The Oakdale Irrigation District has completed a $15 million tunnel that bypasses a section of canal at risk of rock slides.
The 5,949-foot tunnel a few miles east of Knights Ferry is the 10th that OID has built since it formed in 1909 to tap the Stanislaus River.
One machine bored from the east and one from the west after the project launched in September 2017, with a break for the 2018 irrigation season. The drillers met last month precisely where surveyors had planned, General Manager Steve Knell said Monday.
The project was funded by the sale of some of OID’s water to western and southern parts of the San Joaquin Valley, a common practice for the district . It drew criticism from some quarters during the drought, but supporters said the sales have kept water costs down for local farmers.
The mile-long canal section at issue was built in 1912 in an especially steep area of the river canyon. It is part of the South Main Canal, which serves the 60 percent of OID that is south of the river.
Rock slides have happened on “numerous” occasions, a news release said, through rarely during irrigation season. District leaders did not care to take chances anymore.
“It’s just a ticking time bomb on the south side,” then-board member Frank Clark said in 2013.
The district hired Drill Tech Drilling & Shoring of Antioch to bore the tunnel, which is 14 feet tall and 17 feet high. About 73,000 cubic yards of crushed rock was taken by conveyor belt to dump trucks that hauled it to the nearby Ohe Sand & Gravel Inc. for use in an embankment.
The project, dubbed the Two Mile Bar Tunnel, will go into service with the start of the 2019 irrigation season in March.