Drill Tech performed rehabilitation for the Cal Park Tunnel—located between San Rafael and Larkspur—and constructed a multiuse path within the tunnel per the contract awarded by the County of Marin. The 31′ diameter 1100′ long horseshoe shaped railroad tunnel rehabilitation mostly consisted of demolition and replacement of broken tunnel supports in highly fractured rock conditions as well as wet, mixed face conditions with short initial standup time. Additionally, this contract required 160′ of re-mining through a completely collapsed section of tunnel, “cut and cover” operations, and temporary support of existing sink holes that reach to the surface. Construction of the pedestrian pathway had all the elements of building construction (i.e. CMU wall, steel erection, architectural, electrical and mechanical works). 

Many of the logistical challenges required significant planning and coordination, since site access was shared with public right of way (Amtrack and local businesses), and the width and size of access was single lane. The very limited overhead and width access to work made drilling conditions and shoring access difficult. Drill Tech was responsible for managing these operations while maintaining relations with nearby stakeholders.