Following storm damage after a tornado in northwest Dallas, Texas, certain areas of the Dallas Pistol Club's gun range were deemed unsafe, due to ballistic barriers being destroyed. Remedial work required the installation of new ballistic barriers supported by deep foundations.
There were numerous challenges on the jobsite that led to Chance helical piles being the ideal solution to get the Dallas Pistol Club operating quickly and safely.
The installation site was limited access due to load zoned bridges and existing trees. Also, the time frame allotted for the project was less than a week. Fortunately, helical piles can be installed quickly with a small crew, and unlike concrete, which needs to cure, they could be immediately loaded after installation.
The optimal solution was for the contractor to install Chance RS1275.250 helical piles with two helices, at 18in and 20in, which were installed to an overall length of 30ft. The average installation torque for each pile was 60,000ftlbs. Ultimate compression loads to support the rubber mat barricade was 7 Kips. Due to 10ft or more of the pile terminating above grade, a wind load of 40psf was considered and required the Chance large diameter pipe piles.
Obtaining an accurate soil boring log from a geotechnical report is an important step so engineers can determine the ideal helical pile size and installation depth. A geotechnical investigation was performed on the installation site at Dallas Pistol Club and dense sands were found 8 - 10ft below existing grade. Ten helical piles were installed for the new ballistic barriers and the project was completed in two days.