In package pumping systems, everyone wants and needs something different. The reality is that every site is vastly different and, in most cases, so are the pumping requirements. Hundreds of questions and preferences apply to each new or replacement system. The concept that we can simply buy a 6-feet inner diameter (ID) by 20-feet deep sump with two each 5-horsepower (hp) submersible pumps that alternate—and make it work on-site on any site for any owner—is inaccurate.
Each site has its own constraints, and each owner has their preferred or required design configuration. Meeting those individual requirements with designs that include all structural, mechanical, electrical, control and communications for each specific site and owner remains the challenge of package system design, supply and construction.
There are four major water types that drive the design of most package pumping systems. Wastewater (sewer), stormwater (water that is on or has touched the ground), industrial process water (various configurations, temperature and potential of hydrogen [pH]) and clean water along with potable/drinking water. Each of these water types includes thousands of potential structural, mechanical, electrical and control and communication configurations. Each has its own typical owner, and each has a long list of design fundamentals that must be adhered to. The following are some of the major issues and choices that drive individual package system design for these four major water types.
1. Sewer Pumping Systems
Americans are particular about the security and conveyance of sewer water, from its source to treatment. In a perfect world, every home or business would be built on the same hill with the sewer plant at the bottom. All sewer water would then flow via gravity to the treatment plant. Unfortunately, a great deal of geography—including both hills and valleys, as well as areas of flat terrain—eliminate this perfect world scenario, and thus pumping systems are required. Municipal pumping systems are typically managed by the local government, and as particular as individuals can be, municipalities also maintain their own set of standards for these systems.
Submersible pumping system
This design features submersible pumps (two or more) installed at the bottom of the sump. These systems lift the water up and then typically turn horizontal (4 feet to 6 feet below grade) before moving through various operational or mechanical components (i.e., valves and piping). Next, the mechanical piping is combined into a single force main that carries the water via the pump to a point where the water ultimately discharges due to gravity.
Above-grade (suction type) pumping systems
In this type of sewer pumping system, two or more pumps are found on the surface. They are typically configured on a mechanical skid that also includes the operational valves. The water is essentially sucked up to the surface and then conveyed via force back underground to the force main, which then carries it to a point where it discharges to gravity. This process, like the submersible, is repeated again and again with pumping systems until the water reaches the treatment plant.
Wet/dry pumping systems
The last of the three major sewer pumping system types features two adjacent sumps. One sump contains the sewer water arriving either by gravity or by force. The other sump contains all of the mechanical and sometimes some or all of the electrical. These wet/dry systems are the most expensive and require the most engineering and design considerations, as they are typically designed for regular below-ground (confined space) access by operation and maintenance personnel.
These three types of sewer pumping systems have their respective costs and technical advantages and disadvantages. Suffice it to say that when the owner decides which type of pump system they want, the package design
company is compelled to follow their design preferences.
2. Stormwater Pumping Systems
Stormwater pumping is becoming the most common and, in some cases, the most complex of the four major water types. Due to newly enacted laws in many states, development on previously untouched raw land requires developers to collect and treat the stormwater prior to its release. The concept is based on treating stormwater pollution at the site of its creation.
For example, if you were to build a new warehouse store on undeveloped raw land, that development would require stormwater treatment on the store site. To save space, treatment could be done under the parking lot, where the hydrocarbons and the solids (e.g., asbestos) would be separated out of the stormwater falling on the building and its parking lot. Once treated, the water would then be clean enough to discharge into the new or existing stormwater conveyance system. The reality of stormwater treatment, on the many new sites that could be creating stormwater pollution, is that lots of pumping to and from stormwater treatment is also required. This pumping and the related local requirements relative to maximum discharge rates create significant and often complex operational parameters for the stormwater pumping systems required.
3. Industrial Process Water
This wide and complex water type ranges from both high and low water temperature to high and low pH. The
water involved may be toxic and may contain many chemicals and challenges in both liquid and solid forms. Industrial process water pumping may occur on the factory floor with either buried or above-grade sumps.
The sumps are often made of materials best suited for the water type, such as concrete, fiberglass, stainless steel, etc. These sumps are often required to have double walls that allow for leak detection and related alarm notification. In other words, this type of water may involve a high volume of heavy solids that may require various forms of maceration and/or separation prior to pumping.
