108-inch Northeast Transmission Line, Contract 99C-1 – City of Houston

Houston Texas

As part of a joint venture between the City of Houston and North Harris County Regional Water Authority, LAN designed 6,200 LF of 108-inch waterline with valves and appurtenances, the largest transmission main within the City of Houston. The TWDB-funded project also includes 3,400 LF of 12- and 16-inch waterline and 2,200 LF of roadway reconstruction. These improvements will decrease the City of Houston’s and Harris County’s reliance on groundwater and prevent subsidence. In addition to meeting the projected water demand of the served population, the project also provides a redundant source of water to the George Bush Intercontinental Airport and North Harris County.

A majority of this project is located within limited easement space, where accurate modeling of pipe size, fittings, and appurtenances was required to ensure the infrastructure could be built in the available area. To minimize disruption to the community, one tunnel totaling 165 LF was designed under a 7-lane highway. A temporary road was also constructed to ensure continuous access to private properties throughout construction.

To account for the requirements of the extra-large diameter waterline, LAN worked with the City of Houston to modify the standard specifications and developed standard details for extra-large diameter waterlines, such as pipe embedment requirements, manholes, valves and valve vaults, and manway details.

At a glance

6,200 LF of 108-inch waterline

2,200 LF of roadway reconstruction

165 LF tunnel under a 7-lane highway


Trenchless construction to minimize disruption

Standard detail development for extra-large diameter waterlines

Temporary road construction to provide access


Pipeline Design

Water Supply & Transmission

Trenchless Construction


City of Houston

Related Work

LAN City of San Antonio Soledad Main Street

Transportation Services

trenchless method identification, tunnel shaft design

Water Supply & Transmission