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Risk Assessment Contaminated Land
Objectives to know the characteristics of soil and chemical contaminants affecting risk assessments of contaminated land. to know the practical steps involved in identifying and quantifying the pollutant hazards to know the risk assessment tools and frameworks used to manage contaminated land References Nathanail, Paul.: Reclamation of contaminated land / Paul Nathanail, Colin Ferguson and Paul Bardos 2003 BURA Breaking old ground: BURA guide to contaminated land assessment and development Petts, Judith. Risk-based contaminated land investigation and assessment 1999 Nathanail, C. P Introduction to contaminated land management 1999 Risk assessment for contaminated sites in Europe Nottingham : LQM Press, 1998 Vol. 1. Scientific basis -- Vol. 2. Policy frameworks RIS Cairney, T. The re-use of contaminated land : 1995 Environment Agency and DEFRA Websites –
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Risk Management of Contaminated Land
Course Structure Introduction Subsurface Characteristics - Soils and Contaminants Site Investigation (Hazard Assessment) Interpretation of data (Risk Assessment) Regulatory Frameworks (Risk Management) Remediation (Risk Management)
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The Contaminated Land Legacy
Parliamentary Office of Science and Technology 1993 Expert Estimates:- 50,000 to 100,000 potentially contaminated sites in UK 100,000 to 300,000 hectares (significantly less which pose risk to human health)
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Potentially Contaminating Industries
Landfill and other waste disposal sites. Gas works, coal-carbonization plants and ancillary by-product works. Sewage works and farms. Scrapyards. Railway land, especially large sidings, depots and breaking yards. Roads, airports and abandoned wartime airfields. Docks, canals and abandoned or infilled port ancillaries, shipbreaking yards. Oil refineries, petroleum storage and distribution sites. Metal mines,, foundries, steelworks, metal finishing works. Mineral extraction sites not yet infilled (quarries, coal) Glass works. Chemical works. Munitions production and testing sites, wartime installations. Asbestos works and building incorporating asbestos. Tanneries and fellmongeries. Paper and printing works. Industries making or using wood preservatives, herbicides and pesticides. Cotton and other textile mills and bleach works. Metal plating works and yards. Brickworks, potteries and ceramic works. Nuclear power stations, radioactive storage/disposal installations.
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Law & Legislation Common Law (Civil Law) case law, not specific to CL
Statutory Law new regulations specific to CL
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Common Law (Civil liability )
Law of Tort (breach of legal duty) i.e. Case Law Rylands v. Fletcher 1866 A person bringing a dangerous item or substance onto his own land does so at their own risk strictly liable for the consequences of any escape onto another’s land substance must be ‘unnatural’ or ‘unnaturally there’ damage must be reasonably foreseeable conduct of the defendant is irrelevant Trespass direct, unauthorised interference with another’s property could cover spillage or deposit of pollutants not yet tested in the courts
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Common Law (Civil liability )
Negligence fault based - failure to take care in situations in which damage is reasonably foreseeable “care” extends to ‘future users’ liability is variable depending on the amount of care taken does not cover purely economic losses Nuisance (interpretation of degree of harm) activity that interferes with another’s enjoyment of land On-going interference - can obtain an injunction Concluded interference - can obtain damages foreseeable “omission to do what a reasonable person would do” Time Limit - 6 Years (begins from time of discovery)
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Cambridge Water (CW) v. Eastern Counties Leather (ECL) Ltd
Perchloroethylene solvent escaped from tannery Contamination of groundwater Water company failed new EC standards 1. CW failed in High Court case of negligence, nuisance, Rylands v. Fletcher dismissed as tanning was not unnatural 2. Prosecution upheld in Court of Appeal ECL deemed liable, £1m damages (focused on Nuisance) 3. House of Lords Decision (in favour of ECL) reversed the Court of Appeal decision no liability under Rylands v. Fletcher as “not foreseeable”
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Contaminated land - Disasters
Love Canal, USA (1978) Hooker Chemical Company Building in 1950’s (despite caveat in deeds) illness, genetic disorders, residents evacuated Lekkerkerk, Netherlands (1978) building on reclaimed site 1600 illegally dumped drums drinking water polluted, residents evacuated Eastern Counties Leather vs Cambridge Water Co (UK 1993)
