U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
PUBLICATION DATE: 04/03/1986
Station ID: 8668301 SUPERCEDED DATE: 04/21/2003
Name: CHECHESSEE BLUFF, CHECHESSEE RIVER
SOUTH CAROLINA
NOAA Chart: 11513 Latitude: 32° 22.4' N
USGS Quad: SPRING ISLAND Longitude: 80° 50.2' W
To reach the tidal bench marks from the Post Office in Burton proceed 0.4 mile
(0.6 km) SW on State Highway 280 to State Highway 281, then 4.1 miles (6.6 km)
SW and SE on State Highwy 281 to State Highway 170, then 4.5 miles (7.2 km) SW
on State Highway 170 to the west end of the bridge over the Chechessee River.
The bench marks are located along State Highway 170, and south of the highway on
the east side of the river. The tide gage and staff were located 200 feet (61.0
m) east of the west end of the G.G. Dowling Bridge at the west end of a wooden
fishing platform on the north side of the bridge.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: C 104 1962
MONUMENTATION: Survey Disk VM#: 3818
AGENCY: PID#: CK0797
SETTING CLASSIFICATION: Bridge Abutment
The bench mark is in the south abutment of the west end of the bridge, 33.0 feet
(10.1 m) north of utility pole #266658, 32.5 feet (9.9 m) WSW of Bench Mark 8301
H 1978, 16.7 feet (5.1 m) west of an underground telephone marker, 16.0 feet
(4.9 m) south of the centerline of the highway, and 3.0 feet (0.9 m) east of the
bridge dedication plaque.
BENCH MARK STAMPING: NO 1
MONUMENTATION: Survey Disk VM#: 3811
AGENCY: PID#: CK0799
SETTING CLASSIFICATION: Concrete Monument
The bench mark is NE of some pier pilings for an abandoned dock, 534.0 feet
(162.8 m) SE of the SE corner of the bridge, 365.0 feet (111.3 m) south of the
centerline of the highway, 238.9 feet (72.8 m) south of Bench Mark NO 4 1973,
68.4 feet (20.8 m) north of the center of the landward end of the dike leading
to the old pier, 13.0 feet (4.0 m) south of a small cedar tree, and 2.3 feet
(7.0 m) ENE of a metal witness post. The bench mark is set in sewer tile filled
with concrete, projecting 0.2 foot (0.1 m) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
PUBLICATION DATE: 04/03/1986
Station ID: 8668301 SUPERCEDED DATE: 04/21/2003
Name: CHECHESSEE BLUFF, CHECHESSEE RIVER
SOUTH CAROLINA
NOAA Chart: 11513 Latitude: 32° 22.4' N
USGS Quad: SPRING ISLAND Longitude: 80° 50.2' 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#: 3812
AGENCY: PID#: CK0800
SETTING CLASSIFICATION: Concrete Monument
The bench mark is located 203.2 feet (61.9 m) SE of Bench Mark NO 1, 164 feet
(50 m) SSE of the inshore end of the abandoned dock, 51.0 feet (15.5 m) WNW of a
lone palmetto tree, 39.2 feet (11.9 m) NNE of the shoreline, and 2.0 feet (0.6
m) NW of a metal witness post. The bench mark is set in sewer tile filled with
concrete, projecting 0.3 foot (0.1 m) above ground level.
BENCH MARK STAMPING: NO 4 1973
MONUMENTATION: Survey Disk VM#: 3814
AGENCY: PID#: CK2155
SETTING CLASSIFICATION: Concrete Monument
The bench mark is 394 feet (120 m) east along the highway from the east end of
the bridge, 100.5 feet (31 m) south of the centerline of the highway, 50.7 feet
(15.5 m) west of the centerline of a dirt road, 3.0 feet (0.9 m) NW of the
northernmost of two sign posts, and 0.1 foot (0.03 m) below ground level.
