ART staff completed a site characterization investigation and a feasibility study for Clean Closure of the Hidden Glen Landfill located in Napa County, California. The investigation, which was performed for the City of Napa, a garbage company and a confidential client, indicated the presence of high concentrations of lead in the landfill debris and the leachate. The scope of work included drilling, sampling and testing of landfill debris and leachate, preparation of a feasibility study which included the evaluation of the most cost effective method for the treatment of lead contaminated soil, cost estimation of the recommended remedial design and remedial construction management of the site, and regulatory negotiations for recycle/reuse of the treated landfill material. The approximate quantity of landfill debris impacted with lead for treatment was approximately 20,000 cubic yards.

ART staff provided planning and field oversight for the excavation and off-Site disposal of more than 80,000 cubic yards of contaminated soil at a former industrial site in northern California. The soil was affected by various contaminants included PCBs, hydrocarbons, and metals. Planning documents included Remedial Action Plan, Air Quality Monitoring Plan, Sampling Plan, Grading Plan, SWPPP, and Health and Safety Plan.

ART staff used vapor extraction in clay soils at a former dry cleaner in northern California to remove DNAPL PCE from soil and groundwater. The system was designed using large diameter extraction wells to facilitate removal of significant vapor at relatively low vacuum. The project successfully removed over 750 pounds of PCE in less than 6-months, and facilitated prompt soil and groundwater cleanup.

ART staff evaluated several remedial options for highly contaminated gasoline impacted site before applying developed a chemical oxidation system The project involved injection hydrogen peroxide (7%) into the subsurface using a series of injection wells spaced on a 30-foot grid pattern. The system was used to remediate both unsaturated and saturated soils.

ART staff developed a 3-D numerical model to simulate groundwater flow in a severely over drafted aquifer. The model was used as a tool to predict required extraction rates to contain a plume of hexavalent chromium impacted groundwater that threatened more than 200 private drinking water wells. The model was used to locate and operate new extraction and injection wells. The model was an important tool in preventing impacts to the private wells while minimizing contribution to the localized over draft problems.

ART staff conducted field tests at the petroleum hydrocarbons-impacted site to evaluate the feasibility of bioventing, including bench-scale laboratory study and field-scale in situ respiration test. The scope of work included the remedial design and installation of wells over the one-acre contaminant plume, and the monitoring of the bioventing system until attainment of clean up goals.