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EnvIronmental lt 101'1� ADea `�i Seta rCG Saeratrecrc.r A 95670 consultants,enc. 916 n24 2435 PAX 3'5 6'e•3285 Navvmber 7, 1991 Mr. Glenn R. Dernbroff Ultramar Inc. 525 West Third Street 1larrFord,California 93230 Subject: Quarterly Monitoring Report, 'bird Quarter 1991 Beacon Station No.6.45 900 South Cherokee Lane, Lodi,California Delta Project No. 40-91-831 Dear Mr. Dembroff: Delta Euvironmentzi Consultants, Inc. (Delta), has been authorized by Ultramar Inc. (Liltramar), to t conduct a hydrogeologic investigation at Beacon station No. 695 lom2ed at Sop Soudt Cherokee Lane, i San Joaquin County,Lodi,California(Figures I and 2). The purpose of this l,'Westigadon is to monitor the ground water Ieveis and the distribution of petroleum hydrocarbon co nstlt3rents in the ground water beneath the site. This Ietter report contains the results of the quarterly ground water monitoring and sampling Performed at the site an September 20, 1991, Fiell work conducted at the site by Delta was performed in accordance with the field methods and procedures described in Enclosure A. A total of 23 ground water monitoring wells are present at the site. Monitoring wells PrflV-1$,AZVt+-24, 141W-27 and recovery well RW--1,contaii-ted measurable ground water on September 20, 1991 Crible 1). Ground water was not present in the remaining monitoring wells at the site. Ground water was present at the site between approximately 68 and 71 feet blow the surxce, Ground water elevation contours based on the September 20, 1991, data are illustrated in Figure,3. These contours indicate the ground v<ate� flaw direction is toward the southeast (figure 3), ,,avith an averat;t hydraulic gradient of approximately O,Qg6-foot per foot. Ground water level data collected from each monitoring well at the site since January 1988 is presented in Enclosure B. Ground water samples collected on September 20, 1991, were submitted to a California-cerdfled laboratory for analysis of benzene, toluene, ethylbenzene, and xylenes (BTE}) and total petroleum hydrocarbons(TPH)as gasoline. A summary of ground water sample analydcaI resttJts is presented in Table 2. A dissolved benzene concentration:map based on the September 1941 ground water sample analytical resalts is illustrated in Figure 4. A summary of ground water analytical results for sr mples collected at the site since 1985 is presented in Enclosure C. Copies of the field sampling irtforfn les sheets are presentee{ in Enclosure D. Copies of the September I es ground water sampleforini reports are Presented in Enclosure E. --- laboratory --. -- ---_ - --_, t j 1, Delta Celivers 5olunons