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Bellozanne New Sewerage Treatment Works

Project Details

Hillside Removal and Stabilisation
Contract Award Date September 2016
Contract Completion Date October 2017

Commercial Details

Contract NEC 3 Option B (Design and Build)
Value TBC

Client Details

States of Jersey
Department for Infrastructure
PO Box 412
Beresford House
Bellozanne Road
St Helier

Project Background/Site Description

The existing STW at Bellozanne has been operational for over 50 years and within this period there have been many upgrades which have allowed the STW to continue to treat the islands waste water to a relatively high standard. In recent years the plant has not performed well, has become in efficient and failed to meet required nitrogen standards. It is therefore proposed to replace the existing works with a new facility that will treat the sewerage from a connected population equivalent to 118,000 at the design horizon of 2035.

The land available for the construction of a new STW whilst keeping the existing facility operational is limited. The replacement of the existing works is programmed in phases to ensure continuity of service and is expected to run over a period of 4 to 5 years to a completion in 2022.

The phasing of the construction will require careful sequencing to ensure parts of the new works are completed so that the existing processes can be transferred to the new facility and then decommissioned and demolished for the next construction phase.

The hillside removal and the ongoing site clearance including the removal of the Clinical Waste Incinerator (CWI) and the Household Recycling Centre (HRC) along with old EFW plant area will create space for first phase of the new STW.

In order to create a suitable working area for construction, this particular contract will be to demolish some of the designated buildings and remove some areas of the existing hillside.

Scope of Works

  • Mobilisation and Establishment of Site Compound
  • Traffic management and phasing to meet operational demands of existing facility
  • Site Inductions
  • Installation of security fencing and designated access routes
  • Topographical Survey
  • Identification of Existing Services, Utility Searches and Record Drawings
  • Diversion or relocation of existing services to facilitate permanent works
  • Demolition and disposal of existing structures, site buildings including foundations
  • Install construction platform for screening material from earthworks
  • Create temporary ramp into existing slope face
  • Excavation and removal of site vegetation from existing slope
  • Excavation of existing hillside and cut slope to new profile
  • Excavation to lower the site in the area of the HRC
  • Sorting and grading of excavated material
  • Haulage and disposal of excavated material
  • Breaking and removal of concrete and tarmac hardstand
  • Trimming and preparing surface for new STW
  • Stabilisation of new slope profile
  • Installation of mesh protection netting
  • Diversion of Foul Pipe Pipework
  • Diversion of Storm Pipework
  • Installation of drain at toe of slope
  • Implementation of Site Waste Management Plan