patersongroup Consulting Engineers April 3, 2012 File: PG2637-REP.01

Transcription

1 April 3, 2012 Kanata Entertainment Holdings Inc. 10 Dundas Street East, Suite 1002 Toronto, Ontario M5B 2G9 Consulting Engineers 154 Colonnade Road South Ottawa, Ontario Canada, K2E 7J5 Tel: (613) Fax: (613) Geotechnical Engineering Environmental Engineering Hydrogeology Geological Engineering Materials Testing Building Science Attention: Mr. John MacKay Subject: Geotechnical Investigation Summary Proposed Les Trois Brasseurs Block S, Kanata Centrum, Phase 3 Ottawa (Kanata), Ontario Dear Mr. MacKay: 1.0 Introduction Paterson Group Inc. (Paterson) was commissioned by PenEquity Realty Corporation (PenEquity), acting on behalf of Kanata Entertainment Holdings Inc., under P.O. No. 0971, to prepare a geotechnical investigation summary for the proposed Les Trois Brasseurs restaurant, comprising Block S in Kanata Centrum, in Ottawa (Kanata). The objectives of the investigation were to review the results of previous investigative work at the subject site, including Block S and, based on the results of the previous test holes, to provide geotechnical recommendations for the design of the proposed commercial building, in conformance with the current Ontario Building Code (OBC 2006), including construction considerations which may affect its design. The following report has been prepared specifically and solely for the aforementioned project which is described herein. It contains a summary of our findings and includes geotechnical recommendations pertaining to the design and construction of the proposed building as they are understood at the time of writing this report. 2.0 Previous Investigation Work Results from previous investigations, consisting of test pits and boreholes have been reviewed in the preparation of this geotechnical investigation report. All test holes within the area of the subject proposed development are shown on the attached Test Hole Location Plan, Drawing No. PG

2 Page 2 Test pits were advanced using a backhoe or a track-mounted hydraulic shovel to practical refusal on the bedrock. The soil profiles were logged by direct examination of the walls of the test pit excavations. Representative soil samples were recovered of typical materials. The samples were classified on site, placed in sealed plastic bags and transported to our laboratory. The depths at which the samples were recovered in the test pits are shown as G samples in the attached Soil Profile and Test Data sheets. The boreholes were put down using specialist geotechnical drilling equipment, consisting of a truck or track mounted CME power auger. The boreholes were taken to the depth of practical auger refusal. Samples were recovered from the boreholes using a split spoon sampler in conjunction with the standard penetration test. The ground level at the time of the respective investigation was determined for each test hole, with respect to geodetic datum. The subsurface conditions observed in the test holes were recorded in detail in the field. The soil profiles of the closest test holes are logged on the attached Soil Profile and Test Data sheets. The test hole locations are shown on the attached Test Hole Location Plan, Drawing No. PG (test hole logs for ghosted test holes are not included). 3.0 Site Conditions 3.1 Ground Surface Conditions The ground surface over the proposed building area is relatively flat and consists of a grassed area surrounded by sidewalks. The intention is to construct the building with minimal disturbance to the surrounding sidewalk pavement structures. The existing ground surface in the Blocks S area is at about the same grade as the adjacent pavements, and very close to the proposed floor slab finished grade. 3.2 Subsurface Profile Reference should be made to the Soil Profile and Test Data sheets in Appendix 1 for the details of the subsurface profile at each test hole location. The reader is reminded that the subsurface conditions have been determined at the test locations only and interpretation of conditions between test hole locations should be done with caution. It should also be assumed that the surface conditions at the test hole locations may have changed since the test hole was completed, due to subsequent development, as applicable.

3 Page 3 Overburden Soils and Fill The site is underlain by existing fill materials consisting primarily of silty fine to medium sand and blast rock. The blast rock consists primarily of sandstone rock from the adjacent AMC Theatre project and/or services installation. Some remnant in situ soils are expected to be encountered below the fill. The in situ soils consist of silty sand to sandy silt and/or silty sand gravel glacial till. These granular soils are estimated to have a state of compaction within the loose to compact ranges. The fill and/or in situ soils are underlain by bedrock. Groundwater All test holes at the subject site were dry and groundwater was not encountered. However, groundwater can be expected to be perched over the bedrock in deeper bedrock locations, especially after significant precipitation effects. Also, groundwater levels can be expected to fluctuate seasonally and to be higher after lengthy periods of precipitation and/or during spring thaw. Bedrock The bedrock underlying the site consists of sandstone of the Nepean Formation. This formation, which has been encountered over much of the adjacent development area, is characterized by horizontal bedding planes, at variable intervals of depth. The inferred or observed surface levels of the bedrock at each borehole and test pit location are shown in parentheses on the Test Hole Location Plan. It has been our experience with exposures of the Nepean Formation that changes in the bedrock surface elevation occur in a stepping, rather than sloping manner. A 0.8 m high step was observed in TP 35 to the northeast of Block S. The structural quality of the sandstone bedrock is dependent on the frequency of defects in the bedrock mass, such as open bedding planes, joints, mud seams, etc. The bedrock structural quality is expected to be generally fair, although it will vary from poor to excellent. Excavation into the bedrock beyond the shallow weathered surface will require some form of fragmentation, such as hoe-ramming or blasting. Based on the test hole information, the bedrock surface is very shallow within essentially the east part of the foot print of Block S. Within this area, the inferred and/or observed bedrock surface is higher than el. 97.3± m. Test holes to the northwest and southwest have lower bedrock surface levels, so the bedrock surface appears to trend downward to the west.

4 Page Conclusions and Recommendations 4.1 Founding Conditions It is recommended that the proposed building be founded exclusively on bedrock or on engineered granular fill over bedrock. The proposed Block S building will be founded on conventional spread footing foundations, as has been done for all the other structures in the Kanata Centrum development. The building is expected to have a finished floor level of approximately el m. For purposes of discussion, typically exterior footings are founded at about 1.6 metres below the finished floor level (depending on exterior grade) to provide the required soil cover for frost protection and interior footings are founded at a minimum of about 1.0 m below the floor level. In the case of exterior footings that encounter the bedrock before the required soil cover is achieved, exterior foundation insulation can be used where a minimum of 0.6 m of soil cover is provided (i.e. exterior footings founded at about 0.7 m below the finished floor level. Recommended Bearing Media It should be noted at this point that the use of a uniform bearing medium, most probably the bedrock, would provide the best foundation performance, as differential settlement would not be of concern. However, if the bedrock surface level drops significantly, the use of a combined bearing medium of bedrock and engineered fill is also acceptable, where necessary. Provided the transition between the two bearing media is reasonably gradual and does not occur in steps greater than 0.6 m in height, no transition point treatment should be required at locations where the bearing medium changes from one type to the other. Otherwise, consideration will be required to the use of transition point treatment, and some potential for differential settlement between the bearing media types should be expected. Expected Footing Levels The proposed Trois Brasseurs (Block S) building will have a finished ground floor level of approximately el m. As such, the approximate routine footing levels for Block S (assuming no depressed loading dock ramp) will be as follows: Exterior Footing Level (for full soil cover): Interior Footing Level: Maximum Footing Level (for minimum soil cover): El m El m El m

5 Page 5 The Block S pad is inferred to have relatively shallow bedrock levels. As such, it is recommended that the interior and exterior footings for this structure be founded entirely on the bedrock bearing medium. This may require interior footings to be founded deeper in the profile than would be the normal case, and the difference can be made up either by thickening the footing, or constructing a short pier. Where exterior footings would require bedrock excavation to provide the full soil cover for frost protection, these footings can be founded on the bedrock at shallower depth and insulated with extruded polystyrene foam (XPS) insulation to provide the required equivalent soil cover for frost protection. The minimum footing level provided above provides the minimum soil cover of about 0.6 m that is recommended for an insulated footing design. These values should be checked against the actual exterior finished grades, when these have been finalized, and be adjusted accordingly, if necessary. 4.2 Foundation Design Bedrock Bearing Medium A clean bedrock surface can be taken to have a bearing resistance at serviceability limit states (SLS) of 500 kpa, to be confirmed by geotechnical field review at the time of exposure of the foundations. The bearing resistance at SLS value is equivalent to the allowable bearing pressure used with working stress design methods. A clean bedrock surface can be taken to have a factored bearing resistance at ultimate limit states (ULS) of 750 kpa. This value incorporates a geotechnical resistance factor of 0.5. A clean bedrock surface is one from which all soil, loose rock and other deleterious materials have been removed prior to the placement of concrete for footings. Engineered Granular Fill Bearing Medium An engineered granular fill bearing medium, consisting of a minimum of 0.3 metres of OPSS Granular B Type II (50 mm minus) crushed stone placed and compacted to a minimum of 95% of its standard Proctor maximum dry density (SPMDD), over an undisturbed in situ soil or clean bedrock subgrade, can be taken to have a bearing resistance at SLS 150 kpa, and a factored bearing resistance at ULS of 225 kpa. Engineered granular fill is required to extend laterally, a dimension at least equivalent to 1.5 times the engineered fill layer thickness, beyond all footing edges.

6 Page 6 Settlement Bedrock-supported footings can be taken to have negligible potential settlement, as compared to engineered fill-supported footings. Potential differential settlement between the soil and/or fill-supported footings and bedrock-supported footings will approach the potential total settlement of the footings of about 25 mm. Potential differential settlement between footings, both founded on the same engineered fill bearing medium will be of the order of 20 mm. Transition point treatment, where footings cross from bedrock to engineered granular fill, would be evaluated in the field with respect to the sharpness of the transition. If required, it is likely that the treatment would involve either excavating bedrock along the bedrock surface as it drops off and filling the zone with more engineered fill to make a shallower transition, or installing a buffer of compressible insulation (i.e. 50 mm Styrofoam SM) over the last portion of the bedrock bearing surface to avoid formation of a pressure point. These treatments should be considered to be field review recommendations that would only be recommended under special conditions, and are not part of the basic design. Required Lateral Support to Bearing Media Sufficient lateral support is provided to an engineered granular fill bearing medium when a plane extending down and out from the bottom edge of the footing at 1.5H:1V passes only through engineered fill, or mass concrete of the same or higher capacity as the bearing medium. Footings on bedrock bearing media should not straddle high steps or be located directly at the edge of a step in the bedrock surface, depending on the infill material on the side of the step. These conditions, if encountered, can be evaluated during the field review by the geotechnical consultant and recommendations for corrective action, such as removing bedrock on the high side of the step, can be provided if and where required. 4.3 Seismic Design of Foundations The site class for seismic site response can be taken as Class C for the foundations considered at this site. Reference should be made to the latest revision of the 2006 Ontario Building Code for a full discussion of the earthquake design requirements. A higher site class, such as Class B or A may be applicable for the proposed building. However, the higher site class would have to be confirmed with site specific shear wave velocity testing. The soils encountered below the subject site are not susceptible to seismic liquefaction.

7 Page Soil Cover/Frost Protection It is recommended that perimeter footings (adjacent to a heated area) be provided with a minimum of 1.5 m of soil cover, or the equivalent combination of soil cover and foundation insulation, to provide adequate protection against frost action. Exterior unheated foundations, such as wing walls and canopy piers, if required, require additional protection to an equivalent of 2.1 metres of soil cover. The design of a foundation insulation layer (if required) can be provided by this firm, upon request, based on review of the plans. For conventional perimeter footings, having a minimum of 0.6 m of soil cover, a 50 mm thick layer of Styrofoam SM, or equivalent, can be placed down the exterior face of the foundation wall and extended outward to 1.2 metres beyond the exterior footing edge, to provide the required protection. 4.5 Slab-on-Grade/Building Pad Construction With the removal of any organic rich soil and/or existing fill materials, the existing fill, remnant soil and/or bedrock are suitable subgrade media on which to backfill for floor slab (or building pad) construction. All subgrade surfaces (except bedrock) should be thoroughly proof-rolled with appropriate compaction equipment prior to the placing of granular fill materials. Well-graded granular material of at least Granular B Type I quality, and preferably Granular B Type II is recommended for building up the grade under slabs-on-grade. It is recommended that the upper 150 mm to 200 mm of sub-slab fill consist of OPSS Granular A crushed stone material. These materials are to be compacted in uniform lifts to at least 95% of their standard Proctor maximum dry density (SPMDD) values. In the case of building pad preparation reference should be made for the requirements under the applicable agreement, as a more stringent compaction requirement, such as 98% of Standard Proctor maximum dry density, or 95% of Modified Proctor maximum dry density may be required. 4.6 Foundation Wall Drainage and Backfill It is routinely recommended by this firm that a perimeter foundation drainage system be provided for proposed structures. Such systems should consist of a 100 mm diameter "flexodrain" pipe, placed at the footing level around the exterior perimeter of the structure and surrounded by a 150 mm thick filter of 10 mm clear crushed stone. The pipe should have a positive outlet such as a gravity connection to the storm sewer.