BENCH MARK STAMPING: NO 5 1973
MONUMENTATION: Survey Disk VM#: 3815
AGENCY: PID#: CK2154
SETTING CLASSIFICATION: Concrete Monument
The bench mark is 256.5 feet (78.2 m) SE of the SE corner of the east end of the
bridge, 248 feet (76 m) east along the highway from the east end of the bridge,
144.4 feet (44.0 m) WNW of Bench Mark NO 4 1973, 79.9 feet (24.4 m) south of the
centerline of the highway, 29.5 feet (9.0 m) east of a utility pole, 10.4 feet
(3.2 m) north of the crotch of a double pine tree, 3.0 feet (0.9 m) north of a
metal witness post, and at ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
PUBLICATION DATE: 04/03/1986
Station ID: 8668301 SUPERCEDED DATE: 04/21/2003
Name: CHECHESSEE BLUFF, CHECHESSEE RIVER
SOUTH CAROLINA
NOAA Chart: 11513 Latitude: 32° 22.4' N
USGS Quad: SPRING ISLAND Longitude: 80° 50.2' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 8301 H 1978
MONUMENTATION: Survey Disk VM#: 3816
AGENCY: PID#: CK2152
SETTING CLASSIFICATION: Stainless Steel Rod
The bench mark is west of the river, 35.2 feet (10.7 m) ENE of Bench Mark C 104
1962, 31.2 feet (9.5 m) south of utility pole #266659, 18.9 feet (5.8 m) north
of the centerline of the highway, 9.1 feet (2.8 m) west of the NW corner of the
west end of the bridge, and 2.7 feet (0.8 m) ESE of a steel witness post. The
bench mark is crimped to the top of a stainless steel rod driven 38 feet (12 m)
to refusal, encased in a PVC pipe and concrete kickblock, and 0.2 foot (0.1 m)
below ground level.
BENCH MARK STAMPING: 8301 I 1978
MONUMENTATION: Survey Disk VM#: 3817
AGENCY: PID#: CK2153
SETTING CLASSIFICATION: Stainless Steel Rod
The bench mark is 33.9 feet (10.3 m) north of the centerline of the highway,
18.9 feet (5.8 m) north of the NE corner of the east end of the bridge, 16.5
feet (5.0 m) SE of a twin pine tree, 15.3 feet (4.7 m) south of a brace power
pole, and 2.2 feet (0.7 m) NE of a steel witness post. The bench mark is
crimped to the top of a stainless steel rod driven 42 feet (13 m) to refusal,
encased in a PVC pipe and concrete kickblock, and 0.2 foot (0.1 m) below ground
level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
PUBLICATION DATE: 04/03/1986
Station ID: 8668301 SUPERCEDED DATE: 04/21/2003
Name: CHECHESSEE BLUFF, CHECHESSEE RIVER
SOUTH CAROLINA
NOAA Chart: 11513 Latitude: 32° 22.4' N
USGS Quad: SPRING ISLAND Longitude: 80° 50.2' W
T I D A L D A T U M S
Tidal datums at CHECHESSEE BLUFF, CHECHESSEE RIVER based on:
LENGTH OF SERIES: 8 MONTHS
TIME PERIOD: JUNE 1978-JANUARY 1979
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8667999 BEAUFORT
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (09/04/1979) = 11.83
MEAN HIGHER HIGH WATER MHHW = 8.21
MEAN HIGH WATER MHW = 7.84
* NATIONAL GEODETIC VERTICAL DATUM NGVD29 = 4.06
MEAN TIDE LEVEL MTL = 4.03
MEAN LOW WATER MLW = 0.22
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (01/29/1979) = -2.91
* NGVD reference based on elevations published in Quad 320803, 1964, and NOS
leveling of 1979.
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
C 104 1962 21.81 13.97
NO 1 9.89 2.05
NO 2 9.71 1.87
NO 4 1973 10.54 2.70
NO 5 1973 12.03 4.19
8301 H 1978 21.10 13.26
8301 I 1978 14.57 6.73
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
PUBLICATION DATE: 04/03/1986
Station ID: 8668301 SUPERCEDED DATE: 04/21/2003
Name: CHECHESSEE BLUFF, CHECHESSEE RIVER
SOUTH CAROLINA
NOAA Chart: 11513 Latitude: 32° 22.4' N
USGS Quad: SPRING ISLAND Longitude: 80° 50.2' 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.