Date: March 23, 2018 Reference No.: VAN A0 To: cc: Mike Dolman Assistant Project Manager

Transcription

1 Wayburne Drive Burnaby, BC V5G 4W3 Canada T: Memorandum Date: March 23, 2018 Reference No.: VAN A0 To: Ministry of Transportation and Infrastructure Warren Lemsky, P.Eng. Project Manager Total No. of Pages: 9 + Attachments warren.lemsky@gov.bc.ca cc: Mike Dolman mike.dolman@gov.bc.ca Assistant Project Manager From: Matthew Munn, P.Eng. matthew.munn@exp.com Don Sargent, P.Eng. don.sargent@exp.com Project: Subject: Geotechnical Design Foundation Investigation Test Well Installation, Testing and Evaluation 1 INTRODUCTION In agreement with EXP Services Inc. s (EXP) work plan submitted to the Ministry on January 31, 2018, we have supervised the installation of a bedrock Test Well (designated TW18-1) near the west abutment of the proposed Walper Bridge Replacement Project (the Project) and completed standardized hydraulic testing and related monitoring designed to characterize the local groundwater system and evaluate the feasibility of depressurizing the bedrock during foundation construction. 2 METHODOLOGY 2.1 Test Well Installation (TW18-1) Test Well TW18-1 was constructed by a Certified Well Driller (Cariboo Water Wells Ltd.) on March 6 and 7, 2018, under supervision of EXP field staff and with remote direction from an EXP Senior Hydrogeologist. The well was constructed and designed in accordance with Water Sustainability Act and Groundwater Protection Regulation requirements, including provisions for flow control as defined under the Act. The drilling program and related hydraulic testing work was observed by a Triton Environmental Consultants Ltd. (Triton) Environmental Monitor, under separate contract with the Ministry. Test Well TW18-1 was constructed at a location approximately 9 m from the north end of the west abutment pile cap, as shown on Figure 1 (Attachment #1). A 12-inch diameter steel casing was initially driven to 5.2 m-bg (metres below ground) through a 1.8 m thick layer of surficial SAND & SILT into an underlying SILTY CLAY strata. An 8-inch diameter steel casing was then placed in the 12-inch casing and advanced to 7.7 m-bg into a water-bearing SILTY CLAY & GRAVEL encountered at 7.0 m-bg. The 12-inch casing was then cut-off at ground surface and a full profile concrete seal installed between the two casings. A 6-inch diameter steel casing (i.e., production casing) was then advanced through the 8-inch casing to 9.3 m-bg, approximately 0.9 m into water-bearing siltstone bedrock encountered at 8.2 m-bg. A steel plate with a 2-inch diameter valve fitting and pressure gauge was welded between the 8-inch casing and 6-inch production casing to provide control of groundwater flow from the 8-inch casing. A hose was attached to ISO 9001:2008 REGISTERED Page 1 of 9

