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Tacoma Micro Tunneling Shaft Bottom Seals Jet Grouting
Location: Port of Tacoma, WA

Project Partner: Frank Coluccio Construction Company (FCC)

Challenge: Provide a watertight bottom seal to four deep excavations to prevent the risk of dewatering moving contaminates from a nearby superfund site. Previously installed CFA columns to support the future pipeline provided an added obstacle to creating a watertight bottom seal.

Overview: Condon-Johnson was contracted by FCC to install jet grout bottom seals in four different sheet pile shored excavations. The plugs were to provide excavation support and ground water control for micro tunneling operations.

Results: Condon-Johnson used a combination of 6 foot and 8 foot diameter columns to complete the work. The jet grout plugs provided the excavation support and ground water control required for the micro tunneling operations. The installed jet grout had unconfined compressive strengths greater than 150-psi at 28 days and a unit weight of 114-pcf. Ground water infiltration through each bottom seal was limited to less than 10-gpm.