Laserfiche WebLink
Mr. James L. Barton <br /> August 31, 2009 <br /> Page 3 <br /> concentrations for the respective monitoring wells (i.e. TPHg concentrations in MW-2 pre-startup <br /> were 15,000µg/L,therefore significant rebound would be concentrations greater than 1,500 µg/L. <br /> See the table below with the rebound criteria for each well). Dissolved concentrations of both <br /> TPHg and benzene will be evaluated for rebound against these criteria. <br /> April 2008 Groundwater "Significant" Rebound <br /> Well ID Concentrations L Concentration Criteria L <br /> E7,300 <br /> PH Benzene TPHgBenzene <br /> MW-25,000 350 1,500 35 <br /> MW-32,000 4,500 3,200 450 <br /> MW-8D 1,800 730 180 <br /> MW-11 ,200 1,300 520 130 <br /> • If concentration rebound exceeds the 10%criterion,the AS/SVE system will be re-started within <br /> 30 days of rebound sampling. <br /> • The system will continue to operate for 6 weeks, followed by another 6-week shutdown and <br /> sampling of the wells. The controlled pulsing (alternating schedule of 6 weeks of continuous <br /> operation and 6 weeks of shutdown) will allow AECOM the opportunity to evaluate if active <br /> remediation is still warranted at the Site. <br /> Schedule <br /> AECOM requests that the CVWB review the proposed rebound testing plan and provide a response by <br /> September 15,2009 so that testing can be implemented during the Fourth Quarter of 2009. <br /> Remarks/Signatures <br /> The interpretations in this request represent AECOM's professional opinions and are based, in part, on <br /> information supplied by the client pertaining to monitoring and remedial activities that occurred prior to <br /> AECOM's involvement with the Site, which began in 2003. These opinions are based on currently <br /> available information and are arrived at in accordance with currently accepted hydrogeologic and <br /> engineering practices at this time and location. Other than this, no warranty is implied or intended. <br /> If you have any questions regarding this project_Dleaae contact Jennifer Johnston at (916) 362-7100. <br /> Sincerely, Q INN,,-Uy <br /> AECOM Environments art yf <br /> nnifer P. .#C72990 �I I�d01 O Mark <br /> Senior Project Manager CIV[L �`p Senior Pproject Manager <br /> �f CAUF <br /> cc: Ms. Stephanie McKenna, Chevron Environmental Management Company <br /> Mr. Mike Infurna, San Joaquin County, Environmental Health Division <br /> Mr. Jay Allen, Stone Brothers Management Company <br /> Ms. Nicole Gleason; Downey Brand <br /> AECOM Environment AECOM <br />