DOCUMENT APPROVAL SHEET
DOCUMENT TYPE
FINAL REPORT
CLIENT
MORMUGAO PORT TRUST,GOA
PREPARED FOR
MORMUGAO PORT TRUST,GOA
PROJECT TITLE
SUB BOTTOM PROFILING SURVEY FOR THE AREA WEST OF THE BREAK
WATER LINE, OFF GOA, WEST COAST OF INDIA .
DOCUMENT NO.
Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009
PREPARED BY
JITENDRA AHER
CHECKED BY
P.S. BANSOD
PREPARED AT
DBM GEOTECHNICS AND CONSTRUCTIONS PVT. LTD
B/301, CENTAUR HOUSE ,3rd FLOOR
SHANTINAGAR INDUSTRIAL ESTATE,
NEAR GRAND HYATT HOTEL,VAKOLA,
SANTACRUZ(EAST) MUMBAI.-400055
DISTRIBUTION
MORMUGAO PORT TRUST,GOA. (1 Copy)
_____________________
AUTHORISED SIGNATORY
PREPARED BY
REV.
NO.
DATE
DESCRIPTION
NAME
0
09/03/2009
Sub Bottom Profiling Survey for the Area West of
Break Water line, Marmagao port, off Goa, West
Coast of India for MPT,Goa.
DR.S
SIGN.
CHECKED BY
NAME
JDA
SIGN.
APPROVED BY
NAME
PSB
SIGN.
LIST OF CONTENTS
Page
1
SUMMARY OF RESULTS............................................................................................................................... 5
2
5
INTRODUCTION ............................................................................................................................................. 6
GENERAL........................................................................................................................................................ 6
SURVEY SCOPE & REQUIREMENTS ........................................................................................................... 6
LOCATION ...................................................................................................................................................... 6
DESCRIPTION OF THE SURVEY .................................................................................................................. 6
SCOPE OF WORK .......................................................................................................................................... 6
IMPLEMENTATION STRATEGY..................................................................................................................... 7
RESOURCES .................................................................................................................................................. 7
PERSONNEL................................................................................................................................................... 7
EQUIPMENT ................................................................................................................................................... 7
VESSEL ........................................................................................................................................................... 8
DELIVERABLES ............................................................................................................................................. 8
6
QA/QC PROCEDURES FOR EQUIPMENT .................................................................................................... 9
7
CONTROL OF WORK................................................................................................................................... 10
PROJECTION PARAMETERS ...................................................................................................................... 10
HORIZONTAL CONTROL ............................................................................................................................. 10
VERTICAL CONTROL ................................................................................................................................... 11
ECHO SOUNDER ......................................................................................................................................... 11
SIDE SCAN SONAR ...................................................................................................................................... 11
SUB-BOTTOM PROFILER SYSTEM ............................................................................................................ 13
SHALLOW SOIL SAMPLING ........................................................................................................................ 13
PRE PLOTS/RUN-IN-PLOTS ........................................................................................................................ 14
PROCESSING OF DATA .............................................................................................................................. 14
PROGRESS REPORT .................................................................................................................................. 14
SURVEY OPERATION AND PROCEDURE ................................................................................................. 14
PRE-MOBILISATION ACTIVITIES ................................................................................................................ 14
MOBILISATION ............................................................................................................................................. 14
INSPECTION ACTIVITIES ............................................................................................................................ 15
PROCEDURE OF SURVEY .......................................................................................................................... 15
CALIBRATION ............................................................................................................................................... 15
SAFETY ......................................................................................................................................................... 15
DATA QUALITY CONTROL .......................................................................................................................... 15
DEMOBILISATION ........................................................................................................................................ 15
DETAILED RESULTS ................................................................................................................................... 16
GENERAL...................................................................................................................................................... 16
HORIZONTAL CONTROL ............................................................................................................................. 16
VERTICAL CONTROL ................................................................................................................................... 16
BATHYMETRY .............................................................................................................................................. 16
SEABED FEATURES .................................................................................................................................... 17
SHALLOW STARTIGRAPHY ........................................................................................................................ 17
SHALLOW SOIL SAMPLING ........................................................................................................................ 18
2.1
3
3.1
3.2
3.3
3.4
4
4.1
4.2
4.3
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
7.9
7.10
8
8.1
8.2
8.3
8.4
8.5
8.6
8.7
8.8
9
9.1
9.2
9.3
9.4
9.5
9.6
9.7
Final Report on Sub Bottom Profilling Survey
Off Goa, West Coast of India
For Mormugao Port Trust,Goa
Final report No: Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009
2
DBM GEOTECHNICS AND CONSTRUCTIONS PVT.LTD.MUMBAI
APPENDICES
APPENDIX A
APPENDIX B
APPENDIC C
C1
APPENDIX D
APPENDIX E
APPENDIX F
APPENDIX G
CHORONOLOGICAL SUMMARY OF EVENTS (DSR’S)
VESSEL OFFSET DIAGRAM
SYSTEM CALIBRATIONS
POSITIONING SYSTEM
OBSERVED TIDAL READINGS
ON-BOARD SOIL SAMPLE ANALYSIS
LABORATORY SOIL SAMPLE ANALYSIS
EXTRACTS FROM FIELD RECORDS
LIST OF DRAWINGS
DRAWING NUMBER
DESCRIPTION
SCALE
No.
Charts
Rev.
Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009/1153
BATHYMETRY CHART
1: 2000
1
Rev 0
Job.no.2337 Finrep (Rev. 0) dt. 09/03/20091154
SEABED FEATURE CHART
1: 2000
1
Rev 0
Job.no.2337 Finrep (Rev. 0) dt. 09/03/20091155
SEABED AND GEOLOGICAL PROFILES
H:1: 2000
V:1:200
1
Rev 0
Total Number of Drawings
Final Report on Sub Bottom Profilling Survey
Off Goa, West Coast of India
For Mormugao Port Trust,Goa
Final report No: Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009
3
3
DBM GEOTECHNICS AND CONSTRUCTIONS PVT.LTD.MUMBAI
Location Map
Final Report on Sub Bottom Profilling Survey
Off Goa, West Coast of India
For Mormugao Port Trust,Goa
Final report No: Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009
4
DBM GEOTECHNICS AND CONSTRUCTIONS PVT.LTD.MUMBAI
1
SUMMARY OF RESULTS
DBM Geotechnics and Constructions Pvt.Ltd,Mumbai was required to conduct Sub bottom profiling at
west of break water line, Marmagao port Trust off,Goa, West coast of India. Survey data acquisition
operations were conducted during 16th to 18th February, 2009.
All water depths wherever mentioned in this report refer to chart datum.
General bathymetry within the survey area shows smooth seabed and the sloping towards Northwest
gradually. Maximum depth in the survey area is 14.8 m on the NW corner of the survey area and minimum
depth is 2.5 mtrs near SW corner of the survey area. From shoreline up to distance of 250 mtrs undulated
seabed is recorded and depth varying from 2.5 mtrs to 9.8 mtrs. Remaining survey area is recorded as
smooth seabed depth varying from 9.1 mtrs to 14.8 mtrs. Bathymetry along the breakwater is recorded 4.6
mtrs and maximum is 10. 7 mtrs. General trend of the contour runs from Northeast to Southwest and the
depth reaches to 10 mtrs within distance of 250 mtrs from shoreline.
In general, Side scan sonar reveals an almost a flat seabed with varying reflectivity as follows:
Type 1 :
Type 2 :
Type 3 :
Type 4 :
Low reflective sediments (Silty clays)
Medium to high reflective lineations (Sand waves)
Highly reflective surface (Weathered lateritic
Sands)
Sand ripples overprinted on Type-1.
bed rock overprinted by fine
Type 1 : These sediments occur on the seabed predominantly all over the surveyed area in small patches
except near the shore line where exposures of basaltic and lateritic rocks can be seen.
Type 2 : Medium to high reflective lineations i.e. sand waves are found distinctly all along the Channel in a EW trend between Eastings 368800 & 370400.
Type 3 : Highly reflective surface represents weathered lateritic and basaltic rock exposures over which silty
clay and fine sands are deposited. These are found all along the shoreline.
Type 4 : Sand ripples occur in the middle of the surveyed corridor and are overprinted on Type-1 sediments.
Apart from this no other significant features / items of debris were found within the survey corridor which could
be hazardous to the proposed dredging operations.
The shallow geological successions within the window examined by the analogue data in the surveyed
area can be described as follows:
Unit - 1 :
Unit - 2 :
Unit - 3 :
Unconsolidated & cohesive silty clays (occurs as veneer all along the survey area)
Fine to medium sand (occurs predominantly in the northwest quadrant of the survey area)
Comprise highly weathered bedrock (lateritic and basaltic rocks) admixed with compact silty
clay (occurs as along the survey area) whose base cannot be identifiable from the survey
records
No anomalies associated with magnetic objects were recorded within the site survey corridor.
Ten drop cores/grab samples were collected covering whole survey area and they confirm the geophysical
survey results.
Final Report on Sub Bottom Profilling Survey
Off Goa, West Coast of India
For Mormugao Port Trust,Goa
Final report No: Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009
5
DBM GEOTECHNICS AND CONSTRUCTIONS PVT.LTD.MUMBAI
2
2.1
INTRODUCTION
GENERAL
M/s. MORMUGAO PORT TRUST GOA , intended to carryout Sub bottom profiling survey for the area
west of break water off Goa for conducting the feasibility of dredging operation.This document details the
final report on sub bottom profiling survey carried out by DBM GEOTECHNICS AND CONSTRUCTIONS PVT
LTD., MUMBAI.
These survey services comprise of the provision of suitable personnel and equipment in order to obtain,
interpret and report on bathymetry, morphological and shallow stratigraphy within the survey corridors. Survey
lines were spaced 100m intervals in North–South direction and cross lines were spaced at 200m interval in
East-West direction. Echosounder, Side scan sonar and sub-bottom profiler system were deployed for
carrying out surveys. Side scan sonar was operated with range scale of 100m either side of survey line.
Gravity corer was used for collection of soil samples Observed tides of Goa were used to reduce raw water
depth to chart datum.
Surveys were carried out between 16th Feb and 18th Feb 2009.
Quality control, processing and preliminary data interpretation were undertaken at the site and on-board the
survey boat during the operations, ensuring that the survey specifications were fully met with.
3
SURVEY SCOPE & REQUIREMENTS
3.1
LOCATION
The survey area lies off Goa, West Coast of India between Lat 150 08’N to 150 20’N and Long 740 00’ E to 740
10’ E.
3.2
DESCRIPTION OF THE SURVEY
Sub bottom profiling surveys were to be conducted by deploying Echo sounder, Side scan sonar and subbottom profiler (pinger).
Differential Global Positioning System (DGPS) was to be used for providing positioning to the survey vessel.
3.3
SCOPE OF WORK
The Scope of Work provided by the client through Work Order No.CE/WKS-756/5996 dated 31.01.09 as
follows:




Collection of shallow seismic profile (19Km)
Collection of echo sounder profile (19Km)
Collection of side scan profile (19Km)
Collection of shallow soil samples (10 in nos)
DGPS positioning system, Echo sounder, Sub bottom profiler and side scan sonar to be used for the
surveys. Side scan to be operated with the range scale of 100m either side of the survey line. Gravity corer
to be used for the collection of the soil samples. Observed tide to be used for reducing the raw water depth
to chart datum.
