Simpson Park (Former Harworth Colliery) Remediation Strategy A098864_RS_V6
Harworth Group January 2020
3 Sovereign Square, Sovereign Street, leeds, LS1 4ER Tel: +44 (0)113 278 7111 Fax: +44 (0)113 219 2317 Email: [email protected] Website: www. wyg .com
WYG Engineering Limited. Registered in England & Wales Number: 01959704 Registered Office: 3 Sovereign Square, sovereign Street, Leeds, LS1 4ER
Simpson Park (Former Harworth Colliery) Remediation Strategy
Document control
Document: Remediation Strategy
Project: Harworth Colliery
Client: Harworth Group
Job Number: A098864
Report Reference A098864_RS_V6
File Origin: A098864\reports\A098864_RS
Revision: Draft 1
Date: December 2016
Prepared by: Checked by: Approved by:
Patricia Gill Iain Muir Patricia Gill
Description of revision: Draft for client comment.
Revision: V2
Date: February 2017
Prepared by: Checked by: Approved by:
Description of revision: Incorporation of client comments.
Revision: V3
Date: February 2017
Prepared by: Checked by: Approved By:
Iain Muir Patricia Gill Patricia Gill
Description of revision: Incorporation of additional information regarding below ground structures
January 2020 www.wyg.com creative minds safe hands
Simpson Park (Former Harworth Colliery) Remediation Strategy
Revision: V4
Date: February 2017
Prepared by: Checked by: Approved By:
Iain Muir Patricia Gill Patricia Gill
Description of revision: Edits to text in section 2.5 following additional client comment
Revision: V5.0 DRAFT
Date: September 2018
Prepared by: Checked by: Approved By:
Iain Muir Patricia Gill Patricia Gill
Description of revision: DRAFT for comment. Updated to reflect work undertaken at the site up to August 2018.
Revision: V6.0
Date: January 2020
Prepared by: Checked by: Approved By:
Iain Muir Patricia Gill Patricia Gill
Description of revision: Update to Enabling Works Upper 1m Criteria relating to calorific value.
January 2020 www.wyg.com creative minds safe hands
Simpson Park (Former Harworth Colliery) Remediation Strategy
Contents
1.0 Introduction ...... 1 1.1 Instruction ...... 1 1.2 Remediation Strategy Objectives ...... 1 1.3 Remediation Phasing ...... 3 1.4 Terminology ...... 4 1.5 Report Format ...... 4
2.0 Site Details ...... 6 2.1 Site Location ...... 6 2.2 Proposed Development ...... 6 2.3 Site Description ...... 6 2.4 Site History ...... 8 2.5 Anticipated Below Ground Structures ...... 9 2.6 Mining History ...... 12 2.7 Ground Investigation Works ...... 13 2.8 Published Geology, Hydrogeology and Hydrology ...... 14 2.9 Ground Conditions ...... 16 2.10 Ground Conditions in Ponds Area ...... 19 2.11 Groundwater ...... 19 2.12 Ground Contamination Summary ...... 20
3.0 Remediated Areas ...... 22 3.1 Phase 1C ...... 22 3.2 Coking Works ...... 22
4.0 Remediation Strategy ...... 25 4.1 Scope of Remediation Works ...... 25 4.2 Remediation Criteria, Enabling Works Upper 1m Criteria, Public Open Space (Park) Criteria, and Development Criteria ...... 26 4.3 Remediation Options ...... 28 4.4 Remediation During the Enabling Works ...... 30 4.5 Suitability of Material for Re-use ...... 35 4.6 Mine Shafts ...... 37 4.7 Remediation During Development Works ...... 37 4.8 Supervision ...... 41 4.9 Method Statements ...... 41 4.10 Health and Safety and Environmental Protection Considerations ...... 41
5.0 Contamination Verification Protocol ...... 43 5.1 General ...... 43 5.2 Chemical Verification ...... 43
January 2020 www.wyg.com creative minds safe hands
Simpson Park (Former Harworth Colliery) Remediation Strategy
5.3 Geotechnical Verification ...... 45 5.4 Verification Reporting ...... 45
6.0 Principles of Site Set Up and Environmental Control ...... 47 6.1 Environmental Controls during the Enabling Works ...... 47 6.2 Environmental Controls during the Development Works ...... 50
7.0 References ...... 51
Third Party Drawings Proposed Outline Masterplan, P16 5010 40 Rev D, JRP, 09.03.18. Ordnance Survey Plan Published 1983-1992, 1:10,000, Landmark Information Group on behalf of BWB Consulting. Site Features, UKC020HE/02A and UKC020HE/02B, BWB Consulting, 26.10.07. ‘No 1 Tower Service Duct’ (provided to WYG by Harworth Group) ‘Fan Drift’ x 2 (provided to WYG by Harworth Group)
Drawings A098864/LDS/N/101/Rev A - Site Location A098864/LDS/N/102/Rev A - Site Layout A098864/LDS/N/103/Rev C - Exploratory Hole Location Plan A098864/LDS/N/104/Rev A - Inspection Pit Location Plan A098864/LDS/N/108/Rev B - Historical Structures and Features A098864/LDS/N/109/Rev C - Areas of Anticipated Significant Underground Obstruction A098864/LDS/N/110/Rev A - Distribution of Made Ground A098864/LDS/N/113/Rev C - Identified Remediation Criteria Exceedances Requiring Treatment A098864/LDS/N/120 – Coking Works Constraints Plan A098864/LDS/N/121/Rev A –Stockpile Location Plan A098864-7/LDS/N/03 – Western Site & Ponds Remediation Criteria and Enabling Works Upper 1m Criteria Exceedances A098864-7/LDS/N/05 – Former Coking Works Remediation Criteria and Enabling Works upper 1m Criteria Exceedances
