1.1.1    Incident Category

CERCLA incident category: Inactive Production Facility

1.1.2  Site Description

1.1.2.1 Site Location

The Site is located at, and in the area of, 1205 East 7^th Street, Atlantic, Cass County, Iowa. The approximate coordinates of the Site are latitude 41.403718° north and longitude 94.995763° west. The Site is a former dry cleaning facility, which has since been turned into a parking lot for an adjacent commercial building. 

The City of Atlantic has a population of 7,008 (U.S. Census Bureau 2012) and is located in Cass County, Iowa, approximately 45 miles northeast of Council Bluffs and 75 miles west of Des Moines. Land use in the area of the Site is a mixture of commercial and residential. The City of Atlantic Municipal Utility well field is located adjacent to Troublesome Creek. 

1.1.2.2 Description of Threat

Analytical results from samples collected by the U.S. Environmental Protection Agency indicate that hazardous substances have been released into the environment at the Site.  Tetrachloroethene (PCE) and its degradation products are hazardous substances as defined in CERCLA section 101(14), 42 U.S.C. § 9601(14), and as designated in 40 CFR § 302.4. PCE and trichloroethene (TCE) have been detected in soil, groundwater, subslab, and indoor air samples at levels that exceed the EPA's removal action levels (RALs) and screening levels.  Site screening and RALs for indoor air and subslab soil vapor can be found in the action memorandum, a copy of which is located in the document section.

Concentrations of PCE as high as 3,400,000 micrograms per kilogram (µg/kg) have been found in soil at the source area. Concentrations of PCE as high as 260 micrograms per liter (µg/L) have been found in groundwater at the Site. Subslab soil vapor concentrations of PCE detected at a nearby business were as high as 2,261 micrograms per cubic meter (µg/m³). Screening levels for subslab soil vapor for a business are 1,800 µg/m³. The owners of the business with subslab soil vapor concentrations above the screening level have voluntarily installed a vapor mitigation system. 

Vapor intrusion occurs when vapors emanating from contaminated soil and/or groundwater migrate through the vadose zone into overlying structures and into the indoor air. When chemicals are spilled on the ground, they frequently seep into the soil and make their way into the groundwater. Volatile organic compounds (VOCs), including PCE and TCE, produce vapors that travel through soil. These vapors can enter buildings through cracks in the foundation, or a basement with a dirt floor or concrete slab or crawl space.

PCE is a man-made chemical that is widely used for dry cleaning clothes and for metal degreasing. It evaporates easily into the air and has a sharp, sweet odor. Exposure to PCE vapors at very high concentrations (particularly in closed, poorly ventilated areas) can cause dizziness, headaches, drowsiness, confusion, nausea, difficulty in speaking and walking, unconsciousness, and death. PCE has been shown to cause liver tumors in mice and kidney tumors in rats. It has been determined that PCE is a Class 2A carcinogen via inhalation based on long-term exposure.

TCE is defined as a hazardous substance in section 101(14) of CERCLA, and is designated as a hazardous substance in 40 C.F.R. § 302.4. The Agency for Toxic Substances and Disease Registry (ATSDR) reports that inhalation exposure to TCE at very high concentrations may affect the central nervous system, with symptoms such as dizziness, headaches, confusion, euphoria, facial numbness, and weakness. Recent studies have linked TCE with fetal structural heart malformations associated with exposure during the prenatal period. 
 
1.1.3     Removal Preliminary Assessment/Removal Site Inspection Results

Concentrations of PCE-contaminated soil as high as 3,400,000 µg/kg have been found at the Site.  The contamination in the soil has leached to the groundwater, and has impacted the City of Atlantic’s (City) well field located approximately 1 mile downgradient of the Site.   The City’s municipal water supply well field, which supplies the City’s drinking water, has been impacted by PCE at concentrations exceeding the EPA maximum contaminant level (MCL) for PCE.  Concentrations of PCE as high as 260 µg/L have been found in these municipal wells. Lesser concentrations of breakdown products such as trichloroethene (TCE) and 1,2-dichloroethene (DCE) have been reported sporadically in one or more wells. One of Atlantic Municipal Utilities (AMU) city water wells (AMU-7) has been disconnected from the system and is currently being pumped continually to the City public-owned treatment works (POTW) to provide hydraulic control and protect the nine other municipal wells from contamination.  However, AMU-7 has deteriorated over time; the gravel pack is falling into the well, and the pump has had to be replaced twice.  At this time, AMU-7 is no longer providing hydraulic control of the PCE contamination.  AMU-6 is located downgradient of AMU-7 and is now showing PCE contamination as high as 17 µg/L.  All the City’s well water is dumped into the clear well before it is distributed into the drinking water system.  The clear well is sampled monthly for PCE and TCE contamination. 

