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ORANGE WATER AND SEWER AUTHORITY A public, non-profit agency providing water, sewer and reclaimed water services to the Carrboro- Chapel Hill communio). EXECUTIVE SUMMARY OWASA has evaluated several options to improve and optimize recycling the biosolids produced during the treatment of wastewater at the Mason Farm Wastewater Treatment Plant (WWTP). This draft Biosolids Management Report Part 2 presents the results of that evaluation, and focuses primarily on options that use existing biosolids treatment processes at the WWTP. As agreed to by the Board of Directors, this evaluation does not include options that would require design and construction of new, major biosolids treatment systems either independently or in cooperation with other parties. Options have been evaluated against social, environmental, and financial objectives which have been previously agreed to by the Board of Directors, but for which no relative ranking or weighting has been assigned. An additional objective — consideration of impacts on OWASA employees — is included for consideration. Key findings from the evaluation are: 1. There is no single alternative that outperforms all other options across all objectives; therefore, the final decision as to the preferred option will depend on how the Board of Directors weighs the different objectives. 2. Based on the assumptions used for this analysis, the annual operating and maintenance costs of all of the options evaluated are within about 17% (about $150,000 difference between the highest and lowest cost options) of one another. Capital equipment and capital improvements costs associated with the different options have a much greater range of variation, with the lowest option costing $380,000 and the highest costing about $1.8 million over the 20 -year planning period. (This is about 1% or less of the projected total Capital Improvements Program costs for the next twenty years.) 3. Options involving the land application of liquid biosolids are more transport- intensive, and involve more risk of vehicle accidents, spills, and improper application of biosolids. They also have greater uncertainty regarding their long -term viability. Options involving land application by OWASA are more labor intensive. 4. Options involving greater dewatering will pose greater challenges for the treatment of wastewater, especially as plant flows approach the design capacity of the WWTP. 5. Land application of liquid biosolids maximizes the value to farmers, while application of dewatered biosolids has considerably lower value to farmers due to reduced nutrient and moisture content. 400 Jones Ferry Road Equal Opportunity Employer Voice (919) 968-4421 Carrboro, NC 27510 -2001 Printed on Recycled Paper « « «.o«asa.org 1.4