Project Overview & Important Facts

The Taylors Ferry site currently supports two reservoirs and an operations and maintenance building, which was previously the Metzger Water District main office. Both reservoirs are in need of seismic upgrades. To best plan for future water demands, and improve overall site safety and seismic resiliency, TVWD will replace the reservoirs with matching, 1.75 million-gallon pre-stressed concrete reservoirs that are seismically resilient. 

The existing facilities were designed and constructed prior to knowledge of the seismic risks associated with the Cascadia Subduction Zone (CSZ) and are subject to collapse during a CSZ code level event. This proposed project will eliminate and/or substantially reduce these risks by replacing the reservoirs and operations and maintenance building with facilities designed to survive a 9.0 magnitude earthquake. 

This project will accomplish the following:

1. Seismically upgrade the existing water piping serving the site's reservoirs, both on and off the site, to ensure the water system is functional and complies with current seismic codes and standards. New transmission mains will be zinc-coated ductile iron with polyethylene encasement. 
2. Seismically upgrade the 2.3 million gallon (MG), steel, non-seismically compliant reservoir by replacing it with a 1.75 MG code compliant reservoir. The foundation and structure of the replacement reservoir will be designed and constructed to comply with current seismic codes and standards. 
3. Seismically upgrade the 1.0 MG, concrete, non-seismically code compliant reservoir by replacing it with a 1.75 MG seismically code compliant reservoir. The foundation and structure of the replacement reservoir will be designed and constructed to comply with current seismic codes and standards.
4. Demolish the non-seismically code compliant operations and maintenance building, replacing it with a seismically code compliant building to store equipment and materials for faster emergency response times in the Metzger area. 
5. Seismically upgrade the water service to the 643 pressure zone (the highest topographic area of Metzger) by installing a pumping station to generate water pressure for the higher elevations and equipping it with a 175 kW backup power generator, ensuring the 643 pressure zone can receive potable water following a seismic event.

Why prestressed concrete reservoirs?

Prestressed concrete reservoirs have emerged as a preferred solution compared to other cast-in-place methods. Prestressed reservoirs are constructed by combining concrete with sturdy metal components, including a shell made from wraps of steel strands. This gives ample support and makes the reservoir much more long lasting. The use of high-tension steel wire covered in shotcrete help to prevent corrosion, which can destroy a reservoir over time and make it less effective. The steel strands help ensure a water tight design and inhibit the possibility of leakage. These reservoirs are secure in the face of earthquake-related disasters.

Once completed, the new reservoirs are expected to serve the Metzger community for the next 100 years before needing replacement. 

Why is a pump station needed now?

Traditionally, the Metzger portion of TVWD's service area has been served via a direct connection to the Portland Water Bureau's system. This system also uses pumps to lift water to a reservoir system. Portland's system requires seismic upgrades as well. In addition to seismic concerns, TVWD also plans to move away from utilizing Portland Water Bureau as a source of supply starting in 2026 when TVWD transitions to a new water source in the mid-Willamette River. The pump station at the Taylors Ferry site will allow TVWD to directly serve the highest elevations in the Metzger area. 

The pump station will be fully enclosed to reduce noise, which is expected to be similar to a household air conditioner's noise level. The change to serving these customers via a pump station will be a large improvement in seismic resiliency when compared to the current model of water service for the area.