Beginning in 2020, GZA GeoEnvironmental, Inc. worked closely with IKI Manufacturing, Inc. (IKI) and the law offices of Axley Brynelson, LLP to complete regulatory reporting and site investigation activities, evaluate remaining contaminant mass, retardation and advective flow, and the protection of human health and the environment. The Wisconsin Department of Natural Resources (WDNR) issued regulatory closure on September 13, 2023. This important milestone completed 30 years of environmental and regulatory obligations and facilitated the investment of new processing lines at IKI.
Investigations into this former industrial and boat manufacturing site began in 1993 with the evaluation of soil, groundwater, surface water, and vapor. Among the contaminants of concern were petroleum volatile organic compounds (VOCs), chlorinated VOCs, and chlorofluorocarbons. The site had three aquifer profiles, including an upper sand aquifer and lower sand aquifer, which were connected, and a bedrock aquifer. The Site also contained a man-made pond, which was fed by groundwater and located in an historical area where solvents were burned.
Three different consultants were engaged on the site, and in 2020, GZA was retained to consolidate 27 years of data and develop a complete understanding of site conditions, aquifer quality, and natural attenuation conditions of the dissolved VOC plume to communicate to the WDNR.
GZA conducted sampling of the on-site pond and groundwater to evaluate the dissolved plume conditions. Vapor sampling was also conducted at select on-site and off-site buildings as part of the site investigation requirements under Wisconsin Administrative Code NR 716. In addition to the site investigation work and reporting, GZA assessed the performance of remedial activities consisting of in-situ carbon solution injection to determine the mass of VOCs biologically degraded through reductive dichlorination, and the remaining mass of residual VOCs in soil and groundwater at the site.
GZA conducted statistical analysis of the groundwater data, including contaminant retardation and advective flow. The observed extent of the dissolved plume was confirmed at distances on-site significantly less than the predicted extent, based on adsorption and biologically mediated conditions.
GZA provided regulatory communications to the WDNR during the site investigation and remedial performance process. GZA also developed and provided the requisite supplemental site data to allow the WDNR to fully understand the improved Site conditions following the remedial activities.
Further data collection found that the upper sand aquifer saw a contaminant reduction of approximately 97% while the mass of hydrocarbons in the lower sand aquifer was reduced by 99%. Since GZA began work at the Site in 2020, GZA was able to get an approved Site Investigation Report in April 2021, and then proceeded to receive Site Closure from the WDNR in September 2023.