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immaturity of the plant community and the dry conditions typical during the first year of monitoring,the development of vegetation is somewhat stunted and it is unlikely that the optimal (48-inch)rooting depth has yet been achieved. As a result,the ultimate performance of the alternative cover has not yet been realized. Appendix B includes recent pictures of the vegetation that has developed at each of the monitoring locations. 5.0 DEMONSTRATION PROJECT CLIMATIC CONDITIONS The following sections summarize the climatic conditions as recorded over the last year of monitoring at the weather station located at the Met monitoring station(Figure 1). Climatic conditions at the Forward Sanitary Landfill Stage 1A final cover area are considered to be semi- arid. The climate is characterized by wet winters and humid temperate summers. 5.1 RAINFALL,EVAPORATION,AND SOLAR RADIATION Historical average precipitation for the area for the years 1988-2006 averages 13.22 inches per year, as recorded at the Manteca California Irrigation Management Information System (CIMIS) Station(less than 4 miles away). Historical potential evapotranspiration recorded at the same station averages about 51.03 inches. During the first year of monitoring,total rainfall at the site was approximately 6.14 inches (Figure 5) and potential evapotranspiration measured at the Manteca Station totaled 54.97. The mean daily solar radiation at the site averages about 5015.2 Watts/m2 (431.5 Langleys) during the monitored period with the historical daily solar radiation averaging 415.2 Langleys over the 1988-2006 monitoring years. 5.2 RELATIVE HUMIDITY AND BAROMETRIC PRESSURE Figure 6 illustrates the pattern of relative humidity observed at the Forward Sanitary Landfill Stage 1 A final cover area over the monitoring period. As shown therein, relative humidity was generally higher from late fall through winter(December—March). During the first year of monitoring, the average relative humidity at the FSL was about 61.6%. It is noted that this observed value is slightly lower than the historical average relative humidity of 69.1%that was measured the Manteca CIMIS station between 1988 and 2006. Barometric pressure data was recorded at the 10 Street Station in Modesto, California, the nearest barometric station to the site. As shown on Figure and remains fairly steady during the warmer months (late April through September) and increases dramatically during the fall and winter months with significant drops in pressure (greater than 20 millibars)observed during this period. 4 Geologic Associates