CANADIAN SEABED RESEARCH LTD. WOLFE ISLAND CABLE …k7waterfront.org/files/WolfeIslandWindProject/...Wolfe_Island_rpt.pdf · WOLFE ISLAND CABLE ROUTE SURVEY Geophysical Survey Results

CANADIAN SEABED RESEARCH LTD.

WOLFE ISLAND CABLE ROUTE SURVEY

Geophysical Survey Results

DRAFT

Submitted to: CANADIAN RENEWABLE ENERGY CORPORATION

c/o Canadian Projects Limited #240, 523 Woodpark Blvd. SW

Calgary, Alberta T2W 4J3

Submitted by: Canadian Seabed Research Ltd.

341 Myra Road Porter's Lake, Nova Scotia

B3E 1G2 Telephone: (902) 827-4200

Email: [email protected]

CSR Author: Andrew Campbell CSR Project Number: 0610 Submission Date: June 2006

0610 WOLFE ISLAND CABLE ROUTE SURVEY Geophysical Survey Results

CANADIAN SEABED RESEARCH LTD, 2006

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TABLE OF CONTENTS TABLE OF CONTENTS..................................................................................................... i LIST OF FIGURES ............................................................................................................ ii LIST OF TABLES.............................................................................................................. ii LIST OF ENCLOSURES .................................................................................................. iii STATEMENT OF QUALITY........................................................................................... iii EXECUTIVE SUMMARY ............................................................................................... iv 1.0 INTRODUCTION .........................................................................................................1 2.0 SURVEY OPERATIONS..............................................................................................1

2.1 Survey Equipment..................................................................................................... 1 2.1.1 Integrated Navigation System............................................................................ 1 2.1.2 Knudsen 320M Dual Frequency Echosounder .................................................. 1 2.1.3 Klein 100kHz Sidescan Sonar ........................................................................... 3 2.1.4 Klein 3.5 kHz Sub-Bottom Profiler ................................................................... 3 2.1.5 Marine Magnetics Seaspy Magnetometer.......................................................... 4 2.1.6 Sound Velocity Profiler ..................................................................................... 4

2.2 Ground Truth Equipment.......................................................................................... 5 2.2.1 CSR Hand Dredge.............................................................................................. 5 2.2.2 Delta Vision HD Marine Video Splashcam....................................................... 5

3.0 RESULTS ......................................................................................................................6 3.1 Bathymetry................................................................................................................ 6 3.2 Surficial Geology...................................................................................................... 6 3.3 Shallow Sub-Bottom Geology .................................................................................. 9 3.4 Lake Bed Features................................................................................................... 21 3.5 Magnetometer data.................................................................................................. 32

4.0 CURRENT METER AND WATER LEVEL DATA..................................................35 4.1 Current Meter Data ................................................................................................. 35 4.2 Lake Water Levels .................................................................................................. 36

5.0 ROUTE CONSITERATIONS.....................................................................................44 6.0 SUMMARY.................................................................................................................45 7.0 RECOMMENDATIONS.............................................................................................47 8.0 REFERENCES ............................................................................................................48



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LIST OF FIGURES Figure 1.01 – Location Map.................................................................................................2 Figure 3.01 – Video still frame images of the surficial sediments present within Unit A...7 Figure 3.02 – Sidescan sonar image of the dredge spoils present on the seabed within

Unit A................................................................................................................8 Figure 3.03 – Video still frame image of the shellfish beds present on the seabed within

Unit A..............................................................................................................10 Figure 3.04 – Sidescan sonar images of scours present on the lake floor within Unit A. .11 Figure 3.05 – Sidescan sonar image of the surficial sedimentary unit B...........................12 Figure 3.06 – Sidescan sonar image of the surficial sedimentary unit C...........................13 Figure 3.07 – Video still frame image showing boulders present within unit C. ..............14 Figure 3.08 – Sidescan sonar and video still frame images of bedrock present at the

Kingston shore. ...............................................................................................15 Figure 3.09 – Sidescan sonar and video still frame images of bedrock present at the shoal

near Wolfe Island. ...........................................................................................16 Figure 3.10 – Digital photograph of large boulders resting on top of bedrock at the shoal

near Wolfe Island. ...........................................................................................17 Figure 3.11 – Sub-bottom profile image of R1 and where it is masked by gas.................19 Figure 3.12 – Sub-bottom profile image of R2..................................................................20 Figure 3.13 – Sub-bottom profile image of R3..................................................................23 Figure 3.14 – Sub-bottom profile image of bedrock at the shoal near Wolfe Island.........24 Figure 3.15 – Sidescan sonar image of a shallow depression present on the lake floor. ...27 Figure 3.16 – Sidescan sonar image of the elevated mound within the area of dredge

spoils. ..............................................................................................................28 Figure 3.17 – Sidescan sonar image of possible boulders present on the lake floor. ........29 Figure 3.18 – Sidescan sonar image of the KPH wreck. ...................................................30 Figure 3.19 – Sidescan sonar and sub-bottom profile images of the intake/outflow pipe

present at the Kingston shore. .........................................................................31 Figure 3.20 – Raw magnetic profile displaying background magnetic flux......................33 Figure 3.21 – Raw magnetic flux profile of a magnetic anomaly .....................................34 Figure 4.01 – Lake Ontario current direction in 2004 .......................................................37 Figure 4.02 – Lake Ontario current direction in 2005 .......................................................38 Figure 4.03 – Lake Ontario current direction in 2006 .......................................................39 Figure 4.04 – Lake Ontario current speed in 2004 ............................................................40 Figure 4.05 – Lake Ontario current speed in 2005 ............................................................41 Figure 4.06 – Lake Ontario current speed in 2006 ............................................................42 Figure 4.07 – Average water levels from 1918 to 2005 ....................................................43

LIST OF TABLES Table 3.1 – Identified Lake Bed Features ..........................................................................22 Table 3.2 – Table of Magnetic Anomalies.........................................................................32 Table 4.1 – Monthly Current Speed (m/sec)......................................................................35



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LIST OF ENCLOSURES Enclosure 1 – Alternative Cable Route & Bathymetry Chart Enclosure 2 – Surficial Geology and Seabed Features Enclosure 3 – R1 & R2 Isopach Map Enclosure 4 – Depth of Unconsolidated Sediments Enclosure 5 – Centerline and Wing-line Profiles

STATEMENT OF QUALITY Canadian Seabed Research Ltd. warrants that its service with respect to this study was performed with a degree of skill and care equal to or greater than that ordinarily exercised under similar conditions by reputable members of our profession practising in the same or similar locality. No other warranty, expressed or implied, is made or intended.



