7th Avenue and Bethany Home Road Water Quality Assurance Revolving Fund

Site

August 20, 2013

Site History

• The property was originally developed in 1952 as a small shopping center. The shopping center included a market, a variety of small businesses and a dry cleaner.

• The dry cleaner leased the space and began operations in 1953 and until 1960 the shopping center was connected to an on-site septic system.

• The site was originally investigated by the property owner between 1995 and 2001. Investigations confirmed the presence of tetrachloroethene (PCE) in the soil and groundwater beneath the site. In 2000, the septic tanks and associated piping were removed.

Site History

•In October 2004 ADEQ, and their contractor conducted a Early Response Action (ERA) evaluation of the property. It was determined that Soil Vapor Extraction (SVE) was a viable remedial measure to reduce the source of contamination at the site.

•ADEQ and the property owner, Bayless Investment and Trading Company, entered into a consent decree in April 2005. ADEQ received a settlement in the amount of $225,000. The decree indicated the property owner had already spent approximately $170,000 investigating and remediating the site.

Site History

• The SVE system operated from June 2005 until January 2006. Approximately 380 pounds of volatile organic compounds (VOCs) were removed from the site and reduced concentrations of PCE in the soil vapor at the site from over 2,500 parts per billion (ppb) to less than 150 ppb.

• Soil sampling confirmed the remaining soil concentrations are below residential soil remediation level of 0.51mg/kg and groundwater protection levels of 1.3 mg/kg.

Site History

Site History

• In 2008 ADEQ completed an additional ERA evaluation of another dry cleaner, located across 7 Avenue from the site.

• Investigations at the second drycleaner indicated that the remaining concentrations of PCE in the soils at the property are not present above regulatory standards, but the groundwater is impacted with PCE concentrations ranging from 8 to 22 μg/l, above the Aquifer Water Quality standard ( AWQS) of 5 μg/l.

• In January 2009, ADEQ initiated Remedial Investigation activities at the site.

Site History

• Final Remedial Investigation Report completed in April 2011 included the Remedial Objectives (ROs) for the site.

• Based upon review of public comment, the ROs are based on the following:

• Protect against possible leaching of hazardous substances from the upper portion of the aquifer into deeper portions of the aquifer where groundwater use is occurring.

Remedial Objectives Review

• Ground water sampling in January 2012 indicated a significant increase of PCE concentrations in the wells at both properties.

• Increasing water table elevations are suspected of mobilizing additional contaminants from the soils to the groundwater.

• Data received from Salt River Project indicated their well, located approximately one-half mile north of the source area, has been impacted above the AWQS of 5 parts per billion.

January 2012 Groundwater Monitoring Results

7th Avenue and Bethany Home Road Site Map

North-South Geologic Cross Section

2012 Groundwater Monitoring Results

January 2012 Groundwater Monitoring Results

January 2012 Groundwater Monitoring Results

SRP Well 10.1N-13.5E Historical PCE Results

• Feasibility Study (FS) completed November 2012. Due to increases of PCE concentrations at the site, the FS evaluated three methods to reduce concentrations in the groundwater at the source area.

1. Enhanced reductive dechlorination (ERD)2. In situ chemical oxidation (ISCO) 3. Groundwater Extraction and Treatment (GWET)

Feasibility Study

Feasibility Study Cost Comparison

• Based on the cost and other factors, ERD was selected for the pilot test at the site. ERD is preferred over the similarly priced GWET because it has the ability to destroy the volatile organic compounds in place and the potential to be completed in a quicker time frame.

Feasibility Study

2013 New Wells & Select April

2013 Data

PCE 28TCE ND

PCE 120TCE ND

PCE 13TCE 18

PCE 1400TCE 3.2

PCE NDTCE ND

PCE 1.8TCE ND

PCE 410TCE 1.1

PCE 28TCE ND

Pilot Test

GW Flow Direction

MW-14

MW-3R

Pilot Test

IW-1DIW-1S

MW-3RMW-3

Pilot Test

IW-1DIW-1S

MW-3RMW-3

5/3/13 – Tracer at End of Injection 6/28/13 – Tracer at Most Recent Sampling

Questions?

Questions

Contact Information

Scott Goodwin, Project ManagerRemedial Projects Sectionsdg@azdeq.gov(602) 771-4452, 1-800-234-5677 ext 771-4452

Wendy Flood, Community Involvement CoordinatorRemedial Projects Sectionwv1@azdeq.gov(602) 771-4410, 1-800-234-5677 ext 771-4410

Contact info