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

                                                                                
Station ID: 8720211                         PUBLICATION DATE:  08/25/2011
Name:       WWTD, MAYPORT NAVAL STA., ST JOHNS RIVER          
            FL
NOAA Chart: 11490                           Latitude:   30° 24.0' N (  30.40000)
USGS Quad:  MAYPORT                         Longitude:  81° 24.8' W ( -81.41330)


To reach the tidal bench marks from the overpass of Atlantic Boulevard (State
Road 10) over Mayport Road (State Road A1A), proceed north along Mayport Road
(SR A1A) for 3.6 km (2.3 mi) to a fork in the road, State Road A1A bears left
(NW) while continuing straight ahead (North) on the same street (now called
State Road 101, Main Street) for 2.9 km (1.8 mi) to the main gate of the navy
base.  A pass is required for admittance to the base, this may be obtained from
an office just south of the main gate and east of Main Street.  After passing
through the gate, go north on Main Street for 2.1 km (1.3 mi) to the hazardous
waste storage area.  The tide gage is installed on the north end of the waste
water treatment dock, located about 100.6 m (330.0 ft) north of the NW corner of
Building Number 1241, about 48.2 m (158.0 ft) north of the south end of the
waste water treatment dock and 43.3 m (141.9 ft) north of bench mark 0211 C
1995.  Note:  This is a temporary Aqua Trak (tide gage) which is subject to
being removed.  


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


                 PRIMARY BENCH MARK STAMPING:  0211 A 1995
                         DESIGNATION:          872 0211 A TIDAL

MONUMENTATION:           Flange-encased Rod                    VM#:        13465
AGENCY:                  National Ocean Service (NOS)          IDB PID#:  DI9219
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID#: DI9219
LATITUDE:   30° 24.0' N (  30.39944)          LONGITUDE:  81° 24.8' W ( -81.41278)


The primary bench mark is a flange-encased rod located 69.5 m (228.0 ft) NE of
0211 A 1995, 30.1 m (98.8 ft) SE of a 61.0 cm (24.0 in) palm tree, 18.4 m (60.5
ft) NE of the NE edge of the parking lot and 0.6 m (1.9 ft) west of the NW
corner of a 1.8 m (6.0 ft) tall chainlink fence line.  The datum point is
recessed 0.1 m (0.3 ft) below the level of the NOS logo cap, being the top of a
stainless steel rod, driven to refusal at a depth of 24.3 m (79.8 ft), and
encased in a 5-inch NGS logo cap flush with the ground.  

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

                                                                                
Station ID: 8720211                         PUBLICATION DATE:  08/25/2011
Name:       WWTD, MAYPORT NAVAL STA., ST JOHNS RIVER          
            FL
NOAA Chart: 11490                           Latitude:   30° 24.0' N (  30.40000)
USGS Quad:  MAYPORT                         Longitude:  81° 24.8' W ( -81.41330)


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


                         BENCH MARK STAMPING:  0211 B 1995
                         DESIGNATION:          872 0211 B

MONUMENTATION:           Flange-encased Rod                    VM#:        13466
AGENCY:                  National Ocean Service (NOS)          IDB PID#:  DL5745
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID#: DL5745
LATITUDE:   30° 24.0' N (  30.39972)          LONGITUDE:  81° 24.9' W ( -81.41500)


The bench mark is a flange-encased rod located 51.4 m (168.5 ft) NE of the
approximate center of a paved road, 45.5 m (149.3 ft) NE of the SW end of a
chainlink fence line, 41.0 m (134.6 ft) SSE of a palm tree, 7.1 m (23.3 ft) SW
of the NE end of a chainlink fence line and 0.3 m (1.0 ft) SE of a NE-SW
chainlink fence line and a carsonite witness post.  The datum point is recessed
0.1 m (0.3 ft) below the level of the NOS logo cap, being the top of a stainless
steel rod, driven to refusal at a depth of 21.8 m (71.4 ft), and encased in a
5-inch NGS logo cap flush with the ground.



                         BENCH MARK STAMPING:  0211 C 1995
                         DESIGNATION:          872 0211 C

MONUMENTATION:           Tidal Station disk                    VM#:        13467
AGENCY:                  National Ocean Service (NOS)          IDB PID#:  DL5785
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID:        
LATITUDE:   30° 24.0' N (  30.39917)          LONGITUDE:  81° 24.7' W ( -81.41167)


The bench mark is a disk set flush in the south end of the small concrete waste
water treatment pier, 28.0 m (92.0 ft) north of the NE corner of the waste
treatment building, 5.0 m (16.5 ft) north of the south end of the waste
treatment dock (a 0.9 m (3.0 ft) wide dock) and 4.3 m (14.2 ft) SW of the south
end of a north-south 1.8 m (6.0 ft) tall chainlink fence line.  

