APPENDIX I WORLEYPARSONS GPR REPORT (ISSUED IN ELECTRONIC FORM)

Transcription

1 Angela MacPherson, TCPL July 27, 2011 Northwest Mainline Loop, Timberwolf Section Geotechnical Assessment Report Project: APPENDIX I WORLEYPARSONS GPR REPORT (ISSUED IN ELECTRONIC FORM) K:\Projects\0098 TCPL\101 NWML Loop\01 Timberwolf Section\06 Geotechnical Assessment Report\FINAL_NWML_Timberwolf_Geotech_Report.doc BGC ENGINEERING INC.

2 2011 Geophysical Investigation for Muskeg Delineation Using Ground Penetrating Radar (GPR) F April 2011 WorleyParsons Canada 200, 9908 Franklin Avenue Fort McMurray, AB T9H 2K5 CANADA Phone: Facsimile: Copyright 2011 WorleyParsons

3 PROJECT F GEOPHYSICAL INVESTIGATION FOR MUSKEG DELINEATION USING GROUND PENETRATING FILE LOC.: FORT MCMURRAY REV DESCRIPTION ORIG REVIEW WORLEY- PARSONS APPROVAL DATE CLIENT APPROVAL DATE A Issued for review L. Graham P. Bauman P. Bauman 28-Apr-11 0 Issued as final L. Graham P. Bauman P. Bauman 29-Apr-11 R:\BGC Engineering Inc\F \12.0_Reports\12.2_Final\F GP-REP-2011 GPR Report-Rev0.doc Page i F : Rev 0 : 29 April 2011

4 Disclaimer The information presented in this document was compiled and interpreted exclusively for the purposes stated in Section 1 of the document. WorleyParsons provided this report for BGC Engineering Inc. solely for the purpose noted above. WorleyParsons has exercised reasonable skill, care, and diligence to assess the information acquired during the preparation of this report, but makes no guarantees or warranties as to the accuracy or completeness of this information. The information contained in this report is based upon, and limited by, the circumstances and conditions acknowledged herein, and upon information available at the time of its preparation. The information provided by others is believed to be accurate but cannot be guaranteed. WorleyParsons does not accept any responsibility for the use of this report for any purpose other than that stated in Section 1 and does not accept responsibility to any third party for the use in whole or in part of the contents of this report. Any alternative use, including that by a third party, or any reliance on, or decisions based on this document, is the responsibility of the alternative user or third party. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of WorleyParsons. Any questions concerning the information or its interpretation should be directed to Linden Graham at or Paul Bauman at F GP-REP-2011 GPR Report-Rev0.doc Page ii F : Rev 0 : 29 April 2011

5 CONTENTS 1. INTRODUCTION SURVEY PARAMETERS Geophysical Data Acquisition Positional Survey Control Data Processing RESULTS Physical Properties and Interpretation of Results Geophysical Sections GPR Depth to Interface SUMMARY CLOSURE REFERENCES...10 Tables within Text TABLE A TABLE B NWML MUSKEG LOCATIONS (WHERE DEPTH OF MUSKEG IS GREATER THAN 2.0 MBGS)... 5 TANGHE CREEK MUSKEG LOCATIONS (WHERE DEPTH OF MUSKEG IS GREATER THAN 2.0 MBGS)... 6 Figures FIGURE 1 SITE LOCATION MAP FIGURE 2 NWML BASEMAP 1 FIGURE 3 NWML BASEMAP 2 FIGURE 4 NWML BASEMAP 3 FIGURE 5 NWML BASEMAP 4 F GP-REP-2011 GPR Report-Rev0.doc Page iii F : Rev 0 : 29 April 2011

6 FIGURE 6 NWML BASEMAP 5 FIGURE 7 NWML BASEMAP 6 FIGURE 8 NWML BASEMAP 7 FIGURE 9 NWML BASEMAP 8 FIGURE 10 TANGHE CREEK BASEMAP 1 FIGURE 11 TANGHE CREEK BASEMAP 2 FIGURE 12 TANGHE CREEK BASEMAP 3 FIGURE 13 TANGHE CREEK BASEMAP 4 FIGURE 14 TANGHE CREEK BASEMAP 5 FIGURE 15 TANGHE CREEK BASEMAP 6 FIGURE 16 FIGURE 17 FIGURE 18 FIGURE 19 FIGURE 20 FIGURE 21 FIGURE 22 FIGURE 23 FIGURE 24 FIGURE 25 FIGURE 26 FIGURE 27 FIGURE 28 FIGURE 29 FIGURE 30 FIGURE 31 NWML-1 NWML-2 NWML-3 NWML-4 NWML-5 NWML-6 NWML-7 NWML-8 NWML-9 NWML-10 NWML-11 NWML-12 TC-1 TC-2 TC-3 TC-4 F GP-REP-2011 GPR Report-Rev0.doc Page iv F : Rev 0 : 29 April 2011

