U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
PUBLICATION DATE: 04/07/1986
Station ID: 8666467 SUPERCEDED DATE: 04/21/2003
Name: FOLLY RIVER NORTH
SOUTH CAROLINA
NOAA Chart: 11525 Latitude: 32° 40.2' N
USGS Quad: JAMES ISLAND Longitude: 79° 55.0' W
To reach the tidal bench marks from the intersection of Center Street and Ashley
Avenue East in downtown Folly Beach, proceed 1.8 miles (2.9 km) NE on Ashley
Avenue East to East 13th Street, then 0.1 mile (0.2 km) north on East 13th
Street to Tabby Drive, then west on Tabby Drive to the second house on the north
side of the street. The bench marks are located on Ashley Avenue East, along
East 13th Street, and near Tabby Drive. The tide gage and staff were located on
the pier behind the house at 1212 Tabby Drive, owned by Dr. Heinsohn.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 6467 A 1976
MONUMENTATION: Survey Disk VM#: 4312
AGENCY: PID#: CJ0462
SETTING CLASSIFICATION: Copper-clad Steel Rod
The bench mark is near a stand of trees at the western boundary of 1212 Tabby
Drive, 255.0 feet (77.7 m) SSE of the end of a concrete walkway to the dock,
91.0 feet (27.7 m) west of the SW corner of a concrete boat ramp, 69.6 feet
(21.2 m) NW of the NW corner of a brick chimney, 58.4 feet (17.8 m) NW of the NW
corner of the house, and 6.6 feet (2.0 m) east of a 1-foot (0.3 m) diameter pine
tree. The bench mark is crimped to a copper-clad steel rod driven 40 feet (12
m) to refusal, encased in a PVC pipe and concrete kickblock, and at ground
level.
BENCH MARK STAMPING: 6467 B 1976
MONUMENTATION: Survey Disk VM#: 4313
AGENCY: PID#: CJ0461
SETTING CLASSIFICATION: Copper-clad Steel Rod
The bench mark is north of the intersection of Tabby Drive and East 13th Street,
33.7 feet (10.3 m) east of the centerline of the concrete driveway at 1214 Tabby
Drive, 29.0 feet (8.8 m) north of the centerline of Tabby Drive, 13.9 feet (4.2
m) NW of a fire hydrant, and 3.6 feet (1.1 m) NW of utility pole #93967. The
bench mark is crimped to a copper-clad steel rod driven 40 feet (12 m) to
refusal, encased in a PVC pipe and concrete kickblock, and 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: 04/07/1986
Station ID: 8666467 SUPERCEDED DATE: 04/21/2003
Name: FOLLY RIVER NORTH
SOUTH CAROLINA
NOAA Chart: 11525 Latitude: 32° 40.2' N
USGS Quad: JAMES ISLAND Longitude: 79° 55.0' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6467 C 1976
MONUMENTATION: Survey Disk VM#: 4314
AGENCY: PID#: CJ0460
SETTING CLASSIFICATION: Concrete Monument
The bench mark is on the west side of East 13th Street, 34.6 feet (10.5 m) NNW
of the centerline of the most northern driveway on the west side of East 13th
Street, 28.2 feet (8.6 m) SW of the centerline of East 13th Street, 2.0 feet
(0.6 m) west of utility pole #174759 with a witness sign, 2.0 feet (0.6 m) NE of
the corner post of a 4-foot (1 m) high chainlink fence, and 0.1 foot (0.3 m)
above ground level.
