Remediation of Petroleum Hydrocarbon Impacts in Soil and Bedrock
XCG was retained by the owner of an active truck maintenance and long-term parking facility to provide site assessment and remediation services to facilitate the sale of the property. The property also operated an on-site fuelling station.
XCG undertook a subsurface investigation which identified petroleum hydrocarbon (PHC) impacts in soil near the on-site fuelling station. XCG developed and implemented a remedial work plan based on excavation and off-site disposal of impacted soil. The remedial excavation extended to an approximate depth of 4.5 metres, where the excavation was stopped upon reaching the bedrock surface. Approximately 285 tonnes of impacted soil was excavated and disposed off-site at an Ontario Ministry of the Environment and Climate Change (MOECC)-licensed facility.
A bedrock monitoring well was installed in the area of the remedial excavation using HQ rock coring techniques to assess permeability of the saturated bedrock, and to assess groundwater quality in the vicinity of the former soil impacts. Sampling results confirmed that the groundwater in the vicinity of the remedial excavation was heavily impacted by PHC. XCG installed four additional monitoring wells using air rotary techniques to delineate the extents of the PHC impacts to groundwater, and also designed and directed construction of a buried percolation trench at the base of the excavated area to facilitate gravity-fed injections of in-situ chemical oxidation (ISCO) solutions. Delineation through groundwater sampling confirmed that the PHC impacts were limited to the area of the remedial excavation. XCG completed two ISCO injections into the percolation trench using a water-based solution of commercially available remediation products. This work was performed under XCG’s mobile Certificate of Authorization, through which the MOECC authorizes XCG to operate a mobile treatment unit for the remediation of soil and groundwater. After the second ISCO injection event, the concentration of PHC in groundwater in the area of the remedial excavation had declined such that the water quality met the appropriate standards (potable groundwater conditions).
XCG issued a report summarizing the remedial and investigative activities, which was submitted for review to the purchaser’s financial institution as part of their due diligence requirements. The financial institution was satisfied with the activities and findings described in XCG’s summary report, and the purchaser obtained the necessary financing to acquire the property.