Module 4 - Phase III Site Assessments - Presentation - Updated Fall 2024 PDF

Le Portage Golf Club, Cheticamp October 16, 2021 1  ENVI 3138 MODULE 4 Phase III Site Assessments 2 RECAP!! Phase I Review of existing information typically consisting of: Records review – multiple sources Aerial photogr...

Le Portage Golf Club, Cheticamp October 16, 2021 1  ENVI 3138 MODULE 4 Phase III Site Assessments 2 RECAP!! Phase I Review of existing information typically consisting of: Records review – multiple sources Aerial photography Site visit Interviews Reporting Phase 1 outcome?? DESKTOP EXERCISE!! Is it likely or not that I have a problem at my site? 3 RECAP!! Phase II Field Work Involves characterization of a site for the physical aspects and the potentially contaminated site media by most likely contaminants. Phase II involves sampling of site media Determines pathways and receptors A good assessment can outline what is where and at what levels Phase II outcome?? Location, concentration, phase and types What contaminants do I likely have a problem with at my site? 4 Phase III Environmental Site Assessments Fine Tuning Phase Detailed Assessment to characterize the site All contaminants known and there spatial relationships are outlined Pathways and receptors are fully outlined Inputs for remediation and risk assessment Phase III outcome?? All inputs available for determination of remedial plan Go out to know more if required 5 Brownfields vs Greenfields The US Environmental Protection Agency definition of a Brownfield: A brownfield is a property, the expansion, redevelopment, or reuse of which may be complicated by the presence or potential presence of a hazardous substance, pollutant, or contaminant. It is estimated that there are more than 450,000 brownfields in the U.S. Cleaning up and reinvesting in these properties increases local tax bases, facilitates job growth, utilizes existing infrastructure, takes development pressures off of undeveloped, open land, and both improves and protects the environment. A brownfield as land or buildings, typically in urban areas, the further use of which may be hampered Fact Sheets: by the presence of pollution or contaminants. Greenfields are areas available for development on the edges of urban areas or in suburban locations. 6  Fact Sheets Hyperlinked 7  Fact Sheets Hyperlinked 8 9 10 11 Phase III ESA Objectives Description of the sites hydrogeology Hydrogeology is the area of geology that deals with the distribution and movement of groundwater in the soil and rocks of the Earth's crust. Identification of the source(s) of contamination A characterization (details!) of the size and type of contaminants 12 Phase III ESA Objectives cont’d Definition and delineation of the horizontal and vertical extent of the contamination and identification of the boundary of the contaminant FINE TUNING!! plume Detailed stage Contamination migration pattern rate of movement Pathways & receptors After Phase II have general idea After Phase III have details-volume , flow rates, dose, etc. 13 Phase III ESA Objectives cont’d An estimated volume of contaminated soil & determine extent to which GW has been impacted (include volume as well) Evaluate the potential for health & ecological impacts by: Identifying receptors Determining pathways for contaminant movement Assess exposure risk by conducting risk assessment (Qualitative & Quantitative) Pathways and Receptors?? Sydney Tar Ponds 14  Pathways Food Receptors Food Hazard Air Soil etc. Water NOTE: No Pathway = No Exposure = No Risk 15 Risk Assessment Quantitative Qualitative Lots of #s Conservative vs Uses scoring – can vary score Subjective Must be very certain National Classification System for Contaminated Can determine cost impact Sites (CCME) Qualitative Risk Analysis Quantitative Risk Analysis The process of prioritizing risks for subsequent The process of numerically analyzing the effect on overall project objectives of identified risks. further analysis or action by assessing and combining their probability of occurrence and impact. 4 As per PMBoK 16 Example of Qualitative Risk Assessment 17 National Classification System Tool to aid in the evaluation of contaminated sites. Provides scientific and technical assistance in the identification and prioritization of sites, which may be considered to represent high, medium, or low risk. Classifies contaminated sites into these general categories of risk in a systematic and rational manner, according to their current or potential adverse impact on human health and/or the environment. Class 1: High Priority for Action Class 2: Medium Priority for Action Class 3: Low Priority for Action Class N: Not a Priority for Action Class INS: Insufficient Information Hyperlink 30 - 69 18 Phase III ESA Objectives cont’d Compare contaminant concentrations with established federal & provincial assessment and remediation guidelines If guideline is exceeded and there is potential exposure risk, decide