After a pattern of permit violations dating back over a decade, Durango-La Plata Airport will receive a new wastewater treatment system next year. The Colorado Department of Public Health and Environment has issued compliance advisories to the airport periodically since 2010, citing both missed discharge monitoring reports as well as reports that contain data indicating that the discharged effluent exceeded certain limits set by the state.

The airport’s current system is composed of a series of three lined wastewater lagoons. Wastewater is treated using calcium hypochlorite – effectively chlorine – and chlorination tablets. Two of the lagoons are aerated to promote the activity of the bacteria that break down wastewater while the third is not, allowing solids to settle before the effluent is discharged into the Florida River.

Toni Vicari, the airport’s aviation director, said the specific technology for the new system has yet to be determined. However, he said the lagoon system would remain, aided by some sort of new technology to assist the airport in meeting the limits established in its permit.

“There are a number of proprietary technologies that exist out there to be able to take a traditional lagoon system and add a degree of additional technology to the lagoons to be able to … meet those increasingly stringent state guidelines,” he said.

The airport is not alone in its predicament. Noncompliance has become a common problem for older wastewater systems as CDPHE has tightened the standards for wastewater effluent in recent years. Lagoon systems are particularly susceptible to exceedances in ammonia limits because the bacteria that break down the organic aterial become dormant in cold weather.

SEH, a national engineering firm with an office in Durango, has helped the airport through the pre-design process. Vicari said the airport will send out a request for proposals by the first week of January and will select a technology based on the responses. He hopes to have construction underway by the second or third quarter of 2023.

The city of Durango has $900,000 listed in the airport enterprise fund for the project, $150,000 of which has already been spent. Although it is a department of the city, the airport operates financially independently of the city’s budget.

“The challenge we face typically is that (the water and wastewater systems), unlike a major central water or wastewater utility, don't have a big user base associated with them. And so consequently, the financial aspect can be difficult for us,” Vicari said. “The amount of revenue that we drive from utility billing is very small comparative to significant central water wastewater system. And so we run these systems at significant losses financially, and basically they're subsidized by the revenues that we generate through aeronautical revenue at the airport.”

The recent compliance advisories issued by CDPHE have stemmed from violations of the schedule established by CDPHE. The most recent permit, issued in 2018, lays out a series of dates by which the airport must have completed certain steps in the process of implementing a new treatment system. The airport has lagged in completing those steps because of financial restrictions, Vicari said. CDPHE has not issued any fines.

“We initially began scoping that project and pretty early on realized that the financial impacts of the project were going to be significantly more substantial than what we originally anticipated,” he said. “… The principle delay was just that – it was making sure that the airport finances are in line to be able to execute the project once we got our arms around what the realistic scope and cost were going to be.”

The upgrades to the system are intended to comply not only with CDPHE’s standards, but are also built to handle any increase in the volume of traffic through the airport that might take place as a result of the expansion to the terminal, which is also anticipated to begin this spring.

“We, like anybody, want to make sure that we’re discharging water into the environment that is healthy for all because … we’re pulling water out of the Florida for the drinking side and ultimately treating it as well,” Vicari said. “So we have a huge stake in terms of the environmental quality of the surrounding waterways around the airport, and we’re committed to doing that right.”

rschafir@durangoherald.com