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DEER <br /> LEVINE•FRICKE <br /> February 17, 1999 6752.00-100 <br /> via fax and U.S. mail <br /> Ms. Wendy Cohen <br /> Ms. Wendy Wyels <br /> California Regional Water Quality Control Board <br /> Central Valley Region <br /> 3443 Routier Road, Suite A <br /> Sacramento, California 95827-3098 <br /> Subject: Phase I Interim Remedial Action Groundwater Extraction Well Upset, Lincoln Center, <br /> Stockton, California <br /> Dear Ms. Cohen and Ms. Wyels: <br /> LFR Levine-Fricke (LFR) has prepared this letter to follow up on our oral communication of <br /> February 11, 1999, regarding an operational upset to the Phase I IRA groundwater extraction well <br /> GEW-16 at Lincoln Center in Stockton, California. The Phase I IRA Groundwater Extraction and <br /> Treatment System(GWETS) extracts groundwater along Pacific Avenue at Lincoln Center and <br /> treats the extracted groundwater at 6477 Pacific Avenue (rear) in Stockton, California. The <br /> extracted groundwater is treated pursuant to Waste Discharge Requirements (WDRs) Order No. 98- <br /> 062. In accordance with Section B.1 of the standard provisions and reporting requirements of the <br /> WDRs, LFR is submitting this report documenting the nature, time, duration, and cause of the <br /> upset, as well as the measures taken to prevent reoccurrence. <br /> Based on LFR's review of the pump operation data for well GEW-16, it appears that the extraction <br /> well upset began at approximately 6:00 a.m. on February 9, 1999, when the GWETS was returned <br /> to service following a shut down for maintenance on pump P-2. At 8:00 a.m. on the following day <br /> (February 10, 1999), while surveying activities were being conducted in connection with the <br /> remedial investigation, LFR personnel observed water being released from the seam in the well <br /> vault cover of GEW-16. LFR field personnel immediately notified LFR office personnel of the <br /> condition and well GEW-16 was remotely shut down. Upon investigation it was determined that a <br /> check valve located at extraction well GEW-16 failed, thereby causing water being extracted from <br /> well GEW-16 to be released into the well vault from two approximately 1/4-inch-diameter holes <br /> where the holding pin for the check valve had broken. Because of the nature of the water spraying <br /> slightly sideways into the vault from the two holes, water was also being partially sprayed from one <br /> of holding pin holes through the overhead seam in the vault cover to a grass-covered area <br /> surrounding the vault. LFR personnel observed water draining from the well vault across the grass <br /> and the adjacent sidewalk and into the gutter along the western side of Pacific Avenue. LFR's <br /> evaluation indicates that, although no definitive cause of the failure was identified, the most likely <br /> cause of the valve failure was the very cold weather conditions that at the time. These conditions <br /> may have caused the flapper gate within the check valve to freeze during the maintenance of pump <br /> 1900 Powell Street, 12th Floor, Emeryville, California 94608-1827 • (510) 652-4500 • fax (510) 652-2246 • www.Ifr.com <br /> Offices Worldwide <br />