BENCH MARK STAMPING: 6467 D 1976
MONUMENTATION: Survey Disk VM#: 4315
AGENCY: PID#: CJ0458
SETTING CLASSIFICATION: Copper-clad Steel Rod
The bench mark is midway between Bench Mark 6467 C 1976 and Ashley Avenue East
on the west side of East 13th Street, 70.5 feet (21.5 m) SW of a cinderblock
wall, 36.5 feet (11.1 m) NE of the centerline of a concrete driveway on the west
side of East 13th Street, 21.5 feet (6.6 m) SW of the centerline of East 13th
Street, and 5.7 feet (1.7 m) east of utility pole #93963. The bench mark is
crimped to a copper-clad steel rod driven 40 feet (12 m) to refusal, encased in
a PVC pipe and concrete kickblock, and at ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
PUBLICATION DATE: 04/07/1986
Station ID: 8666467 SUPERCEDED DATE: 04/21/2003
Name: FOLLY RIVER NORTH
SOUTH CAROLINA
NOAA Chart: 11525 Latitude: 32° 40.2' N
USGS Quad: JAMES ISLAND Longitude: 79° 55.0' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6467 E 1976
MONUMENTATION: Survey Disk VM#: 4316
AGENCY: PID#: CJ0457
SETTING CLASSIFICATION: Concrete Monument
The bench mark is south of the intersection of East 13th Street and Ashley
Avenue East, 66.9 feet (20.4 m) east of utility pole #27767, 19.1 feet (5.8 m)
SSE of the centerline of Ashley Avenue East, 17.1 feet (5.2 m) west of the
corner post of the house at 1301 Ashley Avenue East, 2.0 feet (0.6 m) NE of a
fire hydrant, and at ground level.
BENCH MARK STAMPING: 6467 F 1983
MONUMENTATION: Survey Disk VM#: 4317
AGENCY: PID#: CJ0459
SETTING CLASSIFICATION: Concrete Monument
The bench mark is near Bench Mark 6467 C 1976, 138.1 feet (42.1 m) SSE of the
centerline of Tabby Drive, 27.0 feet (8.2 m) WSW of the centerline of East 13th
Street, 4.0 feet (1.2 m) ESE of utility pole #174759 with a witness sign, 3.0
feet (0.9 m) ENE of a chain link fence, and at ground level.
BENCH MARK STAMPING: 6467 G 1983
MONUMENTATION: Survey Disk VM#: 4318
AGENCY: PID#: CJ0456
SETTING CLASSIFICATION: Concrete Monument
The bench mark is near the intersection of Ashley Avenue East and East 13th
Street, 48.2 feet (14.7 m) ENE of utility pole #93962, 19.2 feet (5.9 m) SSE of
the centerline of Ashley Avenue East, 2.0 feet (0.6 m) WNW of a fire hydrant,
and at ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
PUBLICATION DATE: 04/07/1986
Station ID: 8666467 SUPERCEDED DATE: 04/21/2003
Name: FOLLY RIVER NORTH
SOUTH CAROLINA
NOAA Chart: 11525 Latitude: 32° 40.2' N
USGS Quad: JAMES ISLAND Longitude: 79° 55.0' W
T I D A L D A T U M S
Tidal datums at FOLLY RIVER NORTH based on:
LENGTH OF SERIES: 12 MONTHS
TIME PERIOD: JANUARY-DECEMBER 1977
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 (06/01/1977) = 8.10
MEAN HIGHER HIGH WATER MHHW = 5.98
MEAN HIGH WATER MHW = 5.61
MEAN TIDE LEVEL MTL = 2.90
MEAN LOW WATER MLW = 0.18
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (12/21/1976) = -2.29
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
6467 A 1976 8.48 2.87
6467 B 1976 8.47 2.86
6467 C 1976 8.03 2.42
6467 D 1976 8.35 2.74
6467 E 1976 11.16 5.55
6467 F 1983 8.16 2.55
6467 G 1983 11.06 5.45
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
PUBLICATION DATE: 04/07/1986
Station ID: 8666467 SUPERCEDED DATE: 04/21/2003
Name: FOLLY RIVER NORTH
SOUTH CAROLINA
NOAA Chart: 11525 Latitude: 32° 40.2' N
USGS Quad: JAMES ISLAND Longitude: 79° 55.0' 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.