City reservoir repaired

The roof of the city water reservoir has been sealed. photo by Gary Frazee

Citizens of Sisters may rest assured that the drinking water from Pole Creek Reservoir is safe from contamination. The city just spent $70,000 repairing the reservoir roof.

"In a few places you could actually see into the reservoir," said Gary Frazee, Public Works Director. "Because of this we had to repair the roof."

The holes in the roof left the water exposed and vulnerable.

"The best case scenario is contamination from rain and snow," said Frazee. "Your worst case scenario is terrorists or who knows what."

The Pole Creek Reservoir is constructed of 40 concrete panels with a like number of joints. The joints on the roof are 55 feet long. The vertical wall of the reser- voir has maintained its structural integrity.

On the roof though, the joints cracked after several seasons of freezing and thawing. The destructive forces acting on the joints were the contraction and expansion caused by severe winter temperatures.

The reservoir was completely drained prior to the repair project. Sisters was supplied with water by one of the two wells: Sisters Middle School well or the Three Creek Road well. With one well running at a time -- at 800 gallons a minute -- there was an extra 500 gallons that the city didn't require. The extra water was diverted into the city's old pond reservoir.

The water from the new reservoir was drained into Pole Creek. In order to do this chlorination had to be discontinued two weeks prior to the drainage. The city water is chlorinated at two to four parts per million to ensure purity.

The city wanted to avoid polluting the stream.

"That's all we needed was to have any fish in there (Pole Creek) belly up," said Frazee.

It took about a week at 100 gallons a minute to drain the reservoir. The reservoir holds 1.6 million gallons of water.

D and R Masonry from Portland was contracted to do the repairs on the new reservoir. After the reservoir was drained, D and R Masonry laid Visqueen all along the bottom floor inside to catch falling debris. Then they chipped out all 39 joints.

Once the joints were cleaned out they were filled with a rubberized sealer and Styrofoam. In addition, three coats of rubberized sealer were applied to the whole roof.

After the joints were repaired the entire inside of the reservoir was disinfected.

The $70,000 to pay for the job was taken out of the city water fund.