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11 <br />LCRS Design - Area 28 <br />Foothill Sanitary Landfill <br />TABLE 1- MONTHLY PRECIPITATION DATA <br />YEAR <br />JAN <br />FEB <br />MAR <br />APR <br />MAY <br />JUN <br />JUL <br />AUG <br />SEP <br />OCT <br />NOV <br />DEC <br />TOTAL <br />2001 <br />3.33 <br />2.64 <br />1.94 <br />1.99 <br />0 <br />0.08 <br />-----1 <br />0 <br />0.24 <br />0.44 <br />2.91 <br />6.60 <br />20.17 <br />2002 <br />1.62 <br />0.86 <br />2.92 <br />0.10 <br />-----1 <br />0 <br />0 <br />0 <br />0 <br />0 <br />2.58 <br />7.52 <br />15.60 <br />2003 <br />0.32 <br />1.26 <br />2.78 <br />5.73 <br />0.39 <br />0 <br />0 <br />0.3 <br />0 <br />0 <br />2.23 <br />4.77 <br />17.78 <br />2004 <br />3.20 <br />4.47 <br />0.44 <br />0.53 <br />0.23 <br />0 1 <br />0 <br />0 <br />2.69 <br />3.74 <br />18.53 <br />Average' <br />4.44 <br />3.73 <br />2.24 <br />1.53 <br />0.84 <br />0.09 <br />0.00 <br />0.051&M <br />2.30 <br />3.91 <br />20.14 <br />1 Too many missing days in monthly record and wasn't included in calculation of monthly average <br />2 Average monthly values entered into HELP model for generation of synthetic precipitation data <br />In addition to precipitation, temperature, and solar radiation, input pertinent to <br />evapotranspiration calculations within the HELP model include the evaporative zone depth, <br />maximum leaf area index, growing season start and end dates, average annual wind speed, and <br />the average relative humidity for each quarter in the year. HELP model defaults for Sacramento, <br />California were used along with information used in the previous HELP analysis completed by <br />Geosyntec (2014). <br />4.5 Material Properties <br />Summaries of the soil and material properties for the simulated profiles are shown in <br />Attachment 1 of this report. The HELP model default values were used for characterizing the <br />refuse, GDN, and geosynthetic layer. Soil properties were based on Geosyntec (2014) inputs for <br />Area 2A, which incorporated CCW test results from Module 1 construction. <br />Initial moisture contents were not specified, and therefore, defaulted to the steady state <br />moisture conditions established by the model, which are at or near field capacity. The <br />placement quality for the primary HDPE geomembrane was assumed to be "good" with 1 <br />installation defects and 1 pinhole per acre. GDN floor drainage has a maximum distance of <br />about 84 feet (100 feet was conservatively entered into HELP model) from any given ridge crest <br />to a LCRS drain pipe (see Figure A) at a minimum slope of 2 percent. The side slope GDN has a <br />maximum drainage distance if roughly 96 feet (100 feet was conservatively entered into HELP <br />model) at a minimum slope of 3:1(H:V). <br />Waste was modeled at a thickness of 15 feet, 145 feet, and 300 feet for the base LCRS. The side <br />slope LCRS was modeled with an average thickness of 7.5 feet corresponding to a critical waste <br />fill scenario of 15 feet. The final cover configuration used for the 145- and 300 -foot filling <br />scenarios was considered to be a 3 -foot -thick soil layer with no geomembrane (i.e. water <br />balance cover) with a fair stand of grass present. <br />4.6 Results <br />Water balance predictions for Area 2B are shown in Table 2 below, and HELP model output files <br />are included in Attachment 1. <br />Project No. AU17.1254 I LCRS Design 6 <br />May 2018 <br />