8 Page 8 Perimeter drainage systems have not been provided for the existing City Walk structures and are not anticipated to be specified for the proposed structures, provided no basements are to be constructed. This is an acceptable practice, as the site has depressed groundwater conditions, provided that appropriate backfilling procedures are followed to prevent the potential for adfreezing frost action. Backfill against the sides of the foundation walls should consist of free-draining, non frost susceptible granular materials. The greater part of the existing fill materials are frost susceptible and, therefore, are not recommended for this purpose and imported materials, such as clean sand or OPSS Granular B Type I should be used. As an alternative, a geocomposite drainage membrane, such as System Platon or Miradrain, can be used in conjunction with the native fill. Where asphalt paving, interlock, concrete slabs-on-grade, or other hard landscaping will be located on the foundation wall backfill, it should be compacted in thin lifts to at least 95% of its SPMDD value. 4.7 Asphalt Pavement Construction The subject project is presently proposed to interfere very little with surrounding pavements and infrastructure. However, if and where reconstruction of asphaltic pavement is required, the following recommendations can be followed. Guidelines are also provided for hard landscaping elements. Recommended Minimum Pavement Material Thicknesses The uppermost inorganic in situ soil, inorganic fill materials, remnant pavement materials or bedrock are suitable subgrade media on which to commence backfilling for the granular subbase under areas to be paved. The recommended minimum pavement material thicknesses for parking (medium duty) and roadway/firelane (heavy duty) construction are summarized in Tables 1 and 2, on the following page. Select imported granular materials should be placed in thin lifts and compacted to at least 95% of their Standard Proctor maximum dry density values. It is recommended that Granular A and B Type II materials consist of crushed stone (B Type II is required by OPSS to consist of crushed stone) rather than crushed sand-gravel, because crushed stone materials have significantly better structural qualities than sand-based materials.

9 Page 9 Table 1 - Recommended Pavement Structure - Car Only Parking Thickness mm Material Description 50 WEAR COURSE - SP 12.5 Asphaltic Concrete (or HL-3) 150 BASE - OPSS Granular A Crushed Stone 300 SUBBASE - OPSS Granular B Type II SUBGRADE - Either in situ inorganic soil or bedrock, proof-rolled existing fill materials or OPSS Granular B Type II material placed over in situ soil or proof-rolled existing fill. Table 2 - Recommended Pavement Structure - Access Lanes and Fire Lanes Thickness (mm) Material Description 40 Wear Course - SP 12.5 Asphaltic Concrete (or HL-3) 50 Binder Course - SP 19.0 Asphaltic Concrete (or HL-8) 150 BASE - OPSS Granular A Crushed Stone 375 SUBBASE - OPSS Granular B Type II SUBGRADE - Either in situ inorganic soil or bedrock, proof-rolled existing fill materials or OPSS Granular B Type II material placed over in situ soil or proof-rolled existing fill. Paving Stone Areas In hard surfaced areas where paving stone will be used, and will be loaded by vehicle traffic, a base layer (150 mm thick) of OPSS Granular A over a 300 mm layer of OPSS Granular B Type II is recommended. Minimum Granular Base Thickness Where bedrock is the subgrade medium, it is recommended that a minimum combined granular base and subbase thickness of 300 mm be maintained. The material can either consist of 150 mm of Granular A over Granular B Type II, or Granular A in its entirety, whichever option is more convenient at the time. The subgrade should be shaped, or provided with subdrains or a shatter zone to ensure drainage.