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

                                                                                
Station ID: 8720211                         PUBLICATION DATE:  08/25/2011
Name:       WWTD, MAYPORT NAVAL STA., ST JOHNS RIVER          
            FL
NOAA Chart: 11490                           Latitude:   30° 24.0' N (  30.40000)
USGS Quad:  MAYPORT                         Longitude:  81° 24.8' W ( -81.41330)


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


                         BENCH MARK STAMPING:  K 324 1970
                         DESIGNATION:          K 324

MONUMENTATION:           Bench Mark disk                       VM#:        13468
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  BC0464
SETTING CLASSIFICATION:  Concrete Base                         OPUS PID:        
LATITUDE:   30° 23.9' N (  30.39833)          LONGITUDE:  81° 24.9' W ( -81.41472)


The bench mark is a disk set flush in the top of the NW corner of the concrete
base supporting a large steel bollard, 17.4 m (57.0 ft) SW of the NW corner of
the basin, 6.2 m (20.2 ft) west of the west edge of the bulkhead, and 0.9 m (3.0
ft) NW of a large steel bollard.    

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

                                                                                
Station ID: 8720211                         PUBLICATION DATE:  08/25/2011
Name:       WWTD, MAYPORT NAVAL STA., ST JOHNS RIVER          
            FL
NOAA Chart: 11490                           Latitude:   30° 24.0' N (  30.40000)
USGS Quad:  MAYPORT                         Longitude:  81° 24.8' W ( -81.41330)


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


                         BENCH MARK STAMPING:  TUG 1989 JAX. FL.
                         DESIGNATION:          TUG

MONUMENTATION:           Bench Mark disk                       VM#:        13469
AGENCY:                  US Army Corps of Engineers (USE)      IDB PID#:  DL5780
SETTING CLASSIFICATION:  Concrete Base                         OPUS PID:        
LATITUDE:   30° 23.9' N (  30.39833)          LONGITUDE:  81° 24.8' W ( -81.41361)


The bench mark is a disk set flush on the top of the NE corner of the concrete
base supporting a large steel bollard, 27.4 m (90.0 ft) south of the approximate
center of main street, 4.5 m (14.6 ft) south of the SE corner of a small
building, and 1.3 m (4.3 ft) north of survey mark MP 7 1979.    

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

                                                                                
Station ID: 8720211                         PUBLICATION DATE:  08/25/2011
Name:       WWTD, MAYPORT NAVAL STA., ST JOHNS RIVER          
            FL
NOAA Chart: 11490                           Latitude:   30° 24.0' N (  30.40000)
USGS Quad:  MAYPORT                         Longitude:  81° 24.8' W ( -81.41330)


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


                         BENCH MARK STAMPING:  MP-7 1979 DET 4 GSS
                         DESIGNATION:          MP 7

MONUMENTATION:           Bench Mark disk                       VM#:        13470
AGENCY:                  US Army Corps of Engineers (USE)      IDB PID#:  DL5781
SETTING CLASSIFICATION:  Concrete Base                         OPUS PID:        
LATITUDE:   30° 23.9' N (  30.39861)          LONGITUDE:  81° 24.8' W ( -81.41389)


The bench mark is a disk set flush in the top of the NE corner of the concrete
base supporting a large steel bollard, 27.4 m (90.0 ft) south of the approximate
center of Main Street, 4.5 m (14.6 ft) south of the SE corner of a small
building and 1.3 m (4.3 ft) north of survey mark TUG 1980.      

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

                                                                                
Station ID: 8720211                         PUBLICATION DATE:  08/25/2011
Name:       WWTD, MAYPORT NAVAL STA., ST JOHNS RIVER          
            FL
NOAA Chart: 11490                           Latitude:   30° 24.0' N (  30.40000)
USGS Quad:  MAYPORT                         Longitude:  81° 24.8' W ( -81.41330)


                            T I D A L   D A T U M S 


Tidal datums at WWTD, MAYPORT NAVAL STA., ST JOHNS RIVER based on:

     LENGTH OF SERIES:      1 YEAR
     TIME PERIOD:           November 2003 - October 2004
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8720218 BAR PILOTS DOCK, ST JOHNS RIVER


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

     HIGHEST OBSERVED WATER LEVEL (09/27/2004)         =  2.382
     MEAN HIGHER HIGH WATER                     MHHW   =  1.559
     MEAN HIGH WATER                            MHW    =  1.469
     North American Vertical Datum              NAVD88 =  0.947
     MEAN SEA LEVEL                             MSL    =  0.774
     MEAN TIDE LEVEL                            MTL    =  0.759
     MEAN LOW WATER                             MLW    =  0.047
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (03/08/2005)         = -0.569

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     0211 A 1995                                 3.634    2.165
     0211 B 1995                                 3.259    1.790
     0211 C 1995                                 3.261    1.792
     K 324 1970                                  3.471    2.002
     TUG 1989 JAX. FL.                           3.691    2.222
     MP-7 1979 DET 4 GSS                         3.671    2.202


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

                                                                                
Station ID: 8720211                         PUBLICATION DATE:  08/25/2011
Name:       WWTD, MAYPORT NAVAL STA., ST JOHNS RIVER          
            FL
NOAA Chart: 11490                           Latitude:   30° 24.0' N (  30.40000)
USGS Quad:  MAYPORT                         Longitude:  81° 24.8' W ( -81.41330)


                             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.