Superseded Bench Mark Sheet for 8770613, Morgans Point, Barbours Cut TX

Present Epoch

Printable version

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

                                                   PUBLICATION DATE:  01/14/2000
Station ID: 8770613                                SUPERCEDED DATE:   04/21/2003
Name:       MORGANS POINT, BARBOURS CUT                       
            TEXAS
NOAA Chart: 11328                                  Latitude:         29° 40.9' N
USGS Quad:  TEXAS CITY                             Longitude:        94° 59.1' W


To reach the tidal bench marks from the intersection of Texas State Highway 146
and W. Barbours Cut Boulevard in La Porte, proceed east on W. Barbours Cut
Boulevard for approximately 0.8 km (0.5 mi) to the point where W. Barbours Cut
Boulevard becomes E. Barbours Cut Boulevard, then continue east on E. Barbours
Cut Boulevard for 3.2 km (2.0 mi) to the Port of Houston Authority entrance
gates, then continue through the gates and bear left, crossing the railroad
tracks, and then proceed to the U-shaped concrete dock on the ship channel.  The
bench marks are located in the vicinity of the Port of Houston Authority
property.  The tide gage and staff are located on a small wooden dock on the
east side of the concrete dock.


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


                 PRIMARY BENCH MARK STAMPING:  0613 A 1980
                         DESIGNATION:          877 0613 A TIDAL

MONUMENTATION:           Tidal Station disk                        VM#:    11213
AGENCY:                  National Ocean Service                    PID#:  AW4858
SETTING CLASSIFICATION:  Stainless steel rod


The primary bench mark is a disk located 47 m (153 ft) SSE of the SE corner of a
U-shaped concrete pier on which the tide station is located, 16 m (52 ft) east
of the centerline of the paved road leading to the pier, 0.67 m (2.2 ft) SE of
the SW corner of the Port of Houston Authority Fire Station, and 0.34 m (1.1 ft)
south of the south face of the fire station.  The bench mark is 10 cm (0.3 ft)
below ground level, crimped to the top of a stainless steel rod driven 12.2 m
(40 ft) to refusal and encased in a 4-inch PVC pipe and concrete kickblock.



                         BENCH MARK STAMPING:  MORGAN PT 3 NO 3 1973
                         DESIGNATION:          MORGAN PT 3 RM 3

MONUMENTATION:           Reference Mark disk                       VM#:    11214
AGENCY:                  CGS                                       PID#:  AW1554
SETTING CLASSIFICATION:  Curb


The bench mark is a disk set on the top center of the east curb of the west
bridge to the Houston Port Authority Container Terminal Dock at Morgans Point,
10.88 m (35.7 ft) NE of Bench Mark MORGAN POINT 3 USE, and 9.91 m (32.5 ft)
north of the entrance to the west bridge of the dock.

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

                                                   PUBLICATION DATE:  01/14/2000
Station ID: 8770613                                SUPERCEDED DATE:   04/21/2003
Name:       MORGANS POINT, BARBOURS CUT                       
            TEXAS
NOAA Chart: 11328                                  Latitude:         29° 40.9' N
USGS Quad:  TEXAS CITY                             Longitude:        94° 59.1' W


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


                         BENCH MARK STAMPING:  MORGAN PT 3 USE 1973
                         DESIGNATION:          MORGAN PT 3

MONUMENTATION:           Triangulation Station disk                VM#:    11215
AGENCY:                  CGS                                       PID#:  AW1555
SETTING CLASSIFICATION:  Bridge abutment


The bench mark is a disk set in the south end of the west wing of the head wall
of the west bridge to the Houston Port Authority Container Terminal Dock, and 1
m (2 ft) higher than the ramp leading to the dock.



                         BENCH MARK STAMPING:  E 1201 1973
                         DESIGNATION:          E 1201

MONUMENTATION:           Bench Mark disk                           VM#:    11218
AGENCY:                  NGS                                       PID#:  AW1556
SETTING CLASSIFICATION:  Bridge abutment


The bench mark is a disk set in top of the east end of the south concrete
abutment of the most westerly bridge of the Houston Port Authority Container
Terminal Dock, 84 m (276 ft) NW of the centerline of Morgans Point-La Porte
Road, 0.37 m (1.2 ft) east of the SE corner of a concrete walkway, and 0.3 m (1
ft) above the bridge floor.

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

                                                   PUBLICATION DATE:  01/14/2000
Station ID: 8770613                                SUPERCEDED DATE:   04/21/2003
Name:       MORGANS POINT, BARBOURS CUT                       
            TEXAS
NOAA Chart: 11328                                  Latitude:         29° 40.9' N
USGS Quad:  TEXAS CITY                             Longitude:        94° 59.1' W


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


                         BENCH MARK STAMPING:  LUB 0613 E 1992
                         DESIGNATION:          877 0613 E

MONUMENTATION:           Survey disk                               VM#:    11221
AGENCY:                  Lamar Univ. Beaumont                      PID:         
SETTING CLASSIFICATION:  Stainless steel rod


The bench mark is a disk located on the east side of an asphalt parking area
near a chain link fence approximately 213 m (700 ft) SE of the gauge site, and 1
m (2 ft) west of the fence.  The bench mark is level with the asphalt, crimped
to the top of a stainless steel rod driven 15.2 m (50 ft) to refusal, and
encased in a 6-inch PVC pipe and concrete kickblock.



