Superseded Bench Mark Sheet for 8677344, St.Simons Island GA

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:  09/21/2000
Station ID: 8677344                                SUPERCEDED DATE:   04/21/2003
Name:       ST SIMONS LIGHTHOUSE, ST SIMONS ISLAND            
            GEORGIA
NOAA Chart: 11506                                  Latitude:         31°  7.9' N
USGS Quad:  BRUNSWICK EAST                         Longitude:        81° 23.8' W


To reach the tidal bench marks from the intersection of U.S. Highway 17 and the
Torras Causeway toll road in Brunswick, proceed 6.6 km (4.1 mi) east on the
causeway to St. Simons Island, right (SSE) onto Kings Way for 3.5 km (2.2 mi) to
Mallory Street, right on Mallory Street for 0.3 km (0.2 mi) to end at Neptune
Park and a pier.  The bench marks are located between the pier and St. Simons
Lighthouse.  The tide gage and staff were located on the SE corner of the pier.


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


                 PRIMARY BENCH MARK STAMPING:   
                         DESIGNATION:          TIDAL 1
                         ALIAS:                867 7344 NO STAMPING 1

MONUMENTATION:           Chiseled Cross                            VM#:     4929
AGENCY:                  US Coast and Geodetic Survey (USC&GS)     PID#:  BR0079
SETTING CLASSIFICATION:  Foundation stones


The primary bench mark is the center of a chiseled cross cut near the top of the
vertical face of the upper course of foundation stones on the west side of St.
Simons Lighthouse, nearly under the northern end of the windows, 0.30 m (1 ft)
south of bench mark NO 2, and about 0.61 m (2.0 ft) above ground level.  NOTE:
The benchmark is historically referred to as I 1888.



                         BENCH MARK STAMPING:  NO 2
                         DESIGNATION:          TIDAL 2

MONUMENTATION:           Tidal Station disk                        VM#:     4924
AGENCY:                  US Coast and Geodetic Survey (USC&GS)     PID#:  BR0078
SETTING CLASSIFICATION:  Lighthouse foundation


The bench mark is a disk set vertically in the base on the west side of St.
Simons Lighthouse, 0.30 m (1 ft) north of and 0.09 m (0.3 ft) below bench mark
TIDAL 1, and 1 m (2 ft) above ground level.  NOTE: The benchmark is historically
referred to as No 2 1924.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  5

                                                   PUBLICATION DATE:  09/21/2000
Station ID: 8677344                                SUPERCEDED DATE:   04/21/2003
Name:       ST SIMONS LIGHTHOUSE, ST SIMONS ISLAND            
            GEORGIA
NOAA Chart: 11506                                  Latitude:         31°  7.9' N
USGS Quad:  BRUNSWICK EAST                         Longitude:        81° 23.8' W


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


                         BENCH MARK STAMPING:  NO 3 1973
                         DESIGNATION:          867 7344 TIDAL 3

MONUMENTATION:           Tidal Station disk                        VM#:     4926
AGENCY:                  National Ocean Survey (NOS)               PID#:  AI9971
SETTING CLASSIFICATION:  Concrete sidewalk


The bench mark is a disk set flush in the concrete sidewalk near the NW corner
of the St. Simons pier, 5.38 m (17.7 ft) NNW of the NW corner concrete pier roof
post, 2.69 m (8.83 ft) NNE of the south edge of the sidewalk at the shoreline,
and 0.36 m (1.18 ft) ESE of the west edge of the sidewalk.



                         BENCH MARK STAMPING:  NO 4 1973
                         DESIGNATION:          867 7344 TIDAL 4

MONUMENTATION:           Tidal Station disk                        VM#:     4927
AGENCY:                  National Ocean Survey (NOS)               PID#:  AI9972
SETTING CLASSIFICATION:  Concrete monument


The bench mark is a disk set flush in a concrete sidewalk near a mini-golf park
on the east side of the pier parking lot, 10.73 m (35.2 ft) NE of the base of a
large oak tree surrounded by a wooden deck, 7.42 m (24.3 ft) NW of the NW corner
of a pavillion, and 6.07 m (19.9 ft) WNW of the east edge of the sidewalk.



