U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8762223 PUBLICATION DATE: 04/16/2018
Name: EAST TIMBALIER ISLAND, TIMBALIER BAY
LA
NOAA Chart: 11357 Latitude: 29° 4.6' N ( 29.07670)
USGS Quad: CALUMET ISLAND Longitude: 90° 17.1' W ( -90.28500)
To reach the tidal bench marks from Leeville Bridge, proceed south on State
Highway 1 for 11.6 km (7.2 mi) to State Highway 3090, then turn right onto State
Highway 3090 and proceed SW for 5.1 km (3.2 mi) to a public boat ramp on the
left. From there, proceed by boat, following dredged canals east and then west
so as to pass under the State Highway 3090 bridge into Pass Fourchon, then
proceed north in Pass Fourchon and Bayou Lafourche for about 7.2 km (4.5 mi)
just past dual pipeline canals, then turn left into Havoline Canal and proceed
about 3.2 km (2.0 mi) to Timbalier Bay, then follow the channel markers in a
southwesterly direction to Channel Marker #2, then proceed south towards a radio
tower to Chevrons Gulf Timbalier Bay Camp. The bench marks are between the bay
and the rock break-water. The tide gage and staff were on the SE side of a small
timber boat dock south of the heliport.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 2223 C 1986
DESIGNATION: 876 2223 C TIDAL
MONUMENTATION: Tidal Station disk VM#: 7241
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 29° 4.6' N ( 29.07670) LONGITUDE: 90° 17.1' W ( -90.28500)
The primary bench mark is a disk located 62.18 m (204.0 ft) north of bench mark
2223 B 1986, 61 m (200 ft) east of an orange cap on a valve station located at
the SE corner of the Chevron facility, 6 m (20 ft) south of the high bank of a
small elongated pond located NE of the Chevron facility, and 0.49 m (1.6 ft) NNW
of a witness post. The bench mark is set 0.37 m (1.2 ft) above ground level,
crimped to the top of a stainless steel rod driven 20.7 m (68 ft) to refusal,
and encased in a 5-inch PVC pipe extending 0.61 m (2.0 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8762223 PUBLICATION DATE: 04/16/2018
Name: EAST TIMBALIER ISLAND, TIMBALIER BAY
LA
NOAA Chart: 11357 Latitude: 29° 4.6' N ( 29.07670)
USGS Quad: CALUMET ISLAND Longitude: 90° 17.1' W ( -90.28500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 2223 B 1986
DESIGNATION: 876 2223 B TIDAL
MONUMENTATION: Tidal Station disk VM#: 7240
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 29° 4.6' N ( 29.07670) LONGITUDE: 90° 17.1' W ( -90.28500)
The bench mark is a disk located 62.79 m (206.0 ft) east of bench mark 2223 A
1986, 31.82 m (104.4 ft) SE of a 1-inch galvanized pipe extending up from a
pipeline, 22.56 m (74.0 ft) north of the rock breakwater, and 0.46 m (1.5 ft) SE
of a witness post. The bench mark is set 0.46 m (1.5 ft) above ground level,
crimped to the top of a stainless steel rod driven 21.9 m (72 ft) to refusal,
and encased in a 5-inch PVC pipe extending 0.61 m (2.0 ft) above ground level.
BENCH MARK STAMPING: 2223 D 1987
DESIGNATION: 876 2223 D TIDAL
MONUMENTATION: Tidal Station disk VM#: 7242
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 29° 4.6' N ( 29.07670) LONGITUDE: 90° 17.1' W ( -90.28500)
The bench mark is a disk located SSE of the easternmost of three oil tanks, 52 m
(172 ft) west of bench mark 2223 A 1986, 29 m (95 ft) NNW of a plank and pile
fence parallel to the rock breakwater, 2 m (7 ft) ESE of the shoreline of the
bay, and 0.58 m (1.9 ft) south of a witness post. The bench mark is set 0.46 m
(1.5 ft) above ground level, crimped to the top of a a stainless steel rod
driven 23.9 m (78.5 ft) to substantial resistance, and encased in a PVC pipe
extending 1 m (2 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8762223 PUBLICATION DATE: 04/16/2018
Name: EAST TIMBALIER ISLAND, TIMBALIER BAY
LA
NOAA Chart: 11357 Latitude: 29° 4.6' N ( 29.07670)
USGS Quad: CALUMET ISLAND Longitude: 90° 17.1' W ( -90.28500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 2223 E 1987
DESIGNATION: 876 2223 E TIDAL
MONUMENTATION: Tidal Station disk VM#: 7243
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 29° 4.6' N ( 29.07670) LONGITUDE: 90° 17.1' W ( -90.28500)
The bench mark is a disk located WSW of bench mark 2223 D 1987, ESE of a radio
tower, 8.69 m (28.5 ft) ESE of a wooden walkway leading from the oil platform to
the rock breakwater, 2.56 m (8.4 ft) WNW of the westernmost of two black 6-inch
pipelines parallel to the walkway, and 2.50 m (8.2 ft) NW of a witness post.
The bench mark is set 0.46 m (1.5 ft) above ground level, crimped to the top of
a stainless steel rod driven 28.8 m (94.5 ft) to refusal, and encased in a PVC
pipe extending 0.61 m (2.0 ft) above ground level.
BENCH MARK STAMPING: 2223 A 1986
DESIGNATION: 876 2223 A TIDAL
MONUMENTATION: Tidal Station disk VM#: 17485
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 29° 4.6' N ( 29.07670) LONGITUDE: 90° 17.1' W ( -90.28500)
The bench mark is a disk located 91.44 m (300.0 ft) SE of the tide staff, 19.5 m
(64.0 ft) west of the NE end of a timber barrier located between the Chevron
Facility and the beach, 10.97 m (36.0 ft) NW of the 12th pile SW from the timber
barrier's NE end, and 0.46 m (1.5 ft) SE from the standard NOS witness post.
The bench mark is set 0.46 m (1.5 ft) above ground level, crimped to the top of
a stainless steel rod driven 21.9 m (72 ft) to refusal and encased in a 5-inch
PVC pipe driven 1.2 m (4.0 ft) beow ground and extending 0.61 m (2.0 ft) above
ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8762223 PUBLICATION DATE: 04/16/2018
Name: EAST TIMBALIER ISLAND, TIMBALIER BAY
LA
NOAA Chart: 11357 Latitude: 29° 4.6' N ( 29.07670)
USGS Quad: CALUMET ISLAND Longitude: 90° 17.1' W ( -90.28500)
T I D A L D A T U M S
Tidal datums at EAST TIMBALIER ISLAND, TIMBALIER BAY based on:
LENGTH OF SERIES: 1 YEAR
TIME PERIOD: January 1987 - December 1987
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:
HIGHEST OBSERVED WATER LEVEL (03/24/1987) = 0.611
MEAN HIGHER HIGH WATER MHHW = 0.404
MEAN HIGH WATER MHW = 0.394
MEAN SEA LEVEL MSL = 0.210
MEAN TIDE LEVEL MTL = 0.203
MEAN LOW WATER MLW = 0.012
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (02/24/1987) = -0.766
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
2223 C 1986 0.673 0.279
2223 B 1986 1.034 0.640
2223 D 1987 0.823 0.429
2223 E 1987 0.743 0.349
2223 A 1986 0.802 0.408
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8762223 PUBLICATION DATE: 04/16/2018
Name: EAST TIMBALIER ISLAND, TIMBALIER BAY
LA
NOAA Chart: 11357 Latitude: 29° 4.6' N ( 29.07670)
USGS Quad: CALUMET ISLAND Longitude: 90° 17.1' W ( -90.28500)
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.