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

                                                                                
Station ID: 8665002                         PUBLICATION DATE:  05/06/2003
Name:       DRAYTON, BEES FERRY, ASHLEY RIVER                 
            SC
NOAA Chart: 11524                           Latitude:   32° 50.9' N (  32.84830)
USGS Quad:  JOHNS ISLAND                    Longitude:  80°  3.1' W ( -80.05170)


To reach the tidal bench marks from the intersection of State Highways 61 and 7,
proceed NW on State Highway 61 for 6.1 km (3.8 mi) to North Lander Lane
(entrance to Drayton-on-the-Ashley Housing Development), turn right and go NE
for one block to Limestone Boulevard, turn right and go SE for one block to
Brevard Street, turn left onto Brevard Street and continue to its end at Ashley
River.  The bench marks are located across a small slough SE from the dock and
along the railroad.  The tide gage and staff were at the NW end of the dock
owned by Drayton Athletic Association.


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


                 PRIMARY BENCH MARK STAMPING:  NO 1 1933
                         DESIGNATION:          866 5002 TIDAL 1

MONUMENTATION:           Tidal Station disk                    VM#:         4130
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  CK1342
SETTING CLASSIFICATION:  Concrete pier                         OPUS PID:        
LATITUDE:   32° 50.9' N (  32.84830)          LONGITUDE:  80°  3.0' W ( -80.05000)


The primary bench mark is a disk set in the concrete top at the NW end of the NE
pier of the railroad drawbridge over Ashley River, 12.19 m (40.0 ft) NE of bench
mark A 17 1933 5.538, 3 m (10 ft) NW of the NW railroad track, and 2.29 m (7.5
ft) below the track.

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

                                                                                
Station ID: 8665002                         PUBLICATION DATE:  05/06/2003
Name:       DRAYTON, BEES FERRY, ASHLEY RIVER                 
            SC
NOAA Chart: 11524                           Latitude:   32° 50.9' N (  32.84830)
USGS Quad:  JOHNS ISLAND                    Longitude:  80°  3.1' W ( -80.05170)


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


                         BENCH MARK STAMPING:  A 17 1933 5.538
                         DESIGNATION:          A17

MONUMENTATION:           Bench Mark disk                       VM#:         4129
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  CK1343
SETTING CLASSIFICATION:  Concrete pier                         OPUS PID:        
LATITUDE:   32° 50.9' N (  32.84830)          LONGITUDE:  80°  3.0' W ( -80.05000)


The bench mark is a disk set in the top center concrete pier on the draw portion
of the drawbridge, 6 m (20 ft) NE of the tower control house, 2 m (6 ft) NW of
the centerline of the NW track, and 2 m (7 ft) below the track.



                         BENCH MARK STAMPING:  NO 3 1933
                         DESIGNATION:          866 5002 TIDAL 3

MONUMENTATION:           Tidal Station disk                    VM#:         4131
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  CK1341
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID:        
LATITUDE:   32° 50.8' N (  32.84670)          LONGITUDE:  80°  3.0' W ( -80.05000)


The bench mark is a disk set in a concrete mounment at the SW end of the
railroad drawbridge over Ashley River, 19.45 m (63.8 ft) SE of bench mark NO 5
1974, 13.20 m (43.3 ft) SSW of bench mark NO 4 1974, 13 m (43 ft) south of the
south end of the drawbridge, 12.34 m (40.5 ft) ENE of a steel post with sign
ASHLEY RIVER, and 9.72 m (31.9 ft) ESE of a concrete abutment with a light
signal.  Note: The bench mark has been hit by machinery.

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

                                                                                
Station ID: 8665002                         PUBLICATION DATE:  05/06/2003
Name:       DRAYTON, BEES FERRY, ASHLEY RIVER                 
            SC
NOAA Chart: 11524                           Latitude:   32° 50.9' N (  32.84830)
USGS Quad:  JOHNS ISLAND                    Longitude:  80°  3.1' W ( -80.05170)


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


                         BENCH MARK STAMPING:  NO 4 1974
                         DESIGNATION:          866 5002 TIDAL 4

MONUMENTATION:           Tidal Station disk                    VM#:         4132
AGENCY:                  National Geodetic Survey (NGS)        IDB PID#:  CK1345
SETTING CLASSIFICATION:  Concrete abutment                     OPUS PID#: CK1345
LATITUDE:   32° 50.8' N (  32.84670)          LONGITUDE:  80°  3.0' W ( -80.05000)


The bench mark is a disk set in the SE bridge abutment at the south end of the
drawbridge, 17.19 m (56.4 ft) NE of bench mark NO 5 1974, 2 m (8 ft) east of the
SE rail of the SE track, 0.46 m (1.5 ft) NE of the edge of the concrete
abutment, and 2.01 m (6.6 ft) below the track.



                         BENCH MARK STAMPING:  NO 5 1974
                         DESIGNATION:          866 5002 TIDAL 5

MONUMENTATION:           Tidal Station disk                    VM#:         4133
AGENCY:                  National Geodetic Survey (NGS)        IDB PID#:  CK1344
SETTING CLASSIFICATION:  Concrete foundation                   OPUS PID:        
LATITUDE:   32° 50.8' N (  32.84670)          LONGITUDE:  80°  3.0' W ( -80.05000)


The bench mark is a disk set in the top of the concrete base of signal light C,
17.31 m (56.8 ft) west of the SE bridge abutment at the south end of the
drawbridge, 13.93 m (45.7 ft) SW of the SW bridge abutment, 2.50 m (8.2 ft) NW
of the NW rail of the NW track, and 0.76 m (2.5 ft) above the ground.

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

                                                                                
Station ID: 8665002                         PUBLICATION DATE:  05/06/2003
Name:       DRAYTON, BEES FERRY, ASHLEY RIVER                 
            SC
NOAA Chart: 11524                           Latitude:   32° 50.9' N (  32.84830)
USGS Quad:  JOHNS ISLAND                    Longitude:  80°  3.1' W ( -80.05170)


                            T I D A L   D A T U M S 


Tidal datums at DRAYTON, BEES FERRY, ASHLEY RIVER based on:

     LENGTH OF SERIES:      12 MONTHS
     TIME PERIOD:           July 1988 - June 1989
     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:

     HIGHEST OBSERVED WATER LEVEL (03/09/1989)         =  2.289
     MEAN HIGHER HIGH WATER                     MHHW   =  1.892
     MEAN HIGH WATER                            MHW    =  1.795
     North American Vertical Datum              NAVD88 =  1.027
     MEAN SEA LEVEL                             MSL    =  1.009
     MEAN TIDE LEVEL                            MTL    =  0.928
     MEAN LOW WATER                             MLW    =  0.060
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (04/07/1989)         = -0.607

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     NO 1 1933                                   2.497    0.702
     A 17 1933 5.538                             2.397    0.602
     NO 3 1933                                   3.564    1.769
     NO 4 1974                                   4.250    2.455
     NO 5 1974                                   5.101    3.306


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

                                                                                
Station ID: 8665002                         PUBLICATION DATE:  05/06/2003
Name:       DRAYTON, BEES FERRY, ASHLEY RIVER                 
            SC
NOAA Chart: 11524                           Latitude:   32° 50.9' N (  32.84830)
USGS Quad:  JOHNS ISLAND                    Longitude:  80°  3.1' W ( -80.05170)


                             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.