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P4/23/2003 15:41 20983251 ! WRIGHT ENVIRONMEN PAGE 04 <br /> Additional soil and groundwater sampling was performed by Ramage using cone peg ctr;7meter <br /> testing(CPT). This data showed additional sand''suata present at depths of about 60 feet acid 105 <br /> feet below site grade- The deepest groundwater umple collected at 115 feet showed pet:-oleum <br /> hydrocarbon and 1,2-DCA contamination. <br /> The dissolved plume has been partially defined by the previous work. Hawev6r, disci msions <br /> between Ramage and PHS EHD indicated that additional work is needed off site and to tt a east. <br /> On the basis of these discussions and previous 'Keports, three aquifer zones of interest t ar this <br /> additional delineation are to be monitored.- stratito depths of about 50 fit (curreWy mordtored <br /> by existing wells), strata at the 60-foot depth 'and strata at the 105-foot depth. PRE', EHD <br /> suggested three monitorin wells to be installed to the 60-foot depth and one to the 105-115 foot <br /> depth!. <br /> PHS-EHD directed several additional tasks in the!letter dated 7anuary 27, 2003. Those tas are <br /> identified here as Task 1 through 4 based upon W ;; k <br /> rights understanding of that letter.dated January <br /> 27, 2003. This work plan is to complete Task X.of the directive issued by PHS OW. Tas is 2, 3 <br /> and 4 are provided to show the relationship this study has to Oplement directives issued b3: PHS- <br /> Task X -1Pireparation of Work Pfau for Ground Water Plume Defiinition <br /> Wright will review available site and regional data including well logs, Site cress sections a:ad site <br /> reaps. Wrilgbt will submit a work plan to PHS EIUD to define the lateral and vertical extent!ofthe <br /> groundwater contamination plume taking into consideration the recommendations made by PHS <br /> EHD in their letter dated January 27, 2043. Co6urrent to this task Wright will assist R13 with <br /> request to SWRCB for additional fund commitmeiit and any pre-approvals that maybe required. <br /> Task 2- Site visit,Data Review and Analysis,Conceptual Site Model <br /> Wright will review available site and regional clan such as count concentrations, we.l logs, <br /> site cross sections and site snaps. Wright will research and cvrnpile additional data req*"Od for <br /> fate and mobility calculations. This includes 1,soil/aquiEfer properties (permeability, perosity, <br /> dispersivity) and physical/chernical properties (Henry's constant, solubility, sorption coefficient, <br /> vapor pressure)of the Chemicals of Concern(CDCs)- Wright will identify data gaps if any. From <br /> available data we will estimate, the contaminated soil volumeand ground water extent of xted; <br /> and,the masa of CDCs in soil, dissolved phase acid noir aqueous-phase liquids(NA]PL)presemt. <br /> Task 3-Screwing Level Evaluation of Interim Remediation Measures <br /> We will perform screening level calculations to e6rnste transport of COCl in ground water for <br /> potential 1RMs such as ground water extraction. These calculations will be performed using <br /> available site data and literature estimates of soil'properties where data, are lacking- Cala dation <br /> results will be compiled and presented in appropriate graphical or tabular fomut. Groundwater <br /> extraction will be compared to the potential Activeness of two or tb ree alternative measures <br /> such as ozone injection or application of oxygen releasing compounds and enhanced � <br /> biodegradation. The appropriateness of ground water extraction as an JRM and need for °:esdng ' <br /> will be evaluated. i <br /> Pag a 2 of 2 <br />