This project consisted of new tunnel development to operate as part of a creek flood stormwater diversion for the urban region of Morgan Hill, California. In addition to SEM tunnel construction, Drill Tech designed the temporary shoring (8,700 SF of drilled soldier piles with internal bracing, timber and shotcrete lagging) and perimeter sound wall for the portal. 

Proactive coordination, communication, and monitoring were necessary components to the success of Drill Tech’s operations. Construction of the tunnel took place under existing surface streets in the middle of a narrow easement for the tunnel alignment as granted by the City. These critical areas with low cover (7′ at the shallowest) required monitoring ahead of excavation to establish reliable data records and sequencing plans. Since portions of the tunnel utilized blasting excavation just a few hundred feet from dozens of homes, communicating on blasting times with the client and third parties’ interests were vital to the project. The value engineering that eliminated pre-excavation grouting from the surface street grade to within the tunnel minimized project impacts to local residents.