Final Report on Sub Bottom Profilling Survey
Off Goa, West Coast of India
For Mormugao Port Trust,Goa
Final report No: Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009
6
DBM GEOTECHNICS AND CONSTRUCTIONS PVT.LTD.MUMBAI
3.4
IMPLEMENTATION STRATEGY
The following were to be provided by DBM as a minimum to complete the job as per specifications.







4
4.1
Survey vessel was to be provided by DBM to carry out the survey
Qualified personnel to carry out the entire job, all survey equipment, tools to complete the job to
the entire satisfaction to the Client Representative and in accordance with the requirements of the
tender document and relevant specification.
Arrangement for mob and demob of equipment and personnel.
DBM to be responsible for the safety and maintenance of his equipment, personnel and shall
carry adequate spares to meet all contingency requirements.
DBM obtained Port authority clearance for the survey vessel(s) deployed in the field.
DBM arranged, acquired all data, access, permissions and other activities/ services required for
and/or incidental to performing the work tendered.
All equipment, operating personnel including travel cost of operator, transportation of equipment
to and fro, surface transport and any other items required to complete the work as per the
requirements of this contract were supplied/arranged by the DBM without any liability on the part
of Client.
RESOURCES
PERSONNEL
PERSONNEL
On shore
Off-shore
----do-------do-------do-------do----
4.2
NAME
Jitendra Aher
Nivas Kank
Sharana Basava
Mangesh Gharat
Dinesh Kumar
Ashwani Sharma
FUNCTION
Asst Manager.(survey)
Party Chief/Hydrographic Surveyor
Geophysicist
Survey Engineer
Survey Engineer
Survey Engineer
Mr. Mahesh Naik, Mr. Vasco from MPT, Goa , were the client representatives at the site during entire period of
surveys.
EQUIPMENT
a) Positioning & Navigation
1
1
2
1
2
1
x
x
x
x
x
x
LEICA MX 421 DGPS combined high performance beacon receiver
Power supply for above
Computer with Qinsy Navigation and Data logging Bar Check
KVH 1000 Series digital Fluxgate Gyro
Computer system + monitors ( one spare)
Remote helmsman monitor & Fix Box
b) Echo sounder System
1
1
1
1
x
x
x
x
ODOM DF 3200 MKII Dual Channel Echosounder
Dual frequency transducer 24khz / 200 kHz + mounting bracket & base plate
Bar Check, Computer Interface, 12 V Power Supply & Generator
SMCS-108 Heave Compensator
Final Report on Sub Bottom Profilling Survey
Off Goa, West Coast of India
For Mormugao Port Trust,Goa
Final report No: Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009
7
DBM GEOTECHNICS AND CONSTRUCTIONS PVT.LTD.MUMBAI
c) Side Scan Sonar System
1
1
1
x
x
x
EG & G 272TD Dual Channel (100/500 khz) Towfish c/w spares kits
Edgetech 4100P Dual frequency & Dual channel digital side scan sonar system
Tow cable (200m length)
d) Sub-bottom Profiler (Geoacoustics)
1
1
x
x
Geoacoustics sub-bottom profiler Transceiver
Geoacoustics Transducer c/w cables, mounting bracket and EPC recorder, etc
e) Soil Sampling
1
x Piston Gravity Corer
1
x Van Veen Grab Sampler
1
x Vane Shear meter
1
x Pocket Penetrometer
All accessories and spares for the effective operation of the above.
4.3
VESSEL
Boat ML Simple Simon with high manoeuverability and sufficient deck space was provided by DBM & utilized
for carrying out survey.
5
DELIVERABLES
ONE set of Final report / charts were to be submitted to client within 2 weeks after demobilization of field
survey.
The final charts in 1:2000 scale to be prepared depicting the following:
- Bathymetry & Contours
- Seabed Features
- Seabed & Geological Profiles for representative lines
Report text and charts were to cover the following:

Summary of results
Description of survey methods, procedures, equipment and instrument calibration data.
Bathymetry chart, scale 1: 2000.
Identification of any sub-sea obstructions, and seafloor instability.
Identification of sub-bottom sediment layer.
Presence of any metallic objects, debris on the seafloor.
Longitudinal geological profiles of the selected survey run lines covering whole survey area.
Summary of field activity report.
Soil data results
General conclusions and recommendations as per tender requirement.
Final charts were to be prepared in ACAD format in A-0 size and copy of the final report text and drawings
to be submitted in both soft and hard copies.
Final Report on Sub Bottom Profilling Survey
Off Goa, West Coast of India
For Mormugao Port Trust,Goa
Final report No: Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009
8
DBM GEOTECHNICS AND CONSTRUCTIONS PVT.LTD.MUMBAI
6
QA/QC PROCEDURES FOR EQUIPMENT
Following calibration methods for different equipment were carried out prior to start of surveys:
Positioning system
The DGPS positioning system was calibrated at a known location on top of DBM Workshop Building prior to
mobilized in the field. DGPS antenna was placed on the specified station and the positions were logged for
duration of 30 minutes. The observed co-ordinates were compared with the co-ordinates of the known station.
Echo sounder
The dual frequency echo sounder system were bench checked prior to mobilisation. The outboard could be
marked from the base of the transducer shoe at 0.1metre intervals (these marks were used to confirm
transducer draft once the arrangement is deployed). The Bar Check will confirm the marks at a regular interval
of one meter and that the marks are readily identifiable. The Echo sounder was interfaced to the Navigation
and Data Logging computer to confirm that the digitization of depths is operational.
Portable transducers were installed rigidly to a bracket at suitable location on the survey vessel. These were at
sufficient depth so that it should not experience the turbulence and aeration when the vessel steams at survey
speed. The depth of the transducer below waterline was ascertained by reference to present marks on the
pole.