2 Memorandum (cont d) Test Well Installation, Testing and Evaluation Project No.: VAN A0 March 23, 2018 the fitting to convey groundwater to a 1,500 gallon on-site storage tank. Open borehole drilling (6-inch diameter) in bedrock was then advanced to 18.3 m-bg and encountered fine-grained sandstone from approximately 15.2 m-bg to the full depth drilled. A full-length 4.5-inch diameter PVC liner with a 20-ft (foot) long machine-slotted screen section was inserted into the well, prior to attaching a pre-fabricated wellhead with a 2-inch valve fitting on the 6-inch diameter production casing. Test Well TW18-1 completion details are provided in a schematic illustration attached to this memorandum (Figure TW18-1, Attachment #2) and subsurface conditions encountered during drilling are described in TW18-1 Summary Log (Attachment #3). 2.2 Groundwater Quality Sampling An initial groundwater quality sample was collected by EXP staff on March 7 from the 8-inch casing, after allowing the casing to purge for approximately 2 hours. Triton staff delivered the sample on the same day to an accredited analytical laboratory depot in Fort St. John for testing and comparison with BC Water Quality Guidelines for Protection of Freshwater Aquatic Life (FWAL). A second water quality sample was collected on March 8, 2018 from the 6-inch production casing and delivered by EXP staff to the Fort St. John depot for FWAL analysis. At the time of preparing this memorandum, the resulting groundwater quality analytical reports have been delivered to Triton for their review of compliance with the FWAL Guideline. The groundwater either passively discharged from the well casings during drilling or intentionally purged from the casings was collected in the on-site storage tank and removed using a vacuum truck for off-site disposal. 2.3 Pressure and Flow Testing and Monitoring A temporary pressure transducer with automated data logger was installed in the 6-inch production casing at 08:00 on March 8, 2018, and programmed to record shut-in pressure (i.e., bedrock artesian pressure) at a 30-second frequency. A dial-type pressure gauge was also installed on the 8-inch casing to allow intermittent manual measurement of groundwater pressure within the 1.2 m thick SILTY CLAY & GRAVEL layer overlying bedrock. The automated transducer was removed from the production casing at 07:15 on March 9, 2018 after almost 24 hours of uninterrupted monitoring and the data downloaded and converted to equivalent above ground values (in metres). A continuous record of bedrock artesian pressures measured in the production casing and manual pressure readings from the 8-inch casing collected during the March 8-9, 2018 monitoring period are summarized on Figure 2 (Attachment #4). Hydraulic tests were completed in the Test Well casings by variably opening and closing the wellhead valves and monitoring the resultant groundwater pressure responses. Three primary tests were completed in the production casing and a supplementary test in the 8-inch casing. Measured end-of-test flow rates and corresponding water pressure changes (i.e., drawdown) for the three production casing tests are summarized on Figure 3 (Attachment #5). Test #1 During a 2-hour period commencing at 09:17 on March 8, 2018, the production casing valve was progressively opened in five (5) intervals of 20 to 25 minute duration and water flow rates from an in-line flow meter (1-inch diameter) recorded after each interval. Observed flow rates ranged from 0.16 USgpm (US gallons per minute) during the first interval to 7.18 USgpm during the final full-valve interval. After 121 minutes of continuous discharge, the production casing artesian pressure declined approximately 1.3 m (4.2 ft) from the pre-test level of 6.3 m above ground to 5.0 m above ground (Figure 2). The production casing valve was then closed to induce a rapid pressure recovery response. Page 2 of 9

3 Memorandum (cont d) Test Well Installation, Testing and Evaluation Project No.: VAN A0 March 23, 2018 Test #2 While the production casing pressure was in recovery mode following Test #1, the relatively small-diameter (1-inch) flow meter was removed from the flow wellhead assembly and replaced with a 2-inch discharge hose. Test #2 commenced at 11:48 on March 8, 2018 after allowing 30 minutes of pressure recovery in the production casing, by fully opening the 2-inch valve and allowing unrestricted flow for nineteen (19) minutes, before again abruptly closing the valve to induce a rapid pressure recovery response. An unrestricted end-of-test flow rate of 23.8 USgpm was measured and the corresponding water pressure drawdown was approximately 5.3 m (17.4 ft) below the pre-test level of 6.0 m above ground (Figure 2). Test #3 Following completion of Test #2, the production casing valve remained closed for 2.25 hours to allow pressure recovery. During this time a 2-inch diameter in-line flow meter was attached to the production casing wellhead and fully opened at 14:22 for 38 minutes. The end-of-test flow rate measured prior to closing the valve at 15:00 was USgpm and the corresponding pressure drawdown was again approximately 5.3 m (17.4 ft) below the pre-test level of 6.0 m above ground (Figure 2). Production casing pressure recovery was then monitored for approximately 16.5 hours. Supplementary Testing (8-Inch Casing) A supplementary test was completed during the production casing recovery period between Test #2 and Test #3, to additionally examine the relationship between the 8-inch casing pressure and production casing pressure. The 1-inch flow meter was attached to the 8-inch casing and the 8-inch casing valve progressively opened in five (5) intervals commencing at 12:38. After ninety-four (94) minutes of continuous discharge the full-valve flow rate was measured at 3.9 USgpm and the 8-inch valve closed at 14:12. Prior to the end of the flow interval, water pressure in the 8-inch casing had declined to a level equivalent to the pressure gauge position at 0.76 m above ground. 2.4 Hydraulic Conductivity Determination Data from the three production casing tests were analyzed to estimate the bulk hydraulic conductivity of the pressurized bedrock underlying the west abutment area. The observed pressure responses (Figure 2) were analyzed using AQTESOLV, which is a commercially available software designed specifically for the analysis of aquifer hydraulics. The Theis solution for a confined aquifer and a partially-penetrating well was selected and separate estimates for hydraulic conductivity determined for both the initial drawdown (i.e., flowing) phase and subsequent recovery (i.e., no flow) phase for the three tests. The resulting hydraulic conductivity estimates are summarized in Table 1. Table 1. Calculated Hydraulic Conductivity Hydraulic Conductivity (m/s) Test Number Drawdown Analysis Recovery Analysis x x x x x x 10-6 Geometric Mean 2.0 x x 10-6 Page 3 of 9

