Turlock, CA Uses Shot Crete for Its Irrigation Ditch Because It Works – Another Statement to Ashland Council from a Citizen
I’m not going to go over the irrefutable facts that I have already given you about E. coli. I think that I’ve filled your ears and in-boxes enough already. What I will say is that the authors of the study understood that it had limitations which is why I believe they recommended further study. As an aside, there was DNA testing performed in 2007 to identify human vs. animal contamination. No human isolates were positively identified.
Instead I’m going to tell you about a phone call I had last week.
It is a common practice to use fiber reinforced concrete applied via the shotcrete method for the repair and maintenance of irrigation canals as happens in Turlock and Modesto, California. I had a long, informative conversation with engineer Matt Hazen from Turlock about a canal rehabilitation project that was completed in December 2018. They relined 5,737 feet of open canal with fiber reinforced concrete that was sprayed over the existing liner. 5-10 miles of the 250 miles of open canal are rehabilitated each year. It is expected that the new lining will last a minimum of 50 years. The cost of this project was approximately $500,000.00 or $4.50/square foot. This part of California is climatically different than Ashland in that it does not get as hot in the summer or as cold in the winter.
The Bureau of Reclamation performed some testing of different canal linings. One material that was used was shotcrete with and without polyfibers. The conclusion drawn from that study for concrete, aka shotcrete, was a life expectancy of 40-60 years, and that the condition of “shotcrete with polyfibers” was in excellent condition after 10 years with “no problems”. Several of the test areas were in the Bend, Oregon area and a part of the Arnold Irrigation District. The specified thickness of the shotcrete was 3 inches and after 9 ½ years there was no freeze-thaw damage observed. Bend is typically colder than Ashland during the winter months.
All three alternatives that sit before the council involve the destruction of the current canal. One option also includes the dismantling of private property in order to unearth the sections of pipe that are currently in place. My desire is to ask council to table the current discussion in order to have the experts in the Public Works department thoroughly look at the option that includes the use of fiber reinforced concrete applied via shotcrete. As an individual who owns property along the irrigation ditch, an option that would be less disruptive to the land and to homeowners along the canal, while preserving a valued resource for the city, is one that is well worth looking into.
Julie Bonney, Ashland