Superseded Bench Mark Sheet for 8729376, SANTA ROSA HOGTOWN BAYOU FL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:  06/11/1984
Station ID: 8729376                                SUPERCEDED DATE:   04/21/2003
Name:       SANTA ROSA, HOGTOWN BAYOU, CHOCTAWHATCHEE BAY     
            FLORIDA
NOAA Chart: 11388                                  Latitude:         30° 23.9' N
USGS Quad:  FREEPORT                               Longitude:        86° 13.7' W


To reach the tidal bench marks from the intersection of U.S. Highway 98 and
State Highway 393 in Santa Rosa Beach, proceed north on State Highway 393 1.5
miles (2.4 km) to the Lions Park on the south shore of Hogtown Bayou.  The bench
marks are located in the vicinity of Lions Park and along State Highway 393. 
The tide gage and staff were 190 feet (58 m) west of the highway and 30 feet (9
m) NE of a boat launching ramp.


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


                 PRIMARY BENCH MARK STAMPING:  9376 A 1977

MONUMENTATION:           Survey Disk                               VM#:    10101
AGENCY:                                                            PID#:  BG3580
SETTING CLASSIFICATION:  Concrete Chimney Foundation


The bench mark is behind the Lions Park sign, 285 feet (87 m) west of the
centerline of State Highway 393, 52.5 feet (16.0 m) SE of the SE corner of the
westernmost covered picnic table, 5.0 feet (1.5 m) north of a light pole, set
flush into a concrete chimney foundation, and 3.5 feet (1.1 m) above ground.



                         BENCH MARK STAMPING:  9376 B 1977

MONUMENTATION:           Survey Disk                               VM#:    10102
AGENCY:                                                            PID#:  BG3581
SETTING CLASSIFICATION:  Retaining Wall


The bench mark is 240 feet (73 m) SW of Bench Mark 1 1939, west of the western
bridge guardrail, in the SW corner of the bridge over Hogtown Bayou, 14 feet (4
m) west of the centerline of the bridge, set flush in the concrete, and 1.5 feet
(0.5 m) above the road.

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

                                                   PUBLICATION DATE:  06/11/1984
Station ID: 8729376                                SUPERCEDED DATE:   04/21/2003
Name:       SANTA ROSA, HOGTOWN BAYOU, CHOCTAWHATCHEE BAY     
            FLORIDA
NOAA Chart: 11388                                  Latitude:         30° 23.9' N
USGS Quad:  FREEPORT                               Longitude:        86° 13.7' W


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


                         BENCH MARK STAMPING:  1 1939

MONUMENTATION:           Survey Disk                               VM#:    10103
AGENCY:                                                            PID#:  BG3582
SETTING CLASSIFICATION:  Concrete Post


The bench mark is north of the bridge over Hogtown Bayou, 47 feet (14 m) north
of the shoreline, 41 feet (12 m) past of the centerline of State Highway 393, 29
feet (9 m) west of the gate of the fence enclosing the front yard at the
residence of Mrs. Elizabeth Collins, 1.0 foot (0.3 m) south of the fence, set
into the top of a 0.8 foot (0.2 m) square concrete post and projecting 0.2 foot
(0.1 m) above ground.



                         BENCH MARK STAMPING:  3 1939

MONUMENTATION:           Survey Disk                               VM#:    10104
AGENCY:                                                            PID#:  BG3583
SETTING CLASSIFICATION:  Concrete Post


The bench mark is north of the bridge over Hogtown Bayou, 166 feet (51 m) east
of the centerline of State Highway 393, 85 feet (26 m) east of the SE corner of
the Collins residence, 58 feet (18 m) north of the shoreline, 10.0 feet (3.0 m)
east of the yard fence, set into the top of a 0.8 foot (0.2 m) square concrete
post and projecting 0.2 foot (0.1 m) above ground.

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

                                                   PUBLICATION DATE:  06/11/1984
Station ID: 8729376                                SUPERCEDED DATE:   04/21/2003
Name:       SANTA ROSA, HOGTOWN BAYOU, CHOCTAWHATCHEE BAY     
            FLORIDA
NOAA Chart: 11388                                  Latitude:         30° 23.9' N
USGS Quad:  FREEPORT                               Longitude:        86° 13.7' W


                            T I D A L   D A T U M S 


Tidal datums at SANTA ROSA, HOGTOWN BAYOU, CHOCTAWHATCHEE BAY based on:

     LENGTH OF SERIES:      3 MONTHS
     TIME PERIOD:           APRIL-JUNE 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 (09/04/1977)         =   1.78
     MEAN HIGHER HIGH WATER                     MHHW   =   0.44
     MEAN HIGH WATER                            MHW    =   0.44
     MEAN TIDE LEVEL                            MTL    =   0.22
     MEAN LOW WATER                             MLW    =   0.01
     MEAN LOWER LOW WATER                       MLLW   =   0.00
     LOWEST  OBSERVED WATER LEVEL (04/10/1977)         =  -0.58

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In FEET above:

     Stamping or Designation                    MLLW        MHW

     9376 A 1977                                 5.85      5.41
     9376 B 1977                                 6.28      5.84
     1 1939                                      2.46      2.02
     3 1939                                      2.78      2.34


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

                                                   PUBLICATION DATE:  06/11/1984
Station ID: 8729376                                SUPERCEDED DATE:   04/21/2003
Name:       SANTA ROSA, HOGTOWN BAYOU, CHOCTAWHATCHEE BAY     
            FLORIDA
NOAA Chart: 11388                                  Latitude:         30° 23.9' N
USGS Quad:  FREEPORT                               Longitude:        86° 13.7' 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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