ARCHIVED REPORTS XR0012758 - Laserfiche WebLink

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,Ma ........... W I-XFClUTIVF SUNVNIAR_y SSB Environmental Consultants, Inc.,was autilorizcd by Thrifty Oil Company to evaluate the presence round water at Thrifty oil Company Station No.172 iocated of gasoline range hydrocarbons in soil and g at 7647 Pacific Avenue in Stockton. California. During this investigation four 8-inch outside diameter (O.D.)soil borings were advanced to a depth of 76 to 80 feet below site grade. soil samples were obtained at 5 foot intervals from each of the four soil borings to a depth of 55 to 60 feet. Each sample was field analyzed for Petroleum hydrocarbons using y six soil samples from each boring were submitted to a State each a phOLOionization detector. Approximately TU ea boring was certified laboratory for analysis of selected gasoline constituents. One sample from analyzed for total lead. One sample from boring B-2 was analyzed for gasoline range aromatic compounds and selected metals using TCLP extraction methods. -water monitoring well was constructed in each boring. Each monitoring well ..k 2-inch diametcr ground collected from each well and analyzed for was developed and purged. Ground-water Samples Were concentrations of BTEX and TPHg,and total and fecal coliform in wells located within 50 f.et of sewer lines. The soil profile beneath the site consists of black, organic sandy clay to a depth of 5 feet below site grade. Fine to medium grained, brown, silty sands were encountered from 15 to 20 feet. Fine to medium grained, silty sands and low plasticity sandy silts, were encountered from 20 to 60 feet. Fine 10 medium grained,reddish-brown,poorly graded sands were encountered at a depth of 60 feet,at which depth ground water was cnroun(crcd and below which no additional soil samples were collected. The results of analyses indicate that the highest concentrations of gasoline range petroleum hydrocarbons in soil were found between the depths of 20 and 45 feet in boring B-2. The highest concentrations detected in boring B-1 were substantially lower than those detected in boring B-2. Only trace concentrations were detected in borings B-3 and B-4. The concentrations of compounds detected in soil in borings B-3 and B-4 are likely due to the lateral migration of fuel constituents an historically shallower ground-water levels. Gasoline range organics were not detected in the sample from boring B-2 analyzed by TCLP extraction methods. The concentration of barium detected by the same procedure does not exceed regulatory levels. Detected corcentrations of total lead do not exceed current regulatory levels. The results of the chemical analyses indicate concentrations of purgeable and base, neutral and acid collected from all four wells. The highest concentrations of compounds and the compounds in samples c were indicated by analysis of the ground-water sample from highest number of detected compounds affected by gasoline range petroleum hydrocarbons. MW-2. Results indicate that ground-water has been a nearby sewer line has affected ground water The results also indicate that a waste stream leaking from beneath the site.