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Bench Mark Sheet for 8667783, OTTER ISLAND, ST. HELENA SOUND SC

Superseded Epoch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Small blue map location marker Unpublished bench mark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: 8667783                         PUBLICATION DATE:  05/16/2003
Name:       OTTER ISLAND, ST. HELENA SOUND                    
            SC
NOAA Chart: 11517                           Latitude:   32° 28.6' N (  32.47670)
USGS Quad:  ST HELENA SOUND                 Longitude:  80° 25.2' W ( -80.42000)


To reach the tidal bench marks from U.S. Highway 17 in Jacksonboro, proceed
south on U.S. Highway 17 for 13 km (8 mi), crossing Ashepoo River, to a rest
area and the intersection of State Road S-15-26, turn left on State Road S-15-26
and go 25.1 km (15.6 mi) to the end of the pavement, turn right onto the dirt
road and continue 0.3 km (0.2 mi) to the boat ramps at Bennetts Point, continue
by boat for about 12.4 km (6.7 nautical mi) down the Ashepoo River to Otter
Island.  The bench marks are behind the berm line and west of the dense brush on
the beach of Otter Island.  The tide gage and staff were on a platform
constructed offshore of the west side of the island at the mouth of Ashepoo
River at St. Helena Sound.


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


                 PRIMARY BENCH MARK STAMPING:  7783 A 1978
                         DESIGNATION:          866 7783 A TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         4395
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Galvanized steel rod                  OPUS PID:        
LATITUDE:   32° 28.6' N (  32.47670)          LONGITUDE:  80° 25.2' W ( -80.42000)


The primary bench mark is a disk crimped to a galvanized steel rod, located
41.85 m (137.3 ft) NNW of Bench Mark 7783 B 1978, and 1.25 m (4.1 ft) WSW of a
metal witness post. The bench mark is 0.09 m (0.3 ft) above the ground, crimped
to a galvanized steel rod driven 12 m (38 ft) to refusal, and encased in a
4-inch PVC pipe and concrete kickblock.

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

                                                                                
Station ID: 8667783                         PUBLICATION DATE:  05/16/2003
Name:       OTTER ISLAND, ST. HELENA SOUND                    
            SC
NOAA Chart: 11517                           Latitude:   32° 28.6' N (  32.47670)
USGS Quad:  ST HELENA SOUND                 Longitude:  80° 25.2' W ( -80.42000)


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


                         BENCH MARK STAMPING:  7783 B 1978
                         DESIGNATION:          866 7783 B TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         4396
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID:        
LATITUDE:   32° 28.6' N (  32.47670)          LONGITUDE:  80° 25.2' W ( -80.42000)


The bench mark is a disk set in the top of a concrete monument, 46 m (151 ft)
north of Bench Mark 7783 C 1978, 1.13 m (3.7 ft) west of a metal witness post,
and 0.09 m (0.3 ft) above the ground.



                         BENCH MARK STAMPING:  7783 C 1978
                         DESIGNATION:          866 7783 C TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         4397
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Galvanized steel rod                  OPUS PID:        
LATITUDE:   32° 28.6' N (  32.47670)          LONGITUDE:  80° 25.2' W ( -80.42000)


The bench mark is a disk crimped to a galvanized steel rod, located 50.38 m
(165.3 ft) feet NNE of Bench Mark 7783 D 1978, and 1.22 m (4.0 ft) west of a
metal witness post.  The bench mark is 0.09 m (0.3 ft) above the ground, crimped
to a galvanized steel rod driven 7 m (22 ft) to refusal, and 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

                                                                                
Station ID: 8667783                         PUBLICATION DATE:  05/16/2003
Name:       OTTER ISLAND, ST. HELENA SOUND                    
            SC
NOAA Chart: 11517                           Latitude:   32° 28.6' N (  32.47670)
USGS Quad:  ST HELENA SOUND                 Longitude:  80° 25.2' W ( -80.42000)


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


                         BENCH MARK STAMPING:  7783 D 1978
                         DESIGNATION:          866 7783 D TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         4398
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Concrete momument                     OPUS PID:        
LATITUDE:   32° 28.6' N (  32.47670)          LONGITUDE:  80° 25.2' W ( -80.42000)


The bench mark is a disk set in the top of a concrete monument, 44.17 m (144.9
ft) north of Bench Mark 7783 E 1978, 0.85 m (2.8 ft) west of a metal witness
post, and 0.03 m (0.1 ft) above the ground.



                         BENCH MARK STAMPING:  7783 E 1978
                         DESIGNATION:          866 7783 E TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         4399
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Galvinized steel rod                  OPUS PID:        
LATITUDE:   32° 28.6' N (  32.47670)          LONGITUDE:  80° 25.2' W ( -80.42000)


The bench mark is a disk crimped to a galvanized steel rod, located 13.41 m
(44.0 ft) west of a 0.15 m (0.5 ft) diameter twin cedar tree, and 1.04 m (3.4
ft) west of a metal witness post. The bench mark is 0.09 m (0.3 ft) above the
ground, crimped to a galvanized steel rod driven 6.71 m (22.0 ft) to refusal,
and encased in a 4-inch PVC pipe and concrete kickblock.

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

                                                                                
Station ID: 8667783                         PUBLICATION DATE:  05/16/2003
Name:       OTTER ISLAND, ST. HELENA SOUND                    
            SC
NOAA Chart: 11517                           Latitude:   32° 28.6' N (  32.47670)
USGS Quad:  ST HELENA SOUND                 Longitude:  80° 25.2' W ( -80.42000)


                            T I D A L   D A T U M S 


Tidal datums at OTTER ISLAND, ST. HELENA SOUND based on:

     LENGTH OF SERIES:      8 MONTHS
     TIME PERIOD:           April 1978 - November 1978
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8667999 BEAUFORT


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

     MEAN HIGHER HIGH WATER                     MHHW   =  2.004
     MEAN HIGH WATER                            MHW    =  1.895
     MEAN SEA LEVEL                             MSL    =  1.023
     MEAN TIDE LEVEL                            MTL    =  0.979
     MEAN LOW WATER                             MLW    =  0.064
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     7783 A 1978                                 2.536    0.641
     7783 B 1978                                 2.542    0.647
     7783 C 1978                                 2.638    0.743
     7783 D 1978                                 2.513    0.618
     7783 E 1978                                 2.621    0.726


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

                                                                                
Station ID: 8667783                         PUBLICATION DATE:  05/16/2003
Name:       OTTER ISLAND, ST. HELENA SOUND                    
            SC
NOAA Chart: 11517                           Latitude:   32° 28.6' N (  32.47670)
USGS Quad:  ST HELENA SOUND                 Longitude:  80° 25.2' W ( -80.42000)


                             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 8667783 OTTER ISLAND, ST. HELENA SOUND, SC

Revised: 08/08/2018
NOAA / National Ocean Service
Web site owner: Center for Operational Oceanographic Products and Services