Terraprobe

Transcription

Terraprobe

Terraprobe
Consulting Geotechnical & Environmental Engineering
Construction Materials Engineering, Inspection & Testing
PRELIMINARY
SUBSURFACE INVESTIGATION
TTC LFLRV MAINTENANCE
& STORAGE FACILITIES
LAKESHORE BLVD. E. & LESLIE STREET
TORONTO, ONTARIO
Prepared For:
AECOM
300 Water Street
Whitby, ON L1N 9J2
Attention: Mr. Joe Peristy
File No. 1-09-4138
October 1, 2009
© Terraprobe Limited
Distribution of Report:
2 copies -
AECOM
1 copy -
Terraprobe Limited
Terraprobe Limited
10 Bram Court
Brampton, Ontario L6W 3R6
(905) 796-2650 Fax: 796-2250
220 Bayview Drive, Unit 25
Barrie, Ontario L4N 4Y8
(705) 739-8355 Fax: 739-8369
1012 Kelly Lake Rd., Unit 1
Sudbury, Ontario P3E 5P4
(705) 670-0460 Fax: 670-0558
www.terraprobe.ca
903 Barton Street, Unit 22
Stoney Creek, Ontario L8E 5P5
(905) 643-7560 Fax: 643-7559
AECOM
TTC LFLRV Maintenance & Storage Facilities, Toronto, ON
October 1, 2009
File No. 1-09-4138
TABLE OF CONTENTS
1.0
PROJECT DESCRIPTION AND SCOPE OF WORK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2.0
SUBSURFACE CONDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.1
Stratigraphy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.1.1 Surface Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.1.2 Earth Fill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.1.3 Organic Silt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.1.4 Sand and Sand and Gravel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.1.5 Silty Clay Glacial Till . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.1.6 Bedrock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
2
2
2
3
3
3
4
3.0
DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1
Excavation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2
Fill and Soil Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3
Ground Water Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5
5
6
7
7
4.0
LIMITATIONS AND USE OF REPORT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.1
Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.2
Use of Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Appendices:
Appendix A - Borehole Logs 1 to 3 and A to H, and Test Trench Logs 1 to 4
Appendix B - Certificate of Chemical Analysis Tabulation to Table No. 1
Appendix C - Certificate of Chemical Analysis Tabulation to Table No. 3 (Soil)
Appendix D - Certificate of Chemical Analysis Tabulation to Table No. 1 & 3 (Water)
Appendix E - Summary of Field Investigation Protocol
Figures:
Figure 1 - Site Location Plan
Figure 2 - Borehole and Test Trench Location Plan
Figures 3 to 6 - Test Trench Plans and Profiles
Photographs
Terraprobe
1-09-4138-Oct-1-2009-TD-10_12-Prelim SUB Invest.wpd
Page No. i
AECOM
1.0
October 1, 2009
File No. 1-09-4138
PROJECT DESCRIPTION AND SCOPE OF WORK
Terraprobe Limited was retained by TTC through AECOM to carry out a preliminary subsurface investigation
at the potential site for a TTC LFLRV Maintenance and Storage Facility, 9 Leslie Street in Toronto, Ontario.
The site is vacant land on the northwest corner of the Ashbridges Bay Waste Water Treatment Plant. A site
location plan is provided on Figures 1 and 2. Most of the property is currently occupied by a fill mound of
approximately 15 m height. The site is generally covered with grasses.
The development of the site requires the removal of the large mound of fill from the property. The volume
of fill requiring removal is estimated as 455,000 m3. The purpose of the investigation was to characterize the
stratigraphy of the fill mound and the soil below. The investigative effort comprised 11 boreholes and 4 test
trenches used to sample and visually assess the fill. The investigative work was carried out from August 6
to 14, 2009; and on September 18, 2009.
The test trenches are denoted as T1 through T4. The boreholes are denoted as A through H, and 1 through 3.
Monitoring wells were installed in three selected boreholes (D, H and 3) to permit sampling of ground water
quality.
