This tunnel enlargement project for the existing Paulsell Lateral Tunnels 1 and 2 was part of Oakland Irrigation District’s infrastructure maintenance and growth plan. Drill Tech performed the expansion excavation, installed portal walls at the end of each tunnel, and provided access management and maintenance throughout operations. Three existing collapsed ventilation shafts were excavated, cleaned out, and backfilled with lean mix. Acting as the General Contractor, Drill Tech also set up check dams and a diversion system to pump leakage/runoff water around the canal/tunnel work, as it was imperative the low-point tunnels were kept dry and available for work.

Drill Tech performed SWPPP management and maintenance, and remained in compliance to other environmental regulations that required work to halt during rainy or foggy weather. Since the project’s time frame was subjected to a schedule-controlled shutdown, Drill Tech mined the two tunnels at once with separate equipment and mucking operations for the most efficient use of time and resources. Fiber-reinforced shotcrete was placed at either 4″ or 6″ thickness through each tunnel to act as the final liner for the future water tunnel.