Laserfiche WebLink
Pq�IN. <br />THOMAS R. FLINN <br />DIRECTOR <br />THOMAS M. GAU <br />CHIEF DEPUTY DIRECTOR <br />MICHAEL SELLING <br />DEPUTY DIRECTOR <br />STEVEN WINKLER <br />DEPUTY DIRECTOR <br />ROGER JANES <br />BUSINESS ADMINISTRATOR <br />Mr. Todd Del Frate <br />October 22, 2009 <br />California Regional Water Quality Control Board <br />Central Valley Region <br />11020 Sun Center Drive, #200 <br />Rancho Cordova, California 95670-6114 <br />P. O. BOX 1810 -1810 E. HAZELTON AVENUE <br />STOCKTON, CALIFORNIA 95201 <br />(209) 468-3000 FAX (209) 468-2999 <br />www.sjgov.org/pubworks <br />c�`'� J';D <br />ENVIRONMENT <br />�;�� T� � <br />�E M'' ��j <br />SUBJECT: RESOLUTION OF INVESTIGATION, MODULE 1 SECONDARY SUMP <br />FOOTHILL SANITARY LANDFILL <br />Dear Mr. Del Frate: I <br />'fi <br />This letter summarizes the results of our investigations to determine the disposition of the <br />landfill gas (LFG) condensate at the secondary sump of Module 1 at the Foothill Sanitary <br />Landfill. <br />Our investigations on October 8, 2009, showed that a seam had not ruptured, as was <br />originally supposed. Instead, we found that the primary and secondary liners were not <br />welded along the upper edge in the anchor trench (Figure 1 and Photo 1). <br />Without such a weld, condensate could move easily between the two liners, to be <br />dispersed along the anchor trench. Apparently, the flow of condensate was sufficiently <br />low and the anchor trench sufficiently long that the surface soil along the trench was not <br />visibly moistened. Although soil in the anchor trench was moist during our investigation, <br />but it was free of odors associated with LFG condensate, indicating that the volatile <br />components had evaporated. Distribution of the condensate along the trench, combined <br />with the distance from the anchor trench to groundwater (approximately 200 feet), has <br />apparently prevented groundwater contamination. <br />As part of our earlier investigations, a portion of the geocomposite drain layer over the <br />sump area was peeled back to expose the liner beneath. This geocomposite was <br />replaced to its original position, and a second layer of geocomposite was placed over the <br />first in this area (Photo 2). The operations layer was placed over that geocomposite <br />layer, thereby restoring the original condition (Photos 3 and 4). <br />We will continue to pump LFG condensate from the secondary sump as it slowly drains <br />from between the two liners, monitoring the amount removed. <br />