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Mr. Marshall Cloud • - 2 - 25 February 2008' <br /> Defense Logistics Agency <br /> DECISION LOGIC COMMENTS <br /> The Draft Report presents a revised Decision Logic for monitoring well sampling at the Site, <br /> three key components of which are the well type, the sampling frequency for each type, and <br /> an introduced variable titled preferred well. <br /> Well Type. The well type is defined by the position of the well in relation to the plumes of <br /> contaminants of concern. The annual groundwater monitoring for 2004 through 2007 utilized <br /> a Decision Logic with the following well types: New Well, Guard Well, Judgment-Based Well, <br /> Source Well, and Up- or Cross-Gradient Well. For groundwater monitoring in 2008, DESJC <br /> proposes a new Decision Logic utilizing the following well types: New Well, Guard Well, Plume <br /> Core Well, Plume Stability Well, and Up-Gradient Background Well. The following tables <br /> summarize both Decision Logic schemes. <br /> 2004 through 2007 Groundwater Monitoring: <br /> Well Type Sampling Frequency Description of Well Type <br /> New Q' Less than 4 samples analyzed by laboratory <br /> Guard Q Clean, D-GS of Source and U-G' of receptor <br /> Judgment-Based SA' or A' CDCs significantly above baseline? Yes-SA; No-A. <br /> Near Source SA, A, or BA" Within Plume near Source <br /> Up-/Cross-Gradient SA, A, BA, or None U-G or C-G' to plume <br /> Proposed 2008 Groundwater Monitoring: <br /> Well Type Sampling Frequency Description of Well Type <br /> New Q Less than 4 samples analyzed by laboratory <br /> Guard SA or None D-G of Source and U-G of receptor <br /> Plume Core A or None Within Plume and at or near Source <br /> Plume Stability SA or None Within Plume, and C-G or D-G of Source <br /> Background BA or None U-G of Source <br /> Notes: 1. Q = Quarterly <br /> 2. S-A=Semi-annual <br /> 3. A=Annual <br /> 4. B-A= Bi-annual <br /> 5. D-G = Down-gradient <br /> 6. U-G = Up-gradient <br /> 7. C-G =Cross-gradient <br /> Regional Water Board staff has no objections to the proposed well types for the 2008 <br /> Groundwater Monitoring Decision Logic. However, before we can comment on the proposed <br /> sampling frequencies, DESJC must present their rational for the changes. <br /> Sampling Frequency. The tables above show that DESJC is proposing significant reductions <br /> in the frequencies that various well types would be sampled. For example, Guard Wells are <br /> currently sampled quarterly, but would be sampled semi-annually or not at all under the <br /> proposed sampling frequency. However, the Draft Report does not justify reducing the <br />