Appendices A - Report Conditions B – Planning Conditions C – Development Criteria for Private Gardens and Managed Landscaping and Criteria for Import D – Remediation Criteria, Enabling Works Upper 1m Criteria and Public Open Space (Park Criteria) E – Enabling Works Flow Chart
January 2020 www.wyg.com creative minds safe hands
Simpson Park (Former Harworth Colliery) Remediation Strategy
1.0 Introduction
1.1 Instruction
WYG Environment Planning Transport Ltd (WYG) was commissioned by Harworth Group (HG) to undertake environmental consultancy services including the production of a Remediation Strategy for the former Harworth Colliery site to support the proposed development of the site to residential end use. The site is located at Harworth, Nottinghamshire. A site location plan is provided as Drawing A098864/LDS/N/101.
This document sets out the general strategy for the proposed remediation and summarises how the works are to be implemented. The remediation strategy has been developed in conjunction with the earthworks strategy, which has also been prepared by WYG (2018b).
This Remediation Strategy relates to the area of the site shown on Drawing XA098864/LDS/N/102. Phase 1C is excluded from the area within this Remediation Strategy as its remediation was completed in line with V4 of the Remediation Strategy in February 2018. A masterplan for the site is shown on JRP Drawing P16 5010 40 presented in Third Party Drawings.
Remediation of an area known as the ‘Coking Works’ was completed in July 2018. Note the remediation work was limited to addressing significant contaminant linkages to groundwater. As risks to human health were not considered as part of the remediation works the Coking Works remains as an area to be addressed by this Remediation Strategy. Further assessment and remediation of groundwater contamination associated with the Coking Works is being addressed by others on behalf of Harworth Group as noted in Section 1.2 below.
Attention is drawn to the Report Conditions presented in Appendix A and the Terms and Conditions of the Engagement (Harworth Estates Framework Appointment of Consultant between Harworth Estates Ltd and WYG Environment Planning Transport Ltd).
1.2 Remediation Strategy Objectives
This Remediation Strategy summarises the principles, strategy and general method of approach to the proposed remediation works. This strategy takes into account the currently anticipated redevelopment of the site to one of predominantly residential end use, potentially incorporating elements such as a school. The proposed site development masterplan options
A098864 www.wyg.com creative minds safe hands 1
Simpson Park (Former Harworth Colliery) Remediation Strategy
(Drawing Ref: P16 5010 40) are presented in the Third Party Drawings section. It is anticipated that the development will include private gardens (including areas where vegetables may be cultivated and eaten by residents).
This document is specifically intended for submission to the Local Planning Authority to achieve the discharge of Planning Condition No. 25 of Application 61/09/00052 (presented as Appendix B). It is therefore intended this document will be agreed with Bassetlaw District Council (BDC), and, if deemed necessary by the Council, the Environment Agency (EA), prior to the start of works on site. The works will then be undertaken in accordance with and validated against this agreed strategy.
The enabling works and subsequent development works will be undertaken in a number of phases the details of which are yet to be confirmed. Therefore, details for each enabling works contract will be provided as part of the earthworks specification for those works which will incorporate the requirements of this remediation strategy. This remediation strategy will also be provided to tendering contractors.
Planning Condition 26 relates to assessment and remediation of groundwater relating to contamination associated with a former coking works present at the site. This element is being addressed by Wardell Armstrong on behalf of HG. A separate remediation strategy relating to groundwater has been prepared (Wardell Armstrong 2016) and agreed with the EA. Assessment and remediation of groundwater is therefore specifically excluded from WYG’s Remediation Strategy.