Generally, Boreholes A through H were drilled through the fill mound. Boreholes 1, 2 and 3 were drilled at
the northwest corner of the property, away from the fill mound.
This document presents the findings of the subsurface investigation. This document contains preliminary
information which is intended for initial planning and feasibility purposes. Further, more detailed studies and
engineering consultation will be required as the project proceeds.
Terraprobe
Page No. 1
AECOM
2.0
October 1, 2009
File No. 1-09-4138
SUBSURFACE CONDITIONS
The procedures used for the investigation, collection and handling of samples are documented in Appendix E.
The borehole and test trench locations are shown on Figure 2. The detailed results of the individual boreholes
and test trenches are recorded on the Borehole and Test Trench Logs in Appendix A. The ground surface
elevations at the borehole locations have been referenced to a geodetic datum.
2.1
Stratigraphy
2.1.1 Surface Materials
Topsoil was penetrated at the ground surface in all borehole locations except Borehole C. The thickness of
the topsoil layer varied from about 130 mm to 180 mm. The topsoil is dark brown to black in colour with a
sandy silt matrix.
2.1.2 Earth Fill
Beneath the topsoil layer, earth fill was penetrated to depths of 7.6 to 19.8 m below existing grade at the
locations of Boreholes A through H (i.e., on the fill mound). At the locations of Boreholes 1 through 3 (away
from the fill mound), the thickness of fill ranged from approximately 2.3 to 6.1 m.
The earth fill comprises loose to dense sand, silty sand and sandy silt with clayey silt layers/pockets. The
earth fill contains varying amounts of wood, glass, paper, cardboard, plastic, rubber, brick and concrete
debris/rubble mixed with dark grey/black organic matter. The test trench excavation revealed large pieces of
concrete, block, timber, clay pipe, rebar and tires. Evidence of ash, coal, and peat were found in the lower
parts of the mound. The fill is generally dark grey to black and within certain horizons there are hydrocarbon
odours.
Based on the results of the borehole and test pit investigation, it appears that the fill consists mostly of a
matrix of common earth (silty sand to clayey silt) mixed with varying amounts of building rubble and debris.
The material is extremely variable in both physical composition and consistency.
The fill depths are tabulated as follows:
Borehole
Existing Ground
Surface Elev. (m)
Depth of Fill (m)
Approx. Base of Fill
Elev. (m)
A
88.8
13.4
75.4
B
86.8
16.8
70.0
C
93.2
16.8
76.4
Terraprobe
Page No. 2
AECOM
October 1, 2009
File No. 1-09-4138
Borehole
Existing Ground
Surface Elev. (m)
Depth of Fill (m)
Approx. Base of Fill
Elev. (m)
D
83.2
12.2
71.0
E
90.9
19.8
71.1
F
91.2
19.8
71.4
G
85.9
13.7
72.2
H
79.0
7.6
71.4
Figures 3 to 6 inclusive provide the results of the test trench works. Selected photographs illustrate the nature
of the earth fill and inclusions as revealed by the test trenches.
2.1.3 Organic Silt
Beneath the earth fill layer, organic silt was penetrated at depths of 7.6 to 19.8 m below existing grade in all
boreholes except Borehole A. Borehole A reached auger refusal in the earth fill material at a depth of 13.4 m
below grade and did not reach the silt layer. The organic silt was greyish brown, generally loose or soft, and
high in moisture content which is indicative of material of organic content.
2.1.4 Sand and Sand and Gravel
The organic silt was underlain by a layer of sand and sand and gravel at a depth of 21.3 m below grade in the
Borehole B location. This cohesionless soil deposit was greyish brown, dense to very dense and wet.
2.1.5 Silty Clay Glacial Till
The sand layer in Borehole B was underlain by silty clay glacial till. This deposit has a predominantly silty
clay matrix with embedded sand, gravel, cobbles and boulders. The till had a hard/dense consistency.
