The base material is intended to allow groundwater under and around the pool to drain. If it's not fixed, over time the fine material in the aggregate could clog drains and leave voids in the foundation when groundwater rises and drains with summer …
Soil conditions delay pool progress, taxpayers won't pay for costPowell Aquatic Center project leaders are working this week to fix a problem with material used in the pool's foundation. Test results released last week show that the level of fine material in the aggregate — a mixture of gravel, sand and other particles — is too high.
The base material is intended to allow groundwater under and around the pool to drain. If it's not fixed, over time the fine material in the aggregate could clog drains and leave voids in the foundation when groundwater rises and drains with summer irrigation.
“If it gets too clogged, water will not be able to move through,” said Nancy Ronto, the Burbach Aquatics project manager. “It shortens the lifespan of the pool.”
Project leaders assure that it will be fixed — even if that means tearing out concrete that was poured earlier this year.
“That would be the ultimate worst-case scenario,” said City Administrator Zane Logan.
Burbach Aquatics engineers are looking at an effective and less-costly alternative.
Whichever way it is fixed, taxpayers will not be responsible for the cost.
“There's no cost to the taxpayers on this,” said Casey Waltari, project manager for Sletten Construction.
“All I can say is that the taxpayers will be protected,” said David Burbach, project engineer with Burbach Aquatics.
He added that the contractor will absorb the cost.
Right now, Burbach Aquatics engineers are developing a flushing system that they hope will flush out the problematic material. The voids will then be filled.
“In my professional opinion, we can correct it,” Burbach said.
Burbach said the flushing system is in the hypothetical stage right now and will be tested before being applied to the site.
“We're trying to confirm my hypothesis,” he said.
The testing will take place this week, and if it works as planned, the Powell City Council will be invited to witness a display of the test at the site next week.
The problem was discovered in mid-February when a Burbach Aquatics engineer was looking at a photograph of the site and noticed that the soil didn't look quite right. The material was tested and the levels of fine soil in the aggregate were at 4 percent — double the 2 percent that specifications allow.
Further composite test results of samples from around the site revealed the fine-material level in aggregate is 5.3 percent.
“It's even worse than anyone thought,” Logan said.
Logan said it is not a problem with native soil at the site, but aggregate that was brought in.
The aggregate material was tested and approved last fall.
“There must have been a flaw in the testing procedure,” Burbach said.
Waltari said additional tests will be run on any future material that is brought into the site.
Burbach said he anticipates the aggregate problem will delay the projected January 2010 opening of the $9.5 million facility. He said it may open in March instead, but everyone involved in the project values quality more than a rushed schedule. Waltari said the schedule hasn't been closely evaluated yet.
“The entire team is much more concerned that year zero goes correctly so that the city can have a pleasant experience for years one to 50,” Burbach said.