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Proposed Plan for Cleanup of Groundwater

Fact Sheet for Proposed Plan for Cleanup of Groundwater
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Background Document - 2014

FAQs - 2014

Fact Sheet - Jan. 2014

The Administrative Record

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(2007 to present)

NDEP Interim-Action Level

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Maryland Square PCE Plume Map
(JPG - 3rd Quarter, 2012)

History of Monitoring Well Installation

Posters from Community Meeting
(October 26, 2011)

Vapor Intrusion Process

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Maryland Square PCE Site

This webpage provides information about the discovery, subsequent investigation and cleanup of a hazardous substance called tetrachloroethylene [PCE] that was released from the former Al Phillips Cleaners in the Maryland Square Shopping Center at 3661 S. Maryland Parkway.

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The release site is located northwest of the intersection of S. Maryland Parkway and Twain Avenue - Las Vegas Nevada.

The history of site discovery, investigation and cleanup is provided in the Background Document for the Maryland Square PCE site. Additional information is provided in the FAQs and the January, 2014 Fact Sheet.

The following sections describe the cleanup of source area soil at the site of the former dry cleaners and on-going work toward cleanup of the PCE-contaminated groundwater.

Progress on Cleanup, 2011 - 2012

Removal of PCE-contaminated soil at the former Maryland Square Shopping Center — The draft "Corrective Action Plan for Source Area Soil" was submitted to the NDEP on September 13, 2010. Following review and comment by the NDEP, a revised CAP was submitted on December 14, 2010. The NDEP required some additional information, including a schedule for implementation, and concurred with the revised CAP in a letter dated February 25, 2011.

Excavation of source area soil began on August 23, 2011 and was completed on September 19, 2011. Soil samples were collected from the sidewalls and floor of the excavation to confirm the removal of PCE-contaminated soil. Based on these confirmation samples, additional excavation was required on the northern side of the excavation.

The floor of the excavation was treated with an oxidant prior to backfill. The oxidant (potassium permanganate, KMnO4) was applied to further degrade the PCE in groundwater and soil beneath the water table. The excavation was backfilled with clean soil that had been excavated onsite to attain a safe grade on the sidewalls of the pit, as well as clean soil imported from offsite. Backfill and grading of the site was completed in late October, 2011.


Cleanup of Groundwater: Timeline for Pilot Studies and Remedy Selection

The proposed timeline for cleanup of groundwater was provided at the Community Meeting held in Las Vegas on October 26, 2011. Since that time, delays in performing the field tests and pilot studies have modified that schedule. The previous date for completion of pilot studies and submittal of the Corrective Action Report for Groundwater was June 29, 2012. However, drilling for additional characterization did not begin until mid-July, 2012. Data collected from deep drilling and pumping tests called for a reassessment of pilot studies. As of November, 2012, designs for pilot testing were being revisited. Consequently, preparation of the Corrective Action Report, and selection and implementation of the remedy will be delayed while additional site characterization is being conducted. The NDEP will provide a revised timeline for cleanup of groundwater after the Corrective Action Report is submitted by the responsible parties, but a delay of 12 months (from the October 2011 schedule) is not unlikely.

Cleanup of Groundwater: What are the Challenges?

Not all technologies are appropriate for all sites, due to geochemical, hydrological, geological or engineering issues. This is why additional laboratory and field testing are required to determine which technologies are most likely to be effective in cleaning up the groundwater. In the Las Vegas Valley, cleanup of PCE-contaminated groundwater is technically difficult due to the types of geologic deposits and the geochemistry of the shallow groundwater. The remedy must be selected and designed to avoid spreading the plume into areas that are currently unaffected. Ideally, some form of hydraulic containment would be employed to prevent further migration of the PCE mass underneath the residential neighborhood.

Data from the laboratory and field tests will be evaluated, and a preferred remedial technology will be proposed based on criteria outlined in the CAP. The Corrective Action Report will summarize these data and describe the preferred remedy. The NDEP will prepare a "Proposed Plan" summarizing the remedy and requesting public input. All comments and responses on the Proposed Plan will be compiled and provided as an appendix to the Record of Decision (ROD). The ROD is the document that describes the remedy selected to clean up the Site.

After a groundwater treatment system is put in place, groundwater will continue to be monitored on a regular basis. Currently, wells showing a statistical trend of increasing concentration are monitored and sampled every quarter; all other wells are sampled semi-annually or annually. In the future, the frequency of monitoring and sampling may be adjusted to provide adequate data for managing the site, depending on the type of remedy selected and implemented.

Chronology of Actions and Investigations

Additional information on the chronology of the investigation is provided in the Background Document for the Maryland Square PCE Site and in the Administrative Record portion of this website.

Reports and the Administrative Record

Recent reports (from 2007 to 2012) are located here and the entire administrative record, including all reports and correspondence, for the case can be found here. The administrative record is updated as new documents are produced.

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