Integrated Site Assessments and Risk Assessment for a Proposed Real Estate Transaction at a PCE-impacted Drycleaner Site

Transcription

1 Integrated Site Assessments and Risk Assessment for a Proposed Real Estate Transaction at a PCE-impacted Drycleaner Site B.J. Min, M.Eng., P.Eng. a, Geordie Clyde, P.Biol. b a Environmental Engineer/Risk Assessor Jacques Whitford Limited, Calgary, Alberta b Environmental Risk Assessor Jacques Whitford Limited, Calgary, Alberta ABSTRACT An integrated site assessment and risk assessment approach was used during the due diligence of a proposed real estate transaction at a perchlroethylene (PCE, also known as tetrachloroethylene)-impacted drycleaner site. PCE impacts were identified underneath the footprint of the dry cleaner. A quantitative risk assessment (QRA) was implemented as part of an integrated and life-cycle management approach to assess the impacts on the site. Advantages of a risk assessment are; i) flexibility - risk-based approach allows examination of management options that best fit with client or site priorities, ii) wellaccepted process - it has been recognized and approved by regulators and accepted by appropriate stakeholders (including clients and lenders); and iii) providing a costeffective remedial and/or risk management option for only those sites or areas where there is an actual risk to either humans or the environment. The objectives and scope of QRA program were strategically developed based on a concept of this integrated and life-cycle management approach. The QRA program included three major components; i) further soil and groundwater delineation; ii) indoor air quality assessment and iii) a risk assessment. The risk assessment component included the following: problem formulation, receptor characterization, exposure assessment, dose-response assessment, risk characterization, uncertainty assessment and recommendations for remediation/risk management. The end result was Win-Win as the real estate transaction was completed and the purchaser was successful in obtaining the necessary insurance and financing to complete the transaction. INTRODUCTION An integrated site assessment and risk assessment approach was used during the due diligence of a proposed real estate transaction at a PCE-impacted drycleaner site. PCE is a manufactured chemical used primarily for dry cleaning and metal degreasing. PCE and its breakdown products (i.e. trichloroethylene (TCE), 1,1 dichloroethylene, cis-1,2- dichloroethylene, trans-1,2-dichloroethylene and vinyl chloride) are commonly detected at sites where dry cleaning activities have occurred.

2 The subject site is located in Airdrie, Alberta and occupied by two single story retail malls and other retail buildings. The dry cleaning facility is located in one of the single story retail malls. The area around the site consists of predominantly commercial land use with some residential use. The surrounding areas are: north commercial land use; east commercial land use; west: residential land use across from Nose Creek; and south: commercial and residential land use. The Site is relatively flat and the topography in the area of the Site generally slopes from east to west. Regional groundwater flow is in a westerly direction towards Nose Creek, located approximately 80 m west of the dry cleaners. Comment [CS1]: Is this too specific so the location is identified? Does it matter? Just wondering if we are not suppose to ID the site/client Environmental assessments were previously conducted in 1996 and 2003 at the subject property and the 2003 environmental assessment report suggested improvement of chemical storage and work practices at the on-site dry cleaning facilities. In December 2004, a Phase I Environmental Site Assessment (ESA) was conducted by Jacques Whitford for a purchaser of the property. The Phase I ESA identified potential environmental concerns from volatile organic compounds (VOCs) associated with an onsite dry cleaning operation. Following the 2004 Phase I ESA, in December 2004, Jacques Whitford conducted the Phase II ESA, including the drilling of five boreholes with two monitoring well completion. The results of the Phase II ESA identified the following: The soil beneath the site consists of surficial asphalt/concrete, sand/gravel fill to 4.4 meters below grade (mbg), underlain by fractured sandstone bedrock. Groundwater elevations across the site ranged from m to m (local survey datum). No phase-separated liquids were detected in any of the monitoring wells. Calculated groundwater surface elevations indicate that the groundwater flow direction is towards the southwest; PCE concentrations in soil samples collected and analyzed from borehole BH1/MW1 exceeded the CCME (2004) SQG commercial land use guidelines at depths of mbg and mbg. PCE concentrations were 1.26 mg/kg and 2.48 mg/kg. (CCME Criterion: 0.5 mg/kg for commercial land uses) Concentrations of all other VOCs analyzed in the soil samples satisfied the applicable regulatory guidelines; PCE concentrations in groundwater samples collected and analyzed from monitoring wells MW1 and MW2 exceeded the CCME (2004) freshwater aquatic life water guideline (111 µg/l ) for PCE. Tetrachloroethene concentrations detected in the groundwater collected from well MW1 were 339 µg/l and 153 µg/l in well MW2. Concentrations of all other VOCs analyzed in the groundwater samples satisfied the applicable regulatory guidelines; and Based on the review of data, soil contamination primarily exists in boreholes MW1 and MW2 ranging from near surface depths to approximately 4 mbg in the source area. Overall, soil impact in the vicinity of the dry cleaning operation has been estimated at approximately 1,000 m 3-1,500 m 3.

