Pride Park, Derby Nick Graham and Kevin Hargreaves.
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Transcript of Pride Park, Derby Nick Graham and Kevin Hargreaves.
Pride Park, DerbyPride Park, Derby
Nick Graham and
Kevin Hargreaves
IntroductionIntroduction
• 800,000m2 site, east of Derby city centre
• Enclosed by River Derwent and the railway
• Hosted a gasworks, unlicensed landfill and heavy engineering works
• Site was left heavily contaminated• £17.5m from government’s urban
development strategy, City Challenge
• Flat land → surface water drainage problems and risk of flooding
The ProblemThe Problem
• Parts of the gasworks and engineering works still remained
The Problem…The Problem…
• Heavily contaminated soil from past users– An unknown cocktail of
chemicals
• Methane gas being emitted from landfill site
• Surrounding land and river suffering from cross contamination
Possible SolutionsPossible Solutions
• Dig & Dump– Very large site, lot of
transport– Wouldn’t solve the problem
• Gas venting trenches– Methane is continuously
produced from landfill
Possible Solutions…Possible Solutions…
• Pump & Treat– Not effective alone
in long-term– Large site so need
containment barrier
• In situ bio-remediation
• 800 soil samples taken and tested for 22 different contaminants
The SolutionThe Solution
• Reclamation strategy developed by Arup to make site “suitable for end use”– Combination of possible solutions were used– Contain contaminants– Clean-up soil– Raise land level to reduce flooding risk
• 3km bentonite slurry cut-off wall– Up to 10m deep– 2mm HDPE membrane– Completed Dec. 2004
• Provision of a groundwater treatment plant– Abstraction wells around perimeter– Treat water and pump back in
The Solution…The Solution…
• Gas vent trench adjacent to existing landfill
• Two on-site, fully engineered, waste repositories
The Solution…The Solution…
– Contains excavated soil from site– Prevents removal off-site (shifting the problem)
• Use of "site won" and imported material to raise land– Pulverised fly ash
from local sources used as sustainable and cost-effective solution
The Solution…The Solution…
• Flood bund adjacent to the river
• Graded stone isolation layer or capillary break blanket
The Solution…The Solution…
• Land sold at market value (but with guarantee of no future problems), no council subsidies– £20m
The OutcomeThe Outcome
• Total cost to council (buying, reclaiming, infrastructure)– £50m
The Outcome…The Outcome…
• Council will breakeven in the future from high business rates from restaurants, retail, etc
Thank you for listening!