City plans for water system upgrades

The critical concerns for Sisters’ water system are storage capacity, transmission-line capacities, and aging/undersized infrastructure. Over the next two decades, the City projects investing millions of dollars in the water system.

The Sisters City Council has received a system evaluation and recommended capital improvement projects to the City water system from Anderson Perry & Associates Consulting Engineers and Public Works director Paul Bertagna.

The water system overview evaluated the City’s current capacity to determine an approximate timeline for implementing recommended improvements. The overview addressed three main areas: water supply and treatment; water storage; and water distribution. The primary objective of the water master plan update is to provide the City with an updated comprehensive planning document through the year 2042. It also identifies improvements needed for system growth and to meet regulatory requirements.

The update is intended to modify outdated sections of the 2017 water plan and update the population projections through the 20-year planning period.

The Portland State University Population Research Center publishes population estimates and forecasted growth for Oregon regions, which are used to develop projected demands through the planning period. The 2020 population estimate for Sisters was 3,220. The forecast for 2022 is 3,437, and the 2042 forecast is 6,917.

Those figures help determine average and peak demand on a per capita basis from past records and population estimates. The City’s records show water usage at all four wells daily. Those figures help estimate future needs for water.

The existing facilities include wells 1, 2, 3, and 4. Well No. 1 pump station is old, built in 1975. It needs to be rebuilt and have a new on-site generation system and magmeter. This project is slated to be done between 2022 and 2027 for $755,000.

Construction of Well No. 5 and its transmission line at a projected cost of $2.649 million is slated for 2035-2042. Well No. 3, identified for installation of standby power and a variable frequency drive, is scheduled for 2027-2032, for $369,000.

Current storage of the City’s water is provided by a 1.6-million-gallon storage tank built in 1995. One of the leading projects for the next five years is construction of a new 2.2-million-gallon water storage tank and rehabbing the existing tank to provide redundancy in the system. The tank project is the single most expensive project at $6.133 million.

The water distribution system consists of reservoir transmission lines, distribution system mains, fire hydrants, and each individual place of service. The third most expensive improvement is installation of a new 24-inch ductile iron transmission line from the reservoir to Whychus Creek junction. This $2.537 million project will replace the current 12-inch asbestos concrete (AC) reservoir transmission line.

Replacing all other remaining AC mains is slated for 2027-2032 with a price tag of close to $4 million. This project includes installing a new 18-inch transmission line from Whychus Creek junction to East Tyee Drive and installing a new 12-inch distribution main from East Tyee Drive to East Hood Avenue.

In the next five years, existing 12-inch AC lines in Edge O The Pines and other areas will be replaced with 18-inch mains. Numerous distribution mains will be extended between 2027-2032. Each year between now and 2042, ongoing water service meters replacement will occur at 50 per year, costing $20,000 each year.

The total for all improvements comes to $19.1 million in today’s dollars. Between 2022-2027 total project costs amount to $10.9 million, 2027-2032 is $5.5 million, and 2032-2042 is $2.7 million.

All this future planning will put the City’s water system in good stead for the anticipated doubling of the population by 2042, including providing fire flow capacity, and meeting future flow demands.