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Bench Mark Sheet for 8661419, GARDEN CITY BRIDGE, MURRELLS INLET 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Superseded Epoch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Small blue map location marker Unpublished bench mark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: 8661419                         PUBLICATION DATE:  02/13/2004
Name:       GARDEN CITY BRRIDGE, MURRELLS INLET               
            SC
NOAA Chart: 11535                           Latitude:   33° 34.7' N (  33.57830)
USGS Quad:  BROOKGREEN                      Longitude:  79°  0.2' W ( -79.00330)


To reach the tidal bench marks from the intersection of U.S. Highway 17 South
and Atlantic Avenue, proceed SE on Atlantic Avenue for 1.0 km (0.6 mi), towards
Garden City Beach and the bridge over Main Creek.  The bench marks are along the
road NW of the bridge.  The tide gage and staff were on the SW side of the
bridge near the NW end.


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


                 PRIMARY BENCH MARK STAMPING:  GCB NO 1 1975
                         DESIGNATION:          866 1419 TIDAL GCB 1

MONUMENTATION:           Tidal Station disk                    VM#:         3766
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  DD1494
SETTING CLASSIFICATION:  Copper-clad steel rod                 OPUS PID:        
LATITUDE:   33° 34.8' N (  33.58000)          LONGITUDE:  79°  0.2' W ( -79.00330)


The primary bench mark is a disk located about 91 m (300 ft) NW of the NW end of
the bridge over Main Creek, 9.60 m (31.5 ft) NE of the centerline of the
highway, 5.30 m (17.4 ft) SE of the center of the last driveway before reaching
the bridge on the NE side of the highway, 1.10 m (3.6 ft) east of utility pole
#1C-17-1-D, and 0.82 m (2.7 ft) west of a steel witness post.  The bench mark is
0.03 m (0.1 ft) below ground level, crimped to the top of a copper-clad steel
rod driven 14.6 m (48 ft) to refusal, and encased in a 5-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: 8661419                         PUBLICATION DATE:  02/13/2004
Name:       GARDEN CITY BRRIDGE, MURRELLS INLET               
            SC
NOAA Chart: 11535                           Latitude:   33° 34.7' N (  33.57830)
USGS Quad:  BROOKGREEN                      Longitude:  79°  0.2' W ( -79.00330)


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


                         BENCH MARK STAMPING:  GCB NO 2 1975
                         DESIGNATION:          866 1419 TIDAL GCB 2

MONUMENTATION:           Tidal Station disk                    VM#:         3767
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  DD1493
SETTING CLASSIFICATION:  Copper-clad steel rod                 OPUS PID:        
LATITUDE:   33° 34.9' N (  33.58170)          LONGITUDE:  79°  0.3' W ( -79.00500)


The bench mark is a disk located about 105 m (345 ft) NW of Bench Mark GCB NO 1
1975, 8.20 m (26.9 ft) NE of the centerline of the highway, 2.07 m (6.8 ft) west
of a 0.24 m (0.8 ft) diameter pine tree, 1.07 m (3.5 ft) north of utility pole
#1C-17-1-C, and 0.70 m (2.3 ft) NE of a steel witness post.  The bench mark is
0.03 m (0.1 ft) below 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.



                         BENCH MARK STAMPING:  GCB NO 3 1975
                         DESIGNATION:          866 1419 TIDAL GCB 3

MONUMENTATION:           Tidal Station disk                    VM#:         3768
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  DD1492
SETTING CLASSIFICATION:  Copper-clad steel rod                 OPUS PID:        
LATITUDE:   33° 34.9' N (  33.58170)          LONGITUDE:  79°  0.4' W ( -79.00670)


The bench mark is a disk located about 165 m (540 ft) NW of Bench Mark GCB NO 2
1975, 25.15 m (82.5 ft) NW of the centerline of West Canal Drive, 8.44 m (27.7
ft) SW of the centerline of the highway, 5.12 m (16.8 ft) NE of underground
telephone cable junction box #1C-5, and 1.46 m (4.8 ft) SE of utility pole #6
1/4 B.  The bench mark is 0.03 m (0.1 ft) below ground level, crimped to the top
of a copper-clad steel rod driven 13.7 m (45 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: 8661419                         PUBLICATION DATE:  02/13/2004
Name:       GARDEN CITY BRRIDGE, MURRELLS INLET               
            SC
NOAA Chart: 11535                           Latitude:   33° 34.7' N (  33.57830)
USGS Quad:  BROOKGREEN                      Longitude:  79°  0.2' W ( -79.00330)


