The City of Columbia, MO’s Solid Waste Utility: At the Cutting Edge of Waste and Recycling

Front loading refuse truck

Establishing itself as a full-service operation, the City of Columbia’s Solid Waste Utility handles not only collection, but also recycling, an MRF, a compost facility, a transitioning bioreactor landfill and works with a community volunteer network that helps with waste reduction activities.

Situated between St. Louis and Kansas City, the city of Columbia, MO’s Solid Waste Utility, which began service in the early 1970s, has established itself as a full-service waste and recycling operation that includes residential and commercial collection, a Material Recovery Facility (MRF), a bioreactor landfill, household hazardous waste collection and much more. As a part of the Public Works Department within the city, the Utility encompasses a staff of 125, serves a population of approximately 110,000 and operates about 45 collection trucks any given day, including backups. Because Columbia is home to the University of Missouri, the Solid Waste Utility deals with many unique waste situations. In turn, they have created an array of components to efficiently take each part of the operation and streamline it into smooth working order.

Side loading recycling truck

Residential and Commercial Trash and Recycling Collection

In addition to the existing residential trash pickup that began in the early 1970s, the Utility started a curbside recycling program in 1986 after a successful pilot program the prior year. Beginning with pickup once a month, a bi-monthly system was implemented in 1992, the same year as the Missouri State law passed banning yard waste and certain other materials like tires, used motor oil and several major appliances from Missouri landfills. “At that point recycling materials had to be segregated into cardboard, plastic milk jugs, cans, etc. and residents would set each material out separately—it was very manually intensive,” says Cynthia Mitchell, the city’s Solid Waste Utility Manager.

“Then, in 1998, we rolled out the blue bag program citywide as a dual-stream, weekly collection system. The city provides blue bags for residents to place their co-mingled containers. Fiberous materials, such as cardboard or newspaper are collected in a box or paper bag. This program helped eliminate people’s confusion about where to put recyclables.” While vouchers for 18 blue recycle bags are given out three times per year—in the spring, early fall and the end of the year, extras are available upon request. Residents also receive vouchers for 25 black trash bags three times per year and can use any other trash bag if they need additional.

There are also 12 recycling drop-off points around the city where people can take their material if they don’t have city curbside collection or if they want to get rid of recycling material between collection days.Mitchell explains that the Utility uses trash and recycling bags instead of containers because, “Over the years, the goal has been a “clean curb approach”.About a year ago we investigated converting from bags to roll carts, but the public resisted so much that the council voted to not move forward with the pilot program. However, a volume-based fee structure is still in evaluation so roll-carts as well as other pay as you throw options such as pay-by-the-bag are under consideration.”

This would address one of the problems that the Utility faces. “I think one of the largest battles of residential collection here is the unlimited amount that can be put out because it causes a lot of employee injury since they collect the trash manually. This is especially challenging during the time that the University of Missouri student population is moving in or out of student housing areas,” says Mitchell. Twice per year, it becomes hazardous for the employees because under the current rate structure, residential customers may put out an unlimited, heavy amount of bags or furniture that has to be lifted into the truck, causing back strains and other related injuries.

Workers could be on one street that might typically take 10 to 15 minutes for more than hour during move-in/move-out times. Even though guidelines on setout times and correct packaging are in place, it is difficult to make the students aware of them, so the Utility started to work on reinforcing the rules this past fall. “There is an ordinance that says to place trash in a disposable container or bag and that has either been disregarded or they don’t know about it. We also have an ordinance for placing trash out on the curb early—if trash is putout anytime before 4 pm the day before, we will collect but they will be fined $50 for a ‘Special Collection Fee’,” says Mitchell.

Even the residents in the surrounding areas of the campus who do not want to see the mess have started to help with the educational process, enforcing fines, providing flyers and looking at other ways to help the safety of the workers. Office of Neighborhood Services also started to provide large roll-offs for the neighborhoods to try to improve living conditions during move in/move out time. “It’s an issue that’s been addressed over the years; however, since there are new students every year, it’s a challenge. We continually advertise the guidelines in the rolls of bags they receive as well as promote through social media.”

When it comes to commercial collection, customers use containers that range from 90-gallon roll-carts to 35 cubic yard compactors based on the volume they generate. Collection depends on the customer; it can be one to six times per week when service is needed. Even though there have been tough challenges, including the fact that other large hauling companies have come in and undercut the Utility’s rates which are established by ordinance, Mitchell says they work through the continuing competition focusing on excellent customer service.

aluminum bales Cardboard compactor

A Transitioning Landfill

With 720 acres of property at the landfill site, the Utility has been able to roll out different pilot projects as well as keep the extra acreage on hand for future disposal airspace. The permitted area that has been used since 1986 is 107 acres. This space has around 10 more years capacity at current acceptance levels. Two other areas on the property are rented farmland, so when it is needed, those acres will be permitted for  an additional 50 or so years. The landfill currently accepts 160,000 to 165,000 tons of waste per year. On site sits a landfill gas-to-energy (LFGTE) plant that came online in 2008 with a network of about 51 gas wells that have been added to since 1996.

