Kingsnorth site remediation and enabling works

Concepts

• site preparation
• bromley
• kingsnorth site remediation
• work elements
• ha site
• soil remediation
• work element
• site area
• remediation
• construction site

Location

Medway: Kingsnorth Power Station, Power Station Access Road, Hoo St Werburgh, Rochester ME3 9NQ Easting (x) 580770 Northing (y) 172044

Description

The Works comprises three Work Elements (WE1, WE2, WE3), as described below. Work Element 1 (WE1): Land clearance, soil remediation and bulk excavation and backfilling of a 4.4 ha site to provide a Working Platform. Land clearance shall include removal of vegetation, surface soil bunds and any above or below-ground concrete, brick, obstructions, waste or other structures. The remediation works shall include excavation of known areas of soil contaminated by Heavy Fuel Oil (HFO), removal of the soil by road transport and treatment/ disposal at an appropriately licensed waste management facility, together with verification and validation of remedial excavations and remaining site area. The remaining area (uncontaminated soils) shall be subject to bulk excavation, including the break out and removal of surfacing, below ground obstructions and six large concrete tank bases with cropping of underlying piles. The void space resulting from soil remediation and bulk excavation shall be backfilled to a specified formation level with uncontaminated geotechnically suitable imported material to the required engineering specification to achieve a Working Platform Certificate. Work Element 2 (WE2): Preparation of a 1.6 ha site for a temporary construction laydown area. The works shall comprise land clearance by removal of surface soil bunds, vegetation and any above-ground concrete or other structures to create a level surface, including disposal or waste arisings at an appropriately licensed waste management facility, followed by installation of a geomembrane and placement of a gravel layer above the geomembrane to provide a stable, level ground surface. If found, the works shall include excavation and removal of any unexpected contamination that may be encountered. Work Element 3 (WE3): Preparation of a 1,250 m two-way carriageway length of an access road (on private land). The works shall comprise preparation of an existing access road for use by construction traffic associated with the Works and for future use by construction traffic during redevelopment of the Site, including road widening, bend alignments, surfacing, shoulders, cambers, surface water drainage relocation and connections to existing stormwater system. If found, the works shall include excavation and removal of any unexpected contamination encountered during the works. The Works shall be carried out in accordance with the technical specifications and other requirements, provisions and conditions specified by the Employer in the ITT Documentation.

Total Quantity or Scope

The Works include all design, engineering, procurement, manufacture, supply, site preparation, civil works, construction and/or installation required for site remediation and enabling works to prepare a construction site for a new converter station associated with a planned electricity interconnector between the UK and France. The Works comprise, inter alia: Work Element 1 (WE1): Land clearance, soil remediation and bulk excavation and backfilling (4.4 ha site area):  Removal of ruderal vegetation within the 4.4 ha site area.  Remediation of known areas of soil contaminated by Heavy Fuel Oil (HFO) within the 4.4 ha site area by excavation to a depth of 0.5 m to 1.5 m below ground level, removal of the soil by road transport and treatment/disposal at an appropriately licensed waste management facility. The estimated quantity of contaminated soil is 8,500 m3.  Verification and validation of the removal of all contaminated material from the excavations by sampling of the base and side walls.  Verification and validation of the absence of contaminated material in remaining areas of the 4.4 ha site area by trial pits with sampling at 1 m vertical intervals.  Removal of surface soil bunds and any above or below-ground concrete, brick, obstructions, waste or other structures within the 4.4 ha site area.  Bulk excavation to a depth of 1.4 m below ground level of the remaining areas within the 4.4 ha site area and the break out and removal of surfacing, below ground obstructions and six large concrete tank bases with cropping of the underlying piles.  Backfilling of void space resulting from soil remediation and bulk excavation to ground level, including a 300 mm capping layer, with uncontaminated geotechnically suitable imported material to the required engineering specification to achieve a Working Platform Certificate. The Works also include supplementary site management requirements, including decommissioning of existing boreholes, surface water and groundwater collection, treatment and disposal, and installation of a filter drain network within the 4.4 ha site area. Work Element 2 (WE2): Temporary construction laydown area preparation works (1.6 ha site area):  Land clearance by removal of surface soil bunds, vegetation and any above-ground concrete or other structures within the 1.6 ha site area to create a level surface, including disposal or waste arisings at an appropriately licensed waste management facility.  Installation of a geomembrane within the 1.6 ha site area to prevent migration of any surface contamination caused by future temporary uses into the sub-surface layers, and placement of a 300 mm gravel layer above the geomembrane to provide a stable, level ground surface.  If found, excavation and removal of any unexpected contamination encountered during the works. Work Element 3 (WE3): Access road preparation works (1,250 m two-way carriageway length):  Preparation of the 1,250 m section of the access road for use by construction traffic associated with the Works and for future use by construction traffic during redevelopment of the Site.  Surface repairs and formation repairs to a depth of 300 mm below ground level for approximately 1,000 m road section.  Road widening and bend alignments for approximately 770 m road section and surface area of 1,500 m2.  Construction of one (1 No.) junction from the access road.  If found, excavation and removal of any unexpected contamination encountered during the works. The works include formation, surfacing, shoulders, cambers, surface water drainage relocation and connections to existing stormwater system and other measures required for the safe movement of road vehicles.

CPV Codes

• 45100000 - Site preparation work

Indicators

• Variant bids may be considered.
• This is a one-off contract (no recurrence)
• Renewals are not available.
• Staff qualifications are relevant.

Other Information

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