1.1.2 Site Description

The Armentrout Excavation Landfill (AEL) Site is located at 766 Hawkins Road in Xenia, Greene County, Ohio.  The former AEL occupies approximately 8.25 acres and is surrounded by residential properties and farmland.  The extent of the Site, including residential properties, is approximately100 acres.

Access to the former landfill is through a 2-acre property containing two buildings that were originally part of the landfill but that are now privately owned by a nearby resident.  The landfill is covered with soil and overgrown with vegetation.  Two structures for storing materials are located within the landfill.  These structures are surrounded by various types of debris, including compressed gas cylinders, tires, and construction materials. 

The landfill is on top of a steep hill.  Within 0.5 miles of the landfill are 28 residences.  Five of these residences are located within 500 feet of the former landfill.

1.1.2.1 Location

The site is located at 66 Hawkins Road in Xenia, Greene County, Ohio. The Site's geographical coordinates are 39° 25' 17.9106" North latitude and 83° 35'23.5164" West Longitude

According to the Ohio Environmental Protection Agency’s (Ohio EPA) Armentrout Removal Action Referral Form dated February 11, 2010, Frank L. Armentrout, now deceased, purchased the former AEL in 1934.  The AEL operated as a sand and gravel excavation pit beginning in 1944.  Mining operations ended in 1971,when the gravel pit became a licensed landfill.  During its operation as a sand and gravel pit, sand and gravel were mined from the upper 60 feet.  Mining reportedly ceased when an underlying clay layer was encountered.  However, unauthorized waste dumping reportedly occurred at the gravel pit before 1971.  Authorized filling by the Carboline Company began as early as 1957.

Records indicate that from 1957 to 1979, paint-related wastes, organics, inorganics, solvents, and metals were disposed of at the AEL.  The paint-related wastes contained lead, chromium, cadmium, barium pigments, and aluminum flakes.

From 1971 to 1980, AEL operated as a regulated and licensed disposal facility and received construction debris and selected industrial wastes.  AEL was approved for the disposal of dry, nonhazardous industrial wastes, demolition material, wastes from PDI Plastics Company, and solid wastes from the Moran Paint Company.

The AEL was closed in January 1980 after the Ohio EPA and the Greene County Health Department discovered that the landfill had accepted unapproved domestic and commercial wastes.  In 1981, the landfill was completely filled and covered with 2 feet of clay soil. 

On April 8 and 9, 2002, the Ohio EPA conducted the first supplemental environmental site investigation (SESI) at the Site.  The SESI included the sampling of monitoring wells on the AEL property and surrounding residential wells.  The Central Regional Laboratory (CRL) analyzed water samples from 14 residential wells and 6 AEL monitoring wells for Target Analyte List (TAL) metals, sulfate, chloride, ammonia nitrogen, and nitrate-nitrite.  Five of the residential wells contained arsenic at concentrations exceeding the arsenic maximum contaminant level (MCL) of 10 micrograms per liter (µg/L).  The highest arsenic concentration detected in a residential well was 70.8 µg/L.  

In October 2009, the Ohio EPA conducted a second SESI under an agreement with the U.S. EPA.  This SESI focused on documenting releases of arsenic in residential wells and determining if the AEL was responsible for the elevated arsenic concentrations observed in residential well samples.  The Ohio EPA collected samples from 37 wells in the Site area, including 6 AEL monitoring wells, 24 residential wells, 4 Greene County wells, and 3 commercial wells.  The CRL analyzed the samples for antimony, arsenic, barium, beryllium, cadmium, chromium, cobalt, copper, lead, manganese, nickel, selenium, silver, thallium, vanadium, zinc, aluminum, iron, potassium, sodium, fluoride, chloride, sulfate, bromide, ammonia, nitrate, and nitrite.  Seven of the samples from residential wells contained arsenic at concentrations exceeding the MCL of 10 µg/L.  Two additional wells contained arsenic at concentrations approaching the MCL.  The highest arsenic concentration of 50.9 µg/L was detected in a residential well. 

1.1.3 Preliminary Removal Assessment/Removal Site Inspection Results

On March 12, 2010, U.S. EPA met with the property owners of the 10 residential properties identified for sampling and obtained signed access agreement from each property owner granting permission to U.S. EPA to access the property in order to conduct sampling.  All of the property owners signed an access agreement.

On April 7, 2010, U.S. EPA conducted a site assessment at the AEL Site and collected 13 samples from the 10 residential properties.  Ten groundwater samples were collected before any filtration or treatment system, if present.  Arsenic was detected in 11 of the 13 samples at concentrations ranging from 6.09 to 49.4 µg/L resulting in seven locations with arsenic concentrations exceeding the established action level of 10 µg/L.  In addition, arsenic was detected at a concentration near the established action level at one residential location.  Sampling conducted at this location by Ohio EPA in October 2009 indicated an arsenic concentration exceeding the established action level.

In addition to field sampling, an evaluation and summation of all previous and current analytical and hydrogeological information available for the Site and surrounding area was performed in a technical memorandum to EPA concluding that the landfill was the source of arsenic contamination in nearby residential drinking wells.

Based on site assessment sample analytical results, the Site meets three criteria for a removal action pursuant to 40 CFR 300.415(b)(2).