CORRESPONDENCE_1991-2001 - Laserfiche WebLink

Home Browse Search

j Ms. Wendy Arano Project No.: 791291 June 7, 2001 Page 4 of a release from the landfill in 1989. This was the first year that quarterly monitoring was initiated, thus meeting both basic criteria of the regulations. The purpose of the EMP is have a sufficient number of monitoring points to provide the data needed to evaluate changes in water quality due to the release from the landfill unit. The existing shallow monitoring wells at the CHSL have also functioned properly in accordance with the requirements of an EMP. The existing shallow wells along with the information gathered from LFG monitoring probes, LFG extraction wells, and exploratory borings were sufficient to define the nature and extent of the release. The purpose of the CAP is have a sufficient number of monitoring points to provide the data needed to evaluate the effectiveness of the corrective action program. With the completion of the corrective action measures at the landfill the existing shallow wells along with the LFG probes will be used to track the effectiveness of the final cover and the LFG extraction system to remediate the release. Since the extent of LFG release, which caused the shallow VOC groundwater contamination, is limited to the northeastern portion of the landfill no additional monitoring points are necessary to evaluate the corrective action measures. Listed below are reasons why the installation of new deeper groundwater monitoring wells are not necessary: • Although the shallow groundwater zone is not present in the southwestern portion of the landfill, the LFG probes in the southwestern portion of the landfill do not indicate the presence LFG. Apparently the mechanism for deep groundwater contamination in the southwestern portion of the landfill is limited. Therefore, the installation of a deep well in the southwestern portion of the landfill is not necessary. • Because the EMP has shown that the source of VOC release from the landfill is solely from LFG, the best assurance of the earliest possible detection of a release in the southwestern portion of the landfill is the continual monitoring of the vadose zone gases by the existing of LFG probes. Therefore, the installation of a deeper well in the southwestern portion of the landfill, or in any other portion of the landfill would not provide the best assurance of the earliest possible detection of a release as required by Title 27 Section 20415(b)(1)(B). \\SACRFPI\COMMON\sacDP\2001\PRJ\PJ7\791291.1 aa.doc (00006000)