GEOTECHNICAL INVESTIGATION REPORT

Transcription

1 SHAD 髂髂 July 15, 2011 Attention: Re: 獒獒獒獒 Reference No. : T11284 Royal Park Homes and Century Grove Homes c/o Urbantech Consulting 25 Royal Crest Court, Unit 201 Markham, Ontario L3R 9X4 Dear Mr. Leighton, Mr. David Leighton, CET President > GEOTECHNICAL INVESTIGATION REPORT PROPOSED CHANNEL, STORMWATER MANAGEMENT PONDS & 3 RD SIDEROAD SERVICING MILTON HEIGHTS 3 RD SIDEROAD & TREMAINE ROAD MILTON, ONTARIO Please find enclosed the Geotechnical Investigation Report prepared for the above captioned project. Should you have any questions or require any clarifications, please do not hesitate to contact our office. We thank you for giving us this opportunity to be of service to you. Sincerely, Shad & Associates Inc. Houshang Shad, Ph.D., P. Eng. Principal & AOCIATES INC. GEOTECHNICAL, ENVIRONMENTAL AND MATERIALS CONSULTING ENGINEERS 83 Citation Drive, Unit 9 Vaughan, Ontario, L4K 2Z6 Tel: (905) Fax: (905)

2 GEOTECHNICAL INVESTIGATION REPORT PROPOSED CHANNEL, STORMWATER MANAGEMENT PONDS & 3 RD SIDEROAD SERVICING MILTON HEIGHTS 3 RD SIDEROAD & TREMAINE ROAD MILTON, ONTARIO Submitted to: Royal Park Homes & Century Grove Homes c/o Urbantech Consulting 25 Royal Crest Court, Unit 201 Markham, Ontario L3R 9X4 Attention: Mr. David Leighton, CET Submitted by: Shad & Associates Inc. 83 Citation Drive, Unit 9 Vaughan, Ontario, L1K 2Z6 Canada Tel: (905) Fax: (905) July 15, 2011 T11284

3 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, 2011 TABLE OF CONTENTS 1.0 INTRODUCTION INVESTIGATION PROCEDURES SUB-SURFACE CONDITIONS Proposed Channel Topsoil and Ploughed Fill Silty Clay / Clayey Silt Till Silty Sand to Sandy Silt and Silt Clayey Silt Groundwater Conditions Proposed SWM Pond S Proposed Stormwater Management S Proposed 3 RD Sideroad Servicing DISCUION AND RECOMMENDATIONS Proposed Channel Channel Excavation and Construction Dewatering Channel Construction Culvert Foundations Slope Stability Analysis Proposed Stormwater Management Pond S Slope Stability Analysis Pond Excavation and Construction Dewatering Pond Construction Concrete Headwalls Proposed Stormwater Management Pond S Slope Stability Analysis Pond Excavation and Construction Dewatering Pond Construction Concrete Headwalls Proposed Servicing for 3 rd Sideroad Trenching Bedding Backfill Pavement Thickness Engineered Fill CLOSURE...25 STATEMENT OF LIMITATIONS FIGURES Figure 1 Figure 2 Site Location Plan Borehole Location Plan / Page 1

4 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, 2011 Enclosure A: Record of Boreholes & Test Pits Explanation of Borehole Logs Enclosure B: Soil Profiles ENCLOSURES Enclosure C: Slope Stability Analysis Results for the Proposed Channel & Stormwater Management Ponds / Page 2

5 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, INTRODUCTION As requested, Shad & Associates Inc. has prepared a geotechnical investigation report for the proposed channel, Stormwater Management Ponds S43 and S44 as well as for servicing of 3 rd Sideroad from Milton Heights Crescent to Peru Road as part of Milton Heights development, in Milton, Ontario, as shown in Figure 1. The purpose of this geotechnical investigation was to obtain information about the subsurface conditions at the site by means of a number of boreholes and test pits. Based on our interpretation of the data obtained, recommendations are provided on the geotechnical aspects of the proposed construction. It should be noted that the environmental aspects of this site are beyond our current scope of work. We wish to mention that concurrent with our geotechnical investigation at the property, the hydrogeological condition of the site was also being assessed jointly by R.J. Burnside ( Burnside ) and AMEC. Their report should be referenced for more information. This report contains the findings of our geotechnical investigation, together with our recommendations and comments. These recommendations and comments are based on factual information and are intended only for use by the design engineer. We recommend on-going liaison with Shad & Associates Inc. during the design and construction phases of the project to ensure that the recommendations provided in this report are applicable and/or correctly interpreted and implemented. Also, any queries concerning the geotechnical aspects of the proposed project should be directed to Shad & Associates Inc. for further elaboration and/or clarification. 2.0 INVESTIGATION PROCEDURES The fieldwork for this investigation was carried out during the period of June 16, 17, 20, 27 and July 5, 2011 and it consisted of drilling and sampling altogether thirteen boreholes and excavating seven test pits at the locations shown on the Borehole & Test Pit Location Plan, Figure 2. The depth of the boreholes ranged from about 4.3 m to 8.8 m and those for the test pits ranged from approximately 4.1 to 5.9 m below existing ground surface. All the boreholes were equipped with piezometers or nested monitoring wells (as requested by the project hydrogeologists). The borehole and test pit locations were staked out in the field by Holding Jones Vanderveen Surveying Limited, O.L.S., who also provided us with their geodetic ground surface elevations. The boreholes were advanced using solid or hollow stem continuous flight augers, with a trackmounted power auger drilling rig, under the full-time supervision of experienced geotechnical personnel from our office. In the boreholes, soil samples were obtained at regular intervals / Page 3

