“We always want to be ahead,” Riley said.

The main reason the upgrades are planned is the age of the plant, which was originally built in 1968. Earlier this year, a consultant presented to Ketchum leaders an analysis of the facility that concluded it needs some $37 million in upgrades between this year and 2042. Some components of the plant are more than 50 years old and somewhat degraded, the consultant noted.

The costs would be split evenly between Ketchum and the Sun Valley Water and Sewer District. Ketchum’s plan for funding its share of the costs calls for selling municipal revenue bonds to buyers and combining the proceeds with monthly income from sewer fees paid by homeowners and businesses. The fees would be bolstered by a 7% rate hike in fiscal year 2023, followed by 5% rate increases in subsequent years, subject to annual review.

The proposed ballot language for the bond question notes that if the city pursued a “non-debt” funding plan paid for only with income from sewer fees, it would have to raise the fees by 60% in fiscal year 2023 and 25% in the following two fiscal years. That approach would not only dramatically raise ratepayers’ out-of-pocket costs, Riley has said, but would place much of that cost burden on existing ratepayers, instead of spreading it out over the duration of the proposed bonds.

Currently, the monthly sewer fee for a single-family home in Ketchum is $41.85.

Revenue bonds are commonly used to generate income to fund major municipal projects. Though they are a form of debt, unlike general-obligation bonds, they are not paid for with the municipality’s tax income. Revenue from the facility at issue—in this case, sewer fees paid to the city—are used to make interest and principal payments to the purchasers of the bonds.

Approval of and issuance of the bonds would not affect residents’ property taxes.

Issuing up to $14 million in revenue bonds would require paying market-rate interest to the buyers. Based on a market interest rate of 3.77% for 20-year bonds, the city estimates it would pay about $7.25 million in interest in addition to the principal amount of $14 million.

The Sun Valley Water and Sewer District is working on its own funding plan to pay for its share of about $18 million—the sum it would owe if all of the improvements are made.

To proceed with the bond issue, Ketchum will need to garner 50% approval from voters, a lower threshold than the taxpayer-backed general-obligation bonds.

City: Plant works, but needs to be better

The wastewater plant is functioning well, Mummert said Wednesday, but the old age of the facility is starting to show.

On a daily basis, some million gallons of sewage—sometimes 1.25 million or 1.35 million gallons during busy periods—flows into the site, where it is first pushed through a 5-millimeter screen to remove larger solids. The wastewater is then pumped into a facility to “settle” and further separate solids, before it is pumped to large basins, where a “sludge” full of microorganisms—or “bug stew,” as Mummert calls it—is added.

Comparing the process to a Thanksgiving feast, Mummert described how the microorganisms then eat away at the sewage.

“Basically, we’re bug farmers,” Mummert said. “The microorganisms are what treat the wastewater.”

After that process, the liquid is sent through a “clarifier” to further remove tiny solids, and eventually through a disinfection process that uses ultra-violet light to kill any remaining pathogens. Chlorine could be used for disinfection of the end-product, Mummert said, but then has to be removed.

In the end, clear water is released.

“It’s as clean as can be,” Mummert said.

The seven workers at the plant “shoot for perfection,” not the cleanliness targets of the permit, Mummert said, noting that the water produced at the end stage is significantly cleaner than it is required to be. To prove their point, the plant’s staff uses the finished water to maintain an aquarium with fish at the end of the line.

In the warmer months of the year, much of the water produced from the treatment process is labeled as “reuse water” and pumped to the nearby Weyyakin subdivision and Elkhorn golf course for irrigation. Water that is not reused for irrigation is released into a branch of the Big Wood River.

The solids captured in the process are trucked to the Ohio Gulch dump facility, where the sludge is dried into powder in open-air lagoons. The city is researching how it could turn most of the by-product solids into compost, Riley said.

Though the plant is discharging clean water, the upgrades are necessary, Mummert said. Two aeration basins—where the microorganisms treat the wastewater—are 54 years old, he noted. In addition, the plant uses a 38-year-old “aerobic digester tank” and its clarifier is also 38 years old.

Improvements will also allow the plant to comply with anticipated tighter limits on the discharge of ammonia into the river, city officials have stated. In addition, though the plant does not operate near its capacity, long-range planning calls for expanding capacity to accommodate some future growth, they have said.

The issuance of the full $14 million in bonds would be a “worst-case scenario,” Riley said, noting that they will be sold as needed, with most of the projects at the plant happening in the next 10 years.

For additional information on the proposed bond issue, go to projectketchum.org.