SITE INFORMATION AND CORRESPONDENCE_1998-2000

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L1LFR LEVINE•FRICKE December 9, 1998 6752.00.050 via fax and regular mail Ms. Wendy Cohen Mr. Kit Custis California Regional Water Quality Control Board _ Central Valley Region 3443 Routier Road, Suite A Sacramento, California 95827-3098 Subject: Report of Phase I IRA Groundwater Treatment System Operational Upset Lincoln Center, Stockton, California Dear Ms. Cohen and Mr. Custis: Levine-Fricke (LFR) has prepared this letter to follow up on our oral communication from December 2, 1998, regarding an operational upset that occurred on November 30, 1998 in connection with the operation of the Phase I IRA groundwater extraction and treatment system (GWETS). The GWETS operates at 6477 Pacific Avenue (rear) in Stockton, California and treats groundwater pursuant to Waste Discharge Requirements (WDR) Order No. 98-062. In accordance with Section B.1 of the standard provisions and reporting requirements of the WDRs, LFR is submitting this report documenting the nature, time, duration and cause of the upset, as well as the measures taken to prevent reoccurrence. The information in this letter is presented chronologically for clarity, although some of the facts were uncovered during the forensic study conducted in the days following the system upset. Time, Duration, Nature and Cause of the Unset The GWETS upset began at 11:04 am on November 30, when the electrical power to the treatment system began to fluctuate, resulting in a low supplied-voltage to the treatment system. Although a rainstorm was underway at the time, it has not been determined whether the storm or some other operational condition related to the power supplier (PG&E) was responsible for these fluctuations. The power fluctuation resulted in the sporadic operation of pump P-2, which empties the air stripper sump. This fluctuation caused the stripper sump to overfill with treated water, which triggered the shutoff to pump P-1. This shutoff caused the surge tank (T-1) to begin to fill with untreated groundwater and rainwater. At 11:24 am, the T-1 high-level alarm was triggered. Although the triggering of this high-level alarm should have cut power to all of the extraction well pumps, this did not happen, and the pumps continued to feed the surge tank. LFR believes that the failure of this interlock was likely caused by the transient power fluctuations that occurred. LFR personnel logged into the system remotely at 1:15 pm, noted the condition of the GWETS, and immediately shut down the system and sent a technician from LFR's Emeryville office to the Site to investigate the problem. 1900 Powell Street, 12th Floor, Emeryville, California 94608-1827 • (510) 652-4500 • fax (510) 652-2246 • www.ifr.com Offices Worldwide