U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
PUBLICATION DATE: 04/19/1984
Station ID: 8664131 SUPERCEDED DATE: 04/21/2003
Name: BACK RIVER RESERVOIR, BACK RIVER
SOUTH CAROLINA
NOAA Chart: 11527 Latitude: 32° 59.0' N
USGS Quad: NORTH CHARLESTON Longitude: 79° 56.2' W
To reach the tidal bench marks from U.S. Highway 52 in Goose Creek, S.C.,
proceed east 6.8 miles (10.9 km) on East Red Bank Road through U.S. Naval
Reservation and Weapons Station to Bushy Park Road (S.C. Secondary Route #503),
proceed NNE 0.5 mile (0.8 km) on Bushy Park Road to public landing at Back River
Reservoir. Travel by a boat from western side of landing, proceed in northerly
direction on Back River for approximately 2 miles (3 km) and the bench marks are
located on the eastern shore at the Back River Reservoir and the side of Bushy
Park Road. The gage and staff were located on a constructed platform.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: WIND 1928
MONUMENTATION: Survey Disk VM#: 4031
AGENCY: PID#: CJ0563
SETTING CLASSIFICATION: Concrete Monument
The bench mark is 0.4 foot (0.1 m) above ground level set flush in a concrete
monument, located on eastern shore of Back River, 25.0 feet (7.6 m) NNW of Bench
Mark WIND NO 3 1928, 24.0 feet (7.3 m) west of 0.7 foot (0.2 m) diameter oak
tree, 8.0 feet (2.4 m) ESE of edge of river bank of Back River, and 2.9 feet
(0.9 m) WNW of witness post with sign.
BENCH MARK STAMPING: WIND NO 3 1928
MONUMENTATION: Survey Disk VM#: 4032
AGENCY: PID#: CJ0561
SETTING CLASSIFICATION: Concrete Monument
The bench mark is 0.5 foot (0.2 m) above ground level, set flush in a concrete
monument, and is 16.4 feet (5.0 m) SW of 1.5 feet (0.5 m) diameter pine tree 5.3
feet (1.6 m) south of 0.5 foot (0.2 m) diameter twin oak, and 1.8 feet (0.5 m)
ENE of metal witness post with sign.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
PUBLICATION DATE: 04/19/1984
Station ID: 8664131 SUPERCEDED DATE: 04/21/2003
Name: BACK RIVER RESERVOIR, BACK RIVER
SOUTH CAROLINA
NOAA Chart: 11527 Latitude: 32° 59.0' N
USGS Quad: NORTH CHARLESTON Longitude: 79° 56.2' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4131 D 1981
MONUMENTATION: Survey Disk VM#: 4033
AGENCY: PID#: CJ0560
SETTING CLASSIFICATION: Stainless Steel Rod
The bench mark is 34.8 feet (10.6 m) SE of river bank of Back River, 28.0 feet
(8.5 m) ESE of 2.0 feet (0.6 m) diameter oak tree, 17.8 feet (5.4 m) NNE of 1.2
feet (0.4 m) diameter oak tree, 10.8 feet (3.3 m) south of 0.8 foot (0.2 m)
diameter oak tree, 4.2 feet (1.3 m) NNE of metal witness post with sign, and 4.2
feet (1.3 m) NNE of metal witness post with sign, and 2.6 feet (0.8 m) NE of
second metal witness post with sign. The bench mark is 0.2 foot (0.1 m) below
ground level crimped to a stainless steel rod driven 33 feet (10 m) to refusal
and encased in 5 inch PVC pipe and concrete kickblock.
BENCH MARK STAMPING: 4131 F 1981
MONUMENTATION: Survey Disk VM#: 4034
AGENCY: PID#: CJ0558
SETTING CLASSIFICATION: Stainless Steel Rod
The bench mark is 2.6 miles (4.2 km) north of intersection of Red Bank Road (SC
Secondary Road #29) and Bushey Park Road (SC Secondary Road #503), located below
the western edge of Bushy Park Road near a telephone pole, approximately 300
feet (91 m) ESE of tree line, 78.0 feet (23.8 m) NW of the centerline of Bushy
Park Road, 6.8 feet (2.1 m) ESE of telephone pole #30 with witness sign, and 4.8
feet (1.5 m) NW of metal witness post with sign. The bench mark is 0.1 foot
(0.03 m) below ground level, crimped to a stainless steel rod driven 31 feet (9
m) to refusal and encased in 5 inch PVC pipe and concrete.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
PUBLICATION DATE: 04/19/1984
Station ID: 8664131 SUPERCEDED DATE: 04/21/2003
Name: BACK RIVER RESERVOIR, BACK RIVER
SOUTH CAROLINA
NOAA Chart: 11527 Latitude: 32° 59.0' N
USGS Quad: NORTH CHARLESTON Longitude: 79° 56.2' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4131 G 1982
MONUMENTATION: Survey Disk VM#: 4035
AGENCY: PID#: CJ0559
SETTING CLASSIFICATION: Stainless Steel Rod
The bench mark is located at the junction of the dense tall tree line and a
field of smaller scrub pine trees and brush, NNW of power pole #30, west of a
two power pole assembly and SW of a single power pole #29, 21.2 feet (6.5 m) SE
of a twin trunked oak tree, and 6.5 feet (2.0 m) SSW of metal witness post and
sign. THe bench mark is 0.2 foot (0.1 m) above ground level, crimped to a
stainless steel rod driven 28 feet (9 m) to refusal and encased in 5 inch PVC
pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
PUBLICATION DATE: 04/19/1984
Station ID: 8664131 SUPERCEDED DATE: 04/21/2003
Name: BACK RIVER RESERVOIR, BACK RIVER
SOUTH CAROLINA
NOAA Chart: 11527 Latitude: 32° 59.0' N
USGS Quad: NORTH CHARLESTON Longitude: 79° 56.2' W
T I D A L D A T U M S
Tidal datums at BACK RIVER RESERVOIR, BACK RIVER based on:
LENGTH OF SERIES: 12 MONTHS
TIME PERIOD: JULY 1981-JUNE 1982
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8665530 CHARLESTON, SC
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (06/19/1982) = 2.80
MEAN HIGHER HIGH WATER MHHW = 1.02
MEAN HIGH WATER MHW = 0.93
MEAN TIDE LEVEL MTL = 0.54
MEAN LOW WATER MLW = 0.15
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (08/01/1982) = -1.65
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
WIND 1928 2.31 1.38
WIND NO 3 1928 2.83 1.90
4131 D 1981 6.78 5.85
4131 F 1981 11.09 10.16
4131 G 1982 9.48 8.55
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
PUBLICATION DATE: 04/19/1984
Station ID: 8664131 SUPERCEDED DATE: 04/21/2003
Name: BACK RIVER RESERVOIR, BACK RIVER
SOUTH CAROLINA
NOAA Chart: 11527 Latitude: 32° 59.0' N
USGS Quad: NORTH CHARLESTON Longitude: 79° 56.2' 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.