Superseded Bench Mark Sheet for 8729747, SHIELD POINT, BLACKWATER RIVER

Present Epoch

Printable version

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  5

                                                   PUBLICATION DATE:  04/06/1984
Station ID: 8729747                                SUPERCEDED DATE:   04/21/2003
Name:       SHIELDS POINT, BLACKWATER BAY                     
            FLORIDA
NOAA Chart: 11382                                  Latitude:         30° 34.9' N
USGS Quad:  MILTON SOUTH                           Longitude:        87°  0.9' W


To reach the tidal bench marks proceed from the intersection of State Highway
191 and U.S. Highway 90 to Highway 191C, south for 2.6 miles (4.2 km), on State
Highway 191, SE on Highway 191C for 0.9 mile (1.4 km), to the overpass over
Interstate 10, then first left and follow the paved drive 0.5 mile (0.8 km), to
the Presley Residence.  The bench marks are located along Interstate 10 and the
Presley property and the tide gage and staff were located on a wooden dock
behind the Presley property.


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


                 PRIMARY BENCH MARK STAMPING:  NO 2 1976

MONUMENTATION:           Survey Disk                               VM#:    10220
AGENCY:                                                            PID#:  BG4533
SETTING CLASSIFICATION:  Copper-Clad Steel Rod


The bench mark is located 82 feet (25 m) south of the SE corner of a private
residence, 39 feet (12 m) east of the centerline of the driveway leading to the
residence, and 3 feet (1 m) NNE of a power pole with a witness sign at ground
level.  The bench mark is 0.25 feet (0.1 m) below ground level, crimped to a
copper-clad steel rod driven 24 feet (7 m) to refusal, and encased in 4-inch PVC
pipe and concrete kickblock.



                         BENCH MARK STAMPING:  NO 1 1976

MONUMENTATION:           Survey Disk                               VM#:    10219
AGENCY:                                                            PID#:  BG4534
SETTING CLASSIFICATION:  Copper-Clad Steel Rod


The bench mark is located 46.5 feet (14.2 m) east of the NE corner of the first
residence south of the tide gage site, 38.5 feet (11.7 m) west of a barbed wire
fence and 21.0 feet (6.4 m) south of an enclosed concrete pad. The bench mark is
at ground level, crimped to a copper-clad steel rod driven 23 feet (7 m) to
refusal in the SW corner of the a 10x15 foot (3x5 m), concrete pad.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  5

                                                   PUBLICATION DATE:  04/06/1984
Station ID: 8729747                                SUPERCEDED DATE:   04/21/2003
Name:       SHIELDS POINT, BLACKWATER BAY                     
            FLORIDA
NOAA Chart: 11382                                  Latitude:         30° 34.9' N
USGS Quad:  MILTON SOUTH                           Longitude:        87°  0.9' W


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


                         BENCH MARK STAMPING:  C165 RESET 1966

MONUMENTATION:           Survey Disk                               VM#:    10221
AGENCY:                                                            PID#:  BG0248
SETTING CLASSIFICATION:  Concrete Post


The bench mark is located near the Highway 191C overpass for Interstate 10, 28.0
feet (39.0 m), NE of the centerline of Highway 191C, 12.25 feet (37.3 m), NNE of
the NW end of the NE concrete bannister of the overpass, 29.5 feet (9.0 m), ENE
of a power line pole, 1.8 feet (0.5 m), SW of a metal witness post, and 1.2 feet
(0.4 m), NW of the Interstate 10 right-of-way fence.  The bench mark is set 1.0
foot, (0.3 m) below the ground in a concrete post.



