February 22, 2016 AG File No

Size: px

Start display at page:

Download "February 22, 2016 AG File No"

Donna Payne
5 years ago
Views:

1 Ainley Graham & Associates Limited 1-50 Grant Timmins Drive, Kingston, Ontario, K7M 8N2 Tel: (343) Fax: (343) February 22, 2016 AG File No Ministry of Transportation 347 Preston Street, 4 th Floor Ottawa, Ontario K1S 3J4 Attention: Mr. Tom Kelly, General Coordinator Re: Johnstown Patrol Yard GWP Geotechnical Investigation Report Dear Mr. Kelly: Ainley Group (Ainley) was retained by the Ministry of Transportation (MTO), to carry out geotechnical consulting services in support of the redevelopment for the above noted site. It is our understanding the yard redesign will be based on the construction of a new fabric coverall building to replace an existing salt and sand storage structure. The objectives of the geotechnical component of this assignment were: To obtain subsoil information within the area of the proposed redevelopment. To prepare a geotechnical report summarizing the results of the borehole investigation and provide recommendations with respect to shallow foundations, pavement structure, utility trenching, excavations and groundwater control to advance the design and construction of the new fabric coverall building. SITE DESCRIPTION The Johnstown Patrol Yard is located at 2542 Rooney Road, Johnstown, on the northeast side of the Highway 16 and Highway 401 interchange (I/C #721). The site can be accessed directly off of Rooney Road through a gated entrance. The area around the site is predominantly wooded, with a gas station, truck stop, and scales to the northwest of the site on Rooney Road. Onsite there are currently two salt sheds, one salt/sand dome, a brine tank, and multiple fuel tanks. There is a large paved area for parking just inside the entrance, with pavement extending from the parking lot northeast around the salt/sand dome. The proposed building is to be constructed where the existing salt dome is, at the centre of the property on the paved area. The salt sheds and tanks sit on the northwest side of the paved area to the west of the salt/sand dome. Drainage appears to be directed to the east edge of the site, outletting into a low lying wetland area behind the site. A site and borehole location plan is attached to this report as Figure No. 1.

2 Johnstown Patrol Yard GWP Geotechnical Investigation Report AG File No FIELDWORK / METHODOLOGY The fieldwork for the investigation was conducted in general accordance with the terms provided to our office by MTO. The field program consisted of the advancement of seven (7) boreholes (BH1 BH7) to investigate the sub-surface conditions. Prior to commencing the geotechnical investigation program, Ainley requested the clearance of all underground utilities within the area of the proposed drill locations prior to advancing the field program. The borehole program was completed on January 25th, 2016, under the constant supervision of a qualified member of Ainley s geotechnical staff. The boreholes were advanced throughout the proposed redevelopment area as shown on Figure 1. The boreholes were advanced to maximum depths of 3.0 m below the ground surface. The boreholes were advanced by means of a truck-mounted CME-55 drill rig equipped for soil and rock sampling. Split spoon sampling procedures were performed within the boreholes to determine the penetration resistance (in terms of N values, Standard Penetration Index) of the existing subsoils. The values obtained may be correlated to the relative density of non-cohesive materials and consistency of cohesive soils. Upon completion of the boreholes each borehole was backfilled and compacted with native material and the asphalt was patch with cold patch and compacted. Representative samples of the subsoil materials encountered were secured within each borehole for further review and selection for laboratory analysis. Groundwater infiltration was monitored during the borehole program however long term monitoring of the groundwater conditions was outside the scope of the assignment. The borehole locations and elevations were surveyed geodetically by other members of the Ainley design team and the information provided for incorporation into this report. RESULTS OF THE INVESTIGATION Full details of the subsurface conditions encountered at the borehole locations are presented on the individual borehole logs included as Enclosure 1. It is emphasized however, that the soil types, their sequence, thickness and physical properties may vary between test locations and samples both vertically and horizontally. Representative samples of the subsoil materials encountered within the boreholes were collected and returned to our office for further visual review by an engineer having experience with soil classification and identification. A total of seven (7) samples were selected and submitted to an accredited laboratory for gradation analysis and moisture content determination. Copies of the Grain Size Distribution results are included in Enclosure 2. The subsoil conditions encountered throughout the site generally consisted of the following:

