Superseded Bench Mark Sheet for 8662299, CLAMBANK CREEK DOCK, GOAT ISLAND SC

Present Epoch

Printable version

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

                                                   PUBLICATION DATE:  09/19/1988
Station ID: 8662299                                SUPERCEDED DATE:   04/21/2003
Name:       CLAMBANK CREEK                                    
            SOUTH CAROLINA
NOAA Chart: 11532                                  Latitude:         33° 20.0' N
USGS Quad:  NORTH ISLAND                           Longitude:        79° 11.6' W


To reach the tidal bench marks from the east end of U.S. Highway 17 bridge over
Waccamaw River, proceed east on U.S. Highway 17 for 1.2 miles (1.9 km) to the
entrance to Hobcaw Barony, then south on the entrance road for about 80 feet (24
m) to an electric gate and telephone (dial 11 to obtain permission to enter),
continue south along a gravel road for 0.35 mile (0.56 km) to a three way
junction, then easterly for 0.4 mile (0.6 km) to a Y-junction, then SE for 1.8
miles (2.9 km) to the entrance to a marine laboratory, continue south for 1.1
miles (1.8 km) to a T-junction and 1.9 miles (3.1 km) southerly and northerly to
a lookout tower and a cinder block building on Goat Island.  The bench marks are
at the boat landing ramp and dock and at the lookout tower.  The tide gage and
staff were on the inside of the right angle dock.


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


                 PRIMARY BENCH MARK STAMPING:  2299 D 1976

MONUMENTATION:           Survey Disk                               VM#:     3924
AGENCY:                                                            PID#:  DD1355
SETTING CLASSIFICATION:  Copper-clad Steel Rod


The bench mark is along the dirt road between the dock and the lookout tower,
about 300 feet (91 m) NW of Bench Mark NO 2 1968, 144.5 feet (44.0 m) east of
the east leg of the lookout tower, 21.5 feet (6.6 m) SSE of a large cedar tree,
10.6 feet (3.2 m) NE of the centerline of the dirt road leading to the boat
landing ramp, and 3.0 feet (0.9 m) SW of a steel witness post with sign.  The
bench mark is 0.2 foot (0.1 m) above ground level, crimped to a copper- clad
steel rod driven 56 feet (17 m) to refusal, and encased in a 4-inch PVC pipe and
concrete kickblock.



                         BENCH MARK STAMPING:  2299 E 1976

MONUMENTATION:           Survey Disk                               VM#:     3925
AGENCY:                                                            PID#:  DD1354
SETTING CLASSIFICATION:  Concrete Footing


The bench mark is set in the east leg of the lookout tower, 144.5 feet (44.0 m)
SW of Bench Mark 2299 D 1976, 57.0 feet (17.4 m) south of the south corner of a
cinder block building, 6.0 feet (1.8 m) NNW of a cedar tree, 1.1 feet (0.3 m)
SSE of a metal witness post with sign, and 0.7 foot (0.2 m) above ground level.

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

                                                   PUBLICATION DATE:  09/19/1988
Station ID: 8662299                                SUPERCEDED DATE:   04/21/2003
Name:       CLAMBANK CREEK                                    
            SOUTH CAROLINA
NOAA Chart: 11532                                  Latitude:         33° 20.0' N
USGS Quad:  NORTH ISLAND                           Longitude:        79° 11.6' W


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


                         BENCH MARK STAMPING:  2299 F 1976

MONUMENTATION:           Survey Disk                               VM#:     3926
AGENCY:                                                            PID#:  DD1353
SETTING CLASSIFICATION:  Copper-clad Steel Rod


The bench mark is near a 3-foot (1 m) diameter lone oak tree WSW of the lookout
tower, 94.3 feet (28.7 m) south of the west corner of a cinder block building,
25.2 feet (7.7 m) west of the south leg of the lookout tower, 9.8 feet (3.0 m)
NNW of the lone oak tree, 9.2 feet (2.8 m) SE of the centerline of the dirt road
leading to the cinder block building, and 4.2 feet (1.3 m) NE of a witness sign
nailed to a tree.  The bench mark is crimped to a copper- clad steel rod driven
to an unspecified depth 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  4

                                                   PUBLICATION DATE:  09/19/1988
Station ID: 8662299                                SUPERCEDED DATE:   04/21/2003
Name:       CLAMBANK CREEK                                    
            SOUTH CAROLINA
NOAA Chart: 11532                                  Latitude:         33° 20.0' N
USGS Quad:  NORTH ISLAND                           Longitude:        79° 11.6' W


                            T I D A L   D A T U M S 


Tidal datums at CLAMBANK CREEK based on:

     LENGTH OF SERIES:      12 MONTHS
     TIME PERIOD:           MAY 1976 - APRIL 1977
     TIDAL EPOCH:           1960-1978
     CONTROL TIDE STATION:  8665530 CHARLESTON


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

     HIGHEST OBSERVED WATER LEVEL (06/01/1977)         =   7.11
     MEAN HIGHER HIGH WATER                     MHHW   =   5.27
     MEAN HIGH WATER                            MHW    =   4.94
     MEAN TIDE LEVEL                            MTL    =   2.57
     MEAN LOW WATER                             MLW    =   0.21
     MEAN LOWER LOW WATER                       MLLW   =   0.00
     LOWEST  OBSERVED WATER LEVEL (12/21/1976)         =  -2.27

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In FEET above:

     Stamping or Designation                    MLLW        MHW

     2299 D 1976                                 7.74      2.80
     2299 E 1976                                 8.76      3.82
     2299 F 1976                                 7.91      2.97


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

                                                   PUBLICATION DATE:  09/19/1988
Station ID: 8662299                                SUPERCEDED DATE:   04/21/2003
Name:       CLAMBANK CREEK                                    
            SOUTH CAROLINA
NOAA Chart: 11532                                  Latitude:         33° 20.0' N
USGS Quad:  NORTH ISLAND                           Longitude:        79° 11.6' 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 8662299 CLAMBANK CREEK DOCK, GOAT ISLAND, SC