U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8760417 PUBLICATION DATE: 04/13/2018
Name: DEVON ENERGY FACILITY, NORTH PASS
LA
NOAA Chart: 11361 Latitude: 29° 12.0' N ( 29.20075)
USGS Quad: PASS A LOUTRE EAST Longitude: 89° 2.7' W ( -89.04447)
From the Venice, LA Boat Harbor, proceed 4.2 km (2.3 nm) NNE through a small
channel to the Mississippi River, turn right and proceed 16.7 km (9.0 nm) SSE
following the Mississippi River past Main Pass and Octave Pass to where the
river splits into 3 channels, turn left and follow the west most channel into
Pass A Loutre and continue 21.3 km (11.5 nm) east to the Devon Energy Facility
on the north bank of North Pass. The tide gauges were located on the platform
with the large metal tank. The bench marks are located along the main walkway
that runs parallel to the channel.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 0417 A 2008
DESIGNATION: 876 0417 A
MONUMENTATION: Tidal Station disk VM#: 18650
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete support beam OPUS PID#: BBBD74
LATITUDE: 29° 12.1' N ( 29.20170) LONGITUDE: 89° 2.7' W ( -89.04500)
The primary bench mark is set in a horizontal concrete support beam that
supports the main concrete walkway and a light pole, 53.10 m (174.2 ft) WSW from
bench mark 876 0417 B, 16.85 m (55.3 ft) WSW from the centerline of the steel
grate catwalk leading to the water tank platform, 2.06 m (6.8 ft) NNW from the
SE end of a concrete support beam, 1.99 m (6.5 ft) ENE from the outside corner
of the SW end of the main walkway, 0.70 m (2.3 ft) SSE from the SE edge of the
concrete walkway, 2.98 m (9.8 ft) above the ground, and 0.31 m (1.0 ft) below
the top of the walkway.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8760417 PUBLICATION DATE: 04/13/2018
Name: DEVON ENERGY FACILITY, NORTH PASS
LA
NOAA Chart: 11361 Latitude: 29° 12.0' N ( 29.20075)
USGS Quad: PASS A LOUTRE EAST Longitude: 89° 2.7' W ( -89.04447)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0147 B 2008
DESIGNATION: 876 0417 B
MONUMENTATION: Tidal Station disk VM#: 18651
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete supoprt beam OPUS PID:
LATITUDE: 29° 12.1' N ( 29.20170) LONGITUDE: 89° 2.7' W ( -89.04500)
The bench mark is set in a horizontal concrete support beam that supports the
main concrete walkway, 64.11 m (210.3 ft) WSW from bench mark 876 0417 C, 53.10
m (174.2 ft) ENE from bench mark 876 0417 A, 2.53 m (8.30 ft) NNW from the SE
end of the concrete support beam, 0.35 m (1.1 ft) SSE from the SE edge of the
concrete walkway, 2.98 m (9.8 ft) above the ground, and 0.31 m (1.0 ft) below
the top of the walkway.
BENCH MARK STAMPING: 0417 C 2008
DESIGNATION: 876 0417 C
MONUMENTATION: Tidal Station disk VM#: 18652
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete support beam OPUS PID:
LATITUDE: 29° 12.1' N ( 29.20170) LONGITUDE: 89° 2.6' W ( -89.04330)
The bench mark is set in a horizontal concrete support beam that supports the
main concrete walkway, 64.11 m (210.3 ft) ENE from bench mark 876 0417 B, 63.05
m (206.8 ft) WSW from bench mark 876 0417 D, 5.88 m (19.3 ft) ENE from the SE
face of a steel platform containing high voltage components, 2.53 m (8.30 ft)
NNW from the SE end of the concrete support beam, 0.35 m (1.1 ft) SSE from the
SE edge of the concrete walkway, 2.98 m (9.8 ft) above the ground, and 0.31 m
(1.0 ft) below the top of the walkway.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8760417 PUBLICATION DATE: 04/13/2018
Name: DEVON ENERGY FACILITY, NORTH PASS
LA
NOAA Chart: 11361 Latitude: 29° 12.0' N ( 29.20075)
USGS Quad: PASS A LOUTRE EAST Longitude: 89° 2.7' W ( -89.04447)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0417 D 2008
DESIGNATION: 876 0417 D
MONUMENTATION: Tidal Station disk VM#: 18653
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete support beam OPUS PID:
LATITUDE: 29° 12.0' N ( 29.20000) LONGITUDE: 89° 2.6' W ( -89.04330)
The bench mark is set in a horizontal concrete support beam that supports the
main concrete walkway and a light pole, 63.05 m (206.8 ft) ENE from bench mark
876 0417 C, 51.76 m (169.8 ft) WSW from bench mark 876 0417 E, 2.58 m (8.5 ft)
NNW from the SE end of the concrete support beam, 0.34 m (1.1 ft) SSE from the
SE edge of the concrete walkway, 2.98 m (9.8 ft) above the ground, and 0.31 m
(1.0 ft) below the top of the walkway.
BENCH MARK STAMPING: 0417 E 2008
DESIGNATION: 876 0417 E
MONUMENTATION: Tidal Station disk VM#: 18654
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete support beam OPUS PID:
LATITUDE: 29° 12.1' N ( 29.20170) LONGITUDE: 89° 2.6' W ( -89.04330)
The bench mark is set in a horizontal concrete support beam that supports the
main concrete walkway, 51.76 m (169.8 ft) ENE from bench mark 876 0417 D, 8.23 m
(27.0 ft) on a slope WSW from the SW edge of a lower wood walkway at the bottom
of the ramp, 3.36 m (11.0 ft) NNE from the northern most corner of a 2.92 m (9.6
ft) by 1.94 m (6.4 ft) metal electrical control building, 0.60 m (2.0 ft) SSE
from the NW end of the concrete support beam, 0.18 m (0.6 ft) NNW from the north
edge of the concrete walkway, 2.98 m (9.8 ft) above the ground, and 0.31 m (1.0
ft) below the top of the walkway.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8760417 PUBLICATION DATE: 04/13/2018
Name: DEVON ENERGY FACILITY, NORTH PASS
LA
NOAA Chart: 11361 Latitude: 29° 12.0' N ( 29.20075)
USGS Quad: PASS A LOUTRE EAST Longitude: 89° 2.7' W ( -89.04447)
T I D A L D A T U M S
Tidal datums at DEVON ENERGY FACILITY, NORTH PASS based on:
LENGTH OF SERIES: 7 MONTHS
TIME PERIOD: 5/08 - 8/08, 10/08, 12/08 - 1/09
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 = 0.362
MEAN HIGH WATER MHW = 0.360
MEAN TIDE LEVEL MTL = 0.182
MEAN SEA LEVEL MSL = 0.179
MEAN LOW WATER MLW = 0.004
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
0417 A 2008 2.829 2.469
0147 B 2008 2.921 2.561
0417 C 2008 2.859 2.499
0417 D 2008 2.837 2.477
0417 E 2008 2.779 2.419
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8760417 PUBLICATION DATE: 04/13/2018
Name: DEVON ENERGY FACILITY, NORTH PASS
LA
NOAA Chart: 11361 Latitude: 29° 12.0' N ( 29.20075)
USGS Quad: PASS A LOUTRE EAST Longitude: 89° 2.7' W ( -89.04447)
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.