3 Johnstown Patrol Yard GWP Geotechnical Investigation Report AG File No Topsoil A 100 mm thick layer of silty sand topsoil was encountered in BH1. Topsoil was not encountered in any of the remaining boreholes. Asphalt A 50 mm to 75 mm thick layer of asphalt was encountered within BH Nos. 2, 3 and 6. The average pavement thickness was found to be approximately 65 mm. Fill A layer of silty sand, trace of gravel and clay, in a loose state of consistency was found in BH1 to a depth of 0.90 m, upon which inferred bedrock was encountered. A representative sample of the silty sand, trace of gravel and clay was submitted for gradation and moisture content determination. The percentage of material passing the 4.75 mm and 75 µm sieves was found to be 99.0 and 27.6 respectively. The moisture content was found to be 23.4% at the time of the site investigation. Fill A layer of sand with gravel fill material was found in all boreholes except BH1. The sand with gravel material was encountered immediately underlying the asphalt in BH Nos. 2, 3 and 6, and immediately below the ground surface in BH Nos. 4, 5 and 7. The sand with gravel fill was found to be in a compact state of consistency at the time of the field investigation. The sand fill extended to depths ranging from 0.15 m to 0.30 m below existing site grades with an average thickness of approximately 0.16 m. One representative sample of the sand with some gravel was submitted for gradation and moisture content determination. The percentage of material passing the 4.75 mm and 75 µm sieves was found to be 75.8 and 5.7 respectively. The moisture content was found to be 6.7% at the time of the site investigation. Fill A layer of sand with varying amounts of gravel and cobbles was encountered underlying the sand with gravel fill material in all boreholes with exception to BH No. 1. The material varied from sand, trace of gravel to sand, some gravel and cobbles, and was found to be in a loose to compact state of consistency at the time of the site investigation. The sand with varying amounts of gravel and cobbles extended to depths ranging from 0.45 m to 1.0 m below existing site grades with an average thickness of approximately 0.75 m. In BH Nos. 2 and 3, the fill layer extended down to 1.0 m where bedrock was encountered. One representative sample of the sand with varying amounts of gravel and cobbles was submitted for gradation and moisture content determination. The percentage of material passing the 4.75 mm

4 Johnstown Patrol Yard GWP Geotechnical Investigation Report AG File No and 75 µm sieves was found to be 96.3 and 21.3 respectively. The moisture content was found to be 12.9% at the time of the site investigation. Fill A layer of sand with varying amounts of silt and gravel fill was encountered underlying the sand with varying amounts of gravel and cobbles fill within BH Nos. 4 to 7. The sand with varying amounts of silt and gravel fill was found to in a loose state of consistency at the time of the site investigation. The sand with varying amounts of silt and gravel fill extended to depths ranging from 1.5 m to 2.4 m below existing site grades with an average thickness of approximately 0.9 m. Fibrous organics were encountered within the fill layer in BH4. Four representative samples were submitted for gradation and moisture content determination. The percentage of material passing the 4.75 mm and 75 µm sieves were found to range from 73.9 to 93.2 and 12.4 to 30.1 The moisture contents were found to range from 8.8% to 18.8% respectively at the time of the site investigation. Peat A layer of peat was found underlying the fill materials within BH5. The peat was encountered at a depth of 2.0 m to 2.2 m below existing site grades. Sand A layer of sand with gravel was encountered underlying the peat material in BH5, in a loose state of consistency. The sand layer was encountered at a depth extending to 2.5 m where refusal on inferred bedrock occurred. Bedrock Refusal to advance the soils equipment on the inferred bedrock surface was encountered within all boreholes at depths (elevations) ranging from 0.9 m to 2.5 m (96.92 masl to 99.0 masl) below existing grade. Groundwater Groundwater infiltration was encountered at the time of the field investigation within BH Nos. 1, 2 and 4 at depths (elevations) ranging from 0.85 m to 1.1 m below existing site grades (97.89 m to m). DISCUSSION AND RECOMMENDATIONS It is our understanding that the purpose of the geotechnical investigation and report is to provide recommendations based on the engineering properties of the subsoil materials encountered to advance the design and construction of the proposed site redevelopment (new coverall structure and asphalt reinstatement).

