KB-1® Bioaugmentation at a Toronto Area Dry Cleaner Site

Project Highlights

Effective bioremediation achieved in low permeability soils at a retail dry cleaner in the Greater Toronto Area (GTA).
cDCE stall corrected within 8 months of bioaugmentation, with no vinyl chloride accumulation.
Ontario regulatory standards (Table 3) were achieved for all chlorinated volatile organic compounds (cVOCs) approximately 1.5 years after KB-1® bioaugmentation.

Summary

Client: Terraprobe Inc.
Site Location: Greater Toronto Area
Project Duration: 2012-2014
Services Provided:
- KB-1® Bioaugmentation
- Gene-Trac® Testing

KB-1® (vessel bottom left) injection at the GTA site using direct push technology

Problem Definition

An active retail dry cleaner required groundwater remediation activities that were non-disruptive to the current occupants and adjacent parking areas. The silty sand subsurface materials were low permeability (hydraulic conductivity of 10-7m/s). The groundwater contained low concentrations of PCE (tetrachloroethene

[~50 μg/L]) and associated degradation products: trichloroethene (TCE~[50 μg/L]) and cis-1,2-dichloroethene (cDCE [~20μg/L]). Gene-Trac® tests indicated Dehalococcoides (Dhc) were not detected, or were present at low abundance, consistent with the observed cDCE stall and lack of less chlorinated degradation products.

Solution

Direct push technology including a high pressure grout pump was used at 29 locations to inject a total of 2,600 kg of EHCTM. Three injection rounds were performed to limit the potential for daylighting due to the low permeability materials. During the 3rd injection round twenty liters of KB-1® was co-injected with EHCTM into nine locations.

Notable Results

After KB-1® application, a 10,000-fold increase in Dhc abundance was observed from pre to post bioaugmentation (i.e., from 104 cells/L to 108 cells/L) in less than one year (blue bars on graph). Concentrations of cDCE declined concurrently to below detection limits, reaching regulatory standards (Table 3) in the target monitoring wells for all cVOCs within 1.5 years of bioaugmentation. In 2014 the 95% decrease in cVOC concentrations satisfied the site owner’s remediation objectives.