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Nature of the Pollution
Some important factors which determine the fate of chemicals in soil. Organic or Inorganic Charge (ions) Volatility, Molecular weight Solubility, Hydrophilic character Functional Groups, affects solubility (polar character) Hydrophobic character, interaction with soil colloids Quantity or Concentration Toxicity and Biodegradability Density (Specific Gravity), Viscosity
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Soil Structure and Hydrology
Soil Depth and Horizons Organic Matter content Plant Residues Humic Acids, Fulvic Acids, Humin. Particle size distribution Sand, Silt and Clay Fractions Soil Permeability Groundwater, Water-table Vadose (unsaturated) zone saturated zone
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Movement in the Soil Liquids Vapours Gravity Advection Diffusion
vertical movement until sorption by soil matrix dominates. LNAPL - as far as Capillary Zone or Water Table DNAPL - through water table, stops at Impermeable Layer Advection transported by the flow of the bulk liquid (water) if dissolved Vapours Diffusion random molecular movement transported by bulk flow of soil vapour
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Movement of Contaminants within an Aquifer
Spill Spill Soil Surface Spill Vadose Zone LNAPL Capillary Zone DNAPL Saturated Zone (Aquifer) Plume of soluble components
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Potential Outcomes for Contamination in Soil
Hazard stays fixed in soil matrix = MINIMAL RISK Hazard stays fixed in soil matrix but site has receptors = RISK Hazard moves into groundwater and is transported towards receptor. = RISK Dust and Volatilisation give rise to subsequent Air Contamination = RISK Which Are relevant to the site? REMEDIATION eliminates or minimises RISKS
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Typical effects of Hazards
Toxicity to Human Health Uptake of contaminants by crops Ingestion Inhalation Skin Contact Contamination of water resources (Groundwater) Toxicity to Ecosystems / Wildlife Fire and Explosion Chemical attack on buildings, materials and property
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Risk Management For a contamination to present a risk there must be:
a potentially harmful Source a Pathway along which the contaminant can travel. a Receptor a plausible Pollution Linkage. SOURCE RECEPTOR PATHWAY
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Technical Approach to Risk Management of Contaminated Land
What are the key stages in the process? Identify and assess Hazards Collection of Data Conceptual model (source-pathway-receptor linkages) Evaluate and Quantify Risks posed by Hazards Professional judgement Generic Guidelines or screening values Models (site-specific characteristics) Prioritize sites (Local Authority) fair and transparent process Consider consequences of a change in use force remediation of sites with “Risk”
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2. Site Investigation (Hazard Assessment)
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Objectives and Purpose of Site Investigation
Determine Contamination nature, source, distribution, extent acute effects (structures, biota) Geotechnical Information subsurface structures, cables, pipes, drains soil properties, site geology Water Environment groundwater level and composition, local abstraction use site run-off to surface waters
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Preliminary Investigation
Desk Study Current Layout - buildings, drains, process areas, plant, services. Materials - feedstocks, products, wastes History of the site Industrial uses previous incidents Disposal records Geology and Hydrology desk study information obtained from: Maps, photographs, local history, directories, Technical Literature, Local / Government Bodies, residents, workers
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Preliminary Investigation
Site Reconnaissance (Site Walkover) External observation of acute hazards (ruptured tanks, etc) Visual inspection for Contamination discoloured soil, deposits, odours, gas (detection tubes) vegetation - chlorosis, stress condition of fences, metal structures seepage through river banks, land drains Activities on neighbouring land (on-going) Confirms Desk Study details (e.g buildings / services/ etc) Produce Photographic Evidence Planning of Subsequent Investigations Best estimation of the extent of contamination on the site
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Exploratory Investigation
Confirms presence of contamination where the Preliminary Investigation is inconclusive neither investigation can prove the Absence of contamination Informed sampling locations Sampling locations can form Stage 1 of the Main Investigation Composite samples Soil profile samples (depth) Restricted range of chemical analysis (targeted e.g. BTEX) helps with Planning of the Main Investigation
