ARCHIVED REPORTS_XR0004671 - Laserfiche WebLink

Home Browse Search

Quarterly Groundwater Monitoring Report No 2 February 9, 1998 ' On October 8 and 9 1997 fourgroundwater/air co-extraction wells X-1 EX-2 EX-3 and EX- 4)were installed at the site The details of this activity were reported in our report entitled "Co- Extraction Well Installation Report," VRC-Manteca, 151 South Main Street, Manteca, California, dated November 4, 1997 1 On December 8, 1997, a 250 gallon underground storage tank(UST) discovered at the site was removed The details of this activity were discussed in our report entitled"Underground Storage ' Tank Removal," OST Project Number 701-12,Former Diamond Lumber Site, 151 South Main Street, Manteca, California, dated December 31, 1997 Although we were told that we would ' receive a tank closure letter from San Joaquin County Public Health Services after the tank was removed, in spite of several requests,we have not yet received this closure letter Also completed during this time period was the installation of the underground piping and initial set up of the soil vapor and groundwater remediation system Final set up and start up of this system is anticipated to take place during the first quarter of 1998 40 RESULTS ' The results of the laboratory analyses of the groundwater samples and the water level ' measurements are discussed in the following sections 4.1 Analytical Results Elevated concentrations of TPHg and BTEX in some samples interferred with EPA Method 8020 MTBE analyses for those samples This interference resulted in lugh dilution factors which ' raised the detection limits This interference was not experienced with the EPA Method 8260 oxygenate analyses for MTBE which resulted in consistently low detection limits For this reason, MTBE concentrations reported from the EPA Method 8260 oxygenate analyses were rused in the tables ' The laboratory analytical results indicated that the gasoline related compounds were not detected in the groundwater samples collected from monitoring wells SRK-MW1 and SRK-MW3 In addition,the compounds MTBE,DIPS,ETBE and TAME were not detected in the samples from ' any of the monitoring wells The compound TBA was only detected in monitoring wells, SRK- MW2 and BEI-MW-3 at concentrations of only 40 parts per billion (ppb) and 24 ppb, respectively Laboratory results indicated TPHg concentrations below 500.ppb in monitoring ' wells MW-7 and MW-8 at concentrations of 490 and 200 ppb, respectively, with BTEX concentrations ranging from < 0 5 ppb to 32 ppb Laboratory results also indicated TPHg ' concentrations in excess of 1,000 ppb in monitoring wells BEI-MWl and BEI-MW2 at concentrations of 3,800 ppb and 5,400 ppb, respectively, with BTEX concentrations ranging ' OST 701 1-2 qm2 Page 3