Finishing the job

Boulder County residents help spur investigation that could close CEMEX plant near Lyons


They call it “the worm.” It’s the enclosed conveyor belt suspended above Highway 66 outside of Lyons that used to bring raw materials from the Dowe Flats Quarry to the adjacent CEMEX Lyons Cement Plant across the highway. 

Dowe Flats’ mining permit expired on Sept. 30, but the sand-colored tube still hangs overhead — a clear reminder for some Lyons residents of an incomplete campaign, including Amanda Dumenigo, executive director of Save Our Saint Vrain Valley.

“Here it is looming over the highway. We think it’s going to really be very inspiring to the community to have that be gone,” she says. 

Dumenigo is part of another wave of activism against CEMEX — this time targeting the plant itself — that helped spur the Boulder County Planning and Permitting Department (CPP) to investigate the plant’s nonconforming use status.

If the County finds violations, steps could be taken to shut down the plant.  

The Lyons CEMEX Plant was built in 1969 and acquired by CEMEX in 2000. In a July 2022 letter to the Lyons Recorder, a CEMEX representaitive wrote that the company “has a lengthy history of actively seeking mutually beneficial relationships with its neighbors, nonprofits and local businesses, as well as investing in area stakeholders.”

Local residents have raised concerns about the plant for decades, citing its negative impacts on things like air quality, light and noise pollution. 

On Sept. 29, the Boulder County Commissioners denied CEMEX’s permit application to keep mining at Dowe Flats. Although environmental activists touted this ruling as a community-wide win, there was still uncertainty as to whether or not CEMEX could operate without the adjacent mine.  

At the time of Dowe Flats’ closure, Boulder County Parks & Open Space wrote that CEMEX could operate its plant “indefinitely even after the mine closes.” 

In part, this is because of the plant’s 1994 legal nonconforming status, which means it was built before current zoning laws. As long as CEMEX doesn’t increase the size of the plant or its footprint, it can continue operating. 

However, some community members argue that without the mine next door, CEMEX has already violated its nonconforming use status, namely by having to truck in materials. 

Mayors, city counselors and boards of trustees throughout Boulder County signed a Feb. 14 letter drafted by Lyons-based environmental advocacy group Good Neighbors of Lyons urging the County to review and terminate the company’s nonconforming use status.

The letter claims “new intensive uses [at the CEMEX Plant] clearly trigger the nonconforming use termination clause,” citing anecdotal evidence of increased truck traffic and new stockpiling of shale and other materials. 

Lyons Mayor Hollie Rogin, who signed onto the letter to the commissioners, also claims “there’s a huge increase in dust.” 

Dumenigo is confident there are substantial changes at the plant. 

“It’s undeniable,” she says. “And [the commissioners] have the judicial duty to review the nonconforming uses and potentially revoke them.”

CPP wrote a letter of disclosure request to CEMEX for documentation showing the amount of truck traffic on and off the site, the amount and type of material transported, and the type of material stockpiled at the site — both historically and after Dowe Flats closed. The conveyor system on the cement plant site is also under review. 

The original deadline for CEMEX’s response to CPP was Feb. 27, but the company received an extension until March 27. 

Because it is an ongoing investigation, the County wasn’t willing to provide further comments. 

Dale Case, director of CPP, told Boulder Weekly last fall that the mining permit at Dowe Flats expiring doesn’t change any permitting for the cement plant, but it’s possible CEMEX could take steps that would trigger a loss of its nonconforming status. 

If the County finds no violations, the plant will operate per usual. If it determines the nonconforming use “has been or may have been terminated,” CPP Director Case will send a notice to CEMEX, which will then have 30 days to provide evidence of showing the determination is in error, to correct modifications, to apply for approval of a special use permit, or to appeal the determination to the Boulder County Commissioners.