Superseded Bench Mark Sheet for 8667411, LOBECO, WHALE BRANCH, COOSAW RIVER SC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:  10/31/1985
Station ID: 8667411                                SUPERCEDED DATE:   04/21/2003
Name:       LOBECO, WHALE BRANCH, COOSAW RIVER                
            SOUTH CAROLINA
NOAA Chart: 11519                                  Latitude:         32° 34.4' N
USGS Quad:  BENNETTS POINT                         Longitude:        80° 44.7' W


To reach the tidal bench marks from the intersection of U.S. Highway 21 and
State Highway 116 at the Marine Corps Air Station entrance, proceed north 6.0
miles (9.7 km) on U.S. Highway 21 to the J. V. Dunbar Sr. Memorial Bridge over
Whale Branch.  The bench marks are located in the median of U.S. Highway 21
leading south toward Beaufort.  The tide gage and staff were located on the
fender pilings on the east side of the bridge.


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


                 PRIMARY BENCH MARK STAMPING:  J 107 1962

MONUMENTATION:           Survey Disk                               VM#:     6761
AGENCY:                                                            PID#:  CK1429
SETTING CLASSIFICATION:  Bridge Abutment


The bench mark is set flush in the SW abutment of the J. V. Dunbar Sr. Memori-
al Bridge, 22.8 feet (6.9 m) west of the SE corner of the bridge, 16.0 feet (4.9
m) NE of utility pole #144553, and 12.5 feet (3.8 m) west of the centerline of
the northbound lane.



                         BENCH MARK STAMPING:  7411 B 1977

MONUMENTATION:           Survey Disk                               VM#:     6762
AGENCY:                                                            PID#:  CK2200
SETTING CLASSIFICATION:  Galvanized Steel Rod


The bench mark is 370.0 feet (112.8 m) SSW of Bench Mark J 107 1962, 357.0 feet
(108.8 m) north of Bench Mark 7411 C 1977, 22.0 feet (6.7 m) WNW of the
centerline of the northbound lane, and 2.1 feet (0.6 m) east of a witness post. 
The bench mark is at ground level, crimped to a steel rod driven 38 feet (12 m)
to refusal, and 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

                                                   PUBLICATION DATE:  10/31/1985
Station ID: 8667411                                SUPERCEDED DATE:   04/21/2003
Name:       LOBECO, WHALE BRANCH, COOSAW RIVER                
            SOUTH CAROLINA
NOAA Chart: 11519                                  Latitude:         32° 34.4' N
USGS Quad:  BENNETTS POINT                         Longitude:        80° 44.7' W


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


                         BENCH MARK STAMPING:  7411 C 1977

MONUMENTATION:           Survey Disk                               VM#:     6763
AGENCY:                                                            PID#:  CK2201
SETTING CLASSIFICATION:  Galvanized Steel Rod


The bench mark is 358.0 feet (109.1 m) north of Bench Mark 7411 F 1982, 357.0
feet (108.8 m) south of Bench Mark 7411 B 1977, 21.0 feet ((6.4 m) west of the
centerline of the northbound lane, and 1.6 feet (0.5 m) east of a witness post. 
The bench mark is at ground level, crimped to a steel rod driven 30 feet (9 m)
to refusal, and encased in a 4-inch PVC pipe and concrete kickblock.



                         BENCH MARK STAMPING:  7411 E 1977

MONUMENTATION:           Survey Disk                               VM#:     6764
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Galvanized Steel Rod


The bench mark is at the northern end of the second median south of the J. V.
Dunbar Sr. Memorial Bridge, 35.7 feet (10.9 m) east of the centerline of the
southbound lane, 33.0 feet (10.1 m) west of the centerline of the northbound
lane, and 20.5 feet (6.2 m) NE of a metal drain in the median.  The bench mark
is at ground level, crimped to a steel rod driven 30 feet (9 m) to refusal, and
encased in a 4-inch PVC pipe and concrete kickblock.



