BioCycle Magazine

Fitting Into the Neighborhood: Operating by Progressive Odor Management Plan

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Courtesy of Courtesy of BioCycle Magazine

 Operating by Progressive Odor Management Plan

Why would anyone build an $11 million composting facility designed to process an average of 130 tons/day of feedstocks less than one mile from luxury homes, a new high school, a golf course, fast food restaurants, a grocery store, and in an area with a vivid memory of a compost site that impacted the neighborhood and shut down due to odor problems? The answer is, unless you apply organic residuals directly to agricultural land, travel increases product costs, not product value. Being so close to generators gives them convenient access to the site, and there are ready markets for high value end products. However, to operate in such a neighborhood requires a hefty investment in a facility, good neighbor relations, and an effective and responsive odor management plan.

Solid waste management activities predate the residential or commercial land development surrounding this site in Pierce County, Washington, operated by Land Recovery, Inc. (LRI). Initially, it was home to LRI’s Hidden Valley Landfill, then a transfer station. (The landfill closed in January, 2000.) Expansion plans called for construction of the composting facility on 20 acres adjacent to the transfer station. We wanted to move beyond just yard trimmings and also handle pre- and postconsumer food residuals, manures, biosolids and other industrial and agricultural feedstocks. Since the plant, which LRI calls the “Compost Factory,” began operating in the fall of 1999, it has been handling peaks of 250 tons/day.

It was decided from the outset to build an enclosed composting facility (see “Investing Upfront In A Compost Factory,” November, 1999). Given the site’s sensitivity, odor control was critical to the plant’s design and regulator and neighbor acceptance. One step taken early on in the planning and permitting process was to invite neighbors to be a part of it.

We found people who are interested in their community and its health, especially those people successful in shutting down the other composting facility. We offered them convenient times and places to meet, invited their community organization to come talk with us, and asked for additional contacts.

We told people the composting operation was going to smell once in a while, for example, during stagnant air conditions. If we had said it is never going to be a problem, we might as well have given up, packed it in and not spent a single penny.

We make a point of interacting with the community. We provide services and end products that are worthwhile to them. Furthermore, we visit the neighborhoods weekly, monthly or whatever it takes, especially during the odorous season, and watch our site from their perspective. You will really get an education that way, and keep open the lines of communication. We also learned to never blame others for your odors. Take the blame. Assume it is you until it is proven differently.

Our facility had 13 notices from neighbors last year that they did not like how we smelled. Two of those neighbors complained multiple times and each time, we went out and responded. They are happy neighbors now because the problems we created were resolved quickly.

Another key to fitting into a neighborhood is designing away the known impacts. The enclosed LRI facility is based on simple construction, effective process aeration control, and flexible off-the-shelf equipment with redundancy of essential components (from grinders and turners to blowers and two biofilters comprising over an acre of land area). But from our neighbors’ — and the regulators’ — point of view, the primary objective of the facility is to control odors.


LRI has a Progressive Odor Management Plan incorporated into its permits. The plan provides methods for operators and regulators to respond quickly and effectively to problems, spelling out progressive steps to take until the problem is fixed. Essentially, the plan puts our verbal commitments to the neighborhood in a legal document (the permit).

This plan — adapted for our use from the U.S. Composting Council’s Regulatory Committee’s recommendation for facilities to develop a progressive odor management plan — consists of three primary components: Prevention, assuring proper operation of the composting system as designed and improved; Accountability, which outlines the expected interactions among operators, regulators, and neighbors that provide procedures for identification, notification and resolution of malodors; and Progression, a series of escalating operational adjustments, feedstock controls, and factory upgrades designed to stop an unacceptable condition as quickly as possible. It is designed to be approached sequentially and quickly until the problem is resolved.


Key to prevention is proper operation of the composting system and having the capability to capture and treat odorous emissions. At LRI’s facility, our prevention plan focuses on five primary components:

Aeration: The aeration design is based on delivering the optimum amount of air to the composting mass through the in-floor aeration system and the reestablishment of porosity through turning. During turning, the operator must check for air flow through each orifice in the floor before covering it with compost, assure blower operation for that zone is in positive mode, and assure continuous blower operation and delivery of air after turning. The oxygen content of the composting mass is checked if malodors emerge. If oxygen content drops below 15 percent, the operator increases aeration rates, adds bulking agent, and/or turns materials to reestablish porosity.

Control Process Variables: Operators are trained to understand the influence of moisture content, particle size distribution, pile height and energy content of the composting mass on the rate of composting, how those variables change during composting, and the facility’s ability to meet the aeration needs consistently throughout the composting mass during those dynamic changes. Each of these parameters can be controlled at different points in the process. During mixing of feedstocks, low energy materials such as wood residuals are blended with high energy materials to provide an initial balanced energy level. Operators assure there is homogeneous mixing of feedstocks and adequate bulking materials to maintain porosity. Moisture levels are adjusted to not exceed 60 percent at any time (averaging 53 percent during active phases); during stabilization and/or curing, levels are kept at 40 to 50 percent.

