Tunneling Challenges on Houston’s Northeast Transmission Line (Source: Tunnel Business Magazine)

By Michael Liga

Ten years ago, the City of Houston and regional partners began planning an ambitious pipeline project to convey up to 365 million gallons per day of treated drinking water 16.5 miles across the urban landscape. The mostly 108-inch diameter pipeline, dubbed the Northeast Transmission Line (NETL), is an integral part of the overall regional water plan to meet the 2040 demand and meet groundwater use reduction mandates. It originates near Lake Houston where it will receive treated water from the currently under-expansion Northeast Water Purification Plant. From there, it runs generally west to I-45, with various take-points and interconnects along the way.

The project is split into 13 contract segments, and approximately eight of the 16.5 miles of the pipeline (six segments) are installed to date. Lockwood, Andrews, and Newnam, Inc. (LAN), a national planning, engineering and program management firm, serves as the overall project program manager and design engineer on 3 segments. One of the segments designed by LAN – a 1.2-mile segment of 108-inch water line along city easements – required five tunnel crossings: