Pumps & Systems, October 2008
An argument in favor of design engineers producing owner's manuals for pumping stations instead of operations and maintenance manuals.
Owner's Manual Versus Operations and Maintenance Manual
Operations and maintenance (O&M) manuals are traditionally provided by engineering consultants when construction is completed on a pumping station, but an O&M manual is not necessarily what a pumping station operator needs. Operators need owner's manuals that resemble what car manufacturers give their customers. They need a manual that describes how to operate the equipment on a daily basis and how the controls work. A pumping station operator needs to know how to turn the pumps on and off, just like a car owner needs to know how to turn the headlights on and off. An operator needs to know what controls automatically turn the pumps on and off, similar to a car owner knowing about the sensor that turns the headlights on at dusk and off at dawn.
O&M manuals prepared by engineering firms are usually a compilation of brochures, cut sheets, pump curves and other information provided by equipment manufacturers. Information is provided about each piece of equipment supplied on the job, but there is little or no explanation of how different pieces of equipment interact. For instance, there may be a cut sheet for a pump control valve and a pump curve for the pump, but there is no discussion about how the pump control valve works when the pump is turned on.
O&M manuals are often ineffective because of how design engineers think. Design engineers focus on providing enough detailed information so that a contractor can build the pumping station. They usually begin by preparing a Piping & Instrument Diagram (P&ID) that identifies major pieces of equipment and explains to instrumentation engineers what controls are needed.
Design engineers then prepare pump data sheets and specifications that show pump vendors exactly what the service point should be on the pump curve and what kind of bearings and seals are needed. Piping designers prepare yard piping drawings and piping sections that give pipe and valve suppliers the information needed to select the correct valves and prepare detailed submittals of the piping components. Electrical engineers prepare one-line diagrams, electrical site plans and electrical specifications for the electrical subcontractor.
During construction, the design engineer collects all sorts of cut sheets and O&M manuals that are submitted for approval by the general contractor. At the end of construction, the design engineer usually looks back in his contract to see if he has done everything and discovers that he owes the owner an O&M manual. The design engineer compiles all of those submittals into a manual that is generally well organized with tabs for each piece of equipment. Any relevant information that the engineer has received during construction is organized in those tabs, but no information relates one piece to another or explains how to use the equipment
At the end of a construction project, the design engineer delivers record (as-built) drawings to the owner. These include the P&IDs, pump plans and elevations, yard piping plans, structural drawings of foundations, architectural plans, ventilation and plumbing drawings and electrical drawings. These documents are often stored at the new pumping station for reference. Unfortunately, operators do not care about how much rebar is in the foundation or about lighting or ventilation ducts. They are not familiar with the jargon used in P&IDs, and piping plans are confusing and useless for an operator. If they turn to the O&M manual for answers, they will find a collection of disconnected pamphlets and brochures.
What Does An Operator Really Need?
Operators need an owner's manual that can be used for training and reference during the life of the pumping station. When a pumping station is brought online, it is a new toy for the operators. They want to know all about it, including what it can do and how it will perform. Later, during continuous operations, new operators with the same questions will be assigned to the station. A reference guide will be needed to help operators remember sequences and operating strategies that may not have been used in a long time. An owner's manual should be kept at the pumping station or in the remote control center where operators often perform daily duties. (Many cities operate multiple pumping stations from a central control center.) The owner's manual can be a printed document, or it can be provided electronically for easy access.
Key Elements of an Owner's Manual
A pumping station owner's manual needs to be divided into several chapters like a car owner's manual:
Design Basis
It is important to explain to operators the design basis for a new pumping station. They need to know the design flow rate, the source of water and some information about the discharge system the pumping station will serve. This information should be presented in laymen's terms.. The owner's manual should be written to the level of an 8th-grade education.
