Superseded Bench Mark Sheet for 8726573, GADSDEN POINT, TAMPA BAY FL

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:  09/24/1985
Station ID: 8726573                                SUPERCEDED DATE:   04/21/2003
Name:       GADSDEN POINT, TAMPA BAY                          
            FLORIDA
NOAA Chart: 11412                                  Latitude:         27° 49.3' N
USGS Quad:  GIBSONTON                              Longitude:        82° 29.1' W


To reach the tidal bench marks in Tampa, proceed to MacDill Air Force Base.  The
bench marks are located along Marina Drive.  The tide gage and staff were
located on the MacDill Air Force Base Marina pier.


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


                 PRIMARY BENCH MARK STAMPING:  NO 4 1975

MONUMENTATION:           Survey Disk                               VM#:     6573
AGENCY:                                                            PID#:  AG7535
SETTING CLASSIFICATION:  Concrete Foundation


The bench mark is near the intersection of Marina Drive and South Shore Road,
set flush in the NE corner of a concrete manhole collar, 290 feet (88 m) SE of
Bench Mark Bunker 2 1956, 65 feet (20 m) NE of a 30 MPH sign, and 25.6 feet (7.8
m) east of the centerline of Marina Drive.



                         BENCH MARK STAMPING:  NO 2 1975

MONUMENTATION:           Survey Disk                               VM#:     6571
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Copper-clad Steel Rod


The bench mark is 174 feet (53 m) north of the NE corner of the Snack Bar
(Building 692), 26.2 feet (8.0 m) east of a fire hydrant, 13.6 feet (4.1 m)
north of the centerline of Marina Drive, and 1.6 feet (0.5 m) west of a witness
sign.  The bench mark is level with the ground, crimped to a copper-clad steel
rod driven to refusal, and encased in a PVC pipe and concrete kickblock.

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

                                                   PUBLICATION DATE:  09/24/1985
Station ID: 8726573                                SUPERCEDED DATE:   04/21/2003
Name:       GADSDEN POINT, TAMPA BAY                          
            FLORIDA
NOAA Chart: 11412                                  Latitude:         27° 49.3' N
USGS Quad:  GIBSONTON                              Longitude:        82° 29.1' W


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


                         BENCH MARK STAMPING:  NO 3 1975

MONUMENTATION:           Survey Disk                               VM#:     6572
AGENCY:                                                            PID#:  AG7537
SETTING CLASSIFICATION:  Concrete Culvert


The bench mark is set flush in the south end of a concrete culvert, 0.3 mile
(0.5 km) north of the south end of Marina Drive, 128 feet (39 m) SE of the SE
corner of Building 60, and 16 feet (5 m) west of the centerline of Marina Drive.
 The bench mark is 1 foot (0.3 m) below road level.



                         BENCH MARK STAMPING:  F3-3X 1975

MONUMENTATION:           Survey Disk                               VM#:     6574
AGENCY:                                                            PID#:  AG7536
SETTING CLASSIFICATION:  Concrete Post


The bench mark is set in the top of a concrete post, 0.15 mile (0.24 km) north
of Bench Mark No 3 1975 along Marina Drive, 51.3 feet (15.6 m) NNW of a utility
pole, 14 feet (4 m) NW of a pine tree with a witness post attached, 13.8 feet
(4.2 m) east of the centerline of Marina Drive, and 1.2 feet (0.4 m) east of the
east edge of the road.  The bench mark is 0.5 foot (0.2 m) below ground level.



                         BENCH MARK STAMPING:  TH-110 1975

MONUMENTATION:           Survey Disk                               VM#:     6575
AGENCY:                                                            PID#:  AG7539
SETTING CLASSIFICATION:  Concrete Seawall


The bench mark is set flush in the west concrete seawall at the MacDill Air
Force Base Marina (Building 663), 118 feet (36 m) SSE of the NW corner of the
boat basin, and 77.5 feet (23.6 m) north of the NE corner of Building 663.

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

                                                   PUBLICATION DATE:  09/24/1985
Station ID: 8726573                                SUPERCEDED DATE:   04/21/2003
Name:       GADSDEN POINT, TAMPA BAY                          
            FLORIDA
NOAA Chart: 11412                                  Latitude:         27° 49.3' N
USGS Quad:  GIBSONTON                              Longitude:        82° 29.1' W


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


                         BENCH MARK STAMPING:  BUNKER 2 1956

MONUMENTATION:           Survey Disk                               VM#:     6576
AGENCY:                                                            PID#:  AG6114
SETTING CLASSIFICATION:  Concrete Monument


The bench mark is at the SW corner of the intersection of South Shore Road and
Marina Drive, 33.4 feet (10.2 m) west of the centerline of Marina Drive, 18 feet
(5 m) south of the centerline of South Shore Road, and 0.5 foot (0.2 m) north of
the wing wall of a culvert at a point of the west wing.  The bench mark is 0.2
foot (0.1 m) below ground level.

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

                                                   PUBLICATION DATE:  09/24/1985
Station ID: 8726573                                SUPERCEDED DATE:   04/21/2003
Name:       GADSDEN POINT, TAMPA BAY                          
            FLORIDA
NOAA Chart: 11412                                  Latitude:         27° 49.3' N
USGS Quad:  GIBSONTON                              Longitude:        82° 29.1' W


                            T I D A L   D A T U M S 


Tidal datums at GADSDEN POINT, TAMPA BAY based on:

     LENGTH OF SERIES:      1 MONTH
     TIME PERIOD:           DECEMBER 1975
     TIDAL EPOCH:           1960-1978
     CONTROL TIDE STATION:  8726520 ST. PETERSBURG


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

     HIGHEST OBSERVED WATER LEVEL (12/25/1975)         =   3.52
     MEAN HIGHER HIGH WATER                     MHHW   =   2.44
     MEAN HIGH WATER                            MHW    =   2.19
     MEAN TIDE LEVEL                            MTL    =   1.29
     MEAN LOW WATER                             MLW    =   0.39
     MEAN LOWER LOW WATER                       MLLW   =   0.00
     LOWEST  OBSERVED WATER LEVEL (12/19/1975)         =  -1.07

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In FEET above:

     Stamping or Designation                    MLLW        MHW

     NO 4 1975                                   6.95      4.76
     NO 2 1975                                   6.96      4.77
     NO 3 1975                                   8.09      5.90
     F3-3X 1975                                  6.77      4.58
     TH-110 1975                                 6.31      4.12
     BUNKER 2 1956                               7.49      5.30


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

                                                   PUBLICATION DATE:  09/24/1985
Station ID: 8726573                                SUPERCEDED DATE:   04/21/2003
Name:       GADSDEN POINT, TAMPA BAY                          
            FLORIDA
NOAA Chart: 11412                                  Latitude:         27° 49.3' N
USGS Quad:  GIBSONTON                              Longitude:        82° 29.1' 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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