land contamination, restoration and revegetation report- croda site

Croda Site: Contamination ReportA Study of the site Contaminants, potential sources,

pathways and proposed mitigation measures

LAND CONTAMINATION

LSC305 Land Contamination, Restoration and Revegetation

Registration Number:100214020

RESTORATION AND REVEGETATION

Content1. Introduction

- 1.1. Report aims and Methodology.....................................................................................................page 1- 1.2. Site History...................................................................................................................................page 1- Fig.1....................................................................................................................................................page 1

2. Baseline Information

- 2.1. Site Location................................................................................................................................page 2- Fig.2....................................................................................................................................................page 2- 2.2. Current SIte Conditions................................................................................................................page 3- 2.3. Topography.................................................................................................................................. page 3- 2.4. Geological Conditions..................................................................................................................page 3- 2.5. Built Form.....................................................................................................................................page 4- 2.6. Vegetation....................................................................................................................................page 4

3. Conceptual Site Model

- 3.1. Conceptual Site Model (CSM) Definition......................................................................................page 5- Fig.4....................................................................................................................................................page 6

4. List of Site Contaminants

- 4.1. Heavy Metals...............................................................................................................................page 7- Fig. 5...................................................................................................................................................page 7- 4.2. Volatile Organic Compounds (VOCs).........................................................................................page 8- Fig.6....................................................................................................................................................page 8- 4.3. Asbestos......................................................................................................................................page 9- Fig.7....................................................................................................................................................page 9- Fig.8....................................................................................................................................................page 9- Fig.9....................................................................................................................................................page 9- Fig.10..................................................................................................................................................page 9- Fig.11..................................................................................................................................................page 9

5. Tabulated Linkages

- 5.1. Potential Pathways and Receptors.............................................................................................page 10- Fig.12................................................................................................................................................page 10- Fig.13................................................................................................................................................page 10- 5.2. Tabulated Conceptual Model......................................................................................................page 11- Fig.14................................................................................................................................................page 11

6. Remediation and Mitigation

- 6.1. The Need for Remediation.........................................................................................................page 12- 6.2. The Environmental Agency Model Proceedures (CLR11)..........................................................page 12- Fig.15................................................................................................................................................page 12- Fig.16................................................................................................................................................page 12- 6.3. Water Remediation.................................................................................................................... page 13- 6.4. Soil Remediation........................................................................................................................page 13- 6.5. Mitigation....................................................................................................................................page 14- 6.6. Case Study: The Whyalla steelworks, Australia.........................................................................page 14

7. Conclusion.................................................................................................................................... page 15

8. Bibliography..................................................................................................................................page 16

1. Introduction

Page 1

1.1. Report aims and Methodology

The intent of this report is to produce a detailed pictorial and tabulated conceptual model of the Croda site. This includes a detailed insight into a selection of potential sources, pathways and receptor linkages which may be present on site; Therefore presenting a selection of considerations essential prior to the granting of any future development.

The methodology for addressing these concerns requires conducting an in-depth site survey and analysis, requiring the assessment of ground conditions and the potential linkages that contaminants may acquire to infiltrate the land.

The results of this survey will inform on relevant mitigation and remediation methods which may effectively approach the specific conditions of the Croda Site.

1.2. Site History

The site first became active as a coal distillation and processing works in the 1870s, involved in the production of coke; a solid carbonaceous material resulting from the destructive distillation of bituminous coal, to be used for furnaces and steel manufacturing. This activity resulted in the production of highly toxic chemicals such as benzene and xylene extracted from the base tar.

In the 1920s the site gained a reputation for its extensive production and large storage tanks, acquiring the name of the Yorkshire Tar Distilleries. During the 1940s creosote was being provided for the preservation of wood and for road construction. By the 1960s the Distilleries had 360 employees.

In 1975 the company was claimed under a new identity as Croda, in which Tar Distillation continued until 1981, where the primary function of the site shifted towards bitumen. With the production of bitumen polymers were added to the product in order to increase flexibility, therefore widening its uses for roofing products, sealants and emulsions.

By the 1990s the profitability of the site had decreased, achieving an average profit of £1 million per annum. In 1998 the site closed, resulting in the redundancy of 45 employees and a demolition process spanning over the next 10 years.