3 INTEGRATED RISK-BASED APPROACH A QRA was implemented as part of an integrated and life-cycle management approach to assess the impacts on the Site. Advantages of a risk assessment are; i) flexibility - riskbased approach allows examination of management options that best fit with client or site priorities, ii) well-accepted process - it has been recognized and approved by regulators and accepted by appropriate stakeholders (including clients and lenders); and iii) providing a cost-effective remedial and/or risk management option for only those sites or areas where there is an actual risk to either humans or the environment. The objectives and scope of QRA program were strategically developed based on a concept of this integrated and life-cycle management approach. The QRA program included three major components: i) further soil and groundwater delineation; ii) indoor air quality assessment and iii) a risk assessment. The risk assessment component included the following: problem formulation, receptor characterization, exposure assessment, dose-response assessment, risk characterization, uncertainty assessment and recommendations for remediation/risk management. SUPPLEMENTARY INVESTIGATION AND INDOOR AIR QUALITY ASSESSMENT The following tasks were conducted for the supplementary investigation: line locates; drilling five boreholes to a maximum depth of 4.4 m below grade (mbg) to evaluate soil conditions, subsurface staining, and hydrocarbon vapour levels; installation of five groundwater monitoring wells (one in each borehole) for monitoring groundwater elevation, accumulated well headspace vapours, and the presence of liquid hydrocarbon; chemical analysis of soil and groundwater samples to quantify the level of volatile organic carbon parameters; surveying the groundwater monitoring wells to establish surface grade and groundwater elevations; site monitoring including measurement of groundwater levels and subsurface vapour concentrations within groundwater monitoring wells; and summarizing the findings of the field investigation and a discussion of the results in the context of the applicable CCME guidelines. Based on the current and foreseeable land use at the site, the CCME commercial soil quality guidelines (SQG) were recommended for evaluation of environmental impacts to soils (i.e., from dry cleaning compounds). The CCME drinking water (DW) and FAL guidelines were used to evaluate the environmental impacts to groundwater since the site was not in close proximity to surface water receptors. However, it should be noted that the site and area surrounding the site are supplied by the City of Airdrie municipal water system. Therefore, local groundwater is not used as a potable water source. CCME DW guidelines were therefore used strictly for environmental liability purposes. Due to the close proximity (approximately 20 m) of Nose Creek, the FAL guidelines were likely Comment [CS2]: This is a run-on sentence please break down into sentences.

