HYDROGRAPHIC SURVEYS SPECIFICATIONS AND DELIVERABLES April 2017 U.S. Department of Commerce National Oceanic and Atmospheric Administration National Ocean Service Contents 1 Introduction ......................................................................................................................................1 1.1 Change Management ............................................................................................................................................. 1 1.2 Changes from March 2016 .................................................................................................................................... 2 1.3 Definitions ............................................................................................................................................................... 6 1.3.1 Hydrographer ................................................................................................................................................. 6 1.3.2 Navigable Area Survey .................................................................................................................................. 6 1.4 Pre-Survey Assessment ......................................................................................................................................... 8 1.5 Environmental Compliance .................................................................................................................................. 8 1.6 Dangers to Navigation ........................................................................................................................................... 9 1.6.1 Definition ......................................................................................................................................................... 9 1.6.2 Elevated Pipelines ............................................................................................................................................ 9 1.6.3 USACE Channel DTONs ............................................................................................................................. 10 1.6.4 DTON Submission ........................................................................................................................................ 10 1.6.5 Charted Feature Remove Request (Anti-DTON) ..................................................................................... 11 1.7 Non-DTON Seep and Pipeline Report .............................................................................................................. 11 2 Datums ............................................................................................................................................13 2.1 Time ....................................................................................................................................................................... 13 2.2 Horizontal Datum ................................................................................................................................................ 13 2.3 Vertical Datum ...................................................................................................................................................... 13 2.3.1 Charted Soundings and Heights ................................................................................................................. 13 2.3.2 Survey Platform Positioning (Control) ...................................................................................................... 13 3 Hydrographic Positioning .............................................................................................................14 3.1 GNSS Terminology .............................................................................................................................................. 14 3.2 Horizontal Control ............................................................................................................................................... 14 3.3 Vertical Control .................................................................................................................................................... 15 3.4 Differential GNSS Reference Stations (DGPS & ERS) .................................................................................... 15 3.5 Ellipsoid Referenced Survey Control ................................................................................................................. 15 3.5.1 ERS Planning and Operational Requirement .......................................................................................... 16 3.5.2 ERS GNSS Infrastructure ........................................................................................................................... 16 3.6 ERS Datum Transformation Requirements ...................................................................................................... 17 3.6.1 VDatum ........................................................................................................................................................ 17 3.6.2 Ellipsoidally-Referenced Zoned Tides (ERZT) ...................................................................................... 18 3.6.3 Constant Value Separation Model ............................................................................................................ 18 4 Tides and Water Levels Requirements .........................................................................................19 4.1 General Project Requirements and Scope ......................................................................................................... 20 4.1.1 Scope ............................................................................................................................................................. 20 4.1.2 Objectives ..................................................................................................................................................... 20 4.1.3 Planning and Preliminary Tidal Zoning .................................................................................................. 20 4.1.4 NOS Control Stations and Data Quality Monitoring ............................................................................. 21 4.1.5 General Data and Reference Datum Requirements ................................................................................ 21 4.1.6 Error Budget Considerations ..................................................................................................................... 22 4.2 Data Collection and Field Work ......................................................................................................................... 24 4.2.1 Water Level Station Requirements ............................................................................................................ 24 4.2.2 Water Level Measurement Systems and Data Transmissions ................................................................ 25 4.2.2.1 Bottom Mounted Pressure Gauge (BMPG) ...................................................................................... 27 4.2.2.2 GPS Tide Buoys ..................................................................................................................................... 28 4.2.3 Station Installation, Operation and Removal .......................................................................................... 28 4.2.4 Tide Staff ...................................................................................................................................................... 30 4.2.5 Bench Marks ................................................................................................................................................. 32 4.2.5.1 Number and Type of Bench Marks ..................................................................................................... 33 4.2.5.2 Digital Photographs of the Bench Marks ........................................................................................... 33 4.2.5.3 Obtaining and Recording of Positions of Stations, Data Collection Platform, Sensors, and Bench Marks Using a Handheld GPS Receiver .......................................................................................................... 34 4.2.6 Leveling ........................................................................................................................................................... 35 4.2.6.1 Leveling Frequency ................................................................................................................................ 35 4.2.6.2 Stability ................................................................................................................................................... 35 4.2.7 Water Level Station Documentation ......................................................................................................... 36 4.2.8 Additional Field Requirements .................................................................................................................. 36 4.2.9 Geodetic Connections and Datums Relationship ................................................................................... 37 4.3 Data Processing and Reduction .......................................................................................................................... 38 4.3.1 Data Quality Control..................................................................................................................................