ARCHIVED REPORTS_XR0010302 - Laserfiche WebLink

Home Browse Search

y .• -REA Working To Restore Nature December 8, 1992 Fire Engine Company No 2, Stockton, California PRESENT GROUND-WATER SAMPLING On October 20, 1992, a technician from RESNA measured the water-levels in wells MW-1 through MW-4 and RW-1 and collected ground-water samples from the wells for subjective and laboratory analyses The field methods and procedures used are presented as an attachment to this report Floating product or product sheen was not noted on samples from the wells Results of subjective analyses are presented in Table 2 Purge water from the wells was stored temporarily in 55-gallon steel drums pending the results of laboratory analyses The City of Stockton is responsible for the disposal of the purge water and has contracted to have purge water removed The tops of the monitoring and recovery wells were surveyed relative to mean sea level on September 9, 1992 We used these data and the water level measurements to evaluate the ground-water flow direction and gradient beneath the site The ground-water gradient was approximately 0 004 with a flow direction to the northeast, as shown on Plate 16 The direction of ground-water flow previously ranged from southeast to northeast with gradients of 0 0028 to 0 033 The elevations of the ground-water surface in each well are shown in Table 1 j Ground-water samples were analyzed for TPHg and total petroleum hydrocarbons as diesel (TPHd) using EPA Method 8015 (modified for gasoline and diesel) and for BTEX using EPA Method 602 These samples were analyzed at RESNA Environmental Laboratories in Fremont, California Copies of the Chain of Custody Records and laboratory analysis reports are attached Results of laboratory analyses indicated that dissolved TPHd was not detected in water sampled from the five wells Dissolved TPHg was detected in ground- water samples collected from wells MW-1 through MW-4 and RW-1 at concentrations ranging from 69 parts per billion (ppb, well MW-3) to 7,200 ppb (well MW-1) Dissolved benzene concentrations in wells MW-1, MW-3, and RW-1 were 590, 27, and 17 ppb, respectively Results of laboratory analyses are summarized in Table 3 WORK IN PROGRESS RESNA performed a pulse test at the site on October 20, 1992, and a pumping test on October 21 and 22, 1992, to obtain hydrogeological data of the water table aquifer and to evaluate the feasibility of removing dissolved hydrocarbons from ground water beneath the site The data from these tests are being evaluated Results of analyses of ground-water samples collected from recovery well RW-1 during the pulse and pumping tests are included in Table 3 1106jese 1 38009-4 3