Congressional District # 11
HI-MILL MANUFACTURING CO.EPA ID# MID005341714
Last Updated: November, 2014
The Hi-Mill Manufacturing Company (Hi-Mill) Superfund Site, 4.5 acres in size, is a former industrial site located in Highland Township, Oakland County, Michigan. Hi-Mill Manufacturing, the Potentially Responsible Party (PRP), began manufacturing tubular aluminum, brass, copper tubing, and other parts in 1946. From 1946 until the mid-1980s, process wastewater that contained residues of acids and heavy metals was periodically emptied into lagoons on the site. Prompted by complaints from Hi-Mill employees, the Michigan Department of Natural Resources (MDNR) sampled the two onsite production wells and an adjacent pond (referred to as “Target Pond”) in 1972. One well was contaminated with a volatile organic compound (VOC), and Target Pond was found to be contaminated with metals.
Although the shallow groundwater beneath the Hi-Mill property and nearby areas is contaminated, it cannot be used as a drinking water source now or in the future due to its low water yield. The last time the intermediate aquifer, which is a drinking water source, showed a trace amount of trichloroethylene (TCE) was in a groundwater sample collected in April 1998. Since then, TCE has not been detected in any of the intermediate well samples. The nearest homes are approximately 2,000 feet southeast of the site.
On February 21, 1990, the U.S. Environmental Protection Agency (EPA) placed the Hi-Mill site on the National Priorities List (NPL).
This site remedy was being addressed through PRP actions under a federal enforcement agreement, with support from the Michigan Department of Environmental Quality (MDEQ). Currently, Hi-Mill Manufacturing is no longer in business at the site. EPA is working with MDEQ to ensure that long-term groundwater monitoring continues at the site.
Threats and Contaminants
Shallow groundwater beneath the Hi-Mill property and Highland Road (northwest of the site) is contaminated with VOCs, including TCE, 1,2-dichloroethylene (1,2-DCE), and vinyl chloride. Surface and subsurface onsite soils are contaminated with organic and inorganic compounds. Sediment and surface water in Waterbury Lake (south of the site) and Target Pond contain elevated concentrations of heavy metals but do not appear to be adversely impacted.
Deed restrictions prohibit the use of groudwater from the shallow groundwater unit, so there is no current health risk from exposure to contaminated groundwater.
In November 1983, under State of Michigan supervision, Hi-Mill cleaned up the on-site lagoons by removing 142 cubic yards of contaminated soil, 34,400 gallons of contaminated sludge, and 63,300 gallons of contaminated water. The lagoons were backfilled with clean sand. However, the results from the 1988 resampling of two onsite production wells revealed high levels of TCE and 1,2-DCE. In 1989, a new well was installed to provide Hi-Mill employees with safe drinking water.
Between 1989 and 1992, Hi-Mill conducted a Remedial Investigation (RI), which is a study to determine the nature and extent of site contamination, and a Feasibility Study (FS), which is an analysis of site cleanup alternatives. These studies were performed as part of an Administrative Order on Consent (AOC) signed in October 1988. Shallow groundwater beneath the Hi-Mill property and nearby areas was found to be contaminated with TCE, 1,2-DCE, and vinyl chloride. The primary sources of the organic contamination were believed to be the accidental release of solvents from solvent delivery lines and leaks from several former and current solvent storage tanks. However, the intermediate aquifer showed no sign of contamination. Sampling results from the surface and subsurface soil, sediment, and surface water from the nearby pond and lake revealed elevated concentrations of heavy metals at some locations, but the water bodies did not appear to be significantly impacted by the contamination. The source of the heavy metals was believed to be the former on-site lagoon area.
Based on the results of the RI/FS, EPA issued a Record of Decision (ROD) on September 28, 1993. The ROD selected a cleanup plan for the site. The ROD requires 30 years of groundwater monitoring and the implementation of institutional controls (ICs) to prevent use of the shallow groundwater beneath the Hi-Mill property. A federal Consent Decree, whereby the PRP agreed to implement the remedy, was entered on December 7, 1994.
ICs that restrict the use of groundwater on the Hi-Mill property were put in place on December 22, 1994. Installation of six shallow monitoring wells and two intermediate monitoring wells was completed in September 1995, and quarterly monitoring of groundwater began in October 1995. Between October 1995 and July 2000, groundwater samples from between 19 and 23 monitoring wells were collected four times per year. (Note: The number of samples has varied due to freezing in some wells during winter months, lack of groundwater in some wells during dry summer months, and installation of several new wells at the site.)
According to a provision in the ROD, the PRP had the option of petitioning EPA for a reduction in groundwater monitoring requirements after three years of monitoring. In July 2000, EPA approved the PRP's request for a reduction. Since October 2000, two wells were sampled quarterly, three wells were sampled biannually, and an additional 18 wells were sampled annually. As a result of the Second Five-Year Review performed at the site in 2005, three additional monitoring wells were installed in the intermediate aquifer to provide for better monitoring of the groundwater conditions at the site.
EPA completed the Third Five-Year Review for the site on September 27, 2010. The review found that the remedy is protective of human health and the environment. The review recommended that the groundwater monitoring program at the site be revisited and that a revised sampling regimen implemented that includes the newly-installed intermediate monitoring wells. EPA and MDEQ also recommended that two community wells west of the site be monitored to ensure that the Wellhead Protection Area located downgradient is not impacted by the site. The five-year review also recommended that the ICs required at the site be evaluated and that an IC plan be developed to ensure long-term protectiveness of the remedy. The next five year review will be completed by summer 2015.
In August 2014 the Hi-Mill property was sold at auction by the County. EPA has been in communication with the new owner, who is conducting an environmental assessment of the property and is aware of the existing deed restrictions. EPA is working with the MDEQ to develop a revised sampling plan for the site, as well as to evaluate what future actions, if any, are warranted at the site.
ContactsRemedial Project Manager, U.S. EPA
linda kern (firstname.lastname@example.org)
Community Involvement Coordinator, U.S. EPA
AliasesHI-MILL MFG CO