4 applicable unless these were shown that the shallow groundwater underlying the site did not discharge into Nose Creek. The indoor air quality assessment included the following scope: conducting an interior inspection in the areas of air sampling to identify potential sources of VOCs that may affect or interfere with the indoor air sampling and recording real-time measurements using a PID; air sampling using SKC Universal XR sample pumps using thermal desorption tubes; laboratory analysis of the samples to quantify the level of volatile organic carbon parameters; and summarizing the findings of the field investigation and a discussion of the results in the context of the applicable occupational health and safety guidelines the 8 hr threshold limit value (TLV) and risk-based reference values indicating concentrations of the parameters showing no human health adverse effects. For interpretation of the analytical results of the indoor air samples, the 8 hr TLV was considered to be one of the appropriate values for comparison the laboratory analytical results and risk-based reference values indicating concentrations of the parameters showing no human health adverse effects were used as reference criteria. Figure 1 shows soil, groundwater and indoor air sampling locations. Findings from the supplementary investigation indicated that the spatial distribution of PCE soil impact is localized primarily beneath the footprint of the dry cleaning space and east towards the monitoring well location MW2 (approximately 5 m east of the dry cleaner). The worst case concentrations appear to exist in the shallow soil layer underlying the dry cleaning machine. The results of the soil delineation indicate that there is no evidence of off-site migration associated with the PCE impact in the soil, and no migration is expected in the future and dissolved-phase PCE groundwater impact, above the applicable regulatory guideline, is presently localized to beneath the building in the area of the dry cleaning operation and east towards the MW2. The results of the groundwater delineation indicate that there are no off-site migration impacts of PCE in the groundwater, and no such impacts are likely. For the indoor air quality assessment associated with PCE impacts, a total of seven air quality samples were collected in the dry cleaner, surrounding tenant locations and background locations. Detectable PCE concentrations in the indoor samples collected from the dry cleaner premises and adjoining tenant locations were recorded; however, the results were below their respective 8 hr TLV and the risk based reference values.

5 FIGURE 1. Sampling Locations and Groundwater Flow Direction

6 TIER II MODIFICATION AND QUANTITATIVE RISK ASSESSMENT METHODOLOGIES Alberta Environment (AENV) allows modification of generic regulatory guidelines by replacing generic parameters used in the calculation of guidelines for individual pathways with site-specific information. The modification of generic guidelines is referred to as a Tier II approach. The methodology and applicable information are outlined in the following documents: Canadian Council of Ministers of the Environment (CCME), Protocol for the Derivation of Environmental and Human Health Soil Quality Guidelines; CCME, Canada Wide Standards for Petroleum Hydrocarbons (PHCs) in Soil: Scientific Rationale- Supporting Technical Document; and AENV, 2001b. User Guide Alberta Soil and Water Quality Guidelines for Hydrocarbons at Upstream Oil and Gas Facilities Volume 3. These documents recommend using similar methods and assumptions as those used to develop the Canadian Soil Quality Guidelines (CCME, 2004), which are the generic regulatory criteria considered appropriate for evaluating impacted soil at the site. Modified generic criteria must be protective of both current and reasonably foreseeable future land uses. PROBLEM FORMULATION Identification of CoPC Chemicals having concentrations in subsurface soil or groundwater at the site greater than the generic guidelines for a commercial land use setting were considered CoPCs for the purpose of the QRA. PCE is currently the only chemical found to exceed the applicable guidelines in soil and/or groundwater. Table 1 below, summarizes the potential soil and groundwater CoPCs identified at the site. Table 1 Chemicals of Potential Concern Chemicals of Potential Current Maximum Measured Concentration Carried Forward in Concern Source Indoor Air (mg/m 3 ) Soil (mg/kg) Groundwater (mg/l) Risk Assessment Chloroform < 0.03 < No PCE Operations Yes TCE associated < < Yes 1,1-DCE with the NS < 0.03 < Yes cis-1,2-dce on-site dry < 0.03 < Yes < Trans-1,2-DCE cleaner. < 0.03 < Yes Vinyl Chloride < < 0.03 < Yes

7 Notes: Maximum parameter concentrations in soil, groundwater, and/or indoor air based on Phase II and supplementary ESA (Jacques Whitford) analytical results. NS = not sampled 1 = total isomers Chloroform is listed as a CoPC as it was detected in indoor air; however, it was not detected in the soil and groundwater on site, and therefore it does not appear to be related to the identified on-site impacts. Receptor Identification Human Receptors The current and potential future site building is modelled as a slab-on-grade structure for commercial use. The potential human receptors, or people who may be most affected by the CoPCs for the current and intended land use were identified as toddlers for noncarcinogens and adults for carcinogens with no extreme sensitivities. No off-site receptors were included because CoPCs have not and are not expected to go off-site. Ecological Receptors The site is located within an urban area primarily developed for commercial land uses. The site contains buildings, asphalt, and very few landscaped areas. As such, there is no ecological habitat at the site and no rare or endangered terrestrial receptors are anticipated to be present. The nearest natural ecological habitat to the site is the Nose Creek (approximately 80 m west). The direction of shallow groundwater flow at the site has been identified as westerly. The lack of VOCs detected in the two monitoring wells located in between the dry cleaner s and Nose Creek in the direction of groundwater flow indicates that the VOC impacted groundwater has not migrated to the creek and likely will not. As no ecological receptors are anticipated to be impacted by the CoPCs, ecological receptors have not been assessed further as part of the Tier 2 modification process or the QRA. Exposure Pathway Evaluation The exposure pathway evaluation examines the likelihood that receptors at the site may come into contact with CoPCs. It was assumed that property usage at and near the site would not materially change in the future. The exposure scenarios that were considered for the human receptors are presented below.

