Land Contamination, Restoration and Revegetation Report

Land Remediation Report: techniques to treat contaminants at the Croda site, Kilnhurst

LSC 305 Land Contamination, Restoration and Revegetation

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Contents

1.1 Introduction 1.2 Site Context

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Site History

Overview of the Sites Background

2.1Current Site Condition

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Vegetation and Topographic Survey Information

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3.1 Conceptual Site Model of the Site

4.1 Tabulated information on potential contaminants on the Croda site

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4.2 Remediation techniques to be implemented at the Croda site Water remediation techniques for the Croda site Soil remediation techniques for the Croda site Revegetation techniques for the Croda site

4.3 Conclusion

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Bibliography References

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1.1 Introduction

By analysing the past industrial uses of the Croda Site, situated at Kilnhurst, South Yorkshire, a hypothesis can be constructed to determine what potential contaminants have affected the sites context and suggestions can be made to which remedial techniques can be implemented to restore and enhance the current condition for future uses, such as housing, and provide vital improvements to the environment. Due to the close proximity to housing developments and surface watercourses this heavily contaminated land poses a great threat to the surrounding communities. As this site is currently being designated to housing within the local development plan this report aims to provide an analysis of the potential sources, pathways and receptor linkages that pose threat upon any future development taking place and find a suitable way to dealing with these contaminants.

1.2 Site Context

The site is located between Kilnhurst and Swinton on the outer periphery of Rotherham and is located east of large housing developments and west of the South Yorkshire navigation Canal. On the eastern side of the site lies a railway line that is currently in use that lies between the site and housing development. Surrounding the site is agricultural land, the River Don and open unused land.

Site History

During the industrial revolution the Croda site has been used for industrial usage and subsequently contaminating the land to present day. During the 1880s Mitchell and Ellison established a coal distillation and processing facility on the site producing large amounts of coke that was valuable to fuelling furnaces and contributing to the manufacturing of steel in Sheffield. Sheffield’s demand for producing steel caused a large number of refineries and factories to open across the South Yorkshire area. Toxic chemicals, such as benzene and xylene, were produced on the site as these would have been extracted from the tar. It was in the 1920s that the site became known as the Yorkshire Tar Distillers where tar distillery creosote was being refined for preserving timber and the site housed large storage tanks. However in the 1970s tar production was replaced by petroleum that required long chain chemicals that were then perceived as being less harmful. In 1975 the company changed hands and was renamed to the Croda site.

Site Location

Site Location

Agricultural Land

Housing Development

Past/Present Industrial sites

South Yorkshire Canal

Railway line

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By 1981 the distillation of tar ended therefore the factory only produced bitumen up till its closure in 1998.

As the refinement of bitumen products were taking place, polymers were added to expand the uses from road emulsions and sealants. Consequently lower energy levels were needed in production that meant that handling these products became safer in comparison to past refinement processes. Despite this large levels of concentrated hydrochloric acid were produced that posed a great threat to the local wildlife and environment.

Overview of the Sites Background

Carlisle Street divides the site and creates two separate parts of the whole site. The South Site contained the refineries and factories that were established in the 1880s whereas the North Site has been a waste material disposal area for Yorkshire Tar Distiller’s since the 1940s and has subsequently been used in a similar manner up to the sites closure in 1998.

2.1 Current Site Condition

Currently the site undergoing remedial works although the site has been derelict since the industrial buildings were decommissioned and the sites closure in 1998. North Site is being designated for housing within the local development plan after remediation works have been successfully completed.

North Site contains a range of waste products such as the run out of pitch into clinker/ ash bunds, this residual pitch that is still present in the area. Due to a failure with an exposed storage tank large spillages of bitumen and tar have let contaminants spread throughout the site. This occurred when an earth bund was removed to create a pond that in turn used the sand and gravel aquifer causing the spread of contamination across the site. The South Site however has not yet undergone any remediation treatment.

Geological Survey

Using information from site investigation and the British Geological Survey map of the area the site contains made ground (between -0.5m – -2m) consisting of sand, gravel, silt and demolition rubble.

