Blackstone completed a Phase I Environmental Site Assessment (Phase I ESA) of a warehouse facility located on an active Superfund Site in West Des Moines, Iowa. The Site was operated as a steel treatment facility that operated a large degreaser on the Site from 1969 to approximately 2006. Trichloroethene (TCE) was used in the degreaser and was stored in an underground storage tank (UST). The Site is currently occupied by a party equipment and supply company.
Results of soil and groundwater sampling conducted at the Site between 1999 and 2000 identified the former UST operated by the steel treatment facility as the likely source of contamination for the Southern Plume of a larger Superfund Site. Eighteen groundwater wells were installed as part of site characterization and plume delineation activities. Active remediation was performed at the Site from 2005 to 2009 which included the installation of an air sparging system. The Second Five Year Review (FYR) report prepared by The United States Environmental Protection Agency (EPA) in August 2016 indicated that the remedies implemented at Site were functioning as designed and were protective of human health and the environment. The most recent groundwater sampling event indicated that TCE concentrations exceeded the EPA Maximum Contaminant Level (MCL) of 5 micrograms per liter (ug/L) in only four wells, at concentrations up to 16.5 ug/L. Ongoing remedial activities at the site include monitored natural attenuation (MNA) and institutional controls (ICs). The TCE groundwater plume at the Site which is part of the larger Superfund Site was identified as a REC to the subject Site by the Phase I ESA.
Due to large body of prior environmental assessment work on the property, Blackstone did not recommend the performance of a Phase II ESA at this time. However, Blackstone recommended that prior to consideration of potential redevelopment at the Site that a redevelopment driven targeted shallow soil sampling to inform civil design (potable water line construction material in particular), stormwater/soil management, and construction worker health and safety. The results of redevelopment driven assessment of the Site will assist in identifying environmentally conservative measures which may be employed during expansion design such as limiting earthwork in certain areas or the implentation of vapor barriers/controls in new construction.
Blackstone is continuing to work with the client to evaluate other potential environmental concerns in the building including asbestos-containing materials (ACM) and lead paint.