U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 6
Station ID: 8760781 PUBLICATION DATE: 04/13/2018
Name: SHELL OIL, EAST BAY
LA
NOAA Chart: 11361 Latitude: 29° 3.2' N ( 29.05330)
USGS Quad: DIXON BAY Longitude: 89° 18.3' W ( -89.30500)
To reach the tidal bench marks from Venice, proceed by boat south on the
Mississippi River for 16.9 km (10.5 statute mi) to the Head of Passes, then
proceed on Southwest Pass for 13 km (8 statute mi) to the Shell Oil Company East
Bay Control Facilities (Shell Oil Facility) located on the east side of
Southwest Pass. The bench marks are located on the Shell Oil Facility grounds.
The tide station was located on the eastern side of the Shell Oil Facility
compound in the vicinity of the Fire Pump building.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 876 0783 C 1985
DESIGNATION: 876 0783 C TIDAL
MONUMENTATION: Tidal Station disk VM#: 7108
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete platform OPUS PID:
LATITUDE: 29° 3.2' N ( 29.05330) LONGITUDE: 89° 18.3' W ( -89.30500)
The primary bench mark is a disk set flush in a concrete platform in the
vicinity of the Fire Pump building, 5.91 m (19.4 ft) SW of the east corner of
the platform, 1.71 m (5.6 ft) NW of the south corner of the platform, and 0.49 m
(1.6 ft) NE of the SW face of the platform.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 8760781 PUBLICATION DATE: 04/13/2018
Name: SHELL OIL, EAST BAY
LA
NOAA Chart: 11361 Latitude: 29° 3.2' N ( 29.05330)
USGS Quad: DIXON BAY Longitude: 89° 18.3' W ( -89.30500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: TOWER 13 1976
DESIGNATION: BM TOWER 13 USE
MONUMENTATION: Bench Mark disk VM#: 7105
AGENCY: US Army Corps of Engineers (USE) IDB PID#: AT0146
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 29° 3.5' N ( 29.05830) LONGITUDE: 89° 18.4' W ( -89.30670)
The bench mark is a disk located under wooden Tower #13, 93.12 m (305.5 ft) NNE
of a vertical valve of the 8-inch Tennessee Gas pipe line, 73.76 m (242.0 ft)
NNW of the NW corner of the 2 m (5 ft) square concrete base of the filter tank
at the sewage plant, and 1.83 m (6.0 ft) south of the north leg of the tower.
The bench mark is set 1.10 m (3.6 ft) above the ground, crimped to the top of a
copper-clad steel rod driven to an unspecified depth, and encased in a 4-inch
PVC pipe.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 8760781 PUBLICATION DATE: 04/13/2018
Name: SHELL OIL, EAST BAY
LA
NOAA Chart: 11361 Latitude: 29° 3.2' N ( 29.05330)
USGS Quad: DIXON BAY Longitude: 89° 18.3' W ( -89.30500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: X280 RESET 1976
DESIGNATION: X 280 USE RESET 1976
MONUMENTATION: Bench Mark disk VM#: 7106
AGENCY: US Army Corps of Engineers (USE) IDB PID#: AT0148
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 29° 2.9' N ( 29.04830) LONGITUDE: 89° 18.8' W ( -89.31330)
The bench mark is a disk located in the vicinity of Tower #14, 130 m (426 ft) SW
of the west corner of the west piling of Old Cognac Separator platform, 70 m
(231 ft) WNW of 4-5 blowout tank, and 2.13 m (7.0 ft) south of the north leg of
Tower #14. The bench mark is set 0.52 m (1.7 ft) above the ground, crimped to
the top of a copper-clad steel rod driven to an unspecified depth, and encased
in a 4-inch PVC pipe.
BENCH MARK STAMPING: 876 0783 B 1985
DESIGNATION: 876 0783 B TIDAL
MONUMENTATION: Tidal Station disk VM#: 7107
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete pier OPUS PID:
LATITUDE: 29° 3.2' N ( 29.05330) LONGITUDE: 89° 18.3' W ( -89.30500)
The bench mark is a disk set flush in the top of the concrete loading pier cell
#3 (second cell north of walkway), 2.62 m (8.6 ft) NW of the center of the
bottom step leading to the cell top, 2.19 m (7.2 ft) east of a cleat, and 0.46 m
(1.5 ft) south of the north face of the cell.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 8760781 PUBLICATION DATE: 04/13/2018
Name: SHELL OIL, EAST BAY
LA
NOAA Chart: 11361 Latitude: 29° 3.2' N ( 29.05330)
USGS Quad: DIXON BAY Longitude: 89° 18.3' W ( -89.30500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 876 0783 D 1985
DESIGNATION: 876 0783 D TIDAL
MONUMENTATION: Tidal Station disk VM#: 7109
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete foundation OPUS PID:
LATITUDE: 29° 3.2' N ( 29.05330) LONGITUDE: 89° 18.3' W ( -89.30500)
The bench mark is a disk set flush in the concrete foundation on the north side
of fuel tank #F94635, 25.30 m (83.0 ft) ESE of the centerline of a shell road
running parallel to the river, 14.72 m (48.3 ft) west of the west corner of the
steel pump platform, 2.74 m (9.0 ft) WNW of a 4-inch pipe going into the base of
the tank, and 0.3 m (1.0 ft) above the ground.