5 Johnstown Patrol Yard GWP Geotechnical Investigation Report AG File No Foundations Results of the drilling program revealed that there is one (1) predominate founding soil layer across the site suitable for the placement of shallow spread and strip footings, namely the underlying bedrock surface. Foundations placed directly on the bedrock surface may be designed using a bearing capacity of 500 kpa (ULS). Settlement of the bedrock surface is considered negligible. The bedrock surface should be clean, free of loose fragments and have a slope of no more than 15%. All loose and weathered rock should be removed from the bearing surface. Alternatively, foundations may be placed on properly constructed engineered fill built up from the sound bedrock surface. Engineered fill should consist of granular material approved by the engineer and compacted to 100% Standard Proctor Maximum Dry Density (SPMDD). The engineered fill material should be placed in lifts compatible with the compaction equipment used. A quality control technician, should monitor the placement of the engineered fill material and the compaction densities for each lift to ensure that proper compaction efforts have been achieved. Foundations placed on properly constructed engineered fill built up from the sound bedrock surface may be designed using an SLS pressure of 200 kpa and ULS pressure of 400 kpa. Total and differential settlements for foundations placed on properly constructed engineered fill should not exceed 25 mm and 19 mm respectively. Should footings bear partially on bedrock and partially on engineered soils then structural provisions should be provided in order to accommodate for differential settlements that may occur between the two. All exterior footings for unheated structures must be protected by a minimum of 1.5 m of earth cover or equivalent, and 1.2 m for heated structures in order to provide protection against detrimental frost action unless placed on proven sound bedrock. For foundations placed on the bedrock surface at a finished grade less than the minimum cover recommended the soundness of the rock could be determined by means of probe holes along the exterior footing location using an air-track type drill before construction. The presence of frost susceptible voids and mud seams could then be determined. Alternatively, using insulation material placed over the concrete foundation wall and below the slab base course could also be considered. Slab-on-Grade It is recommended that all surficial topsoil and fill materials be removed to reveal the bedrock surface encountered throughout the proposed building site. Normal slab-on-grade construction can be carried out as follows: a) Remove all surficial topsoil and fill materials to expose the underlying bedrock surface. b) Build up granular fill materials from the approved bedrock surface by placing Granular B Type II material in lifts suitable with the compaction equipment used to achieve a minimum of 100% SPMDD. A capillary moisture barrier consisting of either 19 mm clear crushed stone or Granular A is recommended at least 200 mm thick immediately underlying the

6 Johnstown Patrol Yard GWP Geotechnical Investigation Report AG File No slab. The 200 mm thick Granular A is also recommended for fine grading purposes and to provide a uniform bearing surface for the concrete slab. Under floor drains are not considered necessary providing the slab is set a minimum of 0.3 m above finished exterior grades for structures without a basement. Should the floor slab not meet the assumed criteria than it is recommended that under floor drainage also be provided. Groundwater Control/Subsurface Drainage Based on the observations made during the field investigation perched groundwater infiltrations may be encountered within excavations, however it should be noted that groundwater levels will fluctuate seasonally and also during periods of drought and precipitation. Development areas within the site should be graded in the early stages of construction to provide for positive runoff of all surface water. The pumping of groundwater may be required during excavation of the shallow overburden. Normal pumps should suffice but filters may be required to prevent clogging of the pumps. The groundwater level should be controlled at all times and be kept below the excavation level during the construction period. Excavations All excavations should be carried out in accordance with the provisions in the Occupational Health and Safety Act. At the time of the field investigations the sub-soil materials encountered across the site can be classified as follows: The fill materials may be classified as Type 3 soil. The bedrock may be classified as Type 1 soil. Shallow excavations into the soils are considered straightforward and conventional excavation techniques and equipment appropriate. Lateral Earth Pressure Coefficients The following parameters may be used to determine lateral earth pressures: Soil Type Unit Weight dry (kn/m 3 ) Angle of Internal Friction ( ) Coefficient of Earth Pressure at Rest (Ko) Granular A Granular B Silty Sand

