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Challenge
Mundell was retained to provide consulting services at a former dry cleaner facility in Rochester, Indiana. Delineation of chlorinated volatile organic compound (cVOC) impacts to soil and groundwater was needed after initial impacts were identified during the investigation of a neighboring Bulk Petroleum Terminal that is part of the Leaking Underground Storage Tank (LUST) program. The building is currently occupied by a closed restaurant and a tobacco shop. The site is located in a One Year Time-of-Travel (W-1) municipal wellfield for the City of Rochester.
Action
Mundell performed extensive investigation activities on the Site and surrounding properties in order to delineate the nature and extent of cVOC impacts. A geophysical assessment was conducted to identify possible subsurface conduits and assessment of the sewer utility network was also completed to identify potential transport pathways and vapor intrusion issues.
Results
Mundell identified chlorinated impacts in groundwater that had migrated 800 feet north of the site onto a local municipal golf course and within 700 feet of local municipal water supply wells. Vapor intrusion (VI) investigations indicated the presence of cVOC vapors beneath and within the restaurant side of the Site building at concentrations exceeding associated sub-slab and indoor air VI screening levels. To interrupt this potential VI pathway and protect occupants from potential vapor exposure, Mundell oversaw the installation of install vapor mitigation systems.
Complicating factors at this site include the presence of two saturated units – an upper semi-perched unit and the lower primary aquifer, separated by a discontinuous clay layer. Additionally, the LUST site is located to the immediate west of the site, which resulted in a comingled plume of petroleum and chlorinated impacts.
Mundell completed and submitted a Corrective Action Plan to IDEM and has received approval with comments. Remediation will consist of the construction of permeable reactive barriers (PRBs) via multiple lines of in-situ injection products that will work to break down cVOCs using both abiotic and biological methods. Mundell is currently working on the logistics of the remedial plan and aims to start remediation activities on-site soon.
