SITE INFORMATION AND CORRESPONDENCE

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n F. Define Plume Define the extent of contamination and for the number, location, and depth of Provide fationale or • For vertical definition, obtain non-detect samples 5 and 15 feet below known or suspected contamination: • For horizontal definition, borings should "step out', into clean soil/water and encircle the contamination. G. Groundwater If groundwater has been, or is Potentially impacted contamination within 25 feet of the historically highoil groundwater level) , wells must be installed. A down- gradient water sample must then be obtained. Well construction must comply with "Monitori Construction", Appendix C Page 32 . ng Well H. Sampling • Provide a sampling plan which includes the locations and number of samp es to be taken. - Samples must be taken at a minimum of five-foot vertical intery is or at vertical changes in soil lithology, or at areas of obvious contamination. An OVA may only be used to indicate the. presence Of contaminatioll. Samples must be analyzed in the laboratory to determine a level of contami- nation or to con irm the absence (ND) of contamination. - Discrete samples are £ u preferred. Composited samples (UP to four per boring) may be acceptable to confirm an absence of contamination if sufficient site assessment has been completed and approval h given by the P Proas been ject Engineer. samples containing a detectable level of contamination must xa be analyzed disc etly. • Describe sampling and handling protocol, (see `Y "Sampling Procedures", Appendix B, g procedures used to page 30) . Identify prevent cross Contamination. - Z. Lab Analysis d All laboratory analysis Must be Proposed according to "Laboratory Requirements .` Page 21. •F M1