Geotechnical Investigation Report Recreation Centre Building Braeside, Ontario

Transcription

1 Geotechnical Investigation Report Recreation Centre Building Braeside, Ontario Cambium Reference No.: Prepared for: Greenview Environmental Management Cambium Inc. P.O. Box Hunter Street East, Peterborough Ontario, K9H 1G5 Telephone: (866) Facsimile: (705) cambium-inc.com

2 TABLE OF CONTENTS 1.0 INTRODUCTION METHODOLOGY DESKTOP REVIEW PHYSICAL LABORATORY TESTING SUBSURFACE CONDITIONS TOPSOIL SILTY GRAVEL OVERBURDEN BEDROCK GROUNDWATER GEOTECHNICAL CONSIDERATIONS SITE PREPARATION FROST PENETRATION EXCAVATIONS DEWATERING BACKFILL AND COMPACTION SEISMIC SITE CLASSIFICATION FOUNDATION DESIGN SUBDRAINAGE BURIED UTILITIES PAVEMENT DESIGN DESIGN REVIEW AND INSPECTIONS CLOSING... 9 LIST OF APPENDED FIGURES Figure 1 Test Pit Locations LIST OF INSERTED TABLES Table 1 Particle Size Distribution Silty Gravel... 3 Table 2 Recommended Minimum Pavement Structure... 7 LIST OF INSERTED TABLES Appendix A Test Pit Logs Appendix B Physical Laboratory Testing Cambium Inc. Page i

3 1.0 INTRODUCTION Cambium Inc. (Cambium) was retained by Greenview Environmental Management to complete a geotechnical report in support of the design and construction of the proposed new (replacement) recreation centre at 138 Sarah Street East in Braeside, Ontario (Site). The property consists of a cleared central lot with sports facilities including a baseball diamond and hockey rink along with a municipal building. The surrounding land is wooded and includes residential homes. The geotechnical report is based on subsurface information from a test pit investigation of the site area completed by Cambium in October, 2015 and provides geotechnical design parameters as input into the design and construction of the proposed structure, site servicing, and road construction. A Site Plan, including test pit locations, is included as Figure 1 of this report. This report presents the methodology and findings of the geotechnical investigation at the Site and addresses requirements and constraints for the design and construction of the buildings, pavement structure, and underground servicing. Cambium Inc. Page 1

4 2.0 METHODOLOGY 2.1 DESKTOP REVIEW A test pit investigation was conducted in the site area on October 22, 2015, to assess subsurface conditions for a proposed works garage and other potential structures. The original purpose of the geotechnical investigation was for the design and construction of the proposed new municipal garage and sand storage building adjacent to the recreation centre. Due to the close proximity of the original test pit investigation, the previous findings are applicable to the Recreation Centre project. The Site of the new recreation centre is bound by a total of three (3) test pits, designated as TP5, TP12 and TP13. These test pits were advanced into the subsurface on the property using a backhoe and operator provided by Cambium. Test pits were advanced to bedrock refusal depths ranging from 0.8 m to 1.10 m below ground surface (mbgs). The onsite Cambium technician supervised all excavations and completed Dynamic Probe Penetration testing (DPT) at all test pit locations, consisting of recording the number of blows required to drive a 19 mm diameter steel rod into the soil with an 8 kg hammer falling 750 mm. The DPT values are used to assess consistency of cohesive soils and relative density of non-cohesive materials, similar to SPT N values. DPT testing extended to terminal depths of all test pits or on practical refusal. The Cambium technician logged and sampled the test pits at regular intervals using both visual and tactile methods. Samples were placed in moisture preserving sample bags for transport, future reference, possible laboratory testing, and storage for up to three (3) months after completion of the project. After completion of the test pit it was checked for groundwater and general stability prior to backfilling. 2.2 PHYSICAL LABORATORY TESTING A sieve analysis (LS-702) was completed for one of the soil samples from the three test pits previously mentioned, to confirm textural classification and to assess geotechnical parameters. Natural moisture content testing (LS-701) was completed on all retrieved soil samples, Results are presented in Appendix B and are discussed in Section 3.0 of this report. Cambium Inc. Page 2