4 Memorandum (cont d) Test Well Installation, Testing and Evaluation Project No.: VAN A0 March 23, 2018 Hydraulic conductivity values estimated from drawdown data are relatively consistent and range from 1.6 x 10-5 m/s to 2.8 x 10-5 m/s, with a geometric mean value of 2.0 x 10-5 m/s. Values estimated from recovery data are likewise relatively consistent and range from 5.0 x 10-6 m/s to 6.7 x 10-6 m/s, with a geometric mean value of 6.1 x 10-5 m/s. Accordingly, the upper bound and lower bound values for hydraulic conductivity are estimated to be 2.0 x 10-5 m/s to 6.1 x 10-6 m/s, respectively, and are considered representative of a fractured rock mass. 2.5 Bedrock Depressurization Model Predictive tools in AQTESOLV were used to evaluate the feasibility of reducing bedrock artesian pressure to an equivalent water level of 1 m below the underside of the west abutment cap. This depressurization target is assumed to represent an overall artesian pressure reduction of 13 m at the west abutment, which includes the seasonal high artesian pressure of 11 m estimated for geotechnical borehole BH17-02 and the grade separation between BH17-02 and the abutment cap area. Four depressurization scenarios were modeled. Scenario #1 assumed Test Well TW18-1 was converted to a production well and operated independently. Scenario #2 assumed one new production well was constructed at a location offset from the south end of the west abutment and operated independently. Scenario #3 assumed Test Well TW18-1 was operated as a production well concurrently with a new production well offset from the south end of the west abutment. Scenario #4 assumed two new production wells were constructed at locations offset from the north and south ends of the west abutment and operated concurrently. Details for each scenario, including the resultant estimates of depressurization magnitude below the west abutment, are summarized in Table 2. Scenario #1 Production Well PW18-1 (TW18-1) The total depth of TW18-1 is 18.3 m-bg. Assuming a submersible pump is installed at the bottom of the well and a minimum 1 m submergence is maintained, the calculated maximum available drawdown in TW18-1 would be approximately 17 m and the maximum total head on the pump would be approximately 28 m based on an assumed seasonal high artesian pressure of 11 m. Using this total head and assuming the pump is operated continuously for 7 days, and utilizing the bounded hydraulic conductivity values summarized in Table 1, the highest pumping rate that can be applied to TW18-1 is estimated to range from 32 USgpm to 90 USgpm (Table 2). TW18-1 is positioned approximately 8.5 m and 13.0 m from the north and south end of the west abutment, respectively (Figure 1). Assuming an upper bound hydraulic conductivity and a pumping rate of 90 USgpm, the estimated artesian pressure reduction below the north end of the abutment would be approximately 8 m and below the south end of the abutment would be approximately 7 m (Table 2). If a lower bound hydraulic conductivity is assumed and a pumping rate of 32 USgpm applied to TW18-1, the same pressure reductions would be achieved, since the hydraulic conductivity and pumping rate are reduced proportionally. Accordingly, the analysis indicates that sustained independent use of Test Well TW18-1 as a production well could achieve 50% to 60% of the target pressure reduction below the west abutment, which is equivalent to a residual (i.e., remaining) artesian pressure of 5 m to 6 m below the west abutment. Page 4 of 9

5 Memorandum (cont d) Test Well Installation, Testing and Evaluation Project No.: VAN A0 March 20, 2018 Table 2. Modelled Bedrock Depressurization 1 Test Well TW18-1 New Production Well (South) New Production Well (North) PUMPING SCENARIO Hydraulic Conductivity 4 (m/s) Pumping Rate (USgpm) Drawdown Depth (m-bg) Well Depth (m-bg) Pumping Rate (USgpm) Drawdown Depth (m-bg) Minimum Well Depth (m-bg) Pumping Rate (USgpm) Drawdown Depth (m-bg) Minimum Well Depth (m-bg) Total Pumping Rate (USgpm) Residual Artesian Pressure 2 #1 #2 #3 #4 NOTES: 2.0 x to 6 m 6.1 x to 6 m 2.0 x x x x x x Bedrock depressurization target is 1 m below underside of west abutment 2 Assumes an initial 13 m pre-pumping artesian pressure measured at 1 m below underside of west abutment 3 Assumes sustained pumping for 7 days 4 Upper and lower bound values, per Table 1 Page 5 of 9

