REMEDIATION OF INCE CENTRAL ESTATE IN WIGAN A Part 2A Site Tony Brown, SiLC – Director of Ground Engineering John Crowther, SiLC - Technical Director 22 nd September 2009

1 Contaminated Land & Brownfield Remediation Conference Ince Central Estate, Wigan

2 Contaminated Land & Brownfield Remediation Conference Site Location Plan

3 Contaminated Land & Brownfield Remediation Conference Estate Layout

4 Engineering & Environment Conference 2008 Ince Central Estate, Wigan – Remediation Project John Crowther – from Investigation to Options Appraisal Tony Brown – Trials and Remediation Works

5 Engineering & Environment Conference 2008 From Investigations to Options Appraisal I Supplementary Desk Study Supplementary Site Investigation Groundwater issues assessed as not critical Additional investigation carried out including sampling within top 1m within each garden plot Further investigation within ‘clear’ plots

6 Contaminated Land & Brownfield Remediation Conference Composite Historical Plan

7 Contaminated Land & Brownfield Remediation Conference GI Plan

8 Contaminated Land & Brownfield Remediation Conference Results with Averaging Areas Shown

9 Engineering & Environment Conference 2008 From Investigations to Options Appraisal II Human Health Risk Assessment Derivation of Site Specific Values (SSV’s) – BP RISC (organics) – SNIFFER (inorganics) Sensitivity Analysis – Arsenic (including PBET)

10 Contaminated Land & Brownfield Remediation Conference Arsenic SSV Derivation - 1 Value mg/kg150Utilises BP RISC model. Assumptions:- soil eating by child up to 6 years of age on 180 days per year as indicated on Table 6.1 of CLR % bioavailability child body weight 14.5kg 89Utilises BP RISC model. Assumptions:- soil eating by child up to 6 years of age on 365 days per year as indicated on Table 4.3 of CLR 10 (discrepancy between tables in CLR10 reported to Environment Agency) 40% bioavailability child body weight 14.5 kg 55Utilises BP RISC model. Assumptions:- soil eating by child up to 6 years of age on 365 days per year as indicated on Table 4.3 of CLR 10 (discrepancy between tables in CLR10 reported to Environment Agency) 70% bioavailability child body weight 14.5 kg

11 Contaminated Land & Brownfield Remediation Conference Arsenic SSV Derivation Utilises BP RISC model. Assumptions:- soil eating by child up to 6 years of age on 365 days per year. 100% bioavailability (following meeting of ) child body weight 14.5 kg 38Utilises BP RISC model. Assumptions:- soil eating by child up to 6 years of age on 365 days per year. 100% bioavailability. child body weight 14 kg. 27 Utilises SNIFFER model (for metals only) following meeting of Assumptions:- soil eating by child up to 6 years age on 365 days per year 100% bioavailability child body weight 14kg

12 Engineering & Environment Conference 2008 The Appraisal Criteria 1.Impact on residents’ health and quality of life 2.Technical feasibility and sustainability 3.Statutory powers and duties 4.Cost and potential availability of funding 5.Impact on structures, services and foundations 6.Timescales 7. Risks (to delivery of solution) 8. Opportunities 9. Impact on tenants 10. Impact on homeowners 11. Impact on the estate image 12. Wigan Council Housing Strategy and other strategies

13 Contaminated Land & Brownfield Remediation Conference

14 Engineering & Environment Conference 2008 Liaison with Residents Only one initial public meeting ‘History’ Day Interviews – Consultant and Remediation Contractor Resident’s Liaison Group Participation Regular Newsletters Home Visits HPA Health Consultation Days 3 Stakeholder Meetings

15 Engineering & Environment Conference 2008 Trials & Remediation Works Pilot Project –Pair of semi-detached properties undertaken in May 2005 Remediation of the first two Phases (1 & 2) –32 plots in northern part of the estate Lessons learnt for other phases ‘Architectural Details’ Conclusions

16 Engineering & Environment Conference 2008 Remediation Works – Pilot Project Reasons for undertaking the pilot –to establish whether residents can remain in their homes without risk to their health. –to confirm feasibility of methodology adopted. –to enable residents to appreciate the nature of the works to be undertaken. Selection of the pilot –vacant properties –good access –contaminated material encountered

17 Contaminated Land & Brownfield Remediation Conference Remediation Works – Pilot Project 44 & 46 The Grove

18 Contaminated Land & Brownfield Remediation Conference Remediation Works – Pilot Project

19 Engineering & Environment Conference 2008 Remediation Works – Pilot Project Two techniques implemented –Excavate & Replace (600mm) –“Capping” (200mm) Environmental Monitoring –Air Quality (PM10, Nuisance Dust, Dust Analysis) –Noise and Vibration Suitable import materials identified

20 Contaminated Land & Brownfield Remediation Conference Remediation Works – Pilot Project

21 Contaminated Land & Brownfield Remediation Conference

22 Contaminated Land & Brownfield Remediation Conference View prior to work commencing (44 The Grove)

23 Contaminated Land & Brownfield Remediation Conference Excavation in progress (rear of 44 The Grove)

24 Contaminated Land & Brownfield Remediation Conference Damaged drain (44 The Grove)

25 Contaminated Land & Brownfield Remediation Conference Repaired drain (44/ 46 The Grove)

26 Contaminated Land & Brownfield Remediation Conference Base of excavation (44 The Grove)

27 Contaminated Land & Brownfield Remediation Conference Filling with sandy subsoil (44 The Grove)

28 Contaminated Land & Brownfield Remediation Conference Topsoil placed (44 The Grove)

29 Contaminated Land & Brownfield Remediation Conference New fencing erected. Topsoil placed and trees planted at rear of 46 The Grove

30 Contaminated Land & Brownfield Remediation Conference Patio area being constructed (46 The Grove)

31 Contaminated Land & Brownfield Remediation Conference Turf laid (44 The Grove)

32 Contaminated Land & Brownfield Remediation Conference Excavation in progress (46 The Grove)