U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
PUBLICATION DATE: 06/22/1992
Station ID: 8666359 SUPERCEDED DATE: 04/21/2003
Name: BLUFF PLANTATION, COMBAHEE RIVER
SOUTH CAROLINA
NOAA Chart: Latitude: 32° 41.0' N
USGS Quad: Green Pond Longitude: 80° 44.3' W
To reach the tidal bench marks from the junction of US Highways 17 and 17 A (21
N), proceed on US Highway 17A for 11.4 miles (18.3 km) to County Road S- 15-66,
turn right and go east on County Road S-15-66 for 5.6 miles (9.0 km) to Bluff
Plantation, turn right and go 0.2 mile (0.3 km) to the turn around circle. The
bench marks are along the east driveway on Bluff Plantation. The gauge and
staff were on a small wooden pier on the Combahee River at the mouth of the
canal.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: BP NO 2 1975
MONUMENTATION: Survey Disk VM#: 10587
AGENCY: PID#: CK2948
SETTING CLASSIFICATION: Copper-clad Steel Rod
The primary bench mark is in the vicinity of the turn around circle on Bluff
Plantation, 202.0 feet (61.6 m) WSW of the NW post of the overhang on the horse
stables, 97.8 feet (29.8 m) NNE of the north face of a 4.0 foot (1.2 m) diameter
magnolia tree, 81.0 feet (24.7 m) north of the north face of a 2.0 foot (0.6 m)
diameter cedar tree, 45.5 feet (13.9 m) south of the centerline of the asphalt
road leading from turning circle to the stables and 8.0 feet (2.4 m) west of a
2.0 foot (0.6 m) diameter pine tree. The bench mark is 0.1 foot (0.03 m) below
ground level, crimped to a copper-clad steel rod driven 40 feet (12 m) to
refusal, and encased in a 4 inch PVC pipe and concrete kicblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
PUBLICATION DATE: 06/22/1992
Station ID: 8666359 SUPERCEDED DATE: 04/21/2003
Name: BLUFF PLANTATION, COMBAHEE RIVER
SOUTH CAROLINA
NOAA Chart: Latitude: 32° 41.0' N
USGS Quad: Green Pond Longitude: 80° 44.3' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: BP NO 3 1975
MONUMENTATION: Survey Disk VM#: 10588
AGENCY: PID#: CK2947
SETTING CLASSIFICATION: Copper-Clad Steel Rod
The bench mark is along the east side of the east drive of Bluff Plantation,
480.9 feet (146.6 m) NE of bench mark BP NO 2 1975 152.0 feet (46.3 m) NW of the
white fence around horse pasture, 50.5 feet (15.4 m) south of the south edge of
the drainage ditch, 12.2 feet (3.7 m) north of the 10th live oak tree along east
side of east drive and 12.0 feet (3.7 m) east of the centerline of the east
drive. The bench mark is 0.3 foot (0.1 m) below ground level, crimped to a
copper-clad steel rod driven 32 feet (10 m) to refusal, and encased in 4 inch
PVC pipe and concrete kickblock.
BENCH MARK STAMPING: BP NO 4 1975
MONUMENTATION: Survey Disk VM#: 10589
AGENCY: PID#: CK2946
SETTING CLASSIFICATION: Copper-clad Steel Rod
The bench mark is nera the east edge of a small pond on the west side of the
east drive on Bluff Plantation, 77.7 feet (23.7 m) SW of a 5.0 foot (1.5 m)
diameter live oak tree (4th tree from entrance on east side of drive), 30.0 feet
(9.1 m) west of the centerline of the east drive, and 13.0 feet (4.0 m) east of
the east face of a 3.0 feet (0.9 m) diameter live oak tree on the east side of
pond. The bench mark is 0.2 foot (0.1 m) below ground level, crimped to a
copper-clad steel rod driven 48 feet (15 m) to refusal, and encased in 4- inch
PVC pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
PUBLICATION DATE: 06/22/1992
Station ID: 8666359 SUPERCEDED DATE: 04/21/2003
Name: BLUFF PLANTATION, COMBAHEE RIVER
SOUTH CAROLINA
NOAA Chart: Latitude: 32° 41.0' N
USGS Quad: Green Pond Longitude: 80° 44.3' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 19 FEET DATUM 1917
MONUMENTATION: Pipe Cap VM#: 10590
AGENCY: PID#: CK2945
SETTING CLASSIFICATION: Steel Pipe
The bench mark is on the NW side of the east drive at the entrance to Bluff
Plantation, 59.0 feet (18.0 m) west of the underground phone cable box 13-32-
14, 34.0 feet (10.4 m) south of the centerline of County Road S-15-66, 17.9 feet
(5.5 m) west of the centerline of the east entrance, and 3.4 feet (1.0 m) north
of the north face of the brick wall at the east entrance, and 3.4 feet (1.0 m)
north of the north face of the brick wall at the east entrance. The bench mark
is 1.2 feet (0.4 m) above ground level, bolted to the top of a 3 inch diameter
steel pipe, surrounded by concrete.
BENCH MARK STAMPING: 6359 F 1981
MONUMENTATION: Survey Disk VM#: 10591
AGENCY: PID#: CK2949
SETTING CLASSIFICATION: Concrete Monument
The bench mark is set flush in the top of a concrete monument near Nathaniel
Heywards tomb on the SE side of Bluff Plantation, 87.3 feet (26.6 m) SSW of the
SW corner of the tennis courts, 32.7 feet (10.0 m) east of the east face of a
cedar tree, 19.4 feet (5.9 m) west of the west face of a 1.5 foot (0.5 m)
diameter oak tree, and 1.9 feet (0.6 m) SSW of the NE corner of the brick wall
around Nathaniel Heywards grave site.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
PUBLICATION DATE: 06/22/1992
Station ID: 8666359 SUPERCEDED DATE: 04/21/2003
Name: BLUFF PLANTATION, COMBAHEE RIVER
SOUTH CAROLINA
NOAA Chart: Latitude: 32° 41.0' N
USGS Quad: Green Pond Longitude: 80° 44.3' W
T I D A L D A T U M S
Tidal datums at BLUFF PLANTATION, COMBAHEE RIVER based on:
LENGTH OF SERIES: 58 MONTHS
TIME PERIOD: 1979-1984
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 (03/16/1980) = 5.60
MEAN HIGHER HIGH WATER MHHW = 3.67
MEAN HIGH WATER MHW = 3.52
MEAN TIDE LEVEL MTL = 1.93
* North American Vertical Datum NAVD88 = 1.31
* NATIONAL GEODETIC VERTICAL DATUM NGVD29 = 0.40
MEAN LOW WATER MLW = 0.34
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (02/29/1984) = -3.19
* NGVD reference based on elevations published in Quad 320804, 1992, and NOS
leveling of 1984.
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
BP NO 2 1975 17.95 14.43
BP NO 3 1975 13.78 10.26
BP NO 4 1975 13.91 10.39
19 FEET DATUM 1917 18.94 15.42
6359 F 1981 18.49 14.97
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
PUBLICATION DATE: 06/22/1992
Station ID: 8666359 SUPERCEDED DATE: 04/21/2003
Name: BLUFF PLANTATION, COMBAHEE RIVER
SOUTH CAROLINA
NOAA Chart: Latitude: 32° 41.0' N
USGS Quad: Green Pond Longitude: 80° 44.3' 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.