Appendices to Integrated Resources & Solid Waste Management Plan - Dec 2009

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HAWAf COUNTY MECHANICAL - BIOLOGICAL TREATMENT FACILITY CONCEPTUAL DESIGN Conceptual Design Basis Design and performance criteria are specific measurable parameters that provide guidance for the design of a facility. The design and performance criteria contained in this section have been developed based on experience at other MBT and organic waste processing facilities in North America, as well as industry "best management practices'. In addition to the criteria, a set of functional requirements have also been developed for the two MBT facilities. These are intended to identify specific facility components that will be required, the role of each, and any associated design requirements. Design and Performance Criteria Design Life Based on the current and projected quantities of these feedstocks and the rate at which solid waste management technologies are advancing, a minimum design life of twenty years is recommended for the major components of the facilities, including buildings. Secondary components, including mobile equipment and some mechanical pre- and post - processing equipment, will have a shorter lifespan and will require replacement during the twenty year period. For example, mobile equipment used in MBT plants can be expected to have a lifespan of 5 to 7 years, and processing equipment from 5 to 10 years. The lifespan of equipment in Hawaii County will also be affected by volcanic emissions (sulfuric acid rain), particularly with the high rainfall experienced in East Hawaii (approximately 135 inches per year). Feedstocks The two facilities would be expected to accept and process MMSW from both residential and commercial sources. This feedstock will contain a mixture of organic and non - organic materials, and separation of these materials within the facility by various mechanical processes would be required. It is expected that materials would be received in loose form as well as contained in non - biodegradable plastic bags. In addition to the MMSW stream, it has been assumed that the facilities would accept and process green waste that is currently being mulched or composted through other operations on the island. The facilities would not be designed to accept and process white goods, construction and demolition wastes, household hazardous waste or special wastes. These would be addressed by other waste programs implemented by the County or through Extended Producer Responsibility programs. Biosolids from wastewater treatment plants could also be mixed with MSW and processed at the MBT plants. The biosolids provide a convenient source of both nutrients and moisture which will aid the biological degradation process, and reduce the amount of moisture that needs to be added to the feedstocks.