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 (ATSDR), 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 one home, and received laboratory results for sampling conducted in February and March.  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 or crawl space of eight homes.  Concentrations in those homes ranged from 2.3 to 152 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 five homes at concentrations ranging from 1.5 to 20 µg/m³.  The VISL for PCE in indoor air is 110 µg/m³.
• Trichloroethene (TCE) was detected in the sub-slab or crawl space of one home at a concentration of 47.1 µg/m³.  The VISL for TCE in sub-slab is 70 µg/m³.
• TCE was found in the duplicate sample of indoor air at one home.  However, TCE was not detected in the original sample.  EPA resampled the home and TCE was not detected.  
• cis-1,2-Dichloroethene (cis-1,2-DCE) was detected in the sub-slab of one home at a concentration of 7.7 µg/m³.  cis-1,2-DCE has no VISL.
• cis-1,2-DCE was detected in the indoor air of two homes at concentrations of 4.8 and 23.1 µg/m³3.
•  Vinyl chloride was detected in the indoor air of one home at a concentration of 0.99 µg/m³.  The VISL for vinyl chloride in indoor air is 1.7 µg/m³.

EPA is planning to resample four homes in August 2016.  Indoor air concentrations increased in three of those homes.  The fourth home previously had high levels of TCE in indoor air.  EPA sealed the basement sump and TCE concentrations subsequently decreased.  However, EPA wants to ensure that TCE does not rebound and present a threat to public health.

EPA also completed plumbing connections and removal of bladder tanks in all homes, except two.

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 following sections discuss planned response activities and next steps.

2.2.1.1 Planned Response Activities
In August 2016, EPA will resample four homes for vapor intrusion.

2.2.1.2 Next Steps
See above.

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.