Pueblo wastewater projects projected costs = $56.7 million over 10 years

Photo of lined pipe via Insituform France.
Photo of lined pipe via Insituform France.

From The Pueblo Chieftain (Chris Woodka):

In the next 10 years, Pueblo will have $56.7 million additional costs to treat wastewater, according to information presented in a recent City Council work session.

More than half of that will occur because of a $31.5 million program to line pipes to keep groundwater out of the sewer system. The option is less expensive than trying to remove selenium at the wastewater treatment plant.

The other $25.2 million is for increased chemical and electricity costs to remove nutrients.
More costs could arise as regulations continue to change.

In December, council approved rate increases of about $3 per month to begin covering the costs. For a home billed for 4,000 gallons of sewage monthly, the total amount is $28.67.

By 2020, the rate will increase to $43.49 per month, with $7.60 of that attributable to the selenium program. The city is spending $1 million to line pipes this year, $2 million next year and $3.5 million each year thereafter to complete the process in 10 years.

The Colorado Water Quality Control Commission in December extended a temporary modification for Pueblo, but said a discharger specific variance is needed by June 2018. At that time, Pueblo will have to present its plan for complying with a numeric limit for selenium discharges from its wastewater plant.

More coverage from Chris Woodka writing for The Pueblo Chieftain:

Pueblo couldn’t kick its selenium habit no matter how hard it tried.

Selenium, a natural occurring element that can be toxic at high levels, is loaded into surface water and groundwater as it comes into contact with Pierre shale formations on Wild Horse Creek and Fountain Creek.

But Pueblo’s sewage treatment plant is under the gun to meet state standards within two years, before it is able to prove its point that water leaving the plant actually reduces the selenium that enters the Arkansas River.

What’s more disturbing is that a $31.5 million experimental program to reduce selenium in wastewater lines might actually increase the amount that reaches the river.

The issue has become a matter of contention between Councilman Chris Nicoll and Commissioner Terry Hart, who face off for Hart’s seat in the June 28 Democratic primary. Nicoll says Hart led legal opposition to the city’s case before the state Water Quality Control Commission. Hart says the county pulled out before the state’s eventual decision.

The city was trying for a 10-year path toward a solution, but was given just two years to come up with a plan.

“The wastewater plant is responsible for 6 percent of the selenium loading into the river,” said Pueblo Wastewater Director Nancy Keller. “We could take out 100 percent, and have no impact.”
In many cases, selenium could wind up in wastewater because of industrial processes. In Pueblo, it occurs naturally.

Groundwater containing selenium enters the wastewater system through cracks or holes in mostly clay pipes that are 75-100 years old. The holes are mainly on the top portion of the pipes, because connections over the years have been made by knocking a hole in the pipe and sticking another pipe into it, Keller said.

Unlike water service lines, the sewage lines are under gravity flow, which means that during dry times, the water is unlikely to leak out, although there could be some cracks in the bottom of the line, she said.

But during wet times, the concentration of selenium increases in all types of water, and groundwater rises and puts pressure on the pipes, infiltrating the sewer system.

The city is lining pipes in the western part of Pueblo, where selenium is most prominent. Levels in the groundwater reach up to 8,000 parts per billion in one test well — more than 500 times the stream standard of 14.1 ppb.

During dry to moderate times, the release level from the city’s wastewater plant is between 12-20 ppb.

“If we have a storm, it will go up to 60 ppb,” Keller said. “Yet even when we’re high, the river is higher yet.”

According to scientific studies, the toxicity of selenium in Pueblo’s water is counteracted by sulfates, which are naturally occurring in the same geologic formation, Keller said. No evidence of widespread harmful impacts can be found.

Pueblo is in the process of lining sewer lines and manholes on the West Side, and evaluating the impact. But that will take 10 years to complete, and the state Water Quality Control Commission has set a two-year deadline to develop a numeric standard, called a discharger specific variance, for Pueblo’s wastewater plant.

“The tests we’re doing will have some impact, but there won’t be enough data,” Keller said. “You need a wet period, but don’t know if we’ll get it. We won’t have enough data to make everyone comfortable.”

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