JC Penney - Magnum Piering Projecy of the Month

96 Magnum Helical Piers Installed by Hayward Baker
with No Interruption to Retail Business

Imagine for a minute that you are a geotech contractor assigned to do a large helical pier underpinning project at a JCPenney store – and all the helical piers must be installed on the inside.

Okay, not a big deal – yet.

Now try to imagine having 16” concrete coring systems, high capacity torque motors mounted on forklifts along with portable torque motors with resistance bars, hundreds of feet of hydraulic hoses connected to power packs outside the store, some very low head clearance conditions, helical pier sections being hauled in and staged for installation, bucket after bucket of bag-mixed grout and up to 8 crew members – all working in and around the racks of clothes and the displays in the jewelry and the cosmetic departments.  

Okay, that makes the project a little more interesting and challenging – so just move stuff out of the way until the project is done.  Right?

Wrong.  Now, try to imagine taking on this project with the mandatory condition that there must not be any interruption to normal store business hours during the entire project.

That is exactly the challenge accepted by Hayward Baker Texas and Denver Grouting, a division of Hayward Baker based in Denver, CO.  “This was one of the most demanding underpinning projects we have ever worked on”, said Nathan Parkin, Denver Grouting superintendent.  “Our crew completed this project in two months while working  9:00P.M. to 7:00A.M. shifts each night.  We were required to have the store restored each morning to the exact condition it was in when we began each shift.  That meant photographs and measurements had to be taken at the beginning of each shift, so counters and display racks could be returned to their original position for the next day,” Parkin added.  

Settlement & Underpinning Plan

This store was built on a dried up lake bed.  Approximately one half of the 50,000 sq. ft. building experienced settlement of 6-12 inches in some areas over a period of 10-12 years.  A total of 96 helical piers were specified by engineering to be installed along one exterior wall and around  several of the store’s interior load-bearing columns.  The loads varied from 200 KIPS on the columns to 30 and 40 KIP loads for the walls.  

Project manager Noel Janacek from the Texas division teamed up with project superintendent Nathan Parkin from the Denver office to tackle this extremely challenging helical pier underpinning project.  Magnum round shaft, 3 inch diameter, heavy duty (100 KIP) and standard duty (64 KIP) helical piers were approved by engineering for the project.  Pier section lengths ranging from 3 feet to 6 feet were used on the project due to low head clearance and extremely tight working quarters.  The helical piers were installed to depths ranging from 18 to 24 feet.

In addition, Magnum’s design-build team worked with the project design engineer and Hayward Baker personnel to develop two custom pier caps for anchoring the helical piers to the slab.  All of the core holes in the slab were scored with multiple score rings so the pier caps and the high strength grout could bond to provide the necessary load bearing capacity.  The pier caps were connected to the helical extensions using a bolted connection which eliminated the need for welding.

Once the pier caps were bolted to the helical extension, the crew bucket mixed Portland cement type I & II with pea gravel and grouted the piers and caps.  The grout mix produced 5,000 PSI strength in two hours and 10,000 PSI in 5 days.  All work including cleanup and restoring the floor had to be completed each morning by 7:00A.M.

The Bottom Line – a Successful Project   & a Happy Customer

The project was completed in just shy of two months time.  Shortly thereafter Hayward Baker received a letter from the JCPenney store manager thanking the company and all the personnel on the project for a fantastic job.  He also added an interesting little piece of information about the volume of business the store experienced during the two months.  Instead of volume decreasing, as the manager had expected, store volume actually increased - a little icing on the cake for a job well done.