6 Memorandum (cont d) Test Well Installation, Testing and Evaluation Project No.: VAN A0 March 20, 2018 Scenario #2 One New Production Well Scenario #2 assumed that one new production well is constructed at a 6 m offset from the south end of the abutment cap along the foundation axis. Assuming an upper bound hydraulic conductivity, the target depressurization of 13 m is achieved below the entire abutment footprint after 7 days of sustained pumping at a rate of 155 USgpm (Table 2). The corresponding 7-day drawdown (upper bound) in the production well is estimated to be approximately 37 m-bg; therefore, a minimum production well depth of 38 m would be required to accommodate the drawdown. Assuming a lower bound hydraulic conductivity, the target depressurization of 13 m is achieved below the abutment after 7 days of sustained pumping at a rate of 60 USgpm (Table 2). The corresponding 7-day drawdown (lower bound) in the production well is estimated to be approximately 43 m; therefore, a minimum production well depth of 44 m would be required. Scenario #3 Production Well PW18-1 (TW18-1) and One New Production Well Scenario #3 assumed that Test Well TW18-1 is operated as a production well concurrently with a new production well constructed at a 6m offset from the south end of the abutment cap. Assuming an upper bound hydraulic conductivity, the target depressurization of 13 m is achieved below the abutment footprint after 7 days of sustained pumping at a rate of 70 USgpm from TW18-1 and 80 USgpm from the new production well (Table 2). The corresponding 7-day drawdown (upper bound) in the new production wells is estimated to be approximately 19 m-bg; therefore, a minimum production well depth of 20 m would be required to accommodate the drawdown. Assuming a lower bound hydraulic conductivity, the abutment depressurization target is achieved after 7 days of sustained pumping at rates of 23 USgpm from TW18-1 and 35 USgpm from the new production well (Table 2). The corresponding 7-day drawdown (lower bound) in the new production well is estimated to be approximately 25 m-bg; therefore, a minimum production well depth of 26 m would be required. Scenario #4 Two New Production Wells Scenario #4 assumed that two new production wells are constructed at a 6 m offset from the north and south ends of the abutment cap, along the foundation axis, and operated concurrently at the same pumping rate. Assuming an upper bound hydraulic conductivity, the target depressurization of 13 m is achieved below the abutment footprint after 7 days of sustained pumping at a combined rate of 130 USgpm (Table 2). The corresponding 7-day drawdown (upper bound) in both production wells is estimated to be approximately 14 m-bg; therefore, a minimum production well depth of 15 m would be required to accommodate the drawdown. Assuming a lower bound hydraulic conductivity, the 13 m depressurization target is achieved below the abutment after 7 days of sustained pumping at a combined rate of 50 USgpm (Table 2). The corresponding 7-day drawdown (lower bound) in both production wells is estimated to be approximately 17 m-bg; therefore, minimum production well depths of 18 m would be required. Page 6 of 9