10 Page 10 Transition Point Treatment Where the bedrock subgrade surface drops off at a slope in excess of 5H:1V a transition point treatment should be provided at the location where the subgrade medium changes from bedrock to soil. It is recommended that the bedrock subgrade be followed to a depth of at least 1.0 m below the routine subgrade level and that a taper of 5H:1V (i.e. up and away from the bedrock) be provided in the soil subgrade from that location to meet the routine subgrade level. The subgrade level in this location should be re-established with Granular B Type II. The net effect of the transition point treatment will be that the granular subbase thickness of the pavement will increase uniformly toward the bedrock subgrade location, in order that the differential settlement between the soil supported pavement and the relatively immobile bedrock supported pavement should occur over a smoother transition rather than creating a bump. Obviously the effectiveness of the transition point treatment is enhanced by maximizing the depth and/or minimizing the slope of the taper. 4.8 Site Servicing Bedding Conditions for Services The bedding conditions for services in the in situ soil, compacted fill and bedrock deposits are generally acceptable. Class "B" bedding is suitable for the support of service pipes in trenches through the above mentioned material. Below the groundwater level, 10 mm clear crushed stone is recommended for use as the granular bedding material if bedding cannot be placed in the dry (i.e. if pumping cannot control groundwater influx). Where a transition between soil and bedrock pipe bedding subgrade media is encountered during servicing, the transition should be investigated by geotechnical field review personnel to determine whether there is a need for transition treatment. This would consist of increasing the granular bedding thickness on the deeper bedrock side of the transition (following the bedrock), and then tapering the bedding thickness gradually (5H:1V) to the routine bedding thickness. Backfill of Trenches in Soil Provided the moisture content of the subject soils are not excessive, site excavated fill and soil will be suitable for re-use as backfill in the service trenches. The fine grained particle size of the silty sand, as well as the cohesive soils, will make compaction of these materials somewhat more difficult.

11 Page 11 Since services will likely be installed by "cut and cover" methods, it should be easy to ensure that site excavated soils used for trench backfill will be more or less of the same composition as the adjacent soil (i.e. sandy silt as backfill in areas of existing sandy silt, etc.) to provide for similar frost heave characteristics. Any boulders and organic material should be removed, prior to, or during, backfilling operations. Cohesive soils should be compacted utilizing "sheepsfoot" or "padfoot" type compaction equipment. A minimum field density of 95% of the standard Proctor dry density at the in situ water content is recommended to reduce differential settlement occurring between the trench and the adjacent unexcavated subgrade. The compactive effort required to compact the fill material is expected to be comparable to that required to compact Granular B Type I material, provided groundwater influx is not a problem. Should the use of site excavated fill as trench backfill material be found to be economically unviable, OPSS Granular B Type I material should be utilized. If OPSS Granular B Type I trench backfill is used in areas of frost susceptible subgrade (i.e. existing fill material), the upper 0.5 m to 1.0 m of the trench should be cut back at a slope of 5H:1V to 10H:1V to minimize the effects of differential frost heave. No such transitions are required where fill material is used as backfill in areas of existing fill subgrade provided they have similar gradations. The OPSS Granular B Type I should be compacted with conventional compaction equipment to a minimum field density of 95% of standard Proctor maximum dry density. Backfill of Trenches in Bedrock Site excavated bedrock is suitable for use as trench backfill provided it is adequately fragmented to provide a densely graded fill material. Otherwise it is recommended that OPSS Granular B Type I material be placed and compacted to at least 95% of the standard Proctor maximum dry density in trenches through bedrock. Where open-graded blast-rock fill is used as backfill material, it should be separated from adjacent finer materials with a woven geotextile, such as Amoco 2002, Terrafix Terratrack 24-15, or equivalent, in order to prevent the loss of fines from the overlying fill into the voids in the blast-rock. The use of a blinding course of OPSS Granular B Type II would also be beneficial.