                         BENCH MARK STAMPING:  LUB 0613 F 1992
                         DESIGNATION:          877 0613 F

MONUMENTATION:           Survey disk                               VM#:    11222
AGENCY:                  Lamar Univ. Beaumont                      PID:         
SETTING CLASSIFICATION:  Stainless steel rod


The bench mark is a disk located on the east side of an asphalt parking area
just inside a chain link fence corner where the fence goes around a radio tower,
and 1 m (2 ft) west of the fence corner.  The bench mark is level with the
asphalt, crimped to the top of a stainless steel rod driven 15.2 m (50 ft) to
refusal, and encased in a 6-inch PVC pipe and concrete kickblock.

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

                                                   PUBLICATION DATE:  01/14/2000
Station ID: 8770613                                SUPERCEDED DATE:   04/21/2003
Name:       MORGANS POINT, BARBOURS CUT                       
            TEXAS
NOAA Chart: 11328                                  Latitude:         29° 40.9' N
USGS Quad:  TEXAS CITY                             Longitude:        94° 59.1' W


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


                         BENCH MARK STAMPING:  LUB 0613 G 1992
                         DESIGNATION:          877 0613 G

MONUMENTATION:           Survey disk                               VM#:    11223
AGENCY:                  Lamar Univ. Beaumont                      PID:         
SETTING CLASSIFICATION:  Stainless steel rod


The bench mark is a disk located on the outside of the SE corner of the fenced
asphalt parking area, and 1 m (2 ft) south of the chain link fence.  The bench
mark is at ground level, crimped to the top of a stainless steel rod driven 15.2
m (50 ft) to refusal, and encased in a 6-inch copper pipe.

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

                                                   PUBLICATION DATE:  01/14/2000
Station ID: 8770613                                SUPERCEDED DATE:   04/21/2003
Name:       MORGANS POINT, BARBOURS CUT                       
            TEXAS
NOAA Chart: 11328                                  Latitude:         29° 40.9' N
USGS Quad:  TEXAS CITY                             Longitude:        94° 59.1' W


                            T I D A L   D A T U M S 


Tidal datums at MORGANS POINT, BARBOURS CUT based on:

     LENGTH OF SERIES:      40 MONTHS
     TIME PERIOD:           April 1993 - July 1996
     TIDAL EPOCH:           1960-1978
     CONTROL TIDE STATION:  8771450 GALVESTON PIER 21, GALVESTON CHANNEL


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

     HIGHEST OBSERVED WATER LEVEL (04/25/1997)         =  1.309
     MEAN HIGHER HIGH WATER                     MHHW   =  0.396
     MEAN HIGH WATER                            MHW    =  0.370
     MEAN SEA LEVEL                             MSL    =  0.220
     MEAN TIDE LEVEL                            MTL    =  0.208
     MEAN LOW WATER                             MLW    =  0.046
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (01/19/1996)         = -1.056

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     0613 A 1980                                 5.383    5.013
     MORGAN PT 3 NO 3 1973                       4.374    4.004
     MORGAN PT 3 USE 1973                        4.366    3.996
     E 1201 1973                                 4.359    3.989
     LUB 0613 E 1992                             5.062    4.692
     LUB 0613 F 1992                             4.993    4.623
     LUB 0613 G 1992                             5.673    5.303


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

                                                   PUBLICATION DATE:  01/14/2000
Station ID: 8770613                                SUPERCEDED DATE:   04/21/2003
Name:       MORGANS POINT, BARBOURS CUT                       
            TEXAS
NOAA Chart: 11328                                  Latitude:         29° 40.9' N
USGS Quad:  TEXAS CITY                             Longitude:        94° 59.1' W


Foot Notes:

Galveston Bay, Texas has anomalous relative sea level trends compared to most
other geographic regions in the United States. This is due to a general
subsidence of land in this area, which has been occurring at a rapid rate.
Because of the magnitude of the sea level trends in these areas, NOAA has
adopted a procedure for computing accepted tidal datums for the National Water
Level Observation Network (NWLON) using the last several years of sea level data
rather than the 19 - year tidal epoch. The tide ranges are still based on the
1960 - 1978 National Tidal Datum Epoch (NTDE) and are applied to the 5 year
(1990 - 1994) mean tide level (MTL) to compute other tidal datums. The adoption
of this procedure was necessary to ensure that these tidal datums accurately
represent the existing stand of sea level.

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

                                                   PUBLICATION DATE:  01/14/2000
Station ID: 8770613                                SUPERCEDED DATE:   04/21/2003
Name:       MORGANS POINT, BARBOURS CUT                       
            TEXAS
NOAA Chart: 11328                                  Latitude:         29° 40.9' N
USGS Quad:  TEXAS CITY                             Longitude:        94° 59.1' W


                             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 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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