Housekeeping: Cleanup of the facility both inside and out reduces the likelihood of odor release. Daily sweeping or scraping, and on time processing of fresh feedstocks, provides the easiest and most effective measures to reduce odors. Operators must put active compostable materials under aeration control within eight hours of receipt, and have them mixed and placed on aeration beds or in bins within 18 hours of receipt. (The LRI site has 15 NaturTech bins that currently are used to test composting of a residual before it is handled on a regular basis.)

Biofilter Management: There are four biofilters that take up over one acre in area. Operators monitor moisture content weekly and maintain levels above 45 percent. They check for even air flow and back pressure across each biofilter bed. Temperatures cannot exceed 110°F. All air lines collecting and delivering air to the biofilters must be free flowing.

Detection and Response: The four previous components have been proven to prevent nuisance odors. However, because odors by their nature are subjective, and community norms about what is acceptable evolve and change, the last component of prevention is to have a detection and response team. At the compost facility, operators are required to identify the source of, and quickly respond to, potential nuisance odor conditions within the facility, document the problem as well as how it was or wasn’t resolved in the log book, and notify facility managers as soon as possible. Facility managers must verify whether the odor condition has been resolved and notify the local regulatory authority, the Tacoma/Pierce County Health Department (TPCHD), if it has not.


Odors that operators and management deem as acceptable may not be acceptable to health department regulators, the regional Puget Sound Air Pollution Control Agency (PSAPCA), or neighbors. The Accountability and Progression sections of the Progressive Odor Management Plan are designed to educate operators and management about the community norm, and how well the facility is meeting its odor control commitments. These sections also force odor control procedures to be updated and maintained. Given the risk of having forced reductions in the types and amounts of feedstocks accepted, or closure of the site, it is obviously in the best interest of the operators, management and owners to avoid nuisance odors.

The accountability section has six components:

Corporate Commitment: LRI made a commitment to resolve odors quickly before the facility was built. That commitment essentially became part of our operating permit. One underlying premise is that we had to accept community norms and empower the neighbors to change what we do.

The accountability system when odor complaints arise must be flexible, fair, and enforceable. Our odor management plan creates a structure that incorporates those characteristics. The operator responds to complaints in predetermined steps or phases, with each step being progressively more demanding. If one phase is not deemed to be effective, the next remedial phase is implemented, and so on until either the problem is solved, or formal regulatory enforcement occurs. If the change is effective, the operators maintain that change, and if further problems emerge at a later time, the process of remediation begins again. If Land Recovery fails to make progress and manage odors to a reasonable level, regulations exist under state laws that impose fines and/or closure.

 Community Norms: Except for extreme cases, odor issues elude objective and precise definition and, therefore, objective management or enforcement. The odor plan is designed to identify and deal with commonly accepted norms of the community to whether an odor is truly objectionable.

Odor Description: Composting facility odors have two basic aspects, character and strength. Odor character, sometimes referred to as “hedonic tone,” is particularly subjective. Odor strength, which often is determined by odor panels and expressed in terms of numeric “dilutions to threshold” (D/T) value, is generally regarded as more objective. Depending on the constitution of the odor panel, however, odor strength assessments also can be subjective to a significant degree. This odor management plan attempts to take both aspects, particularly odor characterization, into account.

Reporting and Responding to Problems: Offensive odors can be identified in many ways for the purpose of this plan. Ones detected by operators or managers during site walks and facility inspections, as well as those of visiting health or air quality officials, are relayed to the plant manager, and to a TPCHD official as soon as the problem is identified. People complaining about odors are asked to identify the location and time of day of the odor occurrence, and allow either the plant manger or the health official to visit their site and verify the source and characteristic of the odor as being one from the composting facility. A “trained nose” familiar with the types and characteristics of the different odors generated at the compost facility also is sent as soon as possible to the location where the odors were noticed. This provides the fastest and most useful information so that odors are immediately identified or corroborated and actions can be initiated to correct the problem.

Complainants are invited to visit the site with either or both the facility manager and the health official to allow them to see and smell the facility’s operations and more accurately provide feedback during future complaints.

Document the situation: The odor’s location, characteristics, the time and date, and existing meteorological conditions and suspected specific source are written down immediately, as is any information that indicates relative strength compared to other events, and when during the day the odors are noticed.

Baseline Odor Panel: An odor analysis was performed by consultants for the composting facility during the final phases of startup to provide qualitative and quantitative baselines for future performance of the plant as well as nose training for those involved with the facility. The baseline included pre- and post-biofilter odors, building inlets from the receiving area, and the curing piles. Unfortunately, downwind and upwind odors at the facility’s property line or other expected impact areas during worst case meteorological conditions, as well as other suspected sources such as the solid waste transfer station located on the same site as the composting plant, were not sampled. The baseline odor analysis can be done by a professional odor panel to get accurate dilutions to threshold numbers or by a panel that includes health officials, plant operators and managers and neighbors. Draeger tube measurements for expected odor compounds were taken at the same time to help correlate them to the odor panels results and insights. The baseline will be a useful tool to evaluate changes over time, the impact from adding other feedstocks or to compare improvements to the facility.


