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yA�f 1117 Lone Palm Avenue, Suite 201B <br /> �� Cardno tY Modesto, California 95351 <br /> ATC '.01 f 209-579-2221 <br /> ,tX}. Fax:209-579-2222 <br /> Shaping the Future y <br /> `�V' � � �'`��'^ \R !^�- ,Uw�+r+ r"1 •�\awn] <br /> Once purging is com 1 Sum canistelr, fitted with a 200 ml/miinnrut_e flow restrictor,will be �' <br /> connected to th va or a as; nd samples collected. Prior to sampling, a leak ec <br /> compound derived from commercial computer"dusi-off' spray (such as 1,1-Difluoroethane (1,1 DFA], <br /> or similar) will be applied to rags and used monitor leaks wi m t e above ground vapor probe <br /> assembly. The "dust-off' spray will be sprayed into a plastic bag containing several cotton cloth rags. <br /> The rags will be placed adjacent to, but not touching, each portion owe sample appayants, inc <br /> the area where the Teflon tubing exits the ground. O ILLS+ <br /> /Upon completive vapor probes will be removed and the borings will be backfilled/grouted with <br /> J neat Portland cement from the boring terminus to ground surface. }y <br /> � 5L�v <br /> Sam le Anal sis l r,� . F fJ� k}IJ+ ' v"� <br /> Soil vapor samples collected fr the soitv <br /> orbes will be im diat' ely transferred under chain-of- <br /> orcustod rocedures to ons to State-certEacH soil vapor sample will be analyzed <br /> mg EPA Method TO-1 ch soil vapor samp a will also be analyzed for the leak check compound ✓ <br /> wd a me o etection limit of less than10 l. E ample will be screened at the laToratory to <br /> evaluate for elevated concentrations. A Me o 8260B ay be employed for some samples to �f <br /> prevent an elevated dilution factor, which would affect the detection limits£sort' f the compounds. <br /> For Quality Assurance/Quality Control purposes, a minimum of one duplicate sam ill be collected <br /> � <br /> properly labeled and submitted under chain-of-custody Lard ocedur s l va r provided by <br /> immediate) after the original sample from a selected vapor robe location„ e <br /> the analytical laboratory will be analyzed for target compounds Each soil vapor sample will be <br /> qV ,�-11owP�R'�P 5 " i- Ek. sva <br /> P P Y YP Vuu-bc ,w+ <br /> -r .tQglank- Iiutdi�t.cxt ;A 14Y I, b,anl( * 10b` I <br /> YN`W� Risk Assessment q -5i tl C+�P l n <br /> A tiered evaluation will be conducted using the laboratory analytical data. The scil mor data will be <br /> compared to the values listed in Table 2 of the Tier_1 ESLs as published by the San Francisco Bay <br /> Regional Water Quality Control Board (SF RWQCB) in November 2007 and the California Human <br /> Health Screening Levels (CHHSLs) published by the California Environmental Protection Agency <br /> (CAL EPA) in January 2005. If any of the analytes of interest exceed the ESLs and/or CHHSLs, these <br /> analytes will be evaluated utilizing the Tier 2 Modeling program. Cardno ATC will use the Johnson <br /> and Ettinger Vapor Intrusion_Model for Soil Vapor Emissions to Indoor Air Risk Assessment as <br /> appropriate for Residential Exposure Scenario for High Permeability (Sandy) Soils, version 1.0 (2005). <br /> Analytes of intem9 detected above laboratory method detection limits from vapor sampling will be <br /> inputted into the model to evaluate the Hazard Quotient for carcinogens and non-carcinogens. For the <br /> purpose of this indoor air risk assessment, Cardno ATC will assume the hypothetical building at risk is - 7 <br /> slab on grade. Cardno ATC will compare Hazard Quotient Ratios to conservative and action levels <br /> establish""ei�y the SF RWQCB and evaluate if additional sampling and/or modeling is necessary. <br /> Report Preparation <br /> S:T6MVeportsWa ar-2015 SUISWPd= 5 Cardno ATC <br />