7 Memorandum (cont d) Test Well Installation, Testing and Evaluation Project No.: VAN A0 March 23, DISCUSSION 3.1 Bedrock Depressurization Analysis and Modeling Analysis of test data from Test Well TW18-1 indicates that artesian bedrock pressure can be reduced through sustained withdrawal of groundwater from existing Test Well TW18-1 and/or new production wells and that a depressurization target equivalent to 1 m below the underside of the west abutment is feasible. Groundwater pumping rates to accomplish the required pressure reduction are predicted to range from approximately 50 USgpm, which is the lower bound value for two new production wells constructed in close proximity to the west abutment (Section 2.5), to approximately 155 USgpm, which is the upper bound value for one new production well located near the south end of the abutment (Table 2). These predicted values represent the initial rate of groundwater withdrawal required to achieve the depressurization within approximately 7 days. It is anticipated the reduced bedrock pressure can then be maintained with correspondingly lower pumping rates. Available measured and modeled static hydraulic heads are summarized in Table 3. A conservative hydraulic head increase of 3m to 4m above measured values has been assumed to account for seasonal high groundwater conditions. If hydraulic heads lower than the Table 3 values are assumed, the predicted pumping rates and drawdowns summarized in Table 2 will be correspondingly reduced. Table 3. Summary of Static Hydraulic Heads Location Pressure Head (m) Hydraulic Head (m-asl) Measurement BH17-02 (1) Pressure Gauge TW18-1 (1) Transducer Model Production Well (2) Model Monitoring Well (2) NOTES: 1 Reference level is 755 m 2 Includes seasonal increase of 3.4 to 4.4 m 3.2 Production and Monitoring Wells Proposed new production wells and any new monitoring wells (i.e., piezometers) must be constructed in compliance with Water Sustainability Act (WSA) and Groundwater Protection Regulation (GWPR) requirements. Given the confirmed flowing artesian conditions and relatively high artesian pressures, the installation, design and completion of production wells and piezometers must specifically consider mandatory control and decommissioning requirements. It is anticipated that at least two bedrock production wells would be operated to achieve the abutment area depressurization target. It is recommended a third contingency production well be constructed and equipped with a pumping assembly, as a back-up for the primary wells. If a primary production well either malfunctions or requires routine maintenance, the contingency production well could be placed on duty either prior to a scheduled maintenance event or in response to an unscheduled shut-down. Page 7 of 9

8 Memorandum (cont d) Test Well Installation, Testing and Evaluation Project No.: VAN A0 March 23, 2018 Required depths for new production wells are estimated to range from approximately 15 m for two news production wells installed in close proximity to the west abutment (Section 2.5) to approximately 44 m for one new production well located near the south end of the abutment (Table 2). These depths are based on modeled drawdown predictions after 7 days of pumping and an allowance for 1 m of pump submergence. 3.3 Pumping System Commissioning and Well Decommissioning It is recommended an aquifer pumping test be completed to evaluate production well function and effectiveness in depressurizing the west abutment area and also to inform contractor decisions regarding the location, depth and required pumping rates for any subsequent production wells. Project production wells (including TW18-1) and monitoring wells must be decommissioned in agreement with WSA and GWPR requirements, and requisite decommissioning reports prepared and submitted to the relevant Provincial Government Ministry. 3.4 Water Quality and Discharge Monitoring Laboratory analysis of groundwater quality samples has been completed and the resulting laboratory reports are being reviewed by Triton for compliance with FWAL Guidelines. Triton s review will identify groundwater treatment (if any) requirements prior to Project water being released to the local environment. This review process and findings are intended for current planning-stage decisions. Additional sampling of Project site water will be required intermittently during construction to confirm treatment system (if any) performance and discharge compliance. 4 LIMITATIONS The hydrogeological interpretations and opinions provided in this memorandum are based on the results of predictive models that are considered reasonable approximations of actual site conditions. Although the analytical models represent an idealized hydro-stratigraphic setting, ranged values are necessarily provided for primary model outputs, given the observed variability of the flow-pressure testing data and the potential for natural variation of any groundwater system. The data utilized and analytical approaches employed are considered appropriate for depressurization feasibility evaluation and determination of primary production well details. Hydraulic testing of new production wells, including a long-duration aquifer pumping test, will be required for construction dewatering system design purposes. Page 8 of 9

9

10 E CRK POST 5STR BARBED WIRE 760 PED N LIMIT OF TOPOGRAPHIC SURVEY C Inv Ø HSP Condition Poor 2P 758 Inv F WALPER021 COORD. NEW R/W N E WOOD POST 4STR BARBED WIRE AH17-02 C/F WEST ABUTMENT Inv PED 3STR BARBED WIRE GP AH Ø CSP BH17-02 F GP F 754 Inv WALPER025 TW WOOD POST 4STR BARBED WIRE WOOD PILINGS AH Ø m RIPRAP DP DP Pilings 752 METAL 0.25 m Ø 752 LOG F SHALE F 754 WALPER024 Post 2P Pilings BH17-01 Post 754 Ls Ɵs ELECTRIC FENCE DP WALPER '20" 0.25 m Ø WOOD DP ELECTRIC FENCE LOG 0.5 Ø m RIPRAP BRIDGE UTM N E AH17-01 AH STR BARBED WIRE E F/C N F/C Ls Ɵs 30 PAGE WIRE AND LOG FENCE PAGE WIRE FENCE 6 08'20" C/F COORD. NEW R/W N E LIMIT OF TOPOG 756 C TOWN F/C 8m SPRUCE POSTING PLAN PG LEGEND POSTING PLAN PG PED AUGERHOLE LOCATION F R c AD ARC Es " " RT 66 04' ' exp Services Inc. Ls Ɵs E N '56" MG DGS 752 MINISTRY OF TRANSPORTATION & INFRASTRUCTURE WALPER BRIDGE DAWSON CREEK, B.C. BOREHOLE LOCATION TEST WELL LOCATION PREVIOUS AUGERHOLE REFERENCE PLAN FROM STANTEC DATED BOREHOLE LOCATION PLAN DWS VAN A :500 FIGURE 1

