North MacGregor Storm Sewer Relief Tunnel

OWNER: City of Houston


SOUTHLAND HOLDINGS TEAM: Oscar Renda Contracting Inc.


The tunnel was located beneath the main thoroughfare leading to the main hospitals in downtown Houston on North Macgregor Drive. It consisted of approximately 3,340 ft. of 189” nominal cut diameter and 179” OD x 161-1/4” ID precision made ( zero tolerance) segmented liners. The project had 3- reverse curves. The storm tunnel shaft was located near Brays Bayou.

The contract included single pass tunnel construction, an outfall, and several storm water connections. The tunnel terminated at a location that doubled as a receiving shaft and the location of a 40’x 40’ x 48’ deep junction structure was built around an existing 144” storm drain, that was removed and used for activation of storm tunnel. The tunnel was constructed in predominately mixed face conditions with soft- low plasticity, silty, and sand clays above the tunnel and in the upper portion of the tunnel face. An Earth Pressure Balance Machine, Tunnel Boring Machine (EPBM TBM) was a refurbished Lovat RMP series 185SE-20100. The machine operated only in closed mode to deal with groundwater inflows.  Production of concrete segments was done in-house to meet some of the nation’s toughest tolerances.