THORNEGROUP

Earthworks : Recycling : Reclamation : Demolition : Dismantling

THORESBY LAKE PHASE 1

PRE-SUBSIDENCE WORKS

Client: UK COAL Consultant: Black & Veatch

THORNEGROUP

THORESBY LAKE PHASE 1

Project Overview

Earthworks : Recycling : Reclamation : Demolition : Dismantling

Thorne were appointed Principal Contractor for the Thoresby Lake Phase 1 project which was undertaken within the tranquil settings of Thoresby Estate.

The subsidence would lead to the lake bursting its banks and by-passing the man-made dam at the Eastern end.

The Client, UK COAL, intended to open new coal workings beneath the lake which would subsequently be affected by up to 900mm of subsidence.

The aim of the project was to raise and reprofile the Northern and Southern shores of the lake prior to the subsidence occurring.

Located within the historic Thoresby Estate and a Grade 1 listed deer park, the site was under the close scrutiny of the Estate Trustees, English Heritage, English Nature, the Environment Agency & Hotel (located within Thoresby Hall) and was also designated as a SSSI.

Close consultation between the interested parties and sympathetic project management were required to achieve a swift and efficient completion to the works on behalf of the Client.

Enabling Works

South Shore

North Shore

Project Summary

THORNEGROUP

THORESBY LAKE PHASE 1

Earthworks : Recycling : Reclamation : Demolition : Dismantling

Project Overview

The project consisted of 3 elements:

1, Enabling works to allow construction access

2, South shore works – realignment, raising and bank reinforcement

3, North shore works – realignment, raising and natural habitat creation

N

Enabling Works

South Shore

North Shore

Project Summary

THORNEGROUP

THORESBY LAKE PHASE 1

Earthworks : Recycling : Reclamation : Demolition : Dismantling

Site entrance set up & 400m track installed to compound location

South Shore

Project Overview

Enabling Works

North Shore

Project Summary

THORNEGROUP

THORESBY LAKE PHASE 1

Earthworks : Recycling : Reclamation : Demolition : Dismantling

Access to the Northern shore and Lake Outfall 1 installed

South Shore

Project Overview

Enabling Works

North Shore

Project Summary

THORNEGROUP

THORESBY LAKE PHASE 1

Earthworks : Recycling : Reclamation : Demolition : Dismantling

Temporary bridge, including foundations installed for access to the dam

A 24m, 45t rated, construction bridge, requiring a 100t crane for installation

South Shore

Project Overview

Enabling Works

North Shore

Project Summary

THORNEGROUP

THORESBY LAKE PHASE 1

Earthworks : Recycling : Reclamation : Demolition : Dismantling

Access track constructed on the dam

South Shore

Project Overview

Enabling Works

North Shore

Project Summary

THORNEGROUP

THORESBY LAKE PHASE 1

Earthworks : Recycling : Reclamation : Demolition : Dismantling

2nd Temporary bridge installed for access across lake outfall 2

A 13m, 45t rated, construction bridge, requiring a 100t crane for installation

South Shore

Project Overview

Enabling Works

North Shore

Project Summary

THORNEGROUP

THORESBY LAKE PHASE 1

South Shore

Earthworks : Recycling : Reclamation : Demolition : Dismantling

Project Overview

Enabling Works

Access from bridge to South shore working area installed

Safety fencing and site signage installed

North Shore

Project Summary

THORNEGROUP

THORESBY LAKE PHASE 1

South Shore

North Shore

Project Summary

Earthworks : Recycling : Reclamation : Demolition : Dismantling

Project Overview

Enabling Works

South Shore: Site Clearance

Approximately 20 trees professionally felled

Listed Monument removed for renovation

Topsoil stripped prior to realignment

THORNEGROUP

THORESBY LAKE PHASE 1

South Shore

North Shore

Project Summary

Earthworks : Recycling : Reclamation : Demolition : Dismantling

Project Overview

Enabling Works

South Shore: Realignment

Chainage 0 to 160 m

Bank cut to 1:6 gradient

Cut transported to fill area

Erosion protection placed

Topsoil reinstated

THORNEGROUP

THORESBY LAKE PHASE 1

South Shore

North Shore

Project Summary

Earthworks : Recycling : Reclamation : Demolition : Dismantling

Project Overview

Enabling Works

South Shore: Realignment

Chainage 160 to 400 m

New bank alignment cut

Bank cut to 1:2.5 gradient

Cut placed in fill areas and banks raised

Profile for armourstone installation cut

THORNEGROUP

THORESBY LAKE PHASE 1

South Shore

North Shore

Project Summary

Earthworks : Recycling : Reclamation : Demolition : Dismantling

Project Overview

Enabling Works

South Shore: Realignment

Chainage 160 to 400 m

New island and channel formed

Sub-armourstone geotextile installed

Armourstone erosion protection installed

Island topsoil applied

Topsoil reinstated and seeded

Accesses tidied and temporary crossings removed

THORNEGROUP

THORESBY LAKE PHASE 1

South Shore

North Shore

Project Summary

Earthworks : Recycling : Reclamation : Demolition : Dismantling

Project Overview

Enabling Works

North Shore: Site Clearance

~ 100 trees professionally felled

15,000 m2 of vegetation cleared

3,500 m2 of topsoil stripped

Reeds and bulrushes transplanted

THORNEGROUP

THORESBY LAKE PHASE 1

South Shore

North Shore

Project Summary

Earthworks : Recycling : Reclamation : Demolition : Dismantling

Project Overview

Enabling Works

North Shore: Realignment

Colliery shale front line bank removed

Small flooding protection bank left in situ

Lake bed formed behind original bank

New shoreline bund formed

THORNEGROUP

THORESBY LAKE PHASE 1

South Shore

North Shore

Project Summary

Earthworks : Recycling : Reclamation : Demolition : Dismantling

Project Overview

Enabling Works

North Shore: Finishing Works

Natural habitats created

Boat launch excavated and shuttered

Boat launch cast and married-in to bund

Flooding protection bank removed

THORNEGROUP

THORESBY LAKE PHASE 1

South Shore

North Shore

Project Summary

Earthworks : Recycling : Reclamation : Demolition : Dismantling

Project Overview

Enabling Works

Project Summary: The Finished Product

South Shore: Water level raised, pre-subsidence

THORNEGROUP

THORESBY LAKE PHASE 1

South Shore

North Shore

Project Summary

Earthworks : Recycling : Reclamation : Demolition : Dismantling

Project Overview

Enabling Works

Project Summary: The Finished Product

North Shore: Water level raised, post-subsidence

THORNEGROUP

THORESBY LAKE PHASE 1

South Shore

North Shore

Project Summary

Earthworks : Recycling : Reclamation : Demolition : Dismantling

Project Overview

Enabling Works

Project Summary: Analysis

A score of ZERO Heath & Safety incidents recorded

A score of ZERO Environmental incidents recorded

A Considerate Constructors Scheme score of 32.75 achieved

A post-completion Client satisfaction survey score of 98%

Works completed in advance of the of the mining subsidence

Works completed 2 weeks AHEAD of the 17 week programme

Final cost of the works to the Client at 4% UNDER BUDGET