The site will be remediated adopting UK industry best practice and legislation with consideration for its intended end-use, taking into account the identified environmental receptors and human health with regard to the general setting of the site. This approach will consider practical aspects such as excavation limitations relating to depth, structural constraints, boundary matters, digging near utilities, health & safety matters, cost-benefit analysis etc.
The remediation strategy will seek to:
• Remediate the soil where significantly contaminated in order to reduce the impact from the site to sensitive receptors;
• Remediate contaminated structures or structures containing contaminated material e.g. tanks containing contaminated perched water or pipework lagged with asbestos;
A098864 www.wyg.com creative minds safe hands 2
Simpson Park (Former Harworth Colliery) Remediation Strategy
• Isolate the site users and infrastructure from residual contamination by means of hardstanding and a soil cover layer in areas of landscaping and residential gardens, where assessed to be required;
• Reuse as much soil as possible and in such a manner that any part of the site can be used for any proposed end use following the Enabling Works Remediation provided that the Development Remediation as detailed in this document is undertaken.
• Provide mitigation against the potential for ground gas to impact buildings and their occupants, where required.
• Implement an appropriate level of environmental control to protect off-site receptors and undertake appropriate environmental monitoring to demonstrate that the works do not cause significant impact, followed by short-term monitoring to demonstrate ongoing compliance.
The strategy has been designed to practically minimise the risks to receptors whilst also being a strategy emphasising a sustainable and cost beneficial approach. The strategy is therefore one of environmental risk reduction which seeks to reduce the impact on receptors by source treatment and removal and/or by the breaking of contaminant linkages by the breaking of pathways for contamination.
Throughout the proposed works consultation with BDC will be maintained and any proposed variations to this Remediation Strategy which may derive from ground conditions encountered during the works, will be discussed with BDC prior to implementation.
1.3 Remediation Phasing
The precise phasing of development of the site has not been concluded. At the time of writing it is broadly anticipated to involve development from east to west across the site and that the remediation will be undertaken in phases during both the Enabling Works and the Development Works. Remediation in Phase 1C has been completed and consequently is excluded from this assessment.
Within this document managed landscaping relates to the POS and all areas of publicly accessible soft landscaping (e.g. landscaping adjacent to highways, roundabouts, public amenity space, etc) and is hereafter referred to as managed landscaping.
The Enabling Works remediation will be monitored by a representative of the Supervisor under the Contract to check that the appropriate remediation standards and the
A098864 www.wyg.com creative minds safe hands 3
Simpson Park (Former Harworth Colliery) Remediation Strategy
environmental controls are achieved and that the works are undertaken in accordance with this document.
The Enabling Works will include the following remediation works:
• Targeted excavation of Identified Remediation Criteria Exceedances Requiring Treatment identified on Drawing A098864/LDS/N/113.
• Earthworks cut and fill to achieve site formation levels including placement of soils exceeding the Enabling Works Upper 1m Criteria at depth.
• Testing of soils to demonstrate suitability for reuse.
• Decommissioning of standpipes with response zones targeting the Principal Aquifer.
The Development Works will include the following remediation works:
• The installation of a cover layer in private gardens where vegetables for consumption may be grown, except where areas of earthworks cut expose natural ground. Further details are provided in Section 4.
• The installation of a cover layer in areas of managed landscaping, except where areas of cut expose natural ground. Further details are provided in Section 4.
• Use of barrier polyethylene or metal water pipes within made ground.
• The installation of ground gas protection measures in buildings (where required).
1.4 Terminology
The following terminology has been used within this document in relation to levels:
• Final Development Level = the level following the construction of gardens/ open space.
• Restoration Level = the level of areas for development following completion of the Enabling Works i.e. 0.6m below Final Development Level.
1.5 Report Format
The format of this Remediation Strategy document is as follows:
Section 2 provides a summary of site details and site conditions.
Section 3 provides a summary of areas where remediation has already been undertaken.
A098864 www.wyg.com creative minds safe hands 4
Simpson Park (Former Harworth Colliery) Remediation Strategy
Section 4 provides a description of the remediation works proposed.
Section 5 summarises the verification protocol.
Section 6 provides details for site set up and environmental controls.
A098864 www.wyg.com creative minds safe hands 5
Simpson Park (Former Harworth Colliery) Remediation Strategy
2.0 Site Details
A description of the site and the main findings of the previous environmental assessments are summarised below. Details relating to the whole of the assessment area are given with specific reference to individual development parcels as appropriate. The information has been obtained from WYG 2016a and WYG 2016b (factual and interpretative ground investigation reports).
2.1 Site Location
The site is located in Harworth approximately 12 km south of Doncaster city centre. Access to the site is from Blyth Road on the site’s western side via a dedicated entrance and road. A site location