Water-bearing sands being fed from the mountains above the base of the North Shore Mountains were intercepted with the shoring required for the Esplanade Development, "The Pier", which necessitated jet grouting to seal the water prior to excavation.
The initial design consisted of an anchored shotcrete-shoring wall down through 38 feet of glacial tills. A new shoring solution was required when Artesian conditions and flowing sands were discovered, preventing conventional shoring. The difficult ground conditions precluded the option of using face-saving measures.
The joint venture between SWC and Condon-Johnson & Associates, Inc. created an alternative by forming in-situ Jet Grout Columns reinforced with HP Piling as soldier-type piles. Two rows of tieback anchors replaced the four rows originally designed, thus providing cost savings.
This specialized foundation shoring system was able to advance through difficult ground conditions, including artesian pressure coupled with sands and gravels.
Scope of Work
Jet grout columns: ~ 140 each x 2.4’ c/c x 2.6’
Length of wall: 336 LFt
Average depth: 6’ to 24’ below grade
Face area of wall: ~ 8,200 square feet
Soldier piles: 4.8’ c/c
Ground conditions: Tills overlying Artesian conditions including flowing sands