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Bench Mark Sheet for 8669415, U.S. HIGHWAY 17, LITTLE BACK RIVER SC

Superseded Epoch

Large map location marker Station Location
Small red map location marker Published bench mark
Small blue map location marker Unpublished bench mark

Bench mark positions only appear on the map if their coordinates in the CO-OPS database are at the precision of degrees/minutes/seconds/and tenths of seconds. If the coordinates are less precise, the mark will not appear.

Printable version

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

                                                                                
Station ID: 8669415                         PUBLICATION DATE:  03/09/2004
Name:       U.S. HIGHWAY 17, LITTLE BACK RIVER                
            SC
NOAA Chart: 11514                           Latitude:   32°  9.9' N (  32.16500)
USGS Quad:  PORT WENTWORTH                  Longitude:  81°  7.8' W ( -81.13000)


To reach the tidal bench marks from the intersection of U.S. Highway 17 (North
Coastal Highway/ State Route 25/170)) and the east end of the James P. Houlihan
Bridge over the Savannah River in Port Wentworth, GA, proceed north on U.S.
Highway 17/North Coastal Highway for 4.0 km (2.5 mi) to the bridge over Little
Back River, at the state line.  The bench marks are located on the bridge and
east along North Coastal Highway.  The tide gage and staff were located on the
south side of the bridge.


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


                 PRIMARY BENCH MARK STAMPING:  9415 E 1980
                         DESIGNATION:          866 9415 E TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         4645
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Unspecified rod                       OPUS PID:        
LATITUDE:   32°  9.9' N (  32.16500)          LONGITUDE:  81°  7.8' W ( -81.13000)


The primary bench mark is a disk located 99.67 m (327.0 ft) ENE of bench mark
9415 F 1980, 5.67 m (18.6 ft) north of the centerline of U.S. Highway 17, 2.47 m
(8.1 ft) north of the north edge of U.S. Highway 17, and 1.04 m (3.4 ft) SSE of
a metal sign post "55 The Law".  The bench mark is crimped to the top of an
unspecified rod driven 12.8 m (42 ft) 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

                                                                                
Station ID: 8669415                         PUBLICATION DATE:  03/09/2004
Name:       U.S. HIGHWAY 17, LITTLE BACK RIVER                
            SC
NOAA Chart: 11514                           Latitude:   32°  9.9' N (  32.16500)
USGS Quad:  PORT WENTWORTH                  Longitude:  81°  7.8' W ( -81.13000)


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


                         BENCH MARK STAMPING:  1934 NO 1 BACK
                         DESIGNATION:          BACK RM 1

MONUMENTATION:           Tidal Station disk                    VM#:         4643
AGENCY:                  US Coast & Geodetic Survey
                         (USC&GS)                                 IDB PID#:  CK5864
SETTING CLASSIFICATION:  Bridge abutment                       OPUS PID#: CK5864
LATITUDE:   32°  9.9' N (  32.16500)          LONGITUDE:  81°  7.8' W ( -81.13000)


The bench mark is a disk set flush in the concrete bridge abutment on the NE
corner of the U.S. Highway 17 bridge over Little Back River, 6.55 m (21.5 ft) SW
of the dirt canal dike on the east bank of Little Back River, 5.39 m (17.7 ft)
north of the centerline of the bridge, 0.37 m (1.2 ft) north of the centerline
of the bridge railing, 0.15 m (0.5 ft) south of the north edge of the bridge
abutment, and 0.21 m (0.7 ft) above the road bed.  NOTE:  Although this mark is
in the NGS database, the mark is outside the NGS publication area and no
descriptive text is available from NGS.



