U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
PUBLICATION DATE: 08/01/1984
Station ID: 8661493 SUPERCEDED DATE: 04/21/2003
Name: WACHESAW LANDING, WACCAMAW RIVER
SOUTH CAROLINA
NOAA Chart: 11535 Latitude: 33° 33.6' N
USGS Quad: BROOKGREEN Longitude: 79° 5.1' W
To reach the tidal bench marks from the intersection of U.S. Highway 17 By-Pass
and S-22-62 in Murrells Inlet, proceed west on S-22-62 for 2.5 miles (4.0 km) to
Wacca Wache Marina located on the east bank of the Waccamaw River. The bench
marks are located in the vicinity of the parking area at Wachesaw Landing and
west of the Wachesaw main house. The tide gage and staff were located on the
north side of the wood dock at Wachesaw Marina.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 1493 A 1981
MONUMENTATION: Survey Disk VM#: 3776
AGENCY: PID#: DD1476
SETTING CLASSIFICATION: Galvanized Steel Rod
The bench mark is located 47.0 feet (14.3 m) NNE of the center of the concrete
boat ramp, 42.6 feet (13.0 m) SE of the SE corner of marina store, 12.6 feet
(3.8 m) east of guy-wire anchor, 5.6 feet (1.7 m) SW of the SW corner of the
marina basin, and 2.7 feet (0.8 m) west of power pole #KD3A. The bench mark is
at ground level, crimped to a galvanized steel rod driven 29 feet (9 m) to
refusal, encased in a 4-inch PVC pipe and concrete.
BENCH MARK STAMPING: 1493 B 1981
MONUMENTATION: Survey Disk VM#: 3777
AGENCY: PID#: DD1475
SETTING CLASSIFICATION: Galvanized Steel Rod
The bench mark is 230 feet (70 m) ESE of Bench Mark 1493 A 1981, 52.2 feet (15.9
m) SE of twin cypress tree, 22.5 feet (6.9 m) SW of 1.5 feet (0.5 m) diameter
cypress tree, 8.5 feet (2.6 m) NNE of the north edge of the paved road
(S-22-62), and 3.6 feet (1.1 m) SSE of power pole #KD2A. The bench mark is 0.2
foot (0.1 m) below ground level, crimped to a galvanized steel rod driven 7 feet
(2 m) to refusal, encased in a 4-inch PVC pipe and concrete.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
PUBLICATION DATE: 08/01/1984
Station ID: 8661493 SUPERCEDED DATE: 04/21/2003
Name: WACHESAW LANDING, WACCAMAW RIVER
SOUTH CAROLINA
NOAA Chart: 11535 Latitude: 33° 33.6' N
USGS Quad: BROOKGREEN Longitude: 79° 5.1' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1493 C 1981
MONUMENTATION: Survey Disk VM#: 3778
AGENCY: PID#: DD1474
SETTING CLASSIFICATION: Galvanized Steel Rod
The bench mark is located 214 feet (65 m) east of Bench Mark 1493 B 1981, 15.6
feet (4.8 m) NE of a triangular Dead End sign, 13.0 feet (4.0 m) north of the
north edge of the paved road (S-22-62), 10.0 feet (3.0 m) south of guy-wire
anchor, and 2.9 feet (0.9 m) east of power pole #KD1A. The bench mark is 0.2
feet (0.1 m) below ground level, crimped, to a galvanized steel rod driven 48
feet (15 m) to refusal, encased in a 4-inch PVC pipe and concrete.
BENCH MARK STAMPING: 1493 D 1981
MONUMENTATION: Survey Disk VM#: 3779
AGENCY: PID#: DD1473
SETTING CLASSIFICATION: Galvanized Steel Rod
The bench mark is 243 feet (74 m) SE of Bench Mark 1493 C 1981, 19.8 feet (6.0
m) SSW of centerline of paved road (S-22-62) leading to the marina, 13.8 feet
(4.2 m) WNW of center of drive to Wachesaw Farm and 7.0 feet (2.1 m) NW of the
easternmost gate post on the west side of drive to Wachesaw Farm. The bench
mark is at ground level, crimped to a galvanized steel rod driven (15 m) to
refusal, encased in a 4-inch PVC pipe and concrete.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
PUBLICATION DATE: 08/01/1984
Station ID: 8661493 SUPERCEDED DATE: 04/21/2003
Name: WACHESAW LANDING, WACCAMAW RIVER
SOUTH CAROLINA
NOAA Chart: 11535 Latitude: 33° 33.6' N
USGS Quad: BROOKGREEN Longitude: 79° 5.1' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 4 1934
MONUMENTATION: Survey Disk VM#: 3780
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Monument
The bench mark is located on the Wachewaw Farm grounds 95.3 feet (29 m) SSW of
the SE corner of the main house, 90.1 feet (27.5 m) NNW of the NW corner of the
main section of a log guest house, 81.3 feet (24.8 m) WSW of a 2.0 feet (0.6 m)
diameter cedar tree, 70.5 feet (21.5 m) WNW of a 1.0 foot (0.3 m) magnolia tree,
and 24.0 feet (7.3 m) SE of the center of a 2.5 feet (0.8 m) diameter oak tree.
BENCH MARK STAMPING: WACHESAW 1934 1962
MONUMENTATION: Survey Disk VM#: 3781
AGENCY: PID#: DD2787
SETTING CLASSIFICATION: Concrete Monument
The bench mark is located on the front lawn (river side) of the main house of
Wachesaw Farm, 170.3 feet (51.9 m) NNW of Bench Mark No. 4 1934, 124.3 feet
(37.9 m) SW of the NW garage portion of main house, 82.4 feet (25.1 m) NW of the
SE corner of the sunroom of house, 53.4 (16.3 m) west of the center of three
large picture windows on the west side of the house, and 41.0 feet (12.5 m) east
of the bluff edge.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
PUBLICATION DATE: 08/01/1984
Station ID: 8661493 SUPERCEDED DATE: 04/21/2003
Name: WACHESAW LANDING, WACCAMAW RIVER
SOUTH CAROLINA
NOAA Chart: 11535 Latitude: 33° 33.6' N
USGS Quad: BROOKGREEN Longitude: 79° 5.1' W
T I D A L D A T U M S
Tidal datums at WACHESAW LANDING, WACCAMAW RIVER based on:
LENGTH OF SERIES: 1 YEAR
TIME PERIOD: OCTOBER 1981-SEPTEMBER 1982
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8661070 SPRINGMAID PIER
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (02/27/1982) = 4.15
MEAN HIGHER HIGH WATER MHHW = 3.05
MEAN HIGH WATER MHW = 2.90
MEAN TIDE LEVEL MTL = 1.53
MEAN LOW WATER MLW = 0.16
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (04/07/1982) = -1.61
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
1493 A 1981 4.12 1.22
1493 B 1981 4.46 1.56
1493 C 1981 12.09 9.19
1493 D 1981 16.30 13.40
NO 4 1934 20.29 17.39
WACHESAW 1934 1962 19.86 16.96
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
PUBLICATION DATE: 08/01/1984
Station ID: 8661493 SUPERCEDED DATE: 04/21/2003
Name: WACHESAW LANDING, WACCAMAW RIVER
SOUTH CAROLINA
NOAA Chart: 11535 Latitude: 33° 33.6' N
USGS Quad: BROOKGREEN Longitude: 79° 5.1' 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.