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� c. ��'�. � .-:.�_ '�3.��"�a��^� � � � ta {;.. c � s#'' � `3n�'i #'e3rq+r•. �_4'°er'.a�.n `sT'�s'3- _�, ,. --,� �e-nu .�y. eu ' � � <br /> 4 <br /> 1` <br /> P n 0 C r D U H R S <br /> Mnthoclo;o$les land Convention+c <br /> GRN£RAL PRACTICES WIT111N A MIII.TIPL►. AGENCY FiuEIZARCIfy <br /> U.S. Environmental Protection Agency standards serve ns the faundat,cn for <br /> all field sampling operations performrd by our firm. The EPA SW 848 is the <br /> primary publication from which procedures are der;vad. though there are <br /> additional EPA sources ouch us trairsing films and verbal communications. <br /> Sr,mpling related to underground atora,fe tanks and tan#; related threats to <br /> troundwater are governed by the Cal-fornia Water PaBources Control Board and <br /> their Re ,lona) Water Quality Control Board4, While some aspacta of field <br /> and laboratory work may be delegated tO the California Department ofHealth <br /> Services, the CWRCB and the nir_n Rog°oral Water Quality Control Boards <br /> E establish the general and specific criteria for sampling performed its <br /> connection with underground storage tanka. This is done through the <br /> publication of guidance documents, the issuance of memoranda and verbal <br /> announcements. <br /> ]then agencies, such as Air Pollution Control Districts, may require <br /> additional anmplvs, but these are usually L add tion tg namplos required by <br /> the RWQCB. Local Implementir.g agency VIA) inspectors are frequently present <br /> during tho tank removal phase of a project and either direct or request that <br /> samples be taken according to RW.JCO apscificstions. Additional samples may, <br /> and frequently are, taken at the request of the LIA inspector. <br /> 13eabd on field conditions <br /> directly observable by the LIA inspector, our <br /> g field personnel may be asked to collect Lamples that are tailored to the <br /> specific situation and which the inspector judges will provide altbstantial <br /> information about the site. Quite often these directions or suggestions <br /> coincide with the sampling areas cstabliahed by the RWQCB an the proper <br /> 3 collection points for samples which will be used as the Primary Criteria for <br /> a Regulatory Agency Determination on whether additional exploration or <br /> remediation will be required at n particular site. Similarly, there are <br /> instances when the LIA inspector's judgements do not coincide with Board <br /> specifications. <br /> Two common examples o: this are as follows: <br /> 1. A local implementing agency inspector notes that soil du u <br /> correct RWQCB interface sampling g , from the <br /> Y. <br /> there is quite obviously contaminatednbackl Ilaunderlyingnthe certarrof the <br /> ves at <br /> 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" rendiLions-withtn-the-tank-pit.-- - --- - - - - -- <br /> - -- 2. The soil at the specified interface snmpling depth is fount( to be slightly <br /> contaminated, but much less so than the soil only a few inches above. Noting <br /> Sampling Report 88055-C-2 CHEVRON 1818 page 7 <br />