Bench Mark Sheet for 8773037, Seadrift TX

Superseded Epoch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Small blue map location marker Unpublished bench mark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: 8773037                         PUBLICATION DATE:  07/25/2018
Name:       SEADRIFT, SAN ANTONIO BAY                         
            TX
NOAA Chart: 11315                           Latitude:   28° 24.4' N (  28.40690)
USGS Quad:  SEADRIFT, TX                    Longitude:  96° 42.7' W ( -96.71240)


To reach the tidal bench marks from the town of Seadrift, proceed on South Main
Street to the bay and continue into the boat basin and around to the west side
of the basin. The tide station is about 30 meters (98.4 ft) from the shore on a
platform installed by the Conrad Blucher Institute.


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


                 PRIMARY BENCH MARK STAMPING:  90031 A 1992
                         DESIGNATION:          877 3037 A
                         ALIAS:                3037 A 1992

MONUMENTATION:           Bench Mark disk                       VM#:        17545
AGENCY:                  Conrad Blucher Institute (CBI)        IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID#: BBFJ07
LATITUDE:   28° 24.4' N (  28.40739)          LONGITUDE:  96° 42.7' W ( -96.71239)


The primary bench mark is a brass disk located approximately 17.2 m (56.4 ft)
SSE of a wooden utility pole with two transformers mounted on it, 17.1 m (56.1
ft) SW of a post in the SW corner of a wooden bulkhead around some boat slips on
the west side of the boat ramp, 13.7 m (44.9 ft) WSW of a wooden utility pole
nearest the SW corner of a wooden bulkhead, crimped to a stainless steel rod
driven to an unspecified refusal and encased in a 6 inch PVC pipe with concrete
kickblock.

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

                                                                                
Station ID: 8773037                         PUBLICATION DATE:  07/25/2018
Name:       SEADRIFT, SAN ANTONIO BAY                         
            TX
NOAA Chart: 11315                           Latitude:   28° 24.4' N (  28.40690)
USGS Quad:  SEADRIFT, TX                    Longitude:  96° 42.7' W ( -96.71240)


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


                         BENCH MARK STAMPING:  90031 B 1992
                         DESIGNATION:          877 3037 B
                         ALIAS:                B 1992

MONUMENTATION:           Bench Mark disk                       VM#:        17546
AGENCY:                  Conrad Blucher Institute (CBI)        IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   28° 24.5' N (  28.40822)          LONGITUDE:  96° 42.7' W ( -96.71219)


The bench mark is a brass disk located on the south side of Bay Street, 91.4 m
(299.9 ft) north of bench mark 90031 A 1992, 8.6 m (28.2 ft) south of the south
edge of the pavement of Bay Street, 3.6 m (11.8 ft) NW of the northern most
wooden R/V utility hookup post in a north-south line of five such posts, 2.1 m
(6.9 ft) east of a power pole, 1.5 m (4.9 ft) south of an electric power line,
crimped to a stainless steel rod driven to unspecified depth and encased in a 6
inch PVC pipe with concrete kickblock.

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

                                                                                
Station ID: 8773037                         PUBLICATION DATE:  07/25/2018
Name:       SEADRIFT, SAN ANTONIO BAY                         
            TX
NOAA Chart: 11315                           Latitude:   28° 24.4' N (  28.40690)
USGS Quad:  SEADRIFT, TX                    Longitude:  96° 42.7' W ( -96.71240)


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


                         BENCH MARK STAMPING:  90031 C RESET
                         DESIGNATION:          877 3037 C RESET
                         ALIAS:                C 1992

MONUMENTATION:           Bench Mark disk                       VM#:        17547
AGENCY:                  Conrad Blucher Institute (CBI)        IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   28° 24.5' N (  28.40831)          LONGITUDE:  96° 42.8' W ( -96.71322)


The bench mark is a disk located on the south side of Bay Street, 91.4 m (299.9
ft) west of BM 90031 B 1992, 8.5 m (27.9 ft) from the NE corner of a public
restroom, 7.0 m (23.0 ft) south of the south edge of the pavement of Bay Street,
6.5 m (21.3 ft) SSE of the post of a weight limit sign on the south side of Bay
Street, 1.5 m (4.9 ft) south of the centerline of an electric power line,
crimped to a stainless steel rod driven to an unspecified depth  and encased in
a 6 inch PVC pipe with concrete kickblock.