Prior to commencing survey works, the Echosounder was calibrated against a barcheck. The procedure is to
confirm the following constants:
Tx = To establish index error (combined effect of transducer depth and delays in the recorder)
Vp = To confirm velocity of propagation of sound in saline water.
With the vessel standstill in the waters, the Bar was lowered to at least 2m below the transducer and the
nearest mark on the chain set at the water line. Once the transmission mark is set the apparent depth of the
transducer were noted on the analogue record and recorded in the deck log for future reference. Velocity of
propagation of acoustic wave in water column was assumed to be 1530m/sec. The Bar was lowered at regular
intervals to the maximum practical depth. The bar was allowed to settle at each depth. On recording the
maximum depth the Bar was similarly stepped back to the surface. The digitized depths were also checked
during the Bar calibration.
Side scan sonar
SSS sonar was dry and wet tested in the survey area prior to deployment on a survey line.
Sub bottom profiler
Sub bottom profiler was dry and wet tested in the survey area prior to deployment on a survey line.
Final Report on Sub Bottom Profilling Survey
Off Goa, West Coast of India
For Mormugao Port Trust,Goa
Final report No: Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009
9
DBM GEOTECHNICS AND CONSTRUCTIONS PVT.LTD.MUMBAI
7
7.1
CONTROL OF WORK
PROJECTION PARAMETERS
Surveys were conducted in WGS 84 spheroid, Indian Datum, Grid co-ordinates are in terms of Universal
Transverse Mercator (UTM) Projection. Details of Spheroid and Grid systems are as follows:
GEODETIC PARAMETERS
Datum
WGS 84
Spheroid
WGS 84
Semi-Major Axis (a)
6378 137.000 metres
Semi-Minor Axis (b)
6356752.314 metres
First Eccentricity Squared (e^2)
0.006694380
Inverse Flattening (1/f)
298.257223563
PROJECTION PARAMETERS
Grid Projection
Universal Transverse Mercator
Central Meridian (CM)
75 East (Zone 43)
Origin Latitude (False Lat.)
00.0
Hemisphere
North
False Easting (FE)
500000.0 m
False Northing (FN)
0.0 m
Scale Factor on CM
0.999600
Units
Metres
7.2
HORIZONTAL CONTROL
Position for the vessel during the survey was provided by LEICA MX 421 combined DGPS beacon receiver
system. Differential correction signals were received on-board during survey operations continuously from the
nearest DGPS beacon reference station (DGLL Station). These are maintained by Director General of Light
Houses and Light Ship, Govt of India. An integrated GPS/Beacon receiver with built-in antenna provided GPS
differential corrections in NMEA-0183 format for navigation with high degree of accuracy. DGPS is a combined
high performance GPS receiver and a differential beacon receiver in an extremely compact and fully
waterproof enclosure providing high accuracy by utilizing the broadcasted 283.5 – 325 KHZ frequency
differential GPS corrections from IALA (International Authority of Lighthouses Association) beacons. The
positioning data received had high reliability and integrity. The system was calibrated at a known location on
top of DBM workshop roof prior to mobilisation (See Appendix “C1” for positioning system calibration).
Navigation & Data Logging
QINSY is a world's leading software solution provider for navigation, hydrographic survey, data acquisition
and processing needs.
QINSY provides a user-friendly turnkey solution for all types of marine navigation, positioning and surveying
activities. From survey planning to data collection, data cleaning, volume calculations and chart production,
QINSY offers a seamless data flow from a large variety of hardware sensors, all the way to a complete chart
product. Qinsy runs on a standard PC platform under the Windows (NT/2000/XP) operating system. The
software is not only independent of sensor manufacturer, but also hardware independent. One is free to buy
his own off-the-shelf hardware components and QINSY will work with them. One is not tied to specific
hardware in any way.
Final Report on Sub Bottom Profilling Survey
Off Goa, West Coast of India
For Mormugao Port Trust,Goa
Final report No: Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009
10
DBM GEOTECHNICS AND CONSTRUCTIONS PVT.LTD.MUMBAI
7.3
VERTICAL CONTROL
Observed tide was provided by the client and same was used for reducing the raw water depth to chart datum
(See Appendix “D” for tidal reading and Graphs)
7.4
ECHO SOUNDER
ODOM DF3200 MKII Dual frequency Echo sounder integrated with a DGPS positioning system were used
during the entire survey to record geographically referenced bathymetric data for measuring water depths. Sea
swell were eliminated by SMC-108 motion sensor (heave compensator). Digitized data were confirmed by the
inspection of analogue records. Velocity of propagation of acoustic wave in water column was assumed
1530m/sec. Echo sounder was calibrated against bar check prior start of survey. (See Appendix C2 for bar
check calibration)
Echo sounder Settings
Frequency
Range on record
Vertical Paper scale
:
:
:
24 KHz & 200 KHz.
Auto
1:100
Data reduction and presentation
The system was operated following recommended manufacturer procedures. The vertical paper scale was set
at 1:100 and the appropriate phases were selected to display the seabed (and the heave compensator trace)
at all times. Transducer offset were logged and applied during subsequent processing. Event marks
corresponding to position fixes were generated automatically from the on-line navigation computer interface,
and passed to the analogue recorder at a regular interval. Prior to processing, the data files were backed up.
The essential Hydrographic data thus obtained were tide corrected. Bathymetry data were reduced to chart
datum-using observed tides provided by the client. After applying the tidal corrections, crosschecks were
carried out between the bathymetry at all tie-in points. The bathymetry was charted in decimal notation to the
nearest one decimal place.
The offsets of the echo sounder transducer from central reference point (GPS Antenna) on the survey vessel
were recorded for the following:



7.5
Layback
Transverse offset
Transducer depth
=
=
=
0.0m
2.5 (Stbd)
1m
SIDE SCAN SONAR
EG & G 272TD dual channel `towfish' and an EG & G 260 recorder were provided to investigate the sea floor
for morphological and other features which may interfere with dredging & installation of operations. Double
coverage and beam angle shall be such that no blind zones exist in the designated survey areas.
