Cameron_Creole_Freshwater_Intro_(CS-49)_Mag_Survey_Report.pdf

Survey Report Page i Cameron-Creole Freshwater Introduction May, 2013

CAMERON-CREOLE FRESHWATER

INTRODUCTION PROJECT

PROJECT NO. CS-49

SURVEY REPORT

PREPARED FOR:

MAY 2, 2013

SUBMITTED BY:

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CAMERON-CREOLE FRESHWATER

INTRODUCTION PROJECT

PROJECT NO. BA-125

SURVEY REPORT

Prepared for: U.S.D.A.

Natural Resources Conservation Service 3737 Government St.

Alexandria, LA 71302

Submitted By: T. Baker Smith, LLC 412 S. Van Ave.

Houma, LA 70363

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CAMERON-CREOLE FRESHWATER INTRODUCTION PROJECT

PROJECT NO. CS-49

SURVEY REPORT

TABLE OF CONTENTS

1.0 INTRODUCTION

2.0 PROJECT OVERVIEW

3.0 DATA COLLECTION SUMMARY

3.1 MAGNETOMETER SURVEYS

3.2 PIPELINE INVESTIGATION SURVEYS

4.0 METHODOLOGY

4.1 SURVEY CONTROL AND DATUM INFORMATION

4.2 GEOPHYSICAL SURVEYS

4.3 PIPELINE INVESTIGATION SURVEYS

LIST OF APPENDICES

APPENDIX 1 --- Survey Benchmark Datasheet

Digital Appendix

Project drawings (PDF format) Survey point data (CSV format) Survey Field Notes (PDF Format)

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SURVEY REPORT

CAMERON-CREOLE FRESHWATER

INTRODUCTION PROJECT

PROJECT NO. CS-49

1.0 INTRODUCTION

The purpose of the data collection tasks summarized in this report is to provide critical support information for planning and design of the Cameron-Creole Freshwater

Introduction Project (CS-49). The services provided under this task order involved geophysical field data collection and pipeline investigation, related data processing, and the organization of all data into a workable format for design purposes.

2.0 PROJECT OVERVIEW

The Cameron-Creole Freshwater Introduction Project is an authorized Project

Priority List 18 Coastal Wetlands Planning, Protection, and Restoration Act (CWPPRA)

Project. The project is sponsored by the Natural Resources Conservation Service

(NRCS), in cooperation with the Louisiana Coastal Protection and Restoration Authority

(CPRA). The primary objective of this project is to introduce fresh water from the Gulf

Intracoastal Waterway (GIWW) into the marshes to the south, construct approximately

65,000 linear feet of earthen terraces to reduce erosion from wind driven waves. The site is located immediately southwest of the intersection of the GIWW and Louisiana Hwy 27 in Cameron Parish.

3.0 DATA COLLECTION SUMMARY

During the period of March 26-28 and April 18-19 2013, T. Baker Smith, LLC

(TBS) collected field data throughout the project area. This data collection task consisted of geophysical surveys and pipeline investigations along the survey transects provided by

NRCS in the proposed project area. Geophysical data and the pipeline investigations were collected by a three-man survey crew aboard an airboat.

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3.1 MAGNETOMETER SURVEY

Magnetometer surveys were performed in the proposed project area to determine the location of any possible oil and gas pipelines and other metallic obstructions. The survey was performed using a 15’ airboat and a proton magnetometer. The magnetometer transects were spaced at approximately 500’ intervals throughout the project area. A total of 54 magnetic anomalies were detected during this survey. Some areas within the project site were unable to be run with the proton magnetometer due to high levees, spoil banks and very thick vegetation. These particular sections were investigated by the field crew with a gradiometer in order to detect any metallic obstructions.

3.2 PIPELINE INVESTIGATION SURVEY

All magnetic anomalies were investigated using a gradiometer and water jet probe to determine the possible existence of pipelines. A minimum of two circles were run with the gradiometer around each target, one with a 25’ radius and the other with a 50’ radius. Based on this investigation, no pipelines were found in the survey area. An overhead transmission line runs north and south through the west side of the project area.

