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1 KLE/NFELOER <br /> "fight People.Right 5olutians. <br /> • Layer 2 (barrier layer), 12 inches thick, clay (HELP soil texture #16, <br /> hydraulic conductivity adjusted to 1x10-6 cm/sec) <br /> • Layer 3 (foundation layer), 24 inches thick, sandy silt (HELP soil texture #7) <br /> The modeled results showed 944.84 cu ft seepage. Results of the HELP modeling g are <br /> summarized in Table 1. The HELP modeling printout can be found in Appendix B. <br /> Chart 1 shows the rainfall vs. seepage volume with actual and modeled data. <br /> Performance of the ET Test Pad (using seepage out of the bottom of the cap) was <br /> compared directly to the modeled performance of the Title 27 Prescriptive Cap. <br /> 2.5 Soil Moisture Monitoring <br /> Soil moisture sensors were installed with the ET cover at the request of RWQCB staff; <br /> however, soil moisture is not a criterion for ET cover evaluation. This data presents <br /> monitoring data collected since fall 2006. <br /> 2.6 Historical Discussion <br /> The Test Pad was fitted with soil moisture sensors set at depths of 1, 2 and 3-feet below <br /> the ground surface. Soil moistures in 2006/2007 were low, a reflection of the recently <br /> constructed ET Final Cover. The variability in the shallowest probe was greatest, as it <br /> was influenced most heavily by the cycles of wetting and drying caused by alternating <br /> periods of precipitation and sun. The response of the shallow probe to rainfall (1.6- <br /> inches in December) showed an increase in soil moisture. <br /> Precipitation events in the 2007/2008 water year elicited a corresponding change in <br /> moisture content at all three depths. February, April, October, and December were <br /> heavy rainfall months (greater than 0.75-inches in the month) for the year. Nearly 3- <br /> inches of rain in February caused a rise in moisture content at all three depths, with the <br /> largest increase at the 1-foot level and the smallest at the 3-foot level. Rainfall in April <br /> (1.2-inches) caused a smaller increase at the 2-foot and 3-foot levels. A period of <br /> drying occurred during the summer with the moisture content of the 1-foot level and <br /> dropped below that of the 2- and 3-foot depths. <br /> 47717.111ST01 OR310 Page 5 of 8 August 31, 2010 <br /> Copyright 2009 Kleinfelder <br />