U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 7
Station ID: 8665567 PUBLICATION DATE: 05/23/2003
Name: BEN SAWYER BRIDGE, IWW
SC
NOAA Chart: 11524 Latitude: 32° 46.4' N ( 32.77330)
USGS Quad: FORT MOULTRIE Longitude: 79° 50.5' W ( -79.84170)
To reach the tidal bench marks from the intersection of U.S. Highway 17 and
State Highway 703, proceed SE on State Highway 703 for 2.98 km (1.85 mi) to Ben
Sawyer Memorial Bridge; just before the bridge turn left onto a paved road
leading to the East Cooper Outboard Club property, follow the road for about 0.3
km (0.2 mi) to the Intracoastal Waterway and a dock. The bench marks are along
State Highway 703 and along the access road. The tide gage and staff were on
the dock about 183 m (600 ft) NE of the bridge.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 5567 A 1976
DESIGNATION: 866 5567 A TIDAL
MONUMENTATION: Tidal Station disk VM#: 4197
AGENCY: National Ocean Survey (NOS) IDB PID#: CJ0591
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 32° 46.5' N ( 32.77500) LONGITUDE: 79° 50.5' W ( -79.84170)
The primary bench mark is a disk set on the East Cooper Outboard Club property,
62 m (203 ft) NE of the NE corner of the clubhouse, 4.02 m (13.2 ft) WSW of a 1
m (3 ft) diameter pine tree, and 1.46 m (4.8 ft) SE of power pole #91562 with
two guy wires. The bench mark is level with the ground, crimped to a
copper-clad steel rod driven 12.2 m (40 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 2 of 7
Station ID: 8665567 PUBLICATION DATE: 05/23/2003
Name: BEN SAWYER BRIDGE, IWW
SC
NOAA Chart: 11524 Latitude: 32° 46.4' N ( 32.77330)
USGS Quad: FORT MOULTRIE Longitude: 79° 50.5' W ( -79.84170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: PLEASANT 1942
DESIGNATION: PLEASANT
MONUMENTATION: Triangulation Station disk VM#: 4194
AGENCY: US Coast and Geodetic Survey
(USC&GC) IDB PID#: CJ0167
SETTING CLASSIFICATION: Concrete monument OPUS PID#: CJ0167
LATITUDE: 32° 47.2' N ( 32.78670) LONGITUDE: 79° 51.0' W ( -79.85000)
The bench mark is a disk set in the top of a concrete monument between the
highway and the marsh, 20.97 m (68.8 ft) NNW of power pole #21418 with two guy
wires and a street light, 20 m (66 ft) SSE of bench mark PLEASANT NO 1 1942,
10.03 m (32.9 ft) ENE of the centerline of the highway, 0.91 m (3.0 ft) WSW of a
wooden post, and 0.12 m (0.4 ft) above the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 7
Station ID: 8665567 PUBLICATION DATE: 05/23/2003
Name: BEN SAWYER BRIDGE, IWW
SC
NOAA Chart: 11524 Latitude: 32° 46.4' N ( 32.77330)
USGS Quad: FORT MOULTRIE Longitude: 79° 50.5' W ( -79.84170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: PLEASANT NO 1 1942
DESIGNATION: PLEASANT RM 1
MONUMENTATION: Reference Mark disk VM#: 4195
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: CJ0168
SETTING CLASSIFICATION: Concrete monument OPUS PID#: CJ0168
LATITUDE: 32° 47.2' N ( 32.78670) LONGITUDE: 79° 51.0' W ( -79.85000)
The bench mark is a disk set in the top of a concrete monument between the
highway and the marsh, 32.46 m (106.5 ft) SSW of the south anchor for a large TV
mast, 20.42 m (67.0 ft) SSE of power pole #116233 with three guy wires, 10 m (33
ft) ENE of the centerline of the highway, 0.49 m (1.6 ft) SSW of a witness post,
and 0.06 m (0.2 ft) above the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 7
Station ID: 8665567 PUBLICATION DATE: 05/23/2003
Name: BEN SAWYER BRIDGE, IWW
SC
NOAA Chart: 11524 Latitude: 32° 46.4' N ( 32.77330)
USGS Quad: FORT MOULTRIE Longitude: 79° 50.5' W ( -79.84170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: X 70 1952
DESIGNATION: X 70
MONUMENTATION: Bench Mark disk VM#: 4196
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: CJ0165
SETTING CLASSIFICATION: Bridge abutment OPUS PID:
LATITUDE: 32° 46.4' N ( 32.77330) LONGITUDE: 79° 50.5' W ( -79.84170)
The bench mark is a disk set in the NW abutment of Ben Sawyer Memorial Bridge, 5
m (18 ft) SW of the centerline of the highway, 1 m (2 ft) west of a concrete and
steel banister, and 0.15 m (0.5 ft) above the highway.
