Client: Barhale Plc for Affinity Water

Location: Roydon, UK

Project Value: €2.0m

Description: Water Treatment Works Upgrade

This upgrade contract consisted of the construction of a new rapid gravity filter structure and associated ancillary plant to provide improved treatment of potable water. The new works which has a capacity of 11,500m3/day enables the plant to address the issues of water quality as well as increasing the overall capacity of the works.

Ward & Burke were responsible for the operation and maintenance of the new water treatment works for a 12 month period.

Main Contract Elements

  • Construction of a new four-cell rapid gravity filter structure with air scour and backwash facilities
  • New steel frame and clad plant building, housing a new MCC, air scour blowers, polyelectrolyte dosing plant, instrument monitoring room and customer protection panel
  • Utilised in house tunnelling capability with the construction of a small shaft, using open cut excavation method.
  • Clean backwash tank and pumping system providing filter backwashing function
  • New lamella plant for treatment of the filter backwash water
  • New supernatant storage tank and return pumping arrangements
  • Upgrades to the existing dirty backwash tanks to support the new process streams
  • Upgrades to the existing contact tank to provide increased chlorination contact retention time for the treated water
  • Replacement of the existing high lift pumps
  • Upgrades to the site security and access arrangements
  • Gravity cascade aerator
  • Automation package for the new areas of plant and interface with the existing instrumentation equipment
  • Electrical installation package for the new areas of plant
  • Polyelectrolyte preparation plant
  • Polyelectrolyte dosing plant
  • New sodium hypochlorite dosing unit for pre oxidiation
  • Replacement of some existing water quality instrumentation

The incoming levels of manganese average 0.045mg/l and the new plant removes it down to less than 0.02 mg/l. Similarly with the iron, the new plant removes the levels from 1.2 mg/l down to less than 0.02 mg/l, Final turbidity is also reduced down to less than 0.2 NTU.

The new filtration plant ties into existing plant and re-uses modified existing plant under this contract to achieve these standards. Sophisticated controls were also installed to ensure fully automatic running of the new and existing plant. Daily plant throughput is 11.5MLD. The Plant was constructed and commissioned within 6 months.

The Contract required the design and construction of a media filtration plant to specifically remove Iron and Manganese from the raw water extracted from 2 boreholes.

The old plant comprised biological filters which were not able to remove the iron and manganese down to acceptable limits. Primarily the manganese was of sufficient presence in the treated water that it was precipitating out in the networks, coating the mains and causing general maintenance problems.