Emma Kirsh, B.Sc., P.Geol & Douglas Sweeney, M.Sc, P.Eng. SEACOR Environmental Inc.

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2 Characterization & Assessment of LNAPL Mobility in Fractured Soils Emma Kirsh, B.Sc., P.Geol & Douglas Sweeney, M.Sc, P.Eng. SEACOR Environmental Inc.

3 Site Description Outline Previous Assessment Methodology Site Characterization Going Forward LNAPL Mobility Conceptual Migration Model Nature & Extent of Impact

4 Site Description Current tanks Typical retail fuel service station and pump in island southeast British Columbia ~ operating since at least 1961 Site Redeveloped cardlock in 2002 Current and former sets of pump islands, UST nests, former waste oil UST Diesel and regular gasoline still operational Former tanks and pump island

5 Site Description Southeast adjacent site vacant and owned by client ~ 120 m to southeast is Adjacent tributary North creek to major river in region Bounded by other vacant, Site Adjacent residential, streets, South commercial and railway in remaining directions Creek

6 Environmental Assessments Stage 1 and 2 Preliminary Site Investigations in 2000 and additional since Total of 76 monitor wells on site and off site surrounding properties On site & NW off site soil - BTEX, VPH > standards SE off site soil B, VPH > standards Groundwater BTEX, VH W, VPH, EPH w, LEPH w > standards

7 Investigation Methodology Objectives Detailed site characterization of soil and groundwater Develop LNAPL mobility assessment based on site characterization analysis Eventually develop remedial options based on site characterization analysis and LNAPL mobility assessment

8 Investigation Methodology Excavate two 5.0 m depth testpits downgradient from site parallel and perpendicular to groundwater flow direction Collect Shelby tubes every 1 m interval and jarred soil every 0.5 m In-situ fracture mapping Bedding, fractures, laminations, rootcasts Vertical and horizontal counts per linear meter

9 Investigation Methodology Test Pit Location Collect soil for typical hydrocarbon parameter Depth % analyses Fines - % Sand - Atterberg Limits (m) % Gravel Shelby tubes collected for Dry bulk density (6) Grain size analysis/hydrometer (9) Atterberg limits (1) Moisture content (6) Tempe cell analysis - Soil Water Characteristic Curve (SWCC) (1) Dry Bulk Density (ρb) (kg/m3) TP Water Content (%) Porosity (-) TP TP TP101 - East side TP101 - East side CL - Low plasticity clay TP101 - West side TP101 - West side TP102 - South side TP102 - South side Geometric Means Additional Constants: Value: Units:

10 Site Characterization Stratigraphy thin horizontal bedded clayey silt with occasional sand laminations between silt beds Soil oxidized to maximum testpit depth Variable clay content maximum % at m, then decreasing with depth Atterberg limits CL low plastic clay and even though clay content does not approach 50% even small clay content strong governing factor for key soil properties

11 Site Characterization Fracture mapping highest 2-4 m depth horizontal - ranged from 1/m to 17/m with 10/m average vertical ranged from 6/m to 31/m with 18/m average Bedding thicknesses (70-100mm or 14/m to 10/m) generally consistent at observed depth

12 Site Characterization Hydrogeological parameters from ongoing monitoring events Horizontal flow in 2 main directions Southeast from site towards creek and northwest towards road-some site mounding component and utilities/infrastructure control on movement Vertical flow variable downward depending on season/proximity to creek, m/m, average 0.01 m/m

13 Site Characterization Monitor Well TABLE 5: SUMMARY OF HYDRAULIC CONDUCTIVITY TESTING Hydraulic Soil Type Conductivity Screen Interval (mbgs) (m/s) September 2005 event conducted month prior to test pits Depth 2.5 m to 5.0 m NW gradient ~ m/m SE gradient ~ m/m K tests on 12 wells screened at various depths Geometric mean in upper 6 m 8 x 10-7 m/s Geometric mean below 6 m 1 x 10-7 m/s Intrinsic Permeability (m 2 ) BH26S Silt 1.1E E-14 BH26DR Silt 2.6E E-15 BH27S Sand 6.7E E-13 BH27D Sand 2.5E E-14 BH32S Silt 1.4E E-13 BH32D Silt 3.6E E-16 BH50S Silt 3.2E E-14 BH50D Silt 2.0E E-14 BH52S Silt 1.2E E-12 BH52M Sand 1.1E E-13 BH52D Sand 5.2E E-14 BH53D Silt 4.9E E-14 Geometric mean for wells in upper 6 m of soil 8.3E E-13 Geometric mean for wells in soil below 6 m depth 1.4E E-14

