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Chemical injection to address Polynuclear aromatic hydrocarbon (PAH) contamination in the soil and groundwater within the area of a former heating oil UST behind the 2414B 10th Avenue tenant space (location of monitoring well MW-4) was approved by the WDNR in a letter dated June 27, 2018. No chemical injection was proposed for the area around MW-3 (southern extent of the site), where only groundwater monitoring is being performed.
The chemical injection around the former heating oil UST was performed on July 19, 2018, and follow-up groundwater sampling was performed on July 30, 2018. Post-injection confirmation soil sampling was performed on August 2, 2018.
A discharge monitoring report was submitted on August 13, 2018, as required under WPDES permit WI-0046566-07. The NR 140 Exemption Post-Injection Report, dated September 18, 2018, included a summary of the pilot-scale injection information collected during injection activities.
The post-injection/third quarter groundwater sampling results were provided in the Quarterly Groundwater Sampling Report dated August 17, 2018. The fourth quarter groundwater sampling was performed in October 11, 2018, and the results were provided in the Quarterly Groundwater Sampling Report dated October 29, 2018. The groundwater concentrations in MW-4 for the third quarter showed no detectable concentrations of PAH constituents above the Preventative Action Limits, so no further chemical injection in the area around MW-4 was proposed in the Design Report Addendum/Remedial Action Plan (RAP) dated October 18, 2018. However, continued quarterly sampling of MW-4 was proposed in the RAP as a result of a minor concentration rebound observed in the fourth quarter groundwater sampling. Continued quarterly sampling of MW-3 was also proposed to establish any trends in groundwater concentrations. The RAP was approved by WDNR in a letter dated December 19, 2018. The next quarterly sampling event is scheduled to be completed in January 2019.
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