whether to proceed with remediation or develop site specific guidelines (Remedial Objectives) using Risk Assessment techniques Determine whether remediation is required 19 20 21 22 23  Environmental Risk Risk ❑The possibility that an undesirable outcome may result from an uncertain situation. ❑The likelihood of injury, disease, or death. ❑Individuals may be voluntarily or involuntarily exposed to chemicals at home, at school, in the workplace, while traveling etc. 24  Environmental Risk Defined: ❑The risk resulting from exposure to a potential environmental hazard. ❑Hazards may include: Biological pathogens Stratospheric ozone depletion Climate change Water scarcity Soil contamination Etc. 25  Environmental Risk Environmental Risk ❑ The concept of environmental risk can be applied to the health of plants, animals, and entire ecosystems 26 Hazardous includes any adverse impact to humans or to the environment as a result of exposure to a chemical or material. There are many hazards beyond toxicological. 27  Environmental Risk Relationships among risk, hazard, and exposure are extremely important. What happens if the Many current methods depend almost controls fail? Risk is exclusively on controlling exposure. Is this a problem? then equal to a function Health & Safety typically depends on controls or of hazard!! systems that can fail or be sabotaged (intentionally or accidentally). Alternative, what about relying on the use of benign chemicals and materials. Risk = f (hazard, exposure) 28  Environmental Risk Limitations of Controlling Exposure ❑ Failure of an engineered control system allowed for the exposure of humans and the environment to a hazardous release. ❑ Case Study: ❑ Bhopal, India ❑ December 1984 ❑ Water entering into the tank of Methyl Isocyanate from Union Carbide factory. This caused a reaction which lead to the release of toxic Methyl Isocyanate gas. The release of this toxic gas resulted in the death of thousands of people and caused irreversible harm to the environment. ❑ Bhopal Gas Tragedy ❑ BBC Documentary (53 mins duration) 7 53 Risk = f (hazard, exposure) Graphic Content 29  Environmental Risk Hazardous Waste and Toxic Chemicals Exposure ❑ Exposure can result in death, disease, or some other adverse impact such as a birth defect, infertility, or neurological Chronic disorder. Exposure over a long time or ❑ In humans, this contact is typically through ingestion, constantly recurring inhalation, or skin contact (dermal). ❑ Exposure can be associated with: Acute ✓ Drinking water Exposure over short period or ✓ Eating food experienced over a severe or ✓ Ingesting soil and dust intense degree ✓ Inhaling air borne contaminants (vapour or PMx) 30  Environmental Risk Toxicity ❑Dealing with the effects of chemicals on living organisms ❑Energy and material are distributed and cycled through food webs thus there is likely that an impact on one level will be reflected in other levels. ❑Toxic effects can be divided into two types: 1) Carcinogenic 2) Noncarcinogenic 31  Environmental Risk Carcinogens ❑Promotes or induces tumours (uncontrolled or Known Human Carcinogens ▪Benzene abnormal growth and division of cells) ▪Vinyl chloride ❑Attack or alter the structure and function of DNA ▪Arsenic within a cell ▪Hexavalent chromium ▪Others ❑Many are site-specific (a particular chemical tends to affect a specific organ). Probable Human Carcinogens ❑Categories: ▪Benzo(a)pyrene ▪ Primary carcinogens directly initiate cancer ▪Carbon tetrachloride ▪ Pro-carcinogens are not carcinogens but are metabolized to form ▪Cadmium carcinogens and thus indirectly initiate cancer ▪PCBs ▪ Co-carcinogens are not carcinogens but enhance the carcinogenicity ▪Others of other chemicals ▪ Promoters enhance the growth of cancer cells 32  Environmental Risk Noncarcinogens ❑Effects include all of the toxicological responses other than carcinogenic ❑Countless examples: ❑ Organ damage ❑ Neurological damage ❑ Suppressed immunity ❑ Birth and developmental effects Continuum of health risks due to exposure to noncarcinogens ranging from less serious to more serious 33  Environmental Risk Exposure Pathways ❑ There are three basic exposure pathways for humans. They are: 1. Ingestion (eating and/or drinking) 2. Inhalation (breathing) 3. Dermal (skin) Contact ❑ Some chemicals can be lethal to test animals in very small doses, whereas others create problems only at much higher levels. 34  Environmental Risk Expressing Toxicity ❑Median Lethal Dose (LD50) The dose that results in the death of 50 percent of a test organism population. Typically presented as the mass of contaminant dosed per mass (body weight) of the test organism. Units: mg/kg Median Lethal Concentration (LC50) Used in studies of aquatic organisms and represents the ambient aqueous contaminant concentration (as opposed to injected or ingested dose) at which 50 percent of the test organisms die. 35 The regulatory documents…. REVIEW REMAINING SLIDES AND READING (DOCUMENT) PRIOR TO ASSIGNMENT NO. 4 36 Environmental Quality Standards For Contaminated Sites Nova Scotia Environment (NSE) administers the Contaminated Site Regulations pursuant the Environment Act. Provides detailed reference information and rationale that was used to develop tables for the: NSE Tier I Environmental Quality Standards (Tier 1 EQS) NSE Tier II Pathway Specific Standards (Tier 2 PSS) These are the regulatory numerical standards used in Nova Scotia for notification, assessment and remediation of contaminated sites. 