Benone Sewerage Scheme

Environmental Engineering


Benone Sewerage Scheme

Project Description

Network Pumping Stations

The function of the outlying pumping stations within the Benone sewerage scheme is to collect and transfer sewage from the existing network to the newly built WwTW at Magilligan for treatment.

In terms of mechanical equipment these stations are conventional like any typical NI Water sewage pumping station only that all of these stations are equipped with pump smart manager intelligent controller within the control panels for accurate monitoring and control.

Magilligan WwTW

The plant serves a tourist resort and there is a wide variation between winter and summer flows to be accommodated both currently and at the design horizon of 2030. The plant is a conventional activated sludge plant with 2 No PSTs, selector tank, 2 No. aeration lanes, and 2 No. FSTs. To deal with the variation of flow and loadings the plant has been designed so that it has the capability to have one stream out of service if required. With the plant fully automated through the intelligent control panels on-site measurements via instrumentation of Turbidity, MLSS and Dissolved Oxygen will be trended to allow for operational changes if and when such conditions occur.

The main feature of this activated sludge plant is the use of the Fine Bubble Diffused Air. The microorganisms in the process require oxygen which is provided by four air blowers arranged duty / standby per aeration lane. The blowers will be variable speed and operate on a basis to maintain the DO set-point thus meaning that the blowers shall only be operating when required to avoid unnecessary operating costs.

With the risk of impact to the bathing water at Magilligan strand and the shellfish waters in Lough Foyle the final effluent discharge from the treatment works is required to have tertiary treatment in the form of Microstrainers along with bacterial reduction with the use of UV disinfection, before the effluent reaches the final effluent pumping station.

The thin sludge tanks will transfer to the thickening plant using the thickener feed pumps the thickening plant consists of 1 off disc thickener. The thickener will thicken the sludges from approximately 0.6% dry solids to the required 6% dry solids content. From here the sludge is pumped to the thick sludge holding tank of 10 days storage capacity. The thickening plant is fully automatic and uses polyelectrolyte made up into liquid form from a bagged powder or liquid brought on site.

Project Statistic:

  • Population Equivalent: 8,696
  • Treatment Flow: 48 l/s

Benone Sewerage Scheme

  • Client: NI Water
  • Completion Date: June 2014
  • Total contract Value: £5.4m