6 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, 2011 (0.75 m) in accordance with Standard Penetration Test (SPT) procedures, as specified by ASTM D1586 Standard. This consists of freely dropping a 63.5 kg (140 lbs) hammer a vertical distance of 0.76 m (30 inches) to drive a 51 mm (2 inches) diameter o.d. split-barrel (split spoon) sampler into the ground. The number of blows of the hammer required to drive the sampler into the relatively undisturbed ground by a vertical distance of 0.30 m (12 inches) is recorded as the SPT N value of the soil and this gives an indication of the consistency or the relative density of the soil deposit. The test pits were excavated by a John Deere 992 Excavator provided by the Client and they were supervised by senior staff from Shad. During the excavation of Test Pits 1, 2 and 4, senior staff from Burnside and AMEC were also present. All collected soil samples were transported to our Soils Laboratory in sealed containers for further examination and laboratory testing. Laboratory tests, consisting of natural moisture content determinations, Atterberg Limits Tests and Gradation analysis were performed on selected samples. The results of the in-situ and laboratory tests are presented on the corresponding Record of Borehole Sheets, Enclosure A. It should be noted that samples obtained during this investigation will be stored in our Soils Laboratory for three months and will be disposed thereafter. 3.0 SUB-SURFACE CONDITIONS The stratigraphic units and groundwater conditions for the different aspects of the development are discussed separately in the following sections. For more detailed information, reference should be made to the Record of Borehole Sheets. 3.1 Proposed Channel (Boreholes BH1 to 7 & 13A) Topsoil and Ploughed Fill As the boreholes were drilled within a ploughed field, they all encountered a surficial topsoil and/or ploughed/disturbed fill generally extending down to depths ranging from 0.3 to 0.7 m below existing ground surface. However, at the location of Boreholes 3 and 7, these layers were found to be thicker, extending down to 1.4 m and 1.5m, respectively. It should however be noted that the thickness and quality of topsoil and fill can vary in between and beyond the borehole locations, and therefore, we recommend that allowance be made for possible variations when making estimates. / Page 4

7 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, Silty Clay / Clayey Silt Till This is the dominant soil type at the site and was encountered at all borehole locations extending from below the surficial topsoil and/or ploughed fill to depths ranging from 0.7 m at Borehole 1 to at least 5.8 m below existing grade in Borehole 13A. Occasional to some sand and silt seams were also noted in some boreholes. This glacial deposit was again contacted at lower elevations at most borehole locations. Standard Penetration Tests were performed within the silty clay / clayey silt till deposit and the recorded N -values were found to range widely, generally from 10 to 29 with occasional lower values of down to 5 blows/0.3 m (measured immediately below the topsoil and/or ploughed fill) and higher values of up to 42 blows/0.3 m. Considering these results as well as visual and tactile examination of the recovered soil samples, the silty clay / clayey silt till is firm to hard but generally stiff to very stiff. Representative samples from this deposit were also tested for Natural Moisture Content and the results were found to predominantly range from 8 to 18%, indicating a damp condition. However, occasional higher values of up to 22% were also measured within the organic stained portion of the till deposit, contacted immediately below the topsoil/ploughed fill. Two representative samples from the fine grained glacial deposit were tested in the laboratory for gradation. The results are presented on the appropriate Borehole Log sheets and are summarized below: Gravel: 2 to 3% Sand: 8 to 12% Silt: 57 to 59% Clay: 29 to 30% It should be noted that due to their formation, occasional cobbles and/or boulders should always be expected with the glacial deposit Silty Sand to Sandy Silt and Silt Interbedded in the cohesive clayey deposits, all boreholes encountered a basically cohesionless to occasionally slightly cohesive deposit which ranged in composition from silty sand to sandy silt to silt with trace to some clay. These deposits were contacted at a higher Elevation of m in Borehole 1, dropping in a west to east direction to Elevation m in Borehole 7. At Borehole 13A, only a 0.3 m thick silt interbedding was contacted at about Elevation m. The measured SPT N -values within the silty sand, sandy silty and silt deposits were found to generally range from 9 to 24 blows/0.3 m, indicating a loose to compact but generally compact / Page 5

8 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, 2011 relative density. However, a lower value of 1 blow/0.3 m was also measured in Borehole 2, which is believed to be due to water effect. Gradation analysis tests were performed on samples from the silty sand and silt layers and the results are summarized below: Silty Sand Gravel: 0% Sand: 63% Silt: 35% Clay: 2% Silt, some clay Gravel: 0% Sand: 7% Silt: 78% Clay: 15% Samples from silty sand, sandy silt and silt were also tested for Natural Moisture content and the results were found to range from 17 to 20%, 19% and 16 to 24%, respectively. Considering these results as well as the visual and tactile examination of the recovered soil samples, these deposits were found to be generally moist to wet Clayey Silt Clayey Silt was encountered at Boreholes 1 and 2, extending from 3.6 to 4.4 m and 3.9 m to borehole completion at 5.0 m, respectively. The clayey deposit was noted to be firm to stiff and moist to wet with recorded N -values of 5 to 12 blows/0.3 m penetration and measured moisture content values of 19 to 25% Groundwater Conditions Groundwater conditions were monitored during and upon the completion of drilling as well as by installing standpipe piezometers or nested monitoring wells in all boreholes. The results are summarized below in Table 1. / Page 6

9 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, 2011 Borehole BH 1 Shallow Deep BH 2 Shallow Deep BH 3 Shallow Deep BH 4 Shallow Deep BH 5 Shallow Deep BH 6 Shallow Deep BH 7 Shallow Deep Table 1: Measured Groundwater Data along Proposed Channel Ground Surface Elevation (m) Groundwater Level Upon Borehole Completion (m) m 4.6 m (El m) m 4.6 m (El m) m Dry m Dry m 7.5 m (El m) m Dry Groundwater Level Measured In Well/Piezometer on June 27, m (El m) 0.0 m (El m) 0.5 m (El m) 0.4 m (El m) 0.4 m (El m) 0.8 m (El m) 0.1 m (El m) 0.0 m (El m) 0.1 m (El m) 0.7 m (El m) 0.9 m (El m) 2.8 m (El m) Groundwater Level Measured In Well/Piezometer on July 5, m (El m) 0.2 m (El m) 0.5 m (El m) 0.6 m (El m) 0.6 m (El m) 0.9 m (El m) 0.2 m (El m) 0.6 m (El m) 0.5 m (El m) 0.6 m (El m) 0.3 m (El m) 0.6 m (El m) m Dry Dry 0.1 m (El m) 3.8 m (El m) 0.0 (El m) BH 13A m Dry 0.4 m (El m) 0.5 m (El m) Considering the above information, and the soil color change from brown to grey, we are of the opinion that the silty sand to sandy silt to silt layers and/or seams are under some artesian conditions. It should also be pointed out that the groundwater at the site would fluctuate seasonally and can be expected to be somewhat higher during the spring months and in response to major weather events. / Page 7

