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Report of Composting Site Information <br />Tracy Material Recovery and Transfer Facility <br />30703 S. MacArthur Drive, Tracy, Ca. 95377 <br />automatically controlled per operator -chosen set -points. The system exhaust air is <br />scrubbed in a biofilter constructed of wood chips in the case of negative aeration, and <br />passes through the layer of finished compost and/or compost overs in the case of <br />positive aeration. The aeration rates can be set very low to conserve moisture and fan <br />power, without releasing odors. Prior to removing the cover the aeration is increased to <br />lower temperatures and raise oxygen levels; this greatly diminishes the potential for <br />odor releases. The use of an aeration floor facilitates implementation of aerated static <br />piles. <br />Similarly with the elongated and compressed windrows, two types of geometries are <br />available for the aerated static pile; elongated and extended. <br />• Elongated Aerated Static Pile <br />For the elongated aerated static pile, the material is formed into trapezoidal -shaped <br />piles of approximately 30 feet wide, 15 feet high, and 70 feet in length. Piles are <br />separated by a narrow access area to facilitate loading, monitoring, watering, moving, <br />and turning. Elongated piles may also be formed within concrete -walled bunkers of <br />similar size for easier materials management. <br />• Extended Aerated Pile <br />To make more effective use of available space, another pile configuration has been <br />developed called the extended aerated pile. Studies indicate that the area required for <br />an extended pile is about 50% less than that for an elongated static pile. Extended piles <br />consist of individual cells that are stacked against each other. Cells of new feedstock <br />are constructed in one pile, and cells of nearing mature compost are placed in other <br />piles. Extended aerated static piles also increase the emissions control achieved with a <br />layer of finished compost as the adjacent cells of feedstock support the finished cover <br />layer of the adjoining cell, minimizing sloughing of the compost layer. <br />Cover Systems <br />The synthetic ASP cover is designed with straps for handling and securing it and may <br />be placed and removed manually or with mechanized cover -rollers. The cover may be <br />held in place by the aeration system which operates with negative suction that holds it <br />firm against the pile or, in the case of positive aeration, use of perimeter weight at the <br />base of each ASP. The impermeable cover over the ASP eliminates rain percolating <br />through the pile and therefore reduces the total nutrient load found in the facility run-off. <br />Proper grading of the site is maintained to limit intrusion of storm water around the <br />"sealed" edge of the cover. <br />Alternatively, a layer of finished compost or compost overs with a minimum thickness of <br />6 inches can be used to minimize storm water infiltration due to its absorptive capacity, <br />and reduce air emissions by oxidizing gaseous compounds. The compost cover layer is <br />incorporated into the feedstock when the pile is turned. With either a compost cover or <br />an impermeable plastic cover, the system could potentially be operated under either <br />negative or positive pressure depending upon the type of synthetic cover technology or <br />0 which phase of composting (active or curing) a particular batch is undergoing. <br />14 <br />