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EXECUTIVE SUMMARY Canadian Seabed Research (CSR) was contracted by the Canadian Renewable Energy Corporation to perform a geophysical survey for a proposed sub-marine cable between Wolfe Island and Kingston, Ontario. Survey operations were conducted between April 10th and 16th, 2006 onboard the CSR survey vessel “Sea Star”. The bathymetry of the survey corridor ranges from 23m to as shallow as 1.0m. Water depths ranging from 16m to as deep as 23m are present across the harbor channel before it shallows to 5m and 1.5m between Simcoe Island, Garden Island, and extending to the Wolfe Island shore. A bathymetric shoal is present 150m lakeward of Wolfe Island, and contains water depths of 1.5m. The surficial sediments within the survey corridor where broken into five main units for the purpose of this report. These units are based on their signatures in the geophysical records (sidescan sonar, sub-bottom profiler and echo sounder) and ground truthed by surficial grab samples and underwater video. The units consist of soft, unconsolidated, fine sediments with varying amounts of shell fragments and coarse materials as well as bedrock. The thickness of the unconsolidated sediments varies across the survey corridor. The sub-bottom geology consists primarily of four visible reflectors, as well as multiple areas of shallow gas. Unconsolidated sediments are visible as thick as 23m in the northwest survey area, less than 2m in some areas where the water depths are shallow, and not present in the areas where bedrock is visible at the lake bed. A number of features have been identified on the lake floor within the survey area. These features include dredge spoils, shellfish beds, scours, shallow depressions, boulders, an outflow/intake pipe, and the wreck of the KPH. Based upon the analysis of all the geophysical data available from the survey area, the underlying geology may cause some challenges to the installation of the power cable. The deep water sections of the survey area are relatively free of engineering constraints, and thick unconsolidated sediments should provide adequate protection if the cable is to be buried. This portion of the route is however not without lake bed features such as dredge spoils, shellfish beds, and shallow sub-bottom gas. In the shallow water sections of the survey, the unconsolidated sediments thin and are not present in some places where bedrock is at the lake bed. Lake bed features in the shallow water portions of the proposed cable route include boulders, shallow depression features, and areas of shallow sub-bottom gas. Due to the presence of a bedrock shoal, 3 alternative cable routes were proposed by CSR to by-pass the shoal, and to maximize the amount of unconsolidated sediment in which to bury the power cable. Alternative route 1 was selected by the client to be used as the cable route, which alters the route 380m southwest of the original centerline.



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Where geophysical data is available, a 20m wide corridor (centre line and 2 wing lines) has been selected along the length of the cable route where engineering constraints have not been identified. There is no geophysical data available in the areas where the cable route is altered outside of the original 200m survey corridor.

0610 WOLFE ISALND CABLE ROUTE SURVEY Geophysical Survey Results


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1.0 INTRODUCTION Canadian Seabed Research (CSR) was contracted by the Canadian Renewable Energy Corporation to perform a geophysical survey for a proposed sub-marine cable between Wolfe Island and Kingston, Ontario (figure 1.1). During survey operations, approximately 169 km of geophysical data was collected within the 200m survey corridor of the proposed cable route.

2.0 SURVEY OPERATIONS Survey operations were conducted between April 10th and 16th, 2006 onboard the CSR survey vessel “Sea Star”. The “Sea Star” is a 22’ fiberglass-hulled, Rosborough designed vessel. The survey equipment installed on the “Sea Star” included a differential GPS positioning system, dual frequency Knudsen echo sounder, Klein 100kHz sidescan sonar, Klein 3.5 kHz sub-bottom profiler, Marine Magnetics Seaspy magnetometer and Applied Microsystems Ltd. SVPLUS sound velocimeter.

2.1 Survey Equipment 2.1.1 Integrated Navigation System A real time differential GPS system was utilised for this survey. The integrated navigation system consisted of a CSI GBX PRO differential GPS system to receive satellite positional data and differential corrections throughout the survey. Differential corrections were received from a Canadian Coast Guard beacon and used to correct the data in real time. Data was logged directly into the Hypack survey navigation workstation and was used for real time navigation of the survey vessel. The system is capable of achieving ± 1 metre accuracy with a 95% confidence level. All survey data were collected in UTM coordinates (Zones 18) based on WGS84 ellipsoid and datum.

2.1.2 Knudsen 320M Dual Frequency Echosounder The echo sounder used during survey operations was the Knudsen 320M dual frequency echosounder. Using either the high or low frequency channel, or both simultaneously, the Knudsen 320M Dual Frequency Echosounder produces a high resolution record accurately depicting bottom profiles and sediment layers with 32 shades of grey. The thermal printer uses easily loaded 21.6cm (8.5") plastic film for permanent, high-quality records. The annotated depth grid is printed with reverse shading for clarity. Digitized water depth is shown on two large 4-digit LCD displays, visible indirect sunlight and back lit for night operation. Serial RS232 depth data is continuously available in NMEA format as well as user-defined string formats, and in operator-selectable time and position tagged formats. An LCD menu display with simple 2-button control provides access to

Canadian Seabed Research Ltd.

Figure 1.1 - Survey location map

N

GR

ID NORTH

Wolfe Island

Amherst

Island

Simcoe

Island

Grenadier

Island

Ontario

New York

State

Kingston

Survey Area

Lake

Ontario



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parameters such as sound velocity, draft, TX blanking, serial port assignment, time and date setting, and many more, as well as a variety of self-test, communication and configuration features. All settings are retained in non-volatile memory and recalled on power-up. Three RS232 ports support communication with personal computers, NMEA in put and out put devices, GPS receivers, sound velocity sensors, heave sensors, remote depth displays and survey data loggers.

