AWWA CSC91002

This paper describes the experiences of the City of San Marcos (Texas) in contracting for the installation of a Supervisory Control and Data Acquisition (SCADA) system for its water and wastewater utilities from the issuance of contract documents through the time the system is placed in use by the utility operators. Bonds were approved for a utility monitoring system. A microcomputer-driven system was chosen to avoid using the already overloaded minicomputer system. The utility requested bids from prequalified bidders. The requirements for prequalified bidders are listed; of 27 contractors asked to submit bids, only two ultimately did. The system was purchased through a process of sealed proposals rather than competitive bids. Contract negotiations and dealing with the state mandate to accept the lowest and best offering are described. A preconstruction meeting established lines of communication from contractor to utility. Change orders--both their advantages and disadvantages--are discussed. Two change orders were given, which increased the contract cost by 6 percent. Operators were involved in the installation of the SCADA system. Upon commissioning the system, a major glitch was discovered: the RTUs could not communicate with the SCADA computer; this problem required much effort to solve. Lessons learned: even proven systems can have problems in the field, and having the design engineer develop the application software gives the owner a source to diagnose problems and identify the parties responsible for fixing them. The paper concludes with a brief description of the San Marcos SCADA system.