By DAVID TELLER
Staff Reporter
Every gallon counts.
The current water situation in Cheney is such that the water production from the city's seven operational wells isn't producing enough water to support the proposed developments.
The city has already sunk a test bore and has enough positive results to build a new well.
The existing wells can contribute more.
During the last council meeting, the city approved more than $230,000 to CH2M Hill for engineering and construction administration service for wells No. 6 and 8.
Not only does the city intend to increase the size of well No.6, but also its efficiency.
The well is going to be redeveloped from a 12-inch diameter shaft to as much as 20 inches in diameter.
The current size of the well limits how much can be pumped from it.
The current depth of well No. 6 is currently 710 feet.
The redevelopment will expand the diameter of well No. 6 from the surface down to 420 feet.
Don MacDonald, Cheney's public works director said the well hole was originally drilled at an angle.
Without a linear well hole, a submersible pump must be used.
An above-ground pump cannot be used because of the non-linear direction. He added the city has learned the hard way that the pump has to work a lot harder.
Part of the new hole will be drilled linear to maximize pumping efficiency.
The straight well hole will also relieve maintenance demands because the pump will be at the surface and will be more accessible.
Drilling the hole is another topic.
Stratigraphy is a branch of geology studying rock layers.
MacDonald said there are enough stratigraphic similarities between wells No. 6 and 8 that the city's consultant, CH2M Hill, is recommending drilling a new well hole at the well No. 6 site to a depth of approximately 455 feet below ground surface (bgs) for both wells.
According to the test bore data from well No. 8, it appears the optimal location for producing the most water at both well sites is in the area between 290 feet bgs to 455 feet bgs.
“We will rely on the expertise of our consultant to outline the appropriate drilling method in the specifications,” MacDonald said.
He added there are drilling methodologies that are geared toward drilling a linear well hole, and most notable would be through a cable-drilled well hole rather than a rotary drilled well hole.
According to Oilfield Glossary website, cable-drilling is a method of using an impact tool or bit, suspended in the well from a steel cable that is dropped repeatedly on the bottom of the hole to crush the rock.
The tool is usually fitted with some sort of cuttings basket.
This device traps the cuttings along the side of the tool so material sloughing into the hole shouldn't be a problem.
After a few impacts on the bottom of the hole, the cable is reeled in and the cuttings basket is emptied, or a bailer is used to remove cuttings from the well.
The tool is reeled back to the bottom of the hole and the process is repeated. Though largely obsolete, cable-tool operations are still used to drill holes for water wells.
Work has not yet begun on well No. 6.
MacDonald said until the city needs to tie the new well hole into the transmission main Cheney can continue to operate the current well No. 6 hole which is typically used during the irrigation season.
Completion is scheduled just in time for the dry season in summer 2008. MacDonald plans to have the new well hole in operation by July 1.
“I would certainly imagine that short of an extremely wet spring that we will be operating the existing well hole before work on the new well hole is completed,” MacDonald said.
David Teller can be reached at [email protected]
Reader Comments(0)