A 12 MGD municipal water treatment plant, and the first project in the program where a control loop is also a number a regulator can audit against a signed operating permit.
The project brief: a conventional-filtration plant taking raw water through coagulation/flocculation, sedimentation, six gravity filters, and chlorine disinfection with clearwell contact time before high-service pumping to distribution. The automation system spans a redundant hot-standby PLC pair at the main plant, six filter remote I/O panels on a fiber ring, roughly 720 I/O points and 95 field instruments, and two loops — chemical dosing and disinfection CT — that carry real regulatory weight, not just process-quality targets.
This module walks the whole project the way a real water/wastewater automation engineer would: PLC program architecture and redundancy, the full I/O list and instrument index, a worked coagulant feed-rate calculation, a worked clearwell CT calculation tied to the Surface Water Treatment Rule's filtration credit, SCADA screen hierarchy, the six-step filter backwash control narrative, and an ISA-18.2-rationalized alarm matrix. The full worked numbers, complete bill of materials, and finished design reasoning are part of the unlocked module below.