EPB Tunnel Drive of Avenue 45 and Arroyo Drive Relief Sewer, City of Los Angeles

The Avenue 45 and Arroyo Drive Relief Sewer included the construction of approximately 6,400 lineal feet of 115.5-inch diameter tunnel using an Earth Pressure Balance (EPB) Tunnel Boring Machine (TBM). The groundcover over the tunnel ranges from 15 to 55 feet and consists of alluvium that was deposited along the Arroyo Seco, a broad drainage channel which drains from the San Gabriel Mountains, and marine origin bedrock consisting of sandstone, siltstone and claystone. Groundwater over the tunnel ranges from 0 to 40 feet of head. The Geotechnical Baseline Report (GBR) addressed the ground conditions along the project that included size, strength and frequency of boulders within the alluvium. The GBR also addressed characteristics of strengths and compressibility of non-weathered and weathered Puente Formation. This paper details the challenges and conditions found along the alignment during construction and evaluates the parameters presented in the GBR.

Fred Burnett is a Geologist for City of LA with over 25 years experience in geotechnical work including the utilization of trenchless technology. He has experience in exploration during design and has written contract documents related to the subsurface conditions. During construction he reviews submittals and assists the contractor in dealing with ground conditions.