An Idea for Preserving the Reservoirs, Creating Energy, and Raising Revenue

By Amy Peterson PSU School of Architecture student

Since 1894, Mt. Tabor Park has hosted open air reservoirs for drinking water for the City of Portland. As part of the Long Term 2 Regulation invoked by the Environmental Protection Agency in 2006, the city cannot use the open reservoirs for our water. The city has built an underground reservoirs as a replacement for the drinking water storage. Proposals for the defunct reservoirs range from burying them to creating skate-parks. These solutions completely transform the character of the historic infrastructure. Many community members would like them to remain filled with water to maintain the historic character. This option requires significant annual maintenance and the costs that go along with it.

Graduate students from the PSU School of Architecture propose an alternative plan for the future of the reservoirs. Mt. Tabor Park could support a small geothermal power plant. In addition to power, the plant would produce large amounts of hot water and steam. These by-products could be used to fill and heat one or more reservoirs to create the Mt. Tabor Thermal Baths. These baths would provide year round, hot water swimming and soaking. This proposal generates low cost energy for the park and community; keeps the reservoirs filled with water; creates a remarkable bathing experience; and generates revenue for the park and city. While a community thermal bathing facility would bring something new to the city it is hardly a new idea.

The Blue Lagoon, a large geothermal bath in Iceland, shows the potential cultural and economic value of a similar facility at Mount Tabor. The lagoon is Iceland’s most visited tourist attraction with hundreds of thousands of people traveling to the site a year to bathe in the therapeutic aqua water. The lagoon was created in 1976 from the over-spill of the Svartisengi geothermal power plant. The geothermal brine, or seawater, is pumped up from 200 feet below ground at 460°F and used to create electricity and hot water for the surrounding towns on the Reykjanes Peninsula. The water is then pumped out onto an old lava field creating the lagoon.

Sutro Baths, a similar scaled attraction as Blue Lagoon, was the largest saltwater swimming facility when it was opened in 1896. Located in what is now in Lands’ End of Golden State National Park in San Francisco, CA, this swimming facility became a popular attraction for people of diverse economic backgrounds, who accessed the site from inexpensive passenger steam train offered as part of the experience. The swimming facility was divided into six saltwater pools that were supplemented with water from tides or pumped in at low tide. The largest pool was kept at the natural temperature of the seawater with the five other pools heated to varying temperatures for the visitor.

The proposed Mt. Tabor Baths would be heated as part of a small geothermal plant located within the park. Geothermal power plants produce energy by a process of pushing a combination of steam and super-heated water, pumped miles underground, through turbines to generate electricity. When only the steam is used in the system, it is called a dry steam power plant. A flash system releases the pressure on remaining separated super-heated water to generate more steam to repeat the process. A binary system transfers the heat from the super-heated water to a secondary fluid, isopentane, pro-pane or ammonia, with a lower boiling point through a heat exchanger to power the turbine. A binary system can be used after a flash system or with lower temperature water making the system more efficient.

Overview of the proposed cascading soaking pools between reservoirs 5 and 6. Designed by Jennifer Moran

Geothermal Power Plants are relatively economical. The energy created through geothermal resourc-es is a renewable energy source and is not effected by environmental circumstances such as other sustainable energy production as with wind and hydro-power. There are two geothermal power plants in Oregon, Neal Hot Springs in Malheur Country and OIT Geo-Heat Center in Klamath Falls. The plants are small quiet and only emit hot water and steam.

While there is still a great deal fact-finding to do (geothermal viability, cost, and revenue) the idea to keep the reservoirs filled and provide a wonderful community amenity remains a provocative one.

Source: U.S. Department of Energy