10 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, Proposed SWM Pond S43 (Boreholes 5, 6 and 13A) Considering the subsurface conditions encountered at Boreholes 5, 6 and 13A, located in close vicinity to SWM Pond S43, below a surfical topsoil and/or ploughed fill, extending down to about 0.7 m, the site is predominantly underlain by silty clay / clayey silt till. However, silt and/or sandy silt layers or interbeddings were also encountered at all three borehole locations at Elevations m, m and m, respectively. A gradation analysis was performed on a clayey silt till deposit and the results are summarized below: Gravel: 2% Sand: 12% Silt: 57% Clay: 29% Standard Penetration Tests were performed in the boreholes and the recorded N -values within the silty clay / clayey silt till were found to range widely from 10 to 42 blows/0.3 m penetration, indicating a stiff to hard, but generally very stiff consistency. Samples from the clayey till deposit were also tested for moisture content and the results were found to range from 8 to 16%, with a higher value of 22% measured immediately below the fill layer in Borehole 5. Considering these results, the silty clay / clayey silt till is generally damp. The measured N -values within the silt and sandy silt ranged from 10 to 14 blows/0.3 m penetration, indicating a compact relative density. Samples collected from these layers were also tested for Natural Moisture Content and the results were found to range from 17 to 24%. Based on these results as well as the visual and tactile examination of the recovered soil samples, the silt and sandy silt is generally moist and occasionally wet. Groundwater conditions at the proposed SWM Pond S43 were monitored during and upon the completion of drilling as well as by installing nested wells in Boreholes 5 and 6 as well as a standpipe piezometer in Borehole 13A. The results are summarized below in Table 2. Borehole BH 5 Shallow Deep BH 6 Shallow Deep Table 2: Measured Groundwater Data for the Proposed SWM Pond S43 Ground Surface Elevation (m) Groundwater Level Upon Borehole Completion (m) m 7.5 m (El m) Groundwater Level Measured In Well/Piezometer on June 27, m (El m) 0.7 m (El m) Groundwater Level Measured In Well/Piezometer on July 5, m (El m) 0.6 m (El m) m Dry 0.9 m(el m) 2.8 m (El m) 0.3 m (El m) 0.6 m (El m) BH 13A m Dry 0.4 m (El m) 0.5 m (El m) / Page 8

11 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, 2011 Considering the above information, and the soil color change from brown to grey, we are of the opinion that the sandy silt to silt layers and/or seams are under some artesian conditions. It should however be pointed out that the groundwater at the site would fluctuate seasonally and can be expected to be somewhat higher during the spring months and in response to major weather events. 3.3 Proposed Stormwater Management S44 (Boreholes 8 and 9) Considering the subsurface conditions encountered at Boreholes 8 and 9, located within the pond footprint, below a surficial topsoil and/or ploughed fill, extending down to about 0.7 m, the site is predominantly underlain by a silty clay / clayey silt glacial till deposit. However, a medium sand layer was also contacted near the surface, immediately below the fill in Borehole 9. The recorded N -values within the silty clay / clayey silt till were found to range widely from 11 to 47 blows/0.3 m penetration, indicating a stiff to hard, but generally very stiff to hard consistency. Samples from the clayey till deposit were also tested for natural moisture content and the results were found to range from 6 to 15%. Considering these as well as visual and tactile examination of the recovered soil samples, the silty clay / clayey silt till is generally damp. Atterberg Limits tests were also performed on a representative sample from this deposit and the results are summarized below: LL: 30% PL: 19% PI: 11% The results are indicative of low plasticity clays. The medium sand deposit contacted below the fill layer in Borehole 9 was found to be in a compact and moist state. The recorded N -value was 22 blows/0.3 m and the measured moisture content was 11%. Groundwater conditions at the proposed SWM Pond S44 were monitored during and upon the completion of drilling as well as by installing nested wells in each borehole. The results are summarized below in Table 3. / Page 9

12 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, 2011 Table 3: Measured Groundwater Data for the Proposed SWM Pond S44 Borehole BH 8 Shallow Deep BH 9 Shallow Deep Ground Surface Elevation (m) m Dry Groundwater Level Upon Borehole Completion (m) m 5.3 m (El m) Groundwater Level Measured In Well/Piezometer on June 27, 2011 Dry Dry 0.7 m(el m) 0.1 m (El m) Groundwater Level Measured In Well/Piezometer on July 5, 2011 Dry 6.6 m (El m) 0.0 m (El m) 1.0 m (El m) Considering the above information, and the soil color change from brown to grey, we are of the opinion that some artesian condition is present in the vicinity of Borehole 9. It should however be pointed out that the groundwater at the site would fluctuate seasonally and can be expected to be somewhat higher during the spring months and in response to major weather events. 3.4 Proposed 3 RD Sideroad Servicing (Boreholes 10A to 13A) Considering the subsurface conditions encountered at Boreholes 10A to 13A drilled along the alignment, north of the existing road, below the pavement structure and ploughed fill in Borehole 10A and the surfical topsoil and ploughed fill in the remaining borehole locations, extending to depths ranging from about 0.6 m to 0.9 m, the site is predominantly underlain by a silty clay/clayey silt till deposit. However, occasional interbeddings of silt and silty sand were also encountered at the site. Some clayey silt was also contacted near the completion of Boreholes 10A (extending from about 5.2 to 8.3 m below existing grade) and 11A (below a depth of about 7.8 m). Standard Penetration Tests were performed within the silty clay/clayey silt till and they resulted in N -values ranging widely from 10 to 45 blows/0.3 m penetration, indicating a stiff to hard but generally very stiff to hard consistency. Samples from this deposit were also tested for moisture content and the results were found to range from 5 to 18%. Considering these results as well as the visual and tactile examination of the recovered samples, the silty clay/clayey silt till is generally damp. The characteristics of a representative sample from the silty clay/clayey silt till deposit was further analysed by carrying out gradation and Atterberg Limits tests. The results are summarized below: Gravel: 1% Sand: 11% Silt: 63% / Page 10