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

                                                                                
Station ID: 8773037                         PUBLICATION DATE:  07/25/2018
Name:       SEADRIFT, SAN ANTONIO BAY                         
            TX
NOAA Chart: 11315                           Latitude:   28° 24.4' N (  28.40690)
USGS Quad:  SEADRIFT, TX                    Longitude:  96° 42.7' W ( -96.71240)


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


                         BENCH MARK STAMPING:  90031 D RESET
                         DESIGNATION:          877 3037 D RESET
                         ALIAS:                D 1992

MONUMENTATION:           Bench Mark disk                       VM#:        17548
AGENCY:                  Conrad Blucher Institute (CBI)        IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   28° 24.5' N (  28.40839)          LONGITUDE:  96° 42.9' W ( -96.71419)


The benck mark is a brass disk located on the south side of Bay Street, 1.5 m (5
ft) south of the centerline of an electric power line, crimped to a stainless
steel rod driven to refusal to an unspecified depth and encased in a 6 inch PVC
pipe with concrete kickblock.

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

                                                                                
Station ID: 8773037                         PUBLICATION DATE:  07/25/2018
Name:       SEADRIFT, SAN ANTONIO BAY                         
            TX
NOAA Chart: 11315                           Latitude:   28° 24.4' N (  28.40690)
USGS Quad:  SEADRIFT, TX                    Longitude:  96° 42.7' W ( -96.71240)


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


                         BENCH MARK STAMPING:  90031 E 1992
                         DESIGNATION:          877 3037 E
                         ALIAS:                E 1992

MONUMENTATION:           Bench Mark disk                       VM#:        17549
AGENCY:                  Conrad Blucher Institute (CBI)        IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   28° 24.5' N (  28.40850)          LONGITUDE:  96° 42.9' W ( -96.71519)


The bench mark is a brass disk located on the south side of Bay Street, 5.6 m
(18.4 ft) NNE of the SE corner of the top step of a set of five concrete steps
leading down a slope towards the Lions' Club Pavilion, 4.7 m (15.4 ft) south of
the south edge of the pavement of Bay Street, 4.2 m (13.8 ft) WNW of an upright
cross constructed of 8-inch steel pipe, 1.5 m (4.9 ft) south of the centerline
of an electric power line, crimped to a stainless steel rod driven to refusal to
an unspecified depth encased in a 6 inch PVC pipe with concrete kickblock.



                         BENCH MARK STAMPING:  3037 F 2012
                         DESIGNATION:          877 3037 F 2012

MONUMENTATION:           Tidal Station disk                    VM#:        22134
AGENCY:                  Conrad Blucher Institute (CBI)        IDB PID#:        
SETTING CLASSIFICATION:                                        OPUS PID:        
LATITUDE:   28° 24.4' N (  28.40747)          LONGITUDE:  96° 42.7' W ( -96.71222)


The bench mark is a disk set in concrete bulkhead of the southern most boat
slip, 71.6 m (235.14 ft) NNE of the tide station, 32.1 m (105.5 ft) SSW of the
NNW corner of northern most boat slip, 18.3 m (60.1 ft) ENE of benchmark 90031 A
1992.

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

                                                                                
Station ID: 8773037                         PUBLICATION DATE:  07/25/2018
Name:       SEADRIFT, SAN ANTONIO BAY                         
            TX
NOAA Chart: 11315                           Latitude:   28° 24.4' N (  28.40690)
USGS Quad:  SEADRIFT, TX                    Longitude:  96° 42.7' W ( -96.71240)


                            T I D A L   D A T U M S 


Tidal datums at SEADRIFT, SAN ANTONIO BAY based on:

     LENGTH OF SERIES:      8 MONTHS
     TIME PERIOD:           Oct 2016 - Jan 2017 and Mar 2017 - Jun 2017
     TIDAL EPOCH:           2002-2006
     CONTROL TIDE STATION:  8774770 ROCKPORT, ARANSAS BAY


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

     HIGHEST OBSERVED WATER LEVEL (08/26/2017)         =  1.824
     MEAN HIGHER HIGH WATER                     MHHW   =  0.116
     MEAN HIGH WATER                            MHW    =  0.113
     MEAN SEA LEVEL                             MSL    =  0.062
     MEAN TIDE LEVEL                            MTL    =  0.058
     MEAN LOW WATER                             MLW    =  0.003
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     North American Vertical Datum              NAVD88 = -0.267
     LOWEST  OBSERVED WATER LEVEL (01/16/2018)         = -0.497

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     90031 A 1992                                0.754    0.641
     90031 B 1992                                0.968    0.855
     90031 C RESET                               1.784    1.671
     90031 D RESET                               2.347    2.234
     90031 E 1992                                2.809    2.696
     3037 F 2012                                 1.073    0.960


Foot Notes:

Bench marks 90031 C 1992 and 90031 D 1992 were found to have been disturbed in
2012 and were stamped as reset at that time. New stampings are being verified
and will be updated in the above listing once confirmed.

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

                                                                                
Station ID: 8773037                         PUBLICATION DATE:  07/25/2018
Name:       SEADRIFT, SAN ANTONIO BAY                         
            TX
NOAA Chart: 11315                           Latitude:   28° 24.4' N (  28.40690)
USGS Quad:  SEADRIFT, TX                    Longitude:  96° 42.7' W ( -96.71240)


                             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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