The City of Prescott and Johansen Construction Inc. have started to rework a section of the Prescott water pipeline through Chino Valley that didn't meet engineering specifications, according to Chino Valley Public Works Director Stu Spaulding.
About a 3,000-foot section of the 36-inch pipeline on ranch land southwest of the Highway 89 and Outer Loop Road intersection failed compaction testing earlier this year.
A recent series of tests uncovered voids, or air pockets, under and alongside the pipeline where inspectors found no soil supporting the pipe that carries water from Chino Valley to Prescott at a pressure of 400 pounds per square inch (psi).
Spaulding said his department accepted a proposal from Prescott that involves taking out the soil currently around the pipe, widening the trench for safety, and replacing soil using proper compaction methods that will result in the specified 95-percent compaction.
Chino Valley is permitting the city to compact the topsoil at a lesser, 85-percent compaction, so the landowner can re-seed the ranch land area.
Chino Valley, City of Prescott, and Arizona Department of Environmental Quality (ADEQ) officials watched as Engineering and Testing Consultants tested the first section of re-compacted earth.
Spaulding said he expects Prescott to complete re-compaction of the pipeline in the ranch land area within two to three weeks.
In that same time period, he expects the City of Prescott to develop a proposal to re-compact the pipeline trench near roads 4 South and 1 East to the required 95 percent compaction level.
It was in that area that Chino Valley citizens first noticed settling of as much as four feet in the pipeline trench after a rainfall this past November.
If the soil around the pipeline had been compacted to 95 percent, even a severe rain would not have caused that settling, Spaulding said.
At that point, ADEQ entered the picture. Liaison Peter Foster has negotiated with Prescott and Chino Valley officials since then about reworking trench areas that don't meet the 95-percent compaction specified in the City of Prescott's contract with Johansen.
The Northern Regional Office of ADEQ has not issued an "approval of construction" on the pipeline project because of compaction problems discovered in the Chino Valley three-mile section of the 13.1-mile pipeline. Johansen Construction completed the pipeline in July 2000.
"You mean the City of Prescott is pumping water through that 36-inch line without approval from ADEQ?" asked Chino Valley Council Member Joel Baker.
Spaulding said because the two municipalities agreed to negotiate a settlement, ADEQ issued no fines or notices of violation.
He told council members he believes compaction problems can be corrected while the pipeline continues to carry water from the city's Chino Valley wells to Prescott.
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