Bench Mark Sheet for 8665192, WANDO RIVER ENTRANCE, HOBCAW POINT 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Superseded Epoch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Small blue map location marker Unpublished bench mark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  4

                                                                                
Station ID: 8665192                         PUBLICATION DATE:  10/30/2003
Name:       WANDO RIVER ENTRANCE                              
            SC
NOAA Chart: 11524                           Latitude:   32° 49.3' N (  32.82170)
USGS Quad:  CHARLESTON                      Longitude:  79° 54.0' W ( -79.90000)


To reach the tidal bench marks from Cooper River Bridge on U.S. Highway 17,
proceed NE on U.S. Highway 17 for 1.0 km (0.6 mi) to State Road S-10-56 (Mathis
Ferry Road), then NW on State Road S-10-56 for 1.4 km (0.9 mi) to Muirhead Road,
then turn left and proceed north on Muirhead Road for 0.8 km (0.5 mi) to a fork
in the road, then turn left and proceed NE on Hobcaw Drive for 1.8 km (1.1 mi)
to the third house (E.K. Pritchard residence) west of Hobcaw Yacht Club.  The
bench marks are along Hobcaw Drive, on the yacht club property, and on the
Pritchard property.  The tide gage and staff were on the pier behind the
Pritchard residence.


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


                 PRIMARY BENCH MARK STAMPING:  5192 D 1976
                         DESIGNATION:          866 5192 D TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         4147
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  CJ0296
SETTING CLASSIFICATION:  Copper-clad steel rod                 OPUS PID:        
LATITUDE:   32° 49.3' N (  32.82170)          LONGITUDE:  79° 53.9' W ( -79.89830)


The primary bench mark is a disk set near the entrance to Hobcaw Yacht Club,
5.64 m (18.5 ft) north of the centerline of Hobcaw Drive, 3.20 m (10.5 ft) west
of the eastern- most brick gate post of the yacht club, and 0.85 m (2.8 ft) NW
of utility pole #C-42044.  The bench mark is set at ground level, crimped to the
top of a copper-clad steel rod driven 14.6 m (48 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  4

                                                                                
Station ID: 8665192                         PUBLICATION DATE:  10/30/2003
Name:       WANDO RIVER ENTRANCE                              
            SC
NOAA Chart: 11524                           Latitude:   32° 49.3' N (  32.82170)
USGS Quad:  CHARLESTON                      Longitude:  79° 54.0' W ( -79.90000)


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


                         BENCH MARK STAMPING:  HOBCAW 2 1976
                         DESIGNATION:          866 5192 TIDAL HOBCAW 2

MONUMENTATION:           Tidal Station disk                    VM#:         4150
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  CJ1478
SETTING CLASSIFICATION:  Asphalt driveway                      OPUS PID:        
LATITUDE:   32° 49.3' N (  32.82170)          LONGITUDE:  79° 54.0' W ( -79.90000)


The bench mark is a disk set in the asphalt driveway leading to Hobcaw Yacht
Club, 5.30 m (17.4 ft) east of the SE corner of the swimming pool pump house,
2.44 m (8.0 ft) west of the centerline of the driveway, 1.95 m (6.4 ft) SE of
the west side of a galvanized fence gate, and 1.10 m (3.6 ft) south of the NW
end of the driveway.



                         BENCH MARK STAMPING:  HOBCAW 3 1976
                         DESIGNATION:          866 5192 TIDAL HOBCAW 3

MONUMENTATION:           Tidal Station disk                    VM#:         4151
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  CJ0297
SETTING CLASSIFICATION:  Asphalt driveway                      OPUS PID:        
LATITUDE:   32° 49.3' N (  32.82170)          LONGITUDE:  79° 53.9' W ( -79.89830)


The bench mark is a disk set flush in the asphalt driveway leading to Hobcaw
Yacht Club, 22.92 m (75.2 ft) SW of the SW corner of 132 Hobcaw Drive, 19.05 m
(62.5 ft) NW of a fire hydrant at the SE corner of the yacht club grounds, 17.98
m (59.0 ft) SSE of the corner of the yacht Club House, and 1.16 m (3.8 ft) east
of a 1.5-foot diameter pine tree.

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

                                                                                
Station ID: 8665192                         PUBLICATION DATE:  10/30/2003
Name:       WANDO RIVER ENTRANCE                              
            SC
NOAA Chart: 11524                           Latitude:   32° 49.3' N (  32.82170)
USGS Quad:  CHARLESTON                      Longitude:  79° 54.0' W ( -79.90000)


                            T I D A L   D A T U M S 


Tidal datums at WANDO RIVER ENTRANCE based on:

     LENGTH OF SERIES:      1 YEAR
     TIME PERIOD:           January 1977 - December 1977
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8665530 CHARLESTON, COOPER RIVER ENTRANCE


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

     HIGHEST OBSERVED WATER LEVEL (06/01/1977)         =  2.315
     MEAN HIGHER HIGH WATER                     MHHW   =  1.806
     MEAN HIGH WATER                            MHW    =  1.697
     North American Vertical Datum              NAVD88 =  0.971
     MEAN SEA LEVEL                             MSL    =  0.918
     MEAN TIDE LEVEL                            MTL    =  0.877
     MEAN LOW WATER                             MLW    =  0.056
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (12/21/1976)         = -0.721

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     5192 D 1976                                 4.339    2.642
     HOBCAW 2 1976                               2.769    1.072
     HOBCAW 3 1976                               3.928    2.231


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

                                                                                
Station ID: 8665192                         PUBLICATION DATE:  10/30/2003
Name:       WANDO RIVER ENTRANCE                              
            SC
NOAA Chart: 11524                           Latitude:   32° 49.3' N (  32.82170)
USGS Quad:  CHARLESTON                      Longitude:  79° 54.0' W ( -79.90000)


                             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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