8 Exposure Pathway Description (On-site and Off-site) Ingestion of surface soil Dermal contact with surface soil Inhalation of dust Ingestion of surface water Dermal contact with surface water Ingestion of groundwater Dermal contact with groundwater Ingestion of vegetation Ingestion of garden produce Table 2 Potential Exposure Scenarios Likelihood of Exposure Very Unlikely Very Unlikely Very Unlikely Very Unlikely Carried Forward for Quantitative Analysis? No No No No Justification The site is covered and the CoPCs were identified at a depth of 2.0m below ground surface. Therefore, dermal contact, ingestion of soil, and the inhalation of dust by any receptor is very unlikely. There are no surface water bodies on-site and transport to surface water is not expected, based on analytical results. The closest surface water in the direction of groundwater flow is Nose Creek, located approximately 80 m west of the dry cleaner. Groundwater at the site and within the City limits is not used as a potable drinking water source. Soil and groundwater impacts have not been identified in the surface soil, and are therefore below the root uptake zone of most plants. The identified impacts are on a commercial site, where there is no grown produce. Inhalation of subsurface soil vapours indoors Inhalation of groundwater vapours indoors Inhalation of subsurface soil vapours outdoors Inhalation of groundwater vapours outdoors Possible on-site Nothing off-site. Unlikely Yes No Soil and groundwater vapours may migrate into the on-site commercial buildings becoming available for receptors through inhalation exposure. VOC vapours may migrate into outdoor air on-site becoming diluted in outdoor air and the inhalation by a receptor is unlikely to represent appreciable exposures when compared to the greater potential from indoor air exposures.

9 Conceptual Exposure Model The conceptual model developed for evaluating the quantitative exposure of the receptors under current industrial development scenarios (based on current concentrations) includes: VOC vapours from the impacted soil and groundwater diffuse upward through the soil and into the dry cleaner building through cracks in the floor slab. On-site receptors may inhale the vapours in indoor air. The exposure assessment has been performed considering the current and foreseeable use of the site as a commercial property, and that groundwater use in the area will not change in the future (i.e., will not be used for potable supplies). Receptor Characterization The use of the site was estimated to be daily, for on-site receptors. Receptors were assumed to be on-site for 10 hours/day, 5 days/week, 48 weeks/year for up to 56 years (Health Canada, 2003). This exposure time is considered to be conservative compared to the typical exposure that a worker would receive on any given day (i.e. 8 hr shift). TIER 2 MODIFICATION OF THE GENERIC RISK BASED REMEDIATION GUIDELINES The Tier 2 modification of generic risk based remediation guidelines considered those contaminants detected in soil or groundwater at concentrations greater than the applicable generic guideline on the site (i.e., PCE) and was conducted in accordance with the appropriate regulatory documents (CCME 1996, 2001, AENV 2001). AENV has endorsed the use of the vapour intrusion model developed by Johnson and Ettinger (1991) for predicting vapour concentrations migrating into a building. This model was utilized by the CCME (2001) to develop the Tier 1 guidelines for petroleum hydrocarbons and by AENV (2001) to derive soil and groundwater hydrocarbon guidelines for upstream oil and gas locations. US EPA s Version 3.0 of the Johnson and Ettinger (1991) model (J&E) was used for estimating subsurface vapour intrusion into buildings from soil and groundwater, to modify vapour inhalation pathway guidelines. The final PCE risk based quality guidelines (RBQG) for soil and groundwater are presented in Table 3.

