Both the CacaLoco composting operation and city of Rifle wastewater treatment plant are being looked at as potential odor sources that have caused some West Rifle residents to keep their windows closed and stay inside some days.
Businesses complained last month to Rifle City Council about customers staying away due to the odors. The composting operation is overseen by Jim Duke, who has had similar operations between Carbondale and Glenwood Springs for more than two decades.
City council approved a contract with Tetra Tech on May 2 to try to find some solutions for both the plant and composting. The company previously oversaw an energy audit of city facilities and operations.
"The residents in West Rifle expect the odor issues to be addressed, and while the complaints were directed towards the composting operation, it seems prudent for the city to address all potential odor sources," wrote Assistant City Manager Matt Sturgeon in a recommendation letter to the council.
"We really need to know exactly what it is we're dealing with out there and if we can mitigate it," he said at the meeting.
City council awarded a contract to Term Tech in the lump sum amount of $22,510. Funds from the city wastewater fund will pay for the project.
The treatment plant is included to determine the severity of the odors it may produce, compared to the composting facility, and to see if they can be mitigated through changes in operational procedures. The composting facility is anticipated to be the primary odor source, according to written material from Tetra Tech to the city.
Bob Lonergan, senior process engineer for Tetra Tech, is the project manager. Lonergan said if done correctly, composting is a "very green way to deal with the solid wastes you get from wastewater treatment."
Lonergan said samples were taken at the Rifle site on May 3, from both the treatment plant and composting facility.
"We want to make sure the odors are not coming from the plant," since it is the city's responsibility, he added.
Each sample was sent to ALS-Kelso, previously Columbia Analytical Services, Inc., for analysis.
A city certificate of designation defines the operation of the 10-acre site. It can accept up to 11,000 cubic yards of biosolids from the city's nearby plant, septage, animal bedding and manure and portable toilet wastes. Other acceptable materials are wood and yard wastes, paper, cardboard and food wastes. The materials are mixed in specific piles on the site, with heavy equipment used to aerate the material and help the composting process.
The Colorado Department of Public Health and Environment found several concerns with Duke's operation during a compliance assistance inspection on April 11. Some had to do with paperwork, but inspectors noted odor complaints were not adequately addressed within seven days, as the certificate requires. Other concerns focused on stormwater drainage and pad liner permeability to protect groundwater sources. Duke has expressed strong remorse for the odor problems.
Lonergan said he spoke with Duke about his operation and said the operator is complying with federal regulations regarding the control of pathogens associate with composting.
"We want to see if there's a way we can further reduce the odors," Lonergan said. "The samples will look for about 20 compounds that produce odors."
The goal is to find long term solutions, he added, and pointed out that Duke has ended accepting food and grease waste at the composting site, two common odor sources. Duke has also installed low pressure misters around the entire fence line of the site. The misters spray an organic solution used by hospitals to help reduce odors, he said. Atomizer fans were also placed within the site and misters sit on top of the compost piles as well.
"It's in everyone's best interests to minimize the odors, so the city can continue to save some money" by turning its solid waste over to the adjacent composting facility, Lonergan added.
He expected to have the sample results by May 18, then submit a final report to the city in three or four weeks.
"There's no absolute guarantee there will never be odors coming from the plant or the composting," Lonergan said. "But we can take steps to minimize them."