Managing SCADA During a Municipal Water/Wastewater Capital Project

The ISA112 series of SCADA systems standards, currently in development, will provide guidance on how these various facilityowner SCADA design guidelines, templates and examples can be organized into a set of SCADA design standards. A committee of 300 automation professionals are working on the ISA112 standards and Part 1 is on track to be published in late 2024. A draft SCADA Systems Management Lifecycle diagram is downloadable now; excerpts are shown in Figures 2 and 3.

Background stage

Once the design team has been selected, the next step is to conduct a detailed survey of the existing conditions and legacy systems that must be incorporated (or replaced) by the new design. If it is a legacy site, this includes gathering historical documentation about the facility. From a SCADA perspective, this should include, at a minimum, a set of up-to-date piping and instrumentation diagrams (P&IDs), site layouts, floor plans and electrical drawings.

Ideally, electrical drawings will include not only power distribution drawings, but also drawings for programmable logic controller (PLC) panels, controller panels, motor starters, field wiring, input/output (I/O) signals, control system networks and any other control system wiring. Some utilities will even pay a third-party engineering firm to make a set of as-found electrical drawings, P&IDs and floor layouts, so these can be provided to the main project’s design team as part of the background information.

Design brief

Once the design team has a good understanding of the project scope and background information, they will develop a short report that outlines their proposed design solution. This is typically called the “design brief,” which can range from a few pages to more than 100. The design brief usually includes conceptual drawings. Sometimes the design brief is referred to as the “conceptual design phase” or a “10% design."

From a SCADA perspective, the design brief must also include a short section about the proposed automation hardware and how it will work.

Preliminary design

After the design brief has been reviewed by the utility and relevant stakeholders, the next step is to carry out the preliminary design. This stage is often called the “30% design.” There is usually a considerable amount of design effort that must be spent at this stage, as this is when the overall project plan is fully developed and the important question of “Will it all work?” must be sorted out. The preliminary design stage should result in a preliminary design report that outlines the various features of the proposed design and the rationale behind them, and it should be accompanied by a set of preliminary drawings.

Detailed design phases

Once the preliminary design has been reviewed by the utility and feedback has been gathered, the next step is to proceed to detailed design. A commonly used progression of detailed design stages is 50%, 70%, 90% and construction ready. The decision of how many detailed design stages will be used and if supporting technical memos are to be developed will have been defined in the ToR at the start of the project.

At the end of each detailed design stage, an increasingly detailed package of drawings and specifications will be provided to the utility for review. At each design phase, the number of drawings and length of the specifications will increase as well. For example, at 50% design, the specifications section will usually only consist of a table of contents, whereas at 90%, it is not uncommon for a specifications section to consist of hundreds, if not thousands, of pages organized into numbered sections.

The SCADA team’s role during detailed design

From a SCADA perspective, the main goal during detailed design is to ensure that all the various aspects of the design have been properly coordinated with each other, and that the utility’s SCADA design standards are being followed. The overall process systems, and the SCADA system that controls and monitors them, will only be able to function effectively if all the various aspects of the design have been well designed, coordinated and sized properly for all operating modes.

Operating modes include startup, shutdown, online, offline, normal operation and abnormal situations. Thus, both the utility’s and the design team’s SCADA staff need to be able to review all the drawings and specs together, not just the SCADA-specific sections, so they can check the overall design coordination.