Subscribe to our

Groundwater Removal Applications

In some cases, the groundwater is removed so that it does not seep as rapidly into a hole or other excavated area. Groundwater is removed for other reasons-such as for the sake of analysis, safety and environmental reasons and other special situations. Groundwater removal may also be a means to provide a clean water source.

Borehole pumps are often used for groundwater removal in applications that require the pump to fit within a pipe diameter and remove any water that enters that pipe.

In this type of application, the diameter of the hole is a limiting flow factor. The elements of borehole pumps can be staged to develop higher head, as required. The motors in all borehole pumps are cooled by the pumpage. The units can have bottom suction orientations or the motor can be located on the bottom. The clearances are tighter in this design, and several methods are available to limit silt intrusion. Lighter designs suitable for clean potable water applications of composite construction may not be suitable for long-term, more rigorous duties.

Water Management Applications

Ballast in offshore rigs or levels in tailings ponds must be managed to a certain level. Over time, a space fills and water must be transferred to a new location or decanted to achieve process goals. While the solids content is not high, these applications are not considered clean and often see corrosion from the chloride content of saltwater. Ballast is equalized to lend stability to the structure. In tailings ponds and other waste applications, water is removed to create capacity for additional waste.

Dewatering Pump Selection

Depending on the procurement/maintenance philosophy of the owner/operators-as well as the size and pump design chosen for particular applications-the dewatering pumps are considered to be either disposable or rebuildable.

The discharge connection is often at the top of the pump to limit the outer diameter of the pump, allowing placement in tighter spaces. The top discharge design also functions as a cooling jacket but care must be exercised to remove solids from that jacket. The accumulation of solids in the cooling jacket, can clog the pump and/or limit heat dissipation. Units with air-filled motors-which depend on being submersed to dissipate heat-cannot be exposed to the atmosphere for long periods, which effectively limits the level to which they can pump, especially under load. More sophisticated dewatering pumps with isolated positive cooling systems can run with dry motors under load.

In dewatering applications, as with most pumping applications, mechanical seals must maintain their integrity against discharge pressure, keep solids out of the motor and withstand the loads from moving around and pumping solids. Seals for slurry service are engineered and constructed differently than clean water seals.

Conclusion

There is a wide variety of pump types, materials of construction (including coatings) and designs available in today's marketplace. When selecting a pump for any application-dewatering or otherwise-it is important to consider the actual operating parameters within the context of Total Life Cycle Costs. Less expensive disposables should be evaluated against application specific units-designed to last for long cycles and then be rebuilt for extended use-can often prove to be the best overall value in the long run.

Jed Pratt is vice president of sales and marketing for WILO EMU USA LLC, 86 Genesis Parkway, Thomasville, GA 31792, 866-476-0323, www.wilo-emu-usa.com. For additional information on life cycle cost considerations, contact WILO EMU USA LLC, the Hydraulic Institute (www.pumps.org) or Pump Systems Matter (PSM) (www.pumpsystemsmatter.org).

Comments (0)

Subscribe to this comment's feed

Name

Email

Website

Title

Comment

smaller | bigger

Subscribe via email (Registered users only)

I have read and agree to the Terms of Usage.

Write the displayed characters

Add Comment