Designing for a narrow chamber

INTRODUCTION

We were tasked with designing and installing a twin pump surface water pumping station with a pre-existing concrete ring sump. This had been designed and constructed by our client, a civil engineering firm.

The pumping station is one of several which will remove surface and storm water from a residential development in East London. It accepts water from an adjacent attenuation chamber formed from soakaway crates and a geotextile membrane.

So far so standard, however there were several constraints which made the project more challenging.

METHOD

The concrete ring sump is 2,500mm deep and a mere 1,200mm in diameter.

The inlet’s invert is 2,000mm deep and the base of the sump is at 2,500mm. With only 500mm between invert and base of the chamber there isn’t enough volume for a standard float system to function well.

Additionally, the narrowness of the sump could result in floats becoming tangled or obstructed by each other, the pump equipment or the pipes and rails.

To avoid this risk, we installed a pressure pole switch which can control both pumps and provide high level alarm functions. As well as being compact and robust, it is much more precise than a system of floats. For this installation, where the levels are all set within 500mm, this precision will mean the pumping station will operate predictably and reliably.

The confined nature of the sump would also make installing the pump sets and equipment more challenging for our pump engineers.

We specified powerful and reliable Ama Porter 600 pumps with pedestals. These discharge to DN65 galvanised steel before combining into an electrofusion welded manifold. This in turn connects via a pre-installed DN100 low pressure soil pipe to the main sewer.

As a backup we also installed two standard double action floats. These provide start / stop and high-level alarm functions in the unlikely event that the pressure pole switch fails.

We installed the station’s control panel in the plant room of a nearby building.

RESOLUTION

Our project manager specified a pumping station which will operate reliably within the tight constraints presented by the design of the sump.

The pressure pole switch allows precise control of the pump set over a short operating range, whilst avoiding the risk of floats becoming tangled.

Our skilled engineers, who are all trained in confined entry, were able to install and commission the equipment in the very narrow chamber.

There are several similar surface water pumping stations at the same development. We will be installing pump sets in each of these.

The sump is very narrow.

During installation, showing the pressure pole next to the ladder.

The commissioned pumping station.

The pressure pole switch.

 

FOCUS ON

Pressure pole pump switches

Pressure pole switches combine very precise operation with a compact and robust form. They are very reliable.

They are supplied with three factory set level switches – Pump 1 On/Off, Pump 2 On/Off, High Level Alarm.

Call 01442 211554 or email sales@edincare.com for advice on the best level controls and control equipment for your project.