|Client:||Atlas Copco Canada Inc.|
|Location:||1157 Blair Road, Burlington, Ontario|
XCG was retained by Atlas Copco Canada Inc. (ACCI) to conduct site assessment and remediation activities at an industrial facility located at 1157 Blair Road, Burlington, Ontario. Previous environmental investigations completed by another consultant identified the presence of elevated concentrations of chlorinated volatile organic compounds (CVOCs) in both the shallow overburden and deep bedrock water bearing zones at the site.
ACCI retained XCG in 2001 to further investigate and delineate the extent of CVOC-related impacts and to develop a remedial action plan (RAP) to address the elevated CVOC concentrations. XCG completed additional subsurface investigation activities to further delineate and characterize the groundwater quality on-site. XCG supervised the installation of multiple groundwater monitoring wells within both the shallow overburden and deep bedrock water bearing zones. The deep bedrock monitoring wells were installed using advanced telescopic drilling methods which involved the installation of steel casings grouted directly into the bedrock to prevent the potential downward migration of CVOC-impacted groundwater from the shallow overburden aquifer to the deeper bedrock water bearing zone during drilling activities.
In addition, in 2001, XCG completed further soil investigation activities on-site to address concerns expressed by the Ontario Ministry of the Environment and Climate Change (MOECC) about the potential presence of contaminated soil beneath the on-site building. Based on field screening, a soil vapour survey and laboratory analytical results, XCG concluded that no evidence of significant concentrations of total organic vapours (TOVs) and no significant contaminated soil was present on-site. As such, the remediation effort completed to date by XCG has been focussed on the treatment of CVOC-impacted groundwater.
The groundwater remediation program completed on-site to date is based on an in-situ chemical oxidation (ISCO) approach using sodium and potassium permanganate injections. ISCO using permanganate was selected due to its high persistency, effectiveness for treating CVOCs and the favourable oxidizing groundwater conditions identified at the site. The groundwater remediation activities have been conducted primarily using an automated sodium permanganate injection system, which has been in operation since 2004. The system is operated continuously and involves the automated injection of a dilute solution of sodium permanganate into 18 injection wells to promote the degradation of CVOCs within the groundwater. The injection wells are screened within the deep bedrock water bearing zone and are located along the down-gradient property boundary. On a monthly basis, approximately 175 litres of a 40-percent solution of sodium permanganate is diluted with potable water and injected into the subsurface by the automated injection system.
In addition to the ongoing operation of the automated injection system, on- and off-site remediation is also conducted using injection wells that were specifically constructed for the purpose of conducting pressurized injections. These on- and off-site injection wells are screened within the deep bedrock water bearing zone. Between 2001 and 2013, a total of seven pressurized injection wells were installed on- and off-site. XCG completed ISCO injections between 2013 and 2014, using these pressurized injection wells, injecting a total of 32,000 litres of a sodium permanganate solution directly into the subsurface under pressures generally ranging from 69 to 690 kPa (10 to 100 psi). In addition, periodic manual/gravity-based injections have historically been completed at on-site monitoring well locations selected for their proximity to CVOC ‘hot spot’ locations.
In 2013, XCG was retained by ACCI to complete a screening-level risk assessment (SLRA) to develop site-specific groundwater remediation criteria for the site. The overall conclusion of the SLRA was that the current site maximum concentrations of CVOCs in the groundwater exceed the SLRA-derived standards, which were more restrictive than the currently applicable generic MOECC standards. The most recent, 2017, groundwater monitoring data indicates that CVOCs concentrations are below the MGRA-derived, site-specific criteria. However, although the CVOC concentrations have significantly decreased, they still do not meet the applicable generic MOECC standards. Therefore, as requested by the MOECC, XCG continues to manage the permanganate injection program which includes the continuous operation of the automated injection system and the completion of target ISCO injections as needed, to further reduce elevated CVOC concentrations still present in localized areas on- and off-site.
In addition to completing environmental investigation and remediation activities, XCG’s involvement with this project also included negotiating site access with neighbouring property owners for off-site drilling/remediation, reviewing historical information for neighbouring properties to identify potential contaminating activities, communicating with the local municipality and the MOECC on behalf of ACCI, and assisting ACCI in negotiations with prospective site purchasers.
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