Superseded Bench Mark Sheet for 8720832, Welaka FL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:  04/04/1991
Station ID: 8720832                                SUPERCEDED DATE:   04/21/2003
Name:       WELAKA, ST. JOHNS RIVER                           
            FLORIDA
NOAA Chart: 11495                                  Latitude:         29° 28.6' N
USGS Quad:  WELAKA                                 Longitude:        81° 40.5' W


To reach the tidal bench marks from the intersection of State Road 308B (Oak
Street) and State Road 309 in Welaka, proceed west on State Road 308B for  0.15
mile (0.24 km) to Front Street, then south on Front Street for 0.3 mile (0.5 km)
to the dirt road leading west to the Greene residence, the house just to the
north of Trail Boss Campgrounds.  The bench marks are along Front and Elm
Streets.  The tide gage and staff were on the west end of the northernmost
finger dock behind the Greene residence.


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


                 PRIMARY BENCH MARK STAMPING:   

MONUMENTATION:                                                     VM#:    16183
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  






                         BENCH MARK STAMPING:  N 19 1933 22.903

MONUMENTATION:           Survey Disk                               VM#:     5256
AGENCY:                                                            PID#:  AQ0678
SETTING CLASSIFICATION:  Concrete Monument


The bench mark is set in the top of a concrete monument at the intersection of
Front and Elm Streets, across from Welaka Civic Hall, 30 feet (9 m) north of the
centerline of Elm Street, 29 feet (9 m) east of the centerline of Front Street,
2 feet (1 m) east of a flagpole at the SW corner of a concrete block building,
and 0.1 foot (0.03 m) above ground level.

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

                                                   PUBLICATION DATE:  04/04/1991
Station ID: 8720832                                SUPERCEDED DATE:   04/21/2003
Name:       WELAKA, ST. JOHNS RIVER                           
            FLORIDA
NOAA Chart: 11495                                  Latitude:         29° 28.6' N
USGS Quad:  WELAKA                                 Longitude:        81° 40.5' W


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


                         BENCH MARK STAMPING:  NO 1 1934

MONUMENTATION:           Survey Disk                               VM#:     5257
AGENCY:                                                            PID#:  AQ2571
SETTING CLASSIFICATION:  Concrete Monument


The bench mark is set in a concrete monument at the intersection of Front and
Palmetto Streets, 41.2 feet (12.6 m) east of the centerline of Front Street,
18.6 feet (5.7 m) north of the centerline of Palmetto Street, 0.5 foot (0.2 m)
NW of power pole #3-3724-1203-0-6, and 0.3 foot (0.1 m) above ground level.



                         BENCH MARK STAMPING:  WELAKA 1935

MONUMENTATION:           Survey Disk                               VM#:     5258
AGENCY:                                                            PID#:  AQ1775
SETTING CLASSIFICATION:  Concrete Monument


The bench mark is set in a square concrete monument in an open area near the
river, 265 feet (81 m) south of the post office, 150 feet (46 m) east of the
river, 132 feet (40 m) west of the centerline of a paved street, 49 feet   (15
m) SSE of the SW corner of an old garage, 14 feet (4 m) north of a yard fence, 1
foot (0.3 m) east of a metal witness post, and 0.2 foot (0.1 m) above ground
level.



                         BENCH MARK STAMPING:  WELAKA 1935 NO 4 1968

MONUMENTATION:           Survey Disk                               VM#:     5259
AGENCY:                                                            PID#:  AQ1774
SETTING CLASSIFICATION:  Concrete Monument


The bench mark is set in a concrete monument in the SE corner of an open area,
150 feet (46 m) east of the river, 30 feet (9 m) west of the centerline of a
paved street, 2.2 feet (0.7 m) north of the fence corner with a 3 x 3-inch
square concrete property corner stake, and at ground level.

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

                                                   PUBLICATION DATE:  04/04/1991
Station ID: 8720832                                SUPERCEDED DATE:   04/21/2003
Name:       WELAKA, ST. JOHNS RIVER                           
            FLORIDA
NOAA Chart: 11495                                  Latitude:         29° 28.6' N
USGS Quad:  WELAKA                                 Longitude:        81° 40.5' W


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


                         BENCH MARK STAMPING:  0832 A 1978

MONUMENTATION:           Survey Disk                               VM#:     5260
AGENCY:                                                            PID#:  AQ1778
SETTING CLASSIFICATION:  Concrete Monument


The primary bench mark is set flush in the top of a 4-foot (1 m) deep bell-
shaped concrete monument, 76.3 feet (23.3 m) NW of the office at Trail Boss
Campgrounds, 54.8 feet (16.7 m) west of the SW corner of the Greene residence,
47.9 feet (14.6 m) SE of the beginning of the ladder which leads down to the
dock, 0.5 foot (0.2 m) west of the property marker at the SW corner of Greene's
property, and at ground level.



                         BENCH MARK STAMPING:  0832 B 1978

MONUMENTATION:           Survey Disk                               VM#:     5261
AGENCY:                                                            PID#:  AQ1777
SETTING CLASSIFICATION:  Concrete Monument


The bench mark is set flush in the top of a 4-foot (1 m) deep bell-shaped
concrete monument, 0.15 mile (0.24 km) south of the intersection of Front and
Oak Streets, 72.6 feet (22.1 m) SW of a culvert on the east side of Front
Street, 26.4 feet (8.0 m) west of the centerline of Front Street, 18.2 feet (5.5
m) south of the centerline of the dirt road leading west into Wolfe's Fishing
Camp, 1 foot (0.3 m) SW of power pole #3-3723-1676-0-1 with witness sign, and at
ground level.

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

                                                   PUBLICATION DATE:  04/04/1991
Station ID: 8720832                                SUPERCEDED DATE:   04/21/2003
Name:       WELAKA, ST. JOHNS RIVER                           
            FLORIDA
NOAA Chart: 11495                                  Latitude:         29° 28.6' N
USGS Quad:  WELAKA                                 Longitude:        81° 40.5' W


                            T I D A L   D A T U M S 


Tidal datums at WELAKA, ST. JOHNS RIVER based on:

     LENGTH OF SERIES:      5 MONTHS
     TIME PERIOD:           SEPTEMBER 1978-MARCH 1979
     TIDAL EPOCH:           1960-1978
     CONTROL TIDE STATION:  8720496 GREEN COVE SPRINGS


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

     HIGHEST OBSERVED WATER LEVEL (11/04/1978)         =   1.53
     MEAN HIGHER HIGH WATER                     MHHW   =   0.42
     MEAN HIGH WATER                            MHW    =   0.39
     MEAN TIDE LEVEL                            MTL    =   0.22
     MEAN LOW WATER                             MLW    =   0.04
     MEAN LOWER LOW WATER                       MLLW   =   0.00
     LOWEST  OBSERVED WATER LEVEL (04/10/1979)         =  -0.97

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In FEET above:

     Stamping or Designation                    MLLW        MHW

     0                                           0.00      0.00
     N 19 1933 22.903                           22.22     21.83
     NO 1 1934                                  22.52     22.13
     WELAKA 1935                                22.15     21.76
     WELAKA 1935 NO 4 1968                      23.14     22.75
     0832 A 1978                                17.16     16.77
     0832 B 1978                                17.27     16.88


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

                                                   PUBLICATION DATE:  04/04/1991
Station ID: 8720832                                SUPERCEDED DATE:   04/21/2003
Name:       WELAKA, ST. JOHNS RIVER                           
            FLORIDA
NOAA Chart: 11495                                  Latitude:         29° 28.6' N
USGS Quad:  WELAKA                                 Longitude:        81° 40.5' 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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