ARCHIVED REPORTS XR0001826 - Laserfiche WebLink

Home Browse Search

December 22, 1998 Harding Lawson AssOciStOs 4034405 ' Margaret Lagorio, Supervising RENS San Joaquin County Public Health Services Environmental Health Division ' Page 4 The borings were logged by a California iegisteied geologist The soils were visually classified using the Unified Soil Classification System (USCS), soil classifications, PID readings, and other field observations were recorded on standard HLA field logging forms The borings were tremi-grouted to surface grade with a slurry of neat cement in accordance with PHS/EHD requirements on the day they were drilled PHS/EHD was notified in writing at least 48 hours prior to the grouting process to allow adequate time to 1 schedule PHS/EHD staff to observe the grouting process Hydropunch Groundwater Sampling A Hydropunch groundwater sample was collected lust below where groundwater first encountered in boring S13-1 which was drilled adjacent to the former source of petroleum hydrocarbons Groundwater was first observed in the soil sample collected from SB-1 at a depth of 20 0 to 20 5 feet bgs Prior to driving the Hydiopunch sampler, the depth to watei had risen to a static level of approximately 16 feet bgs The groundwater sample was collected with the following Hydropunch sampling techniques After removing the solid-stem auger from the borehole, a Hydropunch sampler was driven and pushed 3 5 feet beyond the bottom of the borehole to a depth of 24 0 feet bgs A disposable drive point with an attached 5-foot long PVC screen remained at this depth as the outer part of the sampler was lifted up 2 5 feet to expose the screen A stainless-steel bailer was lowered down the drive rods connected to the sampler and used to collect formation water that entered the exposed Hydropunch screen The groundwater sample was immediately capped, labeled, and placed in an ice-chilled cooler for transport to a state-certified analytical laboratory The sample was recorded on a chain-of-custody form to document sample identification and handling Analytical Program A total of six soil samples and one Hydropunch gioundwater sample were analyzed for TPHd and TPH as motor oil (TPHmo) with Environmental Protection Agency (EPA) Method 8015M, and for BTEX with EPA Method 8020 In addition, soluble data were collected from the sample which contained the maximum detected concentrations of petroleum hydrocarbons Soil sample (SB-1-10) was analyzed for soluble TPHd and TPHmo using the Waste Extraction Test (WET) procedure with deionized water and for soluble BTEX using the Toxicity Characteristic Leaching Procedure (TCLP) with deiomzed water and the zero headspace method In addition, the same sample was analyzed for polycyclic aromatic hydrocarbons (PAHs) using EPA Method 8270 Insitu Bioremediation Feasibility Studies Because insitu passive bioremediation is the prefeired (most cost effective) iemedial alteinative for low- risk petroleum hydrocaibon UST sites, analytical data was collected that assess the efficacy of passive bioremediation as a viable alternative for the site Plate counts of the total indigenous heterotrophic microbial population and the subset of hydrocaibon utilizers were performed on two samples at the HLA's 1 bioremediation laboratory in Novato, California The purpose of the plate counts was to demonstrate the appropriate range of cell densities for insitu bioremediation One sample (SB-1-5 0) contained TPH- impacted soil and one sample (SB-2-5 0) was representative of non-impacted soils These samples were collected at similar depths and in similar soil types In addition, soil sample SB-1-5 0 was analyzed for total organic carbon, water content,bulk density, and porosity, soil sample SB-2-5 0 was also analyzed for total organic carbon