The presence of nuisance odors originating from the facility — identified during operator, manager or regulator site inspection, or a neighbor complaint verified by a trained nose — initiates the first of four levels of action that take place successively until the odor conditions external to the property are acceptable to the local health department or regional air quality authority. Levels one though four are actually part of our operating requirements, thus we are legally bound to comply.

Level One: Level One is self-odor inspection and correction. Each of the operational aspects that impact odor generation and control are evaluated by operating personnel as to their contribution to the offensive odor. The primary odor generating operating condition will be corrected or adjusted using the existing process management tools described in the plan of operation. The adjustments will be made as quickly as functionally possible. The majority of these corrections, such as lowering heights of some piles, reblending materials, increasing oxygen or reducing temperatures, can occur within 24 hours.

Corrections may take longer if a pipeline needs to be reconstructed, a part has to be ordered, or a replacement piece of equipment has to be obtained. These corrections take priority over other operations. Corrections that take longer than 24 hours will be improved upon and anticipated to reduce their remediation time if they occur again. Corrections that resolve odors will be maintained and emphasized during ongoing operations.

Level Two: Level Two is to change the operating procedures. If the odors are still persisting and we have done the best we can with the tools available, the company and regulators evaluate those improper conditions together as a team, and outline new procedures and handling methods. These procedures are implemented as quickly as possible — usually within a week. That might mean totally revamping the height of all piles in the building. Any new equipment needed is ordered on “rush.” Changes that reduce odors are adopted into the plan of operation and maintained. Then we go back to a Level One mode of operation.

Level Three: Level Three involves restriction of feedstocks. If the odors are still a problem, and are attributed to certain feedstocks handled at the facility, those feedstocks will be suspended from acceptance in large volumes until changes in operations or handling prove, through experimentation (preferably in the enclosed compost bins), to create acceptable odor conditions. If the experimentation works, those methods will become a condition of acceptance for that feedstock in large quantities again. If all materials being composted are generating the unreasonable odors, or if Land Recovery wishes to substantially change the facility to resolve the odor problems for the omitted feedstocks, then Level Four will be entered into. Finally, we always have a backup plan, which is to landfill the problematic feedstock until (and if) we can handle it without odor problems.

Odor Identification and Response Prior to Level Four: Because the fourth level of remediation most likely will impact ongoing operations significantly, good planning and establishment of benchmarks need to occur before going to that level. Odor complaints are now approached more formally. The goal of regulators, neighbors and facility operators is to clearly identify what specific odor compounds are causing the problems and under what conditions, frequency and strength they occur. If this need arises, LRI will hire compost management experts to observe operations, propose process modification options, and perform air sampling and evaluation.

Odor panels (comprised either of professionals or local individuals) can be convened to characterize and quantify the odors. If necessary, odor dispersion modeling will be used to project effectiveness of changes.

The results of the odor panel testing will help determine what levels of odor may be acceptable by both strength and characteristic. The consultant will take that information and evaluate the effectiveness of potential remediation actions — including the list of potential facility improvements outlined in Level Four — to resolve the odor problem. The health department and Land Recovery must agree upon the course of action. LRI will provide all interested parties the results of the research and the proposed remediation to the project.

Level Four: Level Four is basically retrofitting. If the odors are still a problem, and are attributed to the lack or adequacy of the structures, equipment or air treatment methods, physical changes will be made to the composting facility. The appropriate changes will be identified and evaluated by compost odor management experts. Approval from the regulatory agencies will be attained. A schedule for implementing these changes will be developed with the regulatory agency and the community, allowing for normal permitting and construction timelines. Ongoing operations during this process should not interfere with the construction related to corrections. Once fully implemented, the effectiveness of the corrections will be evaluated.

Examples of possible changes include: Addition of exhaust fan(s) to increase negative pressure in the building; Adjustments to size and media of biofilter; Provision of cover and dispersion fan system for the biofilters; Addition of vertical dispersion fans installed in the roof of the cure/store area; and Enclosure of the cure/store area.

Once the changes are in place, normal operations are begun again and we start back on Level One. It never ends. The procedures are repeated as necessary to satisfy regulators that odors are managed appropriately and do not unreasonably impact the use and enjoyment of neighboring properties. Since the plant started operating, we have been at Levels One and Two. We have had to make some repairs, e.g. to seal the water lines that collect leachate from the building, and institute some changes in operating procedure in our curing building.


While capital costs are high for this facility, operational costs are low. Trucking is almost nonexistent, power comes from the closed landfill’s gas, and the existing scales, leachate pretreatment plant and maintenance support are all available. As long as we keep substantially improving and changing our operations and facility to improve odors, we will be able to continue composting and will not be shut down. This is the agreement in the permit. If we balk at any needed improvement, we will be shut down. And that is something we cannot afford.

Any facility that creates an odor nuisance for its neighbors likely will go through similar events and consequences as those described in the Progressive Odor Management Plan. The difference is that having the plan enables the processor to respond to those odors, and significantly reduces the political pressure for being shut down. And, as we all know, the politics of odors are very strong indeed.

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