Basic information should be presented about all of the major pieces of equipment on the site. The reasons for having multiple pumps are important for an operator to understand. If variable speed drives are used, the operator needs to know why and when he should use them. If storage tanks are onsite, the operator needs to know how full to keep them and when to empty them. Reasons for auxiliary systems, such as disinfection addition and emergency generators, need to be broadly explained.
Operational Strategies
A chapter should be devoted to explaining operational strategies to the operators. Often pumping stations have more than one source of water supply, such as a surface transmission main and several water wells. The operator needs to know the primary water source and when to supplement it with a secondary source. In some cases, a pumping station can be switched from drawing water from a reservoir to inline pumping. The operator needs to know when to switch and how to do it.
Operating Scenarios
Many pumping stations can be operated in several different modes or strategies. For instance, at different times a pumping station may use different sources of water, such as surface water or well water. Inline pumping may be an option during certain scenarios. In some cases, it may be wise to completely bypass the pumping station during periods of low demand. Each of these scenarios should be explained in detail using at least three visual aids.
One visual aid should be a flow diagram for the system. Figure 1 is an example of a flow diagram. Each operating scenario has a unique set of operating parameters that can be shown in color. The colored diagram shows which valves are open, which pipelines have flow in them and which pumps are operating for the specific scenario. This helps the operators understand how to set valves and pumps to operate in a specific scenario. The scenario illustrated below is "Groundwater Only." This particular pumping station is also capable of operation as "Surface Water Only," "Blended Water," "In-line Pumping" and "Bypass."
(FIGURE 1)
Another set of helpful visual aids are screen shots of the SCADA screens at the control center where the pumps are monitored and controlled. These screen shots are the actual tools the operators use to control the pumps and valves. By studying these pictures the operator can learn what to expect on his computer screen on a regular basis (see Figure 2).
(FIGURE 2)
Sometimes operators have to go to the site of the pumping station and locate equipment. This can happen when there is a maintenance turnaround, when equipment needs to be inspected or if power fails and the pumping station needs to be started manually using emergency generators. In these instances an aerial view of the pumping station is needed. An example is shown in Figure 3.
(FIGURE 3)
Auxiliary Systems
Auxiliary systems should be explained in separate chapters. For instance, disinfection systems should be explained with photographs similar to Figures 4 and 5. Flow diagrams and detailed descriptions of how to operate the equipment are also needed to supplement these pictures.
(FIGURE 4)
(FIGURE 5)
Equipment Operations Sequence (EOS)
This chapter should discuss the operations sequence for each piece of equipment. This includes pumps (constant speed and variable speed), pump control valves, metering stations, chemical feed systems and emergency generators. The operator needs a step-by-step list of how to manually operate each piece of equipment. These functions are often performed by a programmable logic controller (PLC) in the automatic mode; however, if the PLC fails, the pumping station may need to be manually operated.
Further instructions can be included in this chapter to address switching from one operating scenario to another. For instance, switching from pumping out of a storage reservoir to in-line pumping can be a complicated process that needs to be thoroughly explained to the operator.
Equipment Maintenance Schedules
This section provides the recommended general maintenance checks that should be incorporated into the routine maintenance plan. Each piece of equipment must be addressed. Charts are particularly helpful in discussing maintenance schedules (see Table 1 for an example)
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Table 1: Lubricating Grease Requirements |
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NGLI consistency
No. 2
Mobil
Mobilux EP2
Exxon
Unirex N2
Sunoco
Multipurpose EP
SKF
LGMT 2
The chapter on equipment maintenance can also include troubleshooting information as shown in Table 2.
Summary
When a pumping station has been built, the operations and maintenance manuals prepared by design engineers do not usually provide the information needed by plant operators to successfully start-up and operate the pumping station. The operators need an owner's manual geared specifically to meet learning needs. This is not a document normally provided by design engineers under today's project delivery systems but should be offered as an additional service. The owner of the new pumping station should realize the value in having an owner's manual for his operators to use at start-up and for the future. Working together, the design engineer and the owner can make a much smoother transition from construction to operations if an owner's manual is supplied.