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JOHN LANE <br /> PAGE 2 <br /> cubic feet per minute. This flow rate, along with a vacuum of 30 inches of water applied at the well <br /> head, was recommended to effect the radius of influence specified in the corrective action plan. The <br /> flow rates being reported for the system at this site, if correct, are considerably below this design <br /> specification. In addition, the vacuum being applied at the well heads are also considerably lower than <br /> what was indicated for the design. <br /> Please explain the discrepancy between the original design parameters and the actual operating <br /> values of the vapor extraction system. Please include all calculations used to design the <br /> system, especially those calculations used to determine the flow restrictions through the <br /> elbows and tees and over the length of the pipes. Specifically, PHSIEHD is interested in the <br /> data used by Clearwater to determine the size and configuration of the piping and the size of <br /> the vacuum pump. <br /> The tables in Appendix C showing the values and the formula for calculating recovered hydrocarbons <br /> are difficult to interpret and follow. It is uncertain whether the flow rates used in the calculations are <br /> correct. In addition, although the actual values are small, the concentrations reported in the second <br /> table on the first page are all zero. Using these reported values, the result of the calculations would <br /> also be zero. Because time for review is limited, please submit to PHS/EHD complete <br /> calculations in a format that can be easily read and duplicated. <br /> PHSIEHD has reviewed the letter proposing to measure biogenic gasses at this site. As PHSIEHD has <br /> not yet had the opportunity to effectively review any representative data from the site, the <br /> implementation of this proposal would be premature at this time. In addition, this type of information is <br /> estimative and assumptive, and would unlikely be useful at this site, given the almost ideal conditions <br /> for soil vapor extraction. <br /> Please provide all the above noted submittals to PHSIEHD by June 30, 1995. If you have any <br /> questions or wish to discuss this letter in more detail, please contact Linda Turkatte, Senior REHS, at <br /> (209) 468-3441. <br /> Donna Heran, REHS, Director <br /> Environmental Health Division <br /> 4 A& ' VJV,_� 1% <br /> Linda Turkatte, Senior REHS Diane M. Hinson, REHS <br /> Site Mitigation Unit Supervisor <br /> c: CVRWQCB, Beth Thayer <br /> c: SWRCB Cleanup Fund, George Lockewood <br /> C.* Margaret Ekholm <br /> c: David Wood <br /> c: Neumiller and Beardslee, Brooke Birke <br /> C.' Clearwater Group, Juniper Neill <br />