                         BENCH MARK STAMPING:  7411 F 1982

MONUMENTATION:           Survey Disk                               VM#:     6765
AGENCY:                                                            PID#:  CK2202
SETTING CLASSIFICATION:  Concrete Monument


The bench mark is 358.0 feet (109.1 m) south of Bench Mark 7411 C 1977, 72.5
feet (22.1 m) east of the centerline of the southbound lane, 26.0 feet (7.9 m)
west of the centerline of the northbound lane, and 2.4 feet (0.7 m) west of a
witness post.  The bench mark is at ground level.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  5

                                                   PUBLICATION DATE:  10/31/1985
Station ID: 8667411                                SUPERCEDED DATE:   04/21/2003
Name:       LOBECO, WHALE BRANCH, COOSAW RIVER                
            SOUTH CAROLINA
NOAA Chart: 11519                                  Latitude:         32° 34.4' N
USGS Quad:  BENNETTS POINT                         Longitude:        80° 44.7' W


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


                         BENCH MARK STAMPING:  7411 G 1982

MONUMENTATION:           Survey Disk                               VM#:     6771
AGENCY:                                                            PID#:  CK4352
SETTING CLASSIFICATION:  Stainless Steel Rod


The bench mark is 296.1 feet (90.3 m) SSW of Bench Mark 7411 F 1982, 53.0 feet
(16.2 m) north of the turnaround lane between the northbound and southbound
lanes, 48.5 feet (14.8 m) ESE of the centerline of the southbound lane, 25.3
feet (7.7 m) WNW of the centerline of the northbound lane, and 1.5 feet (0.5 m)
SSW of a witness post.  The bench mark is 0.1 foot (0.03 m) below ground level,
crimped to a stainless steel rod driven 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  4 of  5

                                                   PUBLICATION DATE:  10/31/1985
Station ID: 8667411                                SUPERCEDED DATE:   04/21/2003
Name:       LOBECO, WHALE BRANCH, COOSAW RIVER                
            SOUTH CAROLINA
NOAA Chart: 11519                                  Latitude:         32° 34.4' N
USGS Quad:  BENNETTS POINT                         Longitude:        80° 44.7' W


                            T I D A L   D A T U M S 


Tidal datums at LOBECO, WHALE BRANCH, COOSAW RIVER based on:

     LENGTH OF SERIES:      12 MONTHS
     TIME PERIOD:           MARCH 1978-FEBRUARY 1979
     TIDAL EPOCH:           1960-1978
     CONTROL TIDE STATION:  8667999 BEAUFORT


Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:

     HIGHEST OBSERVED WATER LEVEL (07/19/1978)         =  10.38
     MEAN HIGHER HIGH WATER                     MHHW   =   8.37
     MEAN HIGH WATER                            MHW    =   8.00
     MEAN TIDE LEVEL                            MTL    =   4.10
     MEAN LOW WATER                             MLW    =   0.20
     MEAN LOWER LOW WATER                       MLLW   =   0.00
     LOWEST  OBSERVED WATER LEVEL (01/09/1978)         =  -3.06

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In FEET above:

     Stamping or Designation                    MLLW        MHW

     J 107 1962                                 16.10      8.10
     7411 B 1977                                10.72      2.72
     7411 C 1977                                11.41      3.41
     7411 E 1977                                13.24      5.24
     7411 F 1982                                11.23      3.23
     7411 G 1982                                12.01      4.01


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

                                                   PUBLICATION DATE:  10/31/1985
Station ID: 8667411                                SUPERCEDED DATE:   04/21/2003
Name:       LOBECO, WHALE BRANCH, COOSAW RIVER                
            SOUTH CAROLINA
NOAA Chart: 11519                                  Latitude:         32° 34.4' N
USGS Quad:  BENNETTS POINT                         Longitude:        80° 44.7' 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.

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