Low Headroom Micropile Installation
The University Mound reservoir is located in the middle of San Francisco and stores over 50 million gallons of water for emergency situations. For this project, Malcolm designed and installed 542 micropiles along the inside slope of the reservoir. Drill depths averaged 50 feet, but varied greatly around the reservoir depending on the amount of embankment fill that had to be drilled through. All the micropiles were bonded in either the dense Colma sands or Franciscan bedrock.
One of the key challenges was working in the low headroom conditions, which were at times as low as 8 feet. Installation rates varied, as well as the bar length and coupler configurations depending on the headroom at each location. All the micropiles were located along the 3 to 1 slope of the reservoir, which presented another key challenge since drilling equipment could not install piles at this inclination. To solve this issue, Malcolm fabricated adjustable drill platforms that increased the level work pad at each footing location, enabling machinery and personnel to work safely and efficiently throughout the installation process. Malcolm completed this tight-access drilling project on time and within the budget.