7 Johnstown Patrol Yard GWP Geotechnical Investigation Report AG File No Suitability of Material The fill and sand materials encountered across the site may be reused for grading operation outside the building envelope and foundation walls. A maximum particle size of 100 mm is recommended for backfill used against foundation walls. The subsoils are considered suitable for reuse as subgrade material below exterior paved areas or in utility trenches. It is recommended that moisture contents in the soils be closely monitored when they are to be used as select subgrade fill or as a founding soil during construction. Wet soils should not be placed as backfill, subgrade fill or utilized as a founding material under any circumstances. Utility Trenches The construction of proposed utility trenches to service the proposed structure should consist of removal of the existing overburden soils to achieve the required grades. Based on the soils information obtained from the site utility pipes will be installed in fine-grained subsoil trenches. Bedding for the pipes should consist of 150 mm Granular A material. The bedding should be placed in lifts compatible with the compaction equipment used to achieve 100% SPMDD. Backfill around the pipes should consist of Granular A material with a minimum cover thickness of 300 mm over the obvert of the pipe. The backfill should be compacted to 100% SPMDD. In order to reduce the potential for differential settlements it is recommended that the backfill materials within the frost penetration zone of 1.5 m below finished grade be practically suitable to the existing soil profile. If imported backfill including granular materials are used then the excavation side slopes should have frost tapers in accordance with applicable Ontario Provincial Standards (OPSD 802 series drawings and OPSS 401). Pavement Design It is recommended that the following pavement structure be utilized for reinstatement of the site based on the anticipated loading. It should be noted however that the recommended pavement structure noted below is based on all topsoil, organic and unsuitable materials being removed to reveal the underlying compact sand fill. It is recommended that the subgrade material be proof rolled prior to placement of the granular subbase to reveal any soft/loose areas. Any areas exhibiting rutting or appreciable deflection should be excavated and replaced with suitable fill material compacted to a minimum of 95% SPMDD. 50 mm HL3 Surface Course, over 50 mm HL8 Binder Course, over 200 mm Granular A, over 300 mm Granular B Type II

8 Johnstown Patrol Yard GWP Geotechnical Investigation Report AG File No Granular A and Granular B Type II used for base and subbase material shall meet the requirements of OPSS 1010 and shall be compacted to 100% SPMDD. Inspection by qualified geotechnical personnel should be carried out during the construction process to verify the competence of the subgrade material and to verify the compaction densities of both the subbase and base course materials. Site Inspections It is recommended that all foundation and subgrade materials be inspected by qualified geotechnical personnel prior to the placement of concrete for footings, in order to ensure that the materials and founding elevations are consistent with the recommendations of this report. It is also recommended that the placement and compaction of all fill soils be monitored and tested by qualified geotechnical personnel to ensure that the appropriate materials and compaction densities are achieved. CLOSURE The Limitations of Report attached, form an integral part of this report. We trust this report provides sufficient information for your present requirements in accordance with our Statement of Work. We trust this report is to your satisfaction. Should you have any questions concerning the above, please feel free to contact our office. Sincerely, AINLEY GRAHAM & ASSOCIATES LIMITED Lois-Ann L. Hayes P.Eng. Senior Project Engineer

9 Johnstown Patrol Yard GWP Geotechnical Investigation Report AG File No Limitations of Report The conclusions and recommendations given in this report are based on information determined at the borehole locations. Subsurface and groundwater conditions between and beyond the test holes may differ from those encountered at the test locations, and conditions may become apparent during construction, which could not be detected or anticipated at the time of the site investigation. It is recommended practice that the Soils Engineer be retained during construction to confirm that the subsurface conditions throughout the site do not deviate materially from those encountered in the boreholes. The comments made in this report are intended only for the guidance of the designer. The number of test holes may not be sufficient to determine all factors that may affect construction methods and costs. The contractors bidding on this project or undertaking the 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. This report has been prepared for design purposes, for the sole use of the Ministry of Transportation. Any uses, which a Third Party makes of this report, or any reliance or decisions to be made based on it, are the responsibilities of said Third Parties. Ainley Group accepts no responsibility for damages if any, suffered by any Third Party as a result of decisions made or actions based on this report.

10 Johnstown Patrol Yard GWP Geotechnical Investigation Report AG File No Figure No. 1 Site and Borehole Location Plan

BOREHOLE ID BOREHOLE TABLE ELEVATION (m) GRADE BEDROCK GROUNDWATER BH1 99.90 99.00 99.05 BH2 100.02 98.

11 BOREHOLE ID BOREHOLE TABLE ELEVATION (m) GRADE BEDROCK GROUNDWATER BH BH BH NA BH BH NA BH NA BH

12 Johnstown Patrol Yard GWP Geotechnical Investigation Report AG File No Enclosure 1 Borehole Logs

20 Johnstown Patrol Yard GWP Geotechnical Investigation Report AG File No Enclosure 2 Grain Size Distribution Results

ATTACHMENT A PRELIMINARY GEOTECHNICAL SUMMARY

ATTACHMENT A PRELIMINARY GEOTECHNICAL SUMMARY Kevin M. Martin, P.E. KMM Geotechnical Consultants, LLC 7 Marshall Road Hampstead, NH 0384 603-489-6 (p)/ 603-489-8 (f)/78-78-4084(m) kevinmartinpe@aol.com