Soil & Groundwater Investigations
Underground Storage Tanks
Environmental Resources Group, LLC. (ERG) provided compliance services for Venema Services to obtain the closure of a Part 213 leaking underground storage tank (LUST) site (Facility # 00017785) in Zeeland, Michigan. The services provided by ERG include final assessment investigation and reporting, risk based corrective action determination, feasibility analysis, in-situ treatment of impacted soils and groundwater plume via enhanced aerobic microbial biodegradation and dual phase extraction (DPE), an LNAPL assessment, and a vapor intrusion assessment via soil gas sampling.
Excavation and removal of the three USTs began on May 12, 2008. Free product was not encountered at the time of the UST removal. A release (C-0135-08) was confirmed on June 1, 2008, based on the analytical results of the soil samples taken at the time of the UST removals. In addition, two additional USTs were discovered during excavation activities. A registration of Underground Storage Tanks, Amended Information, was filed indicating the status of the discovery.
Following the UST removal, an initial assessment investigation was initiated on-site in May of 2008 and concluded with Final Assessment activities on May of 2009. The overall investigation included completion of 36 soil borings, and the installation of 26 permanent wells. Based on the results of these studies, the soil and groundwater were the only environmental media found to be impacted by the release. Enhanced aerobic microbial biodegradation using RegenOx® and ORC® was selected as the corrective action method to remediate the site. Applications of RegenOx® were injected into the core of the plume to reduce worst case concentrations to promote enhanced biodegradation of the groundwater contaminants present. The RegenOx® applications were performed in October 2010, and July and October 2011. Approximately 3,000 pounds were injected per application as planned.
In an effort to reduce the contaminant level in the core of the plume DPE was conducted on eight wells. The DPE consists of lowering a drop pipe (“stinger”) down the well to the top of the groundwater. The top of the pipe is equipped with a 2-inch rubber gasket that seals the well. By sealing the well, the vacuum placed on the well also recovers vapors from the vadose and smear zone. The vacuum was maintained on each well for a period of eight hours. DPE events were conducted on May 22, 2012 and on July 18 and 19, 2012. A total of 2,000 gallons of impacted groundwater was recovered on May 22, 2012. A total of 1,950 gallons of impacted groundwater was recovered during the July 18 and 19, 2012 DPE event. Following the remedial efforts conducted at the site, ERG completed a total of 31 soil borings on and off-site in an effort to determine the extent of soil impact and determine the extent of residual LNAPL.
The activity on-site continues as presently and ERG is in the process of obtaining restricted covenants for the on and off-site impacted properties to eliminate the remaining risks associated with the release. Once secured, ERG will submit a Restricted Non-residential Closure Report to the MDEQ. Due Care Plans will also be completed for the affected off-site properties.