BENCH MARK STAMPING: 876 0783 E 1985
DESIGNATION: 876 0783 E TIDAL
MONUMENTATION: Tidal Station disk VM#: 7110
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 29° 3.2' N ( 29.05330) LONGITUDE: 89° 18.3' W ( -89.30500)
The bench mark is a disk located approximately 152 m (500 ft) south of bench
mark 876 0783 A 1985, 106 m (347 ft) north of a 3 m (10 ft) high pole supporting
electrical boxes, 62.18 m (204.0 ft) south of a 10-inch vertical valve on the
Tennessee Gas pipe line, and 59.74 m (196.0 ft) NW of the NW column supporting
cooler #6. The bench mark is set 0.37 m (1.2 ft) above the ground, crimped to
the top of a stainless steel rod driven 14.6 m (48 ft), and encased in a 6-inch
PVC pipe.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 8760781 PUBLICATION DATE: 04/13/2018
Name: SHELL OIL, EAST BAY
LA
NOAA Chart: 11361 Latitude: 29° 3.2' N ( 29.05330)
USGS Quad: DIXON BAY Longitude: 89° 18.3' W ( -89.30500)
T I D A L D A T U M S
Tidal datums at SHELL OIL, EAST BAY based on:
LENGTH OF SERIES: 9 MONTHS
TIME PERIOD: 2/85 - 9/85, 11/85
TIDAL EPOCH: 2012-2016
CONTROL TIDE STATION: 8761724 GRAND ISLE, EAST POINT
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 0.403
MEAN HIGH WATER MHW = 0.398
MEAN TIDE LEVEL MTL = 0.203
MEAN SEA LEVEL MSL = 0.200
MEAN LOW WATER MLW = 0.009
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
876 0783 C 1985 1.839 1.441
TOWER 13 1976 2.161 1.763
X280 RESET 1976 1.509 1.111
876 0783 B 1985 0.791 0.393
876 0783 D 1985 0.408 0.010
876 0783 E 1985 1.620 1.222
Foot Notes:
Benchmarks 876 0783 E 1985 and X280 RESET 1976 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 6 of 6
Station ID: 8760781 PUBLICATION DATE: 04/13/2018
Name: SHELL OIL, EAST BAY
LA
NOAA Chart: 11361 Latitude: 29° 3.2' N ( 29.05330)
USGS Quad: DIXON BAY Longitude: 89° 18.3' W ( -89.30500)
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 (NAVD88).
NAVD88 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. NAVD88 replaces NGVD29 as the national
standard geodetic reference for heights. Bench mark elevations relative to
NAVD88 are available from NGS through the World Wide Web at
National Geodetic Survey.
NGVD29 is a fixed datum adopted as a national standard geodetic reference for
heights but is now considered superseded. NGVD29 is sometimes referred to as
Sea Level Datum of 1929 or as Mean Sea Level on some early issues of Geological
Survey Topographic Quads. NGVD29 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 NGVD29 are available from the National
Geodetic Survey (NGS) data base via the World Wide Web at
National Geodetic Survey.
NAVD88 and NGVD29 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 NGS's Integrated Data Base (IDB PID)
provides geodetic datum based on traditionally leveled and bluebooked ties to
the National Spatial Reference System(NSRS) https://www.ngs.noaa.gov/datasheets/.
The NGS Online Positioning User Service (OPUS PID) provides geodetic datum based
on GPS position & tie it to the NSRS https://www.ngs.noaa.gov/OPUS/.
The NAVD88 elevation is shown on the Elevations of Tidal Datums Table Referred
to MLLW only when two or more of the bench marks listed have NAVD88 elevations.
The NAVD88 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, NAVD88 bench mark elevations computed indirectly from the tidal
datums elevation table may differ slightly from NAVD88 elevations listed for
each bench mark in the NGS database.