To select a submersible pump for leachate, work from the flow and head you need, check the motor against the hydraulic power, and read the exclusions closely. A quotation for an ammonia stripping plant inlet specified a 22 kW cast iron submersible pump delivering about 70 m³/h to a head of about 59 m, and left out almost everything needed to hang it in a sump.
The challenge: a pump you cannot easily reach
A submersible leachate pump sits under liquid, so a failure means lifting it out. Leachate is dirty, may contain solids and is corrosive. The pump must lift the leachate a long way to the treatment plant inlet, so the head is high even though the flow is moderate.
The approach: the specification
- Duty: 69.6 m³/h at 59.4 m head.
- Motor: 22 kW, 2,900 rpm, IP68, on a 400 V three-phase supply.
- Materials: cast iron casing and impeller, stainless steel shaft.
- Seal: a tandem, oil-filled seal chamber, with a cooling jacket.
- Sensors: a moisture and thermal switch on a sensor cable.
- Supplied with: 10 m of power cable, the sensor cable and a 100 mm discharge hosetail.
- Weight: about 366 kg each.
The check on size: lifting 19.3 l/s through 59.4 m takes about 11 kW of hydraulic power. The 22 kW motor is about double that, which allows for pump efficiency and operating margin.
Why the exclusions matter
The quotation, for three pumps, did not include installation, connecting pipework or flexible hose, lifting chains or a davit, guide rails, or anything else needed to connect to the plant. For a 366 kg pump, the lifting equipment and guide rails are a significant part of the job. A buyer comparing prices without the exclusions in mind may compare unlike things.
Sized as if leachate were water
The manufacturer’s quote noted that the leachate was assumed to be water with a maximum temperature of 40°C. Leachate is denser and more viscous than clean water, and it can carry solids, so the duty should be confirmed with real data. Delivery was six to eight weeks from the UK plus five to six weeks by sea.
Why it works
The cooling jacket lets the motor run when the liquid level drops, and the tandem seal with an oil chamber and moisture sensor warns of seal wear before water reaches the motor windings. The materials are a standard choice for moderately aggressive liquid.
What to consider for your own project
- Define the head from the whole pipeline, including friction.
- Give the real leachate properties, not only “water”.
- List what is excluded and price it separately.
- Plan the lifting arrangement before ordering.
- Use the sensors, and wire them into the alarm system.
For the discharge side of the same plant, see our post on replacing discontinued leachate pumps.
Leachate management duties for UK operators are set out in the Environment Agency’s landfill operator guidance.
FAQ
What does IP68 mean?
The motor is protected against continuous immersion.
Why a cooling jacket?
It lets the motor shed heat when the liquid level is low.
Does the price include installation?
Not in this quotation.
Can a water-rated pump handle leachate?
Only after checking density, solids and chemistry.