Location:
Western Virginia

Project:
Load Carrying Foundation for a New Pre-Cast Parking Garage

Situation:
Subsurface water, an alluvial cobble layer, and underlying steeply dipping rock karst conditions required micropile installation.  The micropile design loads up to 150 Ton (DL).  Coastal Drilling East (CDE), a division of Shaft Drillers International, was contracted to perform the micropile installation.

The subsurface conditions were far worse than the geotechnical report indicated.  Consequently, the micropile lengths varied greatly from pile to pile. The design complexity of the parking garage combined with the differential settlements and extended micropile lengths required a prompt and decisive response from CDE.

Solution:
In order to meet the required deflection requirements, CDE evaluated each pile and pile caps theoretical deflection as each pile was installed.  The deeper piles were stiffened to meet the stringent deflection criteria.  This alleviated the need for additional micropiles and a redesign of the pile caps and grade beams was avoided.  The innovative solutions provided by CDE kept the project on schedule and on budget.

Results:
All load testing and installation of more than double the original estimated footage of micropiles were completed safely within the original time schedule.