Drying biosolids in summer pays off for Cashmere

CASHMERE — It is nobody’s favorite topic at the dinner table, but the way Cashmere handles what goes down the drain is saving the city tens of thousands of dollars a year.

At the Nov. 25 City Council meeting — with Mayor Jim Fletcher presiding and councilmembers Jeff Johnson, Chris Carlson, John Perry, and Jayne Stephenson (via Zoom) in attendance; Councilmember Shela Pistoresi excused — staff reported that the city’s new hybrid approach to managing wastewater “biosolids” cut hauling costs by an estimated $50,000 this year. Director of Operations Steve Croci, Treasurer/City Clerk Kay Jones, and Wastewater Services Manager Dorien McElroy were also present.

The council unanimously approved a four-year extension with Boulder Park, the regional contractor that hauls and land-applies the city’s biosolids. Boulder Park still handles Cashmere’s material year-round, but summer hauling has dropped dramatically thanks to an expanded use of drying beds at the wastewater treatment plant.

“It was a net savings for the year of about $50,000 by doing the drying since the beginning of May,” staff told the council, noting the figure already accounts for operator time spent on drying operations.

Why costs rose even as hauling decreased

The contract extension includes a roughly 5 percent increase on one hauling rate and about 14 percent on the winter-heavy rate. Johnson and Perry both asked why costs were rising at all if the city was hauling less.

Croci explained that Boulder Park’s fixed costs remain the same even when summer hauling slows. “He’s obligated these trailers for this work,” Croci said. “Even if we’re just having one during the summer months, those trailers are sitting there — he still has to pay insurance, he still has to pay registrations. And in the winter, there’s a possibility the sludge can freeze in the trucking container and he has to bring it inside a heated bay.”

In earlier years, Boulder Park kept two trailers in constant rotation — one filling in Cashmere while another was already on the road. With drying now taking over from May through mid-October, that rotation changes, and the contractor adjusted rates to reflect the shift.

Jones reminded the council that drying does not eliminate the need for hauling altogether. “It’s still our biosolids,” she said. “Whether it’s wet or dry, it has to get hauled.”

Finding the “sweet spot” in the trailer

When winter hauling resumes, moisture levels become highly variable — and that affects how full a trailer can safely be. Loads that appear full can settle overnight, while wetter batches may reach weight limits unexpectedly.

Speaking via Zoom, Wastewater Services Manager Dorien McElroy said staff are tracking every winter load closely.

“As soon as the trucking operation gets it to the scales, he sends me the weight,” McElroy said. “We’re marking a line inside the truck — this is how full it should be — and we’ll keep honing that in.”

She added that drying creates savings, but the city still has to manage how long dried material sits. “When we cut into that November stock in August, it stinks terribly,” she said. “So we’re looking for ways to optimize that.”

What drying looks like — and why the council talked about doing more

Drying biosolids is simple in principle. Operators spread material in open beds during warm months, letting sun and wind remove moisture until the remaining solids shrink and weigh less. Boulder Park still hauls the dried material — just at a far lower frequency than before.

Councilmembers asked whether the city could extend that window beyond May through mid-October. Croci said that’s worth exploring if savings continue.

“If we can get our cost down,” he said, “we should be looking at other ways to maybe optimize that. Maybe a cover over the drying area, maybe some other infrastructure.”

Stephenson participated via Zoom and signaled support for the staff recommendation, though she did not comment verbally.

A quiet part of Cashmere’s infrastructure story

Most residents will never see the drying beds tucked behind the wastewater plant, nor the hours operators spend balancing moisture content, tracking load weights, or calibrating winter hauls. But for a small city looking to stretch every ratepayer dollar, councilmembers said the early results of this hybrid approach are encouraging.

Mayor Fletcher noted that steady, incremental efficiencies like this are exactly the kind of operational improvements the city needs to keep finding. The biosolids contract may not be glamorous, and the savings won’t appear directly on utility bills, but the behind-the-scenes shift is already helping Cashmere reduce costs without cutting service — a small but meaningful win in a year filled with hard infrastructure choices.

Andrew Simpson: 509-433-7626 or andrew@ward.media