According to the Environment Agency (EA) this made ground is non-aquifer. While beneath lies alluvial deposits (between -1m- -5m) again considered to be a minor aquifer of varying levels of permeability. Groundwater lies predominantly within these alluvial deposits (4.5m approximately). Upper Carboniferous Middle Coal Measures (up to -15m) lie beneath this layer of alluvial deposits and these consist of siltstone, seat earth, coal and mudstone to an ultimate depth of 1500m approximately. These coal measures are minor aquifer of varying levels of permeability according to the EA. Vegetation and Topographic Survey Information

The site is relatively flat with rubble mounds made up of past building materials, the railway line is raised 5m approximately from the rest of the site while vegetation is very limited across the south of the site with remnants of pat buildings still prevalent. Due to a thin layer of low nutrient and compacted soil covering the south of the site there is limited grass and scrub vegetation present currently.

However the North Site contains a more established quality of vegetation with small-medium tree growth and evidence of dense shrub growth.

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This conceptual model helps to consider where possible contaminants should be intercepted to prevent them reaching a receptor, such as near by residents. It is a simplified model to represent the current system in place that has been created through site information and field analysis.

To help creating mitigation plans and considerations for land reclamation the model enabled sound understanding of the processes currently on site. This model is adaptable and can be further updated through this process to ensure a stronger hypothesis based upon recording evidence of potential threats to receptors and further investigate specific parts of the site containing contaminants and evaluate the receptors vulnerability to these.

3.1 Conceptual Site Model of the Site

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4.1 Tabulated information on potential contaminants on the Croda site Contaminant

Threat posed

Source and LocationDetails

Asbestos

Carcinogenic particularly when airborne

North Site: Found in waste disposal areas and soil of made ground mounds.

South Site: In soil and rubble of made ground

Arsenic

Heavy metal that is highly toxic potentially causing death to humans, spreads fast by wind blown dust, enters water from leaching and run-off water, can not be decomposed in the environment just taking different forms

Copper

Lead

North Site: Due to disposal traces can be found in made ground. South Site: Made Ground, Shallow groundwater, Found surrounding refinery locations and site storage areas, located near canal and railway line North Site: Due to disposal traces can be found in made Heavy metal that is movement through soil ground. South Site: is reduced by clay Made Ground, minerals and organic Shallow matter, High exposure groundwater, Found can be irritant to skin surrounding refinery with low levels of locations and site toxicity storage areas, located near canal and railway line North Site: Due to Heavy metal that is disposal traces can highly toxic to the be found in made human nervous ground. South Site: system, travels long Made Ground, distances in air before Shallow settling to the ground, groundwater, Found Clay minerals and surrounding refinery organic matter reduce locations and site the rate and chances of storage areas, located near canal movement and railway line

Does not dissolve in water or evaporate in air, carried long distances by wind or water before settling yet cannot move through soil

Movement is limited by clay minerals and organic matter, more soluble in alkaline conditions, Rain removes Arsenic dust particles

Cannot be broken down by the environment, found mostly at the East of South Site

Movement from soil to groundwater is dependant on the type of soil and lead compound, found predominantly at the East of the South Site

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North Site: Made Ground, Ground water- Surface Highly volatile organic water, Chemical compound, easily disposal pits. South mobile through soil and Site: Made ground, groundwater Ground- Surface movement, Toxic and water, Storage Tanks known to cause cancer (underground), Spillages from refinery operations

Breaks down slowly in soil and water, Evaporates quickly in the air, colourless with sweet odour, Widely spread throughout the whole site

Ethylbenzene

Highly Volatile and mobile Organic Compound through soil and groundwater, Toxic to humans with untreatable damage to ears after exposure for a period of a few days

North Site: Made Ground, GroundSurface water, Chemical disposal pits. South Site: Made Ground, Ground- Surface water, Storage Tanks (Underground), Spillages from refinery operations

Breaks down in surface water by reacting with naturally occurring chemicals and by bacteria within the soil, Easily evaporated from the soil and water into the air, Low aqueous solubility- sinking into ground water

Xylene

Volatile Organic Compound carried along pathways for long distances, Prolonged exposure to high levels of Xylene can be toxic to humans, Highly flammable