37 Environmental Quality Standards For Contaminated Sites In 2009, NSE formed a Numerical Standards and Site Assessment Methodologies Working Group (NSSAM Working Group) Scientific Experts Advisory Research Reporting in 2011 which forms the rationale and background for this document. 38 Environmental Quality Standards For Contaminated Sites The objectives of this document are: to provide the basis and rationale for the development and subsequent adoption of environmental quality standards for the application to contaminated sites in Nova Scotia to provide site professionals and others with an understanding of the hierarchy of jurisdictional sources used and the source references for environmental quality standards used in the Nova Scotia Tier 1 EQS and Tier 2 PSS tables to provide site professionals with guidance in applying the environmental quality standards in conjunction with the Contaminated Sites Regulations. 39 Environmental Quality Standards For Contaminated Sites Development of numerical environmental quality standards for the notification, assessment, and remediation of contaminated sites in NS is based on the following factors: ❑ Relevant Media ❑ Potential Contaminants of Concern ❑ Land use classification, usage and activities incorporating assumptions concerning receptors ❑ Soil Texture ❑ Exposure ^^Let’s look at these^^ 40 Environmental Quality Standards For Contaminated Sites Relevant Media ❑ Soil ❑ Groundwater ❑ Surface Water (Fresh & Marine) ❑ Sediment 41 Environmental Quality Standards For Contaminated Sites Potential Contaminants of Concern ❑ Master list of potential CoCs for all media of interest has been developed. ❑ Based on experiences at contaminated sites in NS and considers environmental quality benchmarks from other Canadian and US jurisdictions. ❑ Note: Each site and/or situation may warrant a specific evaluation and assessment to determine which, if any, of the potential CoCs may be present. Note: For some exposure pathways in the Tier 1 or Tier 2 tables, there may be no chemical guideline or standard available. In such cases, the absence of an applicable standard is also indicated in the tables. 42 A CAS Registry Number, also referred to as CAS RN or informally CAS Number, is a unique numerical identifier assigned by the Chemical Abstracts Service (CAS) to every chemical substance described in the open scientific literature. Currently it includes all substances described from 1957 through the present, plus some substances from as far back as the early 1800s. 43 44 45 46 Environmental Quality Standards For Contaminated Sites Land Use Classifications ❑ The exposure frequency, duration and intensity for human and ecological receptors at a contaminated site are related to the nature of the land use, the activities inherent to that land use and the ease of access to site media (CCME, 2006). ❑ The four CCME land use categories are as follows: 1) Agricultural In applying the Tier 1 EQS and Tier 2 PSS, the land use 2) Residential/Parkland category that is most consistent with, or applicable 3) Commercial to, the current site land use and activities (and/or future land use where applicable) must be 4) Industrial considered. 47 Sensitivity to Contamination by Land Use/Activity (CCME, 2006) Where do the land use categories fall in terms of sensitivity to contamination?? 48 Sensitivity to Contamination by Land Use/Activity (CCME, 2006) 49 Environmental Quality Standards For Contaminated Sites 1) Agricultural Growing crops Tending Livestock Dairy Includes lands that provide habitat for resident and transitory wildlife and native flora Agricultural lands are generally accessible by the owner and family members who represent the more sensitive human receptor category. Only land use categories that include direct ecological soil pathways in addition to human health exposure pathways in the derivation of criteria at the Tier 1 EQS level. Undeveloped, wild or natural land uses that are not otherwise zoned as residential/parkland, commercial or industrial use should follow agricultural land use criteria. 50 Environmental Quality Standards For Contaminated Sites 2) Residential/Parkland Residential or recreational activity. This category assumes parkland can be a buffer between areas of human residency and includes campgrounds. Does not include undeveloped wild lands—such as, national or provincial parks. Long-term-care institutional facilities may be considered as residential land uses depending on site specific circumstances. 