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07
City of Pleasanton
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CITY CLERK
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AGENDA PACKETS
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2015
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110315
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07
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10/28/2015 3:18:32 PM
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CITY CLERK
CITY CLERK - TYPE
AGENDA REPORT
DOCUMENT DATE
11/3/2015
DESTRUCT DATE
15Y
DOCUMENT NO
07
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BACKGROUND <br /> Biosolids is the residual organic material remaining after the treatment of wastewater. <br /> Biosolids go through anaerobic digestion treatment in wastewater treatment plants, to <br /> reduce the biosolids, and to stabilize the organic material which becomes odor and <br /> pathogen free. A by-product of this process is the production of methane gas. The <br /> methane gas is then used in the wastewater treatment plant for onsite power <br /> generation. The biosolids are then "dewatered" prior to disposal. <br /> Some facilities across the country dispose of the biosolids through incineration, co- <br /> composting with vegetation, materials or transport to landfills. However the vast <br /> majority of facilities spread the biosolids on agricultural land. In California most of the <br /> biosolids are transported into rural counties for disposal although some southern <br /> California agencies transport biosolids by rail to Nevada or Arizona. <br /> In most locations, biosolids are being used to enrich farm lands and reduce fertilizer <br /> use. However, in the late 90's many rural California counties began prohibiting the <br /> import of biosolids from outside the county. Many landfills are also putting a limit on the <br /> amount of biosolids that will be accepted limiting the use to being mixed with dirt for <br /> daily cover. The primary reason for the prohibition was not related to health and safety. <br /> In some locations land was taken out of agricultural production and simply became a <br /> disposal site which was declared incompatible with county planning regulations. The <br /> primary reason for the bans was "environmental justice". Rural counties did not want to <br /> become the dumping ground for urban areas. <br /> Theoretically, biosolids have adequate remaining organic content to be an energy <br /> source. However, after treatment and dewatering biosolids retain 95% water by weight. <br /> The water is "bound" not "free flowing" and is difficult and energy intensive to remove. <br /> Because of concerns about the energy future of the world, over the last 20 years <br /> substantial research has gone into development of process to use biosolids to produce <br /> renewable energy, particularly in Europe. <br /> Dublin San Ramon Services District ("District") does not dewater biosolids after <br /> anaerobic digestion but places the biosolids in stabilization basins. The biosolids <br /> remain in the basins a minimum of four years for further stabilization and to obtain an <br /> EPA rating of "Class A" which results in no restrictions for land application. The <br /> biosolids are then applied to the land adjacent to the stabilization basins. The District <br /> facilities for processing biosolids are north of the treatment plant site across Stoneridge <br /> Drive. <br /> A number of Bay Area entities, faced with the loss of disposal sites, began working <br /> together to determine the feasibility of emerging "waste to energy" technologies to <br /> process biosolids locally, produce renewable net energy, reduce production of <br /> greenhouse gases and reduce the carbon foot print of biosolids disposal. DSRSD was <br /> one of the founding members in the 90's of a "Coalition" to investigate implementation of <br /> a regional processing facility. <br /> The DSRSD biosolids facilities are very low cost compared to most agencies and have <br /> an estimated 40-50 year life. However, prudent biosolids management should have a <br /> backup option for disposal in case of an operational issue or changes in regulations. In <br /> Page 2 of 5 <br />
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