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more effectively bind solids, release water,and keep smaller particles from penetrating and plugging the sand bed. U.S. EPA recommends that waste streams be thickened to at least 3%. Currently,the City waste stream is approximately 1%-2%,thus requires additional processing to increase solids concentration and release water. Specifically, U.S. EPA data shows that drying beds can produce waste stream loading rate of 12-10 lbs/s.f./year from unconditioned solids. However,chemically conditioning the waste stream can increase loading rates 50 to 100 percent. Drying Bed Design and Operation The City anticipates use of the drying beds during the warmer months(i.e.April—October). Winter months do not provide conducive drying conditions, due to rain and low temperatures. During the winter months,solids production is greatly reduced due to low water demands,thus solids can be held in the backwash recovery process during this time. During warmer months,the filter backwash waste stream will be conditioned (thickened) and released onto the drying beds. The waste stream will be allowed to dry to approximately 25%solids before removal for final disposal. 7,t4in, According to data,the City will produce approximately 40,000 lbs of solids at full water treatment production. Assuming the solids are conditioned (per U.S. EPA recommendations),the drying bed area required is approximately 1,600 square feet,or40' x40'. However, bed area will be increased to V� account for bed rotation. In addition, an area will be reserved for drying of leachate. Hence,the total area for solids processing is approximately 100'x 100'. Bed design will consist of four(4) individual cells approximately 15'wide x 60' long. Each cell will have underdrains embedded in gravel and covered with 8—10 inches of sand. Two (2) evaporation ponds will collect leachate from the drying beds. All units (drying beds and evaporation ponds)will be constructed with concrete floors to avoid leachate percolation. Prior to the onset of cooler months,the beds will be cleaned of all solids,thereby allowing rain to drain from the beds to the detention basin located on site. -" MWS 1- siktLe,7 wll�,4-e_ Pre Design (60 J ekk At this time,the City is testing various chemical dewatering processes to determine which chemical or combination of chemicals that will result in the best sludge drying. Once this is determined, a final design (process and drying beds)will be developed.