Pump station rehabilitation or replacement?

I’ve been working on pump station projects for a long time - almost 20 years. As I’ve seen more and more systems with 30 to 40-year-old (or older) equipment face the problems that come with aging infrastructure - the equipment is at the end of its lifecycle, can’t be repaired or is extremely difficult to repair - and worked on a number of rehabilitation projects, I’ve been thinking about how rehabilitation offers more options than people may first imagine. Plus, a smart rehab can help utilities save a significant amount of money by prolonging the life of the infrastructure and avoiding the cost of a complete replacement and the real estate needed for it.

Rehabilitation doesn’t mean just one-for-one replacement of pumps alone. Rehabilitation can include the integration of new technologies into the existing station, repairs to the structure, upgrades to piping, and more. Bottom line: rehabilitation comes with opportunities for ancillary improvements that can increase the station’s resiliency, efficiency, and life cycle. And it can save money.

For example, Garver is currently working with Central Arkansas Water (CAW) on the rehabilitation of Pump Station No. 12 at the Jackson Reservoir in Little Rock, Arkansas. This raw water pump station needed a lot of ongoing maintenance, and its pumps are below ground, in a vault that also contains the electrical equipment. The rehab, currently under construction, won’t just replace the pumps; it will also relocate all of the electrical equipment. That equipment will be housed in a new above ground building, removing the threat of that equipment being damaged by possible flooding and providing much easier access for operation and maintenance.

Another recent rehabilitation project Garver did with CAW was for their 72 MGD high service pump station (HSPS) No. 1A at the Jack H. Wilson Water Treatment Plant. This project is a good example of how working closely with operational staff can lead to smart solutions for the challenges of continuing operations while rehabbing, as well as an additional example of how ancillary improvements alongside pump replacements can effectively extend the life of the station, and improve its pumping capacity, efficiency, and operational flexibility.

For HSPS 1A, CAW employed a two-phase approach to stagger costs for affordability and to keep the station in operation: we rehabilitated five of HSPS 1A’s 10 pumps, and their associated electrical gear, per phase. While the first five pumps were physically replaced, the second five were still in service, keeping their system operational and keeping customers supplied with water. Collaborating with CAW’s operations staff, the replacements were done during a low demand period from November to April, when the station could get by with five pumps, pumping less.

In addition to the pump replacements, we provided building, structural, ventilation, and electrical rehabilitation throughout HSPS 1A. That included the replacement of the 2.4kV unit distribution center and low voltage panel boards, which improved the safety, reliability, and efficiency of CAW’s operations. In short, rehabilitation can cover a lot of ground.

Of course, there are definite advantages to upgrading to a shiny, completely new replacement pump station. For those who are weighing out which is the best path, rehabilitation or replacement, I’ve put together a short list of questions that can guide consideration.

Replace or rehabilitate? Answering these 10 essential questions will help guide your decision.

1. What is the overall condition of the station?

Assess the pump station holistically, considering the architectural, structural, mechanical, pumping, electrical, and site civil aspects. Are most of these categories in bad condition?

2. Will the existing infrastructure allow for rehabilitation or replacement?

Based on the long-term needs of the station, both could be possible. If the pump station needed more capacity, for example, the existing station could be rehabilitated, and a new expansion could be in the form of an addition to the existing station or a standalone station adjacent to the existing station that is being rehabilitated.

3. Is the current capacity of the station adequate? Does capacity need to be increased due to changes or possible future growth in the water system?

An upgrade in capacity can be done with an existing station rehab as long as the existing pump station has electrical and hydraulic infrastructure capacity to handle the increased pumping.

4. Has there been a change in the distribution system that requires changes to the discharge pressure?

If the station has the electrical and hydraulic availability, then rehab could be an option. But if the hydraulic infrastructure of the station is limited by a maximum pressure and the distribution change requires a higher pressure, then it is likely that a replacement could be warranted.

5. Has the station reached the end of its useful life?

The typical life of the equipment in the pump station is considered to be 25 to 30 years, though some structures may remain in good condition for much longer. After such time, the equipment and electrical gear have become obsolete and are considered outdated technology. If the entire station (back to question number one), including its infrastructure (bones), has reached the end of its useful life then replacement of the station is warranted.

Compare the estimated useful life of a rehabilitated station to the estimated useful life of a replacement station. It may be that the costs of a rehabilitation, even though less than the cost of a replacement station, result in less return on investment because the remaining useful life of the rehabilitated station is less than the projected useful life of the replacement station.

6. Are the existing electrical and controls technology outdated?

If only electrical and controls technology are outdated, or another single component of the station is outdated or in need of replacement, replacement of that technology is warranted and could be part of the overall pump station rehab.

7. What does the existing site footprint allow for?

Is expansion possible? Or a full replacement adjacent to the existing station?

8. Does the current layout of the station allow for ease of access and maintenance?

The existing station may have the infrastructure to handle an upgrade, but it may not have been originally designed for ease of maintenance. Being able to design the station so that it’s easier to operate and maintain equipment is a benefit to having a replacement station.

9. Can the existing station be rehabilitated while maintaining service?

10. What is the cost of constructing a new station compared to the cost of rehabilitation?