2.1.3 Klein 100kHz Sidescan Sonar Sidescan sonar data was obtained using a Klein 595 tow fish. The sidescan system was operated at 100 kHz, at a 75 meter range setting. The sidescan system offers real-time complete slant range and speed correction to preserve the dimensions and orientations of all seafloor features such as shipwrecks, debris, sediment bedforms, etc. Fix marks generated by the Hypack navigation software was annotated on the records at 50 meter intervals. Fix numbers were also annotated manually at each fix mark and the data was recorded digitally by the Coda acquisition system. Gain settings were manually adjusted to account for changing bottom types. The Sidescan sonar tow fish was deployed from the port side of the aft deck of the survey vessel “Sea Star”. The cable length deployed was less than 5 meters depending on water depth and was recorded on the survey line log each time adjustments were made. The sidescan sonar tow fish was deployed, retrieved, and adjusted by hand. The Sidescan was interfaced with the CODA Octopus 160 unit and the CODA DA 100 digital acquisition system to digitally record the data. Coda Digital Acquisition System A Coda DA 50 digital acquisition system and CODA Octopus 160 sonar interface unit were used to interface the Klein tow fish and navigation system while surveying to collect geo-referenced sidescan sonar data in digital form. The stored data can be replayed by the Coda system in order to enhance the data or create sidescan mosaics. Processed or enhanced data can then be re-saved in Coda file format or converted to XTF or SEGY file format if required. Mosaics can be exported in geo-referenced TIFF file format. The small and rugged black box style setup of the Octopus 160 interface unit was also ideal for the limited space available in the small boat configuration on “Sea Star”.

2.1.4 Klein 3.5 kHz Sub-Bottom Profiler Sub-bottom geology data was obtained using the Klein 3.5 kHz Sub-bottom profiler. This profiler uses a 3.5 kHz frequency to obtain high resolution profiles in soft sediments.



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The profiler transducer was mounted inside the vessel hull to reduce the ringing and noise typical within the water column in shallow water. This system has the ability to resolve buried pipelines, and other anthropogenic material buried beneath the seafloor. The sub-bottom profiler was interfaced with the Coda acquisition system where the data was displayed and recorded digitally, as well as printed to hard copy using an EPC printer.

2.1.5 Marine Magnetics Seaspy Magnetometer A SeaSPY magnetometer produced by Marine Magnetics was used to discern anthropogenic ferrous-based materials on or below the seafloor. The SeaSPY is a proton magnetometer utilizing the Overhauser effect. This effect allows the sensor to be polarized with a low power, high frequency, magnetic field, instead of a high power DC magnetic field. The advantages of this unit are that it does not produce a heading error, have a dead zone or display a temperature drift like many of the Cesium models. The SeaSPY operates at a resolution of 0.001nT, with a sensitivity of 0.015nT and an absolute accuracy of 0.2nT. All acquired data was logged directly to the integrated navigation workstation for post processing and positioning of anomalies.

2.1.6 Sound Velocity Profiler Sound velocity of the water column was obtained using the Applied Microsystems Ltd. SVPLUS sound velocimeter. The Applied Microsystems Ltd. SVPLUS sound velocimeter is a multi-parameter, self-contained, intelligent instrument, designed for the measurement of sound velocity, temperature, and pressure. The aluminum pressure case and sensor protection cage are hard-anodized for corrosion resistance and durability. The pressure sensor consists of a Keller stainless steel pressure transducer operational within a range of 0 to 500 dBar to an accuracy of 0.15% of Full Scale. Temperature is registered through a pressure protected precision aged thermistor operational between –2oC to 32oC at an accuracy of ±0.05oC. Sound velocity is acquired through a 1 Megahertz piezoelectric transducer within a range of 1400-1500 m/s at an accuracy of <0.06 m/s. The SVPLUS has the options of logging data continuously, by depth increments, by time intervals, by sound velocity increments, or logging individual scans. Programmable sampling rates vary from 10scans/second to one every 24 hours. Time is recorded through a real time clock accurate to ±1 minute/month at 25oC. A 128k battery backed-up RAM can record 6,400 scans of date, time, pressure, temperature, sound velocity, and battery power. Data is transferable to an IBM compatible computer through a standard ASCII RS-232 in either unprocessed integers, or computed engineering values for immediate data processing and sound velocity applications.



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2.2 Ground Truth Equipment

2.2.1 CSR Hand Dredge Sediment samples were collected using the CSR hand dredge. The light weight dredge was designed to be deployed and recovered by hand, and collects the sediment sample while being pulled across the lake floor. Sediment samples were helpful with the interpretation of surficial sediment grain size, consistency and the percentages of each sediment type and shell fragments present within the surficial sedimentary unit. 2.2.2 Delta Vision HD Marine Video Splashcam The Delta Vision, HD Marine Video Splashcam was used during the survey to obtain digitally recorded underwater video and still images of the lakebed. The Splashcam is a 3.6mm, black and white camera with a resolution of 400 TV lines. Its light weight allows it to be deployed and recovered by hand. The video footage was helpful with the interpretation of surficial sediment textures, as well a confirming the presence of bedrock, boulders, and lake floor organisms such a shellfish beds.



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3.0 RESULTS The site geology presented in this section is based on the interpretation of the geophysical data sets collected during survey operations.

3.1 Bathymetry The bathymetry of the survey corridor ranges from 23m to as shallow as 1.0m. Along the Kingston shore, water depths of 1m to 7m extend lake ward approximately 30 metres before the lake floor quickly drops to water depths of 18 metres. Water depths ranging from 16m to as deep as 23m are present across the harbor channel for 450 metres, where it begins to quickly shallow. This shallow area is located between Simcoe and Garden Island, and extends to the Wolfe Island shore. The bathymetry in the shallow area ranges from 5m, to less than 1.5m in a bathymetric shoal. This bathymetric shoal is located approximately 150 metres lakeward of Wolfe Island. Enclosure 1 displays the bathymetric data across the survey corridor. Enclosure 1 also includes additional sounding data acquired from CHS (Canadian Hydrographic Service) Field Sheets 8078 (1981{sounding in metres}) and 3664 (1970 {soundings in feet}). The additional soundings are located outside of the 200 metre survey corridor, in the shallow area between Simcoe and Garden Islands. They are included in order to propose possible alternative cable routes around the bathymetric shoal. The soundings, (spaced approximately 50 to 100 metres apart on both field sheets), were incorporated into the CSR collected bathymetry data. The alternative routes were determined using bathymetry data only in order to achieve the deepest possible water depths.