13 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, 2011 Clay: 25% LL: 30% Pl: 19% PI: 11% The Atterberg Limits results are indicative of low plasticity clays. The silt to silty sand interbedding layers encountered in Boreholes 11A to 13A, were found to be compact to dense and moist with recorded N -values of 18 to 45 blows/0.3 m and measured moisture content values of 17 to 21%. A gradation analysis was performed on a sample collected from the silty layer in Borehole 11A and the following results were obtained: Gravel: 0% Sand: 8% Silt: 73% Clay: 19% The clayey silt layer encountered at lower elevations in Borehole 10A and 11A were noted to be moist (with measured moisture content values of 19 to 25%) but firm to stiff in Borehole 10A (with measured N -values of 6 to 9 blows/0.3 m) and very stiff in Borehole 11A (with a recorded N -value of 22 blows/0.3m). It should be noted that due to their formation, occasional cobbles and/or boulders should always be expected with the glacial deposit. Groundwater conditions at the boreholes drilled for the proposed road servicing were monitored during and upon the completion of our drilling as well as by installing standpipe piezometers in each of the boreholes. The results are summarized below in Table 4. Borehole Table 4: Measured Groundwater Data for Proposed 3 RD Sideroad Servicing Ground Surface Elevation (m) Groundwater Level Upon Borehole Completion (m) Groundwater Level Measured In Piezometer on June 27, 2011 Groundwater Level Measured In Piezometer on July 7, 2011 BH 10A m 7.6 m (El m) Flowing 0.1 m (El m) BH 11A m 7.4 m (El m) 0.0 m (El m) +1.5 m (El m) BH 12A m 6.5 m (El m) 0.0 m (El m) +1.6 m (El m) BH 13A m Dry 0.4 m (El m) 0.5 m (El m) Considering the above information and the soil color change from brown to grey, the site is under some artesian conditions. It should however be pointed out that the groundwater at the site would fluctuate seasonally and can be expected to be somewhat higher during the spring months and in response to major weather events. / Page 11

14 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, DISCUION AND RECOMMENDATIONS 4.1 Proposed Channel (Boreholes 1 to 7, 13A & Test Pits 1 to 6) According to the information provided to us by Urbantech Consulting (Grading Concept, Figure 2, dated March 2011), the channel identified as NW-2-G1 will commence near the northwest end of the site at an invert elevation of m, running along the north and then east boundaries and it will connect to the existing Channel NW-2-G1 located south of the 3 rd Sideroad. Near its termination, the proposed channel will have an invert elevation of m. Along its alignment, the proposed channel will pass under the future Tremaine Rd through a 105 m long culvert. Boreholes 1 to 7, 13A and Test Pits 1 to 6 were located along the proposed channel alignment. Considering the ground surface elevations at the boreholes and test pits and the proposed channel inverts, the channel will predominantly occur in cut. Some engineered fill will however be required for the channel wall. The subsurface conditions encountered at Boreholes 1 to 7 and 13A are summarized in the soil profile presented in Drawing No. 1 of Enclosure B. The proposed channel invert is also identified on the drawing. Considering this, apart from part of its initial north leg that will occur within the loose to compact silty sand to silt, the remainder of the channel should generally be formed in a firm to hard but generally stiff to very stiff silty clay/clayey silt till. Furthermore, the boreholes have shown that the silty sand and silt layers are under some artesian conditions. In order to confirm excavate-ability and groundwater conditions, six large test pits (i.e., TP 1 to 6) were excavated to well below the proposed channel invert and they were left open for periods ranging from 0.5 hr to 1 hr and 40 minutes. During this time, only minor seepage was noticed from the silt and silty sand contacted at the TP 1 and 2 excavated near the north part of the channel, and the remainder were found to be dry. It should however be noted that some surface run-off was also noticed from TP6 excavated near channel termination, close to the existing Channel NW-2-G Channel Excavation and Construction Dewatering Considering the existing and proposed grades as well as the subsurface conditions encountered at Boreholes 1 to 7 and 13A, as well as Test Pits TP1 to 6, below the surfical topsoil and ploughed fill, the excavation for the channel would predominantly occur in a firm to hard, but generally stiff to very stiff silty clay/clayey silt till. However, near its commencement, some loose to compact silty sand and silt will also be contacted. All excavations should be carried out in accordance with the Ontario Health and Safety Regulations. The soils to be excavated can be classified as follows: Topsoil and Ploughed Fill Type 3 Loose to Compact Silty Sand, Silt (above groundwater) Type 3 / Page 12

15 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, 2011 Firm to Stiff Silty Clay/Clayey Silt Till Type 3 Very Stiff to Hard Silty Clay/Clayey Silt Till Type 2 Accordingly, a side slope of 1H:1V is required for excavations in accordance with the Ontario Health and Safety Regulations. However, in Type 2 soils, the bottom 1.2 m of excavations within the very stiff to hard silty clay/clayey silt till, could be kept vertical. Also near the surface and below the groundwater level within the silty sand and silt deposits, flatter slopes may be required. Stockpiles of excavated materials should be kept at least 5.0 m from the edge of the excavation to avoid slope instability. Care should also be taken to avoid overloading of any underground services/structures by stockpiles. During excavation, minor seepage is expected from the firm to hard silty clay/clayey silt till and this should be manageable by filtered sump pumps, if required. However, increased seepage should be expected when excavating the silty sand and silt layers. However, considering the amount of seepage noted at the test pits, we are of the opinion that the seepage should still be manageable with increased number of sumps, if required. We request this to be confirmed by the project hydrogeologits Channel Construction Considering the highwater level and the presence of silty sand and silt deposits at or close to the channel invert north of Borehole 5, some protection would be necessary to minimize hydraulic fracturing and erosion of the flood plain, channel walls and the base. We recommend the protection layer to consist of at least 500 mm of crushed gabion stone (between 150 mm and 12 mm) and this should be separated from the subgrade by a suitable filter fabric, such as Terrafix 270R or approved equal. South of Borehole 5, Channel wall and base are recommended to be covered with at least 0.3 m of topsoil and to be vegetated to minimize surface erosion. Full-time qualified geotechnical engineering supervision should be provided during the excavation and construction of the channel to ensure that adequate protective measures are taken when necessary Culvert Foundations According to Grading Concept plan prepared by Urbantech, we understand that culvert structures are proposed at the site, one close to Highway 401 and another to provide conveyance below New Tremaine Road. However, the inverts were not available for our review. Based on the subsurface conditions encountered at the Boreholes 1 and 4 drilled closest to the proposed culverts, the undisturbed native deposits should provide adequate support for the proposed footings. We suggest that once the project details are finalized, we should be given the opportunity to provide additional recommendation. / Page 13

