1. Further Site Investigation Sutton Walls Former Landfill
Katy Baker
Technical Project Manager
ARCADIS EC Harris

2. Contents Part 2A legislation Background to the site
What’s happened so far?
The outstanding issues
Further site investigation
Further site investigation findings
Recommendations and next steps

3. Part 2A legislation The ‘Contaminated Land Regime’ Introduced in 2000
Local Authorities are the prime regulators
Introduces the ‘contaminant linkage’
Source ► Pathway ► Receptor
Investigation and risk assessment followed by remediation if required
Adheres to the ‘polluter pays principle’
Environment Agency (EA) manages ‘Special Sites’ 3

4. 4 Categories 4

5. Background to the site
Former gravel workings inside an Iron Age fort designated a scheduled ancient monument (SAM)
Domestic and Industrial solid and liquid waste deposited
Operated as ‘dilute and disperse’ facilities
Concerns of historical surface leachate emissions and water pollution
Former waste operators establish a water monitoring network including sampling private drinking water supplies
Health concerns raised by local community 5

6. What’s happened so far?
Investigation and sampling of the landfill and surrounding land, including private water supply sampling, took place in late Jan – late April 2012
No drinking water supplies contain chemicals derived from the landfill that are harmful to human health
Surface water and soils meet environmental quality standards
Several groundwater boreholes contained elevated levels of some chemicals
Presence of ethanal and arsenic in ambient air above the landfill
Exceedances of vinyl chloride in two boreholes in the land around the landfill

7. The Outstanding Issues
Further data collection required to assess whether gas is being generated from compounds in groundwater beneath the land surrounding the landfill, which could present a risk to local residents in the houses closest to the landfill
Further ambient air sampling and evaluation of the data to assess is there is a risk to people visiting the landfill or using the pathway which runs around the landfill (e.g. dog walking, running). 7

8. Further Site Investigation
Building assessments undertaken in December 2013 to understand building construction/use of each property
Drilling works undertaken in mid Dec 2013
Twelve deep boreholes in the gardens of individual properties
Seven shallow boreholes in the gardens of individual properties
3 week continuous monitoring at 3 locations
Sampling of deep and shallow soil gas (3 visits)
Indoor air sampling of properties (3 visits)
Outdoor air sampling in the surrounding land (3 visits)
Ambient air samples on landfill & surrounding path (3 visits)
Risk assessment based on use of landfill and surrounding land

9. Samples from here
Samples from here
Samples from here
Samples from here

10. Samples from here (multiple locations around the landfill)
Emissions to air
Natural Soils/Rock
Landfill
Footpath around
landfill

12. 12

13. Investigation Tools
Continuous gas monitoring system (monitors for gases such as carbon dioxide and methane over time)
Sampling canisters (collects a canister of soil gas, analysed by a laboratory to see if it contains chemical compounds)
Sorbent tubes (air passes through the tube over time, chemical compounds are retained and tube sent for analysis) 13

14. 14

16. Site Investigation Findings – Surrounding Land
Substances found in soil gas but which met standards protective of human health (risk evaluation assumed a young child could live in each property); key compound of concern, vinyl chloride, not detected
Substances found in indoor and outdoor air but not attributable to gases generated from tipped substances in the landfill; key compound, vinyl chloride, not detected
The substances in indoor air are attributable to common background sources (e.g. furniture polish, cleaning fluids) and are at levels which do not pose a significant risk to those living at the properties 16

17. Vinyl chloride not
detected in indoor or outdoor air
Vinyl chloride not
detected in soil gas

18. Site Investigation Findings - Landfill
Site survey combined with local knowledge used to identify how the landfill and surrounding path is used for recreational purposes (e.g. dog walking, joggers)
Substances detected in ambient air were evaluated using this knowledge about the site
The conclusion was that substances detected in ambient air above the landfill are at levels which do not pose a significant risk to normal recreational users and conditions are not expected to deteriorate over time 18

19. Low level detections of substances in ambient air
Emissions to air
Natural Soils/Rock
Landfill
Footpath around
landfill

20. Site Investigation Findings – Category 420

21. Recommendations and next steps
Decommissioning of boreholes at residential properties
Recommendation that risks as defined under Part 2A of the Environmental Protection Act are not significant (falls within Category 4)
Continued recommendation that groundwater is not used from private wells present on properties
Present final report to Parish Councils Nov 2014.