A Tale of Two Projects - Helical Pier World

     ^{A Tale of Two Projects}

A comparison of a drilled shaft project and a helical pier project

It is the slower and more complicated of times. It is the faster and easier of times.

In Fort Collins, Colorado, two construction projects are currently underway.  Each project will result in combination 3 or 4 story retail/residential structures.  The projects were started nearly simultaneously, and they are situated only about three football fields apart from one another - close enough to stand at one site and see the equipment on the other site.  Judging from the size of the footprints at each site, the structures will be similar in size, and the approved plans indicate they will have similar structure loads.  So what makes these two projects different?  Well, the deep foundation solution for the first project is drilled shafts, while the deep foundation solution chosen for second project is helical piers.

The 1^st project (let’s call it “The Shaft Project”) is a typical drilled shaft project.  The jobsite is characterized by many pieces of equipment including a large drill rig, a concrete pump, an excavator, a large dump truck, large numbers of laborers, literally tons of rebar, and even more laborers assembling rebar cages.  There are typically a slew of things happening all at once. The drill rig is auguring 24” & 36” diameter, 20’ deep shafts.  Did I mention there is ground water at around 10 feet?  Yes, that means these shafts need to be cased.  Once the drill rig moves on to the next shaft, an excavator moves in with a dump truck and the drill spoils are removed from the site.  Because of the ground water, the shaft needs to be dewatered before the concrete can be poured.  The dump truck leaves, and the excavator is used to lower the rebar cage into the shaft.  Forms are then placed above the shaft with the anchor bolts in position and everything is made ready for the concrete.  The concrete pump and ready mix truck now roll into place, and the shaft is filled with concrete. 

Each shaft was taking about one hour to drill, another hour for spoil removal and rebar cage placement, another hour for form & anchor bolt placement, another half hour for concrete - oh, and then five days for curing.  When I asked the foreman how long it would take until the foundations were complete, he said, “We’re hoping for three weeks".


The 2^nd project (let’s call it “The Already Done Project”) on the other hand is a typical helical pier project.  This jobsite is characterized by only two pieces of equipment - twin excavators, considerably fewer laborers, and the helical piers awaiting installation.  In the 30 minutes I was on site, five piers were installed.  Next, a team of three men were using a laser level to determine final elevation before torching the tops of the piers off and welding on the pier caps. 

When I asked the site foreman how long it would take to complete the deep foundations for this project, his response was, “We’ll be done in a week.”

Two projects of similar size and shape.  That is where the similarities end however.  Aside from being faster and easier, the helical pier foundation project was likely cheaper also, although HPW was not able to obtain any cost data.   Luckily the weather was cooperative, and neither project has hampered by inclement weather.  If the projects would have been subjected to pouring rain, snow, or sleet, the helical project would not have skipped a beat.  The drilled shaft project would have slowed dramatically. 

In addition to the obvious advantages of a shorter project timeline and lower labor costs for the deep foundation phase of the project, other less tangible advantages and benefits include:

• Less interest incurring on the unused real estate
• Reduced project insurance
• Potential incentives for early completion
• Reduced traffic control if applicable
• Lower project management costs
• Improved workplace safety

HPW would like to extend a special thanks to Alpine Site Services, the helical pier installation company on Project #2 The Already Finished Project, for allowing me on their jobsite and for answering a few questions.  If you have any questions for Alpine, contact Mike Oliveira.  And in case your wondering, the answer is yes, the foundation phase of this project is Already Finished! 

(To see the next two phases of these projects, see Part 2 and Part 3 reports.)