16 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, Slope Stability Analysis Considering the difference in elevations between the proposed grades for channel floor and the subdivision, being highest near the northwest part of the site, slope stability analysis was carried for the proposed steepest side slope of 3H:1V, as shown in Figure 3.1. The stability of the assumed section was analysed under the following conditions: -During Construction (undrained condition), -Normal Operation (drained condition) and -Under Regional Flood (undrained condition). The assumed cross-section was analyzed using the conservative soil parameters shown in Table 5. These were determined based on the subsurface condition encountered at borehole locations, the field and laboratory tests performed, our experience with similar site conditions as well as published geotechnical data. It should be noted that we have assumed the existing topsoil and any ploughed fill to be stripped and the grade to be raised to the proposed design elevations using clayey engineered fill. Table 5: Assumed Geotechnical Parameters Bulk Unit Weight (kn/m 3 ) Shear Strength Parameters Soil Type C Φ C u (kpa) (degree) (kpa) Engineered Clayey Fill Firm Silty Clay/Clayey Silt Till Compact Silty Sand Stiff Clayey Silt Φ u (degree) For slope stability analysis, computer program Slope/W 2007 and the Bishop s Simplified method for the calculation of the factor of safety (FOS) for slip surface were used. For a stable slope, we recommend a minimum FOS value of 1.5. The results of the analysis are shown in Enclosures C-1 to C-3. Accordingly, the calculated FOS values for assumed cross-section are above the recommended minimum value of 1.5 and are therefore considered to be stable. / Page 14

17 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, Proposed Stormwater Management Pond S43 (Boreholes 5, 6 and 13A) According to the information provided to us by Urbantech Consulting (Stormwater Management Facility, Figure No.4, dated March 2011), some of the design details for pond are summarized below: Pond Bottom Invert: Normal Water Level (NWL): High Water level (HWL): m m m Considering the above information and the existing grades at the site, the pond will generally be in cut but some engineered fill will be required towards the south end to raise the grades to the design level. The subsurface conditions encountered at Boreholes 5, 6 and 13A are summarized in the soil profile presented in Drawing No. 2 of Enclosure B. Considering this, the pond bottom and walls should generally occur within the stiff to hard but generally very stiff to hard silty clay/clayey silt till. However in the vicinity of Borehole 5, the bottom 1 m of the pond wall would occur within the moist to wet and compact silt Slope Stability Analysis Considering the above details, the stability of the pond walls was analyzed under the following conditions for the assumed cross-section through the east wall, as shown in Figure 3.2: -During Construction (undrained condition), -Normal Water Level (drained condition), -High Water Level (drained condition) and -Rapid Drawdown (undrained condition). The assumed cross-section was analyzed using the conservative soil parameters shown in Table 6. These were determined based on the subsurface condition encountered at the borehole locations, the field and laboratory tests performed, our experience with similar site conditions as well as published geotechnical data. / Page 15

18 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, 2011 Table 6: Assumed Geotechnical Parameters Shear Strength Parameters Soil Type Bulk Unit Weight (kn/m 3 ) C Φ C u Φ u (kpa) (degree) (kpa) (degree) Very Stiff to Hard Silty Clay/ Clayey Silt Till Compact Silt Stiff Silty Clay Till Engineered Fill For slope stability analysis, computer program Slope/W 2007 and the Bishop s Simplified method for the calculation of the factor of safety (FOS) for slip surface were used. For a stable slope, we recommend a minimum FOS value of 1.5. The results of the analysis are shown in Enclosures C-4 to C-7. Accordingly, the calculated FOS values for the assumed cross-section are above the recommended minimum value of 1.5 and are therefore considered to be stable Pond Excavation and Construction Dewatering Considering the existing and proposed grades as well as the subsurface conditions encountered at Boreholes 5, 6 and 13A as well as Test Pits 3 and 4, below the surfical topsoil and ploughed fill, the excavation for the pond would generally occur in a stiff to hard but generally very stiff to hard silty clay/clayey silt till. However, below an elevation of about 211 m in the vicinity of Borehole 5, moist to compact silt should also be anticipated. Furthermore, the boreholes have shown that the silt layer is under some artesian condition. All excavations should be carried out in accordance with the Ontario Health and Safety Regulations. The soils to be excavated can be classified as follows: Topsoil and Ploughed Fill Type 3 Stiff Silty Clay / Clayey Silt Till Type 3 Compact Silt (above groundwater) Type 3 Very stiff to hard Silty Clay/Clayey Silt Till Type 2 Accordingly, a side slope of 1H:1V is required for excavations in accordance with the Ontario Health and Safety Regulations. However, in Type 2 soils, the bottom 1.2 m of excavations within the very stiff to hard silty clay/clayey silt till, could be kept near vertical. Also near the surface and below the groundwater level within the silt deposit, flatter slopes may be required. / Page 16

