About four miles of Kennewick Irrigation District's main canal and almost two miles of the Badger East canal will be rubber lined when irrigation water pours into the system in April.
KID field crews are almost finished with the second phase of a multimillion-dollar project that is expected to conserve water, make the canals less susceptible to failures, reduce weed problems and save on general maintenance.
The last 3,000 feet of canal should be shielded with the 45 millimeter rubber liner within a few weeks, said Ed Everaert, engineering and operations manager.
"One week of good weather, and it'll be laid," he said, leaving plenty of time to anchor the liner with ballast on the bottom of the canal and lock it in place with trenches on each side before water arrives in three months.
Lining the canal sections, both of which are in the Badger Canyon area, has a cost value of about $5.5 million.
About $1.5 million is expected to come as a grant from the U.S. Bureau of Reclamation, with $4 million from KID.
Chuck Freeman, district manager, said the majority of KID's share is in labor, fuel and equipment.
The out-of-pocket cost to KID is about $1.5 million, all of which will come from the canal upgrade and infrastructure fund, previously called the canal rehabilitation fund, said KID treasurer Colleen Storms.
Using KID employees helps dramatically cut the cost.
"We are able to line many more feet by having our own people do the work," Freeman said. The project cost would be $1.75 a square foot installed by a contractor, but the cost to KID is about $.75 a square foot with KID staff doing it.
Everaert said the project also keeps year-round employees busy in the off-season months when there aren't as many work assignments as during the irrigation season. He noted that the rubber liner is a better performing product than either concrete or a sprayed concrete called shotcrete and is much less expensive.
"It is one-tenth the cost of four-inch concrete and half the cost of shotcrete," Everaert said.
The rubber liner also has a life of up to 50 years. KID has a full guarantee from the maker, Firestone, for 10 years, and an additional 10 years of pro-ratable coverage.
Lining a canal is labor-intensive and costly if a contractor is hired, which is why Everaert recommended having KID employees learn to do it. The canal first must be cleared of debris and weeds, then made to a uniform profile to accept the lining materials. The canal bottom also must be dug about 4 inches deeper to allow for ballast to be laid on the liner after it is installed.
Laying a cushion known as a geotextile directly onto the canal sides and bottom is the next step. The flexible fabric separates the liner from dirt and rocks in the canal.
Then comes the rubber liner that is pulled off large rolls of 30- or 35-foot widths. Each 200-foot roll has to be pulled and stretched into position to fit the canal's profile.
Freeman called the task a difficult job, "requiring a lot of effort."
Next comes sealing the joints, which are pressure tested and inspected.
The last step is to put down the ballast and secure the outside edges of the liner by burying it in trenches.
Firestone representatives, including its head engineer for the product, spent a week last spring training KID workers and advising on the first phase of lining Badger East canal and the main canal.
The project this fall with more than three more miles of canal lining completed has gone much faster now that KID crews are experienced in handling the heavy materials, Everaert said.
A KID eight-minute video showing the installation process is at www.kid.org.
Everaert said the obvious benefits from canal lining are water savings and less need for chemicals to control weed growth that is common with unlined and concrete-lined canals.
The manufacturer has determined that a rubber-lined canal loses one gallon of water per day per acre, while the water loss through leakage on a concrete-lined canal is many, many times greater, Everaert said.
But the biggest reason for lining KID's canals is public safety, to prevent leaks in an unlined or concrete-lined canal, which can lead to blowouts. Rubber lining a canal makes blowouts and major leaks less likely to happen, he said.
"The public safety on this is huge," Everaert said.
Another benefit to rubber lining is that he helps speed the water along its way, he said.
"Being slicker means lower freeboard," Everaert said, referring to the fact that water moving faster across a rubber surface through the canal keeps the flow from climbing higher up the canal side walls.
That also is a safety benefit, he noted.
The canal lining effort will continue into 2012 and thereafter as KID engineers identify parts of the system that would benefit from the lining.
Looking ahead and taking Storms' advice, the KID board authorized an early purchase of lining materials for 2012 last fall, avoiding a price increase that would have cost the district $580,000 if the purchase was made later this year.