520 West 20th Street
Location:
Manhattan, NY
Client:
Omnibuild Construction Inc.
Contract Value:
$3.6 Million
Project Dates:
July 2017 - November 2019
- Installed foundation and piles
- Installed 36 – 13 3/8” drilled caissons
- Installed 6’x6’ access pits with soldier piles & lagging
- Limited headroom for drilling operations
- Remediation of soils
- Repositioning caisson caps
PROJECT OVERVIEW
A new foundation and piles were necessary to support the addition of five floors to an existing building. Posillico furnished and installed 6’x6’ access pits with soldier piles and lagging for two locations on the east portion of the site. The project also consisted of the installation of 36 drilled caissons to support the additional structure, in variable soil conditions.
WHAT MADE THIS JOB COMPLEX
The compact working conditions in some areas of the site made this job complex. This was especially true during drilling operations as there was limited headroom. Also, there were differing soil conditions throughout the duration of the drilling operations. As the contract documents or soil reports were not indicative of these conditions, our team could not anticipate the complexities of this project. Additionally, the rock quality was low and some column footings were obtrusive with caisson caps. Low rock quality resulted in requiring grouting and re-drilling of rock sockets.
HOW POSILLICO SOLVED IT
Posillico solved the complexities of this project by deploying and using specialized equipment. We also ensured that all workers were trained to safely deal with the hazardous soil conditions. To address the low-quality rock our team grouted and redrilled rock sockets. Furthermore, to solve the column obstructions Posillico manipulated the work sequence & changed the orientation of the caisson caps to clear the existing column footings.
