For what it's worth, you're not alone. Almost every landfill operator or composter has experienced this phenomenon. It's called "the perception of odor." Some operators are convinced that such calls come exclusively from chronic complainers and gleefully tell stories about how they temporarily stopped complaints by undertaking, with considerable fanfare, the spraying of their facilities–with plain water. The perception of odor was combated with the perception of "doing something."

Doug Mason, vice president and chief operating officer of Continuum Chemical Company in Houston, TX, has a variation on this classic story: "Continuum products suppress malodors with an encapsulation process that does not rely on fragrances. But occasionally we've had a landfill customer request to have us add a bit of a scent so that his neighbors can detect something there; again, it's just giving these neighbors an impression that the operator is ‘doing something.' And it's ironic that using fragrance in this way or as a masking agent often results in neighbors getting tired of the same floral or similar scent all the time and thus making a different type of complaint. One landfill manager in Pennsylvania told us that they had been fined by the DEQ [Department of Environmental Quality] for disseminating pleasant fragrances."

What Causes Malodors

"We know what causes malodors," continues Mason. "Over 80% of all offensive odors are the result of the presence of just two basic types of chemicals: nitrogenous compounds and sulfur-bearing compounds. In most circumstances, the products that people use contain these elements in structural arrangements that are not odor-causing. However, in other combinations and arrangements, these same chemical elements can be obtrusive with strongly offensive odors.

"In the odor-producing process, organic material is broken down into smaller, volatile molecules. As the microbial decomposition process progresses, the nitrogen and sulfur atoms present in the organic matter are rearranged into smaller molecules that are odiferous. Ammonia is an example of a strong, pungent nitrogenous compound that is found in household cleaning products. It is also the key malodor from urine. Derivatives of ammonia, known as amines, have other characteristic foul smells. For example, simple amines, such as dimethyl amine and trimethyl amine, cause a characteristic ‘fishy' smell.

"Sulfur-based odors come in different types as well. For example, hydrogen sulfide is the odor we associate with automotive catalytic converters, rotten eggs, and landfill gas. Mercaptans are sulfur-bearing chemicals that are used to impart a strong odor to natural gas for safety purposes.

"Such odiferous chemicals are detected as they volatize into gases and are dispersed into the air we breathe. These chemicals stimulate the olfactory glands on our nasal passages that transmit a signal to the brain where detection and recognition of the odor occurs. Our products interrupt this process by converting offensive chemicals to materials having no odor. For foul odors not capable of being converted, an active encapsulation process binds malodorous substances, thereby capturing them and preventing their evaporation."

That's a good scientific description of how malodors are generated and one reasonable approach to how they can be effectively controlled, but it does not explain the perception of odors. Rick Losa of Waste Management, which uses Continuum products on a number of its landfills, believes that odor-suppression systems are useful and beneficial, but he does not discount odor complaints as being frivolous or imaginary. "You can only control so much in an open-air environment like a landfill," he points out, "so odor is a fundamental landfill phenomenon.

"If our landfill gas—recovery system goes down, we will get odor complaints. When the wind shifts, we may get complaints. We find that odor complaints are tied to events such as these, so our neighbors' perceptions of odor cannot be considered imaginary. This is a subjective issue, to be sure, but we certainly can't guarantee that if we put in the very best odor-suppression system, there won't be an odor problem. We have to deal with our neighbors and take their complaints seriously. It's an essential part of operating a landfill today."

The Need to Deal With Perceived Malodors

The penalties for not dealing proactively and effectively with perceived malodors can be very severe today. "Landfill nuisance has become a legal issue now," Losa contends. "People are suing landfill operators, not based on whether they are violating their permits, but based on the allegation that the very nature of a landfill's existence creates a nuisance that justifies some sort of compensation. The suits aren't based on any scientific limits that are being exceeded, and there is no basis established as to what constitutes a litigable nuisance, but these suits are being pursued. And if a landfill has an excessive malodor problem, its case is likely to be much more difficult to defend–even though there are no quantitative odor levels or other criteria established as to what constitutes an odor problem."

The lack of scientific data cuts two ways. While this lack hampers the plaintiff in such a suit, the operator needs good quantitative data to successfully defend a suit. This is equally true in dealing with regulators, says Bob Gaubert of Robert E Gaubert & Associates in Loganville, GA. "You have to get proactive before opposition gets too strong. Otherwise you may end up with community or regulatory action that may even put you out of business. If complaints are directed to your regulatory agency, you may not be able to avoid being put on notice, although if you can show records that indicate you're doing the best you can, your chances are better. But if they come back a second time, you'll probably be facing a lawsuit or a fine, and unless you can prove that you have been taking meaningful corrective steps, there may be a judgment that can go all the way to enforced closure."