Currently the site is undergoing restoration, which may result in the construction of 381 new homes.

Fig.1.Croda Site: 1985 Aerial Photograph

2. Baseline Information

Page 2

2.1. Site Location

The site is located in the area of Swinton, Rotherham, renowned for its past and current industrial activity which remains active towards the Northern and Southern borders of the site. With this industrial presence there are vast areas of residential housing expanding from the West, divided by a central railway which once supplied the site.

The Eastern border is of great contrast, with an expanse of agricultural fields alongside the adjacent River Don, beyond the South Yorkshire Navigation Canal which runs parallel to the site.

These various receptors have all been directly affected by the various activities which once took place on the Croda site, and will require great consideration in acquiring a successful restoration strategy.

RESIDENTIALCRODA

SITE AGRICULTURAL

RIVER DON

RAILWAY

CANAL

Fig.2. Map of Croda Site and surrounding Context

2.2. Current SIte Conditions

The Croda site can be sub-divided into two zones: The North Zone and The South Zone. When development of the tar distillation plant first ensued it was mostly concentrated within the Southern portion of the site, until the 1940s when activity expanded north for the use of waste disposal. 2.3. Topography

The site is situated 18 metres above sea level, on land which is predominantly flat with minor steepening towards the south-west. This level topography is potentially a result of modification through the introduction of fill materials, therefore making the site more ideal for building construction. The surrounding context is relatively flat, but with greater undulation.

2.4. Geological Conditions

The solid base geology underlying the site is predominantly made up of Upper Carboniferous middle coal measures; a sequence of marine and non-marine strata, such as layered siltstone, mudstone and coal ranging from 15-1,500 metres in depth. The underlying Coal Measures outcrop at the surface as weathered sandstones and mudstones, considered by the Environment Agency to represent a minor aquifer of variable permeability.

An overlying layer of Alluvium deposits covers the site, consisting of 1-5m depth of sands and gravels. This is considered by the Environmental Agency to be a Minor Aquifer of variable permeability. Groundwater has been identified beneath the site predominantly within the alluvial deposits at a depth of approximately 4.5 m below ground level.

The uppermost ground conditions consist of between 0.5-2m depths of Made Ground; a composition of silt, sand, gravel and post-demolition rubble. The Environmental Agency considers Made Ground to be a Non-Aquifer.

NORTHZONE

SOUTHZONE

Fig.3. Croda Site North and South Zones

2.5. Built Form

A majority of the buildings have been demolished, but many structures such as the canal bridge and canal side still remain. In various areas of the site remain underground foundations, basements and tanks. The central pathway leading from the railway bridge to the canal currently remains, for the use of vehicles entering and leaving the restoration site. A fence has been established along the site boundary along the canal, acting as a temporary means for discouraging pedestrians walking along the canal pathway from entering the contaminated land.

2.6. Vegetation

As a result of greater intensity of activity being focused in the south a majority of Vegetation has established in the upper northern portion of the site; mostly composing of small pioneering trees and dense shrub species, which began to thrive post-demolition. Most vegetation was cleared during the beginning of the site restoration, but vegetation alongside the railway line on the western border and along the canal on the eastern border still remains.

3. Conceptual Site Model

Page 5

3.1. Conceptual Site Model (CSM) Definition

A CSM is a primary planning tool for assisting the decision making process for acquiring a successful restoration strategy. This is achieved through the organisation of site information gathered from site analysis into an integrated and clear graphical format; thus enabling an in-depth and holistic understanding of the site's unique characteristics, to determine the site's Contamination status and inform on the decision process.

The CSM takes into consideration:

- What receptors might be exposed- How/why contaminants are present- Whether contaminants are migrating/degrading- What risk/reduction strategies are most feasible

Once established, the CSM can be used to:

- Support the development of a framework for conducting and scoping a site cleanup- Establish a detailed description of the current site setting to form a hypothesis about the fate of contaminants on the site- Potential chemicals of concern and effected media (soil, groundwater, surface water etc)- Evaluate potential restoration options

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Page 7

Contaminant Contaminant Details Location and Source Potential Threats Further Comments

Arsenic

A metalloid usually occurs in

conjunction with sulfur and metals,

rarely as a pure crystal. Main use in

industry is for strengthening alloys of copper and lead.

