Custer County officials consider pilot wastewater treatment, biosolids application as PFAS tests and funding worries mount

Round Mountain sanitation officials told the Custer County Board of Commissioners on an evening public forum that they have 180 days to stand up a pilot wastewater-treatment system intended to treat effluent and remove roughly 1.2 million gallons of decades-old sludge from town lagoons, then dispose of or apply the resulting biosolids.

The pilot, Round Mountain General Manager Dave Snyder said, is a lower-cost alternative to a previously proposed $14 million mechanical plant the district could not afford. Snyder said the pilot’s price is about $1.6 million, and that the district has assembled roughly 88% of funding through a donated treatment trailer and allied grants and private contributions; the district’s match is about $300,000. Snyder said Denali Water Solutions and other vendors have provided donated equipment and engineering support and that the county has been asked to help locate a suitable land-application site.

The proposal has immediate community scrutiny because samples for “forever chemicals” (PFAS) produced conflicting numbers and because the project would move material from long-accumulated lagoons. Residents and the Custer County Conservation District urged caution and stronger public review, arguing the selected Johnson Ranch site described in planning documents is dry, sloped and close to creeks and domestic wells.

Why it matters: the pilot is intended to give a path for Round Mountain to meet state and federal discharge requirements without building an unaffordable mechanical plant. County and district officials said the pilot could also test a combined approach—microalgae, fine-bubble aeration and an electrocoagulation/electrochemical (EC) unit—that they say can reduce nutrients, metals and some PFAS. Opponents said uncertainty about PFAS in the actual solids and the proximity of the proposed application site to water supplies merit more study and regulatory scrutiny.

Snyder described the technical and financial background: the district has operated lagoon treatment since the 1970s, and state-imposed discharge limits and soil constraints forced multiple redesigns. “We were put on a compliance schedule to replace that wastewater treatment plant,” Snyder said, recounting an earlier process that produced a design with an estimated cost above $14 million and roughly $700,000 in engineering expenditures to date. He said the new pilot pairs microalgae and a small electric-coagulation unit that “can destroy the chemical bond of the PFAS” in bench tests and in larger demonstrations elsewhere, and that a donated trailer system valued at about $800,000 substantially reduced capital needs.

Denali Water Solutions’ environmental director, Luke Vaughn, told the meeting that “we would not be able to do any of the application with this sludge if it was untreated sewage. But as Dave just explained, lagoons do a really good job at treating. So this is treated material.” Vaughn described tests run by the district and by Denali’s partners showing strong removal of bacteria and many metals and partial removal of nutrients; he said EC units remove solids and can reduce concentrations of some persistent chemicals when integrated with a tailored front-end treatment.

Residents pressed for specifics. Citizen Matt Hiles read a lab excerpt alleging a PFAS result of 61 parts per billion in one sample; Vaughn and district staff said that earlier liquid-sample results and later data were inconsistent, that a different analysis showed much lower PFAS (Denali cited 3 parts per billion for a later liquid sample), and that a solid-sample run using a different collection method was still pending. The district said the initial liquid sampling had been shared late with staff and that the “solid” (sludge) test requested by the state had not yet been returned to the county. Snyder acknowledged the confusion, saying the state had required an additional, longer-running pilot study and that the district had 180 days from the recent state approval to get the pilot running.

Multiple residents, and a written letter from Robert Miller, president of the Custer County Conservation District, urged a moratorium on spreading biosolids on the Johnson property. “The selected site is a dry site…A crop is established and therefore would be highly inadvisable to excise any disturbance of the soil,” Miller wrote, and asked the county to halt the site plan. Miller and other speakers pointed to wind, dust, proximity to Macy Creek and the Arkansas River tributary network, and to uncertainty about how PFAS behaves when sludge that has accumulated for decades is disturbed.

District and Denali presenters said they are looking at alternatives, including dewatering and transporting dried solids to a municipal landfill or installing a belt press to produce cakeable solids for landfill disposal; both paths would add cost. Snyder acknowledged hauling or additional dewatering could be more expensive than the proposed land application at the Johnson site, but said the pilot’s donated equipment and several grants had brought the district close to its funding goal: “We got about 88% funded before we had to put our first money into this so we’re really excited.”

Regulatory context: speakers repeatedly referenced federal and state biosolids rules. Denali and district staff cited the Clean Water Act biosolids rules commonly known as 40 CFR 503 and Colorado Department of Public Health and Environment (CDPHE) permitting and discharge limits. County legal staff reminded the public that the state agency is the primary permitting authority for biosolids applications and that county land-use and zoning review will be separate from, and can run in parallel with, state permitting.

What remains unresolved: (1) the PFAS testing record—residents noted a reported 61 ppb result on one liquid test while Denali and district staff pointed to a different, lower reading and to a pending solid-sample analysis; (2) a final decision about the Johnson Ranch as the application site versus hauling to a landfill or another property; (3) whether the pilot treatment system as configured will meet CDPHE discharge and solids-quality requirements in winter conditions; and (4) how costs beyond the current $300,000 district match would be covered if hauling or additional dewatering is required.

County next steps include a planning-and-zoning review of biosolids rules and continued public outreach; district staff said they will seek to have the pilot online within the 180-day state window and will share solid-sample results and the pilot design for further public review. The state remains the principal regulator for permit decisions under the Clean Water Act and Colorado law.