The graphic recorder and data processing system included dual sweep facility. The system was capable of
depicting the sonar images corrected for distortions due to tow fish height and vessel speed and at a scale,
which clearly displays the resolution of the system.
Final Report on Sub Bottom Profilling Survey
Off Goa, West Coast of India
For Mormugao Port Trust,Goa
Final report No: Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009
11
DBM GEOTECHNICS AND CONSTRUCTIONS PVT.LTD.MUMBAI
The width of the sea-floor sonar image for each recording channel is not being less than 10 centimeters.
Image correcting systems incorporated a continuous profile display of tow fish height as part of the display
format.
The sonar data processing unit and graphic recorder unit(s) were interfaced to the survey computer to accept
the following: a) Fix mark and identifiers generated synchronously with the logging of position data.
b) Smoothed vessel speed data.
Sufficient tow cable lengths were provided to permit towing of the sonar fish at a maximum height above
seabed in all parts of the survey area. The available cable length was normally be expected to exceed three
times the maximum expected water depth in the survey area.
All tow cables were measured and marked at regular intervals for lay back determination. The side scan sonar
sensor design towing characteristics, cable and vessel tow point were selected to ensure the towed fish was
adequately decoupled from any vessel pitching and rolling motion. All sonar data and associated fix mark and
fix number information were stored, permanently, on an electronic medium.
Prior to acceptance of equipment, and at any other time requested by the Company Representative, the
system was thoroughly tested. Verification tests included, but not be limited to: a) In water testing of the sonar tow fish and cable connectors.
b) Cross-talk evaluation by rub test.
c) Transducer output functionality tests.
d) Interfacing verifications.
e) Graphic recorder performance tests.
Wherever possible DBM also verified the performance of the side scan sonar system, in the area of
operations, as part of mobilisation acceptance trials, using “known” seabed installations or features as test
targets.
The 272TD towfish carries two 100 KHz and 500 KHz transducers mounted on either side. The acoustic beam
emitted from each transducer has a horizontal beam angle of 1 degree and a vertical beam of 40 degrees
tilted at 10 degrees below the horizontal. This configuration enables reflected signals to be recorded from
contacts as far as 500 metres abeam, subject to the range selected.
Side scan sonar was operated at a range scale of 100 metres either side through out the survey. The
maximum towing speed did not exceed 5-6 kmph (3 knots). The records obtained by means of this equipment
were suitable to form a complete morphological map of areas investigated.
The offsets of the side scan sonar tow-fish from a central reference point (GPS Antenna) on the survey vessel
were recorded for the following:



Layback
transverse offset
transverse offset
=
=
=
Final Report on Sub Bottom Profilling Survey
Off Goa, West Coast of India
For Mormugao Port Trust,Goa
Final report No: Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009
6.60m + Cable out
0.0 m
Varies
12
DBM GEOTECHNICS AND CONSTRUCTIONS PVT.LTD.MUMBAI
7.6
SUB-BOTTOM PROFILER SYSTEM
Geoacoustics Model 310B transceiver and Geoacoustics Model 310 side mounted Transducer Sub-bottom
Profiler c/w cables were used in all survey lines for sub-surface data acquisition. The power output, `Time
Variable Gain', Amplifier and Filter settings were set properly to give optimum resolution and necessary
seabed penetration for the prevailing geological conditions. Event marks, corresponding to position fixes at
regular intervals, were generated automatically by the navigation computer and were passed to the EPC 1086
Graphic recorder. Records were clearly annotated and cross-checked.
The offsets of the sub-bottom Profiler from a central reference point (GPS Antenna) on the survey vessel were
recorded for the following:



7.7
Layback
Transverse offset
=
=
0.0 m
2.5m (Port)
Transducer depth
=
1m
SHALLOW SOIL SAMPLING
Gravity corer having 3 m barrel fitted with an interval PVC liner and a cutting shoe at the bottom was
deployed for collecting soil samples. In case of sands, a core catcher was provided in side the shoe to
assist retention of the sample during retrieval of the sampler.
Soil samples were collected at 10 specified locations covering whole survey area. The locations of the
samples were determined by the on-board interpretation of the geophysical records and as specified by the
client. In choosing the proposed sample locations, consideration was given to areas of interest, apparent
change in surface compositions and areas where a consistent sub-bottom could be investigated by a single
sample. Samples were collected in such a way that spacing between sample locations was such that different
types of strata encountered with in the survey area were covered.
At location where sand with shell fragments/gravel is encountered and gravity corer refuses to penetrate the
seafloor on repeated attempts, grab samples were collected.
Soil sample were extruded in the field and carefully examined and visually classified on board the vessel.
Retrieved samples were tested in the on-board laboratory for classification purposes and for broad
assessment of strength. All the samples covering all types of sedimentary strata encountered along the
surveyed corridor were sealed and carefully packed for transportation to onshore laboratory for additional
examination and testing. Testing facilities on board the vessel shall include, but not limited to, the following;










Location / Job No./ Client
Date / Time
Position Fix No. / UTM Co-ordinates / Water Depth
Method of Collection
Colour
Texture
Composition
Recovery Length
In-site Vane shear test
In-site pocket penetrometer test
Final Report on Sub Bottom Profilling Survey
Off Goa, West Coast of India
For Mormugao Port Trust,Goa
Final report No: Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009
13
DBM GEOTECHNICS AND CONSTRUCTIONS PVT.LTD.MUMBAI
7.8
PRE PLOTS/RUN-IN-PLOTS
Survey lines were planned as discussed in the scope of work and pre-plots for the area was prepared prior to
commencement of survey.