Industrial water pumping may just involve a large amount of water and pumping systems that fit into that
facility and comply with that company’s existing control and communication network. In many cases, the key to
meeting the requirements of a specific industry is the package designer’s experience with many different control and communication requirements that could be required for any new pumping system on an existing system, such as a petrol chemical refinery.
Industrial process pumping involves meeting the needs and requirements of the owner’s engineering firm. In virtually all cases, the pumping system designer or packager must be able to meet the design, documentation, specification and on-site requirements of that specific company in its particular industry.
4. Booster Pumping Systems
This is in many ways the most complex and challenging of all water types. It also is often the most complex and challenging type of system to design. First, in most clean water booster pumping systems, starting and stopping is not based on level, but rather is based on pressure. An additional complexity can be the requirement to have a separate but related pumping system for fire flow in the same building that houses the domestic flows with their own respective mechanical, electrical, control and communication aspects. All custom/design-specific
potable water booster pumping systems require a higher level of experience and a broader range of project scope for the designer or packager.
Despite popular belief, virtually all major clean water booster systems begin with the design and layout within the building, which will contain all structural, mechanical and electrical—as well as the control and communication—aspects of both the domestic flow and the fire flow pumping systems. These requirements begin with the plan view drawings within and around the building. It is important to remember that everything that goes into the building will someday have to come out. Maintenance personnel must be able to navigate and access these systems as necessary for years to come.
Water booster stations and their related equipment layout, along with the required access and serviceability of the entire system, is a matter that cannot be dealt with lightly. This type of system often operates at significant levels of pounds per square inch (psi) with major demands on all structural, mechanical and electrical. In short, it can be a sophisticated and significant system that is expected to operate automatically and without issues
in both domestic and fire flow scenarios
24 hours a day.
On-Site Technicians
The custom package pumping system world is ultimately anchored with on-site technicians, all of whom must be experienced and capable of starting, testing and training all involved in the long-term operation of the water type that particular system is intended for. No design and supply company can be without them. Ultimately, the ability to start up, test, prove and train all parties in all aspects of the system design and its operation comes down to that company’s on-site capability.
The old way, involving a civil engineer with some mechanical and electrical support designing and specifying a system to be site built (within budget) by a third-party contractor, has been challenged by the complete custom package companies who can design, supply, start up, test, train and document every aspect of every custom system. These companies are engaged in a great deal of projects per year, and they have the experience and capability to meet the demands of even the most particular owner/operator.
“The future is now” regarding electrical design and supervisory control and data acquisition (SCADA) design. No longer can any pumping system design push these two aspects into the third-party realm. Instead, the system design, in many ways, now begins with the electrical and control/communication (SCADA) requirements. The days of driving out to the pumping system to see what’s wrong have been replaced by true, two-way SCADA. In other words, systems that can self-diagnose problems, send alerts and then remotely change and/or correct what is wrong are in demand.
Today, most owner or operator of multiple systems wants the efficiency
of two-way SCADA. The system design relative to the various control aspects of
the pumps—such as level sensing, flow rates, start and stop points and electrical control of aspects ranging from variable frequency drives (VFDs) to level sensing and from psi to pumping rates—becomes the basis of the overall system design and its remote control.
Finally, total pumping system designers are and must be responsible for the pumping system layout on the site. Whether the job involves the replacement of an existing system or the design and configuration of a completely new system, it is a lot about the physical layout of the system and the related convenience of utilities as well as security access and egress.
To be specific, driveways, fencing, general security, convenience, water and power can affect the design. For these reasons and other aspects of site design, the layout of the overall system becomes either a golden example of the way it should be or just another example of not being attentive to details. Pumping system problems typically come at night, in the rain or snow or on national holidays and weekends. Therefore, when maintenance personnel must go to
the site to resolve an issue, system
designers need to make it possible for them to do so with good lighting and comfortable access to all power.
It is not uncommon to develop site plans that include control buildings, chemical feed systems, generators, retaining and/or security walls and fences. Many owners are knowledgeable, and much like the common practice in septic drain fields, they now require enough land for today’s system and the replacement system that will be required in the next 50 to 75 years.
The world of package pumping system design is not for the faint of heart. The design, supply and construction of these utilities in wastewater, stormwater, industrial process and clean water is here to stay.
Today, the best civil, mechanical, structural, electrical and control and communications engineers are in the package pumping system design world. They are working to manage one of the world’s finite resources, water, while also monitoring power consumption and maximizing control capability from anywhere.