Unalaska, AK – The city is planning to build a new water treatment plant in Pyramid Valley in order to comply with new federal regulations. The 30-year-old plant needs an additional water disinfection system added to the current chlorine system before October 2014. The project will cost the city about $6.5 million and city staff are seeking grants to help with the cost.

City water supervisor Clint Hulling explained they will install a UV light system that can kill small organisms that the chlorine cannot. That includes cryptosporidium, a cyst that reproduces in the intestinal track of mammals. It only causes diarrhea in healthy people but can have more serious effects in people who are undergoing chemotherapy or have other immune system problems. There is no treatment for the infection. Hulling says the organism is not a problem in Unalaska. After a year of twice monthly tests on the filters that clean hundreds of thousands of gallons of water, only two cryptosporidium cysts were found.

"Normally it takes more than 2 [to cause illness]. The average person would pass two through and probably not even know it," he said. "But the regulation is designed to kill cryptosporidium so that if there is a large quantity of it that hits the water, it won't ever get to the people."

The new plant will include space for the beds of UV lights, the chlorine system, work areas, and a larger back up power generator. It will also include a water turbine, which will make use of waste power and reduce the electric costs to run the plant.

"The pressure coming into the plant is about 110 pounds and we need to break it to about 40 pounds. So we have quite a lot of wasted energy running through our pressure reducing valves right at the plant," Hulling said. "And that is energy that could potentially be used for an electrical turbine to create power."

How much power it can create depends on the time of year. During slow months, like December and May, the plant only treats 1.2 million gallons per day. During peak fishing seasons, it rises to 7 to 8 million gallons per day. Hulling said that requires the city to pull water from all of the wells and from the lake in Pyramid Valley, making water conservation especially important in the winter months.

"In the winter time, we know that there are people who run the water in their house to keep it from freezing, and that is definitely not in the community's best interest," he said. Hulling suggested residents install heat tape or improve home insulation instead.

The city aims to finish the pre-design of the plant within the next few months. The public utilities department will discuss water filtration systems with the council at an upcoming meeting.