19 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, 2011 Stockpiles of excavated materials should be kept at least 5.0 m from the edge of the excavation to avoid slope instability. Care should also be taken to avoid overloading of any underground services/structures by stockpiles. During excavation, minor seepage is expected from the stiff to hard silty clay/clayey silt till and this should be manageable by filtered sump pumps, if required. However, increased seepage should be expected when the excavation is extended below and into the compact silt. Considering the groundwater seepage at the two test pits excavated within the pond footprint, the seepage from the silt layer should also be manageable by increased sump pumps, if required. We recommend this to be confirmed by the Project Hydrogeologists Pond Construction Considering the highwater level and the presence of silt and sandy silt deposits at or close to the pond bottom on the north half of the pond, similar to the channel construction, some protection would be necessary to minimize hydraulic fracturing and erosion of the pond walls and base. We recommend the protection layer to consist of at least 500 mm of crushed gabion stone (between 150 mm and 12 mm) and it should be separated from the subgrade by a suitable filter fabric, such as Terrafix 270R or approved equal. Furthermore, depending on the amount of seepage from the silt layer, the use of a filtered subdrain may be required and this should be connected to a frost-free outlet. The surface of the silt and sandy silt should also be plugged with at least 0.5 m of compacted clay. This option and its appropriate design should be further assessed should be necessary. Full-time qualified geotechnical engineering supervision should be provided during the excavation and construction of the pond to ensure that adequate protective measures are taken when necessary Concrete Headwalls According to the information provided by Urbantech, concrete head walls will be placed on the south end of the pond at an invert elevation of m. Borehole 13A is located close to the proposed structures. Based on the subsurface conditions encountered at this borehole, the head walls will be founded on a very stiff to hard silty clay/clayey silt till and is considered to be capable of supporting the proposed structures for the SWM facility and they could be designed with a Factored Geotechnical Resistance at ULS (with a Geotechnical Resistance Factor of 0.5) and Recommended Geotechnical Reaction at SLS of 225 kpa and 150 kpa, respectively. The minimum footing sizes, footing thickness, excavations and other footing requirements should be designed in accordance to the latest edition of the Ontario Building Code. The footing subgrade should be inspected and evaluated by the Geotechnical Engineer prior to concreting to ensure that the footings are founded on competent subgrade capable of supporting the recommended design pressure. / Page 17

20 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, 2011 Design frost penetration depth for the general area is 1.2 m. Therefore, a permanent soil cover of 1.2 m or its thermal equivalent is required for frost protection of foundations. For footings designed and constructed in accordance with the above recommendation, the total settlement should be less than 25 mm. In conformance to the Criteria in Table A, Part 4, Division B of the National Building Code (NBC 2005), for footings designed as recommended above, the subject site is classified as Site Class D-Stiff Soils. The four values of the Spectral Response Acceleration S a (T) for the different periods and the peak ground acceleration (PGA) can be obtained from Table C-2 in Appendix C, Division B of the NBC (2005). The design values of F a and F v for the project site should be calculated in accordance to Table B and C. 4.3 Proposed Stormwater Management Pond S44 (Boreholes 8 and 9) According to the information provided to us by Urbantech Consulting (Stormwater Management Facility, Figure No.5, dated March 2011), some of the design details for the pond are summarized below: Pond Bottom Invert: Normal Water Level (NWL): Extended Detention Level (ExDL): High Water level (HWL): m m m m Considering the above information and the existing grades at the site, the pond will generally be in cut but some engineered fill will also be required towards the south end to raise the grades to the design level. The subsurface conditions encountered at Boreholes 8 and 9 are summarized in the soil profile presented in Drawing No. 3 of Enclosure B. Considering this, the pond bottom and walls should generally occur within the stiff to hard but generally very stiff to hard silty clay/clayey silt till Slope Stability Analysis Considering the above details, the stability of the pond walls was analyzed under the following conditions for an assumed cross-section through the north wall, as shown in Figure 3.3: -During Construction (undrained condition), -Normal Water Level (drained condition), -High Water Level (drained condition) and -Rapid Drawdown(undrained condition). The assumed cross-section was analyzed using the conservative soil parameters shown in Table 7. These were determined based on the subsurface condition encountered at the / Page 18

21 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, 2011 borehole locations, the field and laboratory tests performed, our experience with similar site conditions as well as published geotechnical data. Table 7: Assumed Geotechnical Parameters Shear Strength Parameters Soil Type Bulk Unit Weight (kn/m 3 ) C Φ C u Φ u (kpa) (degree) (kpa) (degree) Stiff Silty Clay Till Very Stiff to Hard Silty Clay/ Clayey Silt Till Engineered Fill For slope stability analysis, computer program Slope/W 2007 and the Bishop s Simplified method for the calculation of the factor of safety (FOS) for slip surface were used. For a stable slope, we recommend a minimum FOS value of 1.5. The results of the analysis are shown in Enclosures C-8 to C-11. Accordingly, the calculated FOS values for the assumed cross-section are above the recommended minimum value of 1.5 and are therefore considered to be stable Pond Excavation and Construction Dewatering Considering the existing and proposed grades as well as the subsurface conditions encountered at Boreholes 8 and 9 as well as Test Pits 7, below the surfical topsoil and ploughed fill, the excavation for the pond would generally occur in a stiff to hard but generally very stiff to hard silty clay/clayey silt till. However, in the vicinity of Borehole 9, below the surfical topsoil and ploughed fill, a relatively thin layer of moist and compact medium sand should also be anticipated. Furthermore, some artesian condition was also contacted in Borehole 9. All excavations should be carried out in accordance with the Ontario Health and Safety Regulations. The soils to be excavated can be classified as follows: Topsoil and Ploughed Fill Type 3 Stiff Silty Clay / Clayey Silt Till Type 3 Compact Medium Sand (above groundwater) Type 3 Very Stiff to Hard Silty Clay/Clayey Silt Till Type 2 Accordingly, a side slope of 1H:1V is required for excavations in accordance with the Ontario Health and Safety Regulations. However, in Type 2 soils, the bottom 1.2 m of excavations within the very stiff to hard silty clay/clayey silt till, could be kept near vertical. Also near the surface, some flatter slopes may be required. / Page 19

22 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, 2011 Stockpiles of excavated materials should be kept at least 5.0 m from the edge of the excavation to avoid slope instability. Care should also be taken to avoid overloading of any underground services/structures by stockpiles. During excavation, minor seepage is expected from the stiff to hard silty clay/clayey silt till and this should be manageable by filtered sump pumps, if required. This was also confirmed by the test pit that was excavated within the pond footprint. We recommend this to be confirmed by the Project Hydrogeologist Pond Construction Considering the high groundwater level that was measured in Borehole 9, we recommend that during excavation, the conditions to be further assessed by the project Geotechnical Engineer to explore the need against hydraulic fracturing and erosion Concrete Headwalls According to the information provided by Urbantech, concrete head walls are expected to be placed at about Elevation of 207 m. Considering the subsurface conditions encountered at Boreholes 8 and 9, the proposed structures will be founded on a very stiff silty clay till and is considered to be capable of supporting the proposed structures for the SWM facility and they could be designed with a Factored Geotechnical Resistance at ULS (with a Geotechnical Resistance Factor of 0.5) and Recommended Geotechnical Reaction at SLS of 225 kpa and 150 kpa, respectively. The minimum footing sizes, footing thickness, excavations and other footing requirements should be designed in accordance to the latest edition of the Ontario Building Code. The footing subgrade should be inspected and evaluated by the Geotechnical Engineer prior to concreting to ensure that the footings are founded on competent subgrade capable of supporting the recommended design pressure. Design frost penetration depth for the general area is 1.2 m. Therefore, a permanent soil cover of 1.2 m or its thermal equivalent is required for frost protection of foundations. For footings designed and constructed in accordance with the above recommendation, the total settlement should be less than 25 mm. In conformance to the Criteria in Table A, Part 4, Division B of the National Building Code (NBC 2005), for footings designed as recommended above, the subject site is classified as Site Class D-Stiff Soils. The four values of the Spectral Response Acceleration S a (T) for the different periods and the peak ground acceleration (PGA) can be obtained from Table C-2 in Appendix C, Division B of the NBC (2005). The design values of F a and F v for the project site should be calculated in accordance to Table B and C. / Page 20