10 Table 3 Modified Risk-Based Soil and Groundwater Quality Guidelines for Inhalation of Vapours in Indoor Air Parameter Soil (mg/kg) Maximum Measured Concentration RBQG Groundwater (mg/l) Maximum Measured RBQG Concentration PCE The maximum measured concentrations of PCE in both soil and groundwater were below the RBQG. The maximum indoor air concentration of PCE (0.56 mg/m 3 - detected in Bay 113) was greater than the Health Canada (1996) tolerable concentration of 0.36 mg/m 3, which is generally the airborne concentration to which it is believed a receptor (including children) can be exposed continuously over a lifetime without deleterious effects (based on non-carcinogenic effects). This indicates that if another business occupies that bay, risk to future receptors associated with exposure to PCE vapours at existing concentrations within the dry cleaner area should be reevaluated at that time. QUANTITATIVE RISK ASSESSMENT (QRA) The QRA was conducted to derive risk based remediation criteria (RBRC) for the degradation products of PCE, (e.g., TCE, DCE, cis-1,2-dce, trans-1,2-dce, and vinyl chloride) even though concentrations at the subject site were below guidelines and method detection limits. Exposure Assessment The QRA for this site was conducted with the aid of the US EPA s Version 3.0 of the Johnson and Ettinger (1991) model. For the purposes of the assessment, it was assumed that the maximum CoPC soil and groundwater concentrations measured to date were present beneath the entire floor slab. With the exception of TCE in groundwater, concentrations equivalent to half of the method detection limit (MDL) were used to derive RBRC for the other PCE degradation products, as no measurable concentrations have been detected on the site. For TCE in groundwater, the maximum measured concentration to date was used. Dose Rate Estimates The predicted indoor air concentrations were calculated for non-carcinogenic and carcinogenic chemicals separately. The predicted indoor air concentrations were higher than the measured indoor air concentrations (which were all below the method detection

11 limits), indicating the conservatism of the modelling. The predicted indoor air concentrations were used to calculate hazard quotients and incremental lifetime cancer risks. Dose-Response Assessment For the purpose of this assessment, toxicity reference values were obtained for each of the CoPCs. Toxicological information was obtained from various sources, including Health Canada and the Integrated Risk Information System (IRIS) database from the US EPA. For non-carcinogenic contaminants, the toxicity reference values were provided as a reference concentration (RfC) for inhalation exposure. For cis-1,2-dce and trans-1,2- DCE toxicity data for inhalation exposures was not available; therefore, inhalation RfCs were extrapolated from published oral reference doses (RfD) using a toddler body weight of 16.5 kg (Health Canada, 2003) and a toddler inhalation rate of 9.3 m 3 /day (Health Canada, 2003) to be conservative. For carcinogenic contaminants, a risk specific concentration (RsC), corresponding to a 1 in 100,000 target risk level, was provided for inhalation exposures. Toxicity reference values for each CoPC are presented below: Table 4 Toxicity Reference Values Chemical RfC (inhalation) (mg/m 3 ) RSC (inhalation) (mg/m 3 ) TCE NA 1.64E-02 c cis-1,2-dce 1.77E-02 b NA trans-1,2-dce 3.55E-02 a NA 1,1-DCE 2.00E-01 a NA Vinyl Chloride NA 2.30E-03 a Notes: A US EPA IRIS database, 2004 b US EPA PPRTV, 2002 c Health Canada, 2003 Risk Characterization An estimate of the potential risks from exposure to CoPC in subsurface soil or groundwater is calculated by comparing the exposure estimate to the toxicity reference dose. For a non-carcinogenic chemical the risk characterization is expressed as a Hazard Quotient (HQ), such that: 3 estimated indoor air concentration (mg/m ) HQ = 3 reference concentration (mg/m )