5 3.0 SUBSURFACE CONDITIONS The subsurface conditions at the site predominantly consist of silty sand topsoil overlying silty gravel material with broken limestone and shale boulders to bedrock refusal on competent limestone. Underlying the topsoil and above the silty gravel in TP12 and TP13 a layer of sandy silt and sand respectively was encountered. The test pit locations are shown on Figure 1 and the individual soil units are described in detail below. 3.1 TOPSOIL In all three test pits, the surficial soils had consistent silty sand to sandy silt texture and were considered to be organic rich with roots often extending to near bedrock depths. The brown to black topsoil ranged in thickness from 150 mm to 400 mm, with an average thickness of approximately 275 mm. The topsoil was generally moist at the time of the investigation. Assessments of organic matter content or other topsoil quality tests were beyond the scope of this study. 3.2 SILTY GRAVEL OVERBURDEN Overburden soils throughout the Site generally consisted of native silty gravel soils, with some sand and often some broken limestone cobbles to boulders. These soils were encountered to bedrock terminal depths ranging from 0.80 mbgs to 1.10 mbgs. The thickness of this overburden soil across the three test pits ranged from 0.4 m to 0.6 m. The silty gravel overburden material varied in colour from light brown to grey and was dry to moist at the time of the investigation, with natural moisture content varying from 10% to 23%. Based on DPT values the silty gravel material can be said to have a relative density of compact to very dense. Laboratory particle size distribution analysis was completed for (1) sample of the overburden soil, in order to characterize the onsite soils. The soil samples and analysis results are identified in Table 1 based on the Unified Soil Classification System (USCS) and the analysis results are provided in Appendix B. Table 1 Particle Size Distribution Silty Gravel Borehole Depth (mbgs) Description % Gravel % Sand % Silt and Clay TP Silty Gravel BEDROCK Bedrock was encountered in every test pit excavated on site at depths ranging from 0.80 mbgs to 1.10 mbgs. The surface of the bedrock was consistently a competent limestone with regions of increased weathering that allowed boulders to break off. Cambium Inc. Page 3

6 3.4 GROUNDWATER Groundwater was not encountered at the depths excavated for this investigation, which ranged from 0.80 mbgs to 1.10 mbgs. It should be noted that groundwater levels at the site may fluctuate seasonally and in response to climatic events. Cambium Inc. Page 4

7 4.0 GEOTECHNICAL CONSIDERATIONS The following recommendations are based on test pit information and are intended to assist designers. Recommendations should not be construed as providing instructions to contractors, who should form their own opinions about site conditions. It is possible that subsurface conditions beyond the test pit locations may vary from those observed. If significant variations are found before or during construction, Cambium should be contacted so that we can reassess our findings, if necessary. 4.1 SITE PREPARATION Any existing topsoil and any soils identified with organic content at the Site should be excavated and removed from beneath any areas of the Site to be developed including for roadway construction and parking lots. We understand that the proposed structures will not include basements so the footings will be placed at bedrock depth ranging from 0.80 mbgs to 1.10 mbgs. It is recommended that any weathered bedrock be removed from below all footing locations. 4.2 FROST PENETRATION Based on climate data and design charts, the maximum frost penetration at the Site is estimated at 1.8 m. Although this exceeds the likely footing depth frost penetration for the footings will not be an issue as they will be constructed atop unweathered competent bedrock. Inspections of the bedrock by qualified geotechnical technicians is recommended to ensure that the bedrock below the footings has no frost susceptible silty or clayey seams.it is assumed that the pavement structure thickness will be less than 1.8 m, so grading and drainage are important for good pavement performance and life expectancy. 4.3 EXCAVATIONS Temporary excavations must be carried out in accordance with the latest edition of the Occupational Health and Safety Act (OHSA). The generally compact to very dense silty gravel to silty gravel soils may be classified as Type 2 soils in accordance with OHSA, with side slopes no steeper than 1H:1V. Excavation side slopes should be protected from exposure to precipitation and associated ground surface runoff and should be inspected regularly for signs of instability. If localized instability is noted during excavation or if wet conditions are encountered, the side slopes should be flattened as required to maintain safe working conditions or the excavation sidewalls must be fully supported (shored). Cambium Inc. Page 5

8 4.4 DEWATERING Groundwater was not encountered during the field investigation but it is noted that the elevation of the groundwater table will vary due to seasonal conditions and in response to heavy precipitation events. If groundwater is encountered, it should be controllable with filtered sumps and pumps and a Permit to Take Water (PTTW) from the Ministry of the Environment (MOE) will not be required. 4.5 BACKFILL AND COMPACTION Excavated native silty gravel from the site may be appropriate for use as fill below grading and parking areas, provided that the actual or adjusted moisture content at the time of construction is within a range that permits compaction to required densities. Some moisture content adjustments may be required depending upon seasonal conditions. Geotechnical inspections and testing of engineered fill are required to confirm acceptable quality. Engineered fill for foundations should be placed in maximum 200 mm thick lifts and should be compacted to a minimum of 100% of standard Proctor maximum dry density (SPMDD). Foundation wall backfill should be compacted to 98% of SPMDD. Foundation wall backfill should consist of free-draining imported granular material. With the exception of some of the silty gravel, most of the native site soils are too fine-grained to provide proper drainage. Placement of engineered fill should be verified by onsite compaction testing during construction. 4.6 SEISMIC SITE CLASSIFICATION The Ontario Building Code (OBC) specifies that the structures should be designed to withstand forces due to earthquakes. For the purpose of earthquake design, geotechnical information shall be used to determine the Site Class. The seismic Site Class is determined based upon the average properties in the top 30 m below grade. All of the test pits advanced on site encountered limestone bedrock at depths ranging from 0.80 mbgs to 1.10 mbgs. Based on these results and in accordance with Table A of the OBC (2006) Site Class C (very dense soil and soft rock) is recommended to be applied for structure design at this Site. 4.7 FOUNDATION DESIGN Assuming that the Site is prepared as outlined above, the bedrock encountered from 0.80 mbgs to 1.10 mbgs is competent to support the structures on conventional strip and spread footings. For design purposes, the factored geotechnical resistance for the limestone bedrock at footing depth can be taken as 700 kpa at Ultimate Limit State (ULS). ULS will govern as settlement of footings set on clean limestone bedrock will be negligible. These values are based on criteria in the Canadian Foundation Engineering Manual (4 th edition). Cambium Inc. Page 6

