U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 6
Station ID: 8667062 PUBLICATION DATE: 02/05/2004
Name: KIAWAH BRIDGE, KIAWAH RIVER
SOUTH CAROLINA
NOAA Chart: 11522 Latitude: 32° 36.2' N
USGS Quad: ROCKVILLE Longitude: 80° 7.9' W
To reach the tidal bench marks from the intersection of U.S. Highway 17 and
State Highway S-10-20 (Main Road) west of Charleston, proceed south on State
Highway S-10-20 for 27.0 km (16.8 mi) to the fork in the road at the entrance to
Kiawah Island and Seabrook Island, then turn left onto Kiawah Island Parkway and
continue for 2.6 km (1.6 mi) to the wood bridge over Kiawah River. The bench
marks are along the road near the bridge. The tide gauge and staff were on a
platform beneath the bridge.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 7062 B 1977
DESIGNATION: 866 7062 B TIDAL
MONUMENTATION: Tidal Station disk VM#: 11492
AGENCY: National Ocean Survey (NOS) PID#: CK2678
SETTING CLASSIFICATION: Galvanized steel rod
The primary bench mark is a disk located in the high marsh area north of the
road leading to the bridge, 94.64 m (310.5 ft) NNW of the NE corner of the
bridge, 34.78 m (114.1 ft) NE of the centerline of the road, and 0.58 m (1.9 ft)
WSW of a metal witness post. The bench mark is set at ground level, crimped to
the top of a galvanized steel rod driven 12.2 m (40 ft) to refusal, and encased
in a PVC pipe and a concrete kickblock.
BENCH MARK STAMPING: 7062 C 1977
DESIGNATION: 866 7062 C TIDAL
MONUMENTATION: Tidal Station disk VM#: 11493
AGENCY: National Ocean Survey (NOS) PID:
SETTING CLASSIFICATION: Concrete monument
The bench mark is a disk set in the top of a concrete monument on the north side
of the road next to a palmetto tree, 134.4 m (441.0 ft) NW of the NE corner of
the bridge, 54.41 m (178.5 ft) WNW of bench mark 7062 B 1977, 12.86 m (42.2 ft)
NE of the centerline of the road, 1.13 m (3.7 ft) west of a metal witness post,
0.52 m (1.7 ft) SSW of the palmetto tree, and level with the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 8667062 PUBLICATION DATE: 02/05/2004
Name: KIAWAH BRIDGE, KIAWAH RIVER
SOUTH CAROLINA
NOAA Chart: 11522 Latitude: 32° 36.2' N
USGS Quad: ROCKVILLE Longitude: 80° 7.9' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 7062 D 1978
DESIGNATION: 866 7062 D TIDAL
MONUMENTATION: Tidal Station disk VM#: 11494
AGENCY: National Ocean Survey (NOS) PID:
SETTING CLASSIFICATION: Concrete monument
The bench mark is a disk set in the top of a concrete monument on the NE side of
the road, south of the bridge, 35.14 m (115.3 ft) SE of the SW corner of the
bridge, 34.38 m (112.8 ft) SE of the SE corner of the bridge, 4.57 m (15.0 ft)
NE of the centerline of the road, 2.19 m (7.2 ft) SE of the most southeastern
guard post, and level with the ground.
BENCH MARK STAMPING: 7062 E 1978
DESIGNATION: 866 7062 E TIDAL
MONUMENTATION: Tidal Station disk VM#: 11495
AGENCY: National Ocean Survey (NOS) PID:
SETTING CLASSIFICATION: Galvanized steel rod
The bench mark is a disk located on the NE side of the road, south of the
bridge, 67.06 m (222.0 ft) SE of bench mark 7062 D 1978, 12.59 m (41.3 ft) SE of
a Narrow Bridge sign, 7.80 m (25.6 ft) SE of a telephone cable junction box, and
7.68 m (25.2 ft) NE of the centerline of the road. The bench mark is set at
ground level, crimped to the top of a galvanized steel rod driven 11.6 m (38 ft)
to refusal, and encased in a PVC pipe and a concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 8667062 PUBLICATION DATE: 02/05/2004
Name: KIAWAH BRIDGE, KIAWAH RIVER
SOUTH CAROLINA
NOAA Chart: 11522 Latitude: 32° 36.2' N
USGS Quad: ROCKVILLE Longitude: 80° 7.9' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 7062 F 1984
DESIGNATION: 866 7062 F TIDAL
MONUMENTATION: Tidal Station disk VM#: 11496
AGENCY: National Ocean Service (NOS) PID#: CK2677
SETTING CLASSIFICATION: Concrete monument
The bench mark is a disk set in the top of a concrete monument near a lone
palmetto tree at the edge of the marsh, on the outside of a curve of the road
leading to the bridge, 68.73 m (225.5 ft) ESE of bench mark 7062 G 1984, 50.23 m
(164.8 ft) west of bench mark 7062 B 1977, 13.01 m (42.7 ft) NNE of the
centerline of the road, 4.42 m (14.5 ft) ESE of the palmetto tree, and level
with the ground.