51 Environmental Quality Standards For Contaminated Sites 3) Commercial Commercial land use properties span a wide variety of activities with varying degrees of access to human and ecological receptors. Shopping malls Offices Schools Hospitals Religious facilities Operations where food is grown would be excluded from this category. 52 Environmental Quality Standards For Contaminated Sites 4) Industrial Production, manufacture or construction of goods Industrial properties span a wide variety of land uses and activities but generally do not permit direct public access, (except workers). Access to industrial properties is often limited for ecological receptors. 53 Environmental Quality Standards For Contaminated Sites Soil Texture Classifications ❑ A physical parameter used in the NSE EQS determination tables and should be considered when conducting site assessments. Two categories. ❑ Fine-grained Soil ❑ Material having greater than 50% (by dry weight) particles equal to or less than 75 microns (200 mesh) in diameter. ❑ Fine-grained soil numerical standards must be supported with data from a sieve analysis from the appropriate soil zone. ❑ Coarse-grained Soil ❑ Material having greater than 50% (by dry weight) particles equal to or greater than 75 microns (200 mesh) in diameter ❑ Generally, coarse-grained soil numerical EQS are lower. 6 54  Environmental Quality Standards For Contaminated Sites Exposure Pathways ❑CCME provides guidelines for exposure pathways which cover most of the range of potential exposures found at contaminated sites. Human Exposure Pathways Ecological Exposure Pathways 55 Environmental Quality Standards For Contaminated Sites Exposure Pathways ❑ Human Exposure Pathways Media Exposure Pathways ▪ Direct Contact (Ingestion and/or Dermal Exposure) ▪ Vapour Migration (Inhalation of Indoor Air) ▪ Dust Inhalation (Inhalation of Outdoor/Indoor Air) Soil ▪ Soil Leaching for Protection of Potable Groundwater (Water Ingestion) ▪ Off-site Migration ▪ May be evaluated in similar manner as soil under certain Sediment conditions Surface Water ▪ Ingestion as Drinking Water or Incidental Water Ingestion ▪ Ingestion as Drinking Water Groundwater ▪ Vapour Migration (Inhalation of Indoor Air) 56 Environmental Quality Standards For Contaminated Sites Exposure Pathways ❑ Ecological Exposure Pathways Media Exposure Pathways Soil ▪ Soil Contact (Plants and Soil Invertebrates) (Agricultural Land ▪ Soil and Food Ingestion (Livestock or Wildlife) Uses Only) ▪ Nutrient and Energy Cycling ▪ Direct Contact with Sediments (Freshwater and Marine Sediment ▪ Benthic Aquatic Life)a ▪ Direct Contact with Surface Water (Freshwater and Surface Water ▪ Marine Pelagic Aquatic Life)b ▪ Migration of Groundwater Contaminants to Surface Water Groundwater (Aquatic life)c Notes: a) Includes direct contact of gills and other respiratory surfaces with sediments; ingestion of sediment (including sediment pore water ingestion); ingestion of aquatic prey species and other food items—i.e., detritus, plants, phytoplankton, zooplankton, macroinvertebrate fauna, and fish; and root contact with sediment for aquatic plants. b) Includes direct contact of gills and other respiratory surfaces with water; ingestion of water; ingestion of aquatic prey species and other food items—i.e., detritus, plants, phytoplankton, zooplankton, macroinvertebrate fauna, and fish; and foliar contact with water for aquatic plants. c) Includes migration to a freshwater or marine surface water body such that aquatic organisms may become exposed to what was originally a groundwater contaminant. 57 Environmental Quality Standards For Contaminated Sites General Hierarchy of Environmental Quality Standard Sources The general hierarchy used to select environmental quality standards for use in Nova Scotia is outlined below: 1) Canadian Council of Ministers of the Environment (CCME): Canadian Environmental Quality Guidelines (CCME, 1999, and various updates up to and including 2010). 2) Health Canada (Guidelines for Canadian Drinking Water Quality, 2012). 3) Atlantic RBCA Version 3 Guidance (Atlantic PIRI, 2012). 4) Sources from other Canadian Jurisdictions (i.e. Alberta, Ontario, British Columbia, in order of preference). 5) United States Environmental Protection Agency (USEPA). 6) Other U.S. and International Jurisdictions (as deemed necessary). 58 Environmental Quality Standards For Contaminated Sites Standards for Protection of Human Health ❑ CCME generic guidelines often consider both ecological and human health effects. Where both values are available, the CCME selects the lower value as the final recommended guideline. ADJUSTMENT OF TARGET RISK LEVEL FOR EXPOSURE TO CARCINOGENS For the purposes of development of the EQS, Nova Scotia has incorporated a target carcinogenic risk level of 1E-05 (1 in 100,000). This is consistent with Atlantic PIRI and Health Canada (HC, 2004) science policy for sites under the four Atlantic Canada Provinces’ jurisdictions. In cases where original guidelines from other jurisdictions are based on a target cancer risk level of 1E-06 (1 in 1,000,000), these values have been adjusted to reflect a target risk level of 1E-05. 