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Main Investigation Planning Site Access Safety Procedures
clothing, respiratory, hygiene, confined space. sample labelling, transport Accident Procedure, First Aid. Environmental Protection dust suppression, Wheel wash, decontamination Data Requirements specific requirements of Regulatory bodies sampling and analysis strategy Long Term monitoring Requirements
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Main Investigation - Sampling Strategy
Requirements to be addressed: Nature of sample air, water, soil Sample Type and Size spot, or composite (mixed) Collection and Storage containers, temperatures Method of sampling surface augering Trial pits and trenches Boreholes - soil, water, gas Depth Pattern and Frequency of sampling
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Main Investigation - Sampling Strategy
Grid Size Site Size Grid Size (hectares) (m) Number Site Size Number (hectares) of Samples
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Main Investigation - Chemical Analysis
Quality Assurance NAMAS National Measurements Accreditation Service Accuracy Submit a prepared control sample (known value) Scope Specific Analysis based on Exploratory Investigation or Desk Study Standard Suites pH Phenols Toluene extractable Matter (TEM) coal tars mineral oils PAH, PCB, BTEX Cd B Pb Hg As Cr Zn Chloride Sulphate Sulphide Cyanide sulphur
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Main Investigation - Gas Analysis
In-Ground Gases methane, hydrogen sulphide VOC On-site Methods Geophysical (conductivity/magnetic field) Remote Imaging (IR for methane) Spot Sampling Portable Instruments (GC, IR) Detection Tubes (Drager) Laboratory Analysis sample collection (Tedlar bags) standard analytical equipment
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3. Interpretation of Contamination Data
(Risk Assessment)
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Technical Approach to Risk Management of Contaminated Land
What are the key stages in the process? Identify and assess Hazards Collection of Data Conceptual model (source-pathway-receptor linkages) Evaluate and Quantify Risks posed by Hazards Professional judgement Generic Guidelines or screening values Models (site-specific characteristics) Prioritize sites (Local Authority) fair and transparent process Consider consequences of a change in use force remediation of sites with “Risk”
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Tiered “Risk Assessment Framework”
Risk screening or Preliminary Risk Assessment Desk study information Tier 2 Generic Quantitative Risk Assessment Uses Generic Assessment Criteria (GAC) i.e. SGV for “typical standard site” Tier 3 Detailed Quantitative Risk Assessment requires modelling tools (CLEA)
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Guidelines and Standards
system of fixed, legally binding values (not particularly relevant to the soil situation. Why?) Soil Guideline Values ICRCL (Interdepartmental Committee on the Redevelopment of Contaminated Land) BRE (Building Research Establishment) Dutch Intervention and Target Values New UK CLEA derived SGVs
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Soil Guideline Values (SGV)
Different “typical land uses” defined Residential (with and without vegetable growing) allotments Commercial / industrial Certain circumstances are not covered by SGVs and require Tier 3 risk assessment (i.e. CLEA modeling) Playing fields Schools Complete cover by hardstanding
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Guidelines ICRCL 58/93 Threshold 250 50 1000 Action 5000 no limit 500
10,000 Trigger Values (mg/kg air-dried soil) Contaminant Complex Cyanides PAH Proposed Uses Domestic gardens, allotments Landscaped Areas Buildings, hard cover Domestic gardens, allotments, play areas Landscaped areas, buildings, hard cover
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Guidelines Examples of SGV (CLEA)
Standard Land Use Cadmium (mg/kg) Mercury Arsenic Residential (with plant uptake) 130 8 20 Residential (without plant uptake) 200 15 Allotments Commercial 5000 480 500
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Toxicological Data TOX Reports (use in CLEA model)
Arsenic, Benzo(a)pyrene, Cadmium, Chromium, Inorganic CN, Lead, Mercury, Nickel, Phenol, Selenium, Dioxins, PCB, Benzene, Toluene, Ethyl Benzene, Xylene, Vinyl chloride, tetrachloroethane, 1,1,1, trichloroethane, 1,2dichloroethane, tetrachloromethane, Naphthalene, PAH. Soil Guideline Value Reports (set the SGV) Arsenic, Cadmium, Chromium, Inorganic Mercury, Nickel, Selenium, Lead, Benzo(a)pyrene, Benzene, Ethylbenzene, Toluene, Xylene, Phenol, Naphthalene.
