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 source 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

          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 Activities

         2.1    Operations

2.1.1    Narrative – Situation

     2.1.1.1 Current situation

The Site is a former dry cleaning facility, which has since been turned into a parking lot for an adjacent commercial building. Refer to previous polreps for more detailed site information. 

Highway 6, which runs east-west through Atlantic, Iowa, is adjacent to the Site.  The Iowa Department of Transportation is removing and replacing a portion of Highway 6 from just east of the source area west to Olive Street.  The EPA will be excavating approximately 5 feet of soil from under the highway (after the highway top is removed) adjacent to the source area.  A map showing the excavation area can be found in the document section.           

An Action Memorandum was signed on May 18, 2015. (A copy of the Action Memorandum can be found in the document section.)
  
The removal action will include:

• A removal action at the source area. Any buried drums or tanks will be excavated and disposed. PCE-contaminated soil within the source area will be remediated in situ using electrical resistance heating (ERH), or another variant of in-situ thermal treatment (ISTT).

• Additional soil sampling and analysis under Highway 6 which shows PCE contamination as high as 210 µg/kg in locations adjacent to the Site's source area. The contaminated soil will be excavated to the extent practicable (as agreed on by the EPA and IDOT) in conjunction with IDOT repair work to Highway 6 which is scheduled to be conducted in 2015.

• Additional sampling of groundwater, soil, indoor air and subslab areas at the Site to adequately characterize the source and extent of the plume and the vapor intrusion pathway.

• Additional vapor intrusion sampling and installation of vapor mitigation systems in residential homes, businesses or other occupied structures containing PCE and/or TCE vapor concentrations as warranted. Site-specific action levels were prepared by the EPA's human health risk assessor, to eliminate direct exposure to potentially harmful PCE and/or TCE vapors. If needed, additional systems could be installed in other facilities as well, depending on the lines of evidence.

2.1.2    Response activities to date

HDR, Inc., the IDOT consultant for the construction activities at the Site, is providing oversight of the work.  Scott Nixon with IDOT is in charge of the project.  Bluffs Construction is the IDOT contractor doing the construction at the Site. During the week of June 1, 2015, the Bluffs crew removed the highway top and one foot below the highway top in the area the EPA needs to excavate.    

On June 8, 2015, OSC Fisher and the EPA ERRS contractor mobilized to the Site to begin highway excavation work.  ERRS began excavating on the northeast end of the EPA project area.  A Photoionization Detector (PID) was used to screen excavated soils.  No significant volatile organic compound (VOCs) or odor came from the excavated soil.  ERRS contracted trucks to haul the excavated soil to the staging area, located behind the AMU electric power plant in an open field.  Previously, samples were collected in the staging area to help verify, once the soil is removed, that contamination from the excavation was not left on site. 

On Tuesday June 9, 2015, ERRS continued excavating  and hauling contaminated soil to the staging area.  The excavation area and contaminated soil were screened with a PID with no significant VOC results.  Storm water discharge pipes were exposed on both sides of the excavation; a phone line and abandoned waterline were also exposed.  On Monday and Tuesday a total of 46 truckloads of excavated soil was hauled to the staging area.

ERRS continued excavating and hauling off the excavated soil on Wednesday, June 10, 2015.  Once the excavation was completed, a total of 45 truckloads of excavated soil was removed to the staging area on Wednesday.  The final excavation area is approximately 136 feet x 46 feet x 5 feet.  A map showing the area excavated can be found in the documents section.

Heavy rains occurred overnight.  On Thursday morning, June 11, 2015, approximately three feet of water was in the bottom of the excavation.  It rained all day on Thursday, so the ERRS crew monitored the excavation area and the soil staging area.

On June 12, 2015, it rained most of the morning, resulting in standing water in the excavation area.  The portion of the concrete in the parking lot at the source area where the anomaly was found during the geophysical survey in December 2014 (see geophysical survey report in document section) was removed in preparation for excavation next week.  One ERRS crew member stayed for the weekend to monitor the site; all other crew members, as well as OSC Fisher, mobilized from the site.

On Monday, June 15, 2015, OSC Fisher and the ERRS crew mobilized to the Site.  Over the weekend it rained every day.  The excavation area still had standing water.  AMU loaned ERRS a trash pump to remove the water from the excavation.  Water was pumped from the excavation into the city sewer lines.

The area where the anomaly was found in the parking lot was excavated.  The excavation extended approximately 20 feet x 5 feet x 5 feet (pictures of the excavation can be found in the documents section).  In the anomaly area an abandoned 2-inch pipe was found.  The pipe came from the direction of the commercial building then turned north toward the highway.  The pipe was located approximately 3.5 fbg.  At the elbow of the pipe where it turned north was a sandy area that is not native to the other soil in the excavation, which indicates the sand was used as fill.  The sandy fill was followed south as well; nothing was found in the disturbed soil.  It appears that the 2-inch pipe was the anomaly. Because the pipe turned north underneath the plant bed, the geophysical survey did not pick up the pipe going to the west to the commercial building, thus making it look like there was an underground storage tank or buried drum in that area.  (Pictures of the 2-inch pipe can be found in the document section.)  ERRS filled in the excavated area with limestone rock.  OSC Fisher discussed the excavation area with the bank, and for the time being the concrete will not be replaced because of future planned removal activities at the Site.

On Tuesday, June 16, 2015, the excavated area was drying out.  ERRS brought in ground up rock with lime dust from a local quarry and spread the material out over the west end of the excavation.  This helped solidify the base of the excavation to allow backfilling to begin.  All water was removed from the excavation with the trash pump.

On Wednesday, June 17, 2015, ERRS began backfilling the west end of the excavation.  The portion of the highway removal not in the contaminated area had previously been sampled by the EPA.  That soil was excavated by Bluffs Construction during highway removal activities.  ERRS used this soil as backfill in the excavation area.  The HDR supervisor came by the site and approved the excavation area to begin backfilling. The backfill was rollered-in.  The excavation was completely backfilled by the end of the day.  The HDR supervisor approved the area.  Soil samples were collected from the excavated soil pile and sent to an off-site lab.

June 18 - 23, 2015 - waiting on analytical results from the excavated soil.

June 24 - 27, 2015 - ERRS removed the excavated soil from the staging area to the Pheasant Point Landfill, which is acceptable for the receipt of CERCLA off-site materials.  Pheasant Point Landfill is owned by Waste Management and is located in Omaha, Nebraska.  Approximately 1,630 tons of soil was taken to the landfill.        

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

2.2.2 Issues

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

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              microgram per kilogram
µg/m³             microgram 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