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Brown and Caldwell Consultants 23SStreet Sacramento aiirornia 95814 7092 1 p�# 1 3.61 444 )123 93 211" 16 I-t I I: 5 h 1916! 44.8437 June 14, 1993 Mr Chuck Carmel ARCO Products Company Post Office Box 5811 San Mateo, California 94402 017-7403-01/1 Subject Second Quarter 1993 Report for ARCO Station 2093, 3425 Tracy Boulevard, Tracy, California: Pilot Program Site 1416 . Dear Mr Carmel- This report presents water level,measurr4nents and results of groundwater sampling performed during the second quarter of 1993 at ARCO Products Company (ARCO) Station 2093,located at 3425 T,a,N Boulevard in Tracy, California. Fieldwork was performed by Emcon Associates un �►pnl 14 and 15, 1993. This report was prepared under 'Task Order 2093-93-5 There are sCven on-site wells (ATR-1 through ATR-7) and five off-site wells,(ATR-8 through 00 ATR-12), as shown on Figure 1. Six of the on-site wells and all of the off-site wells were sampled. One on-site well (ATR-3) was not sampled because it contained`floating product. Field and Analytical Methods Emcon Associates personnel measured depth-to-water and product thickness (if present), purged each well to be sampled, and collected groundwater samples at the site. Depth-to- water measurement and a check for floating product were made prior to commencing purging Prior to sampling, the wells were purged of a minimum of three well volumes or until evacuated using a centrifugal pump or bailer. After purging, each well was sampled using a Teflon bailer. All groundwater samples were analyzed for total petroleum hydrocarbons,as gasoline (TPH-G), and for benzene, ethylbenzene, toluene, and xylenes (BM) by U.S. Environmental Protection Agency (EPA) Method 5030/8020/Dl4S LUFT. Field data sheets and the chain-of-custody form are included in Exhibit A. ; Results The general groundwater flow beneath the Site on April 14, 1993, was to the east-northeast under an average hydfttilic gradient of 0.003 (Figure 3). A summary of depth-to-water measurements and calculated groundwater elevations is presented in Table,l. Table 2 lists past and presdnt groundwater flow directions and hydraulic gradients for this site. Thts report was prepared to acc6h&nce with the standards of the envtronttttntal consulting industry at the time it was prepared It 40 should not be relied upon by parties other than those for whom it was prepared,and then only to the extent of the scope of work which was authorized This report does not guarantee thet any additional environmental conditions beyond that described to this report exist at this site 74034ZEP0RTSAM93QTR RPT