A cleanup number is an argument, not a constant. QES negotiates site-specific criteria supported by fate and transport modelling, risk-based soil gas values, statistical characterization methods and site-specific risk assessment conclusions.
Agreeing a defensible number that leaves protective material in place has repeatedly cut the volume of soil requiring excavation and off-site disposal, at substantial cost saving to clients.
QES served as oversight supervisor observing subcontractor field activities at several operable unit areas, including drilling, construction, development and sampling of monitoring wells up to 900 feet below ground surface and Westbay multiport systems. QES also participated in cost allocations and negotiations between potentially responsible party steering committees and US EPA.
QES used fate and transport modelling to develop soil screening and cleanup values exceeding the levels in RWQCB Los Angeles Region guidance, representing concentrations that can be left in place without posing a risk to groundwater. The agencies agreed to the approach, which used the VLEACH analytical model and a groundwater mixing cell model. At the former Unocal site this minimized the volume of soil requiring excavation and off-site disposal, and at Plant 42 it limited vadose zone remediation and soil boring investigation.
QES negotiated closure of a 25,000-gallon petroleum underground storage tank on a Port property acquired through eminent domain. Monitored natural attenuation was successfully negotiated after screening with the BIOSCREEN model. The Board approved a site characterization that included geophysical and soil gas surveying for source identification, plus HydroPunch and quarterly groundwater monitoring to support the attenuation assessment.
QES achieved regulatory closure with unrestricted land use for an active chemical production facility where organic compounds were formerly used. Closure followed 20 years of soil gas, soil and groundwater investigation and remediation. Site-specific soil gas screening values were derived using the Johnson-Ettinger model.
QES negotiated a soil management plan for organochlorine pesticide-impacted soil during site grading, and supported counsel in negotiations with the County District Attorney over representative average concentrations in stockpiled soil. Both methods were approved by the County and off-site disposal was minimized to hotspot areas exceeding US EPA Region IX and California preliminary remediation goals.
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.