U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 4 Station ID: 8760943 PUBLICATION DATE: 04/26/2008 Name: PILOT STATION, SW PASS LOUISIANA NOAA Chart: 11361 Latitude: 28° 55.5' N USGS Quad: BURRWOOD BAYOU WEST Longitude: 89° 25.1' W To reach the tidal bench marks from Venice, proceed by boat south on the Mississippi River for 16.1 km (8.7 nm) to the Head of Passes, continue south down Southwest Pass for 29.3 km (15.8 nm) to the Associated Branch Pilots House. The bench marks are located on the river side of the Mississippi River along river bank. The tide gage and the staff are located on the SW corner of a pier near the water tower. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 0943A 1996 DESIGNATION: 876 0943 A MONUMENTATION: Flange-encased Rod VM#: 16856 AGENCY: National Ocean Service (NOS) PID: SETTING CLASSIFICATION: Stainless steel rod The primary bench mark is a flange-encased rod located on the river side of the Mississippi River levee, 153 m (503 ft) SSW of the intersection of stone riprap and a wooden pile dike, 9 m (31 ft) NW of stone riprap that protects the bank, and 5 m (16 ft) NNE of the NE corner of small wooden ramp that is attached to a walkway from Bar Pilot's House to the river bank. The bench mark is crimped to the top of a stainless steel rod driven 24.4 m (80 ft) to substantial resistance, and encased in a 5-inch PVC pipe with access cover. BENCH MARK STAMPING: 0943B 1996 DESIGNATION: 876 0943 B MONUMENTATION: Flange-encased Rod VM#: 16858 AGENCY: National Ocean Service (NOS) PID: SETTING CLASSIFICATION: Stainless steel rod The bench mark is flange-encased rod located on the river side of the Mississippi River levee, 113 m (370 ft) NW of ramp and conveyor belt in BP Oil Company Coke Dock, and 9 m (30 ft) from the base of the levee. The bench mark is set 0.8 m (2.5 ft) above the ground, crimped to the top of a 1/2-inch stainless steel rod driven 24.4 m (80 ft) to substantial resistance, and encased in a 4-inch white PVC pipe.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 4 Station ID: 8760943 PUBLICATION DATE: 04/26/2008 Name: PILOT STATION, SW PASS LOUISIANA NOAA Chart: 11361 Latitude: 28° 55.5' N USGS Quad: BURRWOOD BAYOU WEST Longitude: 89° 25.1' W T I D A L B E N C H M A R K S BENCH MARK STAMPING: 0943C 1996 DESIGNATION: 876 0943 C MONUMENTATION: Flange-encased Rod VM#: 16859 AGENCY: National Ocean Service (NOS) PID: SETTING CLASSIFICATION: Stainless steel rod The bench mark is a flange-encased rod located on the river side of the Mississippi River levee, 228 m (749 ft) NNE along river bank from a small wooden ramp attached to a walkway that leads to Bar Pilot's House in SW pass, 17 m (55 ft) west of stone riprap that protects the bank, and 15 m (49 ft) NNE of the intersection of the stone riprap and the wooden pile dike. The bench mark is set 0.6 m (2 ft) above the ground, crimped to the top of a 1/2-inch stainless steel rod driven 24.4 m (80 ft) to substantial resistance, and encased in a 5-inch white PVC pipe with access cover. BENCH MARK STAMPING: 0943E 1996 DESIGNATION: 876 0943 E MONUMENTATION: Flange-encased Rod VM#: 16861 AGENCY: National Ocean Service (NOS) PID: SETTING CLASSIFICATION: Stainless steel rod The bench mark is a flange-encased rod located on the river side of the Mississippi River levee, 220 m (723 ft) SSW of intersection of stone riprap and wooden pile dike, 67 m (220 ft) SSW along river bank from small wooden ramp attached to a walkway that leads to Bar Pilot's House in SW pass, 19 m (61 ft) west of stone riprap that protects the river bank. The mark is set 0.6 m (2 ft) above the ground, crimped to the top of a 1/2-inch stainless steel rod driven 24.4 m (80 ft) to substantial resistance, and encased in a 5-inch white PVC pipe with access cover.