14 Fracture Flow System Horizontal Fracture Flow Cubic Fracture Flow Site Characterization MATRIX POROSITY geotechnical testing mean for matrix 47% Average Fracture Mean Hydraulic Fracture Spacing Conductivity FRACTURE Spacing APERTURE/POROSITY Snow (1968) flow through analogous to laminar flow between smooth parallel plates measured K value is equivalent horizontal K of orthogonal network of fracture system equation modification for flow system dominated by horizontal bedding or cubic fractures mean K and field fracture spacing Horizontal system % Cubic system % TABLE 6: SUMMARY OF FRACTURE APERTURES & POROSITIES Aperature Width (1/m) (m/s) (m) min 9 8.E E-05 max 17 8.E E-05 average 14 8.E E-05 min 9 8.E E-05 max 31 8.E E-05 average 15 8.E E-05 Fracture Porosity (%)

15 Nature & Extent of Hydrocarbon Impacts Plot 3: Groundwater & Product Elevations - BH 9 Elevation (m asl) Plot 3: Groundwater & Product Elevations - BH 9 BH 9 GW Elevation BH 9 LNAPL Elevation LNAPL ~ 10 monitor wells (1-500 mm) Plot 5: Groundwater & Product Elevations - BH Jan-01 Apr-02 Jun-02 Aug-02 Oct-02 Oct-02 Feb-03 Date (mmm-yy) Apr-04 Mar-05 Jun-05 Sep-05 7 wells - single LNAPL occurrence (max Plot 6: Groundwater & Product Elevations - BH mm) wells 3-10 occurrences, larger thicknesses Elevation (m asl) Elevation (m asl) Elevation (m asl) Jan Presence in conjunction with groundwater lows Date (mmm-yy) Apr-02 Apr-02 Jun-02 Jun-02 Aug-02 Oct-02 Aug-02 Oct-02 Oct-02 Feb-03 Date (mmm-yy) Oct-02 Feb-03 Apr-04 Apr-04 Mar-05 Mar-05 Jun-05 Jun-05 Sep-05 Sep-05 Elevation (m asl) Elevation (m asl) BH 9 GW Elevation BH 9 LNAPL Elevation BH 20 GW Elevation BH 20 LNAPL Elevation BH 23 GW Elevation Apr-02 BH 23 LNAPL Elevation Jun-02 Apr-02 Jun-02 Aug-02 Aug-02 Plot 5: Groundwater & Product Elevations - BH 20 Oct-02 Oct-02 Feb-03 Date (mmm-yy) Apr-04 Mar-05 Jun-05 Plot 6: Groundwater & Product Elevations - BH 23 Oct-02 Oct-02 Date (mmm-yy) Apr-04 Mar-05 Jun-05 Sep-05 Sep-05 BH 20 GW Elevation BH 20 LNAPL Elevation BH 23 GW Elevation BH 23 LNAPL Elevation Apr-02 Jun-02 Aug-02 Oct-02 Oct-02 Apr-04 Mar-05 Jun-05 Sep-05 Date (mmm-yy)

16 Nature & Extent of Hydrocarbon Impacts Residual phase 186 soil hydrocarbon analyses TOTAL PETROLEUM HYDROCARBONS 89 % soil TPH < 100 mg/kg (165) 21 % soil TPH ~ mg/kg (21) Oil saturations Maximum 0.8 %, majority <0.2 % Fracture flow porosity Volumetric oil content ( %)

17 Nature & Extent of Hydrocarbon Impacts TABLE 10: SUMMARY OF GROUNDWATER CHEMISTRY RESULTS WITH DISSOLVED TPH > 40,000 ug/l Sam ple ID Date VHw LEPHw HEPHw TPH BH 2D 25-Aug BH Dissolved 2D phase 24-Oct groundwater 5000 < BH 3 24-Oct <1000 hydrocarbon analyses BH 7 26-Jan < BH 8 26-Jan < BH 9 26-Jan < BH Jan TOTAL PETROLEUM HYDROCARBONS >70,000 BH Jan < BH Jan < BH 23 3-Mar μg/l < BH Indicator 23 of 3-Mar-05 LNAPL typical solubility < BH 50D 6-Aug BH ranges 50M 23-Jul < BH 50M 6-Aug < BH 96 52M % groundwater 23-Jul-02 TPH < 40, μg/l <1000 (496) BH 52M 6-Aug BH 4 52S % groundwater 23-Jul-02 TPH ~ < BH 52S 6-Aug < ,000-7,000,000 μg/l (19) BH Apr <

18 Nature & Extent of Hydrocarbon Impacts Extent of dissolved phase 150 m Presence of LNAPL or dissolved phase concentrations indicative of LNAPL over 150 m down gradient Extent of LNAPL 120 m

19 Conceptual Migration Model EVIDENCE FRACTURE Migration FLOW Hydraulic IS Model Gradient Conductivity Effe ctive DOMINANT MECHANISM LNAPL Average Linear Travel Migration Groundwater Time Model Velocity Porosity (m/s) - (m/m) (m/yr) (years) (m) Matrix Flow 8E Observed bedding & fracture network Travel time analysis supports cubic system Correlation of TPH in soil with fracture porosity Continuous system high downgradient dissolved concentrations (150 m) & minimal mixing occurring Cubic Fracture Flow Horizontal Fracture Flow Cubic Fracture Flow Horizontal Fracture Flow TABLE 11: SUMMARY OF GROUNDWATER TRAVEL TIME CALCULATIONS Travel Distance 8E E E E