7 FIGURE 32 FIGURE 33 FIGURE 34 FIGURE 35 FIGURE 36 FIGURE 37 FIGURE 38 FIGURE 39 FIGURE 40 FIGURE 41 FIGURE 42 FIGURE 43 FIGURE 44 TC-5 TC-6 TC-7 TC-8 TC-9 TC-10 TC-11 TC-12 TC-13 TC-14 TC-15 TC-16 TC-17 F GP-REP-2011 GPR Report-Rev0.doc Page v F : Rev 0 : 29 April 2011

8 1. INTRODUCTION BGC Engineering Inc. retained WorleyParsons to conduct a geophysical survey to delineate the thickness of muskeg over two existing pipeline right-of-ways (ROW) south of Rainbow Lake, Alberta, and west of Manning, Alberta (Figure 1). The northwest main line (NWML) trends in a north-south direction and is located approximately 30 km southwest of Rainbow Lake, Alberta. The Tanghe Creek ROW trends in a west-east direction located approximately 100 km west of Manning, Alberta. This report provides a summary of the geophysical investigations completed in these areas. The objective of the survey was to delineate areas of thick muskeg. This information was to be used in the construction of new pipelines. Ground penetrating radar (GPR) can effectively delineate an interface (i.e. muskeg to sand or muskeg to clay) using reflections from two mediums with different dielectric constants. The most significant control on the dielectric constant is the water content. F GP-REP-2011 GPR Report-Rev0.doc Page 1 F : Rev 0 : 29 April 2011

9 2. SURVEY PARAMETERS Georeferenced basemaps for the survey was created using coordinates collected during the geophysical investigation (Figures 2-15). The 2011 program consisted of two geophysical transects, the NWML (Figures 2-9) collected north to south, and the Tanghe Creek Line (Figures 10-15) collected from west to east. All GPR transects were collected for the objective of delineating muskeg thickness. 2.1 Geophysical Data Acquisition GPR data were collected using the Sensors and Software pulseekko PRO 100MHz system as well as the Noggin250, combined with a high resolution differential GPS. The GPR antennas were attached to a plastic sled and pulled behind a tacked Argo. The antenna separation was kept constant at 1.0 m. In general, the time window was set between 300 nanoseconds (ns) and 500 ns, and the sampling time interval was set to 0.8 seconds, in order to image to approximately 4 to 7 metres below ground surface (mbgs). Sixteen stacks were collected for each trace. All GPR sections were collected between February 26 and March 15, Positional Survey Control WorleyParsons established geophysical survey location control using a Trimble GeoXH global positioning system (GPS). During the survey, RTK and post-processed GPS control points were collected every meter in Universal Transverse Mercator (UTM) coordinates referenced to the 1983 North American Datum (NAD83), Zone 11N. The pulseekko PRO and Noggin250 was synchronized to the GPS, enabling a GPS point to be collected every 10 radar traces. For final processing, topography referenced to metres above seal level (masl) was incorporated with the datasets. Topographic and location data from a LIDAR dataset were referenced at a station interval of approximately 5 m. Data collection was continuously monitored in the field by a geophysicist for quality control purposes. Upon completion of a survey line, preliminary processing of the geophysical data was performed to ensure quality standards were met. 2.3 Data Processing GPR Slice Version 7.0 software package (Goodman, 2010; was used to process the GPR datasets. All GPR datasets were processed using the same processing flow which included applying a signal saturation correction filter to the data, adjusting all GPR profiles to a common travel time window, and aligning the traces at a travel time of zero. A time-varying gain was applied in order to enhance the display of the reflectors of interest (i.e. the base of the muskeg). The F GP-REP-2011 GPR Report-Rev0.doc Page 2 F : Rev 0 : 29 April 2011

10 GPR profiles were then converted to a depth, based on a unique velocity of m/ns for the NWML and m/ns for the Tanghe Creek Line. The velocities of m/ns and m/ns are each an average estimate for an entire GPR profile. The average velocity of the first tens of centimetres of the subsurface, represented by snow cover, is generally higher than 0.1 m/ns. Below the snow cover, the muskeg is likely thawed or water saturated, and the overall electromagnetic velocity of the medium will be lowered. Saturated sand and clay deposits typically have a propagation velocity of 0.06 m/ns (Annan 2003). An average velocity of m/ns and m/ns for the GPR sections was considered appropriate in this case after ground truthing surveys were completed. The topographic dataset used in conjunction with the GPR datasets was completed using highresolution LIDAR survey data provided by Midwest Surveys (Midwest 2011). F GP-REP-2011 GPR Report-Rev0.doc Page 3 F : Rev 0 : 29 April 2011

