The Los Angeles County Sanitation District is constructing a 7 mile long, 21.6‐foot diameter tunnel. The tunnel alignment includes many very challenging conditions including: no intermediate shafts, ground conditions ranging from soft ground to rock, two earthquake faults, multiple squeezing ground sections, the potential for encountering explosive gas, over 30 curves, depths of up to 450 feet, and being entirely under groundwater with significant earth and water pressures.
The tunnel machine, at 800 feet in length, is almost as long as 3 football fields, making it the longest operating tunnel machine in the country.
All aspects of the tunneling process are monitored in real‐time using TPC software, which instantly organizes data from both the tunnel machine and ground/utility monitoring points in easy‐to‐read graphical format, and can be used by inspectors to generate daily reports. Automatic alerts are sent to users when parameters are out of range.