U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  8

                                                                                
Station ID: 8726604                         PUBLICATION DATE:  04/01/2004
Name:       LONG SHOAL, MACDILL AFB                           
            FL
NOAA Chart: 11412                           Latitude:   27° 51.3' N (  27.85500)
USGS Quad:  GIBSONTON                       Longitude:  82° 28.8' W ( -82.48000)


To reach the tidal bench marks from the Bayshore Drive Gate at MacDill Air Force
Base, proceed 1.3 km (0.8 mi) south on Bayshore Drive.  The bench marks are
located along Bayshore Drive.  The tide gage and staff were located on the
southernmost wharf at the Air Force Base.


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


                 PRIMARY BENCH MARK STAMPING:  NO 1 1975
                         DESIGNATION:          872 6604 TIDAL 1

MONUMENTATION:           Tidal Station disk                    VM#:         6608
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AG7532
SETTING CLASSIFICATION:  Concrete pad                          OPUS PID:        
LATITUDE:   27° 51.3' N (  27.85500)          LONGITUDE:  82° 28.4' W ( -82.47330)


The primary bench mark is a disk set flush in the NW corner of a concrete pad
located on the NW end of the NOC Annex Building 349, 48 m (158 ft) NE of the
bench mark NO 2 1975, 11 m (35 ft) west of the west edge of the dock, 6.83 m
(22.4 ft) NW of the NE corner of building 353, 2 m (7 ft) NE of the NW corner of
building 349, and 0.3 m (1 ft) above ground level.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  8

                                                                                
Station ID: 8726604                         PUBLICATION DATE:  04/01/2004
Name:       LONG SHOAL, MACDILL AFB                           
            FL
NOAA Chart: 11412                           Latitude:   27° 51.3' N (  27.85500)
USGS Quad:  GIBSONTON                       Longitude:  82° 28.8' W ( -82.48000)


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


                         BENCH MARK STAMPING:  NO 2 1975
                         DESIGNATION:          872 6604 TIDAL 2

MONUMENTATION:           Tidal Station disk                    VM#:         6609
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AG7533
SETTING CLASSIFICATION:  Copper-clad steel rod                 OPUS PID:        
LATITUDE:   27° 51.3' N (  27.85500)          LONGITUDE:  82° 28.9' W ( -82.48170)


The bench mark is a disk located near the docks and building #353, 53 m (173 ft)
west of the west edge of dock, 48 m (158 ft) SW of bench mark NO 1 1975, 48 m
(158 ft) west of bench mark MDF-46 1952, 19.0 m (62.5 ft) east of the centerline
of Bayshore Drive, and 1 m (2 ft) north of utility pole #1-29A1.  The bench mark
is crimped to the top of a copper-clad steel rod driven 14.6 m (48 ft) to
refusal, encased in a PVC pipe and a concrete kickblock.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  8

                                                                                
Station ID: 8726604                         PUBLICATION DATE:  04/01/2004
Name:       LONG SHOAL, MACDILL AFB                           
            FL
NOAA Chart: 11412                           Latitude:   27° 51.3' N (  27.85500)
USGS Quad:  GIBSONTON                       Longitude:  82° 28.8' W ( -82.48000)


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


                         BENCH MARK STAMPING:  MDF-46 1952
                         DESIGNATION:          MDF 46 USE

MONUMENTATION:           Bench Mark disk                       VM#:         6610
AGENCY:                  US Army Corps of Engineers (USE)      IDB PID#:  AG7534
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID:        
LATITUDE:   27° 51.3' N (  27.85500)          LONGITUDE:  82° 28.9' W ( -82.48170)


The bench mark is a disk set flush in a concrete monument, 48 m (158 ft) east of
bench mark NO 2 1975, 16 m (51 ft) SE of the SW corner of building #349, 12.41 m
(40.7 ft) SE of the SE corner of building #353, and 5 m (15 ft) west of the west
edge of the docks.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  8

                                                                                
Station ID: 8726604                         PUBLICATION DATE:  04/01/2004
Name:       LONG SHOAL, MACDILL AFB                           
            FL
NOAA Chart: 11412                           Latitude:   27° 51.3' N (  27.85500)
USGS Quad:  GIBSONTON                       Longitude:  82° 28.8' W ( -82.48000)


