If you operate or work with a landfill in Illinois, you already know the rule: no yard waste in the municipal solid waste landfill. But the “why” behind that ban matters, especially as more sites look to grow renewable natural gas (RNG) revenue.
This blog walks through:
- Why Illinois bans yard waste from landfills
- Where that material should go instead
- How keeping yard waste out of the waste stream actually supports better biogas capture and RNG
- Where TIEROC ADC fits as an alternative wood-based input that preserves airspace and strengthens your RNG program
Why can’t we put yard waste in Illinois landfills?
Illinois does not treat yard waste as normal garbage.
State law (415 ILCS 5/22.22) banned “landscape waste” from landfills starting July 1, 1990. (Illinois General Assembly) That definition includes leaves, grass clippings, branches and other material from the care of lawns, shrubs and trees. (Illinois General Assembly)
The Illinois EPA is very clear:
- Landscape waste has been banned from landfills since July 1, 1990
- Residents and businesses are told not to put yard waste in garbage or recycling carts and not to bag it in plastic (Illinois EPA)
Why did the state take that step?
- Landfill space is limited.
Illinois banned yard waste “to address concerns about declining landfill space.” (Recycle by City) Yard waste is bulky, seasonal, and heavy. Using up airspace on material that can be composted is a poor trade for operators who need that capacity for municipal solid waste that has no other home.
- Organic waste in landfills produces methane.
Bagged organics like yard waste break down anaerobically and generate methane, a greenhouse gas far more potent than CO₂ over a 20-year period. WBEZ By diverting yard waste to composting, the state reduces uncontrolled methane potential in the landfill.
So the short answer to “why can’t we put yard waste in landfills?” is:
Because it wastes airspace and adds methane load that could be managed more efficiently outside the landfill.
Where should yard waste go instead?
Illinois did not simply ban yard waste and walk away. The ban helped seed a statewide organics infrastructure.
The Illinois EPA and regional agencies recommend several options: (Illinois EPA)
- Grasscycling – leave grass clippings on the lawn as a nutrient source
- Mulching – use chipped branches, leaves and clippings as mulch around trees and beds
- Permitted compost facilities – send yard waste to dedicated compost sites
- Municipal or hauler collection programs – seasonal curbside programs and drop-off sites
- On-site composting – household or small on-site piles, especially for urban farms and gardens
Advocates note that “landscape waste was banned from landfills in Illinois in 1990” and that this has helped grow a network of landscape waste composting facilities and jobs across the state. (Illinois Environmental Council)
From the state’s perspective, that is a win: yard waste becomes a soil amendment, not a permanent occupant of limited landfill airspace.
Inside the landfill, organics should work harder
Even with the yard waste ban, Illinois landfills still receive a large stream of organic material:
- Food waste
- Paper and cardboard
- Wood, textiles and other biodegradable fractions
- Certain forms of alternative daily cover (ADC) that are organic in nature
Those organics are the primary feedstock for landfill gas.
At the same time, landfills are becoming energy assets:
- As of August 2025, there are about 589 landfill biogas facilities operating in the U.S., an 18–19 percent increase since 2020. (American Biogas Council+3American Biogas Council+3Waste Today)
- Since 2020, the share of landfill gas upgraded to RNG has grown from 19% to 40%, according to the American Biogas Council.
In DeKalb, Illinois, for example, WM recently opened a $60 million renewable natural gas (RNG) facility that is expected to generate about 1 million MMBtu of RNG per year, enough to supply roughly 11,500 households annually or fuel up to 865 heavy-duty vehicles per day by capturing landfill gas that would otherwise be flared. (American Biogas Council)
In other words, every ton of organic material you do bury needs to pull its weight:
- Generate predictable biogas
- Flow cleanly into your gas collection system
- Support a high-BTU, low-contaminant feed for RNG
Daily cover: where airspace really gets used up
On top of the waste itself, operators spend a lot of airspace on cover.
