Pride ParkPride ParkContaminated Land SiteContaminated Land Site

byby

Angela Varley, Kar-Wai WongAngela Varley, Kar-Wai Wong

The SiteThe Site

Facts

80Ha site

Bordered by the River Derwent, and a railway line

The SiteThe Site

Previous park usage was:Litchurch coke & gas works since 1900sBritish Rail Locomotive works & sidingsGravel abstractionIndustrial and domestic landfill

The Modern EraThe Modern Era

Ove Arup & Partners employed to Ove Arup & Partners employed to create an engineering solution which create an engineering solution which waswasEnvironmentally responsibleEnvironmentally responsibleSustainableSustainableCommercially viableCommercially viableBased on sound engineering principlesBased on sound engineering principles

Finding the ProblemFinding the Problem Site was investigatedSite was investigated

‘‘The big problem was that nobody knew the full extent of the The big problem was that nobody knew the full extent of the contamination which had accumulated over 160 years since the contamination which had accumulated over 160 years since the locomotive works started operating there,’ said project manager locomotive works started operating there,’ said project manager Gethyn Davies.Gethyn Davies.

800 soil samples 800 soil samples takentaken Tested for 22 Tested for 22 contaminants including:contaminants including:

•OilsOils•TarsTars•Heavy pollutantsHeavy pollutants•RadiationRadiation

The ProblemThe Problem It lay redundant and blighted by its previous usesIt lay redundant and blighted by its previous uses

Site hazards included:Site hazards included: Soil and groundwater contaminationSoil and groundwater contamination

Ammonia, oils, tars, heavy metals, boron, coal,Ammonia, oils, tars, heavy metals, boron, coal, creosote, phenols, sulphates

Buried concrete structuresBuried concrete structures Loosely consolidated fillLoosely consolidated fill Low level radioactive wasteLow level radioactive waste A relatively flat area giving rise to surface drainage problemsA relatively flat area giving rise to surface drainage problems Tip producing methane gasTip producing methane gas

Alternative SolutionsAlternative Solutions

Biological in-situBiological in-situPhytoremediation

Sustainable method

Chemical and biological process

Removes water soluble contaminants

Treatment wallTreatment wallPorous (holey) wall

Contaminants filtered out, clean water passes through

Not used at Pride Park due to risk of ineffectiveness

Solution overviewSolution overview Bentonite wallBentonite wall

At three kilometres long it is the largest of its kind in Europe, costing At three kilometres long it is the largest of its kind in Europe, costing £1.6m£1.6m

Panels sunk to a depth of 10 metres below the surfacePanels sunk to a depth of 10 metres below the surface A type of mineral deposit consisting principally of montmorillonite clay. A type of mineral deposit consisting principally of montmorillonite clay. Bentonite has a very high surface area, and when fully hydrates Bentonite has a very high surface area, and when fully hydrates

becomes very viscous.becomes very viscous.

Solution overviewSolution overview

Water containment measuresWater containment measures Flood bundFlood bund Raise level of siteRaise level of site

Self contained treatmentSelf contained treatment Groundwater treatment plantGroundwater treatment plant Waste repositoriesWaste repositories

Implementation of SolutionImplementation of SolutionTrench excavated

Trench kept open by filling with slurry

As excavate, soil-bentonite backfill placed into trench, displacing bentonite-water slurry