Hayward Baker has developed customized grout mixes and methodologies tailored to the subsurface conditions and groundwater source to successfully limit infiltration into the LACMTA tunnels.

The project

Since 1988, HBI has performed ground improvement services to reduce the potential for surface and structural settlement as a result of tunneling operations for construction of the Los Angeles subway system. As sections of the system were completed and brought into service, HBI began performing groundwater control grouting on designated tunnel stretches and at subway and light rail stations under multiple maintenance contract agreements to remediate nuisance water infiltration that represents potential safety hazards.

The challenge

Accessing and treating multiple inflow locations within a restricted tunnel environment and tight nightly work window required a highly mobile, streamlined operation with a correspondingly high attention to safety.

The solution

Given the variation in water source, type, and location of the leakage points (through soils or rock), HBI designs and develops customized polyurethane and other chemical grout mixes to treat each location on a case-by-case basis and restore watertight conditions. Repair and restoration of the tunnel lining is accomplished with shotcrete applications. To date, HBI’s grouting expertise, together with a location-specific treatment approach, has resulted in successful completion of three long-term maintenance contracts.

Project Facts

Owner

Los Angeles County Metropolitan Transportation Authority (LACMTA)

Main Contractor(s)

Hayward Baker, Inc.

Keller Business Unit(s)

Hayward Baker

Engineer

Los Angeles County Metropolitan Transportation Authority (LACMTA)