12 Generally, for non-carcinogens a risk estimate of greater than 1 from all sources of exposure represents a potential health concern that should be more closely examined. However, it is common practice (Health Canada, 2003) to assume that a receptor would receive 80% or 0.80 of exposure from sources that are not associated with the site. Therefore, a risk estimate greater than 20% or 0.2 from all the routes of exposure at the site was considered to represent a potential health concern that should be more closely examined. For non-threshold acting chemicals the incremental lifetime cancer risk (ILCR) for the site is calculated as: 3 Indoor Air Concentration (mg/m ) ILCR = Target Risk x 3 Risk Specific Concentration (mg/m ) An ILCR of greater than one in one hundred thousand (1 x 10-5 ) is indicative of a potential health concern that should be more closely examined. Table 5 Summary of Risk Estimates Parameter HQ ILCR Sub-Surface Soil TCE NA 7.30E-08 cis-1,2-dce 9.96E-03 NA trans-1,2-dce 8.39E-03 NA 1,1-DCE 3.31E-03 NA Vinyl Chloride NA 5.22E-06 Groundwater TCE NA 1.26E-08 cis-1,2-dce 1.62E-04 NA trans-1,2-dce 1.92E-04 NA 1,1-DCE 9.91E-05 NA Vinyl Chloride NA 9.69E-08 Total TCE NA 8.57E-08 cis-1,2-dce 1.01E-02 NA trans-1,2-dce 8.58E-03 NA 1,1-DCE 3.41E-03 NA Vinyl Chloride NA 5.31E-06 Notes: NA not applicable

13 ILCR estimates and HQ estimates were found to be acceptable for all CoPCs for on-site workers and toddlers spending large amounts of time at the site. RBRC were back-calculated using a target HQ of 0.2 and an ILCR of 1E-05 and are presented in Table 6 below. Concentrations below the RBRC are not expected to pose an unacceptable risk to on-site receptors; using the assumptions made for the purpose of this assessment. Table 6 Risk Based Soil and Groundwater Remediation Criteria 1 Parameter Non-Carcinogen Carcinogen Maximum Maximum Measured RBRC Measured RBRC Concentration Concentration Sub-Surface Soil (mg/kg) TCE NA ND 2.06 cis-1,2-dce ND 1.10 NA trans-1,2-dce ND 1.30 NA 1,1-DCE ND 3.30 NA Vinyl Chloride NA ND Groundwater (mg/l) TCE NA cis-1,2-dce ND 4.51 NA trans-1,2-dce ND 3.79 NA 1,1-DCE ND 7.35 NA Vinyl Chloride NA ND 0.10 Notes: 1 based on HI of 0.2 and ILCR of 1E-05 targets in coarse-grained soil. NA not applicable ND not detected BOLD indicates maximum measured concentration exceeds minimum calculated risk-based guideline The maximum measured concentrations of the identified CoPCs are less than the calculated RBRCs. UNCERTAINTIES In order to have confidence in the conclusions of a risk assessment, there must be: i) a high level of certainty; ii) an acceptable and reasonable level of conservatism (i.e., an over-statement of risk); or iii) an appreciation of the bounds on the final solution. The exposure assessment conducted as part of the risk assessment for the subject site was based on: i) measured values and site observations where available; and ii) conservative assumptions for certain parameters, where required.

14 Uncertainties associated with the estimation of the toxicological effect of a chemical are inherent in the risk assessment process. For instance, when assessing the toxicity of a chemical, it is not ethical to experiment on human receptors. As a result, toxicologists must rely on animal data, toxicological models, and epidemiological studies to estimate the effect of a chemical. In addition, the availability of toxicological data is often limited because of the vast number of chemicals potentially present in the environment and the high costs associated with conducting these studies. To compensate for such shortcomings and the related uncertainties, a number of uncertainty factors are typically built into the dose-response process, which predicts the toxicity of a chemical. Although this results in a conservative estimate of risk, the confidence in the accuracy of that risk is suspect. It should be noted that the risk assessment was developed for current site conditions. With further PCE degradation, the concentrations of vinyl chloride and the other intermediate degradation products can potentially increase. This should be taken into account when developing the future monitoring plan for the site, i.e., it may be prudent to plan for monitoring of site conditions and have a contingency plan to address the possibility that conditions may worsen in the future. An off-site QRA was not conducted as no off-site impacts were identified. DISCUSSION AND CONCLUSIONS The Tier 2 modification of generic criteria and QRA was conducted for potential future on-site scenarios. Potential risks were quantified for the receptors that may be exposed to potential CoPC at specific areas of environmental concern. The exposure pathways evaluated in this assessment consisted of the inhalation of volatiles in indoor air. The use of site-specific data to generate modified risk-based soil and groundwater quality guidelines has resulted in an increase over the generic guidelines. The QRA did not predict unacceptable risks to receptors at the site under the current land use scenario for any of the CoPCs. In summary, using the conservative assumptions presented in this report, potential adverse health effects are unlikely to be associated with the exposure of receptors to the maximum concentrations of CoPC measured to date. The Tier 2 modified generic criteria and RBRC derived for the CoPCs are protective of human health. If higher concentrations of CoPC are identified during monitoring activities at the site at a later date, the conclusions of the risk assessment may have to be modified. Also, if site use changes from the assumptions made for the purpose of this assessment then it will be necessary to revisit this risk assessment.