The pre-plots were run on the computer while doing the survey lines. Any deviation from the prefixed lines was
flashed on the display along with the necessary course corrections to be made to adhere to the prefixed line.
This enabled the Navigator to guide the vessel to the prefixed survey line all the times. Based on this
examination an interpretation was made of the shallow geology with emphasis on the identification of
conditions potentially hazardous to installation of seabed structures or dredging operation.
7.9
PROCESSING OF DATA
The survey data logged in Qinsy format were processed in Qinsy Terra Model Processing software and finally
presented in drawing form using AutoCAD Rel.14 for windows.
7.10
PROGRESS REPORT
While on location, survey Party Chief Submited daily progress report to Client’s representative and also
convey the same to DBM office in Mumbai.
8
SURVEY OPERATION AND PROCEDURE
The following sections describe our method statement detailing the DBM approach to this project from award
to issuing of final report.
8.1
PRE-MOBILISATION ACTIVITIES
This phase is considered to be very important for the successful execution of the contract. The following items
were given detailed attention:
-
8.2
review of clients specifications and requirements;
review of proposed equipment and configuration;
preparation of project Briefing instructions for all field going and appropriate office based personnel;
review of company QMS and Health, Safety and Environmental procedures in the context of this award;
preparation of pre-plots, survey grids and tidal information in advance of field operations;
advising all clients and relevant personnel out-of-hours and duty telephone numbers;
collection of all survey logs, QMS material, stationery and consumables for the field programme.
MOBILISATION
The Project Manager liaise with operations staff, the vessel master and Party Chief to make the appropriate
arrangements to mobilise the vessel. The port of mobilisation and demobilisation for any phase of this project
were Goa and were comprise only the boarding of client representatives with survey personnel and all other
instrumentation having been previously mobilised onto the selected survey vessel.
All instrumentation were port tests which were carried out as follows:
- Satisfactory installation of the DGPS system and computation routines.
- Checking of Echo Sounder Draft Settings (Index Error), via draft check method.
- In harbour tests of all bathymetric, sonar, SBP systems.
Final Report on Sub Bottom Profilling Survey
Off Goa, West Coast of India
For Mormugao Port Trust,Goa
Final report No: Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009
14
DBM GEOTECHNICS AND CONSTRUCTIONS PVT.LTD.MUMBAI
Upon satisfactory completion of in harbour testing, the selected vessel proceeded to the initial work area.
Whilst on passage, the Party Chief convened a meeting with all survey personnel, boat crew/ and client
representative at which the clients objectives and operational parameters were discussed. Upon arrival on site,
survey sensors were deployed and acceptance tests performed as required, in order to complete mobilisation.
8.3
INSPECTION ACTIVITIES
Following completion of all offshore equipment calibrations inspection activities were commence and proceed
in accordance with the project schedule.
8.4
PROCEDURE OF SURVEY
The survey operations were commenced as per the schedule described by DBM Geotechnics and
Constructions pvt.ltd. after insitu testing and calibration of all the equipment. Survey lines were spaced at
100m in north-south direction and cross lines wee spaced at 200m in east- west direction. Echo sounder, Side
scan sonar and sub bottom profiler were run on all the survey lines. Side scan sonar was operated with the
range scale of 100m either side of survey line. Gravity corer was used for collection of soil samples. Observed
tides of Goa were provided by the client and same was used for reducing the raw water depth to chart datum.
8.5
CALIBRATION
Positioning system was calibrated at a know station at DBM Workshop building prior deployment in the field.
8.6
SAFETY
Safety was observed on the vessel while carrying out the surveys according to DBM’s HSE plan.
8.7
DATA QUALITY CONTROL
The experienced operators provided by DBM Constantly monitored data quality as the survey progresses. A
log of profiles was maintained and quality of data was noted.
8.8
DEMOBILISATION
Upon completion of all survey activities to client’s satisfaction at the final work location all survey sensors were
retrieved for final demobilisation at Goa.
Final Report on Sub Bottom Profilling Survey
Off Goa, West Coast of India
For Mormugao Port Trust,Goa
Final report No: Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009
15
DBM GEOTECHNICS AND CONSTRUCTIONS PVT.LTD.MUMBAI
9
9.1
DETAILED RESULTS
GENERAL
M/s. MORMUGAO PORT TRUST GOA , intended to carryout Sub bottom profiling survey for the area
west of break water off Goa for conducting the feasibility of dredging operation.This document details the
final report on sub bottom profiling survey carried out by DBM GEOTECHNICS AND CONSTRUCTIONS
PVT. LTD., MUMBAI.
These survey services comprise of the provision of suitable personnel and equipment in order to obtain,
interpret and report on bathymetry, morphological and shallow stratigraphy within the survey corridors. Survey
lines were spaced 100m intervals in North–South direction and cross lines were spaced at 200m interval in
East-West direction. Echo sounder, Side scan sonar and sub-bottom profiler system were deployed for
carrying out surveys. Side scan sonar was operated with range scale of 100m either side of survey line.
Gravity corer was used for collection of soil samples Observed tides at Goa were used to reduce raw water
depth to chart datum.
Surveys were carried out between 16th Feb and 18th Feb 2009.
Quality control, processing and preliminary data interpretation were undertaken at the site and on-board the
survey boat during the operations, ensuring that the survey specifications were fully met with.
9.2
HORIZONTAL CONTROL
Position for the vessel during the survey was provided by LEICA MX 421 combined beacon receiver system.
Differential correction signals were received on-board during survey operations continuously from the nearest
DGPS beacon reference station (DGLL Station) in the survey area. These are maintained by Director General
of Light Houses and Light Ship, Govt of India. An integrated GPS/Beacon receiver with built-in antenna
provided GPS differential corrections in NMEA-0183 format for navigation with high degree of accuracy.
