Reference No. T041050a2. Mississauga, August 12, 2014

Transcription

1 Reference No. T041050a2 Mississauga, August 12, 2014 Mr. Daniel Castiglione Director of Development First Gulf Corporation 3751 Victoria Park Avenue Toronto, Ontario M1W 3Z4 Subject: In-Situ Permeability Testing Proposed Office Building 514 South Service Road East, Oakville, Ontario Dear Mr. Castiglione; As requested by First Gulf Corporation, Inspec-Sol Inc. (Inspec-Sol) is pleased to present this letter that summarizes our findings of insitu permeability testing carried out at two selected locations at the proposed office building development, at 514 South Service Road East, in Oakville, Ontario. The purpose of testing is to provide permeability/percolation estimates of the shallow soils at the site for stormwater management design. The soil permeability was carried out at two select locations identified as GP1 located on the west side of the site and GP2 located at the south side as shown on the attached figure. 1.0 PERMEABILITY TEST METHOD AND FIELD PROCEDURES The insitu permeability test was carried out using a Guelph Permeameter (GP) in accordance with ASTM D5126. The Guelph permeameter measures permeability in the vadose zone above the water table, where the soil is unsaturated. Steady flow from the unit produces a small inner saturated zone adjacent to the test holes, encased within a larger outer wetted, but unsaturated volume. As a consequence, combined saturated-unsaturated flow occurs. The GP method measures the steady-state rate necessary to maintain a constant depth of water in an uncased

2 cylindrical borehole above the water table. calculated using an approximate analytical solution. The field saturated hydraulic conductivity is A summary of field procedures carried out is presented below: Excavate a cylindrical borehole to the desired depth in the material to be tested; Fill the permeameter with liquid and insert it in the well; Start the permeameter by raising the air-inlet tube out of the outlet port; Set the desired head (H) level by adjusting the height of the air-inlet tube; Monitor the rate of fall of the water surface in the reservoir until a steady rate, r, is attained; The field work was carried by Inspec-Sol staff on July 30, Two infiltration tests were conducted using the Guelph Pemeameter, within the proposed subdivision area. The test locations are shown on Figure 1. The test holes were prepared by using an auger that extended to approximately 0.4 m below grade. Field classification of the shallow soils at the test hole locations indicated silty clay to clayey silt with some sand and gravel, which was consistent with the soils identified during our geotechnical investigation previously carried out at the Site, dated July 9, HYDRAULIC CONDUCTIVITY AND APPROXIMATE INFILTRATION RATE The hydraulic conductivity measured in the unsaturated (vadose) zone is referred to as the field-saturated hydraulic conductivity (Kfs) (Reynolds et al, 1983). The Guelph Permeameter method measures the steady-state flow rate (Q) necessary to maintain a constant depth of water (H) in an uncased borehole. Kfs is then calculated from Q and H using the analytical solutions presented on Appendix A (after Reynolds et al., 1985). The analytical solution input parameters include the following: reservoir cross sectional area; water height; borehole radius; soil texture; and steady state rate of water level change. 2 Permeability Test, 514 South Service Road East, Oakville Ref. No. : T041050a2 August 12, 2014

3 An in situ infiltration rate can be estimated using the empirical relationship between hydraulic conductivity and infiltration rate (Ontario Ministry of Municipal Affairs and Housing, 1997). The calculation of approximate infiltration rate is presented in Appendix A. Based on the results of the permeability testing, the soil hydraulic conductivity (Kfs), infiltration rate, and percolation time (T) at the three test locations are as follows: GP ID Approximate Infiltration Rate (mm/h) Percolation Rate (min/cm) Kfs (cm /s) E E The test result at GP-1 is considered to be low permeability and the result at GP-2 is considered to be low-medium permeability, and therefore are not considered conducive for effective stormwater infiltration. We trust that this summary letter is to your satisfaction and meets your present requirements. Please do not hesitate to contact us, should any question arise. Yours very truly, INSPEC-SOL INC. Karl Roechner, M.A.Sc., P.Eng. KR/sm Enclosures: Figure 1 Insitu Permeability Test Location Plan Appendix A Analysis Results Permeability Test 514 South Service Road East, Oakville 3 Ref. No. : T041050a2 August 11, 2014

4 Figure Insitu Permeability Test Location Plan Figure 1

5

6 Appendix A Analysis Results

7 Rate of Water Level Change in Permeameter (cm/min) FIGURE 1A GUELPH PERMEAMETER TEST ANALYSIS SOUTH SERVICE ROAD First Gulf 0.50 West area m bgs Water Level in Permeameter (cm) Time (min) hydraulic conductivity, field saturated (1) (K fs ) = 2.63E-07 cm/s K fs approximate infiltration rate (2) = mm/h 11 1 = 9 mm/h percolation time = (infiltration rate) -1 x (60 min/hr) X (10 mm/cm) min/cm = 64 min/cm Notes: (1) see Figure C2 for calculation of K fs (2) Ontario Ministry of Municipal Affairs and Housing (OMMAH) Supplementary Guidelines to Ontario Building Code SG-6 Percolations Times and Soil Descriptions. Toronto, Ontario

