An aged bridge along the south shore highway of Molokai was specified for replacement. New abutments required micro-piles to provide the required bearing and seismic design resistance. 40 micro-piles later with a pre-production test and 4 proof tests under their belts, our crews bid Aloha to the Friendly Isle!
Abutments for a replacement bridge on Molokai’s coastal highway were supported on 7e”Ø micro-piles averaging 70 feet deep. Close cooperation and coordination between our crews and the prime contractor assisted in managing, controlling, and minimizing seawater issues at this coastal site.
Project highlights include:
testing of a sacrificial pre-production micro-pile per ASTM D1143 to 220 kips
proof testing in accordance with ASTM D3689
use of multiple drill tooling to address varying site conditions in the subsurface materials
#11 (1d”Ø) Grade 75 epoxy-coated (ASTM A934) threadbar
7e” x .430” OCTG N-80 casing
A field/layer of boulders over 50 feet deep in the specified bond zone posed difficult drilling conditions. We armed our crews with a custom drill bit system consisting of a carbide-tipped ring bit and pilot bit combined with a high-powered down-the-hole (DTH) hammer. All installations extended over 70 feet deep from grade. Additionally, this bridge site along the Molokai coastal highway presented many problems associated with its remoteness and logistics.