3.2 Surficial Geology The surficial sediments within the survey corridor are broken into five main units. These units are classified based on their signature on geophysical records (sidescan sonar, sub-bottom profiler and echo sounder) and were ground truthed by surficial grab samples and underwater video. Enclosure 2 displays the distribution of the surficial geology across the entire survey corridor. Unit-A Unit A is the surficial unit extending from the near shore of the main land, approximately 400 metres across the channel and into the shallow portions of the survey corridor. This unit is comprised of very fine clay sediments with varying amounts of shell fragments and shellfish beds (figure 3.1). Grab samples collected within this unit contained very fine, saturated brown clay with some shell fragments and intact, white coloured clams.


Figure 3.1 - Video still frame images of the surficial sediments present within Unit A. Pictures A and B show fine clay sediments characteristic of the unit as well as shell beds. Picture C shows featureless, very fine clay. Picture D shows are area within the unit with abundant shell fragments.

A B

DC


Figure 3.2 - Sidescan sonar image of dredge spoils present within Unit A

50m

50m

Dredge Spoils



9

Unit A also contains an area were dredge spoils and shellfish beds are present, characterized by the dark, circular features in the sidescan imagery, (figure 3.2). It appears that the shellfish beds correlate with the circular shaped dredge spoils, indicating that the shell fish habitat formed as a result of the dumped dredge spoils. Figure 3.3 presents still frame images from video footage collected of the shellfish beds within Unit A. Drag marks from fishing and/or other activity can also be seen within this unit (figure 3.4). Unit-B Unit B is present at the seafloor in the shallow area of the survey corridor, on the northwest side of the shoal. This unit is interpreted to be fine sand sediments with abundant shell fragments. Occasional gravel sized clasts are randomly distributed throughout the unit. Figure 3.5 displays sidescan imagery of Unit B. Unit-C Unit C is present at the seafloor between the bathymetric shoal and Wolfe Island. This unit is mostly comprised of sandy silt and an abundance of shell fragments. Gravel and cobble sized clasts are common within the unit, as well as the occasional boulder. Figure 3.6 is a sidescan image displaying Unit C, and figure 3.7 displays video still frame images of the sediments present in unit C, including boulders. Unit-D Unit D is the local bedrock surface, and is found at the Kingston shore and at the bathymetric shoal near Wolfe Island. Erosion features such as fractures and glacial striations are visible in the video footage and sidescan sonar data collected over the unit. Cobbles and boulders are also visible resting on the top of the bedrock surface. Figure 3.8 and Figure 3.9 display sidescan sonar and video still frame images of the bedrock surface at the Kingston shore and the bathymetric shoal respectively. Figure 3.10 shows digital photographs taken from the back deck of the survey vessel at the shoal and displays boulders resting on top of the bedrock surface. Unit-E Located on the Wolfe Island side of the survey area, this acoustically opaque unit appears to correlate with the adjacent onshore geology, and is overlain by a marine sediment sequence offshore. Cobble to boulder sized clasts and erosion debris can be found throughout this unit.

3.3 Shallow Sub-Bottom Geology The sub-bottom profiler used during the survey is able to obtain high resolution profiles in soft unconsolidated sediments; however, the 3.5 kHz system is unable to penetrate through sediments that contain coarse material such as till. It is possible that deeper sedimentary units are present in the survey area beneath the deepest reflectors outlined in this report.


Figure 3.3 - Video still frame images of the shellfish beds present within Unit A


Figure 3.4 - Sidescan sonar images of scour marks visible on the lake floor within Unit A.

Scours

Dredge Spoils &Shellfish Beds

Scours

Fine Sediments

50m

10m

Water Column

Lake Floor

Scours

Scours

50m

10mWater

Column

Lake Floor

Fine Sediments


Figure 3.5 - Sidescan sonar image of surficial sedimentary Unit B

Unit B

50m

10m

Unit A

Watercolumn

Lake Floor


Figure 3.6 - Sidescan sonar image of surficial sedimentary Unit C

Unit C50m

10m

Watercolumn

Lake Floor

Unit C


Figure 3.7 - Video still frame images of the surficial sediments present within Unit C. The images show coarse sediment clasts and abundant shell fragments present within the unit. The images also show boulders resting on the seafloor.


50m

50m

Figure 3.8 - Sidescan sonar and video still frame images of bedrock where it is present at the Kingston Shore.

Bedrock

Boulder

Bedrock

Eroded bedrock surface


Figure 3.9 - Sidescan sonar and video still frame images of bedrock where it is present at the bathymetric shoal near Wolfe Island.

Boulders

Bedrock

Bedrock

Bedrock

50m

20m


Figure 3.10 - Digital pictures of boulders resting on the top of bedrock at the bathymetric shoal. The pictures were taken from the back deck of the survey vessel.

Boulders

Boulder



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Below the surficial sediments described above, the shallow sub-bottom geology is characterized by four primary reflectors as well as multiple areas of shallow gas. The northwest side of the survey area consists of a thick sedimentary sequence which includes the R1 reflector, underlain by a discontinuous, deeper reflector (R3). On the Wolfe Island side of the 10m contour, the sub-bottom sediments become shallow. Two sub-bottom reflectors are visible in this area, consisting of a shallow surficial sedimentary sequence, underlain by coarser sedimentary units R2, and R3. Bedrock is visible on the seafloor at the bathymetric shoal near Wolfe Island. Shallow gas is also present, visible in multiple areas across the survey corridor. Enclosure 3 is an isopach map showing the depths to the R1 and R2 reflectors, as well as the location and depths where gas is visible. Enclosure 4 displays the depth to the deepest sub-bottom reflector visible in the sup-bottom profiler data, which represents the base of the unconsolidated surficial sediments. The uppermost sedimentary unit, extending below the surficial sediments, is nearly acoustically transparent and ranges in thickness from 5m to as shallow as 1m. This unit is underlain by R1 in the northern half of the survey area, and R2 in the southern, shallow portions of the survey. The sidescan data and video footage show that the unit varies in quantities of coarse material such as gravel and cobble size clasts, as well as shell fragments, however, the unit’s transparent nature in the sub-bottom data indicates that it is composed of soft, unconsolidated sediment. R1 R1 is the primary reflector visible throughout the northwestern side of the survey area. The R1 reflector is continuous and relatively flat lying within thick, acoustically near transparent sediments. The reflector is located at an average depth of 3.5m below the lakebed (figure 3.11). The depth to which the sub-bottom profiler is able to penetrate beneath R1 suggests that it is the upper surface of a soft sediment sequence similar to that of the surficial geology, continuing to depths ranging from 10m to 25m below lakebed. The R1 reflector is periodically masked by shallow gas present in the area. R2 R2 is a strong to moderate reflector visible in the southeast survey area. R2 is the surface of a near opaque unit of variable thickness (figure 3.12). It is possible that R2 represents the top of a medium to coarse sedimentary unit and is found at depths ranging from 4m to 1m below lakebed. R3 R3 is a discontinuous, weak reflector representing the deepest resolvable reflector in the sub-bottom data set. The weak appearance of this reflector, and its inconsistent visibility from one survey line to the next made it difficult to map. It is thought that the areas where the reflector is not visible is due to coarse material in the upper sediments that the sub-bottom acoustic signal is unable to penetrate or that it is closely underlying


