1.1.1 Incident Category
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Incident Category:  Groundwater plume site 

1.1.2 Site Description
The following sections provide information on the site location, description of threat, and removal assessment results.

1.1.2.1 Location
The site is a Residential Area bounded by West Vermont Street to the south, Holt Road to the east, West Michigan Street to the north, and North Rybolt Avenue to the west in Indianapolis, Marion County, Indiana.  The site consists of 23 homes that rely upon private drinking water wells as their only sources of water. 

1.1.2.2 Description of Threat
In 2009, the Marion County Public Health Department (MCPHD) identified homes in the West Vermont-Cossell Road neighborhood that obtained drinking water from private wells.  MCPHD sampled the wells and detected vinyl chloride in drinking water at three residences at concentrations above the Removal Management Level (RML) (January 2015) of 1.9 micrograms per liter (µg/L) and Maximum Contaminant Level (MCL) of 2 µg/L in groundwater used as a drinking water source 

Vinyl chloride is a hazardous substance, as defined by section 101(14) of CERCLA.   According to the Agency for Toxic Substances and Disease Registry, the effects of drinking high levels of vinyl chloride are unknown.  However, the U.S. Department of Health and Human Services has determined that vinyl chloride is a known carcinogen.  In addition to ingestion of contaminated water, there is potential exposure via inhalation of vinyl chloride vapors from  use of contaminated water for cooking, showering, and bathing.  Breathing vinyl chloride for long periods of time can result in permanent liver damage, immune reactions, nerve damage, and liver cancer.

1.1.3 Preliminary Removal Assessment/Removal Site Inspection Results
See previous Pollution Reports (PolRep).

On May 1, 2015, the U.S. Environmental Protection Agency (EPA) approved an action memorandum to conduct a time-critical removal action to connect residential properties to a municipal drinking water supply; properly abandon private drinking water wells; conduct sub-slab and indoor air sampling at residential properties; perform vapor mitigation, as necessary; and transport and dispose off-site any hazardous substances, pollutants and contaminants at a CERCLA-approved disposal facility in accordance with U.S. EPA's Off-Site Rule (40 Code of Federal Regulations [CFR] § 300.440).

2.1.2 Response Actions to Date
During the reporting period, EPA conducted sampling for vapor intrusion at three homes.  A summary of those results is below.  EPA compared results to Vapor Intrusion Screening Levels (VISL) using a Target Risk for Carcinogens of 1x10^-5 and a Target Hazard Quotient (THQ) for Non-Carcinogens of 3, except for TCE, which had a THQ of 1.  

• Tetrachloroethene (PCE) was found in the sub-slab the three homes sampled.  Concentrations in those homes ranged from 49 to 600 micrograms per cubic meter (µg/m³).  The VISL for PCE in sub-slab is 3,600 µg/m³.
• PCE was detected in the indoor air of the three homes sampled at concentrations ranging from 0.59 to 57 µg/m³.  The VISL for PCE in indoor air is 110 µg/m³.
• Vinyl chloride was detected in the indoor air of one home at a concentration of 2.6 µg/m³.  The VISL for vinyl chloride in indoor air is 1.7 µg/m³.

Volatile organic compounds (VOC) were detected below the VISL in the indoor air of two homes.  After three sampling events, EPA determined that those homes did not meet the requirements of a complete vapor intrusion pathway.  

Vinyl chloride was above the VISL in the indoor air at one home, although PCE was below the VISL in indoor air.  Both PCE and vinyl chloride were higher in the indoor air sample than the sub-slab sample. Vapor intrusion follows gas diffusion characteristics, where the vapors move from areas of higher concentration to lower concentration. Therefore, the sub-slab concentration should be higher than the indoor concentration.  The home had many chemical containers that could not be removed during the sampling event; as such, elevated VOC concentrations in indoor air are likely due to indoor air sources. EPA concluded that the home did not meet the requirements of a complete vapor intrusion pathway after three sampling events.

2.1.3 Enforcement Activities, Identity of Potentially Responsible Parties (PRPs)
Enforcement strategies are contained in a confidential Enforcement Addendum to the Action Memorandum.

2.1.4 Progress Metrics
Progress metrics include waste generated during assessment activities and previous removal actions.

2.2.1 Anticipated Activities
The site was placed on the National Priorities List (NPL) in September 2016.  Additional activities will be conducted by EPA's remedial program.

2.2.1.1 Planned Response Activities
Not applicable (NA)

2.2.1.2 Next Steps
NA

2.2.2 Issues
None.

* The above accounting of expenditures is an estimate based on figures known to the OSC at the time this report was written. The OSC does not necessarily receive specific figures on final payments made to any contractor(s). Other financial data which the OSC must rely upon may not be entirely up-to-date. The cost accounting provided in this report does not necessarily represent an exact monetary figure which the government may include in any claim for cost recovery.