Alberta Tier 2 Petroleum Hydrocarbon Guideline Calculation Software

Transcription

1 PTAC Soil and Groundwater Forum and Poster Session Alberta Tier 2 Petroleum Hydrocarbon Guideline Calculation Software Presented by Anthony L. Knafla M.Sc., DABT Sunita Ranganathan M.Sc. March 22, 2011

2 Software Tool Agenda Background Software Architecture Basis Uses Tier 2 Assumptions / Parameters Live Demo 2

3 Acknowledgements Petroleum Technology Alliance Canada (PTAC) AUPRF (Alberta Upstream Petroleum Research Fund) Distributed with direction from, Canadian Association of Petroleum Producers (CAPP) Small Explorers and Producers Association of Canada (SEPAC) Mike Morden Suncor Energy Project champion Miles Tindal (MEMS) Peer reviewer review to be completed April/May

4 Background AENV Tier 2 framework for guideline calculation for PHCs (petroleum hydrocarbons) and other substances Tool developed based entirely on AENV Tier 2 Framework, Equations, and Parameters, except Algorithm added to allow for the calculation of subsoil gas (vapour) guidelines in anticipation of upcoming Canadian guidance NOT an AENV endorsed program PTAC tool Will be available for download from the PTAC website Validity recalculation of Tier 1 guidelines for all PHCs, all receptors and exposure pathways Peer Review by an expert involved with the development of Tier 2 guidelines 4

5 Software Architecture Code Visual Basic Front end Microsoft Excel back end Can be installed on end user computers as a stand alone Visual Basic User Manual PDF file & context help button for basic instructions Optional Training Course Consistency Accuracy No exam not an AENV endorsed tool 5

6 Uses for the Calculator Application for the Upstream, Midstream, and Downstream Oil and Gas Sectors Data gap analysis Explore modification of input parameters Mandatory triggers for a Tier 2 assessment Sizeable or deep impact suggesting exploration of a Tier 2 guideline with greater parameter refinement may be of value for remediation volume estimation Support of risk management strategies Explore risk limiting pathways and receptors Tier 2 Soil, Groundwater, and Soil Gas Guidelines 6

7 Mandatory Triggers for a Tier 2 (and/or SSRA) Assessment CONDITION Land/water use not captured by generic Tier 1 land uses Exposure pathway is present that is not considered at Tier 1 for the land use Human receptors spend more time at the site on average, or receive higher levels of exposure than assumed at Tier 1 for the land use (e.g. higher produce consumption from site) Ecological receptors with high sensitivity Atypical building construction (earthen floors, crawlspace, low air exchange, etc.) Surface water body within 10 m of contamination Contaminated groundwater in contact with stagnant surface water body Coarse sand/gravel soils with Darcy velocity greater than the default velocity (3 x 10-7 ). This may occur for sites with high hydraulic conductivity (> 320 m/y) or where groundwater gradients are greater than those used in the default Tier 1 guidelines (0.028 m/m). Contaminated soil source within 30 cm of existing building foundation or contaminated groundwater or capillary fringe that has potential to be within 30 cm of the building (based on potential for seasonal groundwater fluctuation). Contamination in fractured bedrock RESPONSE REQUIRED Site-specific risk assessment Add exposure pathway (Tier 1 or Tier 2) or proceed to site-specific risk assessment Tier 2 Guideline Adjustment or site-specific risk assessment or apply more conservative land use at Tier 1 Site-specific risk assessment to ensure sensitive species are protected level Generally Tier 2 Guideline Adjustment but may require more detailed site-specific risk assessment Tier 2 Guideline Adjustment or site-specific risk assessment Site-specific risk assessment Tier 2 Guideline Adjustment or site-specific risk assessment Conduct Tier 2 Guideline Adjustment for the vapour inhalation pathway using a default attenuation coefficient of 0.01 (dilution factor of 100) or proceed to site-specific risk assessment. Site-specific risk assessment Reference: Alberta Tier 2 Soil and Groundwater Remediation Guidelines (December 2010). 7

8 Tier 2 Guideline Modification and Pathway Exclusion Covered by the Tool Pathway Comments Human Direct Soil Contact Cannot be modified or excluded. Vapour Inhalation Can be modified but not excluded. Protection of Potable Water Can be modified or excluded. For exclusion at Tier 2, DUA must be shown to be isolated from any contamination by a natural geological barrier. Ecological Direct Soil Contact Cannot be modified or excluded. Can be adjusted for Tier 2 site specific risk assessment of certain chemicals. Soil/Food Ingestion Cannot be modified or excluded. (livestock and wildlife) Protection of Aquatic Life Can be modified and excluded at Tier 2. Livestock Watering Can be modified and excluded at Tier 2. Wildlife Watering Can be modified and excluded at Tier 2. Irrigation Watering Can be modified and excluded at Tier 2. Other considerations Offsite migration Management Limits Cannot be modified but may be excluded if there is no potential for more sensitive land uses in the vicinity of the site. Cannot be modified or excluded.

9 Modification or Exclusions of Pathways at Tier 2 Groundwater Pathway Comments Human Vapour Inhalation Can be modified but not excluded. Protection of Potable Water Can be modified or excluded. For exclusion at Tier 2, DUA must be shown to be isolated from any contamination by a natural geological barrier. Ecological Direct Soil Contact Cannot be modified or excluded. Can be adjusted for Tier 2 site specific risk assessment of certain chemicals. Protection of Aquatic Life Can be modified and excluded at Tier 2. Livestock Watering Can be modified and excluded at Tier 2. Wildlife Watering Can be modified and excluded at Tier 2. Irrigation Watering Can be modified and excluded at Tier 2. 9

10 Primary Tier 2 Adjustable Parameters Soil Properties Dry bulk density, particle size density Moisture content (seasonal extensive data) Total porosity (calculated) Air-filled porosity (calculated) Water-filled porosity (calculated) Change as a package Source Dimensions Source length / width Depth to bottom of contamination Thickness of contamination Change as a package Hydrogeological Parameters Saturated hydraulic conductivity and hydraulic gradient Depth to groundwater Independent Parameters Soil organic carbon fraction Soil vapour permeability (can be a more difficult challenge) Distance to receptor Distance from contamination to foundation slab 10

11 Secondary Tier 2 Adjustable Parameters Building Properties only if more sensitive than Tier 1 Building length Building width Effective building height Depth to foundation base Change as a package Foundation slab thickness Crack area / length Pressure differential Air exchange rate Other Mixing zone thickness Thickness of the unconfined aquifer (DUA) Note: Adjustment of building properties is not normally permissible at Tier 2, except to evaluate a building more sensitive than the Tier 1 default. 11

12 Soil Vapour Guidelines - Allows for guideline development and comparison against measured data still must meet soil/groundwater guidelines for other pathways - tool provides preliminary background for data collection 12

13 Soil Vapour Wells - Install in vadose zone - Multiple vapour wells (nested) improves understanding of vapour flow - Concentrations may decrease at shallower depths due to anaerobic degradation, correlated with depleted O 2 and evolved CO 2 Can sample soil gas with SUMA canisters SUMA CANISTER VAPOUR SCREEN AND DRIVE POINT 13