Higher than average rainfall in recent weeks has not only provided drought relief, but it’s also dampened sewage treatment efforts.
The surplus precipitation, more than 2.6 inches in May, was a topic of discussion for Cortez Sanitation District officials at their monthly meeting on Monday, June 8. In recent weeks, storm runoff has added more than 100,000 gallons of water to the district’s 1.6 million gallon per day sewage treatment facility.
“A 100,000 gallons is a big deal,” said CSD board member Jim Candelaria.
The extra water, known as infiltration (groundwater entering the system through broken pipes, for example) and inflow (water introduced into sewer lines via roof drains or basement sump pumps,) dilutes the treatment process, decreasing the systems efficiency, said CSD superintendent Phil Starks.
“The rain messes up the treatment process,” said Starks. “It complicates the process.”
Because of the dilution, Starks said, the microscopic organisms responsible for breaking down organic materials in wastewater get spread further apart.
“The chemistry, everything changes, and it requires more maintenance,” said Starks.
Drought conditions since the wastewater facility was built in 2006 have made an infiltration and inflow problem a rare occurrence.
“We didn’t realize we had this type of I and I (infiltration and inflow) until we started to get rain again,” said CSD manager Tim Krebs.
Candelaria also raised potential exfiltration concerns.
“If there’s a hole that’s letting it in, then there’s a hole that’s letting it out,” said Candelaria.
While roof drains tied into the sewer system are illegal, finding out where storm runoff enters or exits the sewage system would require hydrology monitoring, complete with rain gauges and flow meters. For years, Starks has pushed for such a system to monitor the districts near 70 miles of sewer lines, but it’s been placed on the back burner, he said.
“The equipment and staff to run it would be $20,000 to $30,000,” said Starks. “It’s something we have to do.”
After board members determined the district’s latest audit indicated enough unrestricted cash reserves were on hand to make the investment, Starks was given the green light to come back with an official proposal.
“I’m trying to fix things,” said Candelaria. “This is significant.”
“The rain is coming back in two days,” said board member John Stramel. “This is serious.”
Despite the pressures on the treatment process, Starks said the plant has continued to operate and meet environmental guidelines. He added the most noticeable difference was the turbidity, or clarity, of the treated wastewater when it exits the facility. Turbidity levels have increased from .8 up to 2.8, said Starks.
“We’re not in violation,” Starks said. “We have a rock-steady system.”
CSD officials indicated that more expensive capital improvement projects were also needed. The most expensive, as high as $500,000, is replacing an antiquated screw press, which is used to extract water from bio solids. With an estimated price tag of $350,000, another pressing need is a new rodder, or septic tank, truck, which is used to clean clogged sewer lines.
“We operate on priority-based budgeting,” said Krebs, indicating that he was actively searching for possible grant funding to help offset the costs.
Stramel stressed the importance of proper planning, stating that price negotiations, for example, could be entered when not pressed for time.
“If we get behind the 8-ball, then we spend more money,” said Stramel.
