Geotechnical Investigation, Hydrogeological Review, Materials Testing & Inspection

About the project

PNJ Engineering Inc. (PNJ) was retained by Elite Construction (Client) to undertake geotechnical and hydrogeological investigations for the proposed building addition at 88 St. Regis Crescent South, North York, Ontario (Site). The study was required to support the site plan application and detail design. The purpose of the geotechnical investigation was to assess the subsurface soil and groundwater conditions in the proposed development through 5 sampled boreholes and provide comments and recommendations for design and construction. The anticipated construction conditions pertaining to excavation, seismic site classification, backfilling and groundwater control are also discussed in this report, but only regarding how these might influence the design. The hydrogeological investigation was carried out in conjunction with the geotechnical investigation by PNJ. The hydrogeological investigation was completed in accordance with the following regulatory requirements:

• Ontario Water Resources Act (OWRA)
• Ontario Regulation (O.Reg.) 63/16
• Ontario Regulation (O.Reg.) 387/04

During the study a review of available background geologic and hydrogeological information for the site and the surrounding areas was conducted. This provided background information to allow for characterization of regional hydrogeological conditions. In addition, site visits were made by the project hydrogeologist to inspect and confirm the existing Site conditions, including topography, drainage and geomorphology. The subsurface investigation of the Site was conducted concurrently as part of the geotechnical and hydrogeological investigations. The subsurface investigation included the drilling of five (5) exploratory boreholes. Four (4) boreholes were drilled up to a maximum depth of 6.7 m below grade (mbgs), and one (1) borehole was drilled to a maximum depth of 12.8 m bgs. All five (5) boreholes were equipped with monitoring wells to assess groundwater levels and its quality at the Site. In-situ hydraulic conductivity tests were conducted in all the five (5) monitoring wells to assess hydraulic conductivity of the subsurface soils and to evaluate the hydraulic characteristics of the geological sediments and the potential dewatering requirements. Ground water levels were monitored in the monitoring wells. In compliance with City of Toronto Terms of Reference (ToR), bi-weekly groundwater monitoring in all the five (5) monitoring wells was completed for a period of 3-months. One (1) set of ground water sample was collected to test water quality parameters included in the Toronto Sanitary and Combined Sewer and Storm Sewer By-Law criteria. This information was used to determine the water quality and the suitability of the water for discharge to local sewers. Based on the site conceptual plans and site survey plans, a pre- and post-development water balance assessment was carried out to determine the change in the infiltration rates to support any site stormwater management plan. An assessment to determine the requirements for groundwater control and dewatering during the construction period for the installation of the shallow foundation of the proposed structure was carried out, including discussion on the need to obtain any water taking or water discharge permits.

We understand that the quality of fill materials to re-use for the backfilling at the construction site has a direct impact on its durability. Our team carried out construction materials testing on-site and, in the laboratory, in a prompt fashion allowing us to offer innovative timely solutions and prevent the use of materials that could compromise the integrity of the project. All field technicians used on this job are CCIL certified, and our laboratory testing is supervised by CCIL-certified technicians. The required material testing was carried out in compliant to OPSS 212 construction specification for earth borrow. 

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