15 Based on the findings, a risk management plan was developed and is being conducted to monitor the residual of PCE in soil, groundwater and potential indoor air intrusion. The end result was Win-Win as the real estate transaction was completed and the purchaser was successful in obtaining the necessary insurance and financing to complete the transaction. REFERENCES AENV, User Guide Alberta Soil and Water Quality Guidelines for Hydrocarbons at Upstream Oil and Gas Facilities Volume 3. CCME A Protocol for the Derivation of Environmental and Human Health Soil Quality Guidelines. Canadian Council of Ministers of the Environment. CCME Canadian Council of Ministers of the Environment (CCME) Canadian Environmental Quality Guidelines (1999) Revised CCME Canada-Wide Standards for Petroleum Hydrocarbons (PHCs) in Soil: Scientific Rationale, Supporting Technical Document, December Canadian Council of Ministers of the Environment. Johnson, P.C and R.E. Ettinger, Heuristic Model for Predicting the Intrusion Rate of Contaminant Vapours into Buildings. Environ. Sci. Technol. 25, Health Canada Health-Based Tolerable Daily Intakes/Concentrations and Tumorigenic Doses/Concentrations for Priority Substances. Ottawa: Minister of Supply and Services. Health Canada Federal Contaminated Site Risk Assessment in Canada. Part 1: Guidance on Human Health Screening Level Risk Assessment (SLRA). Version 1.1. October 3, U.S. EPA PPRTV Derivation Support Document for cis-1,2-dichloroethylene (CASRN ). SRC TR / U.S. EPA Integrated Risk Information System. IRIS Database On-Line Search. U.S. Environmental Protection Agency, Cincinnati, OH.

16 SHORT BIOGRAPHY B.J. Min, M.Eng., P.Eng. is an environmental engineer / risk assessor in Jacques Whitford s Environmental Risk Assessment Service line in Calgary. He has had 10 years of environmental engineering and consulting experience in a wide range of projects including environmental risk assessment and management, site assessment and remediation, and hazardous waste management for the upstream and downstream oil and gas industry, residential, commercial, industrial and petrochemical industry. He obtained his Bachelor of Science in Environmental Engineering from the Ajou University in South Korea and his Master of Engineering from the University of Calgary in Calgary, Alberta. As a project manager at Jacques Whitford, Mr. Min pursues implementation of environmental risk assessment & management as an integral and lifecycle risk management tool for contaminated site remediation and management. Geordie Clyde, P.Biol. is an environmental risk assessor with 10 years experience in conducting qualitative and quantitative human health and ecological risk assessments. Mr. Clyde obtained his Bachelor of Science degree in Ecology from the University of Calgary, and is a professional biologist with a background in aquatic ecology and environmental technology. He has conducted numerous assessments of contaminated sites that have been impacted by hydrocarbons, chlorinated solvents, polycyclic aromatic hydrocarbons (PAH s) and metals. Prior to working with Jacques Whitford, Mr. Clyde worked with other consulting firms as a risk analyst. His responsibilities include: writing and reviewing human health and ecological risk assessment, presenting risk assessment results to clients and other parties, critical review of client presented documents, data compilation and interpretation as well as stochastic and deterministic risk assessment modelling.