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Bench Mark Sheet for 8720496, GREEN COVE SPRINGS, ST. JOHNS R. FL

Superseded Epoch

Large map location marker Station Location
Small red map location marker Published bench mark
Small blue map location marker Unpublished bench mark

Bench mark positions only appear on the map if their coordinates in the CO-OPS database are at the precision of degrees/minutes/seconds/and tenths of seconds. If the coordinates are less precise, the mark will not appear.

Printable version

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

                                                                                
Station ID: 8720496                         PUBLICATION DATE:  01/06/2004
Name:       GREEN COVE SPRINGS, ST. JOHNS R.                  
            FL
NOAA Chart: 11492                           Latitude:   29° 59.4' N (  29.99000)
USGS Quad:  GREEN COVE SPRINGS              Longitude:  81° 39.8' W ( -81.66330)


To reach the tidal bench marks from the intersection of U.S. Highway 17 and
Florida Highway 16, proceed south on Florida Highway 16 for 1.8 km (1.1 mi),
then north along the paved road into the fenced area of Reynolds Industrial
Park.  The bench marks are located along State Highway 16 and the road leading
from the highway to Pier 1 in the Industrial Park along the St. Johns River. 
The tide gage and staff were located on the south side of Pier 1.


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


                 PRIMARY BENCH MARK STAMPING:  1 1973

MONUMENTATION:           Tidal Station disk                    VM#:         5195
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AQ1552
SETTING CLASSIFICATION:  Concrete bulkhead cap                 OPUS PID#: AQ1552
LATITUDE:   29° 59.3' N (  29.98889)          LONGITUDE:  81° 39.8' W ( -81.66361)


The primary bench mark is a disk set flush in the top of the 0.61 m (2.0 ft)
wide concrete bulkhead cap at the SE intersection of the wharf and pier at Pier
1, 0.24 m (0.8 ft) south of the edge of the bulkhead, 0.24 m (0.8 ft) east of
the east side of the beginning of the pier, and 0.15 m (0.5 ft) above the road
and pier deck.



                         BENCH MARK STAMPING:  USC&GS G 123 1945

MONUMENTATION:           Bench Mark disk                       VM#:         5193
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AQ0007
SETTING CLASSIFICATION:  Concrete culvert                      OPUS PID:        
LATITUDE:   29° 59.4' N (  29.99000)          LONGITUDE:  81° 39.8' W ( -81.66330)


The bench mark is a disk set flush in the top center of a 0.3 m (1.0 ft) thick
concrete culvert, the north of two culverts between a divided highway in a grass
strip, 67 m (220 ft) west of the grass strip at the main gate road to the
entrance of the Reynolds property on the south side of Florida Route 16, and the
east road entrance to the piers on the north side of the highway, 8 m (25 ft)
south of the centerline of the north lane, 0.24 m (0.8 ft) west of the east end
of the culvert, and 1 m (3 ft) below the centerline of the north lane.

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

                                                                                
Station ID: 8720496                         PUBLICATION DATE:  01/06/2004
Name:       GREEN COVE SPRINGS, ST. JOHNS R.                  
            FL
NOAA Chart: 11492                           Latitude:   29° 59.4' N (  29.99000)
USGS Quad:  GREEN COVE SPRINGS              Longitude:  81° 39.8' W ( -81.66330)


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


                         BENCH MARK STAMPING:  2 1973

MONUMENTATION:           Tidal Station disk                    VM#:         5196
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AQ1549
SETTING CLASSIFICATION:  Concrete culvert                      OPUS PID:        
LATITUDE:   29° 59.4' N (  29.99000)          LONGITUDE:  81° 39.8' W ( -81.66330)


The bench mark is a disk set flush in the top of a 0.3 m (1.0 ft) thick concrete
culvert on State Route 16, north of one of two bench marks in the center grass
strip between the divided highway, 122 m (400 ft) east of the west road entrance
to Reynolds Piers, 8 m (25 ft) south of the centerline of the north lane, 6 m
(20 ft) east from where the highway divides, 0.15 m (0.5 ft) east of the west
end of the culvert, and 0.30 m (1.0 ft) below the highway.

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

                                                                                
Station ID: 8720496                         PUBLICATION DATE:  01/06/2004
Name:       GREEN COVE SPRINGS, ST. JOHNS R.                  
            FL
NOAA Chart: 11492                           Latitude:   29° 59.4' N (  29.99000)
USGS Quad:  GREEN COVE SPRINGS              Longitude:  81° 39.8' W ( -81.66330)


                                  D A T U M S 


Datums at GREEN COVE SPRINGS, ST. JOHNS R. based on:

     LENGTH OF SERIES:      1 YEAR
     TIME PERIOD:           April 1978 - March 1979
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8720220 MAYPORT


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

     HIGHEST OBSERVED WATER LEVEL (10/07/1974)         =  0.743
     MEAN HIGHER HIGH WATER                     MHHW   =  0.273
     MEAN HIGH WATER                            MHW    =  0.251
     MEAN TIDE LEVEL                            MTL    =  0.132
     MEAN SEA LEVEL                             MSL    =  0.131
     North American Vertical Datum              NAVD88 =  0.124
     MEAN LOW WATER                             MLW    =  0.012
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (04/01/1979)         = -0.623

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     1 1973                                      2.444    2.193
     USC&GS G 123 1945                       2.594    2.343
     2 1973                                      3.403    3.152


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

                                                                                
Station ID: 8720496                         PUBLICATION DATE:  01/06/2004
Name:       GREEN COVE SPRINGS, ST. JOHNS R.                  
            FL
NOAA Chart: 11492                           Latitude:   29° 59.4' N (  29.99000)
USGS Quad:  GREEN COVE SPRINGS              Longitude:  81° 39.8' W ( -81.66330)


                             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 NGS's Integrated Data Base (IDB PID)
provides geodetic datum based on traditionally leveled and bluebooked ties to
the National Spatial Reference System(NSRS) https://www.ngs.noaa.gov/datasheets/.
The NGS Online Positioning User Service (OPUS PID) provides geodetic datum based
on GPS position & tie it to the NSRS https://www.ngs.noaa.gov/OPUS/.

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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Products available at 8720496 GREEN COVE SPRINGS, ST. JOHNS R., FL

Revised: 10/15/2013
NOAA / National Ocean Service
Web site owner: Center for Operational Oceanographic Products and Services