Bench Mark Sheet for 8760595, BRETON ISLAND LA

Superseded Epoch

Large map location marker Station Location
Small red map location marker Published bench mark
Small blue map location marker Unpublished bench mark

Bench mark positions only appear on the map if their coordinates in the CO-OPS database are at the precision of degrees/minutes/seconds/and tenths of seconds. If the coordinates are less precise, the mark will not appear.

Printable version

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  7

                                                                                
Station ID: 8760595                         PUBLICATION DATE:  06/09/2003
Name:       BRETON ISLAND                                     
            LA
NOAA Chart: 11363                           Latitude:   29° 29.6' N (  29.49330)
USGS Quad:  BRETON ISLANDS                  Longitude:  89° 10.4' W ( -89.17330)


To reach the tidal bench marks from Venice, proceed by boat across the
Mississippi River, then NE on Baptiste Collette Bayou for 13 km (8 mi) to the
end of the channel markers, then NE across Breton Sound for 18 km (11 mi) to the
Kerr-McGee oil facility on Breton Island.  The bench marks are on the grounds of
the oil facility and in the marsh to the north.  The tide gage and staff were on
the west side and NW corner, respectively, of the T-shaped wooden dock.


                         T I D A L   B E N C H   M A R K S


                 PRIMARY BENCH MARK STAMPING:  0595 A 1980
                         DESIGNATION:          876 0595 A

MONUMENTATION:           Tidal Station disk                    VM#:         7089
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   29° 29.6' N (  29.49330)          LONGITUDE:  89° 10.4' W ( -89.17330)


The primary bench mark is a disk located in the marsh NE of the circular
bulkhead around the oil facility, 61 m (200 ft) NNE of Corps of Engineers (COE)
bench mark 876 0595 USE 1, 55 m (182 ft) NNE of the bulkhead around the oil
facility, 30 m (98 ft) north of the NE anchor pile of the radio tower guy wire
system, and 24 m (80 ft) west of the west shoreline of the bay inside the east
side of the island.  The bench mark is set 9 cm (0.3 ft) below ground level,
crimped to the top of a stainless steel rod driven 15.2 m (50 ft) to refusal,
and encased in a 4-inch PVC pipe.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  7

                                                                                
Station ID: 8760595                         PUBLICATION DATE:  06/09/2003
Name:       BRETON ISLAND                                     
            LA
NOAA Chart: 11363                           Latitude:   29° 29.6' N (  29.49330)
USGS Quad:  BRETON ISLANDS                  Longitude:  89° 10.4' W ( -89.17330)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  0595 B 1980
                         DESIGNATION:          876 0595 B

MONUMENTATION:           Tidal Station disk                    VM#:         7090
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   29° 29.6' N (  29.49330)          LONGITUDE:  89° 10.4' W ( -89.17330)


The bench mark is a disk located in the marsh, 117 m (385 ft) NNE of the west
radio tower guy wire anchor, 112 m (369 ft) north of COE bench mark 876 0595 USE
2, 110 m (360 ft) north of the circular bulkhead around the oil facility, 95 m
(311 ft) NNW of the NE radio tower guy wire anchor, 67 m (219 ft) NNW of bench
mark 0595 A 1980, and 18 m (58 ft) south of the shoreline of the small bay which
is north of the oil facility.  The bench mark is set 6 cm (0.2 ft) below ground
level, crimped to the top of a stainless steel rod driven 16.8 m (55 ft) to
refusal, and encased in a 4-inch PVC pipe.



                         BENCH MARK STAMPING:  0595 C 1980
                         DESIGNATION:          876 0595 C

MONUMENTATION:           Tidal Station disk                    VM#:         7091
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   29° 29.6' N (  29.49330)          LONGITUDE:  89° 10.4' W ( -89.17330)


The bench mark is a disk located in the marsh, 107 m (350 ft) WNW of the NW
radio tower guy wire anchor, 93 m (306 ft) NW of bench mark 876 0595 USE 2, 86 m
(281 ft) NNW of the circular bulkhead around the oil facility, 77 m (251 ft) SW
of bench mark 0595 B 1980, 43 m (140 ft) north of the west anchor pile of the
radio tower, and 18 m (59 ft) north of the NW end of the facility.  The bench
mark is set 9 cm (0.3 ft) below ground level, crimped to the top of a stainless
steel rod driven 18.3 m (60 ft) to refusal, and encased in a 4-inch PVC pipe.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  7

                                                                                
Station ID: 8760595                         PUBLICATION DATE:  06/09/2003
Name:       BRETON ISLAND                                     
            LA
NOAA Chart: 11363                           Latitude:   29° 29.6' N (  29.49330)
USGS Quad:  BRETON ISLANDS                  Longitude:  89° 10.4' W ( -89.17330)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  BRETON RM NO 2
                         DESIGNATION:          876 0595 BRETON RM 2