8 FIGURE 1B GUELPH PERMEAMETER TEST ANALYSIS SOUTH SERVICE ROAD First Gulf Single Head Method (1) Single Head Method (2) Input Result Average Reservoir Cross-sectional area in cm 2 Reservoir Cross-sectional area in cm 2 K fs = 2.63E-07 cm/sec (enter "35.22" for Combined and "2.16" for Inner reservoir): 2.16 (enter "35.22" for Combined and "2.16" for Inner reservoir): E-05 cm/min Enter water Head Height ("H" in cm): 5 Enter water Head Height ("H" in cm): E-09 m/s Enter the Borehole Radius ("a" in cm): 3 Enter the Borehole Radius ("a" in cm): E-06 inch/min 1.04E-07 inch/sec Enter the soil texture-structure category (enter one of the below numbers): 1 Enter the soil texture-structure category (enter one of the below numbers): 1 Φ m = 2.63E-05 cm 2 /min Steady State Rate of Water Level Change ("R" in cm/min): Steady State Rate of Water Level Change ("R" in cm/min): Res Type 2.16 Res Type 2.16 H 5 H 5 a 3 α*= 0.01 cm -1 a 3 α*= 0.01 cm -1 H/a H/a a* 0.01 C = a* 0.01 C = C Q = C Q = C C C K fs = 2.63E-07 cm/sec C K fs = 2.63E-07 cm/sec C E-05 cm/min C E-05 cm/min C E-09 m/sec C E-09 m/ses R E-06 inch/min R E-06 inch/min Q E-07 inch/sec Q E-07 inch/sec pi pi Φ m = 2.63E-05 cm 2 /min Φ m = 2.63E-05 cm 2 /min (Adapted from "Guelph Permeameter Calculations" spreadsheet provided by equipment manufacturer, Soilmoisture Equipment Corp.)

9 Rate of Water Level Change in Permeameter (cm/min) FIGURE 2A GUELPH PERMEAMETER TEST ANALYSIS SOUTH SERVICE ROAD First Gulf 0.50 South-central area m bgs Water Level in Permeameter (cm) Time (min) hydraulic conductivity, field saturated (1) (K fs ) = 2.72E-06 cm/s K fs approximate infiltration rate (2) = mm/h 11 1 = 18 mm/h percolation time = (infiltration rate) -1 x (60 min/hr) X (10 mm/cm) min/cm = 34 min/cm Notes: (1) see Figure C2 for calculation of K fs (2) Ontario Ministry of Municipal Affairs and Housing (OMMAH) Supplementary Guidelines to Ontario Building Code SG-6 Percolations Times and Soil Descriptions. Toronto, Ontario

10 FIGURE 2B GUELPH PERMEAMETER TEST ANALYSIS SOUTH SERVICE ROAD First Gulf Single Head Method (1) Single Head Method (2) Input Result Average Reservoir Cross-sectional area in cm 2 Reservoir Cross-sectional area in cm 2 K fs = 2.72E-06 cm/sec (enter "35.22" for Combined and "2.16" for Inner reservoir): 2.16 (enter "35.22" for Combined and "2.16" for Inner reservoir): E-04 cm/min Enter water Head Height ("H" in cm): 10 Enter water Head Height ("H" in cm): E-08 m/s Enter the Borehole Radius ("a" in cm): 3 Enter the Borehole Radius ("a" in cm): E-05 inch/min 1.07E-06 inch/sec Enter the soil texture-structure category (enter one of the below numbers): 1 Enter the soil texture-structure category (enter one of the below numbers): 1 Φ m = 2.72E-04 cm 2 /min Steady State Rate of Water Level Change ("R" in cm/min): Steady State Rate of Water Level Change ("R" in cm/min): Res Type 2.16 Res Type 2.16 H 10 H 10 a 3 α*= 0.01 cm -1 a 3 α*= 0.01 cm -1 H/a H/a a* 0.01 C = a* 0.01 C = C Q = C Q = C C C K fs = 2.72E-06 cm/sec C K fs = 2.72E-06 cm/sec C E-04 cm/min C E-04 cm/min C E-08 m/sec C E-08 m/ses R E-05 inch/min R E-05 inch/min Q E-06 inch/sec Q E-06 inch/sec pi pi Φ m = 2.72E-04 cm 2 /min Φ m = 2.72E-04 cm 2 /min (Adapted from "Guelph Permeameter Calculations" spreadsheet provided by equipment manufacturer, Soilmoisture Equipment Corp.)