U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
PUBLICATION DATE: 01/29/1988
Station ID: 8670073 SUPERCEDED DATE: 04/21/2003
Name: SEABOARD RR BRIDGE, SAVANNAH RIVER
GEORGIA
NOAA Chart: Latitude: 32° 13.9' N
USGS Quad: PORT WENTWORTH Longitude: 81° 8.7' W
To reach the tidal bench marks by boat from the public boat landing at Port
Wentworth, proceed north on the Savannah River for approximately 5 miles (8 km).
The bench marks are located on the Seaboard Coast Line Railroad Bridge and on
the Georgia side of the Savannah River. The tide gage and staff were located on
the bridge attendants house platform.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 0073 D 1980
MONUMENTATION: Survey Disk VM#: 4713
AGENCY: PID:
SETTING CLASSIFICATION: Stainless Steel Rod
The bench mark is 26.2 feet (8.0 m) NW of the centerline of the railroad trestle
at support #147, 12.7 feet (3.9 m) ESE of the last wood pole supporting a
catwalk, and 9.5 feet (2.9 m) below the catwalk leading to a junction box on a
utility pole. The bench mark is 0.2 foot (0.1 m) below ground level, crimped to
a stainless steel rod driven 42 feet (13 m) to refusal, and encased in a 4-inch
orange PVC pipe and concrete kickblock.
BENCH MARK STAMPING: END 1934
MONUMENTATION: Survey Disk VM#: 4710
AGENCY: PID#: CK0441
SETTING CLASSIFICATION: Concrete Monument
The bench mark is set in the top of a concrete monument, 93.5 feet (28.5 m) WNW
of Bench Mark END NO 2 1934, 78.6 feet (24.0 m) west of Bench Mark 0073 D 1980,
1.1 feet (0.3 m) east of a pole extending 4 feet (1.2 m) above the ground, and
level with the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
PUBLICATION DATE: 01/29/1988
Station ID: 8670073 SUPERCEDED DATE: 04/21/2003
Name: SEABOARD RR BRIDGE, SAVANNAH RIVER
GEORGIA
NOAA Chart: Latitude: 32° 13.9' N
USGS Quad: PORT WENTWORTH Longitude: 81° 8.7' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: END NO 1 1934
MONUMENTATION: Survey Disk VM#: 4711
AGENCY: PID#: CK0448
SETTING CLASSIFICATION: Concrete Pillar
The bench mark is set flush in a concrete pillar of the railroad trestle at
support #150, 147.2 feet (44.9 m) SW of Bench Mark 0073 D 1980, 45.0 feet (13.7
m) south of a utility pole, 8.3 feet (2.5 m) NNW of the centerline of the
railroad track, 0.3 foot (0.1 m) south of the NW corner of the concrete pillar,
and 10.0 feet (3.0 m) below the railroad track.
BENCH MARK STAMPING: END NO 2 1934
MONUMENTATION: Survey Disk VM#: 4712
AGENCY: PID#: CK0442
SETTING CLASSIFICATION: Concrete Pillar
The bench mark is set flush in a concrete pillar of the railroad trestle at
support #146, 42.6 feet (13.0 m) NE of Bench Mark 0073 D 1980, 36.2 feet (11.0
m) NE of the NE corner of a shed, 6.2 feet (1.9 m) NNE of the centerline of the
railroad track, 1.1 feet (0.3 m) ESE of the NW side of the pillar, and 6.2 feet
(1.9 m) below the railroad track.
BENCH MARK STAMPING: 0073 E 1980
MONUMENTATION: Survey Disk VM#: 4714
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Pillar
The bench mark is set flush in a concrete pillar of the railroad trestle at the
pedestal end of the bascule-type railroad bridge, 534.0 feet (162.8 m) NE of
Bench Mark END NO 2 1934, 14.3 feet (4.4 m) SE of the centerline of the railroad
track, 1.8 feet (0.5 m) west of the SE face of the concrete pillar, and 5.8 feet
(1.8 m) below the railroad track.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
PUBLICATION DATE: 01/29/1988
Station ID: 8670073 SUPERCEDED DATE: 04/21/2003
Name: SEABOARD RR BRIDGE, SAVANNAH RIVER
GEORGIA
NOAA Chart: Latitude: 32° 13.9' N
USGS Quad: PORT WENTWORTH Longitude: 81° 8.7' W
T I D A L D A T U M S
Tidal datums at SEABOARD RR BRIDGE, SAVANNAH RIVER based on:
LENGTH OF SERIES: 5 MONTHS
TIME PERIOD: SEPTEMBER 1980 - JANUARY 1981
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8670870 FORT PULASKI
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (02/28/1983) = 8.76
MEAN HIGHER HIGH WATER MHHW = 7.19
MEAN HIGH WATER MHW = 6.92
MEAN TIDE LEVEL MTL = 3.52
* NATIONAL GEODETIC VERTICAL DATUM NGVD29 = 2.35
MEAN LOW WATER MLW = 0.11
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (02/02/1981) = -0.25
* NGVD reference based on elevations published in Quad 320812, 1964, and NOS
leveling of 1983.
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
0073 D 1980 7.61 0.69
END 1934 7.17 0.25
END NO 1 1934 8.48 1.56
END NO 2 1934 14.35 7.43
0073 E 1980 14.83 7.91
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
PUBLICATION DATE: 01/29/1988
Station ID: 8670073 SUPERCEDED DATE: 04/21/2003
Name: SEABOARD RR BRIDGE, SAVANNAH RIVER
GEORGIA
NOAA Chart: Latitude: 32° 13.9' N
USGS Quad: PORT WENTWORTH Longitude: 81° 8.7' 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.