Harbor Point

Scope of Work

To drill and blast approximately 30,000 cubic yards of rock for the construction of a new underground parking garage.

Challenges

The excavation limit was 20 feet from the edge of MNR tracks and went around three sides of UI's transmission lines. The cut from top of ground averaged 45 feet and was a combination of earth and rock. Soldier piles and lagging was installed along the property line prior to excavation. Once the soldier piles were completed, the overburden on top of the ledge was removed. Ledge needed to be removed within 5 feet of the soldier piles. Line drilling was performed at the rock excavation limit prior to blasting within 25 feet of the soldier piles. The line drilling prevented back break from undermining the soldier piles and reduced the vibration limits at MNR and UI facilities. Two geotechnical companies were on site to inspect the blasting activities and monitor the soldier pile wall and surrounding facilities. Six seismographs were used to monitor all blasting vibration. In addition to seismographs, prisms were installed on all the soldier piles and monitored after every blast for deflection. The blasting schedule was regulated by a flagger from MNR. A temporary hold was placed on the tracks for the actual blast. All holds on the tracks and blast times were coordinated between the flagger and MD's foreman.

Outcome

To drill and blast 30,000 yards of rock in downtown Stamford poses its own challenges. Add the challenge of deep cuts abutting a major rail line as well as electric transmission towers, and you have a challenge with no room for error. Through careful planning and communication, the blasting crew was able to successfully complete their scope of work without incident and ahead of schedule.

Customer Comment

Excellent job, very professional. Job well done, guys. I expected two months of drilling and you got it done in 31 days. Well appreciated."

Steve Holmes, Senior Superintendent