ROUGH SOILS • The
Juab School Board heard from the architect that the
soil at the site for the new Red Cliff's Elementary
school will be challenging to work with and made
recommendations to the board. The board would like
construction of the new school to start this
summer. We don't know who left the ball, but maybe
it's a good sign
By Myrna Trauntvein
Times-News Correspondent
The site for the Red Cliffs Elementary is difficult to
work with and will require extra effort.
Ross Wentworth, architect, and Chris Houghton and Nick
Slye, with Westland Construction selected as the
construction management firm for the three district building
projects, will be the ones responsible for overseeing the
endeavor.
"The soils at the site are rough," said Wentworth.
He said the site was still being reviewed as to the
best method for dealing with the soil.
"We would like to have the project out on the street
(ready for bidding) by the end of May," he said.
The preparation of a building site is a step-by-step
process that includes analysis of water-table levels and
soil make-up, how utilities are run into the structure,
zoning restrictions, curb-cut location regulations, and
environmental concerns.
Soil Testing looks at two separate things: the
composition of the soil and its ability to support a
structure, and the absorption and drainage rate of the soil
or how well it will accommodate water drainage.
After a soil test has been performed, it is necessary
to have a site-plan design drawn up to indicate placement of
important features.
The slope of the property must also be considered.
"We are leaning toward geopiers," said Wentworth.
Soil compaction methods would not be as good a choice,
said Sly, because the ramming process could break windows in
nearby buildings.
"Geopier is simply a discrete over-excavation and
replacement method that densifies and increases lateral
stress in the surrounding soil," said Wentworth.
Geopiers are installed by drilling a 30-inch
diameter shaft and then ramming crushed stone into the shaft
in 12 inch lifts. So for a 15 foot shaft, you
would have 16 to 18 lifts of rammed aggregate (2 to 3 lifts
in the "bottom bulb" and 14 to 15 in the shaft).
The ramming process takes place with a modified 3,000
to 4,000 lb hydraulic hammer that has a 27 inch beveled
tamper that delivers 300 to 400 blows per minute or 1 to 2
million foot-pounds per minute.
The ramming action pushes and embeds the aggregate
laterally into the sidewalls of the drilled shaft.
High quality and high hardness aggregate is required
for the ramming process or it is
pulverized. Pressuremeter tests have shown that
the Geopier process increases the horizontal stress to near
the passive pressure limit in the upper 3 to 4 diameters of
the pier. Typical spacing is 2 to 3 diameter center to
center under spread footings.
The result is good. One case history for 6-story
parking garage in Sacramento, CA, used 12 to 15 foot Geopier
elements to replace 75 foot drive piles. Total
settlements from the garage are less than 1 inch since the
beginning of construction in 1999.
Another selling point is that they are cost effective
and provide 70 to 120 kips (Kilo Pounds a measure of force)
per pier for the support of shallow spread footings.
"We need to settle this issue so we can move forward,"
said Wentworth.
An accurate plan is required when applying for a
building permit, submitting plans to a zoning review board
and writing specifications for contractors and
subcontractors.
Plans should clearly indicate the intended placement
of the building, municipal sewer connections and municipal
water connections.The site-plan design will show access
roads for construction vehicles as well as the proposed
location of any paved driveway or road.
Curb-cut locations will be indicated as well, and
setbacks from any road to the actual building on the
site&emdash;both of these must adhere to building
regulations.
"We are still working with UDOT on the curbing issue,"
he said.
The site-plan design also has to include the location
of utilities&emdash;where they come in or go out, and if
they are above ground or below.
Grading and site preparation are the first two
important considerations in any building project.
Many of the building steps are performed by
independent crews or subcontractors. For example, the
framing is generally done by one subcontractor specializing
in framing, while the roofing is done by a completely
different subcontractor specializing in roofing. Each
subcontractor is an independent business.
All of the subcontractors will be coordinated by
Westland Construction who will oversee the job and be
responsible for completing the project on time and on
budget.
"We work with the subs," said Houghton.
The board may need to have an extra meeting to approve
some of the upcoming decisions as to the construction of Red
Cliffs Elementary.
"Graduation will be May 24 and that may be a good time
to set a quick meeting," said Delanie Hathaway, board
president. "We could get together before graduation for a
short meeting."
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