Second Ball Park well ready for testing in February

Published 4:08 pm Thursday, April 30, 2009

By Dennis Box, The Courier-Herald

The city of Bonney Lake has drilled a second well at its Ball Park site, about 500 yards from the first well on the north side of the Emerald Hills Elementary. The drilling, completed by Holt Drilling Inc., goes down 240 feet, the same depth as the first Ball Park well.

Bonney Lake's water right for the Ball Park site is 1,270 gallons per minute. City engineers are expecting the second well to pump about 300 gallons per minute, while the first well pumps 1,000 gallons per minute. Once both wells are functioning at capacity, the usage will be carefully calibrated to produce the 1,270 gallons per minute the water right allows.

With the drilling completed, the next step in the process is a 72-hour test to check the aquifer while both wells are pumping. The test is planned for February, during the elementary school's mid-winter break.

The water in both wells must stay at a designated level above the pumps or "cavitation" takes place, which is air getting into the pump.

"The pump has to be far enough down so it stays submerged," city engineer John Woodcock said. "Water is basically not compressible, but air is. Air molecules are far apart, that's why you walk through air, but water molecules are much closer together, it's much more dense. If we start pushing air up the system the pumps will break down. We don't want to get to the point where the aquifer is drawing down allowing air into the pumps."

The drilling and maintenance of a municipal well is considerably more complex than a well serving on home or a few homes. An exploratory well is drilled first, a couple of inches in diameter, hundreds of feet into the earth, to find the aquifer.

Once the water is found, a four- to six-inch well is drilled. Steel casing is put in place with screens at the bottoms for rocks. A submersible pump is lower into the well. The motor is rigged above and wiring connects them. It is critical the well be drilled dead-on straight or the pump will hang when lowered, and there is no way to reach down and knock it loose.

The pump is lowered into the water because it is easier to push water then to try to pump it up. "When you drink soda through a straw you suck on the straw and it creates a vacuum," Woodcock said. "But if the straw is 70 feet high the vacuum breaks down. The farther the pump is from the water source the harder it is to pump, so you put the pump into the water and push the water through the well casing."

The Ball Park wells are drawing from an underground lake. Where the lake comes from and its true size can only be guessed at.

"It's being recharged from somewhere," Woodcock said. "But it's not an endless supply. This past summer should tell us we have to be careful and conserve. We will have to always be looking for new sources."

Along with the new well, a filtration plant will be built at the site to filter out the high levels of iron and manganese from the water.

"The Ball Park well was used only at peak periods because of minerals present in the water," Mayor Bob Young said. "The water doesn't taste that great and it looks bad. We have to clean up that water because our citizens are used our own water that tastes and looks good."

The filtration plant will begin construction in late spring or early summer of 2004 when school is out. The second well and filtration plant will be ready for full operation in 2005.

The Ball Park wells are one of four water systems supplying the area. Victor Falls Springs, Tacoma Point Well field and Grainger Springs also supply water.

Dennis Box can be reached at dbox@cmg-northwest2.go-vip.net/courierherald