Also used for pesticides and treating wood

products.

In made ground, shallow

groundwater, waste disposal tips, along

railway and transport lines

Toxic. Carcinogenic. Risk through

dermal contact, ingestion and

inhalation.May reduce plant growth and

contaminate vegetables

The World Health Organisation

standards consider any

concentration above 10 ppb to

be hazardous

Lead

A malleable heavy metal, Used for

building construction and

lead-acid batteries


groundwater, waste disposal tips, along

railway and transport lines

Toxic, A poisonous

neurotoxin at certain contact degrees. Risk

through inhalation

and ingestion. Water pollutant.

Phytotoxic. Uptake

may result in food

contamination.

Related to damage to the nervous

system, resulting in brain and blood

disorders

Copper

A ductile and malleable metal,

with very high thermal and

electrical conductivity. Used for 10,000 years,

now used for electrical wires,

roofing, plumbing and industrial

machinery


groundwater, waste disposal tip

Toxic only at elevated levels.

Water pollutant. List II substance.

Highly phytotoxic.

Chronic copper toxicity does not

occur often in humans, so pose

little threat

4.1. Heavy MetalsFig.5. Heavy Metals Table


Page 8

4.2. Volatile Organic Compounds (VOC’s)


Benzene

An Organic Chemical

Compound of 6 carbon and 6

hydrogen atoms, making it a

Hydrocarbon. A natural constituent of Crude Oil, a by-

product of coke production

Will be mostly concentrated in areas of

the site were coke production took place, and

transfer pumping areas. Contamination of Shallow

Groundwater beneath made-ground. Floats on

water, so spread by surface run-off and into the canal.

Present in Perch Water, made ground and

underground storage tanks.

Toxic. Principal risk through inhalation. Phytotoxic

Colourless and highly flammable liquid. Considered to be

carcinogenic for both humans and animals

Ethylbenzene an organic

hydrocarbon compound


the site were coke production took place, and

transfer pumping areas. Floats on water, so spread by surface run-off and into the canal. Present in Perch Water, made ground and

underground storage tanks

Toxic. Principal risk through inhalation. Phytotoxic

Colourless and a highly flammable

liquid. However the acute toxicity is low. Long-term exposure is considered safe,

but can cause dizziness and throat sensitivityA possible

carcinogen, but currently little

evidence

Xylene

a hydrocarbon consisting of a

benzene molecule with two methyl

substituents. Used as a solvent and clearing agent.

Manufactured by coal carbonisation

for coke production


the site were coke production took place, and transfer pumping areas. In

Shallow groundwater beneath made ground.

Floats on water, so spread by surface run-off and into the canal. Present in Perch Water, made ground and

underground storage tanks

Mildy toxic. Principal

risk through inhalation. Phytotoxic

Highly flammable. Not highly toxic,

however is classed as a moderate hazard

so requires protective clothing

and ventilation

Fig.6. Volatile Organic Compounds Table

* This group is often referred to as BTEX compounds. These elevated levels of aromatic hydrocarbons originate from industrial processes such as coatings, printing works manufacture, engineering works, gas works, oil refineries and solvent recovery works.


Page 9

4.3. Asbestos


Asbestos

A naturally occuring silicate mineral, thin

fibrous crystals. Popular insulation product in the late

19th century for tensile strenght,

sound absorption and resistance to

fire.

Present in made ground/top soil layer

due to building demolition. Also present in waste disposal areas.

Toxic. Carcinogenic. Principal risk

through inhalation.

