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

                                                                                
Station ID: 8665641                         PUBLICATION DATE:  08/14/2003
Name:       WELCHES WHARF, STONO RIVER                        
            SC
NOAA Chart: 11524                           Latitude:   32° 45.8' N (  32.76330)
USGS Quad:  STONO RIVER                     Longitude:  80°  0.1' W ( -80.00170)


To reach the tidal bench marks from the intersection of State Highways 700
(Maybank Highway) and 171 (Folly Road) on James Island, proceed west on State
Highway 700 for 2.4 km (1.5 mi) to Riverland Drive, then turn right and proceed
north on Riverland Drive for 0.8 km (0.5 mi) to Stono Drive, then turn left and
proceed west on Stono Drive for 0.2 km (0.1 mi) to the Welchs property at 151
Stono Drive.  The bench marks are near the riverbank behind two homes along
Stono Drive.  The tide gage and staff were located on the dock behind the Welchs
residence.


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


                 PRIMARY BENCH MARK STAMPING:  NO 2 1933
                         DESIGNATION:          866 5641 TIDAL 2

MONUMENTATION:           Tidal Station disk                    VM#:         4215
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  CK2273
SETTING CLASSIFICATION:  Concrete-filled tile pipe             OPUS PID:        
LATITUDE:   32° 45.8' N (  32.76330)          LONGITUDE:  80°  0.1' W ( -80.00170)


The primary bench mark is a disk set flush in a concrete-filled tile pipe behind
the residence at 151 Stono Drive, below a sloping embankment near a brick
seawall, 7.53 m (24.7 ft) SSW of a stone fence property line, 3.20 m (10.5 ft)
ESE of the seawall, 3.17 m (10.4 ft) ENE of a wooden walkway to the dock, 2.77 m
(9.1 ft) NNE of steps leading down the embankment, and at ground level.

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

                                                                                
Station ID: 8665641                         PUBLICATION DATE:  08/14/2003
Name:       WELCHES WHARF, STONO RIVER                        
            SC
NOAA Chart: 11524                           Latitude:   32° 45.8' N (  32.76330)
USGS Quad:  STONO RIVER                     Longitude:  80°  0.1' W ( -80.00170)


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


                         BENCH MARK STAMPING:  NO 3 1933
                         DESIGNATION:          866 5641 TIDAL 3

MONUMENTATION:           Tidal Station disk                    VM#:         4216
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  CK2272
SETTING CLASSIFICATION:  Concrete-filled tile pipe             OPUS PID:        
LATITUDE:   32° 45.8' N (  32.76330)          LONGITUDE:  80°  0.1' W ( -80.00170)


The bench mark is a disk set flush in a concrete-filled tile pipe behind the
residence at 151 Stono Drive, 12.77 m (41.9 ft) ESE of the brick seawall, 12.22
m (40.1 ft) NW of a large oak tree, 12.04 m (39.5 ft) NE of Bench Mark NO 2
1933, 0.70 m (2.3 ft) SSW of a woven wire fence line, and 0.15 m (0.5 ft) above
ground level.



                         BENCH MARK STAMPING:  NO 5 1974
                         DESIGNATION:          866 5641 TIDAL 5

MONUMENTATION:           Tidal Station disk                    VM#:         4217
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  CK2270
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID:        
LATITUDE:   32° 45.8' N (  32.76330)          LONGITUDE:  80°  0.1' W ( -80.00170)


The bench mark is a disk set flush in a concrete monument in the NW corner of
the property at 309 Stono Drive (Gibbs residence),16.98 m (55.7 ft) NNW of the
NW corner of the residence, 9.24 m (30.3 ft) NNE of a nautical lamp post at the
top of steps leading to the dock, 5.73 m (18.8 ft) ESE of a large twin-trunk oak
tree, and at ground level.

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

                                                                                
Station ID: 8665641                         PUBLICATION DATE:  08/14/2003
Name:       WELCHES WHARF, STONO RIVER                        
            SC
NOAA Chart: 11524                           Latitude:   32° 45.8' N (  32.76330)
USGS Quad:  STONO RIVER                     Longitude:  80°  0.1' W ( -80.00170)


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


                         BENCH MARK STAMPING:  NO 6 1974
                         DESIGNATION:          866 5641 TIDAL 6

MONUMENTATION:           Tidal Station disk                    VM#:         4218
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  CK2269
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID:        
LATITUDE:   32° 45.8' N (  32.76330)          LONGITUDE:  80°  0.1' W ( -80.00170)


The bench mark is a disk set flush in a concrete monument in the SW corner of
the property at 309 Stono Drive (Gibbs residence), 8.02 m (26.3 ft) WSW of the
SW corner of a glass-enclosed porch, 7.74 m (25.4 ft) south of the middle of
three oak trees near the end of the embankment, 2.38 m (7.8 ft) east of a lone
oak tree at the end of the embankment, and at ground level.



                         BENCH MARK STAMPING:  NO 4 1974
                         DESIGNATION:          866 5641 TIDAL 4

MONUMENTATION:           Tidal Station disk                    VM#:        17119
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  CK2271
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID:        
LATITUDE:   32° 45.8' N (  32.76330)          LONGITUDE:  80°  0.1' W ( -80.00170)


The bench mark is a disk set in a concrete monument near the river bank in the
back yard of the residence of 309 Stono Drive, 52.61 m (172.6 ft) WNW of the
approximate center of Stono Drive, 30.45 m (99.9 ft) north of the SW corner of
the House No. 309, 19.32 m (63.4 ft) NNWof the NW corner of the House No. 309,
and 3.54 m (11.6 ft) west of bench mark NO 5 1974.

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

                                                                                
Station ID: 8665641                         PUBLICATION DATE:  08/14/2003
Name:       WELCHES WHARF, STONO RIVER                        
            SC
NOAA Chart: 11524                           Latitude:   32° 45.8' N (  32.76330)
USGS Quad:  STONO RIVER                     Longitude:  80°  0.1' W ( -80.00170)


                            T I D A L   D A T U M S 


Tidal datums at WELCHES WHARF, STONO RIVER based on:

     LENGTH OF SERIES:      12 MONTHS
     TIME PERIOD:           October 1974 - September 1975
     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 (07/21/1974)         =  2.202
     MEAN HIGHER HIGH WATER                     MHHW   =  1.733
     MEAN HIGH WATER                            MHW    =  1.635
     North American Vertical Datum              NAVD88 =  0.957
     MEAN SEA LEVEL                             MSL    =  0.938
     MEAN TIDE LEVEL                            MTL    =  0.851
     MEAN LOW WATER                             MLW    =  0.067
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (02/26/1975)         = -0.615

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     NO 2 1933                                   2.750    1.115
     NO 3 1933                                   4.940    3.305
     NO 5 1974                                   6.477    4.842
     NO 6 1974                                   6.400    4.765
     NO 4 1974                                   6.212    4.577


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

                                                                                
Station ID: 8665641                         PUBLICATION DATE:  08/14/2003
Name:       WELCHES WHARF, STONO RIVER                        
            SC
NOAA Chart: 11524                           Latitude:   32° 45.8' N (  32.76330)
USGS Quad:  STONO RIVER                     Longitude:  80°  0.1' W ( -80.00170)


                             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.