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Datums Page Page 1 of 6
Station ID: 8662931 PUBLICATION DATE: 02/05/2004
Name: WACCAMAW RIVER ENTRANCE
SC
NOAA Chart: 11532 Latitude: 33° 22.0' N ( 33.36670)
USGS Quad: GEORGETOWN SOUTH Longitude: 79° 15.3' W ( -79.25500)
To reach the tidal bench marks from the intersection of U.S. Highways 17, 17A,
and 701 in Georgetown, proceed east on U.S. Highway 17 for 2.9 km (1.8 mi) to
the paved road leading to the old causeway. The bench marks are along U.S.
Highway 17 and the old causeway. The tide gage and staff were on a pier NE of
the U.S. Highway 17 bridge over Waccamaw River.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 2931 D 1976
DESIGNATION: 866 2931 D TIDAL
MONUMENTATION: Tidal Station disk VM#: 3964
AGENCY: National Ocean Survey (NOS) IDB PID#: DD0926
SETTING CLASSIFICATION: Concrete sidewalk OPUS PID:
LATITUDE: 33° 22.0' N ( 33.36670) LONGITUDE: 79° 15.5' W ( -79.25830)
The primary bench mark is a disk located in the sidewalk on the NW corner of the
U.S. Highway 17 bridge over Waccamaw River, 4.66 m (15.3 ft) east of the west
end of the bridge, 28.99 m (9.5 ft) NNE of the bridge median strip centerline,
and 0.21 m (0.7 ft) above the road.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 8662931 PUBLICATION DATE: 02/05/2004
Name: WACCAMAW RIVER ENTRANCE
SC
NOAA Chart: 11532 Latitude: 33° 22.0' N ( 33.36670)
USGS Quad: GEORGETOWN SOUTH Longitude: 79° 15.3' W ( -79.25500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: MIZZELL 1976
DESIGNATION: MIZZELL
MONUMENTATION: Survey disk VM#: 3965
AGENCY: U.S. Corps of Engineers (USE) IDB PID#: DD0927
SETTING CLASSIFICATION: Concrete sidewalk OPUS PID:
LATITUDE: 33° 22.0' N ( 33.36670) LONGITUDE: 79° 15.5' W ( -79.25830)
The bench mark is a disk located in the sidewalk on the SW corner of the U.S.
Highway 17 Bridge over Waccamaw River, 8.90 m (29.2 ft) SSW of the bridge median
strip centerline, 4.79 m (15.7 ft) east of the west end of the bridge, and 0.21
m (0.7 ft) above the road.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 8662931 PUBLICATION DATE: 02/05/2004
Name: WACCAMAW RIVER ENTRANCE
SC
NOAA Chart: 11532 Latitude: 33° 22.0' N ( 33.36670)
USGS Quad: GEORGETOWN SOUTH Longitude: 79° 15.3' W ( -79.25500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: T 147 1979
DESIGNATION: T 147
MONUMENTATION: Vertical Control disk VM#: 3966
AGENCY: U.S Coastal and Geodetic Survey
(USC&GS) IDB PID#: DD0923
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 33° 22.1' N ( 33.36830) LONGITUDE: 79° 16.4' W ( -79.27330)
The bench mark is a disk located near a guy wire pole at the junction of U.S.
Highway 17 and St. Jails Street, 1.3 km (0.8 m) west of the U.S. Highway 17
bridge over Waccamaw River, 25.51 m (83.7 ft) WNW of a power pole with six guy
wires, 19.90 m (65.3 ft) ESE of the extended centerline of St. Jails Street,
9.81 m (32.2 ft) NNE of the centerline of the southbound lane of U.S. Highway
17, and 1.49 m (4.9 ft) NE of guy wire pole #E8. The bench mark is at ground
level, crimped to the top of a stainless steel rod driven 6.1 m (20 ft), and
encased in a pipe.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 8662931 PUBLICATION DATE: 02/05/2004
Name: WACCAMAW RIVER ENTRANCE
SC
NOAA Chart: 11532 Latitude: 33° 22.0' N ( 33.36670)
USGS Quad: GEORGETOWN SOUTH Longitude: 79° 15.3' W ( -79.25500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: U 147 1979
DESIGNATION: U 147
MONUMENTATION: Vertical Control disk VM#: 3967
AGENCY: U.S Coastal and Geodetic Survey
(USC&GS) IDB PID#: DD0924
SETTING CLASSIFICATION: Concrete sidewalk OPUS PID#: DD0924
LATITUDE: 33° 22.0' N ( 33.36670) LONGITUDE: 79° 16.1' W ( -79.26830)
The bench mark is a disk located on the SW corner of the U.S. Highway 17 Bridge
over the Pee Dee and Black Rivers, 0.72 km (0.45 mi) west of the U.S. Highway 17
bridge over Waccamaw River, 11 m (35 ft) east of the SW end of the bridge, 9 m
(29 ft) south of the centerline of U.S. Highway 17, 0.3 m (1 ft) north of the
south concrete guard rail, and 0.3 m (1 ft) south of the north edge of the
sidewalk.
BENCH MARK STAMPING: 2931 B 1976
DESIGNATION: 866 2931 B TIDAL
MONUMENTATION: Tidal Station disk VM#: 17130
AGENCY: National Ocean Survey (NOS) IDB PID#: DD0928
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 33° 22.2' N ( 33.37000) LONGITUDE: 79° 15.5' W ( -79.25830)
The bench mark is a disk located near a triple trunk live oak tree in the SE
angle of a paved road running east-west, 12.1 m (39.7 ft) south of the center of
the east-west paved road, 9.63 m (31.6 ft) NE of the center of the paved road
leading north, 9.60 m (31.5 ft) WSW of the oak tree, and 0.35 m (1.1 ft) west of
a witness post. The bench mark is level with the paved road, crimped to the top
of a copper-clad steel rod driven 6.1 m (20 ft) to refusal and encased in a PVC
pipe with conrete kickblock. NOTE: A thorough search by National Geodetic Survey
revealed no evidence of the mark in 1992
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 8662931 PUBLICATION DATE: 02/05/2004
Name: WACCAMAW RIVER ENTRANCE
SC
NOAA Chart: 11532 Latitude: 33° 22.0' N ( 33.36670)
USGS Quad: GEORGETOWN SOUTH Longitude: 79° 15.3' W ( -79.25500)
T I D A L D A T U M S
Tidal datums at WACCAMAW RIVER ENTRANCE based on:
LENGTH OF SERIES: 1 YEAR
TIME PERIOD: October 1977 - September 1978
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8662746 WINYAH BAY, SOUTH ISLAND PLANTATION
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (02/09/1978) = 1.447
MEAN HIGHER HIGH WATER MHHW = 1.209
MEAN HIGH WATER MHW = 1.130
MEAN SEA LEVEL MSL = 0.606
MEAN TIDE LEVEL MTL = 0.581
North American Vertical Datum NAVD88 = 0.552
MEAN LOW WATER MLW = 0.032
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (02/22/1978) = -1.012
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
2931 D 1976 9.387 8.257
MIZZELL 1976 9.389 8.259
T 147 1979 2.860 1.730
U 147 1979 3.867 2.737
2931 B 1976 1.589 0.459
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 8662931 PUBLICATION DATE: 02/05/2004
Name: WACCAMAW RIVER ENTRANCE
SC
NOAA Chart: 11532 Latitude: 33° 22.0' N ( 33.36670)
USGS Quad: GEORGETOWN SOUTH Longitude: 79° 15.3' W ( -79.25500)
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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Station Location
Published bench mark
Unpublished bench mark