2.1.6 Bedrock
The glacial till is underlain by bedrock of the Georgian Bay Formation. The bedrock of the Georgian Bay
Formation is a deposit predominantly comprised of thin to medium bedded grey shale.
Terraprobe
Page No. 3
AECOM
2.2
October 1, 2009
File No. 1-09-4138
Ground Water
Observations pertaining to the depth of water level were made in the open boreholes immediately after
completion of drilling. Observation wells were installed in Boreholes D, H and 3.
The water level measurements taken in the open boreholes and observation wells are summarized as follows:
Borehole
No.
Existing
Ground
Surface
Elev. (m)
Depth of
Borehole
(m)
A
88.2
B
Upon Completion of Drilling
Water Level in
Monitoring Well
Depth to Cave
(m)
Depth to Water
(m)
Depth to
Water (m)
Elev. to
Water (m)
13.4
12.5
9.4
NW
NW
86.8
28.7
n/a
n/a
NW
NW
C
93.2
18.8
Wet cave at 12.5
n/a
NW
NW
D
83.2
12.7
10.4
8.5
7.2
76.0
E
90.9
20.3
13.7
9.5
NW
NW
F
91.2
20.3
14.6
9.8
NW
NW
G
85.9
15.7
9.3
7.8
NW
NW
H
79.0
9.6
8.2
7.3
3.7
75.3
1
77.0
8.1
4.0
3.0
NW
NW
2
77.5
8.1
6.4
2.7
NW
NW
3
76.5
8.1
Open
2.3
2.1
74.4
Terraprobe
Page No. 4
AECOM
3.0
October 1, 2009
File No. 1-09-4138
DISCUSSION
The following discussion is provided for preliminary planning and feasibility purposes. This discussion is
provided based on our current understanding of the project. We understand the project will generally involve
removal of the existing fill mound at site, and construction of the facility. The facility will consist of a large,
flat yard area for access and maintenance of light rail vehicles. A large, slab-on-grade maintenance building
will also be constructed. It is anticipated that the existing fill mound will be removed, and the site grades will
be similar to the existing street grades on adjacent Lakeshore Boulevard and Leslie Street. Excavations will
generally not extend more than 3 m below the adjacent street grades. Excavations will generally be limited
to the installation of underground utilities and services. A fill berm or mound of several metres height will
be left in place along Lakeshore Boulevard as a buffer.
3.1
Excavation
Excavations must be carried out in accordance with the Occupational Health and Safety Act and Regulations
for construction projects. These regulations designate four broad classifications of soils to stipulate
appropriate measures for excavation safety. For practical purposes all of the material found on the site is a
Type 3 soil where it is above the ground water, and it is a Type 4 soil where it is below the ground water.
Where workmen must enter a trench or excavation deeper than 1.2 m, the trench or excavation must be
suitably sloped and/or braced in accordance with the regulation requirements. The regulation stipulates
maximum slopes of excavation by soil type as follows.
Soil Type
Base of Slope
Maximum Slope Inclination
3
from bottom of trench
1 horizontal to 1 vertical
4
from bottom of trench
3 horizontal to 1 vertical
Minimum support system requirements for steeper excavations are stipulated in Sections 235 through 238,
and 231 of the Act and Regulations, and include provisions for timbering, shoring and moveable trench
boxes, where sloped excavation slopes cannot be used.
It is noted the above recommendations apply to relatively shallow excavations (typically less than 3 m below
the surrounding grade). As a result of the soft/loose nature of the fill and organic materials at the site, special
considerations will apply to deeper excavations. In addition, excavations conducted directly adjacent to the
fill mound will require special consideration to ensure their stability.