BENCH MARK STAMPING: 5567 B 1976
DESIGNATION: 866 5567 B TIDAL
MONUMENTATION: Tidal Station disk VM#: 4198
AGENCY: National Ocean Survey (NOS) IDB PID#: CJ0590
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 32° 46.5' N ( 32.77500) LONGITUDE: 79° 50.5' W ( -79.84170)
The bench mark is a disk set at the entrance gate to the East Cooper Outboard
Club property, 51.51 m (169.0 ft) NE of the centerline of the highway, 4 m (13
ft) SE of the centerline of the driveway, 0.55 m (1.8 ft) NW of a witness post,
and 0.37 m (1.2 ft) ESE of the north corner of a concrete block pillar. The
bench mark is level with the ground, crimped to a copper-clad steel rod driven
12.2 m (40 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 7
Station ID: 8665567 PUBLICATION DATE: 05/23/2003
Name: BEN SAWYER BRIDGE, IWW
SC
NOAA Chart: 11524 Latitude: 32° 46.4' N ( 32.77330)
USGS Quad: FORT MOULTRIE Longitude: 79° 50.5' W ( -79.84170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 5567 C 1976
DESIGNATION: 866 5567 C TIDAL
MONUMENTATION: Tidal Station disk VM#: 4199
AGENCY: National Ocean Survey (NOS) IDB PID#: CJ0589
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 32° 46.8' N ( 32.78000) LONGITUDE: 79° 50.8' W ( -79.84670)
The bench mark is a disk set on the east side of State Highway 703, 0.72 km
(0.45 mi) NW of the NW end of Ben Sawyer Memorial Bridge, 8.44 m (27.7 ft) ENE
of the centerline of the highway, 5.91 m (19.4 ft) west of power pole #21429,
2.19 m (7.2 ft) NW of the SW anchor of a guy wire, and 0.49 m (1.6 ft) ENE of a
witness post. The bench mark is level with the ground, crimped to a copper-clad
steel rod driven 12.2 m (40 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 6 of 7
Station ID: 8665567 PUBLICATION DATE: 05/23/2003
Name: BEN SAWYER BRIDGE, IWW
SC
NOAA Chart: 11524 Latitude: 32° 46.4' N ( 32.77330)
USGS Quad: FORT MOULTRIE Longitude: 79° 50.5' W ( -79.84170)
T I D A L D A T U M S
Tidal datums at BEN SAWYER BRIDGE, IWW based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: July 1976 - September 1976
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:
MEAN HIGHER HIGH WATER MHHW = 1.710
MEAN HIGH WATER MHW = 1.596
North American Vertical Datum NAVD88 = 0.963
MEAN SEA LEVEL MSL = 0.853
MEAN TIDE LEVEL MTL = 0.826
MEAN LOW WATER MLW = 0.057
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
5567 A 1976 2.434 0.838
PLEASANT 1942 2.573 0.977
PLEASANT NO 1 1942 2.613 1.017
X 70 1952 9.018 7.422
5567 B 1976 2.359 0.763
5567 C 1976 2.814 1.218
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 7
Station ID: 8665567 PUBLICATION DATE: 05/23/2003
Name: BEN SAWYER BRIDGE, IWW
SC
NOAA Chart: 11524 Latitude: 32° 46.4' N ( 32.77330)
USGS Quad: FORT MOULTRIE Longitude: 79° 50.5' W ( -79.84170)
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.