59 Environmental Quality Standards For Contaminated Sites Standards for Protection of Human Health ❑Human Health Based Standards for Soil Human receptors can be exposed to soil through a number of pathways including: ✓ Ingestion ✓ Dermal contact ✓ Vapour migration to indoor air and dust inhalation in outdoor air. The hierarchy used for the selection of human health-based EQS for soil generally considers the same four land uses and the same soil descriptions (coarse and fine grained). Hierarchy to use is the Canadian Soil Quality Guidelines for the Protection of Human Health (CCME, 2007b with various updates up to and including 2010) for all substances in the master list excluding BTEX and petroleum hydrocarbons; Canadian Soil Quality Guidelines for the Protection of Human Health for Polycyclic Aromatic Hydrocarbons (CCME, 2010) Human Exposures to Sediment ✓ At this time, there are no human health-based guidelines for sediment exposure although it is recognized that Health Canada is presently exploring the potential need for human health-based sediment quality guidelines. ? 60 Environmental Quality Standards For Contaminated Sites Standards for Protection of Human Health ❑Human Health Based Standards for Surface Water Typically focuses on protection of freshwater or marine aquatic life rather than human health. However, Health and Welfare Canada does provide Recreational Water Quality Guidelines (HWC, 1992) that may be used as guidance in assessing surface-water quality for such human activities as swimming, water sports and so on. In situations where surface water is used as a drinking water source or where there is believed to be a high potential for incidental ingestion of surface water, the Guidelines for Canadian Drinking Water Quality are recommended for use. The Nova Scotia EQS do not include specific human health-based standards for surface water quality. 61 Environmental Quality Standards For Contaminated Sites Standards for Protection of Human Health ❑Human Health Based Standards for Groundwater Human receptors can be exposed to contaminants in groundwater Need to determine primarily through direct ingestion and through vapour migration from availability of groundwater to indoor air. Municipal Water on site The hierarchy to use is Guidelines for Canadian Drinking Water Quality Are you in a Source Potable Groundwater Standards Water Protected Groundwater and surface water are integrally connected thus groundwater cannot be managed in isolation from surface water and aquatic ecosystems. Area? GW Protection Strong emphasis on preventing groundwater resources from becoming Strategy? contaminated. Where contamination occurs, it is vital to remediate or manage any impacts CBRM Groundwater adequately to ensure on-going protection of human health and the environment Protection Strategy and the restoration of beneficial uses. Groundwater potability must be confirmed in order to appropriately apply the relevant Tier 1 EQS. 62  Environmental Quality Standards For Contaminated Sites Standards for Protection of Ecological Health ❑ Ecological Health Based Standards for Soil All sources of ecological health-based EQS for soil provide guidelines for all land uses considered and for both coarse-grained and fine- grained soils where appropriate. Hierarchy is to use the Canadian Soil Quality Guidelines for the Protection of Environmental Health (CCME, 2007b with various updates up to and including 2010) for all substances in the master list except PAHs and petroleum hydrocarbons; Canadian Soil Quality Guidelines for the Protection of Environmental Health for Polycyclic Aromatic Hydrocarbons (CCME, 2010); CCME (2008) Canada Wide Standards for Petroleum Hydrocarbons. 63 Environmental Quality Standards For Contaminated Sites Standards for Protection of Ecological Health ❑ Ecological Health Based Standards for Sediment Various approaches to establishing a guideline. Co-occurrence data – correlations or co-incidence of benthic impacts with measured sediment chemical concentrations. Equilibrium Partitioning – defined as a special case of chemical equilibrium. This most commonly involves chemical equilibrium systems where reactants and products are in the same phase - either all gases or all solutions. However, it is also possible to get equilibria between substances in different phases, such as two liquids that do not mix (are immiscible). Hierarchy is to use the Canadian Sediment Quality Guidelines for the Protection of Aquatic Life (CCME, 2002) 64 Environmental Quality Standards For Contaminated Sites Standards for Protection of Ecological Health ❑ Ecological Health Based Standards for Surface Water The ecological health-based EQS for surface water are only for freshwater and marine aquatic life protection. The hierarchy considers the Canadian Water Quality Guidelines for the Protection of Aquatic Life (CCME, 2007a and various updates up to and including 2010) for all substances in master list except BTEX and petroleum hydrocarbons. 