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Gordon Wilson Construction Director

Sighthill TRA Contract 1

Brownfield Land Scotland 2019

Sighthill TRA Contract 1

• The Circular Economy • A circular economy is an alternative to a traditional linear economy

(make, use, dispose) in which we keep resources in use for as long as possible, extract the maximum value from them whilst in use, then recover and regenerate products and materials at the end of each service life.

(Not a concept we had in late 1800’s and early 1900’s)

Sighthill TRA Contract 1

• Zero Waste Plan – we cant influence how they were produced but we can influence how they are reused

• Safeguarding Scotland’s Resources- maximising reuse and upgrading materials replaces the need for the use of natural resources

• Making Things Last – not necessarily in its current form. Processing to renew or revive material or finding a new use.

Sighthill TRA Contract 1

• Client - Glasgow City Council

• Main Contractor – VHE

• Designer – WYG

• Project Manager - Gardener and Theobald

• Client Technical Advisor - SWECO

Sighthill TRA Contract 1

Sighthill TRA Contract 1 • Site history and key features

1947 2016 Future

Sighthill TRA Contract 1

2015

1960

Numerous changes and reuses over the years

1970

NEC 3 Design and Construct WYG acting as designer for VHE Longstanding relationship with VHE both D&C and traditional Experience of Galligu in NW England

9

• Site Clearance • Remediation of identified hotspots outside of

Galligu area • Galligu Containment - Slurry Wall around

main Galligu area • Galligu Containment – Geosynthetic Clay Liner

(GCL) Membrane • Appropriate RTC’s to suit location • Emplacement of suitable cover layers • Site wide Materials Management

Sighthill TRA Contract 1

Remediation Areas

Remediation Strategy

10

Upper cover layers Various types dependent upon end use and ground conditions

• Residential areas underlain by Galligu (and GCL) – 1m topsoil /subsoil over 1.5m site won soils

• Community Campus underlain by Galligu (and GCL) – 0.6m topsoil/subsoil over 1.9m site won soils

• Residential areas outwith Galligu – 1m topsoil/subsoil over 1m site won soils or natural material

• Landscape areas outwith Galligu - 0.6m topsoil/subsoil • Campus 150kN/m2 • Residential 50kN/m2

Sighthill TRA Contract 1

End of Contract 1 Site Levels

Sighthill TRA Contract 1

Preclassification • 1 per 250m3 • 400 trial pits • 1000 samples • Supplement SI Reclassification • Additional 2000 samples • Post treatment/processing

Sighthill TRA

• Match materials to criteria • Varying made ground • Varying chemical properties • Varying geotechnical properties • Varying potential • Suitable for one location but not an other • 3D thinking

Sighthill TRA Contract 1

Materials Management • Classification • Designation • Tracking • Processing • Compaction • Testing

Sighthill TRA Contract 1 Principal Quantities • 1800m long slurry wall up to 18m deep • 125,000m2 Geosynthetic Clay Liner GCL • 1,200,000m3 Materials Management • 26,500m3 Chemical Treatment by Stabilisation • 66,000m3 Geotechnical improvement including Galligu by

stabilisation • 2000m3 drilling and grouting drains up to 28m bgl • 350,000m3 processing by screening, crushing, segregation • 15000m3 tip material recycled multiple processes

Sighthill TRA Contract 1

Galligu What is it? That depends! Very wasteful by product from production of Sodium Carbonate (Soda Ash) Different production processes (United Alkali -26 companies) Different make up Different degrees of weathering and distribution Different appearances Different properties

Sighthill TRA Contract 1

Sighthill TRA Contract 1

Slurry Wall • Min 600mm wide • 1800m length • variable depth up to 18m

determined by probing • Cement/Bentonite/GGBS • Specification for the

Construction of Slurry Trench Cut off Walls

• Target permeability

Sighthill TRA Contract 1

Geosynthetic Clay Liner –GCL • Woven/Non woven fibre

reinforced • Needle punched Polypropylene

fibres • Polyethylene coating • Sodium Bentonite impregnated • Hydration from soil moisture • Minimum soil cover on

placement

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• Hotspots of arsenic, lead, sulphide, PAH and TPH identified

• Options appraisal identified stabilisation as most suitable option for remediation of discrete hotspots

• Stabilisation immobilises contaminants reducing leachability.

• Treated material to be placed under cover layers mitigating risks to human health

• Estimated Quantities 50% reduction through DQRA and delineation

Sighthill TRA Contract 1

Remediation of Contamination Hotspots

Sighthill TRA Contract 1

Treatment by Stabilisation • Leachability criteria • SEPA Mobile Plant License • Trials to determine additives • Conditioning/Incorporation • Control/Tracking • Verification

Sighthill TRA Contract 1

Materials Management • Classification • Designation • Tracking • Processing • Compaction • Testing

Sighthill TRA Contract 1 • 95,000m3 of galligu relocated • Former tip material excavated • Multiple processed- 99% recovery incl timber for bio mass

Sighthill TRA Contract 1

• Maximising reuse by processing • Sorting trials • Plant and process selection • Recover • Reclaim • Recycle • Renew • Revive • Regenerate

Sighthill TRA Contract 1 • Process efficiency • Plant selection Https://www.youtube.com/c/VHEConstructionBarughGreen The Regeneration Game

Sighthill TRA Contract 1

Sighthill Transformational Regeneration Area The next stage