REQUIREMENT

We were asked to specify twin foul water pumps capable of 6l/s at a 12m head due to a two storey basement excavation. The pumps required large solids clearance due to the nature of the multi-occupancy dwelling. A mixer would be needed to prevent the build-up of floating fats and solids. We were asked to plan the route through the two storey basement for the rising main to run.

METHOD

• Twin guide rail mounted pumps were installed with an 80mm solids clearance into a concrete sump 10m long, 2.4m wide and 3.5m deep.
• A horizontal mixer was fitted into the sump in a separate location to operate in conjunction with the pumps, operating just before the pump run.
• A 110mm HDPE rising main was supplied with electrofusion fittings and anti-vibration couplings.

RESULT

• The pumps have an 80mm clear passage through the body of the pump, reducing the chances of blockages.
• The duty / standby set up means each pump is capable of the necessary flow rate, in case one fails for any reason.
• A mixer circulates the water throughout the sump so that floating solids are mixed and pumped away.
• The pumping station service interval has been agreed with the contractor.
• The comprehensive control panel allows for BMS monitoring and a telemetric system for offsite monitoring.

FOCUS ON:

THE BENEFITS OF A MIXER

Installing a mixer in the sump prevents the build up of fat and other floating solids.

Without a mixer, these deposits can build up on the floats and in the upper water column. This can interfere with the float switches operation and degrade the connecting electrical cable.