U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  7

                                                                                
Station ID: 8720224                         PUBLICATION DATE:  05/16/2005
Name:       MAYPORT (FERRY DEPOT), ST JOHNS RIVER             
            FL
NOAA Chart: 11490                           Latitude:   30° 23.7' N (  30.39500)
USGS Quad:  MAYPORT                         Longitude:  81° 25.9' W ( -81.43170)





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


                 PRIMARY BENCH MARK STAMPING:  BM E.D.M. 15 MSL 1942
                         DESIGNATION:          EDM 15

MONUMENTATION:           Tidal Station disk                    VM#:        13976
AGENCY:                  National Ocean Service (NOS)          IDB PID#:  BC0458
SETTING CLASSIFICATION:  Step                                  OPUS PID:        
LATITUDE:   30° 23.7' N (  30.39500)          LONGITUDE:  81° 25.9' W ( -81.43170)


The primary bench mark is a disk set near the SW end of the bottom step at the
SE entrance to a house at the Ferry Maintenance Facility at 4610 Ocean Street,
57.30 m (187.99 ft) SE of the SE corner of the Ferry Maintenance Office, 23.29 m
(76.41 ft) SW of the center of an entrance road and gate, and 14 m (46 ft) NW of
the center of Ocean Street.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  7

                                                                                
Station ID: 8720224                         PUBLICATION DATE:  05/16/2005
Name:       MAYPORT (FERRY DEPOT), ST JOHNS RIVER             
            FL
NOAA Chart: 11490                           Latitude:   30° 23.7' N (  30.39500)
USGS Quad:  MAYPORT                         Longitude:  81° 25.9' W ( -81.43170)


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


                         BENCH MARK STAMPING:  BM E.D.M. 14 M.S.L. 1942
                         DESIGNATION:          EDM 14

MONUMENTATION:           Survey disk                           VM#:        13978
AGENCY:                  National Ocean Service (NOS)          IDB PID#:  BC0467
SETTING CLASSIFICATION:  Concrete post                         OPUS PID:        
LATITUDE:   30° 23.7' N (  30.39500)          LONGITUDE:  81° 25.9' W ( -81.43170)


The bench mark is a disk set in the top of a concrete block near a garage at the
Ferry Maintenance Facility at 4610 Ocean Street, 20.79 m (68.2 ft) SW of the SE
corner of the office building, 17.80 m (58.4 ft) WSW of a flag pole, 3.20 m
(10.5 ft) NNW of the NW corner of a garage, 0.50 m (1.6 ft) NE of a witness
post, and 0.09 m (0.30 ft) below ground level.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  7

                                                                                
Station ID: 8720224                         PUBLICATION DATE:  05/16/2005
Name:       MAYPORT (FERRY DEPOT), ST JOHNS RIVER             
            FL
NOAA Chart: 11490                           Latitude:   30° 23.7' N (  30.39500)
USGS Quad:  MAYPORT                         Longitude:  81° 25.9' W ( -81.43170)


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


                         BENCH MARK STAMPING:  B 407 1991
                         DESIGNATION:          B 407

MONUMENTATION:           Metal Rod                             VM#:        13979
AGENCY:                  National Ocean Service (NOS)          IDB PID#:  BC2546
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   30° 23.7' N (  30.39500)          LONGITUDE:  81° 25.9' W ( -81.43170)


The bench mark is a metal rod located at the Ferry Maintenance Depot at 4610
Ocean Street, on the SW side of the property, next to a chain link fence, 38.89
m (127.6 ft) SW of the SW corner of the Ferry Maintenance Office, 22.59 m (74.1
ft) NW of a chain-link fence, 18.20 m (59.7 ft) SE of the SE face of a retaining
wall, 9.51 m (31.2 ft) SW of the west corner of a garage, and 0.91 m (3.0 ft) NE
of a chain-link fence.  The datum point is the top of a stainless steel rod
driven 20.39 m (66.9 ft) to refusal, and encased in a 5-inch NGS logo cap.



