U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8664531 PUBLICATION DATE: 04/01/2004
Name: BACON BRIDGE, ASHLEY RIVER
SC
NOAA Chart: 11521 Latitude: 32° 57.5' N ( 32.95830)
USGS Quad: STALLSVILLE Longitude: 80° 12.2' W ( -80.20330)
To reach the tidal bench marks from the intersection of S.C. Highway 7 and S.C.
Highway 61 NW of Charleston, proceed NW on S.C. Highway 61 for 24.5 km (15.2 mi)
to the Y-intersection of S.C. Highways 61 and 165, then turn right onto and
proceed north on S.C. Highway 165 for 1.6 km (1.0 mi) to Bacon Bridge, the
second bridge past the junction of S.C. Highways 165 and 61. The bench marks
are located north and west of the bridge, and the gage and staff were located on
the west side of the bridge.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 4531 A 1976
DESIGNATION: 866 4531 A TIDAL
MONUMENTATION: Tidal Station disk VM#: 4044
AGENCY: National Ocean Survey (NOS) IDB PID#: CK3053
SETTING CLASSIFICATION: Copper clad steel rod OPUS PID:
LATITUDE: 32° 57.5' N ( 32.95830) LONGITUDE: 80° 12.1' W ( -80.20170)
The primary bench mark is a disk set in a clearing west of the bridge 18.75 m
(61.5 ft) west of SW bridge abutment, 13.87 m (45.5 ft) west of 0.91 m (3.0 ft)
diameter oak tree, and 3.51 m (11.5 ft) NNW of 0.91 m (3.0 ft) diameter dead oak
tree. The bench mark is set at ground level, crimped to the top of a
copper-clad steel rod driven 3.7 m (12 ft) to refusal, encased in a 4-inch PVC
pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8664531 PUBLICATION DATE: 04/01/2004
Name: BACON BRIDGE, ASHLEY RIVER
SC
NOAA Chart: 11521 Latitude: 32° 57.5' N ( 32.95830)
USGS Quad: STALLSVILLE Longitude: 80° 12.2' W ( -80.20330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4531 C 1976
DESIGNATION: 866 4531 C TIDAL
MONUMENTATION: Tidal Station disk VM#: 4045
AGENCY: National Ocean Survey (NOS) IDB PID#: CK3052
SETTING CLASSIFICATION: Bridge abutment OPUS PID#: CK3052
LATITUDE: 32° 57.5' N ( 32.95830) LONGITUDE: 80° 12.0' W ( -80.20000)
The bench mark is a disk set flush in bridge abutment, located in NE bridge
abutment, 65 m (213 ft) south of bench mark 4531 D 1976, 7.53 m (24.7 ft) east
of centerline of S.C. Highway 165, 4.24 m (13.9 ft) SW of power pole #37687, and
0.24 m (0.8 ft) above ground level.
BENCH MARK STAMPING: 4531 D 1976
DESIGNATION: 866 4531 D TIDAL
MONUMENTATION: Tidal Station disk VM#: 4046
AGENCY: National Ocean Survey (NOS) IDB PID#: CK3051
SETTING CLASSIFICATION: Copper clad steel rod OPUS PID:
LATITUDE: 32° 57.5' N ( 32.95830) LONGITUDE: 80° 12.0' W ( -80.20000)
The bench mark is a disk set north of the bridge on S.C. Highway 165, 10.27 m
(33.7 ft) east of centerline of S.C. Highway 165, and 1.31 m (4.3 ft) west of
power pole #92920. The bench mark is set 3 cm (0.1 ft) above ground level,
crimped to the top of a copper-clad steel rod driven 4.3 m (14 ft) to refusal,
encased in a 4-inch PVC pipe and concrete kickblock. NOTE: Mark not found in
2003 by US Power Squadron.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8664531 PUBLICATION DATE: 04/01/2004
Name: BACON BRIDGE, ASHLEY RIVER
SC
NOAA Chart: 11521 Latitude: 32° 57.5' N ( 32.95830)
USGS Quad: STALLSVILLE Longitude: 80° 12.2' W ( -80.20330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4531 E 1976
DESIGNATION: 866 4531 E TIDAL
MONUMENTATION: Tidal Station disk VM#: 4047
AGENCY: National Ocean Survey (NOS) IDB PID#: CK3050
SETTING CLASSIFICATION: Copper clad steel rod OPUS PID:
LATITUDE: 32° 57.5' N ( 32.95830) LONGITUDE: 80° 12.0' W ( -80.20000)
The bench mark is a disk set on the west side of S.C. Highway 165, north of the
bridge 24.99 m (82.0 ft) east of NE corner of concrete block house, 8.14 m (26.7
ft) north of paved driveway leading to house, 7.19 m (23.6 ft) NE of centerline
of S.C. Highway 165, and 3.96 m (13.0 ft) SE of power pole #8002. The bench
mark is set at ground level, crimped to the top of a copper-clad steel rod
driven 6.4 m (21 ft) to refusal, and encased in a 4-inch PVC pipe and concrete
kickblock. NOTE: Mark not found in 2003 by US Power Squadron; could not find
power pole 8002 or cement block building.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8664531 PUBLICATION DATE: 04/01/2004
Name: BACON BRIDGE, ASHLEY RIVER
SC
NOAA Chart: 11521 Latitude: 32° 57.5' N ( 32.95830)
USGS Quad: STALLSVILLE Longitude: 80° 12.2' W ( -80.20330)
T I D A L D A T U M S
Tidal datums at BACON BRIDGE, ASHLEY RIVER based on:
LENGTH OF SERIES: 2 MONTHS
TIME PERIOD: February 1977 - March 1977
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8665530 CHARLESTON, COOPER RIVER ENTRANCE
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 0.716
MEAN HIGH WATER MHW = 0.647
MEAN TIDE LEVEL MTL = 0.328
MEAN SEA LEVEL MSL = 0.294
MEAN LOW WATER MLW = 0.008
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum NAVD88 = -0.373
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
4531 A 1976 2.117 1.470
4531 C 1976 4.705 4.058
4531 D 1976 4.600 3.953
4531 E 1976 6.532 5.885
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8664531 PUBLICATION DATE: 04/01/2004
Name: BACON BRIDGE, ASHLEY RIVER
SC
NOAA Chart: 11521 Latitude: 32° 57.5' N ( 32.95830)
USGS Quad: STALLSVILLE Longitude: 80° 12.2' W ( -80.20330)
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 NGS's Integrated Data Base (IDB PID)
provides geodetic datum based on traditionally leveled and bluebooked ties to
the National Spatial Reference System(NSRS) https://www.ngs.noaa.gov/datasheets/.
The NGS Online Positioning User Service (OPUS PID) provides geodetic datum based
on GPS position & tie it to the NSRS https://www.ngs.noaa.gov/OPUS/.
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.