Renovation of a water / sewer project in Texas City, Texas. Completed plans call for the renovation of a water / sewer project.

GCWA is investigating the use of automatic valve closure systems to provide added safety to the chlorine gas system. The Thomas Mackey water treatment plant utilizes (1) ton chlorine gas containers as part of the disinfection process. Automatic valve closure systems are actuators that mount directly onto the cylinder valve stem system. An automatic valve closure system is designed to provide 40 - 50 ft-lb of closing torque to the valve stem upon receipt of an emergency shutdown signal, stopping any leakage that may be occurring. The shutdown system is requested as an additional line of defense to an approved safety plan. It automatically shuts the primary isolation valves on the containers if a detectable gaseous chlorine leak is detected. The actuator mounts on the cylinder valve stem by means of a drive bushing and two parallel rods that straddle the gas valve nozzle making it easy to remove during cylinder changes. The actuator is designed to apply 40 ft-lb of closing torque to the valve stem after receiving an emergency shut down signal from any number of sources such as a chlorine gas detector. The actuator is designed as an emergency closure device and therefore is powered only in the closing direction. At the TMWTP, the actuators shall be installed on each of the one (1) ton chlorine gas cylinders designed for automatic closure of the valve. The actuator shall be tied into the chlorine gas detector installed within the chlorine gas building as well as the Emergency Shutdown Button and plant SCADA. In addition, Plant operators will utilize the actuators to close the valves during change out of the cylinders. Actuators shall be attached to the stem with the appropriate torque specs. The actuators shall be tested when installed on the new cylinders, which ensures that the actuators are operating according to design specification. The chlorine shut-off device protects the plant with associated chlorine system and equipment from accelerated corrosion caused by chlorine gas escape while the installation is unmanned. It also supplements and enhances the protection of operating personnel against exposure to chlorine gas.