Project Description

Tigard uses aquifer storage and recovery (ASR) wells to supplement drinking water supply during the peak summer demand season. ASR wells also serve as a backup water source when supply from the Clackamas River, the city’s primary source, is reduced. The ASR program allows water to be stored in the ground and withdrawn during peak days.

Two ASR wells have been developed by the city (ASR 1 and ASR 2), and a third ASR well (ASR 3) was drilled and tested in 2007. ASR 1 has been in production since 2001, and ASR 2 has been in production since 2006. Screens and casing were installed in ASR 3; however, the well never has been fully developed into an operational supply well. This project will complete ASR 3 and make needed improvements at ASR 1 and ASR 2.

At the ASR-3 site, co-located with Elizabeth Price Park and Reservoir 16, the work will include construction of a wellhouse, installing a deep well pump, underground piping, electrical and mechanical equipment, and emergency backup generator needed to bring ASR 3 into service. In addition, the ASR 3 well will be rehabilitated before the start of construction. At the ASR 2 site, co-located with Reservoir 10, electrical systems will be upgraded, the well pump will be rehabilitated, and a new on-site sodium hypochlorite generation system will be installed. Lastly, at the ASR-1 site, co-located with Reservoirs 1-1 and 1-2, a new on-site sodium hypochlorite generation system will be installed.

The project will also install a new pressure-reducing valve at Reservoir 4, providing greater water system resiliency and interconnectivity. Modifications to the existing Reservoir 4 will allow for a connection between the 560-foot service area and 410-foot service area. A connection between these service areas will facilitate increased turnover in Reservoir 16 (serving the 560-foot service area) and Reservoir 4 (serving the 410-foot service area), which will allow for improved water quality in each of these reservoirs.

WHY IT’S NEEDED: As the city continues to grow and water demand increases, the city will now develop ASR 3. The Tigard Water Master Plan projected that between 2010 to 2020, the average daily demand in zones that would be served by these wells would increase by 0.63 million gallons per day, and the peak daily demands would increase by 1.33 million gallons per day. As such, the Master Plan called for the development of ASR 3 and modifications to Reservoir 4. Furthermore, both ASR 1 and 2 have historically experienced slight operational issues during use.

STRATEGIC PLAN TIE-IN: This project supports the fourth goal to “fund the vision while maintaining core services” as it will allow for the continued supply of the basic, daily need of clean drinking water to community members. 

TIMELINE: Expected completion in Summer 2024

FUNDING SOURCES: Water Fund; Water System Development Charges Fund. 

OPERATION AND MAINTENANCE COSTS: Operations staff will be able to manage summer peak demands more efficiently in the future. 

CONTACT: Ross Horton: 503-718-2580 |  ross.horton@tigard-or.gov