Bench Mark Sheet for 8673381, HALFMOON, COLONELS ISLAND, TIMMONS RIVER GA

Superseded Epoch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Small blue map location marker Unpublished bench mark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  5

                                                                                
Station ID: 8673381                         PUBLICATION DATE:  03/09/2004
Name:       HALFMOON, COLONELS ISLAND, TIMMONS RIVER          
            GA
NOAA Chart: 11511                           Latitude:   31° 41.7' N (  31.69500)
USGS Quad:  SEABROOK                        Longitude:  81° 16.3' W ( -81.27170)


To reach the tidal bench marks from the intersection of Interstate Highway 95
and State Road 38, proceed east on State Road 38 for 13.2 km (8.2 mi) to the
road leading to Colonels Island Marina, then turn right and proceed south on the
road leading to Colonels Island Marina for 2.6 km (1.6 mi) to the marina.  The
bench marks are located on the marina grounds.  The tide gage and staff were
located on a pier on the NW corner of the marina.


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


                 PRIMARY BENCH MARK STAMPING:  3381 A 1977
                         DESIGNATION:          867 3381 A TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         4760
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Unspecified deep rod                  OPUS PID:        
LATITUDE:   31° 41.7' N (  31.69500)          LONGITUDE:  81° 16.3' W ( -81.27170)


The primary bench mark is a disk located near the NW corner of the southernmost
boat house, 16.70 m (54.8 ft) NE of a group of four oak trees east of Timmons
River, and 10.15 m (33.3 ft) north of the NE corner of a small wooden building. 
The bench mark is crimped to the top of an unspecified rod driven 19.5 m (64 ft)
to refusal and encased in a PVC pipe and concrete kickblock.

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

                                                                                
Station ID: 8673381                         PUBLICATION DATE:  03/09/2004
Name:       HALFMOON, COLONELS ISLAND, TIMMONS RIVER          
            GA
NOAA Chart: 11511                           Latitude:   31° 41.7' N (  31.69500)
USGS Quad:  SEABROOK                        Longitude:  81° 16.3' W ( -81.27170)


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


                         BENCH MARK STAMPING:  3381 B 1977
                         DESIGNATION:          867 3381 B TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         4761
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Unspecified deep rod                  OPUS PID:        
LATITUDE:   31° 41.7' N (  31.69500)          LONGITUDE:  81° 16.3' W ( -81.27170)


The bench mark is a disk located near the SE corner of the northernmost boat
house, 86 m (283 ft) east of bench mark 3381 A 1977, and 8.99 m (29.5 ft) west
of the centerline of the road leading to the marina.  The bench mark is crimped
to the top of an unspecified rod driven 1.8 m (6 ft) to refusal and encased in a
PVC pipe and concrete kickblock.



                         BENCH MARK STAMPING:  3381 C 1977
                         DESIGNATION:          867 3381 C TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         4762
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Unspecified deep rod                  OPUS PID:        
LATITUDE:   31° 41.7' N (  31.69500)          LONGITUDE:  81° 16.3' W ( -81.27170)


The bench mark is a disk located NE of a cinder block cottage, 52.82 m (173.3
ft) south of bench mark 3381 B 1977, 17.77 m (58.3 ft) NE of the NE corner of
the cinder block cottage, and 9.69 m (31.8 ft) west of the centerline of the
road leading to the marina.  The bench mark is set 6 cm (0.2 ft) above ground
level, crimped to the top of an unspecified rod driven 4.9 m (16 ft) to refusal,
and encased in a PVC pipe and concrete kickblock.

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

                                                                                
Station ID: 8673381                         PUBLICATION DATE:  03/09/2004
Name:       HALFMOON, COLONELS ISLAND, TIMMONS RIVER          
            GA
NOAA Chart: 11511                           Latitude:   31° 41.7' N (  31.69500)
USGS Quad:  SEABROOK                        Longitude:  81° 16.3' W ( -81.27170)


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


                         BENCH MARK STAMPING:  3381 D 1977
                         DESIGNATION:          867 3381 D TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         4763
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Unspecified deep rod                  OPUS PID:        
LATITUDE:   31° 41.7' N (  31.69500)          LONGITUDE:  81° 16.3' W ( -81.27170)


The bench mark is a disk located south of a cinder block cottage, 30.69 m (100.7
ft) SSW of bench mark 3381 C 1977, 16.92 m (55.5 ft) west of the centerline of
the road leading to the marina, and 5.91 m (19.4 ft) ESE of the SE corner of the
cinder block cottage.  The bench mark is set 6 cm (0.2 ft) above ground level,
crimped to the top of an unspecified rod driven 4.9 m (16 ft) to refusal, and
encased in a PVC pipe and a concrete kickblock.



                         BENCH MARK STAMPING:  3381 E 1977
                         DESIGNATION:          867 3381 E TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         4764
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Unspecified deep rod                  OPUS PID:        
LATITUDE:   31° 41.7' N (  31.69500)          LONGITUDE:  81° 16.3' W ( -81.27170)


The bench mark is a disk located ESE of the marina store, 48 m (158 ft) west of
bench mark 3381 D 1977, and 16.34 m (53.6 ft) ESE of the SE corner of the marina
store.  The bench mark is crimped to the top of an unspecified rod driven 2.4 m
(8 ft) to refusal, and encased in a PVC pipe and a concrete kickblock.

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

                                                                                
Station ID: 8673381                         PUBLICATION DATE:  03/09/2004
Name:       HALFMOON, COLONELS ISLAND, TIMMONS RIVER          
            GA
NOAA Chart: 11511                           Latitude:   31° 41.7' N (  31.69500)
USGS Quad:  SEABROOK                        Longitude:  81° 16.3' W ( -81.27170)


                            T I D A L   D A T U M S 


Tidal datums at HALFMOON, COLONELS ISLAND, TIMMONS RIVER based on:

     LENGTH OF SERIES:      1 MONTH
     TIME PERIOD:           May 1977 - May 1977
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8720030 FERNANDINA BEACH, AMELIA RIVER


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

     MEAN HIGHER HIGH WATER                     MHHW   =  2.422
     MEAN HIGH WATER                            MHW    =  2.311
     MEAN SEA LEVEL                             MSL    =  1.338
     MEAN TIDE LEVEL                            MTL    =  1.190
     MEAN LOW WATER                             MLW    =  0.069
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     3381 A 1977                                 4.815    2.504
     3381 B 1977                                 5.615    3.304
     3381 C 1977                                 5.856    3.545
     3381 D 1977                                 5.806    3.495
     3381 E 1977                                 5.556    3.245


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

                                                                                
Station ID: 8673381                         PUBLICATION DATE:  03/09/2004
Name:       HALFMOON, COLONELS ISLAND, TIMMONS RIVER          
            GA
NOAA Chart: 11511                           Latitude:   31° 41.7' N (  31.69500)
USGS Quad:  SEABROOK                        Longitude:  81° 16.3' W ( -81.27170)


                             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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