ARCHIVED REPORTS_2010_2 - Laserfiche WebLink

Home Browse Search

THOMAS R. FLINN P.O.BOX 1810-1810 E.HAZELTON AVENUE STOCKTON,CALIFORNIA 95201 DIRECTOR (209)468-3000 FAX(209)468-2999 WWW.sjgov.org/pubworks THOMAS M.GAU CHIEF DEPUTY DIRECTOR MICHAEL SELLING Worldmg for YOU \ !q DEPUTY DIRECTOR J � Li STEVEN WINKLER DEPUTY DIRECTOR ROGER JANES N V 1 i iU BUSINESS ADMINISTRATOR E N - FNT H September 1, 2010 EALTH Mr. Todd Del Frate PER IVI IT/SERVIC ES California Regional Water Quality Control Board 11020 Sun Center Drive, #200 Rancho Cordova, California 95670-6114 SUBJECT: EVAPOTRANSPIRATION CLOSURE COVER REPORT 2009/10 WATER YEAR, FOOTHILL SANITARY LANDFILL Dear Mr. Del Frate: Please find enclosed, the report from Kleinfelder Inc. (dated August 31, 2010) presenting the results of the Evapotranspiration (ET) test pad monitoring at the Foothill Sanitary Landfill. We are most pleased to report that the measured seepage through the ET cap was approximately one-half of the seepage rate calculated with the HELP model for the Title 27 prescriptive cover (Table 1 and Chart 1). As we agreed, the criterion for acceptance of the ET cover as closure is that the measured seepage rate of the ET test pad should be no more than the calculated seepage rate of the Title 27 prescriptive cover. Based on this criterion, it appears that the ET cap has performed above that requirement for this year. We will continue to monitor the ET test pad, and are cautiously optimistic that next year's data will be similarly positive. As discussed in our semi-annual groundwater report, the surface was grazed in May and early June. The objective of this gazing was to reduce annual grasses (some of which had immature seed at that time) to the benefit of perennial grasses. The ET area was mowed since, which reduced the shade provided by dead stalks to active perennial grasses. Perennial grasses, such as purple needle grass, are preferred for the ET cover because these grasses send roots deep into the soil, removing moisture by evapotranspiration. Some perennial species, such as purple needle grass, are active throughout the hot summer and fall months, bringing moisture to the surface foliage for evaporation.