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


                         BENCH MARK STAMPING:  MDF 97 JAX 1966
                         DESIGNATION:          MDF 97 USE

MONUMENTATION:           Bench Mark disk                       VM#:         6611
AGENCY:                  US Army Corps of Engineers (USE)      IDB PID#:  AG7531
SETTING CLASSIFICATION:  Concrete pavement                     OPUS PID:        
LATITUDE:   27° 51.3' N (  27.85500)          LONGITUDE:  82° 29.2' W ( -82.48670)


The bench mark is a disk set flush in a concrete road, 67 m (221 ft) NNE of the
NW corner of Building 501 Readiness Command Headquarters), 25 m (83 ft) SW of a
flagpole, and 6.80 m (22.3 ft) west of the east curb of Tampa Boulevard.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  8

                                                                                
Station ID: 8726604                         PUBLICATION DATE:  04/01/2004
Name:       LONG SHOAL, MACDILL AFB                           
            FL
NOAA Chart: 11412                           Latitude:   27° 51.3' N (  27.85500)
USGS Quad:  GIBSONTON                       Longitude:  82° 28.8' W ( -82.48000)


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


                         BENCH MARK STAMPING:  MDF 101 1967
                         DESIGNATION:          MDF 101 USE

MONUMENTATION:           Bench Mark disk                       VM#:         6612
AGENCY:                  US Army Corps of Engineers (USE)      IDB PID#:        
SETTING CLASSIFICATION:  Concrete pad                          OPUS PID:        
LATITUDE:   27° 51.3' N (  27.85500)          LONGITUDE:  82° 28.8' W ( -82.48000)


The bench mark is a disk set in a concrete pad located in a grassy park area
near a flagpole, 22 m (72 ft) north of bench mark MDF 97 JAX 1966, and 13.90 m
(45.6 ft) WNW of the flagpole.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  6 of  8

                                                                                
Station ID: 8726604                         PUBLICATION DATE:  04/01/2004
Name:       LONG SHOAL, MACDILL AFB                           
            FL
NOAA Chart: 11412                           Latitude:   27° 51.3' N (  27.85500)
USGS Quad:  GIBSONTON                       Longitude:  82° 28.8' W ( -82.48000)


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


                         BENCH MARK STAMPING:  H 262 1966
                         DESIGNATION:          H 262

MONUMENTATION:           Bench Mark disk                       VM#:        17211
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AG6112
SETTING CLASSIFICATION:  Concrete foundation                   OPUS PID:        
LATITUDE:   27° 51.0' N (  27.85000)          LONGITUDE:  82° 29.5' W ( -82.49170)


The bench mark is a disk set vertically in the SW face near the south corner of
the concrete foundation to the offset of the SE side of hangar #5, 0.4 m (1.4
ft) NW of the south corner of the foundation, 0.3 m (1.1 ft) above the sidewalk,
and 1 m (2 ft) above the level of the parking ramp.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  7 of  8

                                                                                
Station ID: 8726604                         PUBLICATION DATE:  04/01/2004
Name:       LONG SHOAL, MACDILL AFB                           
            FL
NOAA Chart: 11412                           Latitude:   27° 51.3' N (  27.85500)
USGS Quad:  GIBSONTON                       Longitude:  82° 28.8' W ( -82.48000)


                            T I D A L   D A T U M S 


Tidal datums at LONG SHOAL, MACDILL AFB based on:

     LENGTH OF SERIES:      1 MONTH
     TIME PERIOD:           December 1975 - December 1975
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8726520 ST. PETERSBURG, TAMPA BAY


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

     MEAN HIGHER HIGH WATER                     MHHW   =  0.786
     MEAN HIGH WATER                            MHW    =  0.720
     North American Vertical Datum              NAVD88 =  0.492
     MEAN SEA LEVEL                             MSL    =  0.436
     MEAN TIDE LEVEL                            MTL    =  0.418
     MEAN LOW WATER                             MLW    =  0.116
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     NO 1 1975                                   1.928    1.208
     NO 2 1975                                   1.901    1.181
     MDF-46 1952                                 1.923    1.203
     MDF 97 JAX 1966                             2.864    2.144
     MDF 101 1967                                2.916    2.196
     H 262 1966                                  3.256    2.536


                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  8 of  8

                                                                                
Station ID: 8726604                         PUBLICATION DATE:  04/01/2004
Name:       LONG SHOAL, MACDILL AFB                           
            FL
NOAA Chart: 11412                           Latitude:   27° 51.3' N (  27.85500)
USGS Quad:  GIBSONTON                       Longitude:  82° 28.8' W ( -82.48000)


                             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.