12 Page Bedrock Removal Bedrock removal may be locally required for the Block S building and its site services. The sandstone bedrock underlying the site can be expected, for the greater part, to be relatively difficult to remove. Where the bedrock was encountered at shallow depth, in the investigations, its surface could be augered. As such, peeling off a thin weathered surficial layer with a hydraulic shovel, or locally hoe-ramming should be more practical and economical for shallow excavations for footings, where required to provide the minimum soil cover. Where deeper excavations are required, bedrock removal using conventional drilling and blasting techniques would be the most economical method of removing the bedrock. However, a pre-blast survey of adjacent structures and tight blast control would be required to minimize blast-related vibrations. It is recommended that all bedrock removal by blasting techniques be undertaken prior to the start of foundation construction for a particular structure. Otherwise, restrictions on blasting adjacent to green concrete would have to be implemented. The use of hoe ramming techniques would be preferable to blasting, from a vibration standpoint, but the economics of this method will depend on the bedrock removal quantities, especially with respect to the depth/thickness involved Design and Construction Precautions Excavation Side Slopes The sides slopes of excavations in the soil and fill overburden materials should either be cut back at acceptable slopes or should be retained by shoring systems from the start of the excavation until the structure is backfilled. It is assumed that sufficient room will be available for all the excavations to be undertaken by open-cut methods (i.e. unsupported excavations). The excavation side slopes should be cut back at 1H:1V and slopes in excess of 2 m depth should be protected with securely fastened tarps to retard the desiccation of the soil and to control ravelling of the surface of the slope. Excavated soil should not be stockpiled at the top of excavations and heavy equipment, should be kept away from the excavation sides.

13 Page 13 It is recommended that a trench box be used at all times to protect personnel working in trenches with steep or vertical sides. It is expected that services will be installed by cut and cover methods and excavations will not be left open for extended periods of time. Groundwater Control Although groundwater is not expected to be a serious problem during construction of the foundations, the contractor should be prepared to direct water away from all bearing surfaces and subgrades, regardless of the source, to prevent disturbance to the founding and/or subgrade media and to allow for proper inspections to be conducted. Winter Construction In the event of footings being constructed during the winter months, founding media are required to be protected from freezing temperatures by the use of straw, propane heaters or other suitable means. In this regard, the base of the excavation should be insulated from below freezing temperatures immediately upon exposure, until the time that footings have sufficient soil cover to prevent freezing of the subsoils, and heat is provided to the structures. The placing of fill materials during cold weather also requires the implementation of a strict procedure of bringing unfrozen materials to the site, placing and compacting them prior to their freezing and protecting the surface from freezing until the following lift is to be placed. All materials are to be placed and compacted after being delivered and are not to be stockpiled and allowed to freeze prior to being placed. 5.0 Field Review and Testing Services It is a requirement, for the foundation design data provided under Section 4.2 of this report, and the other design data provided herein, to be applicable, that the following inspection program be carried out by the geotechnical consultant. Field review of all bedrock and engineered granular fill bearing surfaces prior to the placement of concrete for footings. Field review of transitions between bedrock and other bearing media and provision of recommendations for transition point treatment if and as required. Conducting of field density testing to ensure that the specified level of compaction has been achieved in all fill materials, including engineered granular fill.

14 Page 14 Sampling and testing of the concrete used for structural building components. Concrete testing for structures, curbs and sidewalks. Asphalt compliance testing for paved areas. The completion of an inspection program of this nature will result in the issuance of a report confirming that these works have been carried out in the prescribed manner, according to our recommendations, if requested by the client. 6.0 Statement of Limitations The client should be aware that any information pertaining to soils and all test hole logs are furnished as a matter of general information only and test hole descriptions or logs are not to be interpreted as descriptive of conditions at locations other than those described by the test holes themselves. A site investigation of this nature is a limited sampling of a site. The conclusions are based on information gathered at the specific test locations and can only be extrapolated to an undefined limited area around the test locations. The extent of the limited area depends on the soil, bedrock and groundwater conditions, as well the history of the site reflecting natural, construction, and other activities. Should any conditions at the site be encountered which differ from those at the test locations, we request that we be notified immediately in order to permit reassessment of our recommendations. The present report applies only to the project described in this document. Use of this report for purposes other than those described herein or by person(s) other than Kanata Entertainment Holdings Inc., PenEquity Realty Corporation, or their agent(s) is not authorized without review by this firm for the applicability of our recommendations to the altered use of the report.

15 Page 15 We trust this submission meets your requirements. Should you have any questions, please do not hesitate to contact our office. Best Regards, Paterson Group Inc. Andrew J. Tovell, P.Eng. Attachments: Soil Profile and Test Data sheets (11 pp) Drawing No. PG2637-1: Test Hole Location Plan

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