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Response to Comments on Tentative WDRs -3- 16 March 2009 <br /> p Harney Lane Landfill <br /> San Joaquin County <br /> Several groundwater wells now are in place in the Transient Labor Housing facility, and <br /> May be at locations suitable for upgradient monitoring. However, as written, the . <br /> Findings and Provision require the installation of wells regardless of the suitability of <br /> existing wells. . . we suggest that the wording of those Findings and that Provision be <br /> revised to reflect the intent, requiring "monitoring of groundwater"rather than <br /> "installation of wells". <br /> b. Response -The findings and provision have been revised to allow utilization of <br /> an existing monitoring well in lieu of installation of a new well provided that it is <br /> suitable for background monitoring purposes. <br /> 4. Unsaturated Zone Monitoring (MRP Page 5) <br /> a. Excerpt From Comment <br /> A rotating schedule will be very difficult to follow . . we suggest that the MRP require <br /> sampling LFG from a single monitoring point on the LFG header that serves the portion, . <br /> of the landfill in question (Figure 1). . . The Tentative MRP identifies two triple-probe soil <br /> gas wells (GW-9 and-10) from which samples for VOC analyses would be taken. . . <br /> As with the rotating monitoring of LFG wells, this complexity provides many <br /> opportunities for failure. . . Instead, I propose that we select one probe from each well to <br /> monitor, and once selected, monitor that probe thereafter. . . We also discussed how <br /> ambient temperature is not relevant to our monitoring interests, and I suggested that <br /> this parameter be removed. <br /> b. Response — Section D.1 of the MRP (unsaturated zone monitoring points) will be <br /> revised as follows: . <br /> LFG monitoring shall, at a minimum,be conducted at the following locations: <br /> ................._._........ ............ <br /> I Landfillitorin Interval Location i Sample Ty a MonPo <br /> ..................._......................__....._...._..._. _...........---- ----- . _._.__._..__.... ..__.._..... <br /> � �. _._..._ Points <br /> -� <br /> 1 i Middle Perimeter Monitoringam— GW-9M, GW-10D <br /> 1 ! Deep In situ Extraction East header <br /> 2 c Deep In situ j Extraction East or west header <br /> The LFG monitoring points shall also include, for a given monitoring period, <br /> any perimeter gas well that exceeds 5 percent methane by volume during that <br /> period, as measured under the perimeter migration monitoring program <br /> required by the Local Enforcement Agency.. <br /> Temperature will also be deleted as a parameter from the monitoring schedule. <br /> 5. Site Address (Finding 1) <br /> a. Excerpt From Comment I suggest that the address of the site be included. . . <br /> b. Response - Existing description adequately identifies site location. No change <br /> warranted. <br />