9 4.8 SUBDRAINAGE As the proposed building expansion does not include a basement, groundwater seepage is not anticipated at a footing depth of 1.1 mbgs. Foundation subdrains are not required around the perimeter of the foundation. 4.9 BURIED UTILITIES Trench excavations should generally consider Type 2 soil conditions which can be excavated with vertical side slopes no steeper than 1H:1V. Significant groundwater seepage into shallow trench excavations is not anticipated, but if encountered, should be controllable using filtered sumps and pumps within the excavations. Where deeper services are anticipated, advance dewatering may be required and, once dewatered, the soils may be classified as Type 2 soils as above. Bedding and cover material for any services should consist of OPSS Granular A or B Type II, placed in accordance with pertinent Ontario Provincial Standard Drawings (OPSD ). The bedding and cover material shall be placed in maximum 200 mm thick lifts and should be compacted to at least 98 percent of SPMDD. The cover material shall be a minimum of 300 mm over the top of the pipe and compacted to 98 percent SPMDD, taking care not to damage the utility pipes during compaction PAVEMENT DESIGN The performance of the pavement is dependent upon proper subgrade preparation. All topsoil and organic materials should be removed down to native material and backfilled with approved engineered fill or native material, compacted to 98 percent SPMDD. The subgrade should be proof rolled and inspected by a Geotechnical Engineer. Any areas where rutting or appreciable deflection is noted should be subexcavated and replaced with suitable fill. The fill should be compacted to at least 98 percent SPMDD. The recommended minimum pavement structure design has been developed for two (2) traffic loading scenarios; light duty and heavy duty. The heavy duty design is appropriate for areas where some truck/bus traffic is anticipated while the light duty design is appropriate for areas where no truck/bus traffic is anticipated. The recommended minimum pavement structure is provided in Table 2. Table 2 Recommended Minimum Pavement Structure Pavement Layer Light Duty Heavy Duty Surface Course Asphalt 50 mm HL3 or HL4 40 mm HL3 or HL4 Binder Course Asphalt 50 mm HL8 Granular Base 150 mm OPSS 1010 Granular A 150 mm OPSS 1010 Granular A Granular Subbase 250 mm OPSS 1010 Granular B 300 mm OPSS 1010 Granular B Material and thickness substitutions must be approved by the Design Engineer. Cambium Inc. Page 7

10 The thickness of the subbase layer could be increased at the discretion of the Engineer, to accommodate site conditions at the time of construction, including soft or weak subgrade soil replacement. Compaction of the subgrade should be verified by the Engineer prior to placing the granular fill. Granular layers should be placed in 150 mm maximum loose lifts and compacted to at least 98 percent of SPMDD (ASTM D698) standard. The granular materials specified should conform to OPSS standards, as confirmed by appropriate materials testing. The final asphalt surface should be sloped at a minimum of 2 percent to shed runoff. Abutting pavements should be sawcut to provide clean vertical joints with new pavement areas DESIGN REVIEW AND INSPECTIONS Cambium should be retained to complete testing and inspections during construction operations to examine and approve subgrade conditions, placement and compaction of fill materials, granular base courses, and asphaltic concrete. We should be contacted to review and approve design drawings, prior to tendering or commencing construction, to ensure that all pertinent geotechnical-related factors have been addressed. It is important that onsite geotechnical supervision be provided at this site for excavation and backfill procedures, deleterious soil removal, subgrade inspections and compaction testing. Cambium Inc. Page 8