Figure 3.11 - Sub-bottom profiler image displaying sub-bottom reflectors near the Kingston shore. Bedrock is present on the lake bed in the right of the image before it trends beneath the marine sediments. R1 is the flat lying reflector visible across most of the image except in the middle, where it is masked by gas. The deeper R3 reflector is also visible in the left of the image.

100m

5m

Area of acoustic masking caused by the presence of gas

Lakefloor

R3

R1Gas

Multiple Reflections

Water Column

R1

Bedrock


Figure 3.12 - Sub-bottom profiler image displaying the R2 reflector.

100m

10m LakefloorR2


Water Column



21

R2, making it difficult to differentiate between the two. It is thought that R3 is the upper surface of course till sediments or bedrock, however without ground truth data, its lithology can not be determined. Figure 3.11 displays the R3 reflector where it is visible near the Kingston shore, and figure 3.13 displays R3 where it is visible in the shallow areas near Wolfe Island. No coherent sub-bottom reflectors are visible beneath R3. Bedrock Bedrock is characterized by a strong continuous reflector, with no coherent reflectors visible beneath it. It is visible in the sub-bottom data over short distances, trending at steep angles away from the lake bed, beneath the marine sediments and out of range of the sub-bottom profiler. Figure 3.11 displays the bedrock surface at the Kingston shore as it quickly drops below the range of the sub-bottom profiler. Figure 3.14 displays the bedrock surface where it is visible at the bathymetric shoal, near Wolfe Island. The bedrock surface was only mapped in areas where ground truthing confirmed its presence. Gas Shallow gas is visible in multiple areas within the survey corridor. Gas within the sediments prevents the penetration of the acoustic energy from the sub-bottom profiler, masking the underlying geologic reflectors, (Figure 3.11). The top of the gas reflector is flat lying, and visible at depths averaging 2.5m below the lake bed. The origin of the shallow gas in the survey area can not be determined from the data collected from this survey. The gas could be originating from shallow, decomposed organic material or from deep underlying formations. It is possible that the gas originated from the decomposition of vegetation that may have grown during low lake levels, and was then buried as the lake level rose.

3.4 Lake Bed Features Several lakebed features have been identified in the geophysical data. These features are discussed below. The features that are potential engineering concerns are included in Table 3.1, and in Enclosure 2. Dredge Spoils and Shellfish Beds Two areas of dark, circular features typical of dumped dredge spoils are present in the sidescan data, (figure 3.2). The dredge spoils are located between 1100m and 1800m from the Kingston shoreline, are relatively flat lying and range in size from 10m to 30m in diameter. Shellfish bed accumulations are also present within the same areas, seemingly associated with the dredge spoils. It appears that the thick clusters of shellfish beds correlate with the circular shaped dredge spoils, indicating that the shell fish habitat formed as a result of the dumped dredge spoils (figure 3.3). Scour Marks Linear areas of disturbed sediment on the lake bottom are visible in the sidescan data, (figure 3.4). These linear scours occur in the same areas where the dredge spoils and

Table 3.1 - Identifyed Lake Bed Features

Reference Number Easting Northing

Detection Instument

Water depth (m)

Length (m)

Width (m)

Height (m)

Resting Position description

1 376984 4896311 sidescan sonar 11 7 1 0 seabed linear target - possible boulder2 376995 4896267 sidescan sonar 11 9 1 1 seabed linear target - possible boulder3 376659 4896046 sss/sbp 18 12 2 seabed Intake/Outflow pipe and trench area4 377055 4895830 sidescan sonar 23 41 7 2 seabed KPH-wreck 5 377875 4895459 sidescan sonar 19 18 5 2 seabed large mound within dredge spoil area6 378071 4895628 sss/sbp 18 25 10 2 seabed large mound within dredge spoil area7 379370 4894889 sidescan sonar 16 3 1 seabed small dark targ-no shadow 8 379441 4894820 sidescan sonar 12 3 seabed shallow, circular depression9 379484 4894838 sidescan sonar 15 2 seabed shallow, circular depression10 379488 4894869 sidescan sonar 13 1 seabed shallow, circular depression11 379609 4894844 sidescan sonar 10 1 seabed shallow, circular depression12 379998 4894595 sidescan sonar 7 3 2 0 seabed round target - possible boulder13 380517 4894269 sidescan sonar 5 2 1 0 seabed round target - possible boulder14 381095 4893983 sidescan sonar 5 3 2 0 seabed low lying boulder,no shadow15 381168 4893998 sidescan sonar 4 3 2 0 seabed low lying boulder,no shadow


Figure 3.13 - Sub-bottom profiler image displaying the R3 reflector.

100m

10m

Lakefloor

R2


Water Column

R3


Figure 3.14 - Sub-bottom profiler image displaying bedrock at the bathymetric shoal near Wolfe Island. The image also shows the R2 and R3 reflectors.

