U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8666652 PUBLICATION DATE: 02/05/2004
Name: FOLLY RIVER, SOUTH
SC
NOAA Chart: 11522 Latitude: 32° 39.7' N ( 32.66170)
USGS Quad: JAMES ISLAND Longitude: 79° 56.7' W ( -79.94500)
To reach the tidal bench marks from the junction of State Highway 700 and State
Highway 171 (Folly Road) in James Island, proceed south on State Highway 171 for
12.31 km (7.65 mi) to the bridge over Folly River. The bench marks are located
on the bridge and along State Highway 171. The tide gage and staff were located
just west of the bridge on a wooden pier.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 6652 B 1976
DESIGNATION: 866 6652 B TIDAL
MONUMENTATION: Tidal Station disk VM#: 4330
AGENCY: National Ocean Survey (NOS) IDB PID#: CJ0441
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 32° 39.8' N ( 32.66330) LONGITUDE: 79° 56.6' W ( -79.94330)
The primary bench mark is a disk located on the east side of State Highway 171,
83.61 m (274.3 ft) north of the NE corner of the bridge, 9 m (30 ft) ENE of the
centerline of the highway, 5.79 m (19.0 ft) WSW of utility pole #33952 with a
trans- former and 7 guy wires, and 0.58 m (1.9 ft) ENE of a metal witness post.
The bench mark is set 1 m (3 ft) below the highway, crimped to the top of a
copper-clad steel rod driven 10.7 m (35 ft) to refusal, and encased in a PVC
pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8666652 PUBLICATION DATE: 02/05/2004
Name: FOLLY RIVER, SOUTH
SC
NOAA Chart: 11522 Latitude: 32° 39.7' N ( 32.66170)
USGS Quad: JAMES ISLAND Longitude: 79° 56.7' W ( -79.94500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: C-6 1974
DESIGNATION: C-6
MONUMENTATION: Survey disk VM#: 4329
AGENCY: Local Surveyor (LOCSUR) IDB PID#: CJ0443
SETTING CLASSIFICATION: Concrete abutment OPUS PID:
LATITUDE: 32° 39.8' N ( 32.66330) LONGITUDE: 79° 56.6' W ( -79.94330)
The bench mark is a disk set flush in the NE concrete abutment of the State
Highway 171 bridge over Folly River, 6.83 m (22.4 ft) east of the centerline of
State Highway 171, 1.13 m (3.7 ft) east of the east railing on the bridge, 0.21
m (0.7 ft) west of the east edge of the bridge abutment, and 0.3 m (1 ft) above
the highway.
BENCH MARK STAMPING: 6652 D 1976
DESIGNATION: 866 6652 D TIDAL
MONUMENTATION: Tidal Station disk VM#: 4331
AGENCY: National Ocean Survey (NOS) IDB PID#: CJ0439
SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID:
LATITUDE: 32° 39.8' N ( 32.66330) LONGITUDE: 79° 56.7' W ( -79.94500)
The bench mark is a disk located on the west side of State Highway 171, 11.28 m
(37.0 ft) WSW of the centerline of the highway, 8.47 m (27.8 ft) west of the
east post of the Folly Beach City Limits sign, 1.83 m (6.0 ft) NNW of utility
pole #A6434, and 0.61 m (2.0 ft) west of a metal witness post. The bench mark
is crimped to the top of a copper-clad steel rod driven 9.8 m (32 ft) to
refusal, and encased in a 5-inch PVC pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8666652 PUBLICATION DATE: 02/05/2004
Name: FOLLY RIVER, SOUTH
SC
NOAA Chart: 11522 Latitude: 32° 39.7' N ( 32.66170)
USGS Quad: JAMES ISLAND Longitude: 79° 56.7' W ( -79.94500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 6652 E 1983
DESIGNATION: 866 6652 E TIDAL
MONUMENTATION: Tidal Station disk VM#: 4332
AGENCY: National Ocean Survey (NOS) IDB PID#: CJ0442
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 32° 39.8' N ( 32.66330) LONGITUDE: 79° 56.6' W ( -79.94330)
The bench mark is a disk set in the top of a concrete monument on the west side
of State highway 171, in the median between the entrances to Mariners Cay and
Bushys Seafood Restaurant, 34.38 m (112.8 ft) WNW of Bench Mark 6652 B 1976,
32.10 m (105.3 ft) SSE of the center of the entrance doors to the restaurant,
18.56 m (60.9 ft) WSW of the centerline of the highway, 8.41 m (27.6 ft) NNW of
the centerline of the north entrance road to Mariners Cay, 3.20 m (10.5 ft) SSE
of a fire hydrant, and level with the ground. NOTE: A thorough search revealed
no evidence of the mark in 1990.
BENCH MARK STAMPING: 6652 F 1983
DESIGNATION: 866 6652 F TIDAL
MONUMENTATION: Tidal Station disk VM#: 4333
AGENCY: National Ocean Survey (NOS) IDB PID#: CJ0440
SETTING CLASSIFICATION: Concrete monument OPUS PID:
LATITUDE: 32° 39.8' N ( 32.66330) LONGITUDE: 79° 56.6' W ( -79.94330)
The bench mark is a disk set in the top of a concrete monument on the east side
of State Highway 171, near the marsh, 58.49 m (191.9 ft) NNW of Bench Mark 6652
B 1976, 10.24 m (33.6 ft) NW of the anchor line to a utility pole, 9.42 m (30.9
ft) ENE of the centerline of the highway, 8.17 m (26.8 ft) west of a utility
pole, 0.61 m (2.0 ft) west of a metal witness post, and 1 m (3 ft) below the
highway.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8666652 PUBLICATION DATE: 02/05/2004
Name: FOLLY RIVER, SOUTH
SC
NOAA Chart: 11522 Latitude: 32° 39.7' N ( 32.66170)
USGS Quad: JAMES ISLAND Longitude: 79° 56.7' W ( -79.94500)
T I D A L D A T U M S
Tidal datums at FOLLY RIVER, SOUTH based on:
LENGTH OF SERIES: 1 YEAR
TIME PERIOD: February 1977 - January 1978
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:
HIGHEST OBSERVED WATER LEVEL (06/01/1977) = 2.351
MEAN HIGHER HIGH WATER MHHW = 1.778
MEAN HIGH WATER MHW = 1.662
North American Vertical Datum NAVD88 = 0.986
MEAN SEA LEVEL MSL = 0.901
MEAN TIDE LEVEL MTL = 0.859
MEAN LOW WATER MLW = 0.056
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (11/22/1976) = -0.515
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
6652 B 1976 2.482 0.820
C-6 1974 4.000 2.338
6652 D 1976 2.698 1.036
6652 E 1983 3.147 1.485
6652 F 1983 2.121 0.459
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8666652 PUBLICATION DATE: 02/05/2004
Name: FOLLY RIVER, SOUTH
SC
NOAA Chart: 11522 Latitude: 32° 39.7' N ( 32.66170)
USGS Quad: JAMES ISLAND Longitude: 79° 56.7' W ( -79.94500)
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.