Superseded Bench Mark Sheet for 8728942, CAPE SAN BLAS

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:  08/18/1988
Station ID: 8728942                                SUPERCEDED DATE:   04/21/2003
Name:       CAPE SAN BLAS, GULF OF MEXICO                     
            FLORIDA
NOAA Chart: 11389                                  Latitude:         29° 40.1' N
USGS Quad:  CAPE SAN BLAS                          Longitude:        85° 21.6' W


To reach the tidal bench marks from the Post Office at Port St. Joe, proceed 2.4
miles (3.9 km) south along U.S. Highway 98 to County Road C-30, then proceed on
County Road C-30 for 6.9 miles (11.1 km) to a paved road.  On the paved road
travel 2.8 miles (4.5 km) west to another paved road, then 0.6 miles (1.0 km) to
the Coast Guard Station on San Blas.  The bench marks are located around Coast
Guard Station. The tide gage and staff were on the pier at the shore by the dune
at the Coast Guard Station.


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


                 PRIMARY BENCH MARK STAMPING:  8942 A 1977

MONUMENTATION:           Survey Disk                               VM#:     9905
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Stainless Steel Rod


The bench mark is located 216 feet (66 m) south from the SE corner of a sewage
treatment plant, 155.8 feet (47.5 m) SE from the SE corner of the fence for the
Loran Antenna, and 86 feet (26 m) east from the SE anchor of the Loran Antenna. 
The bench mark is 0.2 foot (0.1 m) below ground level, crimped to a stainless
steel rod driven 37.3 feet (11.4 m) to refusal, and encased in PVC pipe and
concrete kickblock.



                         BENCH MARK STAMPING:  8942 B 1977

MONUMENTATION:           Survey Disk                               VM#:     9906
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Stainless Steel Rod


The bench mark is located 129 feet (39 m) from the SW corner of the fence for
Loran Antenna, 103.2 feet (31.5 m) SE from the SW anchor for the Loran Antenna,
and 2.2 feet (0.7 m) south from an abandoned fence post.  The bench mark is 0.3
foot (0.1 m) below ground level, crimped to a stainless steel rod driven 48 feet
(15 m) to refusal, and encased in PVC pipe and concrete kickblock.

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

                                                   PUBLICATION DATE:  08/18/1988
Station ID: 8728942                                SUPERCEDED DATE:   04/21/2003
Name:       CAPE SAN BLAS, GULF OF MEXICO                     
            FLORIDA
NOAA Chart: 11389                                  Latitude:         29° 40.1' N
USGS Quad:  CAPE SAN BLAS                          Longitude:        85° 21.6' W


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


                         BENCH MARK STAMPING:  8942 C 1977

MONUMENTATION:           Survey Disk                               VM#:     9907
AGENCY:                                                            PID#:  AS0925
SETTING CLASSIFICATION:  Stainless Steel Rod


The bench mark is located 503 feet (153 m) SE from the centerline of the Loran
Station Light Tower, 183 feet (56 m) NW from the Coast Guard Flag Pole, 89 feet
(27 m) NW from the western corner of 12 x 12 foot (4 x 4 m) building and
surrounded by a group of tall and scattered pine trees.  The bench mark is 0.2
foot (0.1 m) below ground level, crimped to a stainless steel rod driven 37.3
feet (11.4 m) to refusal, and encased in PVC pipe and concrete kickblock.



                         BENCH MARK STAMPING:  8942 D 1977

MONUMENTATION:           Survey Disk                               VM#:     9908
AGENCY:                                                            PID#:  AS0924
SETTING CLASSIFICATION:  Stainless Steel Rod


The bench mark is located 157.6 feet (48 m) east from Coast Guard Flag Pole,
82.1 feet (25.0 m) SW from the inside corner of wye formed by the entrance road
to the Loran Station and the access road to Air Force property, and 36.9 feet
(11.2 m) west from the pole marked 5-10583 acting as an anchor for a guy wire. 
The bench mark is 0.4 foot (0.1 m) below ground level, crimped to a stainless
steel rod driven 48 feet (15 m) to refusal, and encased in PVC pipe and concrete
kickblock.

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

                                                   PUBLICATION DATE:  08/18/1988
Station ID: 8728942                                SUPERCEDED DATE:   04/21/2003
Name:       CAPE SAN BLAS, GULF OF MEXICO                     
            FLORIDA
NOAA Chart: 11389                                  Latitude:         29° 40.1' N
USGS Quad:  CAPE SAN BLAS                          Longitude:        85° 21.6' W


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


                         BENCH MARK STAMPING:  A 339 1977

MONUMENTATION:           Survey Disk                               VM#:     9909
AGENCY:                                                            PID#:  AS0380
SETTING CLASSIFICATION:  Copper-clad Rod


The bench mark is located 345 feet (105 m) SW of the centerline of the road, 307
feet (94 m) west of the west corner of an elevated coast guard building, 251
feet (77 m) NW of the north corner of a wooden fence surrounding a Loran Antenna
Tower, 12 feet (4 m) south of the southwesternmost of 3 palm trees, 11 feet (3
m) north of a palm tree, and 1 foot (0.3 m) SE of a witness post .  The bench
mark is 1 foot (0.3 m) above ground level, crimped to a copper-clad rod driven
72 feet (22 m) to refusal, and encased in PVC pipe and concrete kickblock.

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

                                                   PUBLICATION DATE:  08/18/1988
Station ID: 8728942                                SUPERCEDED DATE:   04/21/2003
Name:       CAPE SAN BLAS, GULF OF MEXICO                     
            FLORIDA
NOAA Chart: 11389                                  Latitude:         29° 40.1' N
USGS Quad:  CAPE SAN BLAS                          Longitude:        85° 21.6' W


                            T I D A L   D A T U M S 


Tidal datums at CAPE SAN BLAS, GULF OF MEXICO based on:

     LENGTH OF SERIES:      7 MONTHS
     TIME PERIOD:           MARCH-SEPTEMBER 1978
     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 (01/25/1978)         =   2.95
     MEAN HIGHER HIGH WATER                     MHHW   =   1.39
     MEAN HIGH WATER                            MHW    =   1.37
     MEAN TIDE LEVEL                            MTL    =   0.68
     MEAN LOW WATER                             MLW    =   0.00
     MEAN LOWER LOW WATER                       MLLW   =   0.00
     LOWEST  OBSERVED WATER LEVEL (03/18/1978)         =  -1.63

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In FEET above:

     Stamping or Designation                    MLLW        MHW

     8942 A 1977                                 4.92      3.55
     8942 B 1977                                 7.64      6.27
     8942 C 1977                                 5.40      4.03
     8942 D 1977                                 6.23      4.86
     A 339 1977                                  5.89      4.52


Foot Notes:

Mean lower low water is equal to mean low water.

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

                                                   PUBLICATION DATE:  08/18/1988
Station ID: 8728942                                SUPERCEDED DATE:   04/21/2003
Name:       CAPE SAN BLAS, GULF OF MEXICO                     
            FLORIDA
NOAA Chart: 11389                                  Latitude:         29° 40.1' N
USGS Quad:  CAPE SAN BLAS                          Longitude:        85° 21.6' 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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