Terraprobe
Page No. 5
AECOM
3.2
October 1, 2009
File No. 1-09-4138
Fill and Soil Quality
Thirty-six samples of soil were analysed to assess soil quality. The samples were analysed for a range of
parameters which may be indicative of impact found in fill materials in the Toronto area. These include:
•
•
•
•
•
Petroleum hydrocarbons
Metal and inorganic parameters
Volatile organic compounds
Polyaromatic hydrocarbons
PCB
The laboratory results were compared to the Soil and Sediment Standards found in Ontario
Regulation 153/04. The results were compared to the following Standards:
•
Table 1 Standard. This generally represents the most strict Standard for soil quality in the
regulation. Soil meeting Table 1 is chemically suitable for use as fill material under almost
all circumstances and for all sites.
•
Table 3 (Residential) Standards. Soil meeting the Table 3 Standards is chemically suitable
for use as fill on most properties within the GTA.
Soil which exceeds the Table 3 Standards is generally not suitable for fill in the GTA. Typically, soil which
exceeds the Table 3 Standards must be treated as a waste material and disposed of at an approved fill
management or waste disposal site.
The results of the analysis are presented as follows:
•
•
Appendix B. Results are tabulated relative to Table 1 Standards.
Appendix C. Results are tabulated relative to Table 3 (Residential) Standards.
The results indicate that the fill materials at the site consistently exhibit exceedances of the Tables 1 and 3
Standards. These exceedances are most frequently for metals, polyaromatic hydrocarbons, and occasionally
for petroleum hydrocarbons. There were a few exceedances for volatile organic compounds. It is noted that
some of the samples assessed for VOC were retained longer than the stipulated holding time before analysis
because of a delay in the site drilling and sorting of the samples. The results for these samples are for
discussion purposes only and are not definitive.
The most frequent exceedances for metals included lead and zinc, while the most frequent exceedance for
polyaromatic hydrocarbons was benzo(a)pyrene. PCB compounds were not detected.
Eleven of the soil samples submitted to the laboratory and found to contain elevated concentrations of metals
were assessed by the TCLP method in accordance with the requirements of O.Reg.558. The results are
Terraprobe
Page No. 6
AECOM
October 1, 2009
File No. 1-09-4138
presented on Page 6 of 27 of the Certificate of Analysis, Appendix C. None of the samples assessed was
characterized as hazardous waste on the basis of this testing.
The investigation did not include significant characterization of the quality of the underlying native soil.
Further investigation is required to determine potential impact to the underlying soil. However, it is noted that
fill materials will likely be found below the finished grade elevation of the site. It is likely that removal of
all the fill material, down to the non-impacted native soil, will be a costly exercise. It is expected that
impacted fill materials will remain on the site, and that a Risk Assessment will be required to demonstrate
that the site can be safely developed for the intended purpose.
For preliminary planning purposes, it should be assumed that a “clean soil” layer not less than 1.5 m thick
will have to be made at the surface of the site, and that a thicker replacement may be desirable in buried utility
corridors so that any future work on the utilities does not expose workers to the impacted soil.
3.3
Ground Water Quality
Samples of ground water were obtained from the monitoring wells installed in Boreholes D, H and 3. The
samples were analysed for metals and other inorganic parameters, petroleum hydrocarbons F1 to F4, volatile
organic compounds, PAH and PCB.
There were no significant exceedances of the Table 3 Standards for the parameters measured. It is noted that
the ground water characterization is preliminary and that further sampling must be conducted to provide
stabilized ground water chemistry.
Based on the current information, it appears that ground water quality will not be a significant constraint with
respect to the occupancy of the site. However, additional ground water quality characterization must be
conducted to determine potential requirements for disposal of ground water which may enter excavations
during construction, and/or for long-term drainage of ground water from the site through backfill or
subsurface utilities.
3.4
Summary
In summary, the results of the preliminary investigation indicate the following:
•
There is a large mound of fill found on the property. The fill appears to extend below the
elevation of the surrounding street grades at Leslie Street and Lakeshore Boulevard.
•
The fill consists of a mixture of common earth with significant amounts of building debris
and rubble.
Terraprobe
Page No. 7
AECOM
•
October 1, 2009
File No. 1-09-4138
The fill generally exceeds the Table 3 Standards for a range of parameters including various
heavy metals, PAH compounds, and hydrocarbons.
