The Mesa Water District board took a step Thursday to reduce the estimated cost of replacing its pipeline system.
With newly adopted methodology, district staff estimates the 100-year replacement cost at $131 million — down from $200 million under the former standards.
A previous resolution the board adopted in 2014 to guide its pipe replacement policy required testing pipe thickness and outside pressure before replacing a pipe. Using the 2014 methodology, the estimated cost of pipeline replacement over a 100-year period came to $200 million, including $62 million in the first 30 years.
However, the water district found some discrepancies the resolution did not address, according to a staff report. For example, some pipes that seemed to be wearing thin hadn’t broken and indicated they had years of useful life left. Useful life is determined by water pressure, a pipe’s material and thickness and how it is used.
Of the 317 miles of pipeline in the Mesa Water District, breaks related to the condition of pipes occur 16.4 times per year on average, according to the staff report’s assessment of data from the past five years.
In August 2017, a spate of 10 breaks and leaks in the system resulted in $240,728 in repair costs for the district. Officials attributed the rash to “an atypical closing of a system valve” that “resulted in a pressure surge that affected older parts in the system.”
The new resolution the board unanimously approved Thursday tweaked the original replacement policy to consider the history of pipeline breaks as well as a pipe’s useful life estimate.
“This is ... to fine-tune our program going forward,” said Mesa Water General Manager Paul Shoenberger.
In 2014, about 74% of the district’s pipe infrastructure was made of asbestos-cement pipe, with an estimated average useful life of 142 years. With new testing methods the district is using through its pipeline integrity program, the estimated average lifespan has increased to 164 years.
The resolution will return to the board for review in five years.