|Client:||Leggett & Platt Inc.|
|Location:||66 Jutland Road, Etobicoke, Ontario|
2015 – 2018
XCG was retained by Leggett & Platt Inc. (LPI) to provide engineering services in relation to the investigation of soil and groundwater quality and subsequent remediation of a former industrial facility, located at 66 Jutland Road, Etobicoke, Ontario. Phase I and II Environmental Site Assessments (ESAs) completed by XCG identified the presence of elevated concentrations of chlorinated volatile organic compounds (CVOCs) within the shallow overburden soil and groundwater at the site. To meet LPI’s needs and to manage potential liabilities related to off-site migration of CVOC-containing groundwater, XCG designed a Daramend-based permeable reactive barrier (PRB) along the east property boundary. Daramend is a pelletized form of controlled-release carbon and zero valent iron (ZVI). The PRB was installed in June 2015 by Ground Force Environmental, a remedial contractor, under XCG’s supervision.
Prior to the construction of the PRB, XCG completed groundwater monitoring activities to confirm the hydrological and geochemical properties of the shallow groundwater on-site. The information and data generated during these monitoring activities were used to finalize the design of the PRB. Based on the monitoring results, groundwater pre-treatment using in-situ chemical reduction (ISCR) was completed to establish stronger groundwater reducing conditions prior to PRB construction. The ISCR pre-treatment activities were completed using a direct push drilling rig to inject EHC-L® (a micro-emulsion of a controlled-release, food-grade carbon, nutrients, and iron) into the shallow subsurface, up-gradient of the proposed PRB location.
The PRB was constructed using a total of 13,000 kilograms of Daramend mixed on-site with imported coarse sand at a concentration between 2 and 8% (by volume). The mixing of Daramend and sand was completed using a pre-washed cement mixer truck. The PRB was constructed by excavating a 120-metre long, 1.5-metre wide trench along the east property boundary into the top of the competent shale bedrock (i.e. PRB keyed into the bedrock). In order to install the PRB directly adjacent to the fenced property boundary, the trench was excavated using a hydraulic excavator and a shoring box. The shoring box was used to prevent caving of the trench walls and to ensure a consistent PRB width along its entire length. Once excavated to the target depth, the trench inside the shoring box was backfilled with Daramend mixed with coarse sand. In addition, coarse sand was placed in the trench on the outside of the shoring to act as a sand filter pack between the Daramend and native soil. Once completely backfilled, the top of the PRB was covered with a woven geotextile filter fabric and a native soil cap was installed to match the surrounding grade.
In order to monitor the performance of the PRB, monitoring wells were installed up-gradient, within and down-gradient of the PRB. XCG completed groundwater monitoring activities to evaluate the performance of the PRB and the results indicated that overall CVOC concentrations down-gradient of the PRB have decreased between 90 and 100%.
In addition to completing on-site remedial activities, XCG’s involvement with this project also included negotiating site access with neighbouring property owner for off-site investigation/delineation, reviewing historical information for neighbouring properties to identify potential contaminating activities and assisting LPI in negotiations with prospective site purchasers.
Project Gallery – Click an image to enlarge.