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SGV (from CLEA) SGV assume a standard site defaults conditions for:
Receptor behaviour Age, weight height, skin area Exposure frequency, soil ingestion rate, vegetable consumption rate, time on site Land Use Residential, Allotment, Commercial/Industrial Depth of Soil 0.5m for ingestion 0.5m for plant uptake 0 – 0.1 m for dust inhalation 1m for vapour inhalation
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Quantitative Risk Assessment
Human Health CLEA Model (Contaminated Land Exposure Assessment) RISC-HUMAN (C-soil model Netherlands) Groundwater (Dispersion) ConSim Model (Environment Agency) Ecosystems currently excluded wildlife, biodiversity, HC50 research needed
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Human Health Contaminated Land Exposure Assessment (CLEA)
Site Specific Data Chemicals Climate - precipitation, wind Soil Properties physico-chemical, pH particle size distribution permeability organic content Site Use user activity patterns (vegetable consumption) building type Monte Carlo probabilistic model Probability Density Functions (PDF) compare with Tolerable Daily Soil Intake (TDSI)
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Risk to Groundwater ConSim Model (Environment Agency)
Determines whether contaminant is likely to exceed WQS value at several locations in the aquifer Multi-Tiered Approach (i)Leaching - (ii) Migration - (iii) Dispersion/Diffusion Tier (iv) for complex geology Monte Carlo model input data as PDF addresses element of uncertainty decay and biodegradation are calculated output data graphical, probabilities of exceeding WQS
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Unsaturated Zone Retardation
CONTAMINATED SOIL VADOSE ZONE AQUIFER Simulated Leach Data Level 2 Unsaturated Zone Retardation Level 3 Dilution Dispersion Biodegradation Level 1 Theoretical Leach Properties If Concentration < WQS STOP If Concentration < WQS STOP Multi-Tiered Approach of the ConSim Model
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Multi-Tiered Approach of the ConSim Model
Contaminant Level 1 Vadose Zone Level 2 Saturated Zone Level 3
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Assumptions for Guidelines and Models
Validity of analytical data sample errors, heterogeneity of contamination Toxicological and Ecotoxicological Reference Dose databases incomplete Predicted No Effect Concentration (PNEC) Maximum Permissible Risk Concentration (MPC) Tolerable Daily Intake (TDI) Negligible Risk Concentration (NC) Lowest (& No) Observable Effect Concentration (LOEC, NOEC) Reference Dose (USEPA for carcinogens) Uncertainties contaminant transfer, uptake, availability, synergistic effect, metabolic detoxification, receptor behavior, soil properties (adhesion), dermal resorption data, average values representing statistical distributions of the exposure factors.
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4. Regulatory Frameworks
(Risk Management)
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Technical Approach to Risk Management of Contaminated Land
What are the key stages in the process? Identify and assess Hazards Collection of Data Conceptual model (source-pathway-receptor linkages) Evaluate and Quantify Risks posed by Hazards Professional judgement Generic Guidelines or screening values Models (site-specific characteristics) Prioritize sites (Local Authority) fair and transparent process Consider consequences of a change in use force remediation of sites with “Risk”
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History of Contaminated Land Policy
USA CERCLA 1980 (SUPERFUND) SARA 1986 Netherlands Soil Clean-up Act 1982 policy reversal 1987 UK ICRCL (guidance) EPA (STATUTORY LAW) 1993 “consultation” EA (STATUTORY LAW) PPC Regulations (2000) (STATUTORY LAW)
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Framework Policy Objectives
Prevent new contamination Deal with unacceptable risks to human health and the environment (Environmental) Bring contaminated land back into beneficial use (Economic) to limit cost burdens to proportionate, manageable and economically sustainable levels (Social) (Sustainable Development)
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Contaminated Land Regime
Environment Act 1995 Section 57 (EA 1995) inserts Part IIA into the Environmental Protection Act 1990 Local Authority responsible LA to formulate Strategy by mid-2002 LA actively identify contaminated sites & cause them to be remediated
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Definition of Contaminated land
“Contaminated land is any land which appears to the regulatory authority, by reason of substances in, on or under the land, that: a) significant harm is being caused or there is a significant possibility of such harm being caused; or b) pollution of controlled water is being, or is likely to be caused” (Environment Act 1995) “harm to the health of living organisms or other interference with the ecological systems of which they form part, and in the case of man, includes {harm to} his property”.
