Comstock area to get 7 dry wells

As part of the city’s massive effort to control sewage pollution in the Spokane River, the city is installing seven dry wells in the Comstock Park area to intercept stormwater before it gets into combined sewer and stormwater lines.

The $240,000 project is being financed by the city’s water-wastewater integrated capital fund.

It is one of the smaller projects in the cleanup effort when compared to the large holding tanks that are being buried at 18th Avenue and Ray Street and at Underhill Park.

The cost of those two combined sewer and stormwater tanks is $12.4 million.

The Comstock-area dry wells are being installed by Stone Creek Land Design & Development, of Spokane, under a $217,000 contract.

Four of the dry wells will be built into the ground along the curving portion of 37th Avenue from High Drive north to Lincoln Drive.

Two more will be in Lincoln Drive near Croydon Court.

A seventh well will be at High Drive and 37th Avenue.

The idea is to intercept storm flow at the top of the drainage basin running down the South Hill. The seven dry wells being sunk into the Comstock area’s sandy soils will allow stormwater to seep into the ground, said Marlene Feist, spokeswoman for the utilities.

Sewer lines in that basin handle both sewage waste and stormwater.

During heavy storms, the lines carry so much combined sewage that some of the flow runs directly into the Spokane River. That prevents flooding at the downstream sewer plant.

During the first three months of this year, the city reported that 43 million gallons of combined storm and wastewater went directly into the river due to a series of storms.

The outfalls where combined sewage enters the river are posted with warnings to the public to not make contact with the water during overflow events and to notify the city if they see an overflow.

Some of the city’s storm sewers were separated from sanitary sewers in the 1980s, but the storm sewers themselves also carry pollution to the river such as fertilizer, oil residue, polychlorinated biphenyls (PCBs) and metals.

The separated storm sewers dump up to 1 billion gallons of water annually from buildings, streets, sidewalks and parking lots directly into the river.

The city could spend up to $500 million through utility charges to complete the cleanup under the federal Clean Water Act.

In addition, the city from 2000 to 2012 spent $200 million on sewer system improvements, including upgrades at the city’s sewer plant next to Riverside State Park.

Engineers at City Hall are increasingly looking toward smaller projects such as the 4-year-old “rain gardens” on Lincoln Street south of Cannon Hill Park to reduce stormwater flows. It is part of an integrated approach to sewers that makes use of less expensive options and doesn’t rely completely on large tanks and plant upgrades.

New rain gardens are being installed along Monroe and Lincoln streets from Ninth to 17th avenues as part of a street construction project. Next year, rain gardens may be used along Havana Street where a street reconstruction project is planned and possibly on a portion of Ray Street where another street project is expected next year. Both are in southeast Spokane.

On the North Side, Gonzaga University engineering students are working with city engineers to design a water infiltration system using porous asphalt on Sharp Avenue through campus, Feist said.