North Site: Made Ground, Ground water- Surface water, Chemical disposal pits. South Site: Made ground, Ground- Surface water, Storage Tanks (underground), Spillages from refinery operations

Quickly evaporates from surface water and soil into the air, has small cumulative affect on ecosystems, microorganisms break down xylene, sunlight turns it into non-toxic chemicals within days

Benzene

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Pathway

Vulnerable Receptors Implications

Site workers, Future residents on site, Nearby communities such as dog walkers, fisherman, current trespassers and other visitors (including animals)

These people affected through soil disturbance on site, evaporating surface water, air bourn particle inhalation of asbestos and Lead from the sites immediate and local community with potential risk to wider context

Site workers, Future/ current residents and animals, especially if food is grown on site

It is vital to remove hazardous materials from the future housing development site, therefore this is high risk

Contact with skin

Site workers, intruders/trespassers, animals, future residents

Disrupting and disposing of soil can be a hazardous factor, exposure during and after development process

Movement through groundwater and made ground soil

Contaminants could potentially move Ecosystems and habitats in the through groundwater canal/River Don leading into canal networks, Sewage and system and River water pipes could have Don, surface run off direct affect on water allowing residents contamination around the site

Hydraulic Infrastructure

Present/ future residents

Inhalation

Ingestion

Leaching into water pipes will affect local community

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4. 2 Remediation techniques to be implemented at the Croda site

As this site is being considered for housing within the local plan then remediating contaminants currently present on the site is vitally important. Any proposed development on a contaminated site must not have started construction before all remediation techniques have been completed. This is noted in the National Planning Policy Framework- Statement 121 outlining that any site with proposed new uses must be suitable for that particular use and a range of issues being dealt with such as the consideration of ground conditions and land instability while also taking into account the sites ‘‘natural hazards or former activities such as mining, pollution arising from previous uses and any proposals for mitigation including land remediation or impacts on the natural environment arising from that remediation’’. Reducing and ending pathways between receptors and sources can be achieved through a range of landscape remediation techniques.

Water remediation techniques for the Croda site

Permeable reactive barriers are a relatively expensive option for treating contaminated groundwater yet is effective in preventing contaminants from entering nearby canal and river systems.

Conversely a more economically viable and common technique is to use the pump and treat method in treating water soluble contaminants however this technique can not always be appropriate in successfully treating groundwater on a site. As this is a relatively fast approach this is useful for a development scheme to get the proposal underway but at the same time by pumping out the contaminants out of the aquifer and treating them at the surface there are risks in that the contaminants can enter surface water and also be reintroduced to the groundwater level.

Soil remediation techniques for the Croda site

For soil remediation materials from any built remains on the site must be removed and taken to a suitable disposal plant, under sufficient cover from wind and in specially adapted vehicles, these include materials such as any visible asbestos or heavy metals as these can not be effectively treated with revegetation on any given site. Leaching occurring on the site in high level contaminated soils must be remediated by being removed off to a specified site or can be mixed with a reagent causing a chemical reaction to significantly reduce the transportation of a contaminant.

However removal of such large quantities of contaminated soils is economically unsustainable for a large site such as Croda therefore capping would be suitable for dealing with the breakage of pathways between the source of contamination and vulnerable receptors by covering the contaminated soil with compacted clays or synthetic fibers. Barrier capping is more easily applied to keeping contaminants from the surface of a part of a site yet it must be inspected and maintained permanently to ensure that there are no breakages and that the contaminated soils are contained from air and also from leaching into surrounding areas. Despite this leaching of contaminants is much more difficult to deal with and therefore If natural attenuation is proposed as the mechanism remediating a groundwater plume, then natural attenuation processes must be verified on the site before this solution can qualify as a soil performance standard. As heavy clay is present within the site then this approach is more economically feasible to be implemented to deal with contaminates than excavating and disrupting the material off the Croda site. This technique prevents pollutants migrating due to rain and surface water run off to surround areas and also through wind spread forms of movement.