                         BENCH MARK STAMPING:  0220 B 1978
                         DESIGNATION:          872 0220 B TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        13980
AGENCY:                  National Ocean Service (NOS)          IDB PID#:  BC2545
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   30° 23.7' N (  30.39500)          LONGITUDE:  81° 25.9' W ( -81.43170)


The bench mark is a disk encased in a 4-inch PVC pipe that is flush with the
ground surface, located in Mayport at 4610 Ocean Street, 20.51 m (67.3 ft) ENE
of a flag pole, 16.18 m (53.1 ft) SE of the NE corner of the Ferry Maintenance
Office at 4610 Ocean Street, 9.39 m (30.8 ft) SW of a chain-link fence, and 0.70
m (2.3 ft) NW of the NW corner of a porch along the west side of a warehouse.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  7

                                                                                
Station ID: 8720224                         PUBLICATION DATE:  05/16/2005
Name:       MAYPORT (FERRY DEPOT), ST JOHNS RIVER             
            FL
NOAA Chart: 11490                           Latitude:   30° 23.7' N (  30.39500)
USGS Quad:  MAYPORT                         Longitude:  81° 25.9' W ( -81.43170)


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


                         BENCH MARK STAMPING:  0220 A 1978
                         DESIGNATION:          872 0220 A TIDAL

MONUMENTATION:           Vertical Control disk                 VM#:        13982
AGENCY:                  National Ocean Service (NOS)          IDB PID#:  BC2486
SETTING CLASSIFICATION:  Unspecified deep rod                  OPUS PID:        
LATITUDE:   30° 23.7' N (  30.39500)          LONGITUDE:  81° 25.9' W ( -81.43170)


The bench mark is a disk located on the Ferry Maintenance Facility grounds,
13.32 m (43.7 ft) south of the south corner of an office, 13.11 m (43.0 ft) west
of the west corner of the warehouse, and 2.68 m (8.8 ft) SE of a flagpole.  The
bench mark is crimped to an unspecified steel rod driven to refusal, encased in
a PVC pipe and concrete kickblock.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  7

                                                                                
Station ID: 8720224                         PUBLICATION DATE:  05/16/2005
Name:       MAYPORT (FERRY DEPOT), ST JOHNS RIVER             
            FL
NOAA Chart: 11490                           Latitude:   30° 23.7' N (  30.39500)
USGS Quad:  MAYPORT                         Longitude:  81° 25.9' W ( -81.43170)


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


                         BENCH MARK STAMPING:  EDM 13 1942
                         DESIGNATION:          EDM 13

MONUMENTATION:           Survey disk                           VM#:        13983
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Set into the top of a metal pipe driven
                         into the ground                       OPUS PID:        
LATITUDE:   30° 23.7' N (  30.39500)          LONGITUDE:  81° 25.9' W ( -81.43170)


The bench mark is a disk set atop a pipe on the west side of the warehouse at
the Ferry Maintenance Facility, 5.33 m (17.49 ft) SW of the NW corner of the
warehouse, 1.37 m (4.49 ft) west of its west wall, 0.46 m (1.51 ft) WSW of bench
mark Mayport 2 RM NO 1 1946, and 0.15 m (0.49 ft) south of a concrete slab
inside a wooden fenced area used for garbage can storage.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  6 of  7

                                                                                
Station ID: 8720224                         PUBLICATION DATE:  05/16/2005
Name:       MAYPORT (FERRY DEPOT), ST JOHNS RIVER             
            FL
NOAA Chart: 11490                           Latitude:   30° 23.7' N (  30.39500)
USGS Quad:  MAYPORT                         Longitude:  81° 25.9' W ( -81.43170)


                            T I D A L   D A T U M S 


Tidal datums at MAYPORT (FERRY DEPOT), ST JOHNS RIVER based on:

     LENGTH OF SERIES:      11 MONTHS
     TIME PERIOD:           April 1997 - February 1998
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8720220 MAYPORT


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

     MEAN HIGHER HIGH WATER                     MHHW   =  1.513
     MEAN HIGH WATER                            MHW    =  1.430
     North American Vertical Datum              NAVD88 =  0.939
     MEAN SEA LEVEL                             MSL    =  0.752
     MEAN TIDE LEVEL                            MTL    =  0.737
     MEAN LOW WATER                             MLW    =  0.045
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     BM E.D.M. 15 MSL 1942                       2.679    1.249
     BM E.D.M. 14 M.S.L. 1942                    1.984    0.554
     B 407 1991                                  1.980    0.550
     0220 B 1978                                 2.101    0.671
     0220 A 1978                                 2.205    0.775
     EDM 13 1942                                 2.121    0.691


                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  7 of  7

                                                                                
Station ID: 8720224                         PUBLICATION DATE:  05/16/2005
Name:       MAYPORT (FERRY DEPOT), ST JOHNS RIVER             
            FL
NOAA Chart: 11490                           Latitude:   30° 23.7' N (  30.39500)
USGS Quad:  MAYPORT                         Longitude:  81° 25.9' W ( -81.43170)


                             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.