IOWA CITY, Iowa (AP) - Jennifer Jordan walks up to a 250-foot mound of compost on a sunny morning at the Iowa City Landfill and Recycling Center.
She spears it with a thermometer and smiles as the gauge soars to 160 degrees Fahrenheit, almost 70 notches above the outdoor temperature.
"Is that not so cool?" marvels Jordan, the city's resource management superintendent. "That's the process. That's Mother Nature."
The pile is made up of food scraps, like eggshells and banana peels, and yard waste, like dead wood and mown grass. But it doesn't stink. Even in the winter, the sped-up process of natural decomposition generates enough heat to convert what was once Johnson County residents' leftovers into rich soil.
But the city is running out of space to turn the 11,500 tons of yard and food waste it collects every year into soil. It's among two large-scale composting sites in Iowa that accept food, even though food scraps makes up 20% of the state's waste stream.
That means Iowans send an estimated 556,313 tons of compostable food to landfills each year, according to the most recent estimates. It not only takes up space and stinks up the air, but also generates methane, a greenhouse gas.
But even if more Iowans decided to sort their food waste, the state's current composting infrastructure wouldn't be capable of processing it.
The Iowa City Press-Citizen reports that just six facilities are permitted by the state to accept more than two tons of compost per week, and two of them accept food scraps. Another 77 sites process compost - not necessarily including food - but can't cross the two-ton weekly threshold.
None of this is news to Jennifer Trent, program manager at the Iowa Waste Reduction Center. She's also the vice president of the U.S. Composting Council.
"When I started looking at ways to divert food from the landfill through composting (in Iowa), I noticed a huge deficit. But it seemed so easy to me for a municipality to start something," she said. "And I found out, it's definitely not the low-hanging fruit, it's clear up at the top of the tree, and it's a problem that we have to solve."
Iowa passed a law preventing yard waste from ending up in landfills in 1991 and, as a result, kickstarted a checkerboard of yard waste composting programs.
Only eight states have implemented laws to prevent food waste from ending up in landfills, according to the U.S. Composting Council.
Trent said, when she began targeting food waste reduction with the IWR about 10 years ago, she found the average person didn't know about food waste composting and its implications for the climate.
That has now changed, she said, although there's work to be done.
"People are learning about it, people are hearing about it, and I think it's just taken an educational awareness to make a difference," she said.
Staff at Iowa City's compost site take the piles' temperatures twice a week to ensure they're hot enough for microorganisms to break down the material and kill disease pathogens.
If the temperature reaches 185 degrees Fahrenheit, they spread out the waste to cool down; when it's too hot and dry, it can start on fire. They also have to check oxygen levels monthly and "turn" the piles - essentially stirring them so they cook evenly like dinner in the crockpot.
The mounds range from light to dark brown depending on their stage in the process. It's a powerful demonstration of nature. Jordan remembers a call from the nearby city of Coralville hoping to dispose of a truckload of dead fish. They once received a tanker load of rotten eggs.
In both cases, they were composted successfully.
The process as a whole takes about a year. At the end, the fertile soil is checked for safe levels of ammonia and carbon dioxide. It's sold for $20 a ton - one cent per pound. On average, the center sells 2,600 tons a year.
Theresa Stiner, a senior environmental specialist with the Iowa Department of Natural Resources, said the agency wants to encourage composting, but at the same time "protect the environment where it's happening."
Runoff from poorly managed compost facilities can endanger the environment; soil that results from the process must be safe for use.
A large composting facility in Eddyville closed last summer after violating several permit regulations, including by allowing runoff to get into the ground. Locals complained of being unable to open their windows or spend time outdoors due to the smell, according to local news coverage.
Trent, with the IWR, said the facility "smelled to high heaven" and as a result, damaged the reputation of composting in the area.
"I started getting phone calls all the time from companies and businesses looking for somewhere to send their food waste, and I just had to tell them, there's nowhere. It's all being landfilled again," she said.
Trent would like to see the two-ton composting limit increased so it's easier to open and grow composting businesses - still with the environmental protections written in. As it stands, the process of getting a permit to go above that threshold is expensive and cumbersome, she said.
Plans are in the works to review the state regulations, Stiner said.
The DNR has received a number of requests for variances to the current regulations, Stiner said, which is a signal it could be time for an update. That means someone asks to bypass a regulation, assuming they can prove they won't harm the environment in the process.
"(The regulations) just need to be brought up to speed with what other states are doing and the current state of composting is," she said.
Other states allow for more curbside programs and industrial-scale composting facilities, whereas Iowa City's program is rare for the state.
The first half of the process means spending months working internally to draft the updated regulations, she said.
Then, a formal nine-month process begins. That includes getting approval from the Iowa Environmental Protection Commission, a nine-person board appointed by the governor. The updates would also be presented to the Administrative Rules Review Committee within the Iowa Legislature.
Kaveh Mostafavi is CEO of the Compost Ninja, a private company in Iowa. He looked into getting a permit for a large-scale compost facility but decided it was too expensive.
The company collects food scraps for composting in Des Moines, but without a local option to bring them to, drives the waste back to Iowa City. He said he hopes to invest in electric vehicles to reduce the environmental impact.
"We're super lucky that we have the Iowa City landfill that takes the food scraps," he said. "They have the most nutritious, amazing compost at the end. But at the end of the day, the infrastructure doesn't exist to do this on a massive scale."
The Iowa City composting site got a permit to go beyond two tons weekly in the late 2000s. It came about after a group of University of Iowa students pushed for a food scrap compost program and worked with the city and university to test how it might work.
As a result, the city launched a "curbside" program in 2017 to make it easier for the average resident to compost food waste. People living in single-family homes to four-plex apartments can request a 25- or 95-gallon compost bin to accompany their recycling and trash pickup for an extra $2 monthly.
About half of the city's households participate, Jordan said.
In addition, the $45 to $50 per-ton fee to "tip" garbage into the landfill goes toward the composting program. In other words, as the compost program continues to grow, it loses money.
The city is in the midst of figuring out how to expand its space for composting, knowing it is already running out.
And that there's more to be collected.