50m

10mLakefloor

Bedrock Reflector


Water Column

R3

R2

R2



25

shellfish bed colonies are found. It is possible that the scours are a result of fishing activity or the dragging of anchors. Circular Depression Features A number of shallow, circular depression features have been observed in the sidescan data, (figure 3.15). The origin of these features can not be determined from the data collected from this survey, however previous research conducted by the Geological Survey of Canada have identified similar features as pockmarks, and have associated them with the venting of shallow gas (Josenhans et al, 1990, Josenhans and Zevenhuizen, 1993). The features found within this survey range in diameter from 1 to 3.5m and are located where the bathymetry quickly shallows from the deep channel into the shoal area between Simcoe and Garden Islands. The identified depression features are listed in Table 3.1, and are included in Enclosure 2. Raised Relief Features A number of targets, raised above the seafloor are visible within the sidescan data. The dredge spoils identified within the survey area are one such feature. The majority of the spoils are relatively flat lying; however in places, possibly where multiple spoil dumps were made over top of one another, larger mounds have been created. Figure 3.16 displays two such mounds that extend over 1 metre above the seabed. Boulders are also present in the survey area, noted on the sidescan data as round objects resting on the lake bed. They are most common near the shoreline areas of the survey, as well at the shoal, lying on top of bedrock, (figure 3.17). The sidescan targets interpreted to be boulders are listed in Table 3.1 and included in Enclosure 2. KPH Wreck The wreck of an unknown steamer, nicknamed the “Kingston Psychiatric Hospital” (KPH) is located approximately 180m southwest of the proposed cable route centerline, 80m outside the survey corridor. Found in 20m of water, the wreck is 41.2m long, by 7.5m wide, resting upright, extending 2m above the lake floor. The KPH wreck is an actively used recreational dive site regarded as a diving gem (Online at Northern Tech Diver). Figure 3.18 is a sidescan sonar image displaying the KPH wreck resting on the lake floor. The position of the KPH is included in Table 3.1 and Enclosure 2. Intake/Outflow Pipe An intake/outflow pipe is located at the Kingston shoreline, approximately 170m southwest of the proposed cable route centerline, 70 m outside the survey corridor. The intake/outflow pipe extends in a south-southeastern direction for approximately 270 m from the shoreline. Based on the geophysical data collected during the survey, the pipe trench area is 12m wide and 1.5m above the lake bed. Figure 3.19 shows the intake/outflow pipe in sidescan and sub-bottom data. It is also included in Table 3.1 and Enclosure 2.


Figure 3.15 - Sidescan sonar images of shallow depression features identified in the survey area.

Depression Feature

Depression Feature

Depression Features


Figure 3.16 - Sidescan sonar images of elevated mounds of dredge spoils.

Elevated Dredge Spoil

Acoustic Shadow

50m

10m

Elevated Dredge Spoil

Acoustic Shadow

50m

10m


Figure 3.17 - Sidescan sonar images of possible boulders identified in the survey area.

Possible Boulder

PossibleBoulders


Figure 3.18 - Sidescan sonar and sub-bottom profile images of the KPH wreck. The Sidescan sonar image shows the wreck resting upright on the lakefloor. The Sub-bottom profile image shows the top of the wreck approximately 2m above the lakefloor.

KPH Wreck

KPH Wreck50m

10m

LakeFloor

50m

5m

LakeFloor


Figure 3.19 - Sidescan sonar and sub-bottom profile images of the intake/outflow pipe present at the Kingston shore.

Intake/Outflowpipe

50m

50m

Intake/OutflowpipeLake Bed

50m

5m



32

3.5 Magnetometer data Magnetometer data was collected inside the survey corridor to record the background magnetic flux of the area, as well as to identify any ferrous targets that may pose a concern to the cable. An example of a raw, uncorrected magnetic profile of the background magnetic flux of the area is presented in figure 3.20. CHS has identified the Kingston area to be one of erratic magnetic readings, and has labeled the region as a magnetic anomaly on the Hydrographic Navigation Chart 2017. This magnetic anomaly accounts for the large variations in magnetic flux found in the magnetometer data collected across the survey area, however, two anomalous values appearing as spikes in the data have also been identified. An example of such a magnetic anomaly is presented in figure 3.21. The position, magnitude, type of anomaly and an identification number for each anomaly is listed in Table 3.2. There were no visible targets in the sidescan sonar data that correspond to the magnetic anomalies, and the CHS navigational chart does not indicate the presences of any know sub-marine cables in the area.

Table 3.2 – Table of Magnetic Anomalies

ID # Easting Northing Magnitude

(nT) Anomaly

Type Observations on

Sidescan 1 381771 4893621 170 monopole no visible target 2 381694 4893530 240 monopole no visible target

Figure 3.20 - Raw magnetic flux profile along survey line 21. The profile displays the variable background magnetic flux in the Kingston area.

0 2000 4000 6000Distance Along Line (metres)

54400

54800

55200

55600

Mag

netic

Flu

x (n

anoT

esla

s)

Figure 3.21 - Raw magnetic flux profile example of a monopole magnetic anomaly. The profile is of magnetic anomaly number 1, which has a magnitude of 170nT

5920 5960 6000Distance Along Line (metres)

54440

54480

54520

54560

54600

Mag

netic

Flu

x (n

anoT

esla

s)



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4.0 CURRENT METER AND WATER LEVEL DATA The following section discusses the current metre and water level data in Lake Ontario.

4.1 Current Meter Data Water flow in Lake Ontario on the whole is mainly due to the Niagara River, and flows northeastward to the St. Lawrence River. Water currents are generally weak (Canadian Ice Service, 2004). The current meter data was provided by NOAA Great Lakes Environmental Research Laboratory (NOAA online, 2006). The data was generated from computerized models (Great lakes Coastal Forecast System) that can simulate and predict the three-dimensional structure of currents, temperatures, water level fluctuations, wind waves, and sediments in the great lakes. The project integrates these models with the required observational data systems into a real-time coastal prediction system. The results of that project are useful to all users of the Great Lakes coastal waters who require real-time information and forecasts of temperatures, currents, water levels, and waves. Figures 4.1 through 4.3 display the current direction for 2004, 2005 and the beginning of 2006. In 2004, the dominant direction is 80-105º, in 2005 it is 80-110º, and for January through April 2006, it is 85-95º. Figures 4.4 through 4.6 illustrate monthly current speed for 2004, 2005, and early 2006. Table 3.3 presents monthly maximum, minimum and average speed. The maximum speeds (about 0.5 m/sec) occur in December 2004 and January 2005. The average current speed for 2004, 2005 and 2006 is 0.119.