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EA 1995 Enforcement Responsibilities Duties Tasks
Cause their area to be inspected to identify Contaminated Land To determine whether a particular site is “contaminated” To Act as enforcing authority for contaminated sites (other than Special Sites) Establish responsibility for remediation. Determine what remediation is required and to ensure that it takes place. Arbitrate on the who bears what proportion of consequent liability. Record and maintain prescribed information in a Public Register.
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Section 108 Environment Act 1995 :-
Powers of Inspectors Section 108 Environment Act 1995 :- enter at any reasonable time make any examination or investigation necessary take photographs or samples require the giving of information order that premises or parts be left undisturbed
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EA 1995 Information and Inspection
L.A’s may derive information form a number of sources to enable an assessment to be made Other Statutory Bodies Its own Land Use records Public Complaint Land Owners
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Prioritisation/Categorisation
Part I Assessment Preliminary prioritisation of sites into groups for Part II Assessment under the following headings. Development Surface Waters Groundwater (This will comprise a desk top study and can be carried out by non- specialist personnel) Part II Assessment Sites in each group will be categorised using individual risk assessment Priority given first to “Development Group A” Site information examined Site Visit Establish contaminants, pathway and risk Detailed exploratory survey where indicated (Expert help will be required)
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Part I Assessment GROUP A GROUP B GROUP C
Residential development, school playground or allotment within 50 m YES Not Known GROUP A NO YES Not Known Industrial, commercial development within 50 m or residential within 250 m GROUP B NO YES Not Known Site in agricultural or amenity use including Parks and playgrounds GROUP C NO
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CLASS “A” CLASS “B” Any person who causes or knowingly
Appropriate Person CLASS “A” Any person who causes or knowingly permitted contaminating substances to be IN, ON or UNDER the site CLASS “B” Where reasonable enquiry has failed to identify a person fitting the definition of “Class A”, the owner or occupier of the land If no Class A or Class B then site is an Orphan Site (ownership passes to LA)
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Appropriate Persons - Exclusions
Class A – for abandoned mines Class B - where pollution is to controlled water Class B – for contaminants escaping to adjacent land Class B - when they act in official capacity e.g. ‘insolvency practitioners’, ‘official receiver’ Class A – where land was sold with ‘information’ regarding level of contamination
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Apportionment of Liability Inherited Problems
Adjoining Land Contaminated land X migration Y “Person A” causes contamination of “Contaminated Land X” Innocent “Person B” becomes owner/occupier of “Contaminated Land X” “Person B” not liable to remediate “Adjoining Land Y” unless they had knowledge of the contamination at purchase (Caveat emptor) Contaminant
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Special Sites Environment Agency becomes the enforcing authority after LA designates a site as a Special Site on the basis of: Water Pollution Cases Controlled water used for Drinking Water abstraction Ecologically important sites (SSSI, reserves) Major Aquifers Industrial Cases Pollution from sites involving Acid tar, Oil, Explosives, and Nuclear (excludes coal processing) Defence Cases Army, Navy, Airforce, Weapons Testing sites Extends to contaminated sites adjacent to above cases
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EA 1995 Remediation Notices
Where Pollution Linkage is confirmed Remediation Notice served on each “appropriate person” Can cover assessing site condition (detailed intrusive Site Investigation), preventative works, remediation and monitoring Must be “reasonable” having regard to cost and seriousness of harm/pollution Must be preceded by consultation (an opportunity for voluntary action)
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Attributing Costs for Remediation Actions
Single-Linkage Action Shared-Action (when more than than one pollution-linkage) Single Liability Group Multiple Liability Groups Complex Variable Attribution of Responsibility. The costs may be shared: Equally In proportion to capital assets in the land (multiple Group B) In proportion to costs relating the contamination caused be each member (multiple Group A) As the enforcing authority sees as just and fair
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Non-Compliance with Remediation Notice
Enforcing Authority can carry out the remediation and recover costs. Non-compliance is a criminal offence, punishable by imposition of a fine of up to £20,000 plus £2,000 a day.
