
- Other tasks included landfill cap maintenance and inspection, groundwater sampling to track monitored natural attenuation, monitoring well maintenance and decommissioning, miscellaneous metal debris removal, background sampling, LUC signage inspection and replacement, and public meetings.
Brice performed fieldwork at the Northeast Cape FUDS at Site 7, Site 8, Site 28, Site 15, the Main Operations Complex (MOC), and the gravel airstrip and gravel road. Our scope of work included site preparation (road and airstrip repairs to allow safe access to the sites), three major tasks consisting of a supplemental soil investigation at Site 8, soil removal action at Site 15, and sediment dredging pilot test and full implementation removal action at Site 28. Other tasks included landfill cap maintenance and inspection, groundwater sampling to track monitored natural attenuation, monitoring well maintenance and decommissioning, miscellaneous metal debris removal, background sampling, LUC signage inspection and replacement, and public meetings.
Supplemental Soil Investigation. To delineate the extent and magnitude of POL-contaminated soil at a historical pipeline release location at Site 8, we collected soil samples from 30 locations using a track-mounted, direct push Geoprobe drill rig and hand auger. Samples were submitted for analysis of DRO and RRO (with and without silica gel analysis) and PAHs. The areas exceeding the site-specific cleanup levels for DRO and PAHs were identified and delineated.
Sediment Removal Pilot Test and Removal Action. Brice performed a pilot test to remove contaminated sediment using suction dredging from several muskeg tundra ponds and streams, then performed an in-field evaluation of the technology with the client before implementing a full-scale removal action. The removal action consisted of completely removing loose contaminated sediment from the target areas. We transported the dredged slurry to a central water processing and treatment area, up to 1,000 feet away from the dredging areas, where sediment was dewatered for containerization and all water was treated though a granular activated carbon filter and pumped back onto the project site. The recovered sediment was smaller in volume than estimated from a previous sediment mapping effort; Brice revised the sediment mapping methodologies in-field to produce better estimates in future mapping.
Soil Removal Action. Brice removed 2,200 cy of petroleum contaminated soil from 12 to 15 feet below ground surface. We stockpiled, sampled, and covered approximately 2,000 cubic yards of overburden, then excavated to several feet below the water table. To containerize the wet soil below the water table, we removed and stockpiled the soil on a lined slope allowing it to drain back into the excavation for 4 to 5 days before bagging for transport and disposal. Confirmation sampling for DRO after completion of excavation confirmed all contaminated soil exceeding the site-specific cleanup level had been removed, and all stockpiled soil could be used as backfill.
Brice mobilized equipment to the site with a Brice Marine barge and mobilized personnel to the site by air charter and housed the field team in a life support camp for the duration of fieldwork (the FUDS is only accessible by air, water, and all-terrain vehicles). We used tracked vehicles for any off-road travel only when necessary to avoid impact to the tundra ecosystem as well as cultural resources.
Brice completed the work on time and on budget and with zero safety incidents.