QES has extensive direct field experience in the design, drilling and construction of monitoring and production wells using direct mud rotary, hollow-stem auger, air percussion, and reverse circulation air rotary dual-tube methods, along with groundwater and soil sample collection and characterization and aquifer testing and analysis programmes.
That field experience carries into the interpretation. Conceptual site models are built from data our own people watched being collected, which is what makes them defensible later in a feasibility study or a deposition.
QES served as oversight supervisor for US EPA Region IX and the RWQCB Los Angeles Region, observing subcontractor field activities at several operable unit areas. Activities included drilling, construction, development and sampling of monitoring wells up to 900 feet below ground surface, along with Westbay multiport monitoring systems.
As project manager, QES characterized subsurface conditions at a site where groundwater is impacted by chlorinated volatile organic compounds and petroleum hydrocarbons. Through upgradient off-site groundwater monitoring, QES showed the chlorinated compounds were likely from an upgradient off-site source and focused the remaining investigation on a hydrocarbon plume related to a former gasoline station. A geophysical survey identified a potential on-site source.
As lead hydrogeologist for the final phase, QES reviewed hydrostratigraphic and water quality data from over 100 wells and borings to refine the conceptual model of a complex hydrologic system that includes structurally deformed and faulted water bearing units. The interpretation assessed groundwater and soil vapour migration pathways and evidence of potential impact to offsite receptors, supporting the risk assessment and feasibility study phases.
As lead hydrogeologist, QES developed design alternatives for leachate collection within the landfill, containment of leachate migrating outward from the perimeter, and remediation of contaminated groundwater offsite. Final alternatives included barrier walls and collection wells at the perimeter, with monitored natural attenuation or groundwater extraction in offsite regions.
QES compared each alternative on technical efficiency, protection of human health and the environment, cost and other factors in accordance with the nine National Contingency Plan criteria, and presented the detailed analyses, conceptual alternative design plans and comparative results to US EPA and major potentially responsible parties.
QES performed interim corrective action screening at a former perchloroethylene recycling facility. The RCRA Facility Assessment received commendation from the Department of Toxic Substances Control. Corrective action technologies evaluated for dense nonaqueous phase liquid and dissolved phase contaminants included six-phase soil heating, barrier wall containment, funnel and gate technology, soil vapour extraction, multi-phase extraction and monitored natural attenuation.
Call or write and you will speak with the people who will do the work. We will tell you plainly what a defensible path forward looks like.