Sampling, planning, and preliminary assessment of contaminated sites
Module 3
Contents
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Develop basic understanding of the key steps in planning and conducting an oil-contaminated site assessment including development of Conceptual Site Models, sampling design and techniques; understand contaminants of concern, field kits and laboratory analysis, and sample preparation, including brief introduction to standard equipment and procedures associated with Health, Safety & Security (HS&S).
Topics
Reminder: Overall Objectives of a CSA
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Traceability – Representativeness – Trust
Overall: what’s involved?
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Introduction & key Site Assessment steps
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! Key term:
Risk Assessment
= the combined effort of identifying and analyzing potential events that may have severe negative impacts and making judgements "on the tolerability of the risk on the basis of a risk analysis" while considering influencing factors.
Phased Investigation Approach
Phase 1 - Preliminary Site Assessment to determine the potential for site contamination
Phase 2 – To confirm presence/absence of suspected contamination
Phase 3 – To delineate the contamination information (area/depth/types), a requirement for Risk Assessment and Remediation Planning
Can include four phases
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Contaminated Land Surveys
Phase 1 Contaminated Land Survey (aka Phase 1 Desktop Study) and Site Reconnaissance – identifying potential contamination sources, pathways and receptors, to develop the initial Conceptual Site Model (CSM). Phase 1 will determine whether a Phase 2 Intrusive Site Investigation is required.
Phase II Intrusive Site Investigation – Boreholes, sampling, drilling, trial pits, etc. to assess the ground conditions, carry out in situ testing and obtain samples for geotechnical and contamination testing.
Phase III Options Appraisal and Remediation Strategy – If Phase II suggests there is a risk to human health, controlled waters, plants, etc. then a Phase III will be required which will be carried out in consultation with the Local Planning Authority and/or the Environment Agency.
Phase IV Verification (Validation) – Site inspections and providing independent Validation of range of remediation technologies & protection measures including gas and vapour barrier membrane installation, engineered topsoil cover systems, contamination hotspot removal, tank removal, soil waste management and re-use, environmental permit surrender, etc.
Source: https://www.subsurface.co.uk/services/environmental-consultancy/contaminated-land-surveys-and-risk-assessments/
Sources and scale of errors
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Sampling Planning Overview… reminder
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Phase 1 Preliminary Site Assessment
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Preliminary Site Assessment Form
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Main headings
Site specific: Identification, Location (GPS)
Access restriction, Topography
Spill details: Legacy site, Oil spill,
Area, Classification of pollution (soils, air, surface and ground water, damage to vegetation, residences, agriculture)
Adjacent areas details:
Affected flora and fauna, Neighboring land use (N/E/S/W), Residential information (size/ water source), Surface hydrology
Note: Preparations for field visit include health & safety, PPE, maps, equipment (probes, GPS, camera (charged/batteries), forms, pen/paper (spares), sun protection, spades/digger, sample bags, labels).
Preliminary Site Assessment: Reporting
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Table of Contents (based on Headings in Site Assessment Form)
Executive Summary
1. Introduction
1.1. Project Contractual Basis and Personnel Involved
1.2. Background Information
1.3. Project Objectives
1.4. Scope Of Works
2. Source Audit Findings – Production & Operational History
2.1. Current Site Operations
2.2. Previous Site Operations
2.3. Chemicals of Potential Concern
3. Site Environmental Setting
3.1. General Introduction
3.2. Regional Geology and Hydrogeology
3.3. Site Geology and Hydrogeology
3.4. Summary of Previous Site Sampling and Monitoring Data
4. Summary, Conclusions and Recommendations
4.1. Summary AND Conclusions
4.2. Recommended Way Forward
5. References
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Planning process
The planning process (sampling campaign) can be divided into two parts:
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Planning process: Non-scientific part
Non-scientific or “classic project management” part:
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Planning process: Scientific part
Scientific part:
Used to define:
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Preparing the Conceptual Site Model
The conceptual site model contains the following information:
This information is necessary to develop the HYPOTHESIS OF CONTAMINATION
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Template for Conceptual Site Model
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Definition of a Conceptual Site Model
A CSM, “should reflect the best interpretation of available information at any point in time” (US EPA).
A CSM is defined as, “an evolving document that will continuously be revised as additional data is collected. The CSM should be maintained and updated as new information is collected throughout the life cycle of the project” (Interstate Technology & Regulatory Council, 2012).
A CSM attempts to fit known information together in an organized fashion to identify data gaps and additional areas of study or concern (Michigan Department of Environmental Quality).
The usefulness of a CSM is in generating consensus (involving all stakeholders) and assisting with site-closure decisions by depicting a model representative of all data known about a site.
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Simplified Conceptual Site Model
Site investigation and CSM design assess the viability of exposure pathways from contaminant release points to human and environmental receptors.
Source: The Brownfields and Land Revitalization Technology Support Center, December 2008.