Table 4.1 – Monthly Current Speed (m/sec)

Month Month Average Minimum Maximum

Jan 1 0.36 -0.39 0.96 Feb 2 0.39 -0.42 1.07 Mar 3 0.47 -0.26 1.17 Apr 4 0.68 -0.17 1.45 May 5 0.81 -0.09 1.53 Jun 6 0.85 -0.01 1.56 Jul 7 0.79 -0.06 1.46 Aug 8 0.68 -0.2 1.38 Sept 9 0.54 -0.29 1.21 Oct 10 0.41 -0.38 1.02 Nov 11 0.34 -0.45 0.98 Dec 12 0.32 -0.46 1



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4.2 Lake Water Levels Water levels in the Great Lakes are dependant on a number of factors. Natural factors include storage capacity, inflow and outflow, run-off from the drainage basin, precipitation and evaporation. Anthropogenic factors include diversions into or out of the basin, consumption of water, dredging of outlet channels and the regulation of outflows (CHS, 2005). Water level data was supplied by MEDS. Figure 3.31 displays the average first-of-the-month water levels for Lake Ontario, along with the minimum and maximum values between 1918 and 2005. The water levels are displayed as values relative to the International Great lakes Datum of 1985. Lake Ontario has a chart datum of 74.2 and is the lowest of the great Lakes. The average water levels are highest in May and June, and lowest in the winter months: January, February, November and December. The highest the water level has been since 1918 is 1.56 m above chart datum (June), and the lowest is 0.46 m below chart datum (December) (MEDS).

0

45

90

135

180

225

270

315

0 100 200 300

Figure 4.1 - Rose Diagram displaying current direction in Lake Ontario in 2004. Dominant current directions are approximately East and West.


0

45

90

135

180

225

270

315


0

45

90

135

180

225

270

315

0 40 80 120

0 100 200 300 400Julian Day

0

0.2

0.4

0.6

Cur

rent

Spe

ed (m

/sec

)

Figure 4.4 - Graph displaying current speed (m/sec) for Lake Ontario in 2004.

0 100 200 300 400Julian Day

0

0.1

0.2

0.3

0.4

0.5

Cur

rent

Spe

ed (m

/sec

)


0 20 40 60 80 100 120

0

0.2

0.4

0.6

0.8


Fig 4.7 - Graph displaying average water level for the first of the month. Average, Maximum and Minimum values are displayed, calculated using first of the month values for each month 1918 through 2005.

-1

0

1

2

-0.5

0.5

1.5

Wat

er L

evel

rela

tive

to IG

DL

1985

Graph 4Average Water LevelMinimum Water LevelMaximum Water Level

Beginning of Month Water Levels

Jan

Feb Mar Apr May Jun Jul

Aug Sep Oct Nov Dec



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5.0 ROUTE CONSITERATIONS Based upon the analysis of all the geophysical data available from the survey area, the underlying geology may cause some challenges to the installation of the power cable. The deep water sections of the survey area are relatively free of engineering constraints, and thick unconsolidated sediments should provide adequate protection if the cable is to be buried. This portion of the route is however not without lake bed features such as dredge spoils, shellfish beds, and shallow sub-bottom gas. In the shallow water sections of the survey, the unconsolidated sediments thin and are not present in some places where bedrock is at the lake bed. Lake bed features in the shallow water portions of the proposed cable route include boulders, shallow depression features, and areas of shallow sub-bottom gas. Alternative Route 1 Alternative cable routes were proposed by CSR in order to avoid the bedrock shoal located near Wolfe Island. The alternative routes were determined using CHS bathymetry data to place the cable in the deepest possible water depths in order to maximize the amount of unconsolidated sediments in which the cable can be buried. The alternative routes are included in Enclosure 1, and CSR has been informed by the client that alternative route 1 has been selected for the cable route. This route alters the cable approximately 380 metres to the southwest around the bedrock shoal before rejoining the original proposed route. Upon clearing the shore at Wolfe Island, water depths along this route range between 3m to 5m. It should be noted that this route passes between 2 navigation buoys on the CHS Chart 2017. The navigation buoys are positioned to direct pleasure craft around the bedrock shoal, enabling them safe passage to the Wolfe Island shore. By routing the cable around the bedrock shoal, the cable route is free of any identified bathymetric shoal features for 10m on either side that could cause engineering concerns. However, in the areas where the route is altered outside of the original 200m survey corridor there is no surficial or sub-bottom data available, and therefore, it is not known if this portion of the cable route is clear of any lake bed features that may cause engineering concerns. Enclosure 4 displays interpreted profiles of the sub-bottom geology along the cable route centerline, as well as 2 wing lines. The wing lines are spaced 10m on either side of the cable route centerline, providing a 20m corridor where engineering constrains have not been identified. In the areas where the cable route is altered outside of the original 200m survey corridor, the profiles are displayed with CHS bathymetry data only.



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6.0 SUMMARY Survey operations were conducted between April 10th and 16th, 2006 onboard the CSR survey vessel “Sea Star”. The survey equipment installed on the “Sea Star” included a differential GPS positioning system, dual frequency Knudsen echo sounder, Klein 100kHz sidescan sonar, Klein 3.5 kHz Sub-bottom Profiler, Marine Magnetics, Seaspy magnetometer and an Applied Microsystems Ltd. SVPLUS sound velocimeter. Ground truth data was obtained by using the CSR surficial grab sampler and the Delta Vision Marine Video Splashcam. The bathymetry of the survey corridor ranges from 23m to as shallow as 1.0m. Water depths ranging from 16m to as deep as 23m are present across the harbor channel before it begins to shallow between Simcoe and Garden Island, and extending to the Wolfe Island shore. The bathymetry in the shallow area ranges in depths from 5m, to less than 1.5m in a bathymetric shoal 150m lakeward of Wolfe Island. The surficial sediments within the survey corridor where broken into five main units. These units are based on their signatures in the geophysical records (sidescan sonar, sub-bottom profiler and echo sounder) and ground truthed by surficial grab samples and underwater video. Units A, B and C consist of soft unconsolidated sediments such as clay and silt, and contain varying amounts of coarser material such as shell fragments, gravel sized clasts and the occasional boulder. Unit D consists of bedrock, and is present on the lake floor at the Kingston shore and the bathymetric shoal. Unit E is present at the Wolfe Island shore, and is thought to consist of a coarse till. The shallow sub-bottom geology within the survey area consists primarily of four visible reflectors as well as multiple areas of shallow gas. The northwest side of the survey area consists of a thick sedimentary sequence which includes the R1 reflector, underlain by a discontinuous, deeper reflector (R3). In the shallow area between Simcoe and Garden Islands the sub-bottom sediments become shallow. Three sub-bottom reflectors are visible in this area, and consist of a fine, unconsolidated surficial sedimentary sequence, underlain by coarser sedimentary units R2, and R3. Bedrock is visible on the seafloor at the bathymetric shoal. It is possible that deeper sedimentary units are present in the survey area beneath the reflectors mapped in this report due to the sub-bottom profiler’s inability to penetrate coarse material such as till. A number of features have been identified on the lake floor within the area surveyed. These features include dredge spoils, shellfish beds, scours, shallow depressions, boulders, an outflow/intake pipe, and the wreck of the KPH. Identified targets that are potential engineering concerns have been listed in table 3.1. CHS has identified the Kingston area to be one of erratic magnetic readings, and has labeled the area as a magnetic anomaly on the Hydrographic Navigation Chart 2017.



