U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8763535 PUBLICATION DATE: 05/22/2014
Name: TEXAS GAS PLATFORM, CAILLOU BAY
LA
NOAA Chart: 11356 Latitude: 29° 10.5' N ( 29.17478)
USGS Quad: GRAND BAYOU DU LARGE Longitude: 90° 58.6' W ( -90.97644)
To reach this station by truck and boat, drive from the Post Office near the
cemetery in Theriot, LA, 17.3 km (10.8 mi) SSW on Bayou Dularge Road (Highway
315), launch the boat at the bait store and proceed south down the channel 13.7
km (8.3 mi) to the first large opening to the south, proceed SSW 6.1 km (3.8 mi)
across Lake Caillou to the mouth of a channel heading SW, follow the white 1"
PVC channel markers 6.7 km (4.2 mi) to the outlet of the channel on Caillou Bay,
proceed WSW 2.0 km (1.3 mi) to the platform which will be visible 4 km away on a
clear day. The tide shed was located on the upper platform and the orifices were
attached to the concrete pilings supporting the walkway nearest the dock. The
bench marks are located on the concrete deck and horizontal support beams of the
platform.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 3535 A 2008
DESIGNATION: 876 3535 A
MONUMENTATION: Tidal Station disk VM#: 18983
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete platform OPUS PID#: BBBF31
LATITUDE: 29° 10.5' N ( 29.17533) LONGITUDE: 90° 58.6' W ( -90.97675)
The primary bench mark is a disk set flush in the NW corner of the platform,
11.84 m (38.8 ft) north of the top of the stairs to the platform, 11.42 m (37.5
ft) NW of bench mark 876 3535 B, 0.88 m (2.9 ft) east of the west edge of the
platform, 0.76 m (2.5 ft) south of the north edge of the platform, and 1.12 (3.7
ft) below the top of the hand rail that surrounds the platform.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8763535 PUBLICATION DATE: 05/22/2014
Name: TEXAS GAS PLATFORM, CAILLOU BAY
LA
NOAA Chart: 11356 Latitude: 29° 10.5' N ( 29.17478)
USGS Quad: GRAND BAYOU DU LARGE Longitude: 90° 58.6' W ( -90.97644)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 3535 B 2008
DESIGNATION: 876 3535 B
MONUMENTATION: Tidal Station disk VM#: 18984
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete platform OPUS PID:
LATITUDE: 29° 10.5' N ( 29.17531) LONGITUDE: 90° 58.6' W ( -90.97667)
The bench mark is a disk set flush on the NE side of the platform, 10.09 m (33.1
ft) east of the west edge of the platform, 8.02 m (26.3 ft) NE of bench mark 876
3535 C, 3.74 m (12.3 ft) south of the north edge of the platform, 0.18 m (0.6
ft) west of the east edge of the platform, and 1.11 (3.6 ft) below the top of
the hand rail that surrounds the platform.
BENCH MARK STAMPING: 3535 C 2008
DESIGNATION: 876 3535 C
MONUMENTATION: Tidal Station disk VM#: 18985
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete platform OPUS PID:
LATITUDE: 29° 10.5' N ( 29.17525) LONGITUDE: 90° 58.6' W ( -90.97669)
The bench mark is a disk set flush in the SW corner of the platform, 37.68 m
(123.6 ft) north of bench mark 876 3535 D, 12.61 m (41.4 ft) south of the north
edge of the platform, 11.85 m (38.9 ft) south of bench mark 876 3535 A, 8.02 m
(26.3 ft) SW of bench mark 946 3535 B, 1.39 m (4.6 ft) south of the southern
most 0.39 diameter gas pipe, 0.48 m (1.6 ft) NE of the SW corner of the
platform, 0.23 m (0.8 ft) north of the south edge of the platform, 1.22 m (4.0
ft) below the top of the hand rail at the stairs upper landing, and 0.13 m (0.4
ft) below the top of the concrete bull rail that surrounds the top of the
platform.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8763535 PUBLICATION DATE: 05/22/2014
Name: TEXAS GAS PLATFORM, CAILLOU BAY
LA
NOAA Chart: 11356 Latitude: 29° 10.5' N ( 29.17478)
USGS Quad: GRAND BAYOU DU LARGE Longitude: 90° 58.6' W ( -90.97644)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 3535 D 2008
DESIGNATION: 876 3535 D
MONUMENTATION: Tidal Station disk VM#: 18986
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete pier OPUS PID:
LATITUDE: 29° 10.5' N ( 29.17494) LONGITUDE: 90° 58.6' W ( -90.97653)
The bench mark is a disk set flush in a horizontal concrete member for a metal
walkway, 35.28 m (115.7 ft) south of the base of the platform stairs, 18.38 m
(60.3 ft) north of bench mark 876 3535 E, 0.62 m (2.0 ft) SW of the NE edge of
the concrete support member, 1.33 m (4.4 ft) below the top of the walkway hand
rail, and 0.23 m (0.8 ft) below the walkway grating.
BENCH MARK STAMPING: 3535 E 2008
DESIGNATION: 876 3535 E
MONUMENTATION: Tidal Station disk VM#: 18987
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete pier OPUS PID:
LATITUDE: 29° 10.5' N ( 29.17478) LONGITUDE: 90° 58.6' W ( -90.97644)
The bench mark is a disk set flush in a horizontal concrete member for a metal
walkway, 54.80 m (179.8 ft) south of the north end of the metal walkway, 18.38 m
(60.3 ft) south of bench mark 876 3535 D, 4.57 m (15.0 ft) NNW of the SE cleat
on the floating dock, 3.93 m (12.9 ft) west of the east end of the floating
dock, 2.95 m (9.7 ft) east of the west end of the dock; 1.33 m (4.4 ft) below
the top of the walkway hand rail, and 0.23 m (0.8 ft) below the landing and
walkway grating.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8763535 PUBLICATION DATE: 05/22/2014
Name: TEXAS GAS PLATFORM, CAILLOU BAY
LA
NOAA Chart: 11356 Latitude: 29° 10.5' N ( 29.17478)
USGS Quad: GRAND BAYOU DU LARGE Longitude: 90° 58.6' W ( -90.97644)
T I D A L D A T U M S
Tidal datums at TEXAS GAS PLATFORM, CAILLOU BAY based on:
LENGTH OF SERIES: 1 YEAR
TIME PERIOD: June 2010 - May 2011
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8764227 LAWMA, AMERADA PASS
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (07/07/2010) = 1.037
MEAN HIGHER HIGH WATER MHHW = 0.493
MEAN HIGH WATER MHW = 0.460
MEAN SEA LEVEL MSL = 0.273
MEAN TIDE LEVEL MTL = 0.258
MEAN LOW WATER MLW = 0.057
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (04/05/2011) = -0.791
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
3535 A 2008 3.283 2.823
3535 B 2008 3.177 2.717
3535 C 2008 3.240 2.780
3535 D 2008 0.857 0.397
3535 E 2008 0.921 0.461
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8763535 PUBLICATION DATE: 05/22/2014
Name: TEXAS GAS PLATFORM, CAILLOU BAY
LA
NOAA Chart: 11356 Latitude: 29° 10.5' N ( 29.17478)
USGS Quad: GRAND BAYOU DU LARGE Longitude: 90° 58.6' W ( -90.97644)
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.