May 22, 2011 - Bend Bulletin - Arid Prineville finds elusive water
五月 23, 2011
Arid Prineville finds elusive waterBy Erik Hidle / The Bulletin
Published: May 22. 2011 4:00AM PST
Finding water in the Crooked River caldera is now less of a gamble and more of a science.
After decades of drilling unproductive wells, the city of Prineville inadvertently tapped into a fluvial channel, a deep underground stream that once may have served as the path of the Crooked River. That channel could be a significant source of water.
Following the discovery, the city has set about mapping cross sections of the Earth beneath Crook County to determine the path of the underground river. City officials hope to use the map eventually to select locations for wells.
“Where the current high-producing wells are is where the Crooked River was about 8 million years ago,” City Engineer Eric Klann said. “That’s the location the river was in before the lava flow came in and moved the river. It pushed the river out of the way, but it left some behind as well. That’s what we’ve found.”
Prineville Public Works Superintendent Jerry Brummer said the river is as old as the Grand Canyon.
“It’s just been pushed around so much that it’s not as deep,” Brummer said. “Because of that movement, we have a river that is 2 feet deep instead of 5,000 feet deep.”
The best wells are located near the Prineville Airport, a couple of miles west of where the Crooked River runs. Klann said the river likely sat in the area around the airport for a million years before it moved and thus left a water resource intact. The ancient underground stream is found about 400 feet below ground in that area.
But, until recently, the city had no idea why that area was such a good source.
The first well near the airport was drilled in 1996 and was providing about 1,000 gallons of water per minute. Klann said that is considered a high-producing well for the Prineville area.
In 2005, the city drilled three new wells at a cost of $1.2 million to accommodate a growing demand for water. One of those wells was as close as 2,000 feet from the high-producing airport well.
At that time, deciding where to drill for water was largely a matter of guesswork. The three wells came up dry.
“Before, you just had no idea where there was going to be a good well,” said Klann. “That’s how you end up with three dry wells.”
In 2006, the city drilled another well, this one next to the high-producing 1996 well. It also provides 1,000 gallons of water per minute.
But before tapping the well, the city lowered a camera into the hole and found smooth river rocks along the wall of the hole, along with an abundance of fresh, clean water, down to 700 feet. The water could go deeper, Klann said, but the city has yet to drill that far.
Upon making that discovery, the city decided to change its drilling strategy to eliminate dry wells.
“For the past two years, we have been spending a lot of time using the current wells to see what the geology of the area is,” Klann said. “Even the dry wells show us what the geology is there. Every well has a lot of information, and they help us develop those cross sections.”
The cross sections will eventually give the city a rough estimate of where the underwater channel runs. Klann said he expects the underground mapping to be completed in July; he will then brief the City Council. At that point, Klann said, he hopes to drill small test holes around the area to further map it.
“The map gets us on the target,” Klann said. “But once we finish with the tests we will be able to hit the bull’s-eye.”
Mapping the three cross sections is costing the city $16,919, which Klann said is minimal compared with the price tag of drilling an unproductive well.
And for the city, the water means stability and growth.
City Manager Steve Forrester said Prineville needs to provide resources like water and power to attract major companies like Facebook.
“That area (where the underwater stream is located) could end up being a big part of where we develop water to produce growth,” Forrester said. “It is already our best producer now, and we have reason to believe it could be even better. This study will tell us if that’s right. The cost is worth it.”
An update on the project is expected to be presented to the City Council on July 12.
Erik Hidle can be reached at 541-617-7837 or at email@example.com.
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