MONUMENTATION:           Reference Mark disk                   VM#:         7092
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:        
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID:        
LATITUDE:   29° 29.6' N (  29.49330)          LONGITUDE:  89° 10.4' W ( -89.17330)


The bench mark is a disk set on the west side of the oil facility near the NW
radio tower guy wire anchor, 5 m (17 ft) NW of the NW corner of a generator
house, and 1 m (2 ft) east of the bulkhead.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  7

                                                                                
Station ID: 8760595                         PUBLICATION DATE:  06/09/2003
Name:       BRETON ISLAND                                     
            LA
NOAA Chart: 11363                           Latitude:   29° 29.6' N (  29.49330)
USGS Quad:  BRETON ISLANDS                  Longitude:  89° 10.4' W ( -89.17330)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:   
                         DESIGNATION:          876 0595 USE 1
                         ALIAS:                NO STAMPING 1

MONUMENTATION:           Survey disk                           VM#:         7093
AGENCY:                  US Army Corps Of Engineers (USE)      IDB PID#:        
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID:        
LATITUDE:   29° 29.6' N (  29.49330)          LONGITUDE:  89° 10.4' W ( -89.17330)


The bench mark is a disk set in a concrete monument at the foot of the dock on
the east side of the oil facility, 20.27 m (66.5 ft) NE of the centerline of a
concrete ramp leading SSE from the island, 6.64 m (21.8 ft) south of the
centerline of the wood ramp leading east to the wooden dock, 5.64 m (18.5 ft)
ESE of the NE corner of the metal generator building, 1.52 m (5.0 ft) west of
the outside face of the circular bulkhead around the oil facility, and 0.15 m
(0.5 ft) above ground level.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  7

                                                                                
Station ID: 8760595                         PUBLICATION DATE:  06/09/2003
Name:       BRETON ISLAND                                     
            LA
NOAA Chart: 11363                           Latitude:   29° 29.6' N (  29.49330)
USGS Quad:  BRETON ISLANDS                  Longitude:  89° 10.4' W ( -89.17330)


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:   
                         DESIGNATION:          876 0595 USE 2
                         ALIAS:                NO STAMPING 2

MONUMENTATION:           Survey disk                           VM#:         7094
AGENCY:                  US Army Corps Of Engineers (USE)      IDB PID#:        
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID:        
LATITUDE:   29° 29.6' N (  29.49330)          LONGITUDE:  89° 10.4' W ( -89.17330)


The bench mark is a disk set on the north side of the oil facility, 40.08 m
(131.5 ft) SW of the NE guy wire post for the antenna tower on the west side of
the island, 28.59 m (93.8 ft) NE of the center of the concrete base of the
antenna tower, 4.15 m (13.6 ft) NE of the NW corner of the metal walkway along
the north side of the crew quarters, 2.32 m (7.6 ft) south of the outside face
of the circular bulkhead around the oil facility, and 0.21 m (0.7 ft) above
ground level.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  6 of  7

                                                                                
Station ID: 8760595                         PUBLICATION DATE:  06/09/2003
Name:       BRETON ISLAND                                     
            LA
NOAA Chart: 11363                           Latitude:   29° 29.6' N (  29.49330)
USGS Quad:  BRETON ISLANDS                  Longitude:  89° 10.4' W ( -89.17330)


                            T I D A L   D A T U M S 


Tidal datums at BRETON ISLAND based on:

     LENGTH OF SERIES:      6 MONTHS
     TIME PERIOD:           July 1981 - December 1981
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8747437 BAY WAVELAND YC, BAY ST. LOUIS


Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:

     MEAN HIGHER HIGH WATER                     MHHW   =  0.417
     MEAN HIGH WATER                            MHW    =  0.417
     MEAN SEA LEVEL                             MSL    =  0.218
     MEAN TIDE LEVEL                            MTL    =  0.210
     MEAN LOW WATER                             MLW    =  0.001
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     0595 A 1980                                 0.490    0.073
     0595 B 1980                                 0.445    0.028
     0595 C 1980                                 0.850    0.433
     BRETON RM NO 2                              1.878    1.461
     876 0595 USE 1                              2.218    1.801
     876 0595 USE 2                              2.161    1.744


                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  7 of  7

                                                                                
Station ID: 8760595                         PUBLICATION DATE:  06/09/2003
Name:       BRETON ISLAND                                     
            LA
NOAA Chart: 11363                           Latitude:   29° 29.6' N (  29.49330)
USGS Quad:  BRETON ISLANDS                  Longitude:  89° 10.4' W ( -89.17330)


                             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.

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