Superseded Bench Mark Sheet for 8675761, Daymark #185, Rockdedundy River Entrance GA

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:  01/22/1985
Station ID: 8675761                                SUPERCEDED DATE:   04/21/2003
Name:       DAY MARK #185, ROCKDEDUNDY RIVER ENTRANCE         
            GEORGIA
NOAA Chart: 11510                                  Latitude:         31° 22.4' N
USGS Quad:  ALTAMAHA SOUND                         Longitude:        81° 20.1' W


To reach the tidal bench marks proceed by boat 0.5 NM (0.9 km) north of the
intersection of South and Little Mud Rivers and a point of land opposite the
mouth of Rockdedundy River.  The bench marks are located on the east bank of the
intercoastal waterway adjacent to Day Mark 185.  The tide gage and staff were
located on the Day Mark 185 structure.


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


                 PRIMARY BENCH MARK STAMPING:  5761 A 1980

MONUMENTATION:           Survey Disk                               VM#:     4896
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Unspecified Rod


The bench mark is located on the east bank of the intercoastal waterway adjacent
to Day Mark 185, 160.0 feet (48.8 m) west of a small hammock, bearing ESE of Day
Mark 185, south of Day Mark 184 and NE of Day Mark 188.  The bench mark is 0.9
foot (0.3 m) above ground level set atop a rod driven to refusal at 60.0 feet
(18.3 m), and encased in a 4-inch PVC pipe and concrete kickblock.



                         BENCH MARK STAMPING:  2

MONUMENTATION:           Monel Rivet                               VM#:     4894
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Monument


The bench mark is located on the east bank of the intercoastal waterway adjacent
to Day Mark 185, 115.0 feet (35.0 m) west of the shoreline, 60.0 feet (18.3 m)
west of U.S. Army War Department Corps of Engineers Bench Mark NO 1 1949 and
bearing east of Day Mark 185 and NE of Day Mark 188.  The bench mark is set into
a 0.7 foot (0.2 m) x 0.7 foot (0.2 m) concrete monument which extends 1.3 feet
(0.4 m) above ground.

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

                                                   PUBLICATION DATE:  01/22/1985
Station ID: 8675761                                SUPERCEDED DATE:   04/21/2003
Name:       DAY MARK #185, ROCKDEDUNDY RIVER ENTRANCE         
            GEORGIA
NOAA Chart: 11510                                  Latitude:         31° 22.4' N
USGS Quad:  ALTAMAHA SOUND                         Longitude:        81° 20.1' W


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


                         BENCH MARK STAMPING:  NO 1 1949

MONUMENTATION:           Survey Disk                               VM#:     4895
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Monument


The bench mark is located on the east bank of the intercoastal waterway adjacent
to Day Mark 185, 86.0 feet (26.2 m) NE of Bench Mark 5761 A 1980, 75.0 feet
(22.9 m) west of the shoreline, and bearing NE of Day Mark 188.  The bench mark
is set into a 0.7 foot (0.2 m) x 0.7 foot (0.2 m) concrete monument which
extends 0.5 foot above ground.



                         BENCH MARK STAMPING:  5761 B 1980

MONUMENTATION:           Survey Disk                               VM#:     4897
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Unspecified Rod


The bench mark is located on the east bank of the intercoastal waterway in a
small hammock clearing adjacent to Day Mark 185, 175 feet (53.7 m) west of the
shoreline, 30.0 feet (9.1 m) SE from Bench Mark NO STAMPING 1, bearing ENE from
Day Mark 185, and NW from the Rockdedundy Range Forward Marker.  The bench mark
is set atop a deep driven rod driven 60 feet (18.3 m) to refusal encased in a
4-inch PVC pipe and concrete kickblock.

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

                                                   PUBLICATION DATE:  01/22/1985
Station ID: 8675761                                SUPERCEDED DATE:   04/21/2003
Name:       DAY MARK #185, ROCKDEDUNDY RIVER ENTRANCE         
            GEORGIA
NOAA Chart: 11510                                  Latitude:         31° 22.4' N
USGS Quad:  ALTAMAHA SOUND                         Longitude:        81° 20.1' W


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


                         BENCH MARK STAMPING:  NO STAMPING 1

MONUMENTATION:           Monel Rivet                               VM#:     4898
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Monument


The bench mark is located on the east bank of the intercoastal waterway adjacent
to Day Mark 185, 155.0 feet (47.2 m) west of the shoreline, 57.0 feet (17.4 m)
ENE from Bench Mark 2, bearing east of Day Mark 185 and NE of Day Mark 188.  The
bench mark is set into a 0.7 foot (0.2 m) x 0.7 foot (0.2 m) concrete monument
which extends 1.3 feet (0.4 m) above ground.

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

                                                   PUBLICATION DATE:  01/22/1985
Station ID: 8675761                                SUPERCEDED DATE:   04/21/2003
Name:       DAY MARK #185, ROCKDEDUNDY RIVER ENTRANCE         
            GEORGIA
NOAA Chart: 11510                                  Latitude:         31° 22.4' N
USGS Quad:  ALTAMAHA SOUND                         Longitude:        81° 20.1' W


                            T I D A L   D A T U M S 


Tidal datums at DAY MARK #185, ROCKDEDUNDY RIVER ENTRANCE based on:

     LENGTH OF SERIES:      77 HW & 77 LW
     TIME PERIOD:           APRIL 10 - MAY 19, 1980
     TIDAL EPOCH:           1960-1978
     CONTROL TIDE STATION:  8670870 FT. PULASKI


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

     HIGHEST OBSERVED WATER LEVEL (05/16/1980)         =   9.52
     MEAN HIGHER HIGH WATER                     MHHW   =   7.52
     MEAN HIGH WATER                            MHW    =   7.13
     MEAN TIDE LEVEL                            MTL    =   3.70
     MEAN LOW WATER                             MLW    =   0.27
     MEAN LOWER LOW WATER                       MLLW   =   0.00
     LOWEST  OBSERVED WATER LEVEL (04/15/1980)         =  -2.22



Bench Mark Elevation Information                In FEET above:

     Stamping or Designation                    MLLW        MHW

     5761 A 1980                                 7.63      0.50
     2                                           8.84      1.71
     NO 1 1949                                   7.71      0.58
     5761 B 1980                                 9.03      1.90
     NO STAMPING 1                               9.42      2.29


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

                                                   PUBLICATION DATE:  01/22/1985
Station ID: 8675761                                SUPERCEDED DATE:   04/21/2003
Name:       DAY MARK #185, ROCKDEDUNDY RIVER ENTRANCE         
            GEORGIA
NOAA Chart: 11510                                  Latitude:         31° 22.4' N
USGS Quad:  ALTAMAHA SOUND                         Longitude:        81° 20.1' 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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Products available at 8675761 Daymark #185, Rockdedundy River Entrance, GA