Tacoma Second Supply Pipeline / Tacoma, WA
Designed and constructed six sets of 30′ diameter receiving shafts for large scale tunneling project. Shafts constructed using a secant pile system in soils ranging from glacial till with glacial outwash, to very soft silty soils, adjacent to the Green River. Shaft depths ranged from 25′ to over 70′. Utilized a casing oscillator as well as a large vertical drill with torque multiplier to allow full depth casing installation. Constructed reinforced slabs at the base of the shafts in underwater conditions.