U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
PUBLICATION DATE: 09/18/1985
Station ID: 8661559 SUPERCEDED DATE: 04/21/2003
Name: SMITHS DOCK M-5, MURRELLS INLET
SOUTH CAROLINA
NOAA Chart: 11535 Latitude: 33° 32.7' N
USGS Quad: BROOKGREEN Longitude: 79° 2.7' W
To reach the tidal bench marks from South Myrtle Beach proceed 13.8 miles (22.2
km) SW on US Highway 17 (business) to Vauxhall Avenue, proceed 0.11 mile (0.18
km) SE on Vauxhall Avenue to its end, then south on a sandy marsh front road to
Smiths Dock. The bench marks are located along US Highway 17 (business) and
along Vauxhall Avenue (State Route S-22-63). The tide gage and staff were
located on a dock behind Dr. Smiths House.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: SD NO 1 1975
MONUMENTATION: Survey Disk VM#: 3793
AGENCY: PID#: DD1478
SETTING CLASSIFICATION: Copper-clad Steel Rod
The bench mark is 51.8 feet (15.8 m) east of the east corner of the porch of a
brick house, 25.5 feet (7.8 m) south of the intersection of Vauxhall Avenue and
a sandy marsh front road, 20.3 feet (6.2 m) NW of a 1-foot (0.3 m) embankment in
the marsh, and 13.0 feet (4.0 m) SE of the centerline of the marsh front road.
The bench mark is 0.1 foot (0.03 m) below ground level, crimped to a copper-clad
steel rod driven 48 feet (15 m) to refusal, encased in PVC pipe and a concrete
kickblock.
BENCH MARK STAMPING: SD NO 2 1975
MONUMENTATION: Survey Disk VM#: 3794
AGENCY: PID#: DD1477
SETTING CLASSIFICATION: Copper-clad Steel Rod
The bench mark is 375 feet (114 m) NW of Bench Mark SD NO 1 1975, 195 feet (59
m) east of US Highway 17 (business) along Vauxhall Avenue, 100.5 feet (30.6 m)
east of the east corner of Murrells Inlet Post Office, 14.0 feet (4.3 m) ENE of
the centerline of Vauxhall Road, and 3.7 feet (1.1 m) WSW of utility pole #A-H
1/2 A. The bench mark is 0.2 foot (0.1 m) below ground level, crimped to a
copper-clad steel rod driven 45 feet (14 m) to refusal, encased in PVC pipe and
a concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
PUBLICATION DATE: 09/18/1985
Station ID: 8661559 SUPERCEDED DATE: 04/21/2003
Name: SMITHS DOCK M-5, MURRELLS INLET
SOUTH CAROLINA
NOAA Chart: 11535 Latitude: 33° 32.7' N
USGS Quad: BROOKGREEN Longitude: 79° 2.7' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: SD NO 3 1975
MONUMENTATION: Survey Disk VM#: 3795
AGENCY: PID#: DD4661
SETTING CLASSIFICATION: Concrete Monument
The bench mark is set in a concrete monument at the north corner of Murrells
Inlet Post Office, 58.7 feet (17.9 m) south of utility pole #A17, 55.0 feet
(16.8 m) SE of the centerline of US Highway 17 (business), 33.5 feet (10.2 m) SW
of the centerline of Vauxhall Avenue, and 0.9 foot (0.3 m) NE of the NE wall of
the post office. The bench mark is level with the ground.
BENCH MARK STAMPING: SD NO 4 1975
MONUMENTATION: Survey Disk VM#: 3796
AGENCY: PID#: DD1470
SETTING CLASSIFICATION: Copper-clad Steel Rod
The bench mark is 120 feet (37 m) NNW of Bench Mark SD NO 3 1975, 51.7 feet
(15.8 m) NW of the centerline of US Highway 17 (business), 23 feet (7 m) NE of
Vauxhall Avenue, 6.6 feet (2.0 m) south of a large pine tree, and 3.5 feet (1.1
m) SE of utility pole #U1A. The bench mark is level with the ground, crimped to
a copper-clad steel rod driven 46 feet (14 m) to refusal, encased in PVC pipe
and a concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
PUBLICATION DATE: 09/18/1985
Station ID: 8661559 SUPERCEDED DATE: 04/21/2003
Name: SMITHS DOCK M-5, MURRELLS INLET
SOUTH CAROLINA
NOAA Chart: 11535 Latitude: 33° 32.7' N
USGS Quad: BROOKGREEN Longitude: 79° 2.7' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1559 F 1982
MONUMENTATION: Survey Disk VM#: 3797
AGENCY: PID#: DD4662
SETTING CLASSIFICATION: Stainless Steel Rod
The bench mark is 0.1 mile (0.2 km) NE of Murrells Inlet Post Office, 38.8 feet
(11.8 m) SE of the centerline of US Highway 17 (business), 23.3 feet (7.1 m)
east of the center of a manhole cover, 18.0 feet (5.5 m) ENE of the centerline
of State Road S-22-539, 8.6 feet (2.6 m) SW of utility pole #12763, 3.0 feet
(0.9 m) south of telephone junction box #2-20, and 0.9 foot (0.3 m) NW of a
witness post and sign. The bench mark is crimped to a stainless steel rod
driven 42 feet (13 m) to refusal, encased in PVC pipe and a concrete kickblock.
BENCH MARK STAMPING: 1559 G 1982
MONUMENTATION: Survey Disk VM#: 3798
AGENCY: PID#: DD4663
SETTING CLASSIFICATION: Stainless Steel Rod
The bench mark is 0.25 mile (0.40 km) NE of Murrells Inlet Post Office, 84.5
feet (25.8 m) NW of utility pole #13657, 49.6 feet (15.1 m) north of the NW
corner of a two-story tan dwelling, 32.0 feet (9.8 m) SE of the centerline of US
Highway 17 (business), and 7.1 feet (2.2 m) NE of utility pole #48 A. The bench
mark is crimped to a stainless steel rod driven 38 feet (12 m) to refusal,
encased in PVC pipe and a concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
PUBLICATION DATE: 09/18/1985
Station ID: 8661559 SUPERCEDED DATE: 04/21/2003
Name: SMITHS DOCK M-5, MURRELLS INLET
SOUTH CAROLINA
NOAA Chart: 11535 Latitude: 33° 32.7' N
USGS Quad: BROOKGREEN Longitude: 79° 2.7' W
T I D A L D A T U M S
Tidal datums at SMITHS DOCK M-5, MURRELLS INLET based on:
LENGTH OF SERIES: 12 MONTHS
TIME PERIOD: February 1975 - January 1976
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 (06/10/1975) = 7.08
MEAN HIGHER HIGH WATER MHHW = 4.90
MEAN HIGH WATER MHW = 4.52
MEAN TIDE LEVEL MTL = 2.36
MEAN LOW WATER MLW = 0.19
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (01/01/1976) = -1.18
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
SD NO 1 1975 8.99 4.47
SD NO 2 1975 10.50 5.98
SD NO 3 1975 12.61 8.09
SD NO 4 1975 11.24 6.72
1559 F 1982 9.29 4.77
1559 G 1982 7.77 3.25
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
PUBLICATION DATE: 09/18/1985
Station ID: 8661559 SUPERCEDED DATE: 04/21/2003
Name: SMITHS DOCK M-5, MURRELLS INLET
SOUTH CAROLINA
NOAA Chart: 11535 Latitude: 33° 32.7' N
USGS Quad: BROOKGREEN Longitude: 79° 2.7' 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.