11 3. RESULTS 3.1 Physical Properties and Interpretation of Results GPR is a shallow, non-invasive, subsurface investigation technique capable of mapping interfaces in a cross-sectional format. GPR measures the propagation time of high frequency electromagnetic pulses that are reflected from interfaces between materials of different electrical properties. Typically, radar reflections occur with abrupt changes in moisture content, grain size, porosity, soil texture, or off of massive buried objects such tree trunks, boulders, pipelines or underground storage tanks. GPR is analogous to the reflection seismic technique that uses the travel time of acoustic pulses to identify interfaces. GPR is best suited to investigations in electrically resistive environments such as muskeg or coarse-grained materials, i.e. sand size or larger. GPR investigations for geologic applications can be performed at frequencies ranging from 12.5 MHz to 1000 MHz. Higher frequencies provide data of higher vertical resolution, while lower frequencies improve the depth of investigation. For example, 1000 MHz would provide a vertical resolution of approximately 5 cm, and a depth of investigation of approximately.75 m in a sandy soil. Conversely, 12.5 MHz antennas may provide a depth of investigation of 40 m or greater, with a vertical resolution of 3 m in granular overburden. The general site geology of the region is largely derived from lacustrine clay and slity clay (Lindsay et al., 1959). Better-drained areas are characterized by soils of either the Solonetzic or Podzolic Orders. Poorly-drained areas are generally characterized by Orthic Gleysols. 3.2 Geophysical Sections GPR data are presented as two-dimensional profiles displayed in continuous greyscale, with vertical exaggeration. Although every effort was made to keep the Argo at a constant speed during data collection, the collection speed is inevitably variable; therefore, GPR cross-sections are referenced with respect to traces with coordinates plotted beneath each section. Due to pulseekko PRO system limitations, surface features, and equipment troubleshooting, GPR datasets were collected as a series of lines of different lengths. Sections are plotted on the same scale with a vertical exaggeration of approximately 50:1 for the pulseekko PRO and 37:1 for the Noggin250. Some GPR profiles may be slightly discontinuous in some areas, for reasons including pausing/stopping of data collection, breaking fibre optic cables, loss of GPS satellite coverage, etc. The pulseekko PRO 100 MHz antennas were utilized on all lines excluding Figure 29 to Figure 34, which were collected using the Noggin 250 MHz antennas. pulseekko PRO 100 MHz antennas were superior to the Noggin 250 MHz antennas in imaging the muskeg/till interface. Strong multiples in the first 1.0 m depth of the Noggin F GP-REP-2011 GPR Report-Rev0.doc Page 4 F : Rev 0 : 29 April 2011

12 250 MHz made processing and interpretation more difficult when compared to the pulseekko PRO. Following one day of Noggin 250 MHz data collection, all lines were collected with the pulseekko PRO 100 MHz antennas. Table A and Table B highlight the coordinates for line segments of muskeg depth greater than 2.0 mbgs, as well as maximum depth of organic material for the NWML and Tanghe Creek Line, respectively. Coordinates are referenced for the NWML from north to south, and west to east for the Tanghe Creek Line. Basemap figure numbers and GPR section figures are listed for reference purposes. Table A NWML Muskeg Locations (where depth of muskeg is greater than 2.0 mbgs) Easting Start Northing Start Easting End Northing End Maximum Depth of Muskeg (mbgs) Basemap Location (Fig #) GPR Section (Fig #) F GP-REP-2011 GPR Report-Rev0.doc Page 5 F : Rev 0 : 29 April 2011

13 Easting Start Northing Start Easting End Northing End Maximum Depth of Muskeg (mbgs) Basemap Location (Fig #) GPR Section (Fig #) Table B Tanghe Creek Muskeg Locations (where depth of muskeg is greater than 2.0 mbgs) Easting Start Northing Start Easting End Northing End Maximum Depth of Muskeg (mbgs) Basemap Location (Fig #) GPR Section (Fig #) F GP-REP-2011 GPR Report-Rev0.doc Page 6 F : Rev 0 : 29 April 2011

