ARCHIVED REPORTS_XR0012699 - Laserfiche WebLink

Home Browse Search

Procedure)". Selected samples will be delivered under Chain of Custody Procedures to Pacific Environmental Laboratory in San Francisco, aState-certified laboratory, for analysis. After sampling, the soil borings will be backfilled with a cement/bentonite slu rry using the tremle pipe method. To minimize the potential for cross-contamination, augers and associated equipment'Will be steam cleaned with a high pressure washer prior to drilling each boring. The sampling equipment and brass tubes will be cleaned with an Alconox or trisodium phosphate wash and rinsed with distilled water prior to collecting each soil sample. . f ualitative Field Screenin To provide a preliminary indication of possible hydrocarbon ccntamination, a portable organic vapor detector will be used to monitor for the presence of organic vapors in soil collected from the borings. This field screening method consists of filling a glass jar to about one third capacity with soil and sealing the container with an air-tight lid. After approximately 15 minutes a hole is punched in the lid of the container and a probe attached to an organic vapor analyzer (OVA) equipped with a flame ionization detector (FID) is inserted In the headspace of the container. The concentration of organic:vapors in the headspace, In parts per million by volume, is then read and noted on the boring logs. Field screening will also include visual observation of samples to note changes in color or appearance which hydrocarbons, might suggest the presence or absence of petroleum f LABORATORY ANALYSES soil s---am�es Two samples will be selected from each of the four soil borings (for a total of 8 soil samples) for laboratory analysis. The two samples from each boring will be selected based on the results of field screening and stratigraphic location. The sample with the highest value from the organic vapor screening and the deepest sample collected will be submitted for analysis. The soil samples will be analyzed for total petroleum hydrocarbons(TPH)as gasoline and for benzene, ethylbenzene, toluene and xylenes (l3ETX). Lead will not be analyzed for In the samples due to the low lead concentrations (10 mglKg) reported in the sample colle^ted from the tank excavation, where lead concentrations would be expected to be i highest. If a Waste Extraction Test(WET) were performed.on this sample, and all of the lead In the sample Wbs soluble, the concentration of the lead In the extract would be I mg/L, which Is below the 5 mg/L STLC for lead, Since the lead concentrations in the soil are e;,pected to decrease with depth, analyses for lead have not been Included In the A - 3 }