A Hydrostratigraphic and Geochemical Data-driven Approach to the - - PowerPoint PPT Presentation
A Hydrostratigraphic and Geochemical Data-driven Approach to the Development of a CSM for the Analysis and Selection of Remedial Options at a FCSAP DNAPL Site Federal Contaminated Sites National Workshop 2016 Stantec Consulting Ltd. April
Federal Contaminated Sites National Workshop 2016 Stantec Consulting Ltd. April 2016
Methodology
The facility is currently used as a refinishing facility, which was constructed in stages between 2009 and 2012.
were observed in building excavations during construction.
approximately 3,242 tonnes of solvent impacted soil and 1,363,054 litres of solvent impacted groundwater were removed for off-site disposal.
within the vicinity of facility resulted in expanding the boundary of groundwater impacts to the north and south of the facility (Site).
comprised of unconsolidated fill and native glaciolacustrine or glacial deposits overlying the Paleozoic bedrock.
within the Study Area groundwater are Chlorinated Volatile Organic Compounds (CVOCs).
soil vapour.
A CSM capable of generating quantitative information for the analysis and selection of optimal remedial options was developed.
presentation of contaminated site characteristics (e.g., illustration or cartoon).
provide sufficient quantitative information (e.g., mass discharge estimates, remediation time frames) to perform a robust analysis critical to the selection of remedial options.
the analysis and selection of optimal remedial
A stepwise approach was used to develop the CSM for the Study Area, involving geospatial integration of geological, hydrogeological, geochemical, and site characterization datasets.
The quantitative information (e.g., estimates of contaminant mass and discharge rates by each hydrostratigraphic unit) derived during the CSM development process allowed for the identification of hydrostratigraphic units where enhanced passive or active remediation will be required.
Elevation (m AMSL) Major Soil or Bedrock Classification Group Geological Description USCS Symbols Conceptual Geological Units for the Site + 89 + 76 Topsoil, fill, asphalt Non-native Not Applicable (NA) Fill Coarse and Fine grained deposits Glaciolacustrine deposit SP, SP-SM, SM, ML Shallow Overburden Unit Coarse grained deposits Glacial Till or Diamicton (poorly sorted unconsolidated sediment) GP, GW, GM, SP, SP Till Fractured to sound bedrock Paleozoic bedrock of Verulam Formation NA Fractured Bedrock (RQD1 values <70) NA Sound Bedrock (RQD1 values ≥70)
Notes:
1 Rock Quality Designation (RQD) values expressed in percentage
Notes: 1 In the fractured media, the bulk retention capacity can be in the range of 0.0002 to 0.002 (UK EA, 2003). Fractured media cannot retain as much DNAPL per unit volume as unconsolidated deposits. In unconsolidated deposits (i.e., glacial till) can be in the range of 0.005 to 0.03 (UK EA, 2003). 2 Estimate based on information obtained from SSI#3 (December 2014). Potential Source Area Hydrostratigraphic Units /Lithology Surficial Extent of Source Area (m2) Average Thickness
Source Area (m) Soil /Bedrock Volume (m3) Bulk Retention Capacity1 TCE Volume (m3)2 Dry Density
/Bedrock Unit (kg/m3) Estimated TCE mass (kg) Source Area “A” Interface Aquifer – Glacial Till 320 2.76 883.2 0.005 4.42 1937 8561 Source Area “A” Interface Aquifer – Fractured Bedrock 320 0.79 252.8 0.0002 0.05 1427 71 Total Estimated TCE Mass in the Interpreted Potential Source Area “A”
8632
Source Area “B” Interface Aquifer – Glacial Till 1830 0.26 475.8 0.005 2.38 1937 4610 Source Area “B” Interface Aquifer – Fractured Bedrock 1830 3.49 6386.7 0.0002 1.28 1427 1826
Total Estimated TCE Mass in the Interpreted Potential Source Area “B” 6436
Hydrostratigraphic Units Chemical Estimates of Groundwater Volumes with Groundwater Concentrations ≥ Remediation Target Levels (m3) Shallow
Dichloroethene, cis-1,2- Dichloroethene, trans-1,2- Trichloroethene Vinyl chloride
Total for the Shallow Overburden Unit
Interface Aquifer Dichloroethene, cis-1,2- 34,100 Dichloroethene, trans-1,2- Trichloroethene 120,000 Vinyl chloride 67,500
Total for the Interface Aquifer 221,600
Sound Bedrock Dichloroethene, cis-1,2- Dichloroethene, trans-1,2- Trichloroethene 18,800 Vinyl chloride
Total for the Sound Bedrock 18,800
Elevation (m AMSL) Major Soil or Bedrock Classification Group Geological Description USCS Symbols Conceptual Geological Units Conceptual Hydrostratigraphic Units Hydrogeological Setting Geochemical Setting + 89 + 76 Topsoil, fill, asphalt Non-native Not Applicable (NA) Fill Unsaturated Zone Coarse and Fine grained deposits Glaciolacustrine deposit SP, SP-SM, SM, ML Shallow Overburden Unit Shallow Overburden Unit Faster Flow Regime with significant heterogeneities Largely aerobic with large sub-
anaerobic zones Coarse grained deposits Glacial Till or Diamicton (poorly sorted unconsolidated sediment) GP, GW, GM, SP, SP Till Interface Aquifer Faster Flow Regime with significant heterogeneities Largely anaerobic with pockets of aerobic and sub-oxic zones Fractured to sound bedrock Paleozoic bedrock of Verulam Formation NA Fractured Bedrock (RQD1 values <70) NA Sound Bedrock (RQD1 values ≥70) Sound Bedrock Aquifer Simple, slower flow regime Predominantly anaerobic
Notes: 1 Rock Quality Designation (RQD) values expressed in percentage
Notes: 1 Mass of BTEX (carbon donor) compared to mass of CVOC (TCE, cis-1, 2-DCE, Vinyl Chloride) estimated based
2 Estimated mass of BTEX in the source area based on December 2014 sampling results. 3 Available donor mass (kg-H2) = Carbon Donor to CVOC ratio x Mass of Carbon Donor required for the Dechlorination of TCE
Location Carbon Donor (Kg-H2 equivalent) to CVOC (Kg-H2 equivalent) Ratio1 Mass of TCE Daughter Products2 (kg –H2 equivalent) Available Donor Mass3 (kg –H2 equivalent) Sustainability of MNA Dissolved Phase Plume in groundwater (CVOC concentrations above the RTLS) 0.01 6.24 0.05 Unlikely, available donor mass < donor demand from competing electron acceptors (267 kg- H2/yr)
A A’
B B’
Sonny Sundaram, Ph.D, P.Geo. Jean Philippe Gobeil, M.Sc. Marc Bouchard, P.Eng. David Wilson, M.A.Sc., P.Eng. Stantec Ottawa