“We just installed another eight gas wells in December. In addition, there were two mega watt engines in the LFGTE and a third one was brought online this fall,” says Mitchell. She explains that the energy created goes onto the grid of the city’s Water and Light Department that has owned and operated the facility for the last five years and pays the Solid Waste Utility for the gas so it’s a revenue source that was never captured before.

“We get $150,000 to $170,000 per year for the gas. There is also a green energy requirement that the city passed a few years ago requiring the city to have so much renewable energy in their portfolio each year and they are ahead of their required levels so far. The Water and Light Department says the gas collected from the landfill heats about 1,500 homes per year. Now with the third engine, it should be over 2,000.”

In 2005, the Solid Waste Utility conducted a study and determined that implementing bioreactor landfill technology could add about five years of airspace to the permitted footprint because it accelerates the decomposition of the waste, stabilizing it and generating gas more quickly in order to regain airspace more quickly. After receiving the permit in 2009, they got to work on acquiring and installing the liquid distribution system infrastructure. In the fall of 2011, they were able to begin injecting liquid into the waste while using mulch as a cover.

The cell is still in its early stages because only a portion of it was permitted as a bioreactor since it butted up against the area of the landfill that was a pre-subtitle-D landfill, which meant it only has a compacted clay liner while the bioreactor cell has a plastic liner. Says Mitchell, “The cell that we are currently filling will be our first full-size, approximately 10-acre cell that is permitted to be entirely operated as a bioreactor.

There was a lot of infrastructure involved so the earlier cell’s portion was our learning curve—installing a pumping system, wetting distribution system, different leachate collection systems, and addressing issues encountered with temperature sensors that are required by the state Department of Natural Resources, that regulates the site. We are filling a 9.28 acre bioreactor cell currently and have one more cell that is permitted to be a bioreactor that is just over 11 acres, which will be built in two to three years, so eventually we plan to be operating 2 large cells and one partial with the bioreactor operation.” She says she has already noticed a difference in the landfill.

“Gas production has gone up since we collect it from the bioreactor cells sooner. We are able to collect gas from it as you are still filling in the waste and adding liquid at the lower levels. So approximately one-fourth to one-third of our gas generation that goes to the LFGTE plant is coming from the first partial bioreactor cell.”

Compost and Mulch Operation

When the Utility began yard waste collection in 1991, an 11-acre compost facility was opened at the landfill, which was later expanded to 15 acres. At that point, curbside yard waste collection was funded by the sale of the city-logo yard waste bags. In 1992, a residential yard waste drop-off site was opened on the south side of town and in 1994, one was opened on the northwest side of town which created triangular drop off points where residents could bring leaves, grass and brush. The last two sites also allow people to load up ground mulch at no cost when available.

Yard waste has been banned from Missouri landfills since the early 1990s, so the Compost Facility is available at Columbia’s landfill site for private haulers as well as individuals who bring in pallets, brush, leaves, grass and clean drywall. Materials are ground into mulch that is either composted or used for daily or intermediate cover on the bioreactor landfill. “We are the only landfill in the state that’s allowed to put our yard waste in the landfill because of the bioreactor’s need for organic material.

By putting the mulch on the landfill for cover rather than soil, it allows for liquid infiltration and distribution, decomposes and generates gas and saves airspace. We compost some of the ground mulch with commercial food waste the utility collects. We sell compost in bulk, though there isn’t much demand for it since our area soil is good ,” says Mitchell.

Material Recovery Facility

The Utility’s material recovery facility opened in fall 2002. It was initially built to transfer recyclables; however, within the timeframe of planning and construction, they were able to obtain grant funding from the state solid waste management program and the regional solid waste management district in order to acquire a baler and sorting equipment. Within the first couple of years, the Utility was able to sort nearly everything in-house.

“We still transport a small percentage of recyclable material. Since we have a dual-stream collection and processing system, co-mingled fibers go to one side of the MRF and co-mingled containers go to another; however, if we get too much cross-contamination, we don’t have that elaborate of a screening and sorting system, so we transfer the material to a single-stream sorting facility in the St. Louis metro area.” says Mitchell.

The Utility markets the fibers quarterly, getting bids on cardboard, newsprint and paper, while plastics, aluminum and steel cans get put out for bid when there is a load available since Mitchell says  the market changes too frequently to get a monthly or quarterly bid. “We have a good relationship with a local insulation company that has been winning the bid for most of the newspaper for over a year.. In addition, there have been two companies the last couple years that have been buying our glass. We also crush, bale and market used appliances either collected curbside or brought to the landfill.”

Household Hazardous Waste Facility

Established in 1992, the household hazardous waste facility is open every year from April to November on the first and third Saturdays from 8 a.m. to 12 p.m. As an outdoor program, the Utility’s staff runs the facility. Every year, around 3,000-3,500 cars are served and people bring in materials that are banned from the landfill—paint, lawn chemicals, etc.

