Laserfiche WebLink
Page 1 of.2 <br /> Vicki McCartney [EH] <br /> From: David R. Daniels[david.daniels@cardno.com] <br /> Seat: Tuesday, January 31, 2012 8:16 AM <br /> To: Vicki McCartney [EH] <br /> Subject: RE: Former Mobil Service Station located at 25355 North Highway 99, Acampo, CA <br /> Attachments: 1,2 DCA Regressions.pdf <br /> Vicki, <br /> The 1,2 DCA trend evaluation for 25355 North Highway 99 in Acampo is provided below and in the <br /> attached graphs. Please contact me with any comments or questions. <br /> ESTIMATE OF TIME REQUIRED TO MEET WATER QUALITY NUMERICAL LIMITS <br /> Cardno ERI compared the dissolved-phase concentrations at the.site with Water Quality Numerical Limits <br /> (WQNLs) established by the California Regional Water Quality Control Board, Central Valley Region (CRWQCB- <br /> CVR 2004). <br /> Wells in which 1,2 DCA concentrations exceed WQNLs were graphed versus time and a first-order exponential <br /> decay trendline was added to show when WQNLs will be achieved. <br /> f Well MW1 <br /> 1,2 DCA concentration in well MW1 increased by approximately one order of magnitude during 2004 and have <br /> since declined. Cardno ERI prepared a regression based on the analytical'data following the 2004 increase. <br /> Based on the regression, the 1,2 DCA WQNL will be achieved in well MW1 in approximately 2021. - <br /> Well MW3 <br /> 1,2 DCA concentration in well MW3 increased do-a maximum concentration of 350 pg/L in December 2004 and <br /> have since declined. Cardno ERI prepared a regression based on the analytical data foltowin.g.the December. <br />` 2004 sampling event. Based on the regression, the 1,2 DCA WQNL will be achieved in well MW3 in <br /> approximately 2028. _.. <br /> I <br /> Well MW4 <br /> Well MW4 was first sampled in June of 2005 and does not show the increase observed in wells MW1 and MW3 <br /> during 2004. Cardno ERI prepared a regression based on the all of.the analytical data collected from well MW4. <br /> Based on the regression, the 1,2 DCA WQNL will be achieved in well MW4 in approximately 2014. <br /> Remaining Wells <br /> I <br /> l <br /> 11)1/2012 <br />