Response Activities
The DNRE and the Environmental Protection Agency (EPA) have been conducting soil and groundwater investigations and response activities at the Property from 2003 to the present. In 2002/2003, at the request of the DNRE, the EPA removed all the containers of chemicals and waste that were left behind and fenced a portion of the site.
In 2003, the DNRE performed an electromagnetic survey and test pitting to find buried metal objects (e.g. drums, underground storage tanks), 100 soil borings up to 95 feet in depth to determine the extent of soil and groundwater contamination, dust and concrete floor sampling to determine the extent of contamination in the building materials, the onsite injection well abandoned and installed 15 monitoring wells to monitor groundwater contamination.
In 2004, the DNRE performed aquifer testing to determine aquifer conditions at the site, Perry Creek surface water flow and groundwater plume discharge evaluation to determine whether the groundwater contamination is discharging completely to Perry Creek, pore water sampling in Perry Creek to determine the extent of the discharge area of the groundwater contamination and biannual sampling of the existing monitoring well network and Perry Creek to monitor the contamination.
In 2005, the DNRE conducted 190 soil borings and collected 1,700 soil samples to determine the extent of soil contamination, additional soil borings to 150’ below grade to determine the vertical extent of the groundwater contamination, additional pore water sampling to refine the extent of the plume discharge area in Perry Creek and determine if the floodplain east of Perry Creek has been impacted, installed 11 additional monitoring wells to monitor groundwater contamination and biannual sampling of the well network and Perry Creek to monitor the contamination.
In 2006, the DNRE performed a geophysical investigation to identify potential conductive contaminants in the groundwater and clay surfaces with estimated thicknesses, additional borings up to 430 feet in depth to determine if underlying groundwater aquifers have been contaminated, additional pore water sampling in Perry Creek and the surrounding floodplain to determine the extent of the groundwater contamination on the East side of the creek, installed 6 additional monitor wells to monitor groundwater contamination and biannual sampling of the monitoring well network and Perry Creek to monitor the contamination
In March 2006, the USEPA installed a security fence around the entire building and access drive to the site to prevent unauthorized access. In May 2006, the EPA removed approximately 9,500 tons of contaminated soil and buried sludge from the site. In July 2006, the EPA cleaned the interior of the on-site buildings to facilitate demolition. The equipment and scrap metal were cleaned and placed outside the building for disposal, the free dust was vacuumed, interior surfaces pressure washed, and all remaining hazardous debris, sludge and wastewater were disposed of from the building.
Demolition of the former Hoskins Manufacturing buildings in 2007 In 2007, the DNRE conducted the demolition of the former Hoskins Manufacturing buildings, excavation and disposal of 1,400 tons of additional contaminated soil from pickling line area after demolition, macroinvertebrate study at Perry Creek to determine whether the aquatic community has been impacted by the discharge of the contaminated groundwater to the creek, sampling of sediment in Perry Creek to determine the extent of contamination and conduct toxicity testing and performed biannual groundwater and surface water sampling in the network of monitoring wells to monitor the groundwater contamination.
View of metal contaminated soil during the excavation in 2008 The DNRE in 2008, performed additional deep and shallow groundwater investigation to fully define and verify the extent of groundwater contamination in the three aquifers. More soil sampling was performed to fully define the horizontal extent of the soil contamination at the site in preparation for the feasibility study. Thirteen monitoring wells were installed in the deep and shallow aquifers.
IIn May 2008, 21 permanent sampling points were installed in the floodplain surrounding Perry Creek in the area where the groundwater is discharging to the creek. In October 2008, six more permanent sampling points were installed in and around Perry Creek. The Perry Creek sampling points will be sampled biannually with the monitoring wells.
DNRE-WB staff shocking fish on Perry Creek for fish study in 2009 From the fall of 2003 through 2010, groundwater sampling in the onsite monitoring wells has been and will be performed biannually to monitor the status of the groundwater contamination. A feasibility study was completed in 2010 is which various cleanup methods were analyzed to determine the cleanup methods that are likely to be the most effective based on site conditions. The results of the feasibility study indicated that the most technically feasible and cost effective method of remediation at the site is recirculating enhanced reductive dechlorination (ERD).
ERD is a cleanup technique that involves the injection of an extremely biodegradable carbon source (ethyl lactate) into the groundwater, which changes conditions in the groundwater. The altered conditions are conducive to naturally occurring bacteria that break down chlorinated solvents, like PCE into harmless byproducts. The same carbon source also creates groundwater conditions that are conducive to a chemical change of hexavalent chromium, to the less toxic trivalent chromium and cause chromium to precipitate out of the groundwater. A full scale remedial effort would be comprised of three pumping wells above the bluff to capture the groundwater contamination prior to discharging to Perry Creek. The contaminated groundwater would be pumped back to the source area and multiple injection zones, amended with the ERD carbon source and re-injected back into the plume area. A portion of the amended water would also be introduced in shallow zones at the site in the source soil areas, allowing the accelerated mobilization of contaminants into the groundwater. Current funding through the State of Michigan is not sufficient to allow for full scale remediation.
A small scale remedial action is being conducted in 2010 and 2011 which involves injection of a carbon source in a smaller area of groundwater with higher concentrations of contaminants at the site. This limited cleanup is anticipated to remediate a localized mass of impacted groundwater and the data from will be used to evaluate on a small scale the effectiveness of the proposed alternative from the feasibility study. Installation of additional injection wells and monitoring wells for the small scale remediation was completed in May 2010. A tracer test was conducted to verify groundwater velocity and to provide additional information for the implementation of the groundwater injection. Injection of the carbon source was initiated in July 2010.
A fish study in the plume discharge area of Perry Creek was completed by the DNRE. Fish from Perry Creek, both at the discharge area and downstream, and from a nearby creek for comparison were collected. Both the fillets and the livers from the brown trout were analyzed for chromium. Chromium was not detected except in three samples. Two fillet samples and one liver sample from Perry Creek had small detections of chromium concentrations. No samples from West Branch Big Creek had total chromium. All detections of chromium in the fish however were below the preliminary screening levels, and advisories of consumption of fish are not necessary.
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