“We generally get a surge at the opening and the closing of the season from people who have either cleaned out their houses or are doing moving. It has been very successful; it keeps a lot of the household hazardous waste out of the landfill and the bulk of the material is recycled,” says Mitchell. Latex paint, if usable for example, is bulked into 5 gallon buckets and the following week people may pick it up for use. In addition, at the end of the season, any paint remaining is given to churches or other organizations.

The Volunteer Network

Established in 1993 with a state grant, the Solid Waste Utility’s Volunteer Network is a full-time program that consists of regular volunteers who help out with waste reduction activities. Depending on a person’s interest and knowledge base, some lead educational workshops, such as backyard composting techniques, as well as maintain adopt-a-spot locations, participate in the holiday parade, contribute to the bi-yearly newsletter (Wastelines) or work at the HHW facility greeting the public, directing the traffic, etc. There are currently 50 to 60 people who volunteer regularly throughout the year. “There is a four-hour per month requirement if you are interested in being an ongoing volunteer; otherwise, a lot of one-time volunteers pitch in for projects like big clean up events. The solid waste volunteer program was merged with the citywide Volunteer Network supervised by the Office of Neighborhood Services in October 2013 so both programs could benefit from synergies of working together,” says Mitchell.

The Utility gives tours of the landfill and MRF on a consistent basis. “Many people want to see the working MRF, especially younger groups and those who are environmentally conscious and want to recycle more. With the university here, we get a lot of environmental and engineering groups who want a tour of the landfill and recovery operations,” explains Mitchell. “We have a waste minimization program that promotes recycling, safe chemical disposal, composting, etc., so some of the volunteers make presentations and the coordinator gives presentations and may lead tours of the MRF as well. We have a waste minimization supervisor who goes into the higher-level groups as well as the elementary schools to educate students. I also give presentations to the university classes or clubs and others from time to time.”

Training and Safety

The Utility makes it a priority to focus internally on safety constantly because Mitchell knows that the waste and recycling industry is very hazardous. “Our employees are exposed to a lot of traffic, people and different situations every day with very large vehicles. We mostly get people who are fairly new holders of the commercial drivers’ license for the residential collection positions and until they have gotten more experience, there are far too often incidents.” A risk management supervisor from the Public Works Department focuses on operations, spending about 50 percent of his time with the Utility and the other half with the Transit Division. “There is also an internal solid waste safety committee made up of representatives from all of our different operations. The committee typically meets once a month to review any accidents and injuries and decide if they were preventable and what type of actions should be taken or changes we can make in our process to try to help prevent it from happening again,” stresses Mitchell.

A Share of Challenges

All the success of the many programs and operations that the Solid Waste Utility handles does not come without its problems. Not only is it continually challenging when it comes to personnel—having enough people, experience, the right credentials and experience to operate safely—but the bioreactor has also been challenging for the landfill because there have been more issues than anticipatedwith the infrastructure, the pumping system and installation. “The first set of temperature sensors that were installed with the wetting system did not work so we had about a year’s delay on being able to add the liquid due to reinstall design, approval and construction time. Within the last six months, we’ve had issues with the sewer system that handles the leachate, so we’re working on that.”

The Utility is now in the process of transitioning their 45 trucks to CNG, including roll-offs, split-hopper recycling trucks, rear-loading and front-loading commercial trucks. The first nine trucks are on order and the CNG station should be opening in Spring 2014. “The station’s operations and the use of CNG trucks are the newest things we get to adjust to,” says Mitchell. “The city has a contract with Clean Energy to build the station.

The bus system and the solid waste trucks will be the biggest fulfillers of the city’s requirements with regards to how many gallons we’ll need to purchase per month as part of that agreement. There are also big operators in town like UPS that are well known for having CNG trucks and perhaps the Postal Service will use it as well. The station will be a good addition to the nation’s CNG network because there is a station in St. Louis and one in Kansas City and we are about halfway in between those two cities.”

Looking to the Future

As Mitchell looks toward the future of the Solid Waste Utility’s programs, she says that the department is currently looking into different options for pay-as-you-throw rate structures, such as an automated roll cart collection system, manual roll cart collection or pay by the bag program. She stresses that they need to evaluate the pay as your throw opportunities and look into developing something that is supported by the community. “We need to work toward a more equitable billing system—people paying as they are using the system. For example, senior citizens are typically going to have a different amount of trash or recyclables than a big family or college student housing. Pay as you throw can fund the system fairly among all individuals who are using it, just like you typically pay for electricity and water according to how much you use.”

Mitchell is proud of the Solid Waste Utility and all that it has accomplished in the past 40 years. “We are a full-service operation, taking care of collection and disposal, whether that is at the MRF, compost facility or the landfill. Kudos to all our staff for their hard work over the years. We don’t currently have to rely on a contractor for any part of it.”

For more information, contact Cynthia Mitchell at

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