U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
Station ID: 8661989 PUBLICATION DATE: 08/03/2004
Name: BENNETT'S DOCK
SC
NOAA Chart: 11535 Latitude: 33° 26.1' N ( 33.43500)
USGS Quad: WAVERLY MILLS Longitude: 79° 7.6' W ( -79.12670)
To reach the tidal bench marks from the intersection of U.S. Highway 17 and
State Road 46, proceed SE on State Road 46 (North Causeway Road) for 0.56 km
(0.35 mi) to the bridge over Pawleys Island Creek. The bench marks are on the
bridge and along State Road 46. The tide gage and staff were located about 0.2
km (0.1 mi) NW of the bridge on a dock owned by the Bennett family.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: BD NO 1 1975
DESIGNATION: 866 1989 TIDAL BD 1
MONUMENTATION: Tidal Station disk VM#: 3901
AGENCY: National Ocean Survey (NOS) IDB PID#: DD1411
SETTING CLASSIFICATION: Copper clad steel rod OPUS PID:
LATITUDE: 33° 26.2' N ( 33.43670) LONGITUDE: 79° 7.5' W ( -79.12500)
The bench mark is a disk located across the dirt road from the Bennett house, 82
m (270 ft) west of State Road 46, 23.99 m (78.7 ft) NW of the NW corner of
Clayer and Littlejon house, 15.36 m (50.4 ft) SW of a 0.61 m (2.0 ft) diameter
oak tree, 5.43 m (17.8 ft) south of the centerline of the dirt road, and 0.49 m
(1.6 ft) south of utility pole # AD5. The bench mark is set 12 cm (0.4 ft)
below ground level, in concrete atop a steel rod driven to refusal.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
Station ID: 8661989 PUBLICATION DATE: 08/03/2004
Name: BENNETT'S DOCK
SC
NOAA Chart: 11535 Latitude: 33° 26.1' N ( 33.43500)
USGS Quad: WAVERLY MILLS Longitude: 79° 7.6' W ( -79.12670)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: BD NO 2 1975
DESIGNATION: 866 1989 TIDAL BD 2
MONUMENTATION: Tidal Station disk VM#: 3902
AGENCY: National Ocean Survey (NOS) IDB PID#: DD1404
SETTING CLASSIFICATION: Abandoned concrete foundation OPUS PID:
LATITUDE: 33° 26.3' N ( 33.43830) LONGITUDE: 79° 7.5' W ( -79.12500)
The bench mark is a disk set in an abandoned concrete foundation (formerly for a
television tower) in the SW corner of Edward P. Mills property, about 110 m (360
ft) NW of bench mark BD NO 1 1975, 16.61 m (54.5 ft) east of the centerline of
the drive leading to Mills residence, 15.61 m (51.2 ft) WSW of the south corner
of the house, 10.15 m (33.3 ft) SSE of the west corner of the house, 9.81 m
(32.2 ft) NW of utility pole No. 74376, 0.2 m (0.7 ft) SW of a witness post, and
0.02 m (0.07 ft) above the ground.
BENCH MARK STAMPING: 1989 G 1982
DESIGNATION: 866 1989 G TIDAL
MONUMENTATION: Tidal Station disk VM#: 3903
AGENCY: National Ocean Survey (NOS) IDB PID#: DD1410
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 33° 26.2' N ( 33.43670) LONGITUDE: 79° 7.5' W ( -79.12500)
The bench mark is a disk located on the east side of State Road 46 north of the
bridge, 17.01 m (55.8 ft) ENE of the centerline of the road, 13.81 m (45.3 ft)
SSW of the SW corner of a house, 5.49 m (18.0 ft) east of the easternmost gate
post for an asphalt drive to a two story wooden house, 5.18 m (17.0 ft) north of
the centerline of the drive to Rosa's residence, and 0.98 m (3.2 ft) SE of
utility pole #23487. The bench mark is crimped to the top of a stainless steel
rod driven 7.3 m (24 ft) to refusal and encased in a 5-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: 8661989 PUBLICATION DATE: 08/03/2004
Name: BENNETT'S DOCK
SC
NOAA Chart: 11535 Latitude: 33° 26.1' N ( 33.43500)
USGS Quad: WAVERLY MILLS Longitude: 79° 7.6' W ( -79.12670)
T I D A L D A T U M S
Tidal datums at BENNETT'S DOCK based on:
LENGTH OF SERIES: 4 MONTHS
TIME PERIOD: August 1975 - November 1975
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:
MEAN HIGHER HIGH WATER MHHW = 1.352
MEAN HIGH WATER MHW = 1.240
MEAN SEA LEVEL MSL = 0.676
MEAN TIDE LEVEL MTL = 0.656
North American Vertical Datum NAVD88 = 0.639
MEAN LOW WATER MLW = 0.071
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
BD NO 1 1975 2.519 1.279
BD NO 2 1975 3.624 2.384
1989 G 1982 2.933 1.693
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
Station ID: 8661989 PUBLICATION DATE: 08/03/2004
Name: BENNETT'S DOCK
SC
NOAA Chart: 11535 Latitude: 33° 26.1' N ( 33.43500)
USGS Quad: WAVERLY MILLS Longitude: 79° 7.6' W ( -79.12670)
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.