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

                                                                                
Station ID: 8726614                         PUBLICATION DATE:  05/12/2004
Name:       ALAFIA RIVER NORTH                                
            FL
NOAA Chart: 11412                           Latitude:   27° 52.2' N (  27.87000)
USGS Quad:  BRANDON                         Longitude:  82° 19.7' W ( -82.32830)


To reach the tidal bench marks from the intersection of Riverview Drive and U.S.
Highway 301 in Riverview, proceed south on U.S. Highway 301 to Glen D. Litkes
Auto Salvage Company.  The bench marks are located near the Salvage Company. 
The tide gage and staff were located on the wooden dock behind the Salvage
Company.


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


                 PRIMARY BENCH MARK STAMPING:  6614 A 1977
                         DESIGNATION:          872 6614 A TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         6623
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AG7481
SETTING CLASSIFICATION:  Concrete bridge abutment              OPUS PID:        
LATITUDE:   27° 52.2' N (  27.87000)          LONGITUDE:  82° 19.6' W ( -82.32670)


The primary bench mark is a disk at the NE corner of the bridge over the Alafia
River, 8.05 m (26.4 ft) east of the centerline of U.S. Highway 301, 2 m (6 ft)
east of the east edge of the bridge, and 0.43 m (1.4 ft) west of the west edge
of the abutment foundation.



                         BENCH MARK STAMPING:  6614 B 1977
                         DESIGNATION:          872 6614 B TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         6624
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AG7480
SETTING CLASSIFICATION:  Concrete bridge abutment wing wall    OPUS PID:        
LATITUDE:   27° 52.2' N (  27.87000)          LONGITUDE:  82° 19.6' W ( -82.32670)


The bench mark is a disk set in the concrete abutment wing wall at the NW corner
of the bridge over the Alafia River,  6.55 m (21.5 ft) west of the centerline of
U.S. Highway 301, 2 m (6 ft) east of the west end of the bridge abutment wing
wall, and 0.21 m (0.7 ft) west of the bridge rail.

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

                                                                                
Station ID: 8726614                         PUBLICATION DATE:  05/12/2004
Name:       ALAFIA RIVER NORTH                                
            FL
NOAA Chart: 11412                           Latitude:   27° 52.2' N (  27.87000)
USGS Quad:  BRANDON                         Longitude:  82° 19.7' W ( -82.32830)


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


                         BENCH MARK STAMPING:  6614 C 1977
                         DESIGNATION:          872 6614 C TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         6625
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AG7482
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID:        
LATITUDE:   27° 52.2' N (  27.87000)          LONGITUDE:  82° 19.5' W ( -82.32500)


The bench mark is a disk set in the top of a concrete monument, NE of the north
end of the bridge over the Alafia River, on the property of the Glen Litke Auto
Salvage Company, 18.75 m (61.5 ft) NE of the SE corner of a wood frame house,
14.26 m (46.8 ft) west of a fence, 14 m (45 ft) north of north river bank, 12.65
m (41.5 ft) NNE of the north end of a wooden walkway to a dock, 0.52 m (1.7 ft)
south of the SE corner of a tin building, and 0.40 m (1.3 ft) south of a witness
post.



                         BENCH MARK STAMPING:  6614 E 1977
                         DESIGNATION:          872 6614 E TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         6626
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AG7479
SETTING CLASSIFICATION:  Concrete curb drain                   OPUS PID:        
LATITUDE:   27° 52.3' N (  27.87170)          LONGITUDE:  82° 19.6' W ( -82.32670)


The bench mark is a disk set in top of a concrete store drain in front of the
property for the Auto Salvage Company, 12.25 m (40.2 ft) SW of the SW corner of
a bike parts supply building, 11 m (37 ft) SW of a powerline pole, and 8.17 m
(26.8 ft) east of the centerline of U.S. Highway 301.

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

                                                                                
Station ID: 8726614                         PUBLICATION DATE:  05/12/2004
Name:       ALAFIA RIVER NORTH                                
            FL
NOAA Chart: 11412                           Latitude:   27° 52.2' N (  27.87000)
USGS Quad:  BRANDON                         Longitude:  82° 19.7' W ( -82.32830)


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


                         BENCH MARK STAMPING:  6614 F 1977
                         DESIGNATION:          872 6614 F TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         6627
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AG7478
SETTING CLASSIFICATION:  Concrete curb drain                   OPUS PID:        
LATITUDE:   27° 52.3' N (  27.87170)          LONGITUDE:  82° 19.6' W ( -82.32670)


The bench mark is a disk set in the top of a concrete storm drain at the NE
corner of the intersection of U.S. Highway 301 and Riverview Drive, 12 m (41 ft)
north of the centerline of Riverview Drive, 9.78 m (32.1 ft) east of the
centerline of U.S. Highway 301, 7.19 m (23.6 ft) west of a telephone pole, and 3
m (9 ft) WSW of traffic light pole # 0735.

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

                                                                                
Station ID: 8726614                         PUBLICATION DATE:  05/12/2004
Name:       ALAFIA RIVER NORTH                                
            FL
NOAA Chart: 11412                           Latitude:   27° 52.2' N (  27.87000)
USGS Quad:  BRANDON                         Longitude:  82° 19.7' W ( -82.32830)


                            T I D A L   D A T U M S 


Tidal datums at ALAFIA RIVER NORTH based on:

     LENGTH OF SERIES:      2 MONTHS
     TIME PERIOD:           March 1977 - April 1977
     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   =  0.867
     MEAN HIGH WATER                            MHW    =  0.774
     North American Vertical Datum              NAVD88 =  0.519
     MEAN SEA LEVEL                             MSL    =  0.465
     MEAN TIDE LEVEL                            MTL    =  0.454
     MEAN LOW WATER                             MLW    =  0.134
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     6614 A 1977                                 4.567    3.793
     6614 B 1977                                 6.104    5.330
     6614 C 1977                                 2.093    1.319
     6614 E 1977                                 4.347    3.573
     6614 F 1977                                 5.026    4.252


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

                                                                                
Station ID: 8726614                         PUBLICATION DATE:  05/12/2004
Name:       ALAFIA RIVER NORTH                                
            FL
NOAA Chart: 11412                           Latitude:   27° 52.2' N (  27.87000)
USGS Quad:  BRANDON                         Longitude:  82° 19.7' W ( -82.32830)


                             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.