How to Choose the Right Construction Dewatering Pump for Your Job Site

Spring construction in Calgary often comes with water.

Snowmelt, groundwater, rain and excavation can quickly create conditions that slow work, damage materials and make access difficult. When water starts collecting, the first instinct can be simple: get a pump.

But not every dewatering pump is right for every job.

A pump that works well for relatively clean water in a shallow excavation may be a poor choice for water filled with sand, gravel or construction debris. Likewise, a pump capable of moving a large volume of water may still underperform if it needs to push that water a significant vertical distance.

Before choosing a construction dewatering pump, start with the site.

1. How Much Water Are You Moving?

Flow rate is one of the first considerations.

How quickly is water entering the excavation or work area? Is it a small, steady amount of groundwater, or are you trying to remove a large accumulation after heavy rainfall?

The pump needs enough capacity to remove water faster than it is entering the area.

Bigger, however, is not automatically better.

Oversizing equipment without considering the rest of the system can create unnecessary cycling, poor operating conditions and additional cost. Pump selection should be based on the actual application rather than simply choosing the largest unit available.

2. How High Does the Water Need to Travel?

The vertical distance a pump must lift water matters.

Moving water across a relatively level site is very different from pumping it from the bottom of a deep excavation to a discharge point at grade.

This is commonly discussed in terms of head.

The greater the required head, the less flow a given pump will typically produce. That means the advertised maximum flow of a pump does not necessarily represent what it will deliver on your job site.

You need to consider both:

How much water needs to move?

and

How hard does the pump have to work to move it there?

3. How Far Away Is the Discharge Point?

Distance matters too.

Every metre of hose or piping creates resistance to flow. Bends, fittings, valves and changes in pipe size add additional losses.

A pump that performs well with a short discharge hose may produce considerably different results when water needs to travel hundreds of feet across a construction site.

Before selecting equipment, map the discharge route.

Consider:

• Vertical lift

• Total hose or pipe length

• Number of bends and fittings

• Pipe or hose diameter

• Discharge elevation

• Required flow at the final discharge point

This gives you a much better picture of what the pump actually needs to accomplish.

4. What Is in the Water?

This is one of the biggest differences between everyday water transfer and construction dewatering.

Job site water is rarely perfectly clean.

It may contain:

• Sand

• Silt

• Mud

• Gravel

• Concrete residue

• Organic material

• Construction debris

The pump needs to be suitable for the material it is expected to handle.

A pump designed primarily for clean water may clog or wear quickly in a dirty excavation. Applications with suspended solids may require equipment designed with greater solids-handling capability.

Before selecting the pump, look at the water, not just the water level.

5. What Power Is Available?

A job site may have very different power limitations depending on the stage of construction.

Before equipment arrives, determine what is actually available.

Questions may include:

• Is electrical service available at the pump location?

• What voltage is available?

• Is three-phase power available?

• Will temporary power be required?

• How far is the pump from the power source?

• Does the site require a portable pumping solution?

The right pump mechanically is not very useful if the job site cannot reliably power it.

6. Can the Pump Handle Changing Conditions?

Construction sites change.

An excavation that contains relatively clean water today may contain considerably more sediment after another stage of work. A discharge location may move. Groundwater may increase. A second excavation may open.

When selecting a dewatering setup, consider what the next few weeks of the project look like, not only today's conditions.

That can help avoid repeatedly changing equipment as the job progresses.

7. What Happens if the Pump Stops?

This question is especially important when water can rise quickly.

If a single pump fails overnight, what happens by morning?

For critical dewatering applications, redundancy may need to be part of the plan. That could mean a standby pump, high-water alarm, automatic controls or another backup strategy appropriate for the site.

The more serious the consequence of pump failure, the more important backup planning becomes.

Correct Construction Dewatering Pump Selection Starts With the Application

Choosing a construction dewatering pump is not just a horsepower decision.

Flow, head, solids, discharge distance, available power and operating conditions all affect performance.

A little planning before the pump is installed can mean better water control, fewer interruptions and less time troubleshooting equipment that was never suited to the application in the first place.

Academy Pump & Motor provides pump sales, service and repair in Calgary and surrounding areas, supporting construction, commercial and industrial applications.

Need help selecting or servicing a pump for your next project?

Call Academy Pump & Motor at 403-437-7888 or visit academypump.ca.