Shown above are potential exposure concerns from transport mechanisms including air, soil, and ground-water, which may lead to contaminant concerns with indoor air and drinking water.
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Draft Outline - Conceptual Site Model
Based on the findings from the Preliminary Site Assessment, a draft outline of the CSM is prepared.
In preparing this draft CSM, the team has identified:
Now they must conduct the detailed sampling.
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Some key consideration for CSM
• Nature of contamination – how does this affect pathways?
e.g. Any volatiles? Soluble/mobile in groundwater? Non-aqueous phase liquid (NAPL)?
• Have all plausible s-p-r linkages been identified?
Not just the ones covered by the generic exposure model e.g. off-site migration of groundwater/vapour, diffusion through pipes
• Are there any mitigating circumstances?
e.g. Depth of contamination, vapour barriers
• What changes might occur in the future?
e.g. Change in site levels, hard standing removed
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Site Characterization & Contaminants of Concern
BDA SITE DESIGNATION | DESCRIPTION OF CONTAMINANTS |
GREEN | Substances have little potential to cause significant harm to humans, e.g. sub- and topsoil, hardcore, bricks, stone, concrete, clay, ceramics, wood, paper, plastics, wool, cork, ash, clinker, cement. |
YELLOW | Substances not sufficiently harmful to potentially cause death or injury but nevertheless require protection to be worn. E.g. include waste food, vegetable matter, household waste, garden waste, leather, resins, electrical fittings, soaps, cosmetics, tar pitch, solidified wastes, silica dust. |
RED | All substances that could subject persons to risk of death, injury or impairment of health. Wide range of chemicals e.g. toxic metals and organic compounds, pharmaceutical and veterinary wastes, phenols, medical products, solvents, micro-organisms, asbestos, thiocyanates, cyanides, hydrocarbons, flammable and explosive materials. Materials that are particularly corrosive or carcinogenic |
British Drilling Association (BDA)
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Site Characterization & PPE
| Item | Green | Yellow | Red |
1 | Hard hat | X | X | X |
2 | Gloves and other forms of hand protection | X | X | X |
3 | Eye Protection (as necessary) | X | X | X |
4 | Ear Protection | X | X | X |
5 | Overalls | X | X | X |
6 | Waterproofs (as necessary) | X | X | X |
7 | Industrial Boots with Sole and Toe protection | X | X | X |
8 | High Visibility Clothing | X | X | X |
9 | Fire Extinguisher | X | X | X |
10 | Fire Blanket | X | X | X |
11 | First Aid Kit | X | X | X |
12 | Mobile Telephone (outside contaminated area) | X | X | X |
13 | Clean Water Supply | X | X | X |
14 | Washing Facilities | X | X | X |
15 | Dust Mask |
| X | X |
16 | Gas Mask |
| X | X |
17 | Disposable Overalls (as necessary) |
| X | X |
18 | Ropes, Cones and Barriers |
| X | X |
19 | Safety/Warning Signs |
| X | X |
20 | Changing/Washing Facilities |
| X | X |
21 | Methane Detector (as necessary) |
| X | X |
22 | Carbon Dioxide Detector (as necessary) |
| X | X |
23 | Oxygen Deficiency Detector (as necessary) |
| X | X |
24 | Other Gas Detectors (as necessary) |
| X | X |
25 | Face Shield |
|
| X |
26 | Disposable Waterproofs |
|
| X |
27 | Wellington Boots with Sole and Toe Protection |
|
| X |
28 | Respiratory Equipment (as necessary) |
|
| X |
29 | Decontamination Unit |
|
| X |
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BTEX Considerations
The primary byproduct of manufacturing processes is associated polycyclic aromatic hydrocarbons, or PAHs, and certain volatile organic compounds (VOCs).
At the surface, these chemicals evaporate readily and dissipate, but may remain underground for a long time. Benzene, toluene, ethyl benzene, and xylenes (BTEX) are the primary VOCs, which may remain at old industrial sites.
BTEX describes this group of chemicals that are sweet smelling liquids which rapidly volatize in the air, can partially dissolve to surface or ground water, or can be bound to soils and sediments.
Human Health Effects: Occupational exposure to BTEX can result in adverse health effects e.g. skin and respiratory irritation, central nervous system depression, and maybe cancer. Whenever possible, exposure to BTEX chemicals should be minimized.
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Planning for Site Visit
Planning for Field Trip
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Key messages
Contamination of land or water, vegetation and air, needs to be determined accurately before restoration or remediation efforts are initiated.
The CSA framework is a structured and accepted approach to understanding and documenting levels of contamination and vital to determining any remediation actions.
The first step or phase of the CSA framework is the Preliminary Site Assessment, which usually does not involve sampling.
Preliminary Site Assessment, together with background data gathering, should provide enough information to develop the first Conceptual Site Model, which is vital for understanding the characteristics of the contamination.
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