46

The regional magnetic flux data collected over the survey area by CSR contained large variations as a result of the known anomaly however, two additional anomalous values appearing as spikes in the data were also identified. There were no visible targets in the sidescan sonar data that corresponds to the magnetic anomalies, and the CHS navigational chart does not indicate the presences of any know sub-marine cables in the area. Based upon the analysis of all the geophysical data available from the survey area, the underlying geology may cause some challenges to the installation of the power cable. The deep water sections of the survey area are relatively free of engineering constraints, and thick unconsolidated sediments should provide adequate protection if the cable is to be buried. This portion of the route is however not without lake bed features such as dredge spoils, shellfish beds, and shallow sub-bottom gas. In the shallow water sections of the survey, the unconsolidated sediments thin and are not present in some places where bedrock is visible at the lake bed. Lake bed features in this section of the survey area include boulders, shallow depression features, and areas of shallow sub-bottom gas. Due to the presence of the bedrock shoal, 3 alternative cable routes were proposed by CSR to by pass the shoal, and to maximize the amount of unconsolidated sediment in which to bury the power cable. Alternative route 1 was selected by the client to be used as the cable route, which alters the route 380m southwest of the original centerline. Water depths along this route range between 3m to 5m. It should be noted that this route passes between 2 navigation buoys on the CHS Chart 2017 that direct pleasure craft around the bedrock shoal. Where geophysical data is available, a 20m wide corridor along the length of the cable route is present where engineering constraints have not been identified. There is no geophysical data available in the areas where the cable route is altered outside of the original 200m survey corridor.



47

7.0 RECOMMENDATIONS This section offers some recommendations for future consideration.

1. Enclosure 1 includes three alternative cable routes determined based on the bathymetry acquired from CHS field sheets. Geophysical data was not collected outside of the original 200m survey corridor during survey operations, and therefore there is no surficial or sub-bottom data covering the areas where the alternative cable routes veer outside of this corridor. Alternative cable route 1 was chosen by the client to by pass the bedrock shoal. CSR recommends that a geophysical survey be conducted to along the new route where it is outside the 200m survey corridor so that the surficial and sub-bottom geology across the entire route is known.

2. The acquisition of sub-surface geology was successful over the survey area using

the 3.5 kHz sub-bottom profiler. Due to its inability to penetrate coarse sediments, it is possible that deeper sedimentary units are present in the survey area beneath the reflectors identified in this report. If a stronger seismic system such as a surface towed boomer was used, deeper penetration through coarse materials could be achieved.

3. Ground truthing was obtained through surficial grab samples and video footage

collected over the survey area. Both systems proved invaluable to the interpretation of the surficial sediments and confirming the presence of bedrock at the seafloor. There was however no ground truth information collected to correspond with the sub-bottom data. If core samples were collected over strategic positions, especially in the shallow areas of the survey, more precise unit descriptions could be made concerning the consistency and lithology of the underlying units, and whether they pose a potential problem for any trenching operations being conducted while laying the power cable.

For such a program, CSR would be able to recommend areas within the survey corridor where core samples would prove most valuable based on the current sub-bottom data set.



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8.0 REFERENCES Canadian Hydrographic Service, Department of Energy, Mines and Resources. Field Sheet 3664, Howe Island to Kingston, 1970. Canadian Hydrographic Service, Department of Fisheries and Oceans Canada. Field Sheet 8078, Kingston Harbour to Salmon Island, 1981. Canadian Hydrographic Service, Fisheries and Oceans Canada. Chart 2017, Kingston Harbour and Approaches. July 13, 1990 ed. Canadian Ice Service, Environment Canada {online}. Lake Ice Climatic Atlas Great Lakes 1973-2002. Available at http://iceglaces.ec.gc.ca/App/WsvPageDsp.cfm?ID=11680&Lang=eng Accessed May, 2006. Fisheries and Oceans Canada {online}. Marine Environmental Data Services Available at http://www.meds-sdmm.dfo-mpo.gc.ca/meds/Prog_Nat/TWL_apps_e.htm Accessed May, 2006 Josenhans, H.W., Zevenhuizen,J., and MacLean, B., 1990. Preliminary Seismostratigraphic interpretations from the Gulf of St. Lawrence. Current Research, Part B, Geological Survey of Canada, Paper 90-1B, p. 59-75. Josenhans and Zevenhuizen, 1993. Quaternary Sediment Maps of the Gulf of St Lawrence. Geological Survey of Canada, Open File Report 2700, v1. National Oceanic Atmospheric Administration {online}. NOAA Great Lakes Environmental Research Laboratory. Available at http://www.glerl.noaa.gov/. Accessed May, 2006 Northern Tech Diver, Ontario’s Premier Source for Scuba Training & Gear. Available online at: Http://www.northerntechdiver.com/wrecks/kph/kph.php. Accessed May 29, 2006.

Documents

CANADIAN SEABED RESEARCH LTD. WOLFE ISLAND CABLE …k7waterfront.org/files/WolfeIslandWindProject/...Wolfe_Island_rpt.pdf · WOLFE ISLAND CABLE ROUTE SURVEY Geophysical Survey Results