SANITARY DISTRICT OF DECATUR WASTEWATER COLLECTION SYSTEM CELLULAR DIGITAL PACKET DATA (CDPD) FEASIBILITY STUDY AND IMPLEMENTATION

The Sanitary District of Decatur, located in central Illinois, serves the communities of Decatur, Forsyth, and Mt. Zion, Illinois. The District's collection system consists of 28 lift stations and four combined sewer overflow (CSO) facilities.The District's existing telemetry infrastructure was experiencing random failures during normal polling cycles resulting from faulty analog dial-up telephone lines. This raised legitimate concerns about network reliability, especially during high flow events. As a result, the District and their Consulting Engineer examined various communications technologies to determine, which would be the most reliable and cost effective method for communication between the plant and the remote sites. Technologies examined included: Standard dial-up telephone lines, leased analog lines, leased digital lines, licensed radio, unlicensed spread spectrum radio, and Cellular Digital Packet Data (CDPD).Cellular Digital Packet Data (CDPD) is an open IP-based standard for transmission of data over the existing analog cellular network. It is an efficient; packet switched digital wireless technology that sends data securely and reliably over dedicated cellular data channels at a rate of up to 19.2 kbps. Charges are based upon the amount of data sent to and from the cell tower plus a small monthly fee to maintain an active IP address.The key benefit of the CDPD Network is that it will allow for more frequent station monitoring without increasing normal operating costs. More frequent polling will provide the District with an opportunity to collect more operational data from each remote site, and view that information in a timely manner. CDPD has proven to be more reliable than the existing dial-up system, with fewer data transmission errors and communication errors. Further, CDPD allows for the reporting of identifiable alarms, and experiences less downtime.