65  Environmental Quality Standards For Contaminated Sites Standards for Protection of Ecological Health ❑ Ecological Health Based Standards for Groundwater In Nova Scotia, ecological standards for groundwater are not provided at the Tier 1 EQS level in relation to notification of contamination, but are provided for information and use in the Tier 2 Pathway-specific Standards (PSS) tables. These groundwater ecological standards are solely based on providing criteria for groundwater that discharges to surface water. 66 Environmental Quality Standards For Contaminated Sites Consideration of Background Environmental Conditions ❑ Some substances that occur naturally in the environment and are not the result of human activity can exceed Tier 1 EQS. ❑ Historical practices or activities such as, fires, atmospheric emissions or even general urbanization may have resulted in concentrations of substances that exceed Tier 1 EQS over localized or widespread areas. ❑ The Notification of Contamination Protocol, PRO-100, provides information on the approach used to assess such background occurrences in Nova Scotia with respect to the Contaminated Sites Regulations. Sometimes, in the context of complex contaminated-site studies, more detailed information on background substances may be necessary. Additional data may also be required in instances where sites are determined to have combined impacts from background substances and contamination from a point source or sources. In such cases, a local background value for a substance for the purposes of remediation levels determination may be required. In Nova Scotia, there currently are no available databases of representative background environmental conditions at the local level. Thus, site-specific, local or regional environmental determinations of soil and water quality may need to be conducted by site professionals on a case-by-case basis if necessary. 67 Environmental Quality Standards For Contaminated Sites Nova Scotia Environmental Quality Standards ❑ Based on the assessment and consistent management of risks posed to human, ecological receptors and environmental processes under four common land uses— i.e., agricultural, residential/parkland, commercial, and Incorporate different amounts of site- industrial. specific information. An additional ❑ The basic EQS may be considered in two tiers: determination at the Tier 2 level may Tier 1 (generic) involve calculation of site-specific Tier 2 (pathway-specific) EQS which cleanup target levels (through the application of environmental risk assessment methods) otherwise known as Tier 2 SSTL’s. 68 Environmental Quality Standards For Contaminated Sites Nova Scotia Environmental Quality Standards ❑ The Tier 1 EQS and Tier 2 PSS are designed to achieve the same degree of human health and ecological protection Tier 1 EQS regardless of which option is used. ❑ The two options differ in the amount of site-specific information used to determine the criteria and the differences in site management which include land use or contaminant exposure management controls that may Tier 2 PSS result. 69 Environmental Quality Standards For Contaminated Sites Nova Scotia Environmental Quality Standards ❑ The Tier 1 Environmental Quality Standards The Tier 1 EQS are simple tabular values that require minimal site information for their use. Tier 1 EQS present the lowest of the pathway-specific Tier 1 EQS human health/ecological EQS where applied for each of the four land use categories and two soil texture categories. Those sites with conditions that are significantly different are more appropriately dealt with using a site-specific or Tier 2 PSS approach. 70 Environmental Quality Standards For Contaminated Sites Nova Scotia Environmental Quality Standards ❑ The Tier 2 Pathway Specific Standards If site concentrations exceed the Tier 1 EQS, they may be compared to the Tier 2 Pathway-specific Standards (PSS) with consideration of additional requirements imposed by the Contaminated Sites Regulations. The use of the Tier 2 PSS allows certain pathways to be either Tier 2 PSS excluded or otherwise managed provided there is proper site management and supporting documentation to do so. 71  Environmental Quality Standards For Contaminated Sites Nova Scotia Environmental Quality Standards ❑ Finally, refer to document for reference tables..... Hyperlinked 72  vs EXAMPLE Gas Station – has contamination and is above generic guidelines ❑If you have time - can go to Tier II ❑If you don’t have time - clean up to Tier I level ❑If you only have a few m3 of contaminated soil you are not going to spend a lot of money on a Risk Assessment – you’ll just dig it out!! 73 The End 74