ARCHIVED REPORTS_[REV] MAY & JULY 2014 RCSI

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2-9 2.1.4 Grading and Drainage Plan PFO~lide a schefR8tic dlawing 0'£ the grading plan for the site. Indicate how this design will prevent pondingand control rfdOOff. The grading and drainage plan (Figure 6+6) shows the proposed grading of the RRF/Compost Facility. The grading plan is the same for all of the potential composting options. A one percent minimum grade is provided at all points in the Compostffig Facility site. The composting windrows are arranged normal to the site slope to allow free drainage and minimize .Q..OL ponding. The composting pad will be constructed of compacted native soils. These soils are silt and clay and when compacted will provide a composting pad of relatively low-permeability soils . During periods of wet weather, the Compost Facility may suspend composting operations to prevent damage to the composting pad. Alternatively, economics may allow construction of a gravel surfaced or asphalt paved composting pad to allow continuous operations. During periods of extreme wet weather, the Compost Facility may choose to not accept wastes. The site is sloped to drain surface water to perimeter ditches designed to convey storm water from a 25-year, 10-minute duration storm event (0.25 inches, 1.5 inches per hour) assuming all the water that falls on the Compostffig Facility site runs off. The ditches will carry the water to a retent ion pond sedimentation (retention ) basin designed to hold the net average annual rainfall during months where rainfall exceeds evaporation (5.67 inches) assuming all the water that falls on the site composting runs off. This exceeds the 25-year, 24-hour rainfall event (2.28 inches). The location of the retention pond sedimentation basin is shown on Figure 2.e . All surface water runoff from the Compost Facility will be collected and stored in the sedimentation (retention ) basin and evaporated. If necessary, pond. Cc ollected runoff tfla.t has not contacted any waste, or has oontacted 'Naste but meets the '",ater quality criteria fo r storm water dischargesthat meets water quality criteria for stormwater discharge may be discharged to the South Fork or is either discharged to the South Forl~, used to add water to the initial compost mixture to provide the desired initial moisture content, or evaporated. If necessary. Al+-collected runoff which does not meet the water quality criteria for stormwater discharge will be either pumped J..n.to gtfle leachate evaporation impoundment pond {located in WMU F} or fr-is..-will be collected and removed for off-site disposal hauled to a wastewate r treatment facility for treatment. 2.1.5 Pad CompOSition and Dimensions Active composting areas consisting solo!]! ot compacted soils shol/be constrl:JCred stJCl:l that the compacf:ed s9,;l la}'ef /s otstJ#icient thickness to enslKe the integrity of the bottom l foot otcompacred soil from the effects otcomposting opemtions. Facilities that tlse amenclments or additi~'es Rwst ha~le a la}'ef with a permeability ot no greater than 1 x 10' or other standani allowed in writing by the regional board. The Compost Facility pad will be constructed of low permeability compacted native soil. It is anticipated that the compacted native soil wil l provide adequate protection of groundwater. The compost pad area is utilized (i.e .. the amount of area -) based onsized to aocommodate each of the selected composting method and materialstechnologies. The green and wood waste grinding area is approximately 1.56 acres. The material sorting area pad will be up teis approximately 1.07 acres , and the windrow areas are approximately 14.8 acres . The Forward Composting Facility SWT Engineering Report of Composting Site Information -May 2014 z:\projects\aliied waste \forward\resource recovery faci lity\5 yr perm it rvw 2013-14\rcsi 2014\text\se c 2 -revtr .do c