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Superseded Bench Mark Sheet for 8666616, SOUTH EDISTO RIVER AT DAWHOO RIVER SC

Present Epoch

Printable version

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  5

                                                   PUBLICATION DATE:  08/04/1986
Station ID: 8666616                                SUPERCEDED DATE:   04/21/2003
Name:       SOUTH EDISTO RIVER AT DAWHOO                      
            SOUTH CAROLINA
NOAA Chart: 11517                                  Latitude:         32° 39.4' N
USGS Quad:  FENWICK                                Longitude:        80° 23.5' W


To reach the tidal bench marks from the intersection of U.S. Highway 17 and
State Highway 162, travel 11.1 miles (17.9 km) south on State Highway 162 to the
intersection of State Highway 164, bear left onto State Highway 164 and travel
2.4 miles (3.9 km) to State Highway 174, proceed through the intersection and
travel 3.2 miles (5.1 km) on State Highway 164 to the end of the pavement,
continue 1.0 mile (1.6 km) on a dirt road to State Road S-10-38, bear left past
the entrance to Hutton Plantation, travel 0.3 mile (0.5 km), bear left past the
entrance to Willtown Bluff and continue 0.5 mile (0.8 km) to Willtown Bluff Boat
Landing.  By boat, travel 3.0 miles (4.8 km) south on South Edisto River to the
gage site on the north bank of a turn in the river.  The bench marks are located
on a small dike, formerly the site of a fishing camp.  The tide gage and staff
were located 0.3 mile (0.5 km) west of the mouth of Dawhoo River, 200 feet (61
m) east of the mouth of a small creek, and 100 feet (30 m) from berm line. 
NOTE: This station can only be reached by boat.


                         T I D A L   B E N C H   M A R K S


                 PRIMARY BENCH MARK STAMPING:  6616 A 1979

MONUMENTATION:           Survey Disk                               VM#:     4324
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Stainless Steel Rod


The bench mark is at the southern end of the westernmost dike, 47.4 feet (14.4
m) SSW of Bench Mark 6616 B 1979, 28.9 feet (8.8 m) SSE of a 2.0-foot (0.6 m)
diameter cypress tree on the east bank of the small creek, and 2.6 feet (0.8 m)
NW of a witness post.  The bench mark is crimped to the top of a stainless steel
rod driven 27 feet (8 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  2 of  5

                                                   PUBLICATION DATE:  08/04/1986
Station ID: 8666616                                SUPERCEDED DATE:   04/21/2003
Name:       SOUTH EDISTO RIVER AT DAWHOO                      
            SOUTH CAROLINA
NOAA Chart: 11517                                  Latitude:         32° 39.4' N
USGS Quad:  FENWICK                                Longitude:        80° 23.5' W


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  6616 B 1979

MONUMENTATION:           Survey Disk                               VM#:     4325
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Stainless Steel Rod


The bench mark is at the western end of a small dike near the steep creek bank
where many bricks are scattered about, 33.2 feet (10.1 m) SSW of a 3.0-foot (0.9
m) diameter cypress tree, 23.5 feet (7.2 m) NNE of a 2.0-foot (0.6 m) diameter
cypress tree, 7.4 feet (2.3 m) SE of the creek bank, and 3.9 feet (1.2 m) south
of a witness post.  The bench mark is crimped to the top of a stainless steel
rod driven 27 feet (8 m) to refusal, encased in a PVC pipe and concrete
kickblock, and at ground level.



                         BENCH MARK STAMPING:  6616 C 1979

MONUMENTATION:           Survey Disk                               VM#:     4326
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Stainless Steel Rod


The bench mark is at the easternmost of two dikes running north-south, 42.3 feet
(12.9 m) south of Bench Mark HOS 2 1933, 16.1 feet (4.9 m) south of a 0.3-foot
(0.1 m) diameter water oak tree, 3.2 feet (1.0 m) north of a 0.3-foot (0.1 m)
diamter water oak tree, and 1.6 feet (0.5 m) SW of a witness post.  The bench
mark is crimped to the top of a stainless steel rod driven 24 feet (7 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:  08/04/1986
Station ID: 8666616                                SUPERCEDED DATE:   04/21/2003
Name:       SOUTH EDISTO RIVER AT DAWHOO                      
            SOUTH CAROLINA
NOAA Chart: 11517                                  Latitude:         32° 39.4' N
USGS Quad:  FENWICK                                Longitude:        80° 23.5' W


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  HOS 1 1933

MONUMENTATION:           Survey Disk                               VM#:     4327
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Monument


The bench mark is set flush in a concrete monument on a small dike running
east-west, 41.8 feet (12.7 m) east of Bench Mark 6616 B 1979, 20.0 feet (6.1 m)
west of a 1.0-foot (0.3 m) diameter cedar tree, 5.2 feet (1.6 m) north of the
south edge of the dike, 4.1 feet (1.2 m) south of the north edge of the dike,
and 0.2 foot (0.1 m) above ground level.



                         BENCH MARK STAMPING:  HOS 2 1933

MONUMENTATION:           Survey Disk                               VM#:     4328
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Monument


The bench mark is set flush in a concrete monument at the junction of two dikes
running east-west and north-south, 34.4 feet (10.5 m) east of Bench Mark HOS 1
1933, 13.9 feet (4.2 m) east of a 1.0-foot (0.3 m) diameter cedar tree, 9.7 feet
(3.0 m) NE of the south edge of the dike, 5.9 feet (1.8 m) NE of the south edge
of the dike, and 0.2 foot (0.1 m) above ground level.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  5

                                                   PUBLICATION DATE:  08/04/1986
Station ID: 8666616                                SUPERCEDED DATE:   04/21/2003
Name:       SOUTH EDISTO RIVER AT DAWHOO                      
            SOUTH CAROLINA
NOAA Chart: 11517                                  Latitude:         32° 39.4' N
USGS Quad:  FENWICK                                Longitude:        80° 23.5' W


                            T I D A L   D A T U M S 


Tidal datums at SOUTH EDISTO RIVER AT DAWHOO based on:

     LENGTH OF SERIES:      5 MONTHS
     TIME PERIOD:           APRIL-AUGUST 1979
     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 (09/04/1979)         =   9.47
     MEAN HIGHER HIGH WATER                     MHHW   =   6.61
     MEAN HIGH WATER                            MHW    =   6.34
     MEAN TIDE LEVEL                            MTL    =   3.28
     MEAN LOW WATER                             MLW    =   0.22
     MEAN LOWER LOW WATER                       MLLW   =   0.00
     LOWEST  OBSERVED WATER LEVEL (04/10/1979)         =  -1.06



Bench Mark Elevation Information                In FEET above:

     Stamping or Designation                    MLLW        MHW

     6616 A 1979                                 7.22      0.88
     6616 B 1979                                 8.12      1.78
     6616 C 1979                                 8.00      1.66
     HOS 1 1933                                  7.88      1.54
     HOS 2 1933                                  9.27      2.93


                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  5

                                                   PUBLICATION DATE:  08/04/1986
Station ID: 8666616                                SUPERCEDED DATE:   04/21/2003
Name:       SOUTH EDISTO RIVER AT DAWHOO                      
            SOUTH CAROLINA
NOAA Chart: 11517                                  Latitude:         32° 39.4' N
USGS Quad:  FENWICK                                Longitude:        80° 23.5' 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.

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Revised: 08/08/2018
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