Prolonged inhalation of

asbestos fibres is highly linked to

the development of lung cancer and

asbestosis, resulting in its

banned use and extraction in the

EU

Fig.8 and 9. Waste present on-site, suspected to be contaminated with the presence of Asbestos

Fig.10 and 11. Water Purifying Ineceptor Tanks

Fig.7. Asbestos Table


Page 10

5.1. Potential Pathways and Receptors

Potential Pathway Potential Receptor Comments

Surface Water Maintenance workers,

Trespassers, vegetation, wildlife

Exposure through short-term contact on-site

Dust - Vapour Inhalation Maintenance workers, Local Residents, Trespassers, wildlife

Exposure on and around the site through aerobic respiration

Ingestion Maintenance workers, Local Residents, Trespassers, wildlife Exposure only from on-site contact

Dermal Contact Maintenance Workers, Trespassers, wildlife Exposure only from on-site contact

Drains Sewage works Contaminants may migrate

through pipes and affect a wider area of residents

Migration through soil/groundwater

Aquatic life in the River and Canal, Residents off-site

through contaminated pipes

Migrating through surface run-off and groundwater. May affect

crops due to soil contamination, harming residents. River and canal

may transport contaminants to great distances

Receptor Direct Pathways Indirect Pathways

People (Human Health) and Animals

Direct Contact, Dermal Absorption, soil injection

Inhalation of dust/vapours, ingestion of

water/vegetables, migration of hazardous gases/vapours

via permeable strata

Controlled Waters Spillage/loss/run off to water body

Migration via permeable unsaturated strata, run-off

via drainage/sewers

Buildings and Structures Direct contact with contaminated soils

Migration of hazardous gases/vapours via permeable strata

Fig.12. Direct and In-direct Pathways

Fig.13. Potential Site Pathways and Receptors


Page 11

5.2. Tabulated Conceptual Model

Receptors/Pathways VOC's (Benzene, Ethylbenzene,

xylene)

Heavy Metals (Arsenic, lead,

copper) Asbestos Comments

Human Health Dermal Contact VOC's may become

toxic vapours if set alight by

trespassers. Ingestion of soil

and dust may transport heavy

metals and asbestos. VOC's

and Heavy Metals may cause harm in

ingested water, however asbestos

is not water soluble

Dust Inhalation

Vapour Inhalation

Ingestion of Contaminated water

Waters Surface Water Depending on

water and soil pH levels, Heavy

Metals may be water soluble. Xylene is highly

mobile in ground and surface water. However asbestos may not travel this

way

Drains

Buildings

Direct Contact with Rubble/Foundations

Disturbance of rubble may release Asbestos into the air with the threat

of inhalation

Fig.14. Tabulated Conceptual Model


Page 12

High riskHarm is likely to arise to a designated receptor from an identified hazard at the site withoutremediation action. Realisation of the risk is likely to present a substantial liability to the siteowner/or occupier. Investigation is required as a matter of urgency to clarify the risk. Remediation works may be necessary in the short-term and are likely over the longer term.

6.2. The Environment Agency Model Procedures (CLR11)

a framework in which the assessment of all sites of land affected by contamination should be carried out. In

accordance with their site assessment criteria, the Croda site has been identified as a ‘High Risk’ area.

6.1. The Need for Remediation

The site is currently undergoing a planning application for remediation and subsequent housing development. Remediation of brownfield land previously used for industrial processes which may potentially pose significant risks to the health of the public is essential. Therefor an efficient and thorough remediation strategy must be arranged to ensure these threats are minimalized.

The Government’s ‘suitable for use’ planning policy, with respect to land affected by historic contamination:

• Ensures land is suitable for its current use;• Ensures land is made suitable for planned future use(s); and• Limits the scope of remediation to that necessary to mitigate unacceptable risks.

The adoption of this policy ensures suitable resolution of the various environmental, social and economic needs with respect to the contaminants on site.

Fig.16. Scale of Risk Assessment Table

Fig.15. Proposed Housing Development on the Croda Site


Page 13

6.3. Water Remediation

6.4. Soil Remediation

• Pump and Treat: Involves the pumping out of contaminated groundwater through a submersible vacuum, extracting/absorbing contaminants and thus purifying the groundwater. However this method is provides only a short-term solution and therefore may not be considered suitable for the site post-development.

• Reedbeds: May provide a more naturalistic and long-term sustainable solution for removing contaminants entering the canal and river. This may also enhance the ecological and social value of the site post-development.

• Permeable Reactive Barriers (PRB): A method acquiring a swell-able, organically-modified silica injected underground in situ. This establishes a permanent soft barrier in the ground, which groundwater filters through and the silica material absorbs contaminants. However this is considered to be a costly procedure so must only be used in extreme circumstances.

