Sumps and Pumps in Lift pits
The fitting of a sump and pump to control ground water ingress into a lift pit is and has been a very common solution to a ‘leaking lift pit’.
The only problem is that the fitting of a sump pump is quite simply not a solution. The fitting of a sump & pump in a lift pit can potentially cause a whole set of problems for the building owner, installer & specifier (the person who suggested fitting the sump pump).
Most lift pit bases are formed from reinforced concrete, these are specifically designed to be able to support a certain load, this load will no doubt be the weight of the lift mechanism and usually the lift shaft itself.
The steel reinforcement inside reinforced concrete needs around a minimum of 50 mm concrete around it to work, this may be more, it all depends on how that lift pit base has been designed to accept the loads placed upon it.
Reinforced floor slabs are NOT designed for someone to come along months or years later to break a hole in it to form a sump! You risk losing the structural integrity of the floor slab & you are exposing the steel reinforcement to constant wetting.
The pump is fitted inside its sump, ground water enters the pit and is pumped out via the sump pump into adjacent mains drainage. The only problem here is that the water you’re pumping out is now potentially contaminated with oil, grease, hydraulic oil etc.
The Environment agency’s General guide to the prevention of pollution (PPG1) unsurprisingly has something to say on this under
Section 3 Legal Framework
“Controlled waters” include all watercourses, lakes, lochs, canals, coastal waters and water contained in
underground strata (or “groundwater”), and it is an offence to pollute such waters – deliberately or accidentally. In
addition, the formal consent of the Agency is required for many discharges to controlled waters, including direct
discharges and discharges to soakaways. Such consents are granted subject to conditions, and are not issued
Still considering fitting a sump & pump? - Exceptions
There are exceptions where you CAN fit a sump and pump system to a lift pit, the main exceptions are designated fire fighting lifts or an evacuation lift.