BENCH MARK STAMPING: 7062 G 1984
DESIGNATION: 866 7062 G TIDAL
MONUMENTATION: Tidal Station disk VM#: 11497
AGENCY: National Ocean Service (NOS) PID#: CK2676
SETTING CLASSIFICATION: Concrete monument
The bench mark is a disk set in the top of a concrete monument across the road
from a lone 0.61 m (2.0 ft) diameter palmetto tree, 61 m (200 ft) ENE of bench
mark 7062 H 1984, 23.56 m (77.3 ft) NNE of the long palmetto tree across the
road, 2.99 m (9.8 ft) SW of a 0.18 m (0.6 ft) pine tree, and level with the
ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 8667062 PUBLICATION DATE: 02/05/2004
Name: KIAWAH BRIDGE, KIAWAH RIVER
SOUTH CAROLINA
NOAA Chart: 11522 Latitude: 32° 36.2' N
USGS Quad: ROCKVILLE Longitude: 80° 7.9' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 7062 H 1984
DESIGNATION: 866 7062 H TIDAL
MONUMENTATION: Tidal Station disk VM#: 11498
AGENCY: National Ocean Service (NOS) PID#: CK2675
SETTING CLASSIFICATION: Stainless steel rod
The bench mark is a disk located before a curve in the road leading to the
bridge, 9.30 m (30.5 ft) west of a multi-trunk oak tree, 8.53 m (28.0 ft) SE of
the centerline of the road, and 2.19 m (7.2 ft) NW of a wire fence. The bench
mark is set level with the ground, crimped to the top of a stainless steel rod
driven 14.6 m (48 ft) to refusal, and encased in a PVC pipe and concrete
kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 8667062 PUBLICATION DATE: 02/05/2004
Name: KIAWAH BRIDGE, KIAWAH RIVER
SOUTH CAROLINA
NOAA Chart: 11522 Latitude: 32° 36.2' N
USGS Quad: ROCKVILLE Longitude: 80° 7.9' W
T I D A L D A T U M S
Tidal datums at KIAWAH BRIDGE, KIAWAH RIVER based on:
LENGTH OF SERIES: 1 YEAR
TIME PERIOD: May 1977 - April 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 (06/02/1977) = 2.412
MEAN HIGHER HIGH WATER (MHHW) = 1.877
MEAN HIGH WATER (MHW) = 1.758
NORTH AMERICAN VERTICAL DATUM-1988 (NAVD) = 0.998
MEAN SEA LEVEL (MSL) = 0.939
MEAN TIDE LEVEL (MTL) = 0.905
MEAN LOW WATER (MLW) = 0.052
MEAN LOWER LOW WATER (MLLW) = 0.000
LOWEST OBSERVED WATER LEVEL (04/06/1977) = -0.642
National Geodetic Vertical Datum (NGVD 29)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
7062 B 1977 2.044 0.286
7062 C 1977 2.627 0.869
7062 D 1978 4.044 2.286
7062 E 1978 3.107 1.349
7062 F 1984 2.448 0.690
7062 G 1984 2.278 0.520
7062 H 1984 2.176 0.418
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 8667062 PUBLICATION DATE: 02/05/2004
Name: KIAWAH BRIDGE, KIAWAH RIVER
SOUTH CAROLINA
NOAA Chart: 11522 Latitude: 32° 36.2' N
USGS Quad: ROCKVILLE Longitude: 80° 7.9' 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 (NAVD 88).
NGVD 29 is a fixed datum adopted as a national standard geodetic reference for
heights but is now considered superseded. NGVD 29 is sometimes referred to as
Sea Level Datum of 1929 or as Mean Sea Level on some early issues of Geological
Survey Topographic Quads. NGVD 29 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 NGVD 29 are available from the National
Geodetic Survey (NGS) data base via the World Wide Web at
National Geodetic Survey.
NAVD 88 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. NAVD 88 replaces NGVD 29 as the national
standard geodetic reference for heights. Bench mark elevations relative to
NAVD 88 are available from NGS through the World Wide Web at
National Geodetic Survey.
NGVD 29 and NAVD 88 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 NAVD 88 elevation is shown on the Elevations of Tidal Datums Table Referred
to MLLW only when two or more of the bench marks listed have NAVD 88 elevations.
The NAVD 88 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, NAVD 88 bench mark elevations computed indirectly from the tidal
datums elevation table may differ slightly from NAVD 88 elevations listed for
each bench mark in the NGS database.