                         BENCH MARK STAMPING:  9415 C 1980
                         DESIGNATION:          866 9415 C TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         4644
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Unspecificed rod                      OPUS PID:        
LATITUDE:   32°  9.9' N (  32.16500)          LONGITUDE:  81°  7.8' W ( -81.13000)


The bench mark is a disk located 5.30 m (17.4 ft) south of the centerline of
U.S. Highway 17, 3.29 m (10.8 ft) NW of a metal reflector sign post, 1.80 m (5.9
ft) north of the edge of a rice field/swamp area, and 1.49 m (4.9 ft) NE of a
metal sign post "45 MPH".  The bench mark is crimped to the top of an
unspecified rod driven 12.8 m (42 ft) 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  3 of  5

                                                                                
Station ID: 8669415                         PUBLICATION DATE:  03/09/2004
Name:       U.S. HIGHWAY 17, LITTLE BACK RIVER                
            SC
NOAA Chart: 11514                           Latitude:   32°  9.9' N (  32.16500)
USGS Quad:  PORT WENTWORTH                  Longitude:  81°  7.8' W ( -81.13000)


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


                         BENCH MARK STAMPING:  9415 F 1980
                         DESIGNATION:          866 9415 F TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         4646
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Unspecified rod                       OPUS PID:        
LATITUDE:   32°  9.9' N (  32.16500)          LONGITUDE:  81°  7.8' W ( -81.13000)


The bench mark is a disk located 39 m (129 ft) west of the sign "Unlawful to
Litter Highways Fine up to $200", 5.12 m (16.8 ft) south of the centerline of
U.S. Highway 17, 2.16 m (7.1 ft) north of the edge of the rice field/marsh area,
and 1.40 m (4.6 ft) south of the south edge of U.S. Highway 17.  The bench mark
is crimped to the top of an unspecified rod driven 12.8 m (42 ft) to refusal,
and encased in a 4-inch PVC pipe and concrete kickblock.



                         BENCH MARK STAMPING:  9415 G 1982
                         DESIGNATION:          866 9415 G TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         4647
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID:        
LATITUDE:   32°  9.9' N (  32.16500)          LONGITUDE:  81°  7.8' W ( -81.13000)


The bench mark is a disk set flush in a concrete monument, 14.48 m (47.5 ft)
south of the centerline of U.S. Highway 17, 11.61 m (38.1 ft) west of the access
road to Savannah National Wildlife Refuge/Laurel Hill Wildlife Drive, and 9.51 m
(31.2 ft) NE of the northwestern brick column of the brick fence entrance to
Laurel Hill Wildlife Drive.

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

                                                                                
Station ID: 8669415                         PUBLICATION DATE:  03/09/2004
Name:       U.S. HIGHWAY 17, LITTLE BACK RIVER                
            SC
NOAA Chart: 11514                           Latitude:   32°  9.9' N (  32.16500)
USGS Quad:  PORT WENTWORTH                  Longitude:  81°  7.8' W ( -81.13000)


                            T I D A L   D A T U M S 


Tidal datums at U.S. HIGHWAY 17, LITTLE BACK RIVER based on:

     LENGTH OF SERIES:      10 MONTHS
     TIME PERIOD:           March 1981 - December 1981
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8670870 FORT PULASKI, SAVANNAH RIVER


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

     MEAN HIGHER HIGH WATER                     MHHW   =  2.487
     MEAN HIGH WATER                            MHW    =  2.400
     MEAN SEA LEVEL                             MSL    =  1.407
     MEAN TIDE LEVEL                            MTL    =  1.238
     MEAN LOW WATER                             MLW    =  0.076
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     9415 E 1980                                 3.525    1.125
     1934 NO 1 BACK                              4.620    2.220
     9415 C 1980                                 3.340    0.940
     9415 F 1980                                 3.521    1.121
     9415 G 1982                                 4.047    1.647


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

                                                                                
Station ID: 8669415                         PUBLICATION DATE:  03/09/2004
Name:       U.S. HIGHWAY 17, LITTLE BACK RIVER                
            SC
NOAA Chart: 11514                           Latitude:   32°  9.9' N (  32.16500)
USGS Quad:  PORT WENTWORTH                  Longitude:  81°  7.8' W ( -81.13000)


                             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.

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Products available at 8669415 U.S. HIGHWAY 17, LITTLE BACK RIVER, SC

Revised: 08/08/2018
NOAA / National Ocean Service
Web site owner: Center for Operational Oceanographic Products and Services