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Surface Water Surface water samples were last retrieved on March 4, 2009. All concentrations of monitoring and field parameters were below established concentration limits where the limits could be determined. HISTORICAL TIME SERIES PLOTS AND STIFF DIAGRAMS Constituents not detected are plotted at a value of half their respective detection limits in the Historical Time Series Plots(Appendix F). Outliers were included in the plots as directed by RWQCB staff. Stiff diagrams are submitted annually with the second semester and annual report. The stiff diagrams submitted for the first and second semesters indicate a calcium-bicarbonate water type since these ions have the highest concentrations in the six wells (Appendix F). The water type is similar in all wells as indicated by similarity in concentrations of the various constituents and the similarity in diagram shapes. This similarity indicates that the groundwater is not impacted as it moves under the landfill. The shapes of the diagrams between the first and second semesters are also very similar indicating that the general groundwater quality has not changed throughout the year, which is also an indication of no impact from the landfill. PROGRESS OF EVAPOTRANSPIRATION COVER VEGETATION The purpose of the evapotranspiration cover is to capture rain water during the wet months, AML 1p allowing the vegetation growing on that cover to remove the water from the soil during the dry months. For all practical purposes, the evapotranspirative(ET) cover was established in December 2008 when soil in areas without sufficient growth were amended, fertilized and reseeded. Growth in the spring of 2009 was successful. Weeds were pulled in early May 2009 to reduce intrusion of wind- blown seeds into the preferred species. In June 2009, growth was between three and four feet high. Early rains of November 2009 allowed the germination of annual seeds and revitalizing perennial grass roots. A key component of this method is the root structure established. Perennial plants, such as purple needle grass and California Brome grow deep roots that can gather moisture from deep within the closure soil layer. In contrast, annual species, such as rye grass, produce shallow roots. The survival"strategy"of annual grasses is to produce a significant quantity of seed in the spring before dying. This seed then germinates in the rains of the following winter. For the purposes of maximizing evapotranspiration, deep-rooted perennial species are much preferred over shallow-rooted annual species. The County is contemplating allowing grazing by sheep during the spring of 2010,timed to reduce the annual grass stalk and seed crop, thereby enhancing the proliferation of perennial species. Foothill Sanitary Landfill 15 Department of Public Works/Solid Waste 2"d Semester and Annual 2009 Groundwater Monitoring County of San Joaquin—January 31,2010