LEICA MX 420 is a combined high performance GPS receiver and a differential beacon receiver in an
extremely compact and fully waterproof enclosure providing high accuracy by utilizing the broadcasted 283.5 –
325 KHZ frequency differential GPS corrections from IALA (International Authority of Lighthouses Association)
beacons.
9.3
VERTICAL CONTROL
Observed tides of Goa were provided by the client and same was used for reducing the raw water depth to
chart datum (See Appendix “D” for tidal reading and Graphs)
9.4
BATHYMETRY
The following text should be read in conjunction with Work Order No.CE/WKS-756/5996/dated
31.01.09/1153 and annotated data examples placed at AppendixG. All water depths mentioned in the
following paragraphs refer to chart datum.
General bathymetry within the survey area shows smooth seabed gently sloping towards Northwest gradually.
Maximum depth in the survey area is 14.8 m on the NW corner of the survey area and minimum depth is 2.5
mtrs near SW corner of the survey area. From shoreline up to distance of 250 mtrs undulated seabed is
recorded and depth varying from 2.5 mtrs to 9.8 mtrs. Remaining survey area is recorded as smooth seabed
depth varying from 9.1 mtrs to 14.8 mtrs. Bathymetry along the breakwater is recorded 4.6 mtrs and maximum
is 10. 7 mtrs. General trend of the contour runs from Northeast to Southwest and the depth reaches to 10 mtrs
within distance of 250 mtrs from shoreline.
Final Report on Sub Bottom Profilling Survey
Off Goa, West Coast of India
For Mormugao Port Trust,Goa
Final report No: Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009
16
DBM GEOTECHNICS AND CONSTRUCTIONS PVT.LTD.MUMBAI
No other bathymetric anomalies such as coral outcrops, sub marine channels, blow out craters etc were
recorded at any point within the survey corridor.
9.5
SEABED FEATURES
The following text should be read in conjunction with Work Order No.CE/WKS-756/5996 dated 31.01.09
/1154 and annotated data examples placed at Appendix F.
The distribution of seabed features and the nature of the surficial cover is primiarily determined through the
examination of side scan sonar data acquired. Gravity cores and other geotechnical information exists for the
survey area to compare the analogue survey results with the physical soil samples and statements on
sediment texture are, therefore, interpretative. Hence, qualitative analysis of the sediments is based on the
reflectivities of the surficial sediments to 100 kHz sonar frequency. Additionally, appropriate reference to the
echo sounder & sub-bottom profiler data sets within the survey corridor.
In general, Side scan sonar reveals an almost a flat seabed with varying reflectivity as follows:
Type 1 :
Low reflective sediments (Silty clays)
Type 2 :
Medium to high reflective lineations (Sand waves)
Type 3 :
Highly reflective surface (Weathered lateritic bed rock overprinted by fine
Sands)
Type 4 :
Sand ripples overprinted on Type-1.
Type 1 : These sediments occur on the seabed predominantly all over the surveyed area in small patches
except near the shore line where exposures of basaltic and lateritic rocks can be seen. Type-1 is interpreted
to comprise of fine silty clays.
Type 2 : Medium to high reflective lineations i.e. sand waves are found distinctly all along the Channel in a EW trend between Eastings 368800 & 370400.
Type 3 : Highly reflective surface represents weathered lateritic and basaltic rock exposures over which silty
clay and fine sands are deposited. These are found all along the shoreline.
Type 4 : Sand ripples occur in the middle of the surveyed corridor and are overprinted on Type-1 sediments.
Sand ripples are interpreted to be aligned in almost East-West direction indicating the predominant bottom
current sense in North-South direction. The presence of sand ripples can be an evidence of an active
sedimentary regime in which strong tidal currents erode, transport and then deposit sediments.
Apart from this no other significant features / items of debris were found within the survey corridor which could
be hazardous to the proposed dredging operations.
9.6
SHALLOW STARTIGRAPHY
The following text should be read in conjunction with Work Order No.CE/WKS-756/5996 dated
31.01.09/1155 and annotated data examples placed at Appendix G.
For the purpose of analogue data interpretation an assumed sound velocity of acoustic propagation of
1600m/sec has been adopted for the conversions of two way travel time to depth. Seabed & interpreted
geological profiles have been produced for one centerline passing through the survey area and two transverse
lines to cover the whole survey area.
Final Report on Sub Bottom Profilling Survey
Off Goa, West Coast of India
For Mormugao Port Trust,Goa
Final report No: Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009
17
DBM GEOTECHNICS AND CONSTRUCTIONS PVT.LTD.MUMBAI
The sub-bottom profiler data, recorded at a sweep rate of 50 m sec, was used to examine the shallow subsurface stratigraphy. Penetration of the sub bottom profiler was achieved up to a depth of about 20 metres sub
seabed or upto to 1st seabed multiple to allow an accurate assessment of shallow geology within the
geophysical survey corridor. The limit of recording reached before the seabed multiple is encountered
effectively limiting usable data below this depth and obscuring further delineation of layers. Generally noise
free coherent data is recorded to the limit of recording.
All sedimentary properties defined in relevant sections below are based on assessment of the recorded
acoustic characteristics of the material along with interpreted sedimentary structures. Additionally, gravity core
sampling and other geotechnical information, appropriate reference to the echo sounder, side scan data sets
within the survey corridor was carried out as necessary.
The shallow sedimentary sequence within the surveyed area indicates formation of beach deposits. The
stratigraphic sequence within the survey area indicates primarily sands with minor proportions of silt / clay.
Unit -1 is the uppermost and parallel reflector unit identified within the surveyed corridor occurring all along the
survey area. Sediments pattern indicate an acoustically transparent veneer of surficial layer at places within
the corridor interpreted to comprise of predominantly unconsolidated silty clay. Based on the internal acoustics
character of the sediments and the sediment sampling [gravity coring], delineation of Unit-2 and Unit-3 has
been done.
