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4) The report does not include sufficient data to evaluate the slug tests. Copies of the chart records, information on the type of transducer used, assumptions used in calculations, etc. should be submitted for this report and included in subsequent reports. DHS agrees with Radian that the slug tests results are somewhat suspect due to the factors discussed in sections 3 .4 and 4. 3 . Additionally, slug tests usually are accurate only within two orders of magnitude and, because of the spatial limitations inherent in the test, slug test results should not be extrapolated to characterize large untested portions of an aquifer. SOW for Next Phase 1) This scope of work continues the methodology of using soil vapor surveys as an initial screening tool for contamination. DHS considers this to be on the borderline of proven technology and therefore requires substantial documentation and verification of results by soil and groundwater testing. Additional required documentation is specified in attached Attachment II. The proposed methodology has one major failing in that it essentially chases the plume of contamination rather than monitors the leading edge and points beyond. With the results of a pump test(s) , piezometer data, and the sampling data Radian should be able to predict the approximate spatial and temporal aspects of plumes and place monitor wells in advance of and along the leading edge of these plumes. DHS recommends that flexibility in the SOW be provided to allow for this type of approach. Early placement of monitor wells in advance of the plume will also expedite selection and design of remedial actions and later evaluation of remedial actions. 2) Section 3 .9 . 1 (last sentence) : Monitoring of the deepest contaminated zones and initial monitoring of the underlying zone is required. The latter monitoring can be discontinued after samples confirm the lack of contamination at this depth. The potential for downward migration of contaminants at this site emphasizes the need for monitoring of the deeper zones. 3) Section 4 . 3 . 2 : Thin walled samplers should be given preference. 4) Section 4 . 3 . 4 : Grain size analysis must be done where the screen will be located to properly design the sand pack. 5) Section 4. 4 . 4 : DHS recommends a sand pack envelope between three and five inches. Jay IAXcas- Associate Engineering Geologist a� fig