14 Easting Start Northing Start Easting End Northing End Maximum Depth of Muskeg (mbgs) Basemap Location (Fig #) GPR Section (Fig #) GPR Depth to Interface Databases were constructed consisting of the depth of the reflector (i.e. interpreted bottom of the muskeg) with respect to its line position. These depths were then gridded using a minimum curvature subroutine, and used as an overlay on the basemap. This overlay is displayed with a colour scheme, with shallow depths indicated by cool colours (e.g. blues), and greater depths indicated by warm colours (e.g. white and orange). A colour bar accompanies all maps for reference. The depth to the interface for the NWML (Figures 2-9) area ranges between 0.5 mbgs and greater than 5.5 mbgs, with the section of deepest muskeg located at E; N. The depth to muskeg interface for the Tanghe Creek (Figures 10-15) area ranges between 0.5 and greater than 5.9 mbgs, with the section of deepest muskeg located at E; N. F GP-REP-2011 GPR Report-Rev0.doc Page 7 F : Rev 0 : 29 April 2011

15 4. SUMMARY The following conclusions are drawn from the geophysical investigation: approximately km of GPR data were collected with the pulseekko PRO100 MHz antennas, with approximately 14.5 km of data collected with the Noggin 250 MHz antennas; maximum depths of organic material were interpreted to be up to 5.5 mbgs on the NWML, and up to 5.9 mbgs on the Tanghe Creek Line; geologic information gathered through the drilling program, following the GPR survey, described and confirmed the exact nature and composition of the interfaces highlighted in the GPR dataset, and was used to refine propagation velocities and interpretation; ice lenses, frost layers, distinct soil horizons, etc. may in some circumstances, cause reflectors similar in appearance to a reflector indicating the bottom of muskeg; and GPR was successful in imaging subsurface features in the NWML and Tanghe Creek area, with GPR data being of high quality over most areas. F GP-REP-2011 GPR Report-Rev0.doc Page 8 F : Rev 0 : 29 April 2011

16 5. CLOSURE We trust that this report satisfies your current requirements and provides suitable documentation for your records. If you have any questions or require further details, please contact the undersigned at any time. Report Prepared by Linden Graham, B.Sc., Geoph.I.T. Geophysicist Senior Review by Paul Bauman, M.Sc., P.Eng., P.Geoph. Technical Director, Geophysics APEGGA Permit to Practice No. P0725 Prairie Business Unit Infrastructure & Environment WorleyParsons Canada Services Ltd. F GP-REP-2011 GPR Report-Rev0.doc Page 9 F : Rev 0 : 29 April 2011

17 6. REFERENCES Annan, A.P., Ground Penetrating Radar: principles, procedures, and applications. Sensors and Software Inc., Mississauga, ON. Goodman, D., Geophysicist PhD. Geophysical Archaeometry Laboratory, Gypsy Ln., Woodland Hills, CA 92364, Lindsay, J.D., S. Pawluk, and W. Odynsky, Exploratory Soil Survey of Alberta Map Sheets 84-J, 84-K, and 84-L. Research Council of Alberta. Preliminary Soil Survey Report Midwest, NWML and Tanghe Creek Lidar; Personal communication with Scott Boulanger. F GP-REP-2011 GPR Report-Rev0.doc Page 10 F : Rev 0 : 29 April 2011

18 Figures F GP-REP-2011 GPR Report-Rev0.doc Figures F : Rev 0 : 29 April 2011

19 Twp ± 58 U V V U Twp Twp. 93 Twp U V Twp U V Twp Twp. 97 Twp Twp. 99 Twp U V Twp. 101 Twp Twp. 103 Twp Twp. 105 Twp Twp. 107 Twp RAINBOW LAKE Twp Twp MANNING NWML Highway Tanghe Creek Road Twp. 91 Twp. 90 Legend 690 U V City/Town Rge. 13 Rge. 12 Twp. 89 Provincial Boundary Rge. 11 Rge. 10 Rge. 9 Rge. 8 Rge. 7 Rge. 6 Rge. 5 Rge. 4 Rge. 3 Rge. 2 Rge. 1 Rge. 25 Rge. 24 Rge. 23 Rge. 22 Infrastructure & Environment 0 1:600,000 BGC ENGINEERING INC GEOPHYSICAL INVESTIGATION FOR MUSKEG DELINEATION NWML AND TANGHE CREEK GOUND PENETRATING RADAR UTM Nad 83 Zone 11 SITE LOCATION MAP 5 10 Kilometers APR-11 Image Source: Bing Maps Aerial date.. edited by C.H. drawn by L.G. app by PREPARED SOLELY FOR THE USE OF OUR CLIENT AS SPECIFIED IN THE ACCOMPANYING REPORT. NO REPRESENTATION OF ANY KIND IS MADE TO OTHER PARTIES WITH WHICH WORLEYPARSONS HAS NOT ENTERED INTO A CONTRACT. PROJECT NUMBER: F FIGURE: 1 FILE: Q:\F \F \ArcGIS\MXDs\Site_Location.mxd Issued by Edmonton GIS U V