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Recovery of Costs Local Authorities must take into account: HARDSHIP LA must consider any hardship that may be caused. BUSINESS CLOSURE OR INSOLVENCY Where remediation costs would make a business insolvent, the authority should consider a reduction in costs. The main aim is to recover as much cost as possible without causing insolvency.
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EA 1995 Public Registers Will be maintained to include: Remediation notices and appeals. Remediation work carried out following a remediation notice. Conviction for offences.
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EA 1995 Conclusion CL Regime brought into force 2000. Local Authorities published Strategy 2002 New regime extremely complex and bureaucratic Lack of significant new resources Responsibility for “orphan sites”
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Pollution Prevention & Control (PPC) Regulations 2000
IPPC Directive (96/61/EC) enacted in UK as “The Pollution Prevention and Control (England and Wales) Regulations 2000” Contaminated land covered under requirements for ‘Site Reports’ Regulator is ‘Environment Agency’
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Pollution Prevention & Control (PPC) Regulations 2000
Principle of PPC Specific Industrial Sectors are regulated Aim to preserve land quality rather than deal with Historic pollution (I.e. stop future pollution) Linked to Permit Application authorises the site (or installation) to conduct specified industrial activity Process requires ‘Site Report’ a detailed investigation of current state of the land that acts as a ‘baseline’ Closure of Site (or Change of Use) Cessation Site Report compared with Original Site Report Site must be remediated to ORIGINAL CONDITION and not ‘Suitable for use’
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Pollution Prevention & Control (PPC) Regulations 2000
Purpose of a Site Report To document the condition of the site with particular reference to substances in, on or under the land that may constitute a pollution risk All land of the installation is covered Phased approach 1a Desk Study (Conceptual Model) 1b Further Desk Study and Exploratory Investigations 2 Main Intrusive Investigation Complex activities may be zoned Technical Content presentation of lateral and vertical distribution of contaminants Site Report sent to LA (as statutory consultee) Data can be used by LA under Part IIA EA 1995 legislation
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5. Site Remediation (Risk Management)
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Risk Management Remediation Strategy
Source permanent reduction of risks numerous technical approaches Pathway risks managed in short to medium term several different engineering approaches Target not usually applicable or practicable
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Remediation of Contaminant Source
Removal excavation and landfill (dig and dump) Degradation Bioremediation, Chemical and Thermal destruction Natural Attenuation Extraction Soil washing, Vapour Extraction
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Remediation - Contaminant Pathway
Engineering Methods In-ground Barriers Surface Covers hard cover vegetation Solidification and Stabilization Groundwater pumping
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Contaminated land Remediation
Multifunctionality Approach always apply highest technical level of clean-up Suitable For Use clean-up level determined by land use favoured approach based on the “risk-environmental benefit” residential with gardens residential without gardens parks and recreational areas agricultural industrial and commercial
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Risk Based Corrective Action (RBCA)
The "formal" definition of RBCA is as follows: “A streamlined approach in which exposure and risk assessment practices are integrated with traditional components of the corrective action process to ensure that appropriate and cost-effective remedies are selected, and that limited resources are properly allocated.” The goals of a RBCA process are: Protection of human health and environment Practical and cost-effective application of risk-based decision-making
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Natural Attenuation Spontaneous process Long Term
mostly biological BTEX half life (chemical =108 yr , biological = <1 yr) Long Term Risk Based Corrective Action (RBCA) Environmental benefit v. Cost may be better to address consequences than to treat the source (e.g. borehole contaminants) Lines of Evidence Primary (concentration v. time, concentration v. distance) Secondary (supportive) (DO level, pH, electron acceptors, active microbes)
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Monitored Natural Attenuation
Not a “Do-Nothing” Option quantify the natural breakdown process Monitor Plume position of the 10 ppm threshold Sentinel well Receptor Monitoring wells flow
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