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Pacific Southwest, Region 9: Superfund

Serving Arizona, California, Hawaii, Nevada, the Pacific Islands, and Tribal Nations

Alark Hard Chrome

EPA #: CAD098229214

State: California(CA)

County: Riverside County

City: Riverside

Congressional District: 43

Other Names:

Bulletin Board

On 10/13/17, this website will no longer be updated. Site information will be migrated to the new web page at: http://www.epa.gov/superfund/alarkhardchrome .
EPA appreciates your patience through this transition. If you have questions, please contact EPA staff listed below.


Description and History

NPL Listing History

NPL Status: Final

Proposed Date: 07/27/00

Final Date: 12/01/00

Deleted Date:

Alark Hard Chrome was a plating operation located on Main Street near Poplar Street in Riverside, CA. It operated from 1971 until it was closed in 1985. In 1982, the Riverside County Health Department inspected the site and discovered soil contamination. The Alark Potentially Responsible Parties (PRPs) were ordered to investigate the full extent of contamination at the site. All plating equipment and indoor storage tanks were removed from the site when the Riverside County District Attorney Office permanently closed Alark's operations in 1985. During the 1980's, the Alark PRPs conducted investigations, and in 1986 began an unauthorized removal of soil which was stopped by the California Department of Toxic Substances Control (DTSC). In 1990, DTSC took over the site investigation, splitting their efforts into a soils component and a groundwater component. In December 2000, the Alark facility was placed on the U.S. Environmental Protection Agency's (EPA) Superfund National Priorities List.

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Contaminants and Risks

Contaminated Media
  • Groundwater
  • Soil and Sludges

Soil and groundwater were contaminated with chromium, hexavalent chromium, other metals and TCE as a result of spills, drips and discharges of plating solutions to a sump on the premises.

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Who is Involved

This is a fund-lead site. EPA is the lead agency.

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Investigation and Cleanup Activities

Site Studies

Between 1991 and 1995, DTSC installed ten groundwater monitoring wells in the vicinity of the Alark facility to monitor groundwater contaminated by chromium. In 1994, DTSC excavated and removed approximately 1,200 cubic yards of the most heavily contaminated soils from the middle of the Alark facility and closed off the site. This area was also the main source of groundwater contamination, but significant soil contamination remains on the site.

In 2001, EPA conducted groundwater sampling and the results were consistent with the groundwater investigation conducted by DTSC in 1995. There were still high chromium concentrations in monitoring wells closest to the site. In one well (MW-7), the groundwater sample contained 17,300 micrograms per liter (ug/L) hexavalent chromium. Chromium exceeded the State Maximum Contaminant Level (MCL) for drinking water of 50 ug/L in five of the ten wells at the site. Since 2001, EPA has been conducting a remedial investigation to determine the extent of soil and groundwater contamination at the site. The remedial investigation has been difficult due to the complex fractured bedrock geology in the area. In August 2007, EPA completed the field work for the remedial investigation with the installation of one additional monitoring well that defined the groundwater contaminant plume southeast of the site. This completed definition of the groundwater contaminant plume in all directions. The RI Report was completed in December 2009.

In October 2007, EPA began a Treatability Study to evaluate the effectiveness of in-situ treatment of hexavalent chromium (Cr+6) in the vadose zone and groundwater at the Alark Site. The in-situ treatment method selected uses a calcium polysulfide solution to reduce the Cr+6 to trivalent chromium (Cr+3). Cr+3 is much less toxic that Cr+6 and is also much less soluble in groundwater. Cr+3 is stable in the soil and will not convert back to Cr+6 in the normal soil environment. The Treatability Study was completed in December 2007 and a final Treatability Study Report issued in April 2009.

EPA has completed field work and will conduct a Feasibility Study for possible cleanup alternatives once funding has been obtained.

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Cleanup Results to Date

The site has been closed. EPA has completed an initial remedial investigation to define the full extent of contamination. EPA will begin looking at possible ways to clean up the soil and groundwater contamination as part of the Feasibility Study when funding becomes available.

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Potentially Responsible Parties

Potentially responsible parties (PRPs) refers to companies that are potentially responsible for generating, transporting, or disposing of the hazardous waste found at the site.

No viable parties have been identified to date.

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Documents and Reports

Show details for Fact SheetsFact Sheets
Show details for MapsMaps

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Community Involvement

Public Meetings:

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Public Information Repositories

The public information repositories for the site are at the following locations:

Riverside Public Library
3581 Mission Inn Avenue
Riverside, CA 92501
(909) 826-5201

The most complete collection of documents is the official EPA site file, maintained at the following location:

Superfund Records Center

Mail Stop SFD-7C

95 Hawthorne Street, Room 403

San Francisco, CA 94105

(415) 820-4700

Enter main lobby of 75 Hawthorne street, go to 4th floor of South Wing Annex.

Additional Links

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EPA Site Manager
Rusty Harris-Bishop
US EPA Region 9
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Community Involvement Coordinator
Carlin Hafiz
US EPA Region 9
Mail Code SFD
75 Hawthorne Street
San Francisco, CA 94105
EPA Public Information Center
State Contact
Joe Cully
California Department of Toxic Substances Control
5796 Corporate Ave.
Cypress, CA 90630
PRP Contact
Community Contact
Other Contacts
After Hours (Emergency Response)
(800) 424-8802

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