20 Soil-Water Characteristic Curve for Clayey Silt Matrix Multi Phase Model LNAPL Distribution and Mobility based 60 on Multi phase model Advanced 50 in the early 1990 s by Farr and Parker 40 Core physical property of the multi phase 30 approach Air is Entry the value N = Moisture 1.6 Retention Curve 120 kpa Grain 20 size or Alpha Tempe =.06 1/mcell to obtain moisture retention curve parameters 10 API Models based on van Genuchten/Brooks 0 Corey parameters θ (%) Matric suction (kpa)

21 Multi Phase Oil Oil Saturations Saturations Model (%) (%) AMERICAN PETROLEUM INSTITUTE (API) LNAPL MOBILITY TOOL 4.5 Depth Below Surface (m) Van Genuchten (1980) parameters define moisture retention curve of soil 5.55 Gasoline standards 5.5 DENSITY OIL/WATER INTERFACIAL TENSION OIL/AIR 6 INTERFACIAL TENSION VISCOSITY 7 Input of N parameters LNAPL and = 0.5 m α from curve fitting spreadsheet 8 Input additional site data 7 LNAPL = 2.1 m

22 LNAPL Mobility Assessment Fluid Retention in Fractured Soil Dr. Mendoza (1992) derived constitutive relationships for fluid flow and migration in fractured geologic media Based on physical principles Invasion percolation theory Inlet accessibility & fluid trapping criteria Developed a numerical model with a log normal fracture aperture distribution and a log aperture variance of 1 Results apply for any fractured soil retention curve with known geometric mean aperture Critical assumption of aperture log normal distribution

23 θ (% ) LNAPL Mobility Assessment Soil-Water Theoretical Curve for Fractured Soil Moisture Retention in Fractured Soil Fracture system at site scaled to known Mendoza curve Based on ratio of geometric mean aperture width Mendoza mean = 25 μm Site mean = 32 μm Scaling Mendoza 3 kpa curve and Van Genuchten parameters to develop moisture retention curve Air Entry value N = 6 Alpha = 1.8 1/m Matric suction (kpa)

24 LNAPL Mobility Assessment Depth Below Surface (m) Compared 4.5 TPH data to API Model for fractured soil 5 parameters Oil Saturations (%) LNAPL = 0.5 m LNAPL = 1.2 m

25 LNAPL Mobility Assessment LNAPL behavior/observations Dissolved plume stability Theoretical Mobility Assessment using API Tools

26 LNAPL Mobility Assessment 7 monitor well locations single observation no new wells with LNAPL down gradient Mann-Kendall statistical trend test 36 wells on and off site with minimum 4 sampling events for analysis Shallow, mid-level and deep wells Stability results: 13 diminishing plume trend (on & off) 22 stable plume trend (on & off) 1 expanding plume trend (off) Supporting LNAPL plume stability Mann-Kendall Analysis of Plume Monitor Well No. BH 32S Event 2 Event 3 Event 4 Event 1 Event 5 Event 6 Event 7 Event 8 Event 9 Sum Rows Total BTEX (ug/l) Row 1:Compare to Event Row 2:Compare to Event Row 3:Compare to Event Row 4:Compare to Event Row 5:Compare to Event Row 6:Compare to Event Row 7:Compare to Event Row 8:Compare to Event Mann-Kendall Statistic (S) = TOTAL 11 Confidence Level Chart Stability Evaluation Results S Total No. Sampling Events Value S No Trend Indicated Plume is stable 0 ± 1 ± 2 No Trend Indicated S Trend is Present ( 90% Confidenc ± 3 S < 0 - Diminishing Plume ± 4 S > 0 - Expanding Plume ± 5 ± 6 ± 7 ± 8 ± 9 ± 10 ± 11 S ± 12 ± 13 ± 14 Trend Probably Present ± 15 ( 90% Confidence) ± 16 ± 17 ± 18 ± 19 >20

27 LNAPL Mobility Assessment Macro Scale Mobility API modeling with developed moisture retention curve, fracture porosity and gasoline properties V LNAPL 5 x 10-4 m/day V ASTM de minimus 9 x 10-4 m/day Micro Scale Mobility Local displacement head based on air entry value ( 0.3 m) and LNAPL properties (Brooks - Corey) H calculated 0.65 m H site maximum observed 0.5 m Macro/micro scale suggest LNAPL no longer mobile

28 Going Forward Now established network allowing key monitoring points for trend observation plume center of mass evaluation Future implications of low water table and LNAPL drainage - extended drawdown/pump tests Coring and UV light fluorescence for field LNAPL saturation verification Risk Assessment and Remediation

29 QUESTIONS?