Pride Park, Derby

1
Pride Park, Derby

• Nick Graham and
• Kevin Hargreaves

2
Introduction

• 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 governments urban development
  strategy, City Challenge

3
The Problem

• Flat land ? surface water drainage problems and
  risk of flooding

• Parts of the gasworks and engineering works still
  remained

4
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

5
Possible Solutions

• Dig Dump
• Very large site, lot of transport
• Wouldnt solve the problem
• Gas venting trenches
• Methane is continuously produced from landfill

6
Possible Solutions

• Pump Treat
• Not effective alone in long-term
• Large site so need containment barrier

• In situ bio-remediation

7
The Solution

• 800 soil samples taken and tested for 22
  different contaminants

• 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

8
The Solution

• 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

9
The Solution

• Gas vent trench adjacent to existing landfill
• Two on-site, fully engineered, waste repositories

• Contains excavated soil from site
• Prevents removal off-site (shifting the problem)

10
The Solution

• Use of "site won" and imported material to raise
  land
• Pulverised fly ash from local sources used as
  sustainable and cost-effective solution

• Flood bund adjacent to the river
• Graded stone isolation layer or capillary break
  blanket

11
The Solution
12
The Outcome

• Land sold at market value (but with guarantee of
  no future problems), no council subsidies
• 20m

• Total cost to council (buying, reclaiming,
  infrastructure)
• 50m

13
The Outcome

• Council will breakeven in the future from high
  business rates from restaurants, retail, etc

Thank you for listening!