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: �` .:, ---_ '•:` xxs'-'s' x r.;,f,'� - , :s¢s•` T-Ki k sial aF8 v 9% ,. "�"x.a.°•3 ?.r#c`"^ .,^'G�'_ .zx �k5Y"z-^ - r" s s^It','."`-r r .r k °`3�i yp r I' H0C ED t11lF. iA Mothodoln,gieu and Vinventlana GVNERAL PRACTICES WITHIN A MULTIPLE; AGE,yCY 111EHAUCIly U.S. Environme.nttil Protection Agency ntandnrda nerva cis the foundhtion for ell field sampling operations performed by our firm, The EPA SW 84G In the • primary publication frorr, which procedures are derived, though there are additional EPA aourcea Ruch as training films and verbal communications. Sampling reIntrd to underground storage tanks and tank rotated threats to groundwater are governed by the California Water Renourcen Control Dor-rd and their Regional Water Qunlity Control Boards. While rome aspecta of fialri and laboratory work may be delegated to the California Department of licaith Services, the CWRCII and the nine Rag'onal Water Quality Control Boards establish the general and specific critorla for sampling performed in connection with undesrground storage tanks. Thin Is done through the publication of guidance docunients, the Issuance of memornndn and verbal announcements. Other agencies, such as Air Pollution Control Districts, may require J additional samples, but these are usually it ndd t n Lo samples required by the RWQCEI. Local Implementing agency (LIA) Inspectors are frequently presont. during the thnk removal phase of a project and either direct or request that samples be taken according to RWQCB specifications. Additional samples may, and frequently are, taken at the request of the LiA inspector. ' Based on field conditions directly observable by the LIA Inspoctor, our field personnel may be asked to collect samples that err tailored to the Specific situation and which the Inspector judges will provide substantiai Information about the site. Quite often these directions or suirgestionn k coincide with the sampling areae established by the RWQCH as the proper collection pointer for samples which will be used as the primary Criterir for a Regulatory Agency Determination on whether additional exploration or remedlation will be required at a particular site. Similarly, there are Instances when the LLA Inspector's judgements do not coincide with hoard specifications. TwO common examples of this arc an follows: I. A local implementing agency inspector notes that Boil dug up from the correct RWQCB Interface sampling point is relatively clean, but observes that there Is quite obviously contaminated backfill underlying the center of the tank. The inspector direct* that the contaminated backfill should be taken sa€l-acs-as....to-provido inform tion abssut--tha — - "worst case" conditions within the tank pit. 2. The sell at the specified Interface sampling depth In found to be slightly contaminated, Fut much lass so than the sell only a few inches: above. Doting Sampling Mmort 8WS5-C-2 C31$VllD.4 1218 page 7