11 TW mm (6') CASING CAP STICKUP 1.1m SOIL TYPE SAND & SILT SM REFERENCE GROUND LEVEL 300mm (12") CASING, DRIVEN CLAY CL GROUT 5.2m (17ft.) 200mm (8") CASING, DRIVEN SILTY CLAY & GRAVEL GC 7.7m (25.4ft.) 150mm (6") CASING, DRIVEN TO REFUSAL 9.3m (30.6ft.) SILTSTONE 150mm (6") OPEN HOLE, AIR ROTARY DRILL SANDSTONE 115mm (4.5") SLOTTED PVC PIPE EOH 18.3m (60ft.) NOTES: 1. DIMENSIONS BELOW GROUND UNLESS OTHERWISE INDICATED. PRESSURE READINGS CORRECTED TO GROUND UNLESS OTHERWISE INDICATED, TAKEN BY TRANSDUCER IN 150mm (6") CASING. 2. UNRESTRICTED ARTESIAN FLOW OBSERVED AT ABOUT 2 gpm AND 24 gpm IN 200mm (8") CASING (AFTER DRILLING) AND IN THE 150mm (6") OPEN HOLE, RESPECTIVELY. 3. STATIC WATER LEVEL = 6.6m (21.7ft.) ABOVE GROUND AFTER DRILLING THE 150mm (6") OPEN HOLE. 4. WELL INSTALLATION BY CARIBOO WATER WELLS OF PRINCE GEORGE, BC. 5. THE CASINGS WERE DRIVEN USING A PNEUMATIC HAMMER (TOP), AND ADVANCED AHEAD OF THE CLEANOUT INSIDE THE CASING USING AIR ROTARY DRILL AND TRICONE WALPER BRIDGE DAWSON CREEK, B.C. TEST WELL COMPLETION DETAILS SCHEMATIC VAN A0 MG DGS NTS FIGURE TW18-01

12 Project: Walper Bridge Location: Walper Bridge Prepared by: VAN A0 Datum: EXP Services Inc. Northing/Easting: , Logged by: DGS Reviewed by: DWS DEPTH (m) 0 DRILLING DETAILS S P T Elevation: 755 m Pocket Penetrometer Shear Strength (kpa) DYNAMIC CONE (BLOWS/300 mm) Natural Vane (KPa) Remold Vane (KPa) SPT "N" (BLOWS/300 mm) W P% W% W L% SAMPLE TYPE SAMPLE NO RECOVERY (%) SUMMARY LOG SOIL SYMBOL TOPSOIL Alignment: Station/Offset: Coordinates taken with GPS SOIL DESCRIPTION SAND & SILT, brownish grey, damp TS 0.3m Date(s) Drilled: to Driller: Curt Drill Make/Model: TH60 Drilling Method: Air Rotary CLASSIFICATION Drill Hole #: TW18-01 Drilling Company: Cariboo Water Wells COMMENTS TESTING Drillers Estimate {G % S % F %} WATER WELL ELEVATION (m) 1 SM SILTY CLAY, some sand, some gravel, dark olive grey, damp 1.83m CL Grout between 305mm and 203mm casing 5 305mm casing set at 5.18m MOT-SOIL-REV A0.GPJ MOT-DRAFT-REV2C.GDT 3/15/ Legend Sample Type: L#-Lab Sample A-Auger C-Core G-Grab V-Vane S-Split Spoon O-Odex (air rotary) W-Wash (mud return) T-Shelby Tube SILTY CLAY & GRAVEL, some sand, dark olive grey, wet SILTSTONE Legend Installation: Sand Drill Cuttings Grout Slotted Cement Slough 7.01m 8.23m Bentonite GC Piezometer 203mm casing set at 7.72m 152mm casing with drive shoe set at 9.3m Final Depth of Hole: 18.3 m Depth to Top of Rock: 8.2 m Page 1 of 2

