U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8666367 PUBLICATION DATE: 02/05/2004
Name: WILLTOWN BLUFF
SC
NOAA Chart: 11521 Latitude: 32° 40.9' N ( 32.68170)
USGS Quad: FENWICK Longitude: 80° 25.0' W ( -80.41670)
To reach the tidal bench marks from the intersection of U.S. Highway 17 and
State Highway 162, proceed SW on State Highway 162 for 17.9 km (11.1 mi) to the
intersection with State Highway 164, then bear left and continue SW on State
Highway 164 for 3.9 km (2.4 mi) to the intersection with State Highway 174 and
proceed straight through the intersection to continue SW on Willtown Road for
5.1 km (3.2 mi) to the end of the pavement, then continue on the dirt road for
1.6 km (1.0 mi) to County Road S-10-38, then bear left past the entrance to
Hutton Plantation and travel 0.5 km (0.3 mi), then bear right into Willtown
Bluff and travel 0.3 km (0.2 mi) to a fork in the road, then veer left and
continue down the dirt driveway to a house and sheds. The bench marks are along
the driveway. The tide gage and staff were behind the second house on a pier at
the bottom of the bluff.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 6367 C 1977
DESIGNATION: 866 6367 C TIDAL
MONUMENTATION: Tidal Station disk VM#: 4302
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 32° 40.9' N ( 32.68170) LONGITUDE: 80° 25.0' W ( -80.41670)
The primary bench mark is a disk located behind the second house, 30.18 m (99.0
ft) WSW of an old concrete column, 11 m (36 ft) NE of an oak tree by the steps
leading to the gage, 3.81 m (12.5 ft) NNW of the corner of the sun porch, and
3.05 m (10 ft) east of a 1 m (3 ft) diameter magnolia tree. The bench mark is
at ground level, crimped to the top of a copper-clad steel rod driven 7.3 m (24
ft) to refusal, encased in a PVC pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8666367 PUBLICATION DATE: 02/05/2004
Name: WILLTOWN BLUFF
SC
NOAA Chart: 11521 Latitude: 32° 40.9' N ( 32.68170)
USGS Quad: FENWICK Longitude: 80° 25.0' W ( -80.41670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6367 D 1977
DESIGNATION: 866 6367 D TIDAL
MONUMENTATION: Tidal Station disk VM#: 4303
AGENCY: National Ocean Survey (NOS) IDB PID#: CK2481
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 32° 40.9' N ( 32.68170) LONGITUDE: 80° 24.9' W ( -80.41500)
The bench mark is a disk located near a 5.09 m (16.7 ft) oak tree in the
meadian of the dirt road leading to the Lane residence, 48.77 m (160.0 ft) NNE
of the NE corner of the house, 35.91 m (117.8 ft) SSW of a sun dial, and 3.35 m
(11.0 ft) east of a 5.09 m (16.7 ft) oak tree. The bench mark is set at ground
level, crimped to the top of a copper-clad steel rod driven 6.1 m (20 ft) to
refusal, encased in a PVC pipe and concrete kickblock.
BENCH MARK STAMPING: 6367 E 1977
DESIGNATION: 866 6367 E TIDAL
MONUMENTATION: Tidal Station disk VM#: 4304
AGENCY: National Ocean Survey (NOS) IDB PID#: CK2480
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 32° 40.9' N ( 32.68170) LONGITUDE: 80° 24.9' W ( -80.41500)
The bench mark is a disk located near the road leading to the boat ramp, 78.88 m
(258.8 ft) ENE of bench mark 866 6367 D, 11.43 m (37.5 ft) NW of the approximate
center of the X-intersection, and 8.53 m (28.0 ft) SE of the 2.53 m (8.3 ft) oak
tree. The bench mark is set at ground level, crimped to the top of a copper-clad
steel rod driven 8.2 m (27 ft) to refusal, encased in a PVC pipe and concrete
kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8666367 PUBLICATION DATE: 02/05/2004
Name: WILLTOWN BLUFF
SC
NOAA Chart: 11521 Latitude: 32° 40.9' N ( 32.68170)
USGS Quad: FENWICK Longitude: 80° 25.0' W ( -80.41670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 4 1974
DESIGNATION: 866 6367 TIDAL 4
MONUMENTATION: Tidal Station disk VM#: 4305
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete driveway OPUS PID:
LATITUDE: 32° 40.9' N ( 32.68170) LONGITUDE: 80° 25.0' W ( -80.41670)
The bench mark is a disk set flush in a concrete driveway near the SE corner of
a garage, 21.64 m (71.0 ft) WNW of a 2 m (5 ft) diameter triple forked oak tree,
15.94 m (52.3 ft) SSW of bench mark NO 5 1974, 12.71 m (41.7 ft) ESE of the edge
of the driveway for the garage, and 8.84 m (29.0 ft) south of a 1 m (3 ft)
diameter oak tree.
BENCH MARK STAMPING: NO 5 1974
DESIGNATION: 866 6367 TIDAL 5
MONUMENTATION: Tidal Station disk VM#: 4306
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 32° 40.9' N ( 32.68170) LONGITUDE: 80° 25.0' W ( -80.41670)
The bench mark is a disk set flush in a concrete monument near an old gasoline
pump behind the garage, 15.94 m (52.3 ft) NNW of bench mark NO 4 1974, 11.28 m
(37.0 ft) WNW of a 1 m (3 ft) diameter oak tree, 9.08 m (29.8 ft) NE of the NE
corner of the garage, and 1.22 m (4.0 ft) east of the gas pump.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8666367 PUBLICATION DATE: 02/05/2004
Name: WILLTOWN BLUFF
SC
NOAA Chart: 11521 Latitude: 32° 40.9' N ( 32.68170)
USGS Quad: FENWICK Longitude: 80° 25.0' W ( -80.41670)
T I D A L D A T U M S
Tidal datums at WILLTOWN BLUFF based on:
LENGTH OF SERIES: 1 YEAR
TIME PERIOD: June 1977 - May 1978
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) = 2.275
MEAN HIGHER HIGH WATER MHHW = 1.882
MEAN HIGH WATER MHW = 1.795
MEAN SEA LEVEL MSL = 1.054
MEAN TIDE LEVEL MTL = 0.931
North American Vertical Datum NAVD88 = 0.899
MEAN LOW WATER MLW = 0.067
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (01/25/1979) = -0.874
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
6367 C 1977 8.752 6.957
6367 D 1977 10.016 8.221
6367 E 1977 9.405 7.610
NO 4 1974 9.814 8.019
NO 5 1974 9.781 7.986
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8666367 PUBLICATION DATE: 02/05/2004
Name: WILLTOWN BLUFF
SC
NOAA Chart: 11521 Latitude: 32° 40.9' N ( 32.68170)
USGS Quad: FENWICK Longitude: 80° 25.0' W ( -80.41670)
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.