• Air sparging: Involves blowing air directly into the ground water, forming bubbles which rise along with the contaminants. The contaminants are stripped from the groundwater by contact with the air, to be transported into the upper unsaturated zone (soil). In situ Soil Vapour Extraction (Explained in 6.4.) is then implemented to remove harmful vapours.

• In situ Soil Vapour Extraction: Involves the removal of contaminants through cleansing with air or steam, working to separate soil vapours into liquids and gases for further necessary ex situ treatment. This method is quick and highly effective, however it is considered unsustainable and relatively expensive, so must only be considered in high risk circumstances.

• In/Ex situ Capping of Subaqueous wastes: Involves isolating highly contaminated waste from the surrounding environment, through a layer of soil and material, preventing further spread of waste product. This has long-term effects and eliminates high risks of dermal contact, migration through groundwater/surface run-off and deadly VOC vapours.

• Ex situ Waste Disposal: Remaining waste such as building debris containing asbestos, rubble, and excess bitumen must be removed from site and disposed of safely.


Page 14

6.5. Mitigation

The act of Mitigation is to lessen the intensity of negative impacts resulting from a proposal, before development commences. In terms of land remediation this involves the lessening of negative environmental, social/health and visual effects which are a result of land contamination and remediation. For developing an effective and reliable mitigation strategy a number of key components and must be addressed, in order to avoid potential dilemmas. In accordance with the Environmental Agency’s publication ‘Guidance for the Safe Development of Housing on Land Affected by Contamination’ (2008) a mitigation scheme must consider:

• Effectiveness: Is it likely to reach targets and meet standards specified by governmental regulations?

• Practicality: Is it feasible with the available resources at hand?

• Cost-effectiveness: Can it be achieved within a realistic and precise budget?

• Long-term Maintenance: Will it require further monitoring and aftercare? Can it be accommodated effectively within the required budget?

The reed bed waste water treatment system provided a low cost solution, with low maintenance and additives, to the coke oven discharge problems. Furthermore it has also significantly enhanced the environmental value of the site.

As mentioned in Remediation, reedbeds could be a viable option for the Croda site. Not only will they aid in the removal of harmful contaminants in soil and water but also bring multiple benefits both environmentally and socially. With this in mind, reedbeds along the river and canal could be ideal as a mitigation solution in the likely case of housing development going ahead on site.

6.6. Case Study: The Whyalla steelworks, Australia

The Llanwern plant at Whyalla represented the first reed bed technology trial on coke oven effluent. Through a soil-based reed bed system, the effluent is cleansed through the biologically active soil and roots of an expanse of reeds, and then drains through a pipe at the base of the bed.

After successful trials a large scale system was constructed and commissioned in 1997. This system involved the adaptation of the plants and biological life within the system to pollutants in the wastewater.

7. Conclusion

Page 15

Throughout this report a variety of potential risks and effects have been identified, being assessed for their potential severity in the likely situation of future housing development.

• Phase 1: the process and activities involved in hazard identification and assessment;

• Phase 2: the process and activities involved in risk estimation and evaluation;

• Phase 3: the process and activities involved in remediation; design, implementationand verification.

A series of effective remediation and mitigation tactics have been suggested and analysed, to ensure that potential threats are minimised to meet satisfactory standards set by Governmental objectives and Environmental Agency guidance.

Nonetheless the problem does not stop with remediation as further maintenance, upkeep and management is required to ensure the safety of human health and local ecology.

Through meeting all of these objectives, the fate of the site can be successfully safeguarded, and thus ensuring a positive and prosperous future for the Croda site.

8. Bibliography

Page 16

Online PDF

Harrison, A. (2008) THE LAND REMEDIATION YEARBOOK 2008: A GUIDE TO GUIDANCE. [e-book] the Environmental Industries Commission. http://www.eic-yearbook.co.uk/docs/doc_022_guide.pdf [Accessed: 14/04/2013].

