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CASS COUNTY
HOWARD TOWNSHIP
Congressional District # 06
U.S. AVIEX
EPA ID# MID980794556Last Updated: December, 2007
Site Description
The U.S. Aviex site is a six-acre facility, located in the city of Niles, Cass County, Michigan, in a residential neighborhood that primarily includes single family homes. The nearest home is within 100 feet of the facility. Minor agricultural and horticultural activities were performed in the general vicinity of the site.
Historically, the U.S. Aviex Company produced non-lubricating automotive fluids from the early 1960s until late 1978. During operations in the 1960s and 1970s, there were releases of chlorinated hydrocarbons and diethyl ether to the ground water which contaminated private residential wells near the site. A large but unknown amount of chemicals, including trichloroethylene, was also released during a 1978 fire at the plant. These releases impacted the drinking water aquifer in the area. Contaminants were detected in downgradient private residential wells southwest of the plant as far as one-half mile away. The U.S. Aviex facility was added to the National Priorities List on September 8, 1983.
Site Responsibility
This site is a fund financed, State lead Superfund Site.Threats and Contaminants
The ground water and soil are contaminated with volatile organic compounds (VOCs). Direct contact with or ingestion of the contaminated groundwater and soil pose potential health risks. Inhalation of contaminated vapors from the ground water or soil could also potentially cause adverse health effects.Cleanup Progress
U.S. Aviex produced automotive products from the early 1960s to 1978 on a six acre site in Cass County, just south of Niles, Michigan. The products were blends of diethyl ether (DEE) and volatile organic chemicals (VOCs). Large quantities of these chemicals were stored onsite in tanks and the chemicals were piped to the process area. US Aviex became a Superfund Site as a result of two major incidents: (1) a DEE pipeline rupture and (2) a major fire in 1978.
In 1983 Michigan Department of Natural Resources (MDNR) investigations resulted in US Aviex installing a 200 gpm pump and treat system to treat the on-site groundwater contamination. US Aviex operated the pump and treat system for about 10 years. In 1985 a Consent Decree (CD) was signed between US Aviex and U.S.EPA (EPA) to conduct a Remedial Investigation, a study to determine the nature and extent of site contamination and a Feasibility Study, a study of site cleanup alternatives. The Remedial Investigation (RI) was completed in 1986. US Aviex declared bankruptcy and EPA had to complete the Feasibility Study (FS).
The RI delineated two areas in need of cleanup: (1) about 13, 000 cubic yards of VOCs contaminated soils and (2) the contaminated groundwater plume, which extended to Almagus Road, about a third of mile from the facility.
In 1987 MDNR completed construction of a municipal water supply for about 220 homes affected by the contaminated groundwater plume. In 1988 a Record of Decision (ROD), documenting EPA's cleanup plan, was signed. The remedy included:
* A five well extraction system;
* Modification and rehabilitation of the existing air stripper to remove the VOCs;
* Monitoring to ensure effective treatment; and
* Soil flushing by extraction and treatment.
The pump and treat remedy was operated briefly by EPA. In 1993 MDNR assumed the long term response action (LTRA) at the facility. In 1993, studies results showed significant contaminant reduction in the 13,000 cubic yards of soil. A 1993 Explanation of Significant Differences was signed, documenting the decision to eliminate soil flushing treatment. In 1993, contamination was found beyond the capture zone of the installed extraction pump and treat system. An additional purge well was installed in 2000 to prevent further migration of contaminants, which was documented in an ESD.
The pump and treat system was effective in reducing the VOC contaminant concentrations to very low levels. The 2003 quarterly monitoring data indicated that only 1, 2-dichorloethane (DCA) remained present above the maximum contaminant level (MCL) for drinking water, which is 5 ppb. (An MCL is the highest level of a contaminant permitted in a public water supply.) Additional studies conducted by Michigan Department of Environmental Quality (MDEQ) indicated that no contamination was detected in the Niles well protection zones. However, the studies conducted by MDEQ identified two additional small areas of contamination on the US Aviex property. A 100 ft sq of "perched" water table located on the facility, north of the warehouse, contained benzene, trichloroethylene (TCE), 1,2-DCA, and other chemicals at concentrations above the MCLs. Also discovered was an area south of the treatment system which contained tetrachloroethane (PCE), TCE, trichloroethane (TCA), and 1,2-DCA.