•
Testing conducted to date indicates the fill is a non-hazardous waste material.
•
The native soils underlying the fill consist of soft/loose organic silt. Competent soils and
bedrock are found at depths of approximately 15 m or more below the proposed finished site
grades.
•
Based on the limited testing conducted to date, there appears to be no significant impact to
the ground water quality at the site.
The site conditions will pose significant constraints and expense to site development. The following issues
must be addressed as part of site development:
•
The fill materials at the site must be removed from the property. The fill must be removed
as a waste material. Further characterization is required to assess the fill material. There is
a significant potential that at least portions of the fill material may be categorized as a
hazardous waste. This would likely require the material be stabilized before off-site disposal.
•
Fill material will remain at the site below the elevation of the proposed site grades. Complete
removal of the fill material is likely expensive and prohibitive. In lieu, consideration should
be given to conducting a Risk Assessment for the property. A Risk Management Measure
will be required to isolate the fill. Typically the Risk Management Measure will consist of
a cap of clean soil over the property. Underground utilities would also be buried within a
clean soil fill zone.
•
The consistency of the fill, and the soft, loose organic silt materials will pose geotechnical
constraints to site development. However, the presence of the fill mound has resulted in
considerable pre-loading of the fill and native soils. On this basis, the subgrade conditions
at the site will likely be suitable for pavement and rail systems, with some special
considerations. Buildings or other large or heavy structures will likely require support on
deep foundations carried down to the dense, native soils or bedrock.
A significant portion of the cost of development will be for the off-site removal and disposal of the fill
materials at the site. Additional studies are required to characterize the fill materials and determine the most
appropriate and cost-effective methods for off-site disposal.
Terraprobe
Page No. 8
AECOM
4.0
LIMITATIONS AND USE OF REPORT
4.1
Procedures
October 1, 2009
File No. 1-09-4138
This investigation has been carried out using investigation techniques and engineering analysis methods
consistent with those ordinarily exercised by Terraprobe and other engineering practitioners, working under
similar conditions and subject to the time, financial and physical constraints applicable to this project.
The drilling work and trenching were carried out by a drilling and an excavating contractor under the fulltime supervision of a Terraprobe technician. The borings were made by a continuous flight power auger
machine using solid and hollow stem augers as appropriate to secure samples. The supervising technician
logged the borings and test trenches and examined the samples as they were obtained. The samples obtained
were sealed in clean, air-tight containers and transferred to the Terraprobe laboratory where they were
reviewed for consistency of description by a geotechnical engineer. Ground water observations were made
in the boreholes as drilling proceeded. Water levels were also assessed in the monitoring wells installed as
part of these works.
The samples of the strata penetrated were obtained using the technique Split-Barrel Method, ASTM D1586.
The samples were taken at intervals. The conventional interval sampling procedure used for this investigation
does not recover continuous samples of soil at any borehole locations. Consequently, there is some
interpolation of the borehole layering between samples and indications of changes in stratigraphy, as shown
on the borehole logs, are approximate. A comprehensive sampling and testing program implemented in
accordance with the most stringent level of care may fail to detect certain conditions. Terraprobe has assumed,
for the purposes of providing design parameters and advice, that the conditions that exist between sampling
points are similar to those found at the sample locations.
It may not be possible to drill a sufficient number of boreholes or sample and report them in a way that would
provide all the subsurface information that could affect construction costs, techniques, equipment and
scheduling. Contractors bidding on or undertaking work on the project should be directed to draw their own
conclusions as to how the subsurface conditions may affect them, based on their own investigations and their
own interpretations of the factual investigation results, cognizant of the risks implicit in the subsurface
investigation activities.
Terraprobe
Page No. 9
APPENDIX A
TERRAPROBE LIMITED
APPENDIX B
TERRAPROBE LIMITED
APPENDIX C
TERRAPROBE LIMITED
APPENDIX D
TERRAPROBE LIMITED

Terraprobe

Transcription

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