Unknown. (2008) Guidance for the Safe Development of Housing on Land Affected by Contamina-tion R&D66: 2008 Volume 1. [e-book] NHBC and Environment Agency. http://a0768b4a8a31e106d8b0-50dc802554eb38a24458b98ff72d550b.r19.cf3.rackcdn.com/sr-dpub66-e-e.pdf [Accessed: 10/04/2013].

Unknown. (2007) Swinton Former Croda Bitumen Works: Draft Canal Impact Assessment Report. [e-book] Leeds: Woodford Group. http://roam.rotherham.gov.uk/PlanNet/documentstore%5CROUP%20CANAL%20IMPACT%20ASSESS_01_1.PDF [Accessed: 12/04/2013].

Unknown. (2011) PROPOSED DEVELOPMENT AT FORMER CRODA BITUMEN WORKS CARLISLE STREET SWINTON, ROTHERHAM PLANNING APPLICATION BY GLEESON HOMES & REGEN-ERATION TRANSPORT ASSESSMENT. [e-book] Rotherham: http://roam.rotherham.gov.uk/PlanNet/documentstore%5CTRANSPORT%20ASSESSMENT_01_1.PDF [Accessed: 05/04/2013].

Unknown. (2013) Solidification of contaminated sewage sludge - Luggie Glen. [e-book] UK Spill Contractors. http://www.soilutions.co.uk/wp-content/themes/thesis/custom/media/Case_Study_Soilutions_North_Lanarkshire.pdf [Accessed: 12/04/2013].

Websites

Geoinc.org (2008) Soil Vapor Extraction (SVE) and C3 Technology the Low Cost Soil Remediation Solution. [on-line] Available at: http://www.geoinc.org/soil_vapor_extraction.php [Accessed: 16 Apr 2013].

Mecx.net (n.d.) In-Situ Chemical Oxidation (ISCO) | Remediation Services | MECX. [online] Available at: http://mecx.net/links/in-situ_chemical_oxidation.html [Accessed: 16 Apr 2013].

Images

Fig.8. Waste present on-site, suspected to be contaminated with the presence of Asbestos (Image) Swinton Former Croda Bitumen Works: Draft Canal Impact Assessment Report. [e-book] Leeds: Woodford Group. http://roam.rotherham.gov.uk/PlanNet/documentstore%5CROUP%20CANAL%20IMPACT%20ASSESS_01_1.PDF [Ac-cessed: 12/04/2013].

Fig.9. Waste present on-site, suspected to be contaminated with the presence of Asbestos (Image) Swinton Former Croda Bitumen Works: Draft Canal Impact Assessment Report. [e-book] Leeds: Woodford Group. http://roam.rotherham.gov.uk/PlanNet/documentstore%5CROUP%20CANAL%20IMPACT%20ASSESS_01_1.PDF [Ac-cessed: 12/04/2013].

Fig.10. Water Purifying Ineceptor Tanks (Image) Swinton Former Croda Bitumen Works: Draft Ca-nal Impact Assessment Report. [e-book] Leeds: Woodford Group. http://roam.rotherham.gov.uk/PlanNet/documentstore%5CROUP%20CANAL%20IMPACT%20ASSESS_01_1.PDF [Accessed: 12/04/2013].

Fig.11. Water Purifying Ineceptor Tanks (Image) Swinton Former Croda Bitumen Works: Draft Canal Im-pact Assessment Report. [e-book] Leeds: Woodford Group. http://roam.rotherham.gov.uk/PlanNet/documentstore%5CROUP%20CANAL%20IMPACT%20ASSESS_01_1.PDF [Accessed: 12/04/2013].

Fig.15. Proposed Housing Development on the Croda Site (Image) Unknown. (2011) PROPOSED DEVELOP-MENT AT FORMER CRODA BITUMEN WORKS CARLISLE STREET SWINTON, ROTHERHAM PLANNING APPLICATION BY GLEESON HOMES & REGENERATION TRANSPORT ASSESSMENT. [e-book] Rotherham: http://roam.rotherham.gov.uk/PlanNet/documentstore%5CTRANSPORT%20ASSESSMENT_01_1.PDF [Ac-cessed: 05/04/2013].

land contamination, restoration and revegetation report- croda site

Documents

croda site

site history

site location

list of site contaminants

current site conditions

geological conditions

contamination reporta

potential sources