Automation of Water Resource Recovery Facilities. Water Environment Federation

      FIGURE 3.1 Typical automation project execution.

1.1 Project Structure

      Regardless of the project structure, early and continuous involvement by utility personnel at all levels of the organization is important. This can be via site interviews or meetings with facility maintenance and operating personnel and the utility’s engineering, information technology, and management staff. Inclusion of information technology staff at an early stage should not to be underestimated because information technology plays a significant role in all automation projects involving networks. This involvement is so critical to the success of any project (including automation types) that it will be reemphasized later in the manual.

      Wastewater treatment projects can be cost-driven, time-driven, or both. A cost-driven project aims to limit budget overruns by enabling the schedule to be adjusted for optimum design efficiency. A time-driven project places more emphasis on deadlines, limiting the engineer’s ability to make any schedule changes. Most municipal wastewater treatment projects are cost-driven, with construction typically implemented via a low bid process. Utilities have more flexibility with the design award process and can use any of the methods described here.

      Wastewater utilities typically use various methods to contract project design including fixed-cost (lump-sum), cost-plus, or design–build fee structures. In the fixed-cost approach, the utility pays an engineering firm a predetermined fee to provide all of the project’s design documents, from the request for proposal (RFP) to final design. In the cost-plus approach, the utility agrees to pay an engineering firm at an hourly rate for clearly defined services. In the design–build approach, the owner either prepares the contract documents (or hires a design engineer to do so) and then hires a project team that consists of an engineering team, subconsultants, a general contractor, and subcontractors to completely design and construct the WRRF. The approach may also be mixed; for example, the utility may pay one engineering firm a flat fee for the design and pay another an hourly rate to oversee construction. Another approach is to use a performance-contracting model that is similar to the design–build mode in which a project is conducted based on proven performance and payback and project risk can be borne by the contractor.

      The desired level of detail can also vary. Fewer details are needed for RFP documents, for example, than those needed for system-integration specifications. For RFP documents, the designer should define criteria for programming the control system’s process controllers (i.e., programmable logic controllers [PLCs], remote terminal units [RTUs], and distributed control system [DCS]) while, for system-integration specifications, the designer should note the actual programming logic (e.g., ladder logic and sequential function charts, etc.) required to implement control strategies.

      Some utilities prequalify control system integrators for their automation projects. Koons and Conley (2004) recommend using a decision matrix to select a system integrator. When creating this matrix, utility staff should assign weights to all decision criteria including

      • Eligibility,

      • Unique features,

      • Project understanding,

      • Hardware and software recommendations,

      • Project approach, and

      • Price.

      The Control System Integrators Association publishes free guides to help engineers and utilities document criteria for selecting system integrators (see the reference section at end of this chapter). Additional factors to consider in selecting system integrators include

      • Field-service capabilities to support the project during startup, commissioning, and after system acceptance;

      • Project management capabilities, including cost-control methods and scheduling; the project manager should have management training and certification credentials from organizations such as The Professional Management Institute (http://www.pmi.org), the American Society for the Advancement of Project Management (http://www.asapm.org), and the International Association of Project and Program Management (http://www.iappm.org);

      • Problem resolution approach and documented record of how problems were addressed, including any pending litigation;

      • Affiliation with a control system equipment manufacturer;

      • Insurance limits and bonding capacity;

      • Project backlog, including other projects being handled concurrently; and

      • Ability to staff project adequately.

      The final selection process is based on consideration of financial, technical, and managerial capabilities. For the wastewater treatment industry, experience with wastewater-related projects should be considered more than industrial project experience.

      Management of an automation or instrumentation and controls (I&C) design project in wastewater facilities follows similar patterns for I&C design projects in other process industries. Jekielek (2003) offers additional guidance on planning I&C design projects.

      As with other engineering or construction projects, automation projects are affected differently by design decisions depending on the various stages of the project. For example, any decisions made at the beginning stage of a project life cycle have far greater influence than those made at later stages, as Figure 3.2 shows.

1.2 Predesign Phase

      The predesign phase has a significant influence on the entire project and the design process itself, especially when the project is time-driven and involves significant subconsultants. The goals of this phase are for all stakeholders to agree on project objectives and the necessary steps to achieve them. Participation of utility engineers, project managers, client information technology staff, and facility operations and maintenance (O&M) staff (e.g., facility supervisors, chief operators, facility electricians, instrumentation and controls technicians, etc.) is critical because these groups will either be using the final product or be responsible for its maintenance.

      During this phase, design team members should be chosen and the method for working together should be determined. Ideally, the design team should include the project manager(s), the owner’s representatives, representatives of all related engineering disciplines, and any significant subconsultants. This team will establish the project’s operation and control philosophies; design standards; and the architectural, civil, electrical, instrumentation, mechanical, and structural memoranda on which the design documents will be based. Automation design must be closely developed with process design because early decisions by the process team ultimately will affect it. This is also a great opportunity for process design to incorporate process dynamic behavior based on modeling, which, in turn, will allow automation design to accommodate this behavior in its design.