23 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, Proposed Servicing for 3 rd Sideroad (Boreholes 10A to 13A) According to the figures provided by Urbantech (Figures 3.2 and 6 dated March 2011) storm and sanitary services are proposed from about Milton Heights Crescent to Peru Road. The sanitary line will be the deeper of the two services and its obvert will fall from west to east from Elevation at Manhole 22A to Elevation m at Manhole 27A. Boreholes 10A to 13A were drilled north of the existing 3 rd Sideroad and the subsurface conditions are summarized in Figure 4 of Enclosure B. It should be noted that no boreholes were drilled on the existing road due to existing overhead utilities and underground services Trenching Trench excavations should be carried out as per the Safety Regulations of the Province of Ontario. According to the subsurface conditions encountered at the borehole locations, below road fill, the trenching should predominantly occur within the stiff to hard but generally very stiff to hard silty clay / clayey silt till. However, near Borehole 10A, below Elevation 210.5, some firm to stiff clayey silt should also be expected. Furthermore, occasional compact silt and dense silty sand were also contacted at the boreholes which are believed to be under some artesian condition. All excavations should be carried out in accordance with the Ontario Health and Safety Regulations. The soils to be excavated can be classified as follows: Fill Type 3 Firm to Stiff Clayey Silt, Silty Clay / Clayey Silt Till Type 3 Compact Silt (above groundwater) Type 3 Very Stiff to Hard Silty Clay/Clayey Silt Till Type 2 Dense Silty Sand (above groundwater) Type 2 Within these soils, the side slopes of open excavations are expected to be temporarily stable at 1H:1V, although within the very stiff to hard clayey till deposits the bottom 1.2 m of the trench walls could be excavated close to vertical. It should be noted that when trenching below the groundwater, flatter slope would be required for the silt and silty sand layers. Based on the subsurface conditions encountered at the boreholes, which were drilled north of the existing road, groundwater seepage within the clayey deposits should be minor and manageable by gravity drainage and pumping from filtered sumps. However, increased seepage would occur from perched water or surface water flow or from silt and silty sand layers/interbeddings. Considering the groundwater conditions, we recommend that anti-seepage collars to be installed along the pipe alignment. We also recommend these to be further confirmed by the Project Hydrogeologists. In an attempt to reduce the width of the trenches as / Page 21

24 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, 2011 well as the groundwater seepage, consideration could be given to the use of a suitable temporary shoring system (such as trench boxes or slide rail systems). The appropriate method of shoring should be assessed by the contractor and/or their shoring specialists. We recommend the trenching to be backfilled as soon as possible. To prevent disturbance of the soil at the bedding level, the groundwater table must be lowered to at least 0.8 m below the invert of the trench. In no case should the pipes be placed on dilated or disturbed subsoil. Attention is called to the possible presence of cobbles and/or boulders that may be encountered during the excavation in the glacial till deposits. Normal excavation equipment will be suitable for making trenches within soils in which the proposed underground services will be installed. The terms describing the consistency (firm, stiff, very stiff, hard) or compactness (compact, dense) of soil strata give an indication of the effort needed for excavation Bedding The boreholes showed that the sewer pipes will be laid predominantly within the stiff to hard silty clay / clayey silt till deposit or stiff clayey silt or dense sandy silt which are suitable to support the pipes, provided that they are not disturbed during trenching. The recommended minimum thickness of granular bedding for normal Class B Type of bedding (i.e., compacted granular bedding material OPSD-802) below the invert is 150 mm. The thickness of the bedding may, however, have to be increased depending on the pipe diameter or if wet or weak subgrade conditions are encountered, especially around Boreholes 10A and 12A Backfill Based on the visual and tactile examination of the soil samples, the inorganic on-site excavated soils could be re-used as backfill in service trenches. The moisture contents at the time of construction should be at or near optimum. The clayey soils will likely be excavated in cohesive chunks and blocks and will be difficult to handle and compact. For use as backfill, the soils will have to be reduced to be smaller than 100 mm in size and placed in thin layers. The clayey soils will have to be compacted using heavy equipment suitable for these soils that may be difficult to operate in the narrow confines of the trenches. Unless the clayey materials are properly reduced in sizes, all organics and debris removed and compacted in sufficiently thin lifts, post-construction settlements could occur. The backfill should be placed in maximum 200 mm thick layers at or near (+ 2%) their optimum moisture content, and each layer should be compacted to at least 95 % Standard Proctor Maximum Dry Density. This value should be increased to at least 98 % within 0.6 m of the road subgrade surface. / Page 22

