Sean C. Morgan
The Sweet Home City Council on June 11 approved a $311,000 contract with Brown and Caldwell, Inc., to plan upgrades and an expansion at the Wastewater Treatment Plant.
The city has been working on reducing inflow and infiltration into its sewer system since 2001 when it hired Brown and Caldwell to develop a plan to address the problem.
Inflow and infiltration is stormwater that enters the sewer system through cracks in sewer pipes and through cross connections with drainage systems. During heavy rainstorms, the excess water can overload the treatment plant, forcing the city to bypass untreated wastewater into the South Santiam River at Ames Creek.
Based on its analysis in 2002, the city handled 1 million gallons of wastewater per day during the dry season. During a five-year storm at peak flows, the city would receive wastewater at a rate of 22 million gallons per day. Following an expansion in the 1990s, the plant could handle a maximum of 7 million gallons per day.
In lieu of fines, the city entered into an agreement with the Oregon Department of Environmental Quality to eliminate the bypasses. The deadline on the agreement was January 2010. To meet that requirement, the city would need to reduce inflow and infiltration by 15 million gallons per day.
Brown and Caldwell estimated the cost of the effort at $30 million by rehabilitating the sewer lines, said Jon Holland, an engineer with Brown and Caldwell. A plant expansion to handle 25 million gallons per day would cost about $17 million.
The sewer system was in bad shape, Holland said, and it was tough at the time to find its equal among similarly sized communities. The city might have simply upgraded the plant, but it would have left the sewer system in bad shape.
The city chose to work in the sewers, Holland said. TV inspection of the sewer system located old, crushed and broken concrete pipes, and even the newer plastic pipes had leaks and roots growing through them.
Prior to the first phase of the project, Holland said, the pipes were collecting 22 million gallons per day. By the end of phase two, the pipes were collecting just 16 million gallons per day. Phase three cut the rate to 13 million gallons per day. After the completion of phase four last year, the system collected 10 million gallons per day.
The city must reduce that total by at least 3 million gallons per day to meet its agreement with the DEQ.
“You’re doing better in compliance, but you’re not there yet,” Holland said. “You’re not alone.”
And that has helped keep Sweet Home off the enforcement radar with the DEQ, he said. About one-third of the sewer system has been rehabilitated, at a total cost of about $12 million.
“Your story of 60 percent I&I reduction is quite remarkable in our industry,” Holland said, and Brown and Caldwell learned from it. “You can’t just fix the mains, nor can you fix the service laterals. You have to do them both.”
In some basins in Sweet Home, the projects have reduced I&I by up to 80 percent, he said.
The returns for further work in the sewer system would likely suffer diminishing returns, Holland said. Reducing I&I through sewer rehabilitation will be too slow and too costly.
Just replacing two-thirds of the lines on a 50- to 100-year cycle will cost $250,000 to $500,000 annually, Holland said. Meanwhile, the plant is getting old and in some areas “held together by wire and duct tape,” and the time is past for upgrades.
In addition to meeting agreement with the DEQ, the plant also may require improvements and expansion to meet regulations, such as pending turbidity requirements and potential changes in peak flow treatment, said engineer Dan Laffitte. Existing options may include split treatment, with a “wet-weather” facility that operates during peak flows or duplication of the existing plant.
Requirements for complete duplication are pretty far out in the future, Laffitte said, if they’re ever required at all.
The expansion also should include room for growth, not just the final 3 million gallons the city needs to handle under the DEQ agreement, Holland said.
The council voted 5-0 to approve the contract. Voting yes were councilors Craig Fentiman, Bruce Hobbs, Greg Mahler, Scott McKee Jr. and Dave Trask. Marybeth Angulo and Mayor Jim Gourley were absent.
In other business the council:
n Learned that Comcast has expanded its Essentials programs to include families with children at private or parochial schools or with home-schooled children. Families are eligible for the program if they are eligible for free and reduced-price lunches at school.
That includes 63 percent of families in the area, said Tim Goodman of Comcast.
Goodman also presented a check for $500 to Rose Peda, director of the Sweet Home Public Library, to help fund the Summer Reading Program along with a netbook to be used as a prize in the program.
n Approved street closures from 8 a.m. to 4 p.m. on Wednesdays from June 26 to July 31 for the Sweet Home Public Library’s Summer Reading Program in front of the library on 13th Avenue.
n Appointed Brena Barnett to the Youth Advisory Council. She is a freshman completing her education through Insight K12. One position remains open. Contact the city manager’s office at (541) 367-8969 for further information or to apply.
n Approved an amendment to the city’s agreement with the Oregon Department of Transportation regarding the exchange of federal grant funds for state funds at a rate of 94 cents per dollar. With the exchange, the city is not bound by federal requirements for local street projects. The funds have not been used yet, and the amendment will extend the expiration date of the contract from June 21 to June 21, 2015.
n Held the first and second reading of an ordinance amendment revising the Flood Insurance Map and Flood Insurance Study.