                         BENCH MARK STAMPING:  RM NO 2

MONUMENTATION:           Survey Disk                               VM#:    10222
AGENCY:                                                            PID#:  BG3157
SETTING CLASSIFICATION:  Concrete Curb


The bench mark is located 12.6 feet (3.8 m) west of the centerline of the
Highway 191C overpass for Interstate 10, in the SW corner of the overpass and 6
feet (2 m) NE of a witness sign.  The bench mark is 0.8 foot (0.2 m) above
ground level and set flush in the curb.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  5

                                                   PUBLICATION DATE:  04/06/1984
Station ID: 8729747                                SUPERCEDED DATE:   04/21/2003
Name:       SHIELDS POINT, BLACKWATER BAY                     
            FLORIDA
NOAA Chart: 11382                                  Latitude:         30° 34.9' N
USGS Quad:  MILTON SOUTH                           Longitude:        87°  0.9' W


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


                         BENCH MARK STAMPING:  V 301

MONUMENTATION:           Survey Disk                               VM#:    10223
AGENCY:                                                            PID#:  BG0249
SETTING CLASSIFICATION:  Concrete Railing


The bench mark is located in the top of the SW concrete wingwall for the NW
abutment of the State Highway 191C overpass for Interstate 10, 13.4 feet (4.1 m)
SW of the centerline of State Highway 191C, 6.7 feet (2.0 m) SE of the NW end of
the wingwall, and 4.5 feet (1.4 m) NW of the NW end of the SW concrete
bannister.  The bench mark is set 3.0 feet (0.9 m) above the level of the
highway.



                         BENCH MARK STAMPING:  W 301

MONUMENTATION:           Survey Disk                               VM#:    10224
AGENCY:                                                            PID#:  BG0114
SETTING CLASSIFICATION:  Concrete Railing


The bench mark is located in the top of the SE end of the NE concrete wingwall
for the SE abutment of the Highway 191C overpass for Interstate 10, 14.5 feet
(4.4 m) NE of the centerline of the highway, and 4.7 feet (1.4 m) SE of the SE
end of the NE concrete bannister.  The bench mark is set 3.0 feet (0.9 m) above
the level of the highway.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  5

                                                   PUBLICATION DATE:  04/06/1984
Station ID: 8729747                                SUPERCEDED DATE:   04/21/2003
Name:       SHIELDS POINT, BLACKWATER BAY                     
            FLORIDA
NOAA Chart: 11382                                  Latitude:         30° 34.9' N
USGS Quad:  MILTON SOUTH                           Longitude:        87°  0.9' W


                            T I D A L   D A T U M S 


Tidal datums at SHIELDS POINT, BLACKWATER BAY based on:

     LENGTH OF SERIES:      10 MONTHS
     TIME PERIOD:           APRIL 1976-MAY 1977
     TIDAL EPOCH:           1960-1978
     CONTROL TIDE STATION:  8729840 PENSACOLA


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

     HIGHEST OBSERVED WATER LEVEL (03/28/1977)         =   2.84
     MEAN HIGHER HIGH WATER                     MHHW   =   1.55
     MEAN HIGH WATER                            MHW    =   1.47
     MEAN TIDE LEVEL                            MTL    =   0.80
   * NATIONAL GEODETIC VERTICAL DATUM           NGVD29 =   0.35
     MEAN LOW WATER                             MLW    =   0.12
     MEAN LOWER LOW WATER                       MLLW   =   0.00
     LOWEST  OBSERVED WATER LEVEL (12/21/1976)         =  -1.52

   * NGVD reference based on adjustment of 1971 and NOS levels of 7/11/77. 
North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In FEET above:

     Stamping or Designation                    MLLW        MHW

     NO 2 1976                                  15.24     13.77
     NO 1 1976                                  16.25     14.78
     C165 RESET 1966                            16.50     15.03
     RM NO 2                                    44.17     42.70
     V 301                                      46.23     44.76
     W 301                                      46.96     45.49


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

                                                   PUBLICATION DATE:  04/06/1984
Station ID: 8729747                                SUPERCEDED DATE:   04/21/2003
Name:       SHIELDS POINT, BLACKWATER BAY                     
            FLORIDA
NOAA Chart: 11382                                  Latitude:         30° 34.9' N
USGS Quad:  MILTON SOUTH                           Longitude:        87°  0.9' 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.

Return to Top
Products available at 8729747 SHIELD POINT, BLACKWATER RIVER,