Illinois regulations require that by the end of each operating day, all exposed waste must be covered with at least six inches of clean soil, unless an alternative daily cover is approved that performs as well or better in controlling litter, vectors, fires and odors. (Illinois Pollution Control Board)
Using soil or rock as the default daily cover:
- Consumes valuable airspace every single day
- Adds weight and material that does not contribute to biogas generation
- Can complicate wet-weather operations and create muddy working faces
Other states, like Wisconsin, have long recognized this and explicitly encourage the use of ADC materials (spray-on slurries, foams, tarps, industrial byproducts) that meet performance standards without sacrificing capacity. Illinois allows similar ADC approaches under its “equivalent performance” language for daily cover.
For an Illinois landfill that cannot accept yard waste, daily cover is one of the biggest levers you still control if you want to:
- Preserve airspace
- Improve working conditions
- Support a stronger, more predictable gas collection system
TIEROC ADC: recycled wood fiber that supports RNG
This is where TIEROC comes in.
TIEROC ADC is engineered from clean, recycled wood – primarily recovered railroad ties that are processed into a clean wood fiber product. Unlike soil or rock, TIEROC is:
- An approved Alternative Daily Cover (ADC) material that meets regulatory performance requirements
- A biomass fuel supplement with quantifiably high BTU value, comparable to many coal sources and higher than typical woody biomass
- A secondary producer of biogas once it is landfilled and incorporated into the waste mass, contributing to landfill gas generation instead of just taking up space
Key advantages for Illinois landfills and RNG partners:
- More coverage, less weight – TIEROC’s low density means operators get more coverage per ton than soil. That preserves airspace and stretches permitted capacity.
Better gas profile – As an organic, high-BTU material, TIEROC contributes to methane generation instead of diluting it with inert cover.
- Cleaner emissions for energy users – Testing shows TIEROC can reduce NOx, SOx, VOCs, chlorine and mercury compared with many coals when used as a fuel supplement downstream.
- Weather-resistant application – It applies cleanly in wet, cold and shoulder seasons when soil is difficult to work with, supporting consistent daily cover compliance.
For RNG developers and landfill gas partners, that matters. The American Biogas Council reports that 77 of the 92 landfill biogas facilities opened since 2020 upgrade their gas to RNG, a shift that has nearly doubled RNG’s share of landfill output. (American Biogas Council) As more projects prioritize high-quality gas, the characteristics of your waste stream and cover materials become part of your energy strategy.
Connecting the dots: yard waste ban + ADC + RNG
Let’s put it all together from an Illinois operator’s perspective:
- You cannot landfill yard waste. State law and local ordinances direct that material into composting and mulching streams to conserve space and cut uncontrolled methane emissions. Illinois Environmental Council+3Illinois EPA+3Illinois EPA+3
- You must still cover the working face daily, traditionally with six inches of soil, which consumes capacity and contributes nothing to gas output. Illinois Pollution Control Board+1
- You want biogas to work harder for you, because RNG investment and demand are rising, with more than $1 billion per year flowing into landfill biogas projects and RNG’s share of landfill gas output growing from 19% to 40% since 2020.
TIEROC ADC gives you another option:
- Yard waste stays out of the landfill, as required.
- Your daily cover becomes a productive organic input, not a dead load.
- You preserve airspace, maintain compliance, and support stronger, more predictable biogas generation that can be upgraded to RNG.
Instead of seeing the yard waste ban as a constraint, Illinois landfills can treat it as a signal to rethink what occupies scarce airspace, and to prioritize materials and practices that convert that airspace into long-term revenue, not just short-term cover.
Ready to explore TIEROC ADC at your Illinois landfill?
TIEROC is already being adopted by landfills across the Midwest that want to:
- Replace soil or rock as daily cover
- Preserve capacity and improve operating conditions
- Strengthen their landfill gas profile and RNG partnerships
If you would like to evaluate TIEROC ADC at your site, TIEROC can help you:
- Model airspace savings and potential gas yield impacts
- Align with Illinois daily cover requirements and permit conditions
- Coordinate with RNG developers and off-takers to maximize fuel value
Interested in modeling airspace savings and gas yield impacts? Connect with Greg and the TIEROC team at (847) 426-6354, or greg.kutschke@tienergy-usa.com.