                         BENCH MARK STAMPING:  NO 5 1973
                         DESIGNATION:          867 7344 TIDAL 5

MONUMENTATION:           Tidal Station disk                        VM#:     4928
AGENCY:                  National Ocean Survey (NOS)               PID#:  AI9973
SETTING CLASSIFICATION:  Concrete sidewalk


The bench mark is a disk set in the southern end of a U-shaped concrete sidewalk
at the southern end of a parking area between the casino and the Chamber of
Commerce/Library and 1 m (4 ft) north of a power pole.

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

                                                   PUBLICATION DATE:  09/21/2000
Station ID: 8677344                                SUPERCEDED DATE:   04/21/2003
Name:       ST SIMONS LIGHTHOUSE, ST SIMONS ISLAND            
            GEORGIA
NOAA Chart: 11506                                  Latitude:         31°  7.9' N
USGS Quad:  BRUNSWICK EAST                         Longitude:        81° 23.8' W


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


                         BENCH MARK STAMPING:  ARP 1953
                         DESIGNATION:          ARP

MONUMENTATION:           Topographic Station disk                  VM#:    16039
AGENCY:                  US Coast and Geodetic Survey (USC&GS)     PID#:  BR0062
SETTING CLASSIFICATION:  Light pole base


The bench mark is a disk set in an abandoned light pole base on the north edge
of runway 8-26 (abandoned) at the Malcolm McKinnon Airport, 0.2 km (0.1 mi) SW
of a sharp turn in Skylane Road, 244 m (800 ft) west of runway 15-33, the fifth
abandoned light pole base west of the intersection of runways 15-33 and 8-26,
and at ground level.



                         BENCH MARK STAMPING:  ARP 2 1959
                         DESIGNATION:          ARP 2

MONUMENTATION:           Topographic Station disk                  VM#:    16040
AGENCY:                  US Coast and Geodetic Survey (USC&GS)     PID#:  BR0073
SETTING CLASSIFICATION:  Concrete monument


The bench mark is a disk set in a concrete monument in the triangle formed by
runways 8-26, the closed runway and the NE-SW taxiway at Malcolm McKinnon
Airport, 178 m (585 ft) south of the wind sock and on a line that extends from
the airport beacon through the wind sock, 24.23 m (79.5 ft) WNW of the south
edge of the middle garage door on the back side of a metal hanger, 1.04 m (3.4
ft) NNE of a fiberglass witness post, 0.58 m (1.9 ft) SSW of a metal post, and
at ground level.

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

                                                   PUBLICATION DATE:  09/21/2000
Station ID: 8677344                                SUPERCEDED DATE:   04/21/2003
Name:       ST SIMONS LIGHTHOUSE, ST SIMONS ISLAND            
            GEORGIA
NOAA Chart: 11506                                  Latitude:         31°  7.9' N
USGS Quad:  BRUNSWICK EAST                         Longitude:        81° 23.8' W


                            T I D A L   D A T U M S 


Tidal datums at ST SIMONS LIGHTHOUSE, ST SIMONS ISLAND based on:

     LENGTH OF SERIES:      1 YEAR
     TIME PERIOD:           July 1999 - June 2000
     TIDAL EPOCH:           1960-1978
     CONTROL TIDE STATION:  8670870 FORT PULASKI, SAVANNAH RIVER


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

     HIGHEST OBSERVED WATER LEVEL (09/28/1980)         =  2.856
     MEAN HIGHER HIGH WATER                     MHHW   =  2.176
     MEAN HIGH WATER                            MHW    =  2.064
     North American Vertical Datum              NAVD88 =  1.355
     MEAN SEA LEVEL                             MSL    =  1.071
     MEAN TIDE LEVEL                            MTL    =  1.064
     MEAN LOW WATER                             MLW    =  0.063
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (02/20/2000)         = -0.571

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     TIDAL 1                                     5.237    3.173
     NO 2                                        5.155    3.091
     NO 3 1973                                   4.111    2.047
     NO 4 1973                                   4.563    2.499
     NO 5 1973                                   4.261    2.197
     ARP 1953                                    5.605    3.541
     ARP 2 1959                                  6.007    3.943


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

                                                   PUBLICATION DATE:  09/21/2000
Station ID: 8677344                                SUPERCEDED DATE:   04/21/2003
Name:       ST SIMONS LIGHTHOUSE, ST SIMONS ISLAND            
            GEORGIA
NOAA Chart: 11506                                  Latitude:         31°  7.9' N
USGS Quad:  BRUNSWICK EAST                         Longitude:        81° 23.8' 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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