13 Project: Walper Bridge Location: Walper Bridge Prepared by: VAN A0 Datum: EXP Services Inc. Northing/Easting: , Logged by: DGS Reviewed by: DWS DEPTH (m) 10 DRILLING DETAILS S P T Elevation: 755 m Pocket Penetrometer Shear Strength (kpa) DYNAMIC CONE (BLOWS/300 mm) Natural Vane (KPa) Remold Vane (KPa) SPT "N" (BLOWS/300 mm) W P% W% W L% SAMPLE TYPE SAMPLE NO RECOVERY (%) SUMMARY LOG SOIL SYMBOL Alignment: Station/Offset: Coordinates taken with GPS SOIL DESCRIPTION SILTSTONE (continued) Date(s) Drilled: to Driller: Curt Drill Make/Model: TH60 Drilling Method: Air Rotary CLASSIFICATION Drill Hole #: TW18-01 Drilling Company: Cariboo Water Wells COMMENTS TESTING Drillers Estimate {G % S % F %} WATER WELL ELEVATION (m) SI SANDSTONE, fine grained 15.24m 115mm ID slotted PVC pipe SS MOT-SOIL-REV A0.GPJ MOT-DRAFT-REV2C.GDT 3/15/ Legend Sample Type: L#-Lab Sample A-Auger C-Core G-Grab V-Vane S-Split Spoon O-Odex (air rotary) W-Wash (mud return) T-Shelby Tube Logged based on cuttings return and drill action and referenced against BH17-02, core hole log nearby. Legend Installation: Sand Drill Cuttings Grout Slotted Cement Slough 18.29m Bentonite Piezometer Final Depth of Hole: 18.3 m Depth to Top of Rock: 8.2 m Page 2 of 2

14 TEST WELL TW18-1 FLOW AND PRESSURE MONITORING March 8-9, Test #1 Test # m 6.0 Test #3 Remove Transducer from 6-Inch Casing Automated Transducer Measurements in 6-Inch Production Casing Inch Casing Valve Opened :00 08:00 09:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00 00:00 01:00 02:00 03:00 04:00 05:00 06:00 07:00 08:00 Groundwater Level (metres above ground surface) Pressure Gauge on 8-Inch Surface Casing Install Transducer in 6-Inch Casing March 8, 2018 March 9, 2018 Time (Hour) NOTES - 1) Automated pressure transducer data collected from Test Well TW18-1 at 30-second frequency. NOTES - 2) Datum is ground surface at Test Well TW18-1. NOTES - 3) Dial-type pressure gauge attached to top of 8-inch diameter casing. NOTES - 4) Dashed orange line is linear trend through 8-inch casing pressure gauge during Test #1. Project No. VAN A0 Drawn MDM Reviewed Date Mar PROJECT WALPER BRIDGE REPLACEMENT TEST WELL INSTALLATION, TESTING AND EVALUATION Test Well TW18-1 Flow and Pressure Monitoring Fig. 2

15 DRAWDOWN VERSUS TIME TEST #1, #2 AND # USgpm (0.1 ft) 1.91 USgpm (0.6 ft) USgpm (2.4 ft) 6.96 USgpm (3.6 ft) USgpm (4.2 ft) DRAWDOWN - feet 10 3 DRAWDOWN - metres USgpm (17.4 ft) 21.8 USgpm (17.4 ft) TIME FROM TEST START - MINUTES TEST #1 6" Production Casing Flow Through 1" Discharge - Progressively Opened Valve TEST #2 6" Production Casing Flow Through 2" Discharge - Fully Open TEST #3 6" Production Casing Flow Through 2" Discharge - Fully Open Project No. VAN A0 Drawn MDM Reviewed Date Mar PROJECT WALPER BRIDGE REPLACEMENT TEST WELL INSTALLATION, TESTING AND EVALUATION Drawdown Versus Flow - Test #1, #2 and #3 Fig. 3