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Additional soil and groundwater sampling was performed by Ramage using cone penetrometer <br /> testing (CPT). This data showed additional sand strata present at depths of about 60 feet and 105 <br /> feet below site grade. The deepest groundwater sample collected at 115 feet showed petroleum <br /> hydrocarbon and1,2-DCA contamination. <br /> The dissolved plume has been partially defined by the previous work. However, discussions <br /> between Ramage and PHS EHD indicated that additional work is needed off site and to the east. <br /> On the basis of these discussions and previous reports, three aquifer zones of interest for this <br /> additional delineation are to be monitored: strata to depths of about 50 feet (currently monitored <br /> by existing wells), strata at the 60-foot depth and strata ,at the 105-foot depth. PHS EHD <br /> suggested three monitoring 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 January 27, 2003. Those tasks are <br /> identified here as Task 1 through 4 based upon Wrights understanding of that letter dated January <br /> 27, 2003. This work plan is to complete Task 1 of the directive issued by PHS-EHD. Tasks 2, 3 <br /> and 4 are provided to show the relationship this study has to implement directives issued by PHS- <br /> EHD, <br /> Task 1 - Preparation of Work Plan for Ground Water Plume Definition <br /> Wright will review available site and regional data including well logs, site cross sections and site <br /> . maps. Wright will submit a work plan to PHS EHD to define the lateral and vertical extent of the <br /> groundwater contamination plume taking into consideration. the recommendations made by PHS <br />' EHD in their letter dated January 27, 2003. Concurrent to this task Wright will assist RP with <br /> request to SWRCB for additional fund commitment and any.pre-approvals that may be required. <br /> I Task 2 - Site visit,Data Review and Analysis,Conceptual Site Model <br /> Wright will review available site and regional data such as contaminant concentrations, well logs, <br />- site cross sections and site maps. Wright will research and compile additional data required for <br /> fate and mobility calculations. This includes soil/aquifer properties (permeability, porosity, <br /> dispersivity) and physical/chemical 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 volume and ground water extent affected; <br /> and, the mass of CDCs in soil, dissolved phase and non aqueous-phase liquids(NAPL) present. <br /> Task 3 - Screening Level Evaluation of Interim Remediation Measures <br /> We will perform screening level calculations to estimate transport of CDCs in ground water for <br /> potential IRMs 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. Calculation <br /> results will be compiled and presented in appropriate graphical or tabular format. Ground water <br /> extraction will be compared to the potential effectiveness:of two or three 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 IRM and need for testing <br /> will be evaluated. <br /> i <br /> Page 2 of 2 <br /> t <br /> 3 <br />