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Soil Vapor Extraction of contaminants is another technique that can be used, in both the North and South Site, to reduce mobility of contaminants such as Volatile Organic Compounds. The use of air being passed through the made ground soils alongside chemical oxidation will reduce the contaminant very effectively. Stabilisation would be suited to the North site due to high quantities of lime deposited there, by using a solidifying agent the contaminants within the soil would be less prone to subsidence into groundwater and could be kept in isolated areas of the site to prevent spread.

This would isolate heavy metals such as Lead, Copper and Arsenic within the Croda site and would not have to be taken to select landfill sites. Lime should be neutralised and should not be moved due the threats this has for air quality. Due to the contaminants not being removed from the site this approach will prove effective due to the short time scale given to meet the housing plans and the immediate impact this will have for the proposed housing development, despite thorough monitoring of the stabilisation system set in place in the future.

Revegetation techniques for the Croda site

using reed bed planting should be implemented alongside the River Don and Canal to treat and reduce contaminants. Possible pools of water on site could be implemented to treat spillages particularly in the North Site where disposal of contaminants such as bitumen were placed. At the same time large amounts of sediment from the ground would have to be taken off site to produce a successful reed bed filtration system.

4.3 Conclusion

Through analysing these methods of restoring the site to a state suitable for housing, while providing improvements to the local wildlife, local flora and surrounding communities, a series of restorative approaches must be taken. Due to the nature and complexity of the sites past uses these methods should be employed: Revegetation • Planting reed beds • Using mixed species such as Willow and Alder across canal and waters edge • Slow growing trees with larger root systems will be more effective for dealing with contaminants in soil • Plant ‘Buckshot’ species for appearance for future developers and users • Implement species good for coppicing, such as Birch or Willow species, this will provide hedging from trespassers during remediation period and provide good vegetation growth fro the Croda site Soil Treatment • New topsoil for future housing gardens (expensive) • Provide a membrane to prevent people digging into contaminated soils • In situ technique of capping membranes to isolate contaminates such as lime.

• Soil Vapor Extraction and chemical oxidation on the site to deal with volatile organic compounds such as Benzene, Ethylbenzene, Xylene • Using Permeable Reactive Barriers to reduce the impact of contaminated groundwater on Croda site • Careful modifications to in situ capping materials in the future to not allow any spillages on the new developed site These methods of treatment should be applied at different times necessary and this report should be altered as the project unfolds, new findings may shape more informed decisions about the best possible remediation methods at different points in the reclamation process.

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Bibliography DEFRA (2013) Untitled. [online] Available at: http://www.defra.gov.uk/environment/quality/land/ [Accessed: 9 Apr 2013].

Eea.europa.eu (2013) Air quality in Europe — 2012 report —. [online] Available at: http://www.eea.europa.eu/publications/air-quality-in-europe-2012 [Accessed: 9 Apr 2013].

Environment-agency.gov.uk (2002) Environment Agency - Commercial and industrial waste in Wales 2002-3. [online] Available at: http://www.environmentagency.gov.uk/research/library/publications/103522.aspx [Accessed: 10 Apr 2013].

Jochimsen, M. (2013) Vegetation development and species assemblages in a long-term reclamation project on mine spoil.. 4th ed. Ecological Engineering 17, p.180-198.

Landclean.net (n.d.) Land Remediation After Care. [online] Available at: http:// www.landclean.net/aftercare.htm [Accessed: 8 Apr 2013].

NPPFCommunities and Local Government (2012) National Planning Policy Framework . [online] Available at: https://www.gov.uk/government/uploads/ system/uploads/attachment_data/ file/6077/2116950.pdf [Accessed: 6 Apr 2013].

Unknown. (1996) Reclamation of damaged land for nature conservation . 5th ed.

London: HMSO. Unknown. (2013) Soil Performance Standards, Remediation & Redevelopment Program 3. [online] Available at: http://dnr.wi.gov/files/PDF/pubs/rr/RR528. pdf [Accessed: 7 Apr 2013].

References

Planning Policy Guidance for Housing PPS3 (n.d.) Planning Guidance Notes and Statements. [online] Available at: http://www.planning-applications.co.uk/ppgs. htm [Accessed: 10 Apr 2013].

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