This transmission line produced some abnormally large magnetic anomalies. There is also an overhead power line that runs parallel to the GIWW on the north end of the project area. Point 202, called out on page 3 of 5 of the plans and shown in the

“Miscellaneous Objects” table, is an area with a strong magnetometer reading. This area is believed to contain metal debris because a solid probe hit could not be obtained.

Based on oil/gas well positions obtained from the LDNR database, 3 plugged and abandoned wells were identified within the survey area. Two of these wells appear to have been previously accessed by land. There were no significant magnetic anomalies around these two positions; however, they are still identified as “Areas of Avoidance” for mechanical dredging operations. One well position did fall within the general region of magnetic anomalies found at the end of the location canal running north and south within the survey area. Field personnel were able to detect an unknown object in the probing

Survey Report Page 3 investigation. This point is called out as point 203 on page 4 of 5 of the plans and shown in the “Miscellaneous Objects” table. These investigations indicate a probable abandoned well casing or well pad at this location. Based on the correlation between the approximate database positions and the positions of strong magnetic anomalies along with the probing investigation, the “keyway” portion of this location canal has been identified as an “Area of Avoidance” for mechanical dredging operations.

4.0 METHODOLOGY

4.1 SURVEY CONTROL AND DATUM INFORMATION

The primary horizontal and vertical survey control used for all data collection on this project was Benchmark “CS11B-SM-02”, stamped “Sweet Lake”. The benchmark is part of LDNR’s secondary GPS network. The horizontal datum for all survey data collected is Louisiana State Plane, South Zone (1702), NAD 83, in U.S. Survey feet. The vertical datum for all data is NAVD 88 (Geoid 99), in U.S. Survey feet. Published data for the benchmarks can be seen in Appendix 1.

4.2 GEOPHYSICAL SURVEYS

Geophysical instruments used during this survey consisted of a Marine Magnetics

SeaSPY marine proton magnetometer. Horizontal positioning of the survey vessel was accomplished using HyPack® navigation software with a Trimble R8 GNSS (RTK) global positioning receiver. Horizontal accuracy of this positioning as stated by the manufacturer is 2-3 centimeters. The magnetometer sensor was deployed 50 feet behind the positioning antenna. The magnetometer sensor was attached to a buoyant PVC sled and towed behind the Airboat (see Figure 1). This method allows the operator to survey continuously through both open water and low-elevation marsh. The magnetometer sensor was set at .1sec/gamma.

All magnetometer data was digitally recorded by an onboard laptop computer using the SeaSPY interface linked with the HYPACK MAX survey navigation software mentioned above. The magnetic data was processed in Hypack to obtain the exact

Survey Report Page 4 position, signature type, and strength of each anomaly. The Hypack processing software allows the user to view the magnetic data as actual magnetic field values along a continuous line. The user is able to easily pinpoint anomalies as deflections from the normal magnetic field of 47,700 and note the position based on the center of the signature. Each magnetic anomaly is interpreted based on its size, signature type, and actual field observations.

Figure 1. Proton magnetometer sensor and PVC sled being towed behind Airboat.

4.3 PIPELINE INVESTIGATION SURVEYS

Pipeline investigation surveys were performed using a standard three-man survey crew, accessing the survey area by airboat. A Trimble model R8 GNSS GPS RTK unit was used to collect the topographic field data. The manufacturer’s stated accuracy of this unit is 2-3 cm horizontal, and 3-4 cm vertical. All RTK GPS Survey information was stored digitally using a Trimble TSC-2 Data Collector.

Topographic survey data was downloaded from the Trimble TSC-2 Data

Collector into the Trimble Business Center software for processing. This software allows

Survey Report Page 5 for QA/QC of GPS data, and was used to check for instrument setup errors, antenna height errors, and other errors. These points were then exported and entered into

AutoCAD Civil 3D for further processing. The processed survey data was also exported to one complete digital text file containing point numbers, X, Y, Z coordinates, and point descriptions using the DOTD survey feature code list.

Survey Report

APPENDIX 1

Survey Benchmark Data Sheets