Laserfiche WebLink
PUBLIC HEALTH SERVICES <br /> SAN JOAQUIN COUNTY <br /> JOGI KHANNA M.D..M.P.H. <br /> Health OfficerP <br /> P.O. Box 2009 • (1601 East Hazelton Avenue) 0 Stockton, Califomia 95201 F o a <br /> (209)468-3400 <br /> CLINT ROGERScc <br /> ' <br /> CHEVRON USA lJ <br /> P O BOX 5004 <br /> SAN RAMON CA 94583-0804 OCT 0 1 1992 <br /> Re: Chevron Station #9-6171 SITE CODE: 1784 <br /> 6633 Pacific Avenue <br /> Stockton CA 95207 <br /> San Joaquin County Public Health Services, Environmental Health Division (PHS/EHD) <br /> staff conducted a site inspection on September 3, 1992 the purpose of which was to <br /> observe groundwater sampling. PHS/EHD observed a number of practices that might <br /> affect the reliability of sample results. The following comments are offered to improve <br /> field techniques. <br /> PHS/EHD was informed by Sierra Environmental staff that, by policy, only two water <br /> quality parameter measurements are taken towards the end of the purging process. <br /> Temperature, pH, and conductivity parameters should be measured at regular intervals <br /> throughout the purging process. The LUFT manual states that purging of monitoring <br /> wells should continue, prior to sampling, until temperature, pH, and conductivity <br /> parameters have been stabilized. Water level measurements should be taken after <br /> purging is complete to verify that the well has adequately recharged. <br /> The decontamination procedures that PHS/EHD observed may not prevent cross <br /> contamination between wells. Decontamination methods should be designed to reduce <br /> the potential for cross contamination between wells. The field method practiced <br /> consisted of a wash by pumping five gallons of soapy solution through the pump between <br /> wells. The soapy solution was not replaced between wells, therefore the wells <br /> decontaminated last utilized the same solution throughout the entire well <br /> decontamination process. At a minimum, decontamination should include a wash and at <br /> least one rinse with clean solutions for each well. <br /> Although water samples were stored in an ice chest with blue ice, the blue ice had begun <br /> to melt. Rearrangement of the samples did provide a cold environment for sample <br /> preservation. Please be informed that thermometers should be provided for each ice <br /> chest to verify adequate sample preservation. <br /> A Division of San Joaquin Counry Health tare Semces �� <br />