That's exactly what happened in Marlborough, MA. A co-composting facility adjacent to the city's wastewater treatment plant caused such severe odor complaints from nearby residents that they formed a neighborhood association and filed a lawsuit against the city. A year later, a superior court issued an injunction that shut down the facility. This created an expensive waste disposal problem for the city, so a year later it solicited bids for a system to co-compost its biosolids. Waste Options of Warwick, RI, was awarded the contract for the co-composting using the city's MSW as the bulking material.

"The neighborhood association didn't want a repeat of the odor problems of the past," recalls Waste Options's Nelson Widell. "They worked with the city to set up an odor advisory committee while the new facility was still under construction. The superior court decision was incorporated into the city's contract with us, so we knew that if our facility produced nuisance odors, the lawsuit would again kick in and we could be shut down immediately. It was a particularly dicey situation for us because this site had a reputation for malodors, and that usually establishes a perception of an odor problem that is difficult to overcome.

"Also, ours was the first composting facility to be built under the Massachusetts DEP's [Department of Environmental Protection's] Draft Guidance and Policy for the Evaluation of Odors at Composting Facilities, which established an emissions limit of five dilutions to threshold at the property line. We met that standard at a cost of $2.5 million, and it is a state-of-the-art facility. However, we were still concerned about the perception of odor possibilities under our contract so we took steps to mitigate that problem too."

A Proactive Program in Marlborough

Waste Options decided upon a proactive campaign to communicate with its neighbors rather than wait for complaints. During the early startup phases, it went directly to the neighbors to make sure they knew what was being done and how it would benefit them. And there certainly were benefits to extol. First, the new facility cut the costs of processing the city's biosolids rather than hauling them 25 mi. out of town to be incinerated. Equally important were the benefits of the recycling program that Waste Options had implemented and was managing at the site. Since the facility went on-line in August 1999, the city's recycling rate has increased from 11% to 65%.

"We had to address the odor issue, of course," Widell says. "We took care to explain to them all the odor-control provisions we were incorporating into the facility design and operation, and we told them of the odor-emissions limits that we had agreed to and that were subsequently to be reflected as guarantees in our contract. We showed them the high-speed roll-up doors in the tipping building, the system of pumping the biosolids underground, the in-vessel digester that kept the composting from releasing odors to the outside, and the biofilter that was itself contained in a building. I'm not sure how much of the technical information these neighbors absorbed, but they seemed impressed that we were doing ‘something' and were guaranteeing its effectiveness."

Building on this proactive beginning, an odor committee was formed, consisting of two members of the community, one from the Public Works Department, one from city council, and one from Waste Options. This gave the community representation in all odor-related issues. In addition, Waste Options set up a hotline and an e-mail address to facilitate rather than impede the receipt of complaints.

"If anyone smells anything, they can contact us by telephone or e-mail without delay," Widell says. "In turn, we are committed to respond immediately. We go to that person's home to verify that the smell is real and that it is being generated by our facility. There is a sewage treatment plant immediately adjacent to our facility, and for a while we were being accused of odors they were generating. Occasionally the odor problem proves to be ours, but almost always it results from human error, such as a fan left off or a door left ajar. Once we have identified such an odor problem, the correction needed is clear-cut, and we make it immediately.

"Today the complaints are much less frequent; for one thing, our neighbors now can tell the difference between odors generated by the sewage and ours, and we seem to be winning over even those who were the most vociferous opponents of establishing this facility in the first place. In fact, we actually got a standing ovation at a neighborhood open house recently, and in this fall's elections, every one of the council members–including those who had voted against the project initially–supported our operations as being a very good deal for the city."

Overcoming a Reputation

It should come as no surprise that most people assume a landfill is smelly and will create a malodor nuisance in the community. And as Joe Stockbridge of the Town of Colonie, NY, found out firsthand, "Once you're tagged as an odor source, you're it. It doesn't seem to matter how bad the odor is or what its source really is. The odors from every hot-tar roof installation are attributed to you. To combat this misconception in our town, we had to mount quite a campaign.

