As part of the San Jacinto River Authority (SJRA) Groundwater Reduction Program, a new transmission pipeline was installed from the new surface water plant at Lake Conroe to the existing plants throughout The Woodlands. The Woodlands Division required connections to six existing prestressed concrete tanks located on five different plant sites.
In order to meet Texas Commission on Environment Quality (TCEQ) standards, the new dedicated surface water lines required Air Gaps designed to prevent any backflow. In order to create the air break, the new pipelines, which varied from 12” to 20” in size, needed custom connections to each tank.
The work involved anchoring to the sidewall of a prestressed concrete tank and penetrating through the free-spanning concrete dome. Due to the specialty nature of the work, DN Tanks Concrete Tank Services (CTS) was contracted to design and install the proposed tank modifications. DN Tanks’ experience and expertise in watertight penetrations and structural connections to existing concrete tanks provided SJRA with a single source responsibility for design and construction.
The new pipelines approached each tank and turned vertical just outside the tank’s sidewall. At that point, the pipe was connected to the tank wall, extended up the wall and above the dome. The pipe then turned toward the center of the tank and penetrated through the dome, terminating at a minimum height of two times the pipe diameter above the high water level, meeting TCEQ requirements.