11 5.0 CLOSING We trust that the information contained in this report meets your current requirements. If you have questions or comments regarding this document, please do not hesitate to contact the undersigned at (705) ext Respectfully submitted, CAMBIUM INC. Stuart Baird, P.Eng. Senior Project Manager SEB P:\6000 to 6099\ Greenview Environmental Management Limited - Braeside RA Centre\Deliverables\ Braeside Recreation Centre Geotech. Report.docx Cambium Inc. Page 9

12 March 9, 2017 Appended Figures Cambium Inc.

13 PHILLIPS STREET WILLIAM MEEK DRIVE º GEOTECHNICAL INVESTIGATION GREENVIEW ENVIRONMENTAL MANAGEMENT BRAESIDE RECREATIONAL ACTIVITIES CENTRE 138 Sarah Street East Braeside, Ontario SARAH STREET EAST TP5 ED TP13 ED RIVER ROAD CENTRE STREET ED LEGEND Test Pit Locations Subject Property (approx.) TP12 ED O:\GIS\project_MXDs\ \ Greenview Environmental Management Limited - Braeside RA Centre\ FIG 1 Test Pit Location Plan.mxd BURNS DRIVE m Notes: - Subject Property Boundary obtained from the County of Renfrew online mapping, October imagery accessed March, 2017 from ArcGIS Online. Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community - Base mapping features are Queen's Printer of Ontario, 2010 (this does not constitute an endorsement by the Ministry of Natural Resources or the Ontario Government). - Distances on this plan are in metres and can be converted to feet by dividing by Cambium Inc. makes every effort to ensure this map is free from errors but cannot be held responsible for any damages due to error or omissions. This map should not be used for navigation or legal purposes. It is intended for general reference use only. P.O. Box 325, 52 Hunter Street East Peterborough, Ontario, K9H 1G5 Tel: (705) Fax: (705) TEST PIT LOCATION PLAN Project No.: Date: March Rev.: Scale: Projection: 1:2,500 NAD 1983 UTM Zone 17N Created by: Checked by: Figure: GJM SEB 1

14 March 9, 2017 Appendix A Test Pit Logs Cambium Inc.

15 TEST PIT LOGS Greenview Environmental Management New Recreation Centre - Braeside, Ontario Cambium Reference No Test Pit ID Depth (mbgs 1 ) Material Description Depth (mbgs) DPT 2 (Blows/150mm) TP TOPSOIL: Brown to black silty sand topsoil, organic rich, heavily rooted, moist, roots extend to 0.50 m SILTY GRAVEL: Light brown to silty gravel, some sand, broken limestone and shale (weathered bedrock), dry to moist >20 Test pit dry and terminated at 0.80 m depth on competent limestone bedrock TP TOPSOIL: Brown topoil mixed with granular fill material, sandy silt and gravel, moist SANDY SILT: Brown sandy silt, trace clay, trace organics, moist SILTY GRAVEL: Brown to grey silty gravel, some sand, some cobbles, broken limestone, dry to moist Test pit dry and terminated at 1.10 m depth on competent limestone bedrock TP TOPSOIL: Brown sandy silt topsoil, organic rich, moist SAND: Brown sand, some silt, trace organics, moist SILTY GRAVEL: Brown silty gravel, broken limestone, sandy seams present, dry to moist, roots to 0.60 m >20 Test pit dry and terminated at 1.05 m depth on competent limestone bedrock Notes: 1. mbgs = metres below ground surface 2. Dynamic probe penetration test, consisting of driving a 19 mm diameter steel rod into the soil with an 8 kg hammer falling 750 mm.

16 March 9, 2017 Appendix B Physical Laboratory Testing Cambium Inc.

17 PERCENT PASSING PERCENT RETAINED Grain Size Distribution Chart Project Number: Client: Greenview Environmental Management Project Name: New Municipal Garage and Sand Storage Building Sample Date: October 22, 2015 Sampled By: Kyle Thompson - Cambium Inc. Hole No.: TP12 S1 Depth: 0 m to 0.4 m Lab Sample No: S UNIFIED SOIL CLASSIFICATION SYSTEM CLAY & SILT (<0.075 mm) FINE SAND (<4.75 mm to mm) MEDIUM GRAVEL (>4.75 mm) COARSE FINE COARSE DIAMETER (mm) MIT SOIL CLASSIFICATION SYSTEM CLAY SILT FINE MEDIUM COARSE FINE MEDIUM COARSE SAND GRAVEL BOULDERS Borehole No. Sample No. Depth Gravel Sand Silt Clay Moisture TP12 S1 0 m to 0.4 m Description Classification D 60 D 30 D 10 C u C c Silty Gravel GM Issued By: (Senior Project Manager) Date Issued: November 5, 2015 Cambium Inc. (Laboratory) cambium-inc.com 701 The Queensway Units 5-6 Peterborough ON K9J 7J6 Form 11.V1-Grad.Analysis