25 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, 2011 The excavated soils may require reconditioning (e.g., wetting or drying) prior to reuse. The onsite excavated soils should not be used in confined areas (e.g., around catch-basins and laterals under roadways) where heavy compaction equipment cannot be operated. The use of good backfill together with an appropriate frost taper would be preferable in confined areas. Unsuitable materials such as organic soils, boulders, cobbles, frozen soils, etc., should not be used for backfilling. We recommend that frost tapers be provided at backfilled trenches to ensure gradual transition from the frost-free materials to the frost susceptible natural soil, otherwise differential frost heaving may occur. Frost taper would not be necessary if the backfill material can be matched within the frost zone (i.e. within about 1.2 m depth below the pavement surface) with subgradetype material Pavement Thickness Pavement Structure The competent native silty clay/clayey silt till or properly placed engineered fill may be used as subgrade. Using good engineering and construction practice, the following minimum pavement structure may be used as per the Town of Milton standards: PAVEMENT STRUCTURE COMPACTION LOCAL- RESIDENTIAL (mm) HL-3 Asphaltic Concrete HL-8 Asphaltic Concrete 97 % Marshall Density Granular A Base 100 % Granular B Sub-base 100 % 300 NOTE: HL-3 and HL-8 asphaltic concrete to conform to Ministry of Transportation s Number SP110F12. To ensure the longevity of the pavement, the roadbed should be well drained at all times. We recommend that full-length perforated sub-drain pipes of 150 mm diameter be installed along both sides of the road, below the roadbed level, to ensure effective drainage. The sub-drain pipes should be surrounded by 20 mm size clear stone drainage zone of minimum 150 mm thickness, which should have non-woven geotextile (non-woven geotextile, with FOS of µm, Class II) wraparound to minimize infiltration of fines in pipes which would reduce their effectiveness. / Page 23

26 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, 2011 The granular materials should be compacted as per American Society for Testing and Material s Number D698. The placing, spreading and rolling of the asphalt should be in accordance with Ontario Provincial Standard Specifications Form 310, or equivalent. Construction traffic over exposed subgrade materials should be minimized, and temporary construction hauling routes should be established. If these routes coincide with future paved areas, adequately reinforced haul roads (increased thickness of granular base, use of geofabrics, etc.) should be constructed to reduce disturbance to the subgrade soils. These provisions are particularly important if the construction is scheduled during wet and cold seasons Construction Comments In order to provide a durable pavement structure, the following pavement construction method is recommended. The subgrade should be adequately prepared to receive the sub-base course. Any disturbed and wet subgrade materials should be removed and the top of the subgrade should then be inspected and approved, by proof-rolling, by qualified geotechnical personnel. Cavities created by the removal of unsuitable materials should be backfilled with approved, inorganic fill materials similar to the existing subgrade material. All new fill should be placed in maximum 200 mm loose lifts within ± 2 % of its optimum moisture content, and each lift compacted with suitable equipment to minimum 95 % Standard Proctor Maximum Dry Density, before placing the next lift. The uppermost zones of the roadfill, within 600 mm of the roadbed, should be compacted to minimum 98 % Standard Proctor Maximum Dry Density. If construction of the roadfill is carried out in wet weather, the thickness of the sub-base course should be increased. Special attention should be paid to proper grading of the subgrade surface. Depressions and undulations should be eliminated and, to permit quick drainage, the subgrade surface should be sloped towards ditches, sub-drains and/or catch-basins. It is recommended that a programme of geotechnical/material inspection and testing be carried out during the construction phase of the project to confirm that the conditions exposed in the excavations are consistent with those encountered in the boreholes and the design assumptions, and to confirm that the various project specifications and materials requirements are being met. 4.5 Engineered Fill For the raising the existing grade to the proposed elevation, engineered fill would be required. / Page 24

27 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, 2011 The following placement procedure is recommended. (i) (ii) (iii) (v) The area to receive the engineered fill should be stripped of any topsoil, fill and other compressible, weak and deleterious materials. After stripping, the entire area should be inspected and approved by the geotechnical engineer. Spongy, wet or soft/loose spots should be sub-excavated to stable subgrade and replaced with compactable approved soil, compatible with subgrade conditions, as directed by the geotechnical engineer. We recommend the engineered fill to consist of low-permeable clayey soils. The fill material should be placed in thin layers not exceeding approximately 200 mm when loose. Oversize particles (cobbles and boulders) larger than 120 mm should be discarded, and each fill layer should be uniformly compacted with heavy compactors, suitable for the type of fill used, to at least 98 % of its Standard Proctor Maximum Dry Density. Full-time geotechnical inspection and quality control (by means of frequent field density and laboratory testing) are necessary for the construction of a certifiable engineered fill. Compaction procedures and efficiency should be controlled by a qualified geotechnical technician. The engineered fill should not be frozen and should be placed at a moisture content within 2 % of the optimum value for compaction. The engineered fill should not be performed during winter months when freezing ambient temperatures occur persistently or intermittently. 5.0 CLOSURE We recommend that once the project details are finalized, our recommendations should be reviewed for their specific applicability. The attached Report Limitations are an integral part of this report. Sincerely, Shad & Associates Inc. Stephen Chong, P. Eng. Senior Engineer Houshang Shad, Ph.D., P. Eng. Principal / Page 25

28 STATEMENT OF LIMITATION The conclusions and recommendations given in this report are based on information obtained at the testhole locations. Subsurface and groundwater conditions between and beyond the testholes may differ from those encountered at the testhole locations, and conditions may become apparent during construction which could not be detected or foreseen at the time of the site investigation. The information contained herein in no way reflects on the environmental aspects of the project, unless stated otherwise. The benchmark and elevations used in this report are primarily to establish relative elevation differences between the testhole locations and should not be used for other purposes, such as planning, grading, excavating, etc. The design recommendations given in this report are project as well as site specific and then only if constructed substantially in accordance with the details stated in this report. We recommend, therefore, that we be retained during the final design stage to review the design drawings and to verify that they are consistent with our recommendations or the assumptions made in our analysis. The comments given in this report on potential construction problems and possible methods are intended only for the guidance of the designer. The number of the testholes may not be sufficient to determine all the factors that may affect construction methods and costs. The contractors bidding on this project or undertaking construction should, therefore, make their own interpretation of the factual information presented and draw their own conclusions as to how the subsurface conditions may affect their work. We recommend that we be retained during construction to confirm that the subsurface conditions throughout the site do not deviate materially from those encountered in the testholes. Any use which a third party makes of this report, or any reliance on or decisions to be made based on it, is the responsibility of such third party. We accept no responsibility for damages, if any, suffered by any third party as a result of decisions made or actions based on this report.

29 Royal Park Homes & Century Grove Homes c/o Urbantech Consulting Geotechnical Investigation Report Proposed Channel, SWM Ponds & 3 rd SDRD Servicing Tremaine Rd and 3 rd SDRD, Milton, Ontario Reference Number: T11284 July 15, 2011 FIGURES

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