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3-11 Forward Composting Facility SWT Engineering Report of Composting Site Information - August 2019January 2022 z:\projects\allied waste\forward\resource recovery facility\5 yr permit rvw 2019-2020\rcsi 2019\text\sec 3.doc feet. This information was factored into the North Fork realignment of the South Littlejohn’s Creek relocation design. The North Fork of South Littlejohn’s Creek was relocated to allow continued development of the Forward Landfill. The 7,600-foot reach of the creek relocation was designed to channel the 100-year flood-flow of 1,025 cubic feet/second (cfs) wit hin its banks with an additional one foot of freeboard. In the event that a 500 -year flood occurs (1,100 cfs, according to FEMA Flood Flows), the excess flow will spill over the northern bank and into the adjacent farm land, rather than affecting Forward Landfill. Based on the realignment of the North Fork of South Littlejohn’s Creek, the landfill property is not located within the predicted elevation of the 500 -year flood zone. Therefore, the existing realignment does not require an assessment for potential erosion or saturation of the landfill. The South Fork of South Littlejohn’s Creek runs south of and adjacent to the southern perimeter of the refuse footprint of the landfill. From the FIRM map (Map No. 06077C Panels 0635F and 0630F), the existing So uth Fork of South Littlejohn’s Creek is labeled as “Zone AO, (Depth 1)”, indicating depths of one foot, and Zone AE, indicating b ase flood elevations within the creek. These current flows are very slow and non -erosive and as a result, will not inundate or potentially erode the adjacent creek or inundate the landfill. The predicted elevations from the 500 -year flood event range fro m 40.5 feet on the southwest edge to 43 feet on the east edge of the landfill along Austin Road and this level is only one to t wo feet higher than the toe of existing landfill slopes. The existing South Fork of South Littlejohn’s Creek was designed to channel the 100 -year flood flow of 1,550 cfs within its banks and an additional one foot of freeboard. In the event that a 500 -year flood occurs (1,700 cfs, according to FEMA Flood Flows), the excess flow will spill over the southerly bank and into the adjacent area, rather than impact the Forward Landfill. The South Fork of South Littlejohn’s Creek alignment is also a very flat gr adient, 0.0006 feet per foot; therefore, erosion is not a significant concern. Evaporation. The estimated annual evaporation fo r the site is 78.43 inches based on Pan A evaporation data recorded between 1919 and 1968 at Oakdale Woodward Dam (Station No. BOO 630500, latitude 37°51'28", longitude 120°52'42", Elevation 215 above mean seal level [amsl]), located approximately 13 miles southeast of the site (California Department of Water Resources, 1979). A minimum mean monthly evaporation of 1.14 inches has been calculated for December and January, and a maximum mean monthly evaporation of 14.69 inches has been calculated for July. Wind. During summer periods, winds usually originate from the north end of the San Joaquin Valley and flow in a south-southeast erly direction through the valley and Tehachapi pass, and then into the neighboring Southeastern Desert Air Basin. During winte r months, winds occasionally originate from the south end of the valley and flow in a north -northwesterly direction. During winter months, the valley experiences light, variable winds, less than 10 miles per hour (mph). Low wind speeds, combined with low inversion layers in the winter, create a climate conducive to high concentrations of certain air pollutants. The California Air Resources Board (1984) analyzed wind data for the Stockton Airport weather station for the period from 1964 to 1980. The prevailing wind for the Stockton station blows from the west -northwest (45.3 percent of the time) and the north (15.9 percent of the time). Calm winds occur 6.9 percent of the time. A wind rose (Figure 9) developed from the Stockton WB Airport station data provides wind direction information.