Risk Assessment

Site Characterization, Remediation, and Human Health Risk Assessment for Pesticide Contaminated Property, Salt Lake City Mosquito Abatement District
The Salt Lake City Mosquito Abatement District retained SAGE to assess the degree and extent of pesticide contamination at their former facility.  An extensive site characterization effort confirmed the presence of high concentrations of pesticides (including DDT) in both soil and ground water. SAGE developed a corrective action plan and performed the remediation, which consisted of the excavation and off-site disposal of over 3,000 tons of pesticide-contaminated soil, including over 1,000 tons that required incineration as hazardous waste. 

Following the soil remediation, SAGE prepared a human health risk assessment using a residential exposure scenario. This effort included modeling the risk due to the ingestion of home-grown produce by analyzing pesticide uptake by existing site vegetation.  Risks from residual soil and ground water contamination were determined to exceed the requirements for clean closure.  Subsequently, SAGE prepared a Site Management Plan that included deed restrictions and periodic ground water monitoring.  We are conducting the required on-going ground water monitoring and reporting.

Coal Tar Site Investigation, Feasibility Study and Risk Assessments, Utah Power/PacifiCorp
Contamination was discovered during the construction of the Jordan Substation, located adjacent to the Jordan River in Salt Lake City.  The contamination appeared to be associated with a coal and fuel oil powered steam plant that had operated on the site from 1910 until the mid-1980s.  SAGE conducted detailed subsurface investigations that confirmed the presence of coal tar-like contamination in subsurface soil, river sediments, and ground water.  The most significantly contaminated soils and a layer of free product were located on top of a clay layer about 20 feet below ground surface and extending underneath the Jordan River.

SAGE prepared a Technical Impracticability Evaluation report for submission to the Utah Division of Solid and Hazardous Waste (DSHW), demonstrating that remediation was not technically or economically feasible due to the nature and location of the contamination.  SAGE then prepared a human health risk assessment that evaluated risks of leaving the contamination in place for both current industrial and proposed future recreational use of the property, as well as an ecological risk assessment.  These assessments indicated that risks were acceptable under both the current and proposed future use scenarios.  We prepared the Site Management Plan to ensure that appropriate controls are in place.

Soil Remediation Plan with Risk-Based Remediation Goals, Risk Assessment, and Site Management Plan, Utah Power/PacifiCorp
SAGE conducted a multi-phased site investigation that identified petroleum hydrocarbon and solvent contaminated soil and ground water beneath Annex 1, a former Utah Power vehicle maintenance facility.  We prepared a Report of Investigation that documented multiple sources of contamination, including surface spills, leaking underground storage tanks, and drain fields that had been used for the disposal of waste water.  We then prepared a Soil Remediation Plan that used a risk assessment approach to calculate Remediation Goals (RGs).  Soil contaminated in excess of the RGs was to be excavated and disposed of off-site to prevent continued degradation of ground water. SAGE petitioned the Utah Division of Solid and Hazardous Waste to request a re-classification of the regulatory status of the soil to be excavated, which had been characterized as hazardous waste during earlier remediation efforts. The petition was approved, allowing excavated soil to be disposed of as non-hazardous waste and reducing remediation costs by over 50%.  After follow-up bioremediation activities were completed, SAGE prepared a human health risk assessment that evaluated both residential and commercial exposure scenarios. Risks were determined to be acceptable, and we prepared a Site Management Plan that supported the redevelopment of the property as a truck stop.