Corroding sewer a reminder of the Casper that never was

Corroding sewer a reminder of the Casper that never was

1980s boom

Roughnecks work on an oil rig in this early 1980s photo from the Casper Star-Tribune archives. Casper built its North Platte sewer line in 1980 anticipating the boom would continue and the city would see ongoing growth. That didn’t pan out, and now the pipe is dangerously under-capacity.

Everyone uses the toilet. And in the 1970s, Casper was expecting a lot more toilets.

Casper was booming as an Arab oil embargo drove up domestic prices. The city grew roughly 20 percent between 1970 and 1980.

The city built a new sewer pipeline in 1980, expecting the population to continue skyrocketing.

“It’s the main line and quite a large line,” explained City Manager V.H. McDonald.

But Casper had only 51,000 residents at the time, and when the nine-mile North Platte Sanitary Sewer opened in 1983, the Oil City’s population was slowly starting to deflate. Just three years later oil prices had fallen by more than half from the start of the decade.

Simply put, there were fewer people left to fill up the city’s new sewer pipe transporting wastewater from west Casper to the water treatment plant.

That posed a problem.

With less water being treated and sent through the pipe, the sewage took longer to flush through the system. The longer it stayed in the pipe, the more hydrogen sulfide built up.

Hydrogen sulfide naturally occurs in both crude petroleum and the human gut. For Casper, as crude petroleum production tapered off, it was the chemical’s production in the guts of residents that became an issue.

The chemical is a colorless, poisonous gas that smells like rotten eggs and, most problematic for Casper’s sewage system, causes concrete pipes to corrode.

Given that Casper’s population didn’t even break 50,000 again until the new millennium, the North Platte pipe has remained below capacity for over 30 years.

“There’s not enough flow in that pipe,” said Casper public utilities manager Bruce Martin. “The longer that (sewage) is in there, the more likely it is to create hydrogen sulfide.”

Since the late 1980s, the city has flushed clean groundwater into the pipe during summer months, when warmer water helps dissipate the corrosive chemical, Martin said.

For a period in the early 1990s, the city pumped lye into the water, which lowered its acidity and helped with the corrosion problem. But like other acids, lye can cause severe chemical burns, and Martin said its use was discontinued out of safety concerns.

After an assessment of the pipe was conducted four years ago, the city began to realize the urgency of solving the corrosion problem, Martin said.

Last year, the city enlisted local contractor CH2M Hill to build a new facility attached to the pipe that will dispense iron chloride to address the corrosion.

But the facility was engineered to higher standards than necessary, and public services director Andrew Beamer was back before Casper City Council in early December to amend the plans.

“(This is about whether) we’re building a little brick house or a shed to store the equipment,” mayor Daniel Sandoval offered.

Scaling down the plans to build the shed rather than the house will cost roughly $33,500 more in engineering costs but save $100,000 to $150,000 in construction costs, Beamer said.

The total cost of the project is $162,800.

Beamer said building the facility was the most affordable way to take care of the corrosion.

“If we didn’t put this treatment system in place, we would have to be replacing, over time, portions of the sewer,” Beamer said.

Sandoval pointed out that there was a low-tech solution to the hydrogen sulfide problem.

“There were discussions of just venting it,” Sandoval said. “How would you like that smelling up your neighborhood?”

The change to the corrosion prevention facility was unanimously approved. Council member Kenyne Humphrey said the new plan showed city government at its best.

“This is focused on city services, but it’s not sexy,” Humphrey said. “This is what we’re doing. This is what doesn’t make it to the paper.”


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