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


                         BENCH MARK STAMPING:  GCB NO 4 1975
                         DESIGNATION:          866 1419 TIDAL GCB 4

MONUMENTATION:           Tidal Station disk                    VM#:         3769
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  DD1491
SETTING CLASSIFICATION:  Copper-clad steel rod                 OPUS PID:        
LATITUDE:   33° 35.0' N (  33.58330)          LONGITUDE:  79°  0.5' W ( -79.00830)


The bench mark is a disk located about 114 m (375 ft) NW of Bench Mark GCB NO 3
1975, 9.66 m (31.7 ft) SW of the centerline of the highway, 9.42 m (30.9 ft) NW
of the centerline of East Bank Road, 6 m (20 ft) north of a lighted brick fence
post on the north side of East Bank Road, and 0.98 m (3.2 ft) west of utility
pole #B 5 1/2.  The bench mark is 0.03 m (0.1 ft) below 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.



                         BENCH MARK STAMPING:  GCB NO 5 1975
                         DESIGNATION:          866 1419 TIDAL GCB 5

MONUMENTATION:           Tidal Station disk                    VM#:         3770
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  DD1490
SETTING CLASSIFICATION:  Copper-clad steel rod                 OPUS PID:        
LATITUDE:   33° 35.0' N (  33.58330)          LONGITUDE:  79°  0.5' W ( -79.00830)


The bench mark is a disk located about 101 m (330 ft) NW of Bench Mark GCB NO 4
1975, 9.48 m (31.1 ft) NW of the centerline of Clubhouse Road, 8.99 m (29.5 ft)
SW of the centerline of the highway, 3.32 m (10.9 ft) NW of a 1 m (4 ft) high
lighted brick fence post on the north side of Clubhouse Road, and 0.52 m (1.7
ft) from the first brick fence post north of the lighted post.  The bench mark
is 0.03 m (0.1 ft) below 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  4 of  5

                                                                                
Station ID: 8661419                         PUBLICATION DATE:  02/13/2004
Name:       GARDEN CITY BRRIDGE, MURRELLS INLET               
            SC
NOAA Chart: 11535                           Latitude:   33° 34.7' N (  33.57830)
USGS Quad:  BROOKGREEN                      Longitude:  79°  0.2' W ( -79.00330)


                            T I D A L   D A T U M S 


Tidal datums at GARDEN CITY BRRIDGE, MURRELLS INLET based on:

     LENGTH OF SERIES:      1 YEAR
     TIME PERIOD:           December 1974 - November 1975
     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 (06/10/1975)         =  2.015
     MEAN HIGHER HIGH WATER                     MHHW   =  1.457
     MEAN HIGH WATER                            MHW    =  1.336
     North American Vertical Datum              NAVD88 =  0.803
     MEAN SEA LEVEL                             MSL    =  0.696
     MEAN TIDE LEVEL                            MTL    =  0.687
     MEAN LOW WATER                             MLW    =  0.038
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (11/22/1975)         = -0.191

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     GCB NO 1 1975                               2.674    1.338
     GCB NO 2 1975                               3.003    1.667
     GCB NO 3 1975                               4.066    2.730
     GCB NO 4 1975                               4.340    3.004
     GCB NO 5 1975                               5.173    3.837


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

                                                                                
Station ID: 8661419                         PUBLICATION DATE:  02/13/2004
Name:       GARDEN CITY BRRIDGE, MURRELLS INLET               
            SC
NOAA Chart: 11535                           Latitude:   33° 34.7' N (  33.57830)
USGS Quad:  BROOKGREEN                      Longitude:  79°  0.2' W ( -79.00330)


                             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 8661419 GARDEN CITY BRIDGE, MURRELLS INLET, SC

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