"First there was the appearance issue. If people see litter around a landfill, it reinforces their dislike for landfills and reminds them that they are living near one. We don't let this happen. Our landfill is landscaped like a park, and we don't tolerate litter. We've found that if you attend to aesthetic issues, you'll have fewer problems with neighbors. That's not all, of course. We make every effort to get people to visit our landfill so that they can see what we are doing. We have 50 to 75 tours each year, including schoolchildren tours. If anyone expresses an interest in us, positive or negative, we send them letters that tell them what we are doing and invite them to ‘walk the site.'

"We also have an odor-control committee, made up largely of residents. Not only do we report our activities to this committee, we provide them with data, including consultant reports, complaints, and complaint resolution records. We want them to feel that they are a part of our odor-control management team. And slowly but surely, it helps. At least we're getting fewer hot-tar roof complaints. Of course, we have to continue to be diligent in looking for odors and mitigating them where we can, and we have to show our neighbors that we're doing our job professionally and well. We've found that with a program like this you can earn their grudging approval. Still, they're never going to love the fact that you're there; after all, you're still a landfill."

This effort is not restricted strictly to municipally operated landfills. Losa says Waste Management also invests time and effort in communicating with residents who live near the company's landfills. Waste Management encourages organized homeowner groups to work with landfill management. "We hold meetings, brief them about upcoming events such as the start of a new cell, and make our monitoring reports available to them," Losa explains. "Thus, they have close and personal access to us and our records–and we have access, through them, to the community.

"This doesn't mean that these resident groups have to support your landfill operations. Instead, it means that you have the ability to communicate with each other constructively, rather than go to court. And once they have accepted the fact that the landfill is going to operate in their neighborhood, they usually come to the conclusion that if they want their concerns heard, they need to have a constructive way to communicate with the landfill operator on an ongoing basis."

A Comprehensive Program

Bob Gaubert, when he headed Odor Control Technology (OCT), devised a program that his company recommended to landfill operator customers as a complement to OCT odor-suppression products. The program began with a physical survey of the landfill or transfer station facility to gather physical data that would affect a determination of exactly what that operator's plan of action should be.

"These surveys almost always led to a conclusion that community action was needed," Gaubert recalls. "So then we recommended that they should proceed to take measurements. The first ‘measurement' was to take a sniff test every day at specific locations at the same time and chart the results on a scale of 1 to 5–with 5 being the most malodorous. Then the operator was advised to establish a meteorological station to gather and evaluate wind velocity, wind direction, moisture, and temperature on a methodical basis for various times of day and year. By integrating the sniff data with the weather data, the operator would begin to develop a profile to evaluate and understand complaints.

"We asked the operator to be very proactive in investigating each complaint by visiting the site and walking around with the resident to typify and verify the intensity of the stink, if any, and to identify the extent of the malodor. This personal data gathering, we found, had a valuable side effect. Apparently, just because the operator showed that he cared by making immediate responsive visits, the subsequent complaint level would drop by as much as 50%. We also had them log in whether this was the first time that resident had made a complaint. Statistically there is an inverse correlation between the validity of the complaint and the number of times a given neighbor complains. We recommended to the operators that they take new complaints very seriously."

Of course, the operator would return with potentially valuable data from these investigative visits. He could correlate these data with the meteorological data and the log of what was happening at just the time of the initial complaint. (Was gas being flared then? Was a pile being turned? Did a mechanical system go down at that time?) Not only might this pinpoint the cause of the odor, but it would also enable him to build a profile of meteorological factors that would be useful in modeling the probable plume dispersion that would be experienced under future conditions of that kind.

"Some of these factors weren't immediately obvious," Gaubert points out. "For example, if there are no clouds or no high temperature on a given day, odor compounds will go straight up into the atmosphere, and neighbors won't smell the malodor even if the wind is in their direction. Conversely, a diurnal change or a high moisture content in the atmosphere will create a lower ceiling, so the operator will have to take extra measures to make sure odors don't float over to neighboring residences.

"Based on this model, the operator will be in a position to take proactive corrective action if the same profile of conditions recurs. He can tweak his operations, perhaps delaying flare operations, changing the pretreatment that day, or increasing or redirecting the spraying of his odor-neutralization system. And with complete records of what he did and why he did it, the operator is in a strong position to contend with regulatory investigations or lawsuits."

The phenomenon of perceived odors is difficult to address, primarily because your facility has its own conditions that are different from those of every other facility. With no formula solution available, an operator must combine detective work with science and psychology. It's frustrating, but it goes with the territory.

Frequent contributor Charles D. Bader is with Dateline II Communications in Los Angeles, CA.