U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
PUBLICATION DATE: 03/29/1984
Station ID: 8666217 SUPERCEDED DATE: 04/21/2003
Name: YONGES ISLAND, WADMALAW RIVER
SOUTH CAROLINA
NOAA Chart: 11522 Latitude: 32° 41.7' N
USGS Quad: WADMALAW ISLAND Longitude: 80° 13.4' W
To reach the tidal bench marks from the intersection of U.S. Highway 17 and S.C.
162, proceed south on S.C. 162 7.1 miles (11.4 m) to S.C. 165 in Hollywood S.C.,
south onto S.C. 165 3.3 miles (5.3 km) to Meggett, South Carolina, left at sign
Simmons Bluff 0.4 mile (0.6 km) to Pederson residence. The bench marks are
located west of the Pederson residence and in the vicinity of the Younges Island
Post Office. The gage and staff were located on a private dock behind the
residence.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 6217 F 1977
MONUMENTATION: Survey Disk VM#: 4288
AGENCY: PID#: CK2458
SETTING CLASSIFICATION: Copper-Clad Steel Rod
The bench mark is located at the SW corner of the garage of Pederson residence,
89.0 feet (27.1 m) NE of power pole No. 144010, 47.0 feet (14.3 m) east of the Y
in the dirt driveway, 41.2 feet (12.6 m) SSW of the centerline of brick wall
leading to front door of residence, 15.0 feet (4.6 m) west of the electric meter
box on side of house, and 3.9 feet (1.2 m) WSW of the SW corner of the garage.
The bench Mark is crimped to the top of a copper-clad steel rod driven 32 feet
(10 m) to refusal, encased in 4-inch PVC pipe and concrete kickblock.
BENCH MARK STAMPING: NO 1
MONUMENTATION: Survey Disk VM#: 4283
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is set flush in the top of remains of an old water tower, south
of the Younges Island Post Office, 68.9 feet (21.0 m) NNE of power pole No.
54185, 39.0 feet (11.9 m) east of the centerline of a dirt driveway, 1.5 feet
(0.5 m) NNW of a cinder block wall, and 1.0 foot (0.3 m) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
PUBLICATION DATE: 03/29/1984
Station ID: 8666217 SUPERCEDED DATE: 04/21/2003
Name: YONGES ISLAND, WADMALAW RIVER
SOUTH CAROLINA
NOAA Chart: 11522 Latitude: 32° 41.7' N
USGS Quad: WADMALAW ISLAND Longitude: 80° 13.4' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 2
MONUMENTATION: Survey Disk VM#: 4284
AGENCY: PID:
SETTING CLASSIFICATION: Set flush In Window Sill
The bench mark is set flush in the left side window sill of Yonges Island Post
Office, 16.4 feet (5.0 m) NW of flag pole, 10.5 feet (3.2 m) east of the west
corner of the post office, and 8.0 feet (2.4 m) west of the centerline of the
front door of the post office.
BENCH MARK STAMPING: NO 4 1974
MONUMENTATION: Survey Disk VM#: 4285
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Monument
The bench mark is set flush in a concrete post 143.0 feet (43.6 m) south of
Yonges Island Post Office, 53.5 feet (16.3 m) east of the centerline of a
private road, 25.0 feet (7.6 m) south of the centerline of S.C. Highway 165,
14.2 feet (4.3 m) east of power pole #238758, 3.7 feet (1.1 m) north of a
concrete block wall, and projecting 0.1 foot (0.1 m) above ground level.
BENCH MARK STAMPING: NO 5 1974
MONUMENTATION: Survey Disk VM#: 4286
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Monument
The bench mark is set flush in a concrete post SW of the Yonges Island Post
Office 69.4 feet(21.2 m) west of power pole No. 238758, 29.0 feet (8.8 m) SW of
the centerline of a dirt driveway, 21.6 feet (6.6 m) south of the centerline of
S.C. Highway 165, 4.9 feet (1.5 m) north of a 4.0 feet (1.2 m) tall chainlink
fence and projecting 0.1 foot (0.1 m) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
PUBLICATION DATE: 03/29/1984
Station ID: 8666217 SUPERCEDED DATE: 04/21/2003
Name: YONGES ISLAND, WADMALAW RIVER
SOUTH CAROLINA
NOAA Chart: 11522 Latitude: 32° 41.7' N
USGS Quad: WADMALAW ISLAND Longitude: 80° 13.4' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 6 1974
MONUMENTATION: Survey Disk VM#: 4287
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Monument
The bench mark is set flush in a concrete post, 183.0 feet (55.8 m) SW of Yonges
Island Post Office, 119.7 feet (36.4 m) NW of Bench Mark NO 5 1974, 21.7 feet
(6.6 m) north of the centerline of S.C. Highway 165, 15.8 feet (4.8 m) NE of a
speed limit sign 30 mph, 3.0 feet (0.9 m) east of a unumbered power pole, and
projecting 0.1 foot (0.1 m) above ground level.
BENCH MARK STAMPING: 6217 G 1977
MONUMENTATION: Survey Disk VM#: 4289
AGENCY: PID#: CK2454
SETTING CLASSIFICATION: Copper-Clad Steel Rod
The bench mark is located near the bend in the paved road by power pole No.
77849, 42.0 feet (12.8 m) SW of brick driveway marker, 16.2 feet (4.9 m) SE of
power pole No. 77849, 14.0 feet (4.3 m) west of centerline of paved road, and
3.0 feet (0.9 m) west of the west side of paved road. The bench mark is crimped
to the top of a copper-clad steel rod driven 32 feet (10 m) to refusal, encased
in 4-inch PVC and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
PUBLICATION DATE: 03/29/1984
Station ID: 8666217 SUPERCEDED DATE: 04/21/2003
Name: YONGES ISLAND, WADMALAW RIVER
SOUTH CAROLINA
NOAA Chart: 11522 Latitude: 32° 41.7' N
USGS Quad: WADMALAW ISLAND Longitude: 80° 13.4' W
T I D A L D A T U M S
Tidal datums at YONGES ISLAND, WADMALAW RIVER based on:
LENGTH OF SERIES: 1 YEAR
TIME PERIOD: MAY 1977-APRIL 1978
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8665530 CHARLESTON
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (06/01/1977) = 9.04
MEAN HIGHER HIGH WATER MHHW = 7.12
MEAN HIGH WATER MHW = 6.78
MEAN TIDE LEVEL MTL = 3.50
MEAN LOW WATER MLW = 0.22
LOWEST OBSERVED WATER LEVEL (01/09/1978) = -2.82
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
6217 F 1977 19.49 12.71
NO 1 13.35 6.57
NO 2 17.80 11.20
NO 4 1974 13.05 6.27
NO 5 1974 14.88 8.10
NO 6 1974 18.22 11.44
6217 G 1977 17.02 10.24
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
PUBLICATION DATE: 03/29/1984
Station ID: 8666217 SUPERCEDED DATE: 04/21/2003
Name: YONGES ISLAND, WADMALAW RIVER
SOUTH CAROLINA
NOAA Chart: 11522 Latitude: 32° 41.7' N
USGS Quad: WADMALAW ISLAND Longitude: 80° 13.4' 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 (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 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.