U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
Station ID: 8662299 PUBLICATION DATE: 02/05/2004
Name: CLAMBANK CREEK DOCK, GOAT ISLAND
SC
NOAA Chart: 11532 Latitude: 33° 20.0' N ( 33.33330)
USGS Quad: NORTH ISLAND Longitude: 79° 11.6' W ( -79.19330)
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 1.9 km (1.2 mi) to the
entrance to Hobcaw Barony, then turn and proceed south on the entrance road for
about 24 m (80 ft) to an electric gate and telephone (dial 11 to obtain
permission to enter), then continue south along a gravel road for 0.56 km (0.35
mi) to a three way junction, then proceed east for 0.6 km (0.4 mi) to a
Y-junction, then proceed SE for 2.9 km (1.8 mi) to the entrance to a marine
laboratory, continue south for 1.8 km (1.1 mi) to a T-junction and 3.1 km (1.9
mi) 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
DESIGNATION: 866 2299 D TIDAL
MONUMENTATION: Tidal Station disk VM#: 3924
AGENCY: National Ocean Survey (NOS) IDB PID#: DD1355
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID#: DD1355
LATITUDE: 33° 20.1' N ( 33.33500) LONGITUDE: 79° 11.6' W ( -79.19330)
The primary bench mark is a disk located along the dirt road between the dock
and the lookout tower, about 91 m (300 ft) NW of Bench Mark NO 2 1968, 44.04 m
(144.5 ft) east of the east leg of the lookout tower, 6.55 m (21.5 ft) SSE of a
large cedar tree, 3.23 m (10.6 ft) NE of the centerline of the dirt road leading
to the boat landing ramp, and 0.91 m (3.0 ft) SW of a steel witness post with
sign. The bench mark is 0.06 m (0.2 ft) above ground level, crimped to the top
of a copper clad steel rod driven 17.1 m (56 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: 8662299 PUBLICATION DATE: 02/05/2004
Name: CLAMBANK CREEK DOCK, GOAT ISLAND
SC
NOAA Chart: 11532 Latitude: 33° 20.0' N ( 33.33330)
USGS Quad: NORTH ISLAND Longitude: 79° 11.6' W ( -79.19330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 2299 E 1976
DESIGNATION: 866 2299 E TIDAL
MONUMENTATION: Tidal Station disk VM#: 3925
AGENCY: National Ocean Survey (NOS) IDB PID#: DD1354
SETTING CLASSIFICATION: Footing OPUS PID:
LATITUDE: 33° 20.1' N ( 33.33500) LONGITUDE: 79° 11.7' W ( -79.19500)
The bench mark is a disk set in the east leg of the lookout tower, 44.04 m
(144.5 ft) SW of Bench Mark 2299 D 1976, 17.37 m (57.0 ft) south of the south
corner of a cinder block building, 1.83 m (6.0 ft) NNW of a cedar tree, 0.34 m
(1.1 ft) SSE of a metal witness post with sign, and 0.21 m (0.7 ft) above ground
level.
BENCH MARK STAMPING: 2299 F 1976
DESIGNATION: 866 2299 F TIDAL
MONUMENTATION: Tidal Station disk VM#: 3926
AGENCY: National Ocean Survey (NOS) IDB PID#: DD1353
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 33° 20.1' N ( 33.33500) LONGITUDE: 79° 11.7' W ( -79.19500)
The bench mark is a disk located near a 1 m (3 ft) diameter lone oak tree WSW of
the lookout tower, 28.74 m (94.3 ft) south of the west corner of a cinder block
building, 7.68 m (25.2 ft) west of the south leg of the lookout tower, 2.99 m
(9.8 ft) NNW of the lone oak tree, 2.80 m (9.2 ft) SE of the centerline of the
dirt road leading to the cinder block building, and 1.28 m (4.2 ft) NE of a
witness sign nailed to a tree. The bench mark is crimped to the top of 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
Station ID: 8662299 PUBLICATION DATE: 02/05/2004
Name: CLAMBANK CREEK DOCK, GOAT ISLAND
SC
NOAA Chart: 11532 Latitude: 33° 20.0' N ( 33.33330)
USGS Quad: NORTH ISLAND Longitude: 79° 11.6' W ( -79.19330)
T I D A L D A T U M S
Tidal datums at CLAMBANK CREEK DOCK, GOAT ISLAND based on:
LENGTH OF SERIES: 1 YEAR
TIME PERIOD: May 1976 - April 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 (11/21/1976) = 2.040
MEAN HIGHER HIGH WATER MHHW = 1.596
MEAN HIGH WATER MHW = 1.489
North American Vertical Datum NAVD88 = 0.937
MEAN SEA LEVEL MSL = 0.828
MEAN TIDE LEVEL MTL = 0.774
MEAN LOW WATER MLW = 0.059
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (12/21/1976) = -0.776
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
2299 D 1976 2.278 0.789
2299 E 1976 2.588 1.099
2299 F 1976 2.331 0.842
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
Station ID: 8662299 PUBLICATION DATE: 02/05/2004
Name: CLAMBANK CREEK DOCK, GOAT ISLAND
SC
NOAA Chart: 11532 Latitude: 33° 20.0' N ( 33.33330)
USGS Quad: NORTH ISLAND Longitude: 79° 11.6' W ( -79.19330)
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.