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F <br />I <br />J <br />P R O C E D U R E S <br />Methodologies and Conventions <br />GENERAL PRACTICES WITHIN A MULTIPLE AGENCY HIERARCHY <br />U.S. Environmental Protection Agency standards serve as the foundation for <br />all field sampling operations performed by our firm. The EPA SW 846 is the <br />primary publication from which procedures are derived, though there are <br />additional EPA sources such as training films and verbal communications. <br />Sampling related to underground storage tanks and tank related threats to <br />groundwater are governed by the California Water Resources Control Board and <br />its Regional Water Quality Control Boards. While some aspects of field <br />and laboratory work may be delegated to the California Department of Health <br />Services, the CWRCB and the nine Regional Water Quality Control Boards <br />establish the general and specific criteria for sampling performed in <br />connection with underground storage tanks. This is done through the <br />publication of guidance documents, the issuance of memoranda, and verbal <br />announcements. <br />Other agencies, such as Air Pollution Control Districts, may require <br />additional samples, but these are usually in addition to samples required by <br />the RWQCB. Local implementing agency (LIA) inspectors are frequently present <br />during the tank removal phase of a project and either direct or request that <br />samples be taken according to RWQCB specifications. Additional samples may, <br />and frequently are, taken at the request of the LIA inspector. <br />cased on field conditions directly observable by the LIA inspector, our field <br />personnel may be asked to collect samples that are tailored to the specific <br />situation and which the inspector judges will provide substantial information <br />about the site. Quite often these directions or suggestions coincide with <br />the sampling areas established by the RWQCB as the proper collection points <br />for samples which will be used as the Primary Criteria for a Regulatory <br />Agency Determination on whether additional exploration or remediation will be <br />required at a particular site. Similarly, there are instances when the LIA <br />inspector's judgements do not coincide with Board specifications. <br />Two common examples of this are as follows: <br />L 1. A local implementing agency inspector notes that soil dug up from the <br />correct RWQCB interface sampling point is relatively clean, but observes that <br />there is quite obviously contaminated backfill underlying the center of the <br />F tank. The inspector directs that the contaminated backfill should be taken <br />instead of the clean interface soil so as to provide information about the <br />"worst case" conditions within the tank pit. <br />2. The soil at the specified interface sampling depth is found to be slightly <br />contaminated, but much less so than the soil only a few inches above. Noting <br />the relatively dense soil, the local implementing agency inspector decides <br />not to have the interface soil sampled and has the backhoe dig deeper to see <br />Sampling Report 88280-M-1 CHEVRON 4054 page 8 <br />