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Bench Mark Sheet for 8665099, I-526 BRIDGE, ASHLEY 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Superseded Epoch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Small blue map location marker Unpublished bench mark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: 8665099                         PUBLICATION DATE:  04/21/2003
Name:       I-526 BRIDGE, ASHLEY RIVER                        
            SC
NOAA Chart: 11524                           Latitude:   32° 50.2' N (  32.83670)
USGS Quad:  JOHNS ISLAND                    Longitude:  80°  1.3' W ( -80.02170)


To reach the tidal bench marks from the intersection of I-26 and I-526 in
Charleston County, proceed south on I-526 for 4.7 km (2.9 mi), then go SE on
Leeds Avenue for 0.6 km (0.35 mi), then south on a road leading to Duncan's
Marina for 0.5 km (0.3 mi).  The bench marks are in the vicinity of the marina.
The tide gage was located on the south end of the dock closest to the I-526
bridge.


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


                 PRIMARY BENCH MARK STAMPING:  5099 A 1999
                         DESIGNATION:          866 5099 A

MONUMENTATION:           Tidal Station disk                    VM#:        15999
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Sidewalk                              OPUS PID:        
LATITUDE:   32° 50.4' N (  32.84000)          LONGITUDE:  80°  1.5' W ( -80.02500)


The primary bench mark is a disk set in a sidewalk running north and south along
the concrete boat loading dock leading to finger piers at Duncan's Marina, 8.25
m (27.1 ft) SE of the light pole on the north side of the concrete boat loading
dock, 2.56 m (8.4 ft) west of the NW corner of the gas station at the end of the
boat loading dock, 1.91 m (6.3 ft) north of the south corner of the boat loading
dock, and 0.41 m (1.3 ft) SE of the NW side of the sidewalk.

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

                                                                                
Station ID: 8665099                         PUBLICATION DATE:  04/21/2003
Name:       I-526 BRIDGE, ASHLEY RIVER                        
            SC
NOAA Chart: 11524                           Latitude:   32° 50.2' N (  32.83670)
USGS Quad:  JOHNS ISLAND                    Longitude:  80°  1.3' W ( -80.02170)


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


                         BENCH MARK STAMPING:  5099 B 1999
                         DESIGNATION:          866 5099 B

MONUMENTATION:           Tidal Station disk                    VM#:        16000
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Sidewalk                              OPUS PID:        
LATITUDE:   32° 50.4' N (  32.84000)          LONGITUDE:  80°  1.5' W ( -80.02500)


The bench mark is a disk set in a sidewalk 23.26 m (76.3 ft) SW of the SW side
of Duncan's Marina Building SE door opening to the storage exit to the pier,
1.17 m (3.8 ft) SE of a bend in the chain link fence that runs north and south
along the sidewalk, 0.56 m (1.8 ft) NW of the SE side of the sidewalk, and 0.52
m (1.7 ft) north of the hand rail.



                         BENCH MARK STAMPING:  5099 C 1999
                         DESIGNATION:          866 5099 C

MONUMENTATION:           Tidal Station disk                    VM#:        16001
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Concrete slab                         OPUS PID:        
LATITUDE:   32° 50.4' N (  32.84000)          LONGITUDE:  80°  1.5' W ( -80.02500)


The bench mark is a disk located 14.94 m (49.0 ft) SE of the NW corner of a
concrete slab in front of Duncan's Marina, 9.50 m (31.1 ft) west of the SW
corner of Duncan's Marina, 0.70 m (2.3 ft) NE of the SW corner of a concrete
slab in front of Duncan's Marina, and 0.40 m (1.3 ft) NW of the SE corner of a
concrete slab in front of Duncan's Marina.

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

                                                                                
Station ID: 8665099                         PUBLICATION DATE:  04/21/2003
Name:       I-526 BRIDGE, ASHLEY RIVER                        
            SC
NOAA Chart: 11524                           Latitude:   32° 50.2' N (  32.83670)
USGS Quad:  JOHNS ISLAND                    Longitude:  80°  1.3' W ( -80.02170)


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


                         BENCH MARK STAMPING:  5099 D 1999
                         DESIGNATION:          866 5099 D

MONUMENTATION:           Tidal Station disk                    VM#:        16002
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Concrete slab                         OPUS PID:        
LATITUDE:   32° 50.4' N (  32.84000)          LONGITUDE:  80°  1.5' W ( -80.02500)


The bench mark is a disk located 18.10 m (59.4 ft) south of the SW corner of
Duncan's Marina Building, 16.60 m (54.6  ft) south of the SW corner of an
over-hang for a boat display, being the most SE support for the over-hang, 1.70
m (5.7 ft) north of light pole No. 436019, and 0.30 m (1.0 ft) south of the NE
corner of the concrete slab supporting Bellsouth phone booth.



                         BENCH MARK STAMPING:  5099 E 1999
                         DESIGNATION:          866 5099 E

MONUMENTATION:           Tidal Station disk                    VM#:        16003
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Concrete slab                         OPUS PID:        
LATITUDE:   32° 50.4' N (  32.84000)          LONGITUDE:  80°  1.5' W ( -80.02500)


The bench mark is a disk located 15.80 m (51.8 ft) south of the SE corner of the
workshop at Duncan's Marina Building, 9.10 m (29.9 ft) NW of the NE corner of
Duncan's Marina Building, 4.90 m (16.0 ft) SW of the centerline of the driveway
in front of Duncan's Marina, 2.20 m (7.2 ft) east of the center of the double
doors leading to the boat show room at Duncan's Marina, 0.32 m (1.05 ft) SW of
the sidewalk that runs north and south in front of Duncan's Marina.

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

                                                                                
Station ID: 8665099                         PUBLICATION DATE:  04/21/2003
Name:       I-526 BRIDGE, ASHLEY RIVER                        
            SC
NOAA Chart: 11524                           Latitude:   32° 50.2' N (  32.83670)
USGS Quad:  JOHNS ISLAND                    Longitude:  80°  1.3' W ( -80.02170)


                            T I D A L   D A T U M S 


Tidal datums at I-526 BRIDGE, ASHLEY RIVER based on:

     LENGTH OF SERIES:      6 Months
     TIME PERIOD:           November 1999 - April 2000
     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:

     MEAN HIGHER HIGH WATER                     MHHW   =  1.899
     MEAN HIGH WATER                            MHW    =  1.796
     MEAN SEA LEVEL                             MSL    =  1.003
     MEAN TIDE LEVEL                            MTL    =  0.930
     MEAN LOW WATER                             MLW    =  0.064
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     5099 A 1999                                 2.443    0.647
     5099 B 1999                                 2.972    1.176
     5099 C 1999                                 3.075    1.279
     5099 D 1999                                 3.217    1.421
     5099 E 1999                                 3.078    1.282


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

                                                                                
Station ID: 8665099                         PUBLICATION DATE:  04/21/2003
Name:       I-526 BRIDGE, ASHLEY RIVER                        
            SC
NOAA Chart: 11524                           Latitude:   32° 50.2' N (  32.83670)
USGS Quad:  JOHNS ISLAND                    Longitude:  80°  1.3' W ( -80.02170)


                             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 8665099 I-526 BRIDGE, ASHLEY RIVER, SC

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