In the middle of the surveyed area parallel bedded homogenous sediments of low to medium acoustic
impedance to the seismic energy formed rhythmically with the seabed changes are recorded and are
interpreted as fine silty clay overprinted by deposits of fine to medium sands. This layer occurs predominantly
in the northwest quadrant of the survey area and is designated as Unit-2. Average thickness of this Unit-2
sediment is about 0.8 metres.
Underlain by Unit-2 sediments is Unit-3 which is interpreted to comprise highly weathered bedrock (lateritic
and basaltic rocks) admixed with compact silty clay with density increasing with depth. This is the deepest
layer discernible from the records. Base of this layer is not discernible from the records due to strong masking
and also due to onset of 1st multiple obscuring further delineation of layers, if any, in shallow waters. This unit
is recorded all along the survey areas. From drop core sampling it is observed that this is highly weathered.
No anomalies associated with shallow gas were evident from the sub-bottom profiler survey records.
9.7
SHALLOW SOIL SAMPLING
Ten drop cores/grab samples were collected covering whole survey area. Visual analysis (colour & type of
soil) and shear strength parameters (with Torvane and Pocket Penetrometer) were carried out in-site on-board
the vessel as soon as the sample is recovered. Out of these 6 representative samples were sent to the
laboratory for further analysis. Their detailed on-board analysis is placed at Appendix C and laboratory
analysis at Appendix D
Final Report on Sub Bottom Profilling Survey
Off Goa, West Coast of India
For Mormugao Port Trust,Goa
Final report No: Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009
18
DBM GEOTECHNICS AND CONSTRUCTIONS PVT.LTD.MUMBAI
APPENDIX A
CHRONOLOGICAL SUMMARY OF EVENTS
Final Report on Sub Bottom Profilling Survey
Off Goa, West Coast of India
For Mormugao Port Trust,Goa
Final report No: Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009
19
DBM GEOTECHNICS AND CONSTRUCTIONS PVT.LTD.MUMBAI
APPENDIX C1
POSITIONING SYSTEM
Final Report on Sub Bottom Profilling Survey
Off Goa, West Coast of India
For Mormugao Port Trust,Goa
Final report No: Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009
20
DBM GEOTECHNICS AND CONSTRUCTIONS PVT.LTD.MUMBAI
CALIBRATION OF DGPS POSITIONING SYSTEM AT DBM WORKSHOP ROOF,MUMBAI
The DGPS system was calibrated at DBM office building station at Mumbai. The station is situated on the roof of
the DBM Workshop building,Mumbai. The DGPS beacon system was placed on the specified station and the
position was logged for a duration of 30 minutes between 1400 Hrs to 1430 Hrs on 14th Feb, 2009.The observed
co-ordinates were compared with the previous establish station in the following table.
OBSERVED CO-ORDINATES AT DBM WORKSHOP STATION
WGS 84, CM 75, ZONE 43
UTM CO-ORDINATES
TIME
EASTING (m)
NORTHING (m)
14:00
289 475.979
2111 284.143
14:02
289 472.535
2111 284.276
14:04
289 474.268
2111 284.411
14:06
289 475.316
2111284.030
14:08
289 474.105
2111 284.520
14:10
289 473.038
2111 284.241
14:12
289 474.268
2111 284.411
14:14
289 473.579
2111 284.526
14:16
289 472.877
2111 284.534
14:18
289 474.589
2111 284.324
14:20
289 474.355
2111 284.392
14:22
289 474.376
2111 284.486
14:24
289 474.567
2111 284.265
14:26
289 474.289
2111 284.234
14:28
289 473.935
2111 284.286
14:30
289 474.324
2111 284.328
MEAN
289 474.150
2111 284.275
Comparison between observed co-ordinates and previous establish station of office building station is as below.
Station: Marine office building
WGS 84, CM 69, Zone 42
EASTING
NORTHING
(m)
(m)
OBSERVED CO-ORDINATES in UTM
WORKSHOP BUILDING STATION
DIFFERENCE in UTM
289 474.150
289 473.925
0.235 m
Final Report on Sub Bottom Profilling Survey
Off Goa, West Coast of India
For Mormugao Port Trust,Goa
Final report No: Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009
20
2111 284.275
2111 284.128
0.147 m
DBM GEOTECHNICS AND CONSTRUCTIONS PVT.LTD.MUMBAI
APPENDIX D
OBSERVED TIDAL READINGS
Final Report on Sub Bottom Profilling Survey
Off Goa, West Coast of India
For Mormugao Port Trust,Goa
Final report No: Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009
20
DBM GEOTECHNICS AND CONSTRUCTIONS PVT.LTD.MUMBAI
APPENDIX E
ON-BOARD SOIL SAMPLES ANALYSIS
Final Report on Sub Bottom Profilling Survey
Off Goa, West Coast of India
For Mormugao Port Trust,Goa
Final report No: Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009
20
DBM GEOTECHNICS AND CONSTRUCTIONS PVT.LTD.MUMBAI
APPENDIX F
LABORATORY SOIL SAMPLE ANALYSIS
Final Report on Sub Bottom Profilling Survey
Off Goa, West Coast of India
For Mormugao Port Trust,Goa
Final report No: Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009
20
DBM GEOTECHNICS AND CONSTRUCTIONS PVT.LTD.MUMBAI
APPENDIX G
EXTRACTS FROM FIELD RECORDS
Final Report on Sub Bottom Profilling Survey
Off Goa, West Coast of India
For Mormugao Port Trust,Goa
Final report No: Job.no.2337 Finrep (Rev. 0) dt. 09/03/2009
20
DBM GEOTECHNICS AND CONSTRUCTIONS PVT.LTD.MUMBAI