Superseded Bench Mark Sheet for 8726711, WEST TAMPA, HILLSBOROUGH RIVER FL

Present Epoch

Printable version

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  4

                                                   PUBLICATION DATE:  07/22/1988
Station ID: 8726711                                SUPERCEDED DATE:   04/21/2003
Name:       WEST TAMPA, HILLSBOROUGH RIVER                    
            FLORIDA
NOAA Chart: 11413                                  Latitude:         27° 57.9' N
USGS Quad:  TAMPA                                  Longitude:        82° 28.5' W


To reach the tidal bench marks from the intersection of Oregon Avenue and Willow
Drive in Tampa, proceed south on Willow Drive to River Heights Marine and Dry
Dock (2305 North Willow Drive).  The bench marks are in the vicinity of the
marina.  The tide gage and staff were located on the northernmost dock of the
marina.


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


                 PRIMARY BENCH MARK STAMPING:  6711 A 1976

MONUMENTATION:           Survey Disk                               VM#:     7530
AGENCY:                                                            PID#:  AG7451
SETTING CLASSIFICATION:  Concrete Sea Wall


The bench mark is set flush in the concrete sea wall, 167 feet (51 m) north of
the centerline of the boat ramp, 35 feet (11 m) east of the centerline of the
parking lot driveway, and 25 feet (8 m) north of the west end of the center
pier.



                         BENCH MARK STAMPING:  6711 B 1976

MONUMENTATION:           Survey Disk                               VM#:     7531
AGENCY:                                                            PID#:  AG7452
SETTING CLASSIFICATION:  Concrete Sea Wall


The bench mark is set in the concrete sea wall, 156 feet (48 m) south of Bench
Mark 6711 A 1976, 37.6 feet (11.5 m) NE of the NE corner of the washroom, 37.4
feet (11.4 m) NE of Bench Mark 6711 F 1976, 11.0 feet (3.4 m) north of the
centerline of the boat ramp, and 3 feet (1 m) above the boat ramp.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  4

                                                   PUBLICATION DATE:  07/22/1988
Station ID: 8726711                                SUPERCEDED DATE:   04/21/2003
Name:       WEST TAMPA, HILLSBOROUGH RIVER                    
            FLORIDA
NOAA Chart: 11413                                  Latitude:         27° 57.9' N
USGS Quad:  TAMPA                                  Longitude:        82° 28.5' W


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


                         BENCH MARK STAMPING:  6711 C 1976

MONUMENTATION:           Survey Disk                               VM#:     7532
AGENCY:                                                            PID#:  AG7454
SETTING CLASSIFICATION:  Concrete Sea Wall


The bench mark is set in the top of the north sea wall for the dry dock ramp, 77
feet (23 m) east of the east side of the dry dock building, 51 feet (16 m) WSW
of Bench Mark 6711 E 1976, and 3 feet (1 m) above the ramp.



                         BENCH MARK STAMPING:  6711 E 1976

MONUMENTATION:           Survey Disk                               VM#:     7533
AGENCY:                                                            PID#:  AG7455
SETTING CLASSIFICATION:  Concrete Sign Base


The bench mark is set in the concrete sign base, 96.5 feet (29.4 m) SSW from
Bench Mark 6711 F 1976, 95 feet (29 m) SSE of the NE corner of the washroom, 18
feet (5 m) north of the north edge of the dry dock ramp, and 1 foot (0.3 m) NE
of a Super 5 Gas sign.



                         BENCH MARK STAMPING:  6711 F 1976

MONUMENTATION:           Survey Disk                               VM#:     7534
AGENCY:                                                            PID#:  AG7453
SETTING CLASSIFICATION:  Concrete Walkway


The bench mark is set in the concrete walkway, 17 feet (5 m) south of the
centerline of the boat ramp, 2.5 feet (0.8 m) north of the NE corner of the
washroom, and 2 feet (1 m) above the boat ramp.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  4

                                                   PUBLICATION DATE:  07/22/1988
Station ID: 8726711                                SUPERCEDED DATE:   04/21/2003
Name:       WEST TAMPA, HILLSBOROUGH RIVER                    
            FLORIDA
NOAA Chart: 11413                                  Latitude:         27° 57.9' N
USGS Quad:  TAMPA                                  Longitude:        82° 28.5' W


                            T I D A L   D A T U M S 


Tidal datums at WEST TAMPA, HILLSBOROUGH RIVER based on:

     LENGTH OF SERIES:      2 MONTHS
     TIME PERIOD:           DECEMBER 1976 - JANUARY 1977
     TIDAL EPOCH:           1960-1978
     CONTROL TIDE STATION:  8726639 BALLAST POINT


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

     HIGHEST OBSERVED WATER LEVEL (12/21/1976)         =   3.68
     MEAN HIGHER HIGH WATER                     MHHW   =   2.57
     MEAN HIGH WATER                            MHW    =   2.23
     MEAN TIDE LEVEL                            MTL    =   1.30
     MEAN LOW WATER                             MLW    =   0.37
     MEAN LOWER LOW WATER                       MLLW   =   0.00
     LOWEST  OBSERVED WATER LEVEL (12/01/1976)         =  -1.07

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In FEET above:

     Stamping or Designation                    MLLW        MHW

     6711 A 1976                                 5.12      2.89
     6711 B 1976                                 5.29      3.06
     6711 C 1976                                 6.25      4.02
     6711 E 1976                                 6.48      4.25
     6711 F 1976                                 5.53      3.30


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

                                                   PUBLICATION DATE:  07/22/1988
Station ID: 8726711                                SUPERCEDED DATE:   04/21/2003
Name:       WEST TAMPA, HILLSBOROUGH RIVER                    
            FLORIDA
NOAA Chart: 11413                                  Latitude:         27° 57.9' N
USGS Quad:  TAMPA                                  Longitude:        82° 28.5' 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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