MDEQ conducted a pilot study using a BIOX treatment method, which decreased the contamination above the perched water table. The laboratory pilot test suggested that an air/ozone in-situ treatment would effectively reduce the contamination to the south. EPA decided to change the pump and treat remedy to monitored natural attenuation(MNA), augmented with BIOX® treatment for the area near the warehouse, and initiate an ozone/air in-situ treatment of the southern contamination. This decision required a change to the 1988 selected cleanup action, and was documented in a 2004 ROD Amendment. The 2004 Amended ROD included the following six actions:
* Shut down the pump and treat system and rely on MNA to provide for further reduction in contaminant levels in the ground water plume beyond the Aviex facility property line;
* Monitor the natural attenuation of the down gradient contaminants;
* Install and operate an in-situ ozone/oxygen treatment system to assist the MNA;
* Update the ground water clean up standards to the current MCLs standards;
* Use the ozone air sparging treatment for the southern area, to prevent any further off-site migration of contaminated ground water; and
* Provide contingency plan(s) that may include the operation of the existing extraction system with a new air stripper system and/or the installation of a down gradient pump and treat system.
Five-Year Reviews are required whenever waste is left on site above levels that allow for unrestricted use. The first Five-Year Review was conducted in December 2004, and based on site visits conducted from 1999 to August 2004. The technical assessment of the site asked the following three questions:
1. It the remedy functioning as intended by the ROD?....YES
The pump and treat remedy reduced all contaminants of concern (COC) to very low concentrations except for 1, 2-DCA. The other COCs: benzene, chloroform, dichloromethane, ethylbenzene, toluene, xylenes, TCE, TCA, PCE, if present, were at very low concentrations. The 1, 2-DCA above MCLs was located primarily north of the pump and treat capture zone. This chemical is present primarily north of the pump and treat capture zone at concentrations fro 6 to 35 ppb, slightly above the MCL value of 5 ppb. This suggests that the chemical treatment of the perched water table north of the warehouse has eliminated the source of 1, 2-DCA. All current residual 1, 2-DCA should attenuate naturally to below MCL values over the next several years. The ongoing operation and maintenance (O&M) activities at the site still include groundwater monitoring, site maintenance, and enhancements to the MNA, including the ozone sparge and treat system. The MDEQ will maintain the site until the groundwater meets the MCL cleanup criteria.
2. Are the exposure assumptions, toxicity data, clean up levels and remedial action objectives used at the time of the remedy still valid?....YES
MDEQ Part 201 Residential Health-Based Ground Water Criteria reflect concentrations in drinking water which are safe for both long term and daily consumption. The criteria are calculated using currently available chemical-specific data and EPA risk assessment guidance.
3. Has any other information come to light that could call into question the protectiveness of the remedy?....NO
There has been no newly identified human health or ecological risks, impacts from natural disasters, or any other information that has been identified that could affect the protectiveness of the site remedy.
The remedy is currently protective of human health and the environment, and was constructed in accordance with the EPA decision documents. On-site treatment of the perched ground water/soil and the use of in-situ ozone oxidation to address shallow contaminated groundwater augment the current MNA remedy. In order for the remedy to be protective in the long-term, an assessment of the MNA activity must be continued to insure protection of human health and the environment.
The next five-year review is scheduled to be completed by December 5, 2009.
Contacts
Remedial Project Manager, U.S. EPAsheila sullivan (sullivan.sheila@epa.gov)
(312) 886-5251
Community Involvement Coordinator, U.S. EPA
cheryl allen
(312) 353-6196
Aliases
US AVIEX