Chandler, AZ | Completion: January 2020

This project started out as one thing and ended up another.

The initial project’s goals were to facilitate transmission of 12 MGD from the Gilbert/Mesa joint water treatment plant (Santan) all the way across town to the new Intel facility using mostly existing infrastructure. A transmission line was pieced together and isolated from Zone 1. This transmission line also fed several reservoirs. We knew from the start this was going to be a tricky controls proposition, fraught with potential for catastrophic oscillation issues.

We found the oscillation demons we were expecting during startup, and for the most part mitigated them. Unexpectedly, Intel decided to change their draw from the Santan water to what they had been receiving from Zone 1 (due to water profile issues which were affecting their reverse osmosis units).

Our primary mitigation was to quickly create a spread-spectrum radio network design to coordinate booster pumps at Santan, reservoir fill valves, and distribution valves at Intel. We helped City personnel install a temporary 40-foot-tall base station omnidirectional antenna at one of the booster pump stations, which provided good signal distribution everywhere we needed it.

We saw an opportunity with the new spread-spectrum radio network connecting all the booster stations in Zone 2. We had discussions for several years with the senior Chandler engineers about the utility of having fast station to station communications. Things like pipeline breaks and pump station failures can be quickly and accurately mitigated if adjoining stations were able to talk to each other in real time. Our proposal for the radio network therefore included time to facilitate station coordination. We also used time that would have been used to accomplish system tuning (and flush out the remaining oscillation demons) to develop advanced pump and instrument diagnostics and communications redundancy schema for Zone 2.