At the source, which was formerly occupied by a dry cleaners and an Iowa Department of Transportation (IDOT) materials testing laboratory, approximately 40 feet of silts and clays overlie the fine- to coarse-grained friable Dakota sandstone. The silt and clay soils at the source have been contaminated with PCE at depths too deep for physical removal or conventional remediation. Currently a parking lot and commercial building reside where the dry cleaning and material testing lab used to be. Based on data collected, it appears that PCE contamination at the source continues to vertically migrate down into the Dakota sandstone aquifer and travel horizontally to the City’s municipal well field.  The EPA has collected indoor air and subslab samples in the businesses and homes adjacent to and nearby the source area, as well as downgradient of the source area.  Subslab sample results were as high as 2,261 µg/m³.  Indoor air sample results were found at concentrations of 76 µg/m³.  The subslab sample results were above EPA screening levels at one business.  The owner of the business has voluntarily installed a vapor mitigation system inside the business. 

The groundwater flows north-northwest from the source area toward the municipal well field, and the plume of contamination follows the groundwater gradient.

2.0    Current Activities2.1    Operations

2.1.1    Narrative – Situation

2.1.1.1 Current situation

An Action Memorandum was signed on May 15, 2015.  A removal action was started on May 26, 2015.  The removal action will address imminent substantial threats to human health and the environment. Currently an additional municipal well (AMU-6) is being threatened with PCE contamination.  A removal action in the form of thermal technology is being planned to address the source area.  Addressing the source area will remove any additional contamination contributing to the groundwater plume, however the contamination left in the groundwater will need to be addressed as well.  

A long-term response action will be needed to address the groundwater contamination.  In order for this to happen the site needs to be placed on the National Priorities List.

2.1.2    Response activities to date

2.1.3    Enforcement Activities, Identity of Potentially Responsible Parties (PRPs)

2.1.4    Progress Metrics

No information available at this time.

AMU            Atlantic Municipal Utilities

ATSDR        Agency for Toxic Substance Disease Registry

CFR             code of federal registration

CERCLA      Comprehensive Environmental Response, Compensation, and Liability Act of 1980

DCE             dichloroethene

EC                electric conductivity
EPA             Environmental Protection Agency

ERRS           Emergency and Rapid Response Services

ERT              Environmental Response Team

fbgs              feet below grade surface

HRS             Hazard Ranking Score

IDNR            Iowa Department of Natural Resources

IDOT            Iowa Department of Transportation

MCL             Maximum Contaminate Level

MIP              membrane interface probe

MW              monitoring well
NPL              National Priorities List
OSC             On Scene Coordinator

PCE             Tetrachloroethene

PDB             passive diffusion bags

PID               photoionization detector

POTW          Public Owned Treatment Works

ppm              parts per million

PRB              Permeable Reactive Barrier

PRP              Potential Responsible Party

RAL               removal action level

REAC            Response Engineering and Analytical Contract

SB                 soil boring

START          Superfund Technical Assessment & Response Team

TCE              Trichloroethene

TOC              total organic carbon

µg/L               Micrograms per Liter
µg/kg             micrograms per kilogram
µg/m³            micrograms per cubic meter
VOCs            volatile organic compounds

PCE (Tetrachloroethene):           

•       A man-made chemical that is widely used for dry cleaning clothes.

•       It evaporates easily into the air.

•       A colorless liquid with a mild, chloroform-like odor - has a sharp, sweet odor.

TCE (Trichloroethene):

•       Used to remove grease from fabricated metal parts and in the production of some textiles.

•       PCE degrades to TCE under certain circumstances.

•       A colorless or blue liquid with a chloroform-like odor - has a sharp, sweet odor

For more information about these chemicals go to: http://water.epa.gov/drink/contaminants/basicinformation