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 4 Station ID: 8760943 PUBLICATION DATE: 04/26/2008 Name: PILOT STATION, SW PASS LOUISIANA NOAA Chart: 11361 Latitude: 28° 55.5' N USGS Quad: BURRWOOD BAYOU WEST Longitude: 89° 25.1' W T I D A L D A T U M S Tidal datums at PILOT STATION, SW PASS based on: LENGTH OF SERIES: 18 MONTHS TIME PERIOD: September 2002 - February 2004 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 8761724 GRAND ISLE, EAST POINT Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: HIGHEST OBSERVED WATER LEVEL (09/26/2002) = 1.099 MEAN HIGHER HIGH WATER (MHHW) = 0.383 MEAN HIGH WATER (MHW) = 0.378 MEAN SEA LEVEL (MSL) = 0.194 MEAN TIDE LEVEL (MTL) = 0.192 MEAN LOW WATER (MLW) = 0.007 MEAN LOWER LOW WATER (MLLW) = 0.000 LOWEST OBSERVED WATER LEVEL (12/31/1997) = -0.596 National Geodetic Vertical Datum (NGVD 29) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 0943A 1996 0.553 0.175 0943B 1996 0.668 0.290 0943C 1996 0.665 0.287 0943E 1996 0.489 0.111 Foot Notes: Benchmarks 0943B 1996 and 0943C 1996 are based on one differential leveling connection and do not meet the quality control standards of the NOS. Therefore, caution should be used when deriving elevations for these marks.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 4 Station ID: 8760943 PUBLICATION DATE: 04/26/2008 Name: PILOT STATION, SW PASS LOUISIANA NOAA Chart: 11361 Latitude: 28° 55.5' N USGS Quad: BURRWOOD BAYOU WEST Longitude: 89° 25.1' W D E F I N I T I O N S Mean Sea Level (MSL) is a tidal datum determined over a 19-year National Tidal Datum Epoch. It pertains to local mean sea level and should not be confused with the fixed datums of North American Vertical Datum of 1988 (NAVD 88). NGVD 29 is a fixed datum adopted as a national standard geodetic reference for heights but is now considered superseded. NGVD 29 is sometimes referred to as Sea Level Datum of 1929 or as Mean Sea Level on some early issues of Geological Survey Topographic Quads. NGVD 29 was originally derived from a general adjustment of the first-order leveling networks of the U.S. and Canada after holding mean sea level observed at 26 long term tide stations as fixed. Numerous local and wide-spread adjustments have been made since establishment in 1929. Bench mark elevations relative to NGVD 29 are available from the National Geodetic Survey (NGS) data base via the World Wide Web at National Geodetic Survey. NAVD 88 is a fixed datum derived from a simultaneous, least squares, minimum constraint adjustment of Canadian/Mexican/United States leveling observations. Local mean sea level observed at Father Point/Rimouski, Canada was held fixed as the single initial constraint. NAVD 88 replaces NGVD 29 as the national standard geodetic reference for heights. Bench mark elevations relative to NAVD 88 are available from NGS through the World Wide Web at National Geodetic Survey. NGVD 29 and NAVD 88 are fixed geodetic datums whose elevation relationships to local MSL and other tidal datums may not be consistent from one location to another. The Vertical Mark Number (VM#) and PID# shown on the bench mark sheet are unique identifiers for bench marks in the tidal and geodetic databases, respectively. Each bench mark in either database has a single, unique VM# and/or PID# assigned. Where both VM# and PID# are indicated, both tidal and geodetic elevations are available for the bench mark listed. The NAVD 88 elevation is shown on the Elevations of Tidal Datums Table Referred to MLLW only when two or more of the bench marks listed have NAVD 88 elevations. The NAVD 88 elevation relationship shown in the table is derived from an average of several bench mark elevations relative to tide station datum. As a result of this averaging, NAVD 88 bench mark elevations computed indirectly from the tidal datums elevation table may differ slightly from NAVD 88 elevations listed for each bench mark in the NGS database.