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

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HAWAIH COUNTY MECHANICAL - BIOLOGICAL TREATMENT FACILITY CONCEPTUAL DESIGN neighbors complained about odors emanating from the facility. There are many other examples of facilities that have been shut down over the years in North America because of odor complaints. Proper siting is important to reduce impacts to users and adjacent property owners. Although a well- constructed and well- operated organic waste facility will not be odor -free, it should not produce offensive odors. Some odor control techniques, such as good housekeeping and eliminating sources of odor like wet feedstocks and /or stagnant water, cost very little and can be extremely effective in preventing odor production. Sound management practices, careful site selection, and communication with neighbours may be the best and least expensive means of preventing odor complaints. Every facility operator should know and understand the sources of odor at their facility, and develop proactive strategies to manage them. This would include understanding the types of odors the facility could potentially produce, site and environmental conditions which lead to odor release, engineering controls and operating practices that reduce odor potential, and the potential impacts fugitive odors may have on neighboring land uses. Because most anaerobic digestion and composting facilities have experienced odor problems at some point in their history, one of the most effective ways of developing a strategy is to incorporate lessons learned based on experience at similar facilities. The exchange of verified technical information on emissions before and after process modifications is valuable in identifying and selecting control methods. Casually observed odor control results that are not backed by supportive technical data should not be used as the sole basis for justifying corrective actions. Generally, enclosed or in- vessel systems have a much greater ability to capture odorous emissions and treat them prior to release. There are a number of available methods to treat odors from composting facilities including wet scrubbers, biofiltration, and carbon adsorption. The choice of which treatment methods are appropriate is dependent on process air volumes, types of odor compounds generated, and airborne gas concentrations both on site and at properties adjacent to the facility. "Fugitive odors" is a term that is used to describe airborne gas emissions (odors) that escape from point sources at a facility and migrate to surrounding areas. They can include odors from leachate spills, stagnant water, and leakage of odorous process air from tanks and vessels, from feedstock stockpiles, and from open or faulty overhead doors. Because they tend to be smaller in volume and concentration, and more dispersed throughout a facility, it is often more difficult to manage these fugitive odors than to collect and manage odorous process gases. Maintenance Within the composting industry, MBT facilities are known as having technically challenging working environments. One of the primary technical challenges is corrosion resulting from sustained exposure of equipment and infrastructure to humidity and process gases, and biological corrosion processes. Concrete and stainless steel buildings have been demonstrated to be the most durable types of structures for this type of corrosive environment. However, the initial capital costs associated with these types of structures are not acceptable to some Owners. For steel or other metal structures, a range of coating types (e.g., galvanizing, epoxy, foam) and building liner systems have been tried with moderate success. As a compromise between initial capital cost and long -term durability, many newer facilities combine negative aeration and