Effluent may water grass

If the city of Spokane is going to have to spend $500 million to improve the quality of treated wastewater going into the Spokane River, officials say it makes sense to keep some of that water out of the river and possibly use it for irrigation during warm-weather months.

Other communities recycle their heavily treated wastewater; Spokane will be able to do the same once it completes upgrades to a more advanced level of treatment at the city sewage plant on Aubrey L. White Parkway.

This summer, city officials want to experiment with using “class A reclaimed water” for irrigation on nearby Downriver Golf Course. If successful, reclaimed water could be sprinkled on nearby parks and cemeteries someday.

New pipes and sprinkler heads recently were installed on a small patch at Downriver for an experimental project.

“This is going to be a small pilot to give us an idea of what to look for when we ramp up,” said Dale Arnold, wastewater director for Spokane.

The sixth hole, which has a steep uphill fairway now, is being realigned with the tee and new fairway being moved to the upper portion of the course to accommodate the test.

Golfers who have heard about the project are supportive, said Steve Conner, golf pro at Downriver.

“There is a lot of excitement over the new hole.” Conner said. “Everybody I’ve spoken with thinks it’s a great idea.”

The realigned hole will replace a tee mat with a 40-yard-long grassy tee area at the head of the new fairway.

Purple-colored irrigation pipe – purple is used to distinguish it from pipe carrying potable water – was installed by wastewater and golf crews in the cooperative project. Even though the water is safe to use in irrigation, it is unsuitable for consumption.

It contains dissolved salts and tiny amounts of phosphorus.

Three newer types of grass that are more tolerant of salts are being planted to measure which performs best with the reclaimed water. A patch of old grass also will be irrigated with the filtered wastewater to see how it reacts.

Golf officials said it makes sense for them to cooperate in the project because courses use a lot of water and officials need to be conscious of water conservation.

The golf courses can be good public stewards by participating in water reclamation, said Pamela McKinzie, manager for the city Parks and Recreation Department golf courses.

“If this works, then our industry is helping,” she said.

The Downriver project will be marked for the public, and the purple-pipe irrigation will occur overnight before play begins to avoid any direct contact with people.

“We will have signs partly to educate and partly as one more safety item,” said Lars Hendron, wastewater engineer for the project.

Downriver uses 500,000 gallons of water a day during the heat of summer, while the wastewater plant can treat up to 44 million gallons of sewer water a day, Arnold said.

As with most of the improvements being planned in the city’s sanitary and storm water sewer system, the price of this water reclamation experiment is not small. The cost of the pilot program over two years is budgeted at $700,000.

“We’re stepping into this cautiously and evaluating as we go,” Hendron said.

Effluent water from the sewage treatment plant will be transported by tanker truck to a small portable filter at the golf course. The portable filter, which is being acquired for the pilot project, will work the same as the advanced filtration being installed at the plant.

In addition, the wastewater utility is expected to hire a consultant to test and monitor the experiment, operate and maintain the system and evaluate and report to city officials on how it works.

If this year’s effort is successful, a similar pilot project may be conducted next year at the Creek at Qualchan Golf Course along U.S. Highway 195 in southwest Spokane.

If the city decides to implement the use of so-called “purple pipe” for reclaimed water, it likely would build transmission lines to Downriver and other locations. Some abandoned water lines could be used as conduits.

Hendron said the goal is to reclaim enough of the class A effluent to meet Clean Water Act standards under an agreement reached last year between local governments and state and federal environmental regulators for reducing phosphorus emissions into the Spokane River.

Phosphorus, which is used as a fertilizer and is a natural byproduct of human waste, is considered a pollutant because it acts like a nutrient when released into the river, causing algae to bloom, which, in turn, depletes dissolved oxygen needed for healthy fish populations, particularly in Lake Spokane.

Treatment technology removes 90 percent of phosphorus coming into the sewage plant now, but a residual amount of 730 parts per billion of phosphorus remains in the effluent going into the river.

The city is proposing construction of sewage “clarifiers” with advanced filtration to remove about 90 percent of that phosphorus, reducing the concentration to less than 75 parts per billion. The cost is estimated at $136 million.

Hendron said that even with advanced filtration, the city may not be able to achieve sufficient reductions to bring the river back to phosphorus standards being set through the state.

“We are chasing the last few pounds of phosphorus,” he said.

Water reclamation could help the city achieve those standards.

Other cleanup efforts are being made as well.

Last year, the state banned phosphorus in dishwashing detergents, and there has been talk about banning phosphorus in lawn fertilizers.

In addition, two new egg-shaped digesters, pumps, pipes and odor-control measures are expected to cost $123 million. The new digesters are under construction.

New underground storm water storage tanks are being planned to catch a mix of sanitary sewage and storm water that comes from sewer lines mostly off the South Hill and downtown Spokane.

During big storms, those lines are designed to overflow into the river to prevent the sewage plant from being inundated. The idea is to catch that excess in tanks and pump it to the sewage treatment plant after the storm subsides.

The cost is at least $175 million.

The effect on rates already is being felt. Ratepayers are paying an additional $13 a month to finance the improvements, and city residential sewer rates could increase to about $49 a month when the improvements are completed by 2018.