U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  6

                                                                                
Station ID: 8720168                         PUBLICATION DATE:  11/13/2009
Name:       SIMPSON CREEK                                     
            FL
NOAA Chart: 11488                           Latitude:   30° 27.9' N (  30.46500)
USGS Quad:  MAYPORT                         Longitude:  81° 25.9' W ( -81.43170)


To reach the tidal bench marks from the intersection of State Highway A1A and
105A in Amelia City proceed south on State Highway A1A for 10.5 km (6.5 mi) to
the SW end of the bridge over Sawpit Creek.  The benchmarks are located on the
fifth set of pilings north of the south end of the bridge.    


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


                 PRIMARY BENCH MARK STAMPING:  0168 C 1978
                         DESIGNATION:          872 0168 C TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         5055
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  BC1404
SETTING CLASSIFICATION:  Copper-clad steel rod                 OPUS PID:        
LATITUDE:   30° 27.7' N (  30.46167)          LONGITUDE:  81° 25.6' W ( -81.42694)


The primary bench mark is a disk located 0.5 km (0.3 mi) east of Simpson Creek,
0.2 km (0.1 mi) west of bench mark D 326 1970, 19.8 m (65.0 ft) south of the
intersection of the centerline of State Road A1A (State Road 105) with the
center of the sand driveway into the park, 13.0 m (47.2 ft) SSE of wood power
pole number 30030 30T, 6.3 m (20.7 ft) SW of a large twin pine tree, 5.0 m (16.5
ft) SSW of a cluster of three 10-inch wooden posts at the south side of the park
entrance sign, 4.4 m (14.3 ft) east of the sand driveway, and 0.3 m (1.0 ft)
west of a witness post.  The mark is crimped to the top of a copper-clad steel
rod driven into the ground, and encased in a 4-inch PVC pipe inside a concrete
kickblock projecting 0.1 m (0.4 ft) above ground level.  NOTE:  A magnet was
buried at the south side of the mark.  

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  6

                                                                                
Station ID: 8720168                         PUBLICATION DATE:  11/13/2009
Name:       SIMPSON CREEK                                     
            FL
NOAA Chart: 11488                           Latitude:   30° 27.9' N (  30.46500)
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:  D 326 1970
                         DESIGNATION:          D 326

MONUMENTATION:           Tidal Station disk                    VM#:         5056
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  BC0434
SETTING CLASSIFICATION:  Concrete bridge walkway               OPUS PID:        
LATITUDE:   30° 27.7' N (  30.46111)          LONGITUDE:  81° 25.5' W ( -81.42500)


The bench mark is a disk on the top of the west end of the south bridge walkway
of the Myrtle Creek Bridge (H 1544 1949) on State Road A1A, 0.6 km (0.4 mi) east
of Simpson Creek, 3.9 m (12.7 ft) north of the centerline of the State Road A1A
and 0.3 m (1.0 ft) east of the west end of the walkway.  The mark is a disk set
flush in the top of the concrete bridge walkway and 0.3 m (1.0 ft) above the
level of the State Road A1A (State Road 105).  

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  6

                                                                                
Station ID: 8720168                         PUBLICATION DATE:  11/13/2009
Name:       SIMPSON CREEK                                     
            FL
NOAA Chart: 11488                           Latitude:   30° 27.9' N (  30.46500)
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:  E 326 1970
                         DESIGNATION:          E 326

MONUMENTATION:           Tidal Station disk                    VM#:         5057
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  BC0433
SETTING CLASSIFICATION:  Concrete bridge abutment              OPUS PID:        
LATITUDE:   30° 27.8' N (  30.46333)          LONGITUDE:  81° 26.0' W ( -81.43250)


The bench mark is a disk set flush on top of the west end of the north concrete
walkway of the bridge over Simpson Creek (H 1544 1949) on State Road A1A (State
Road 105), 4.0 m (13.0 ft) north of the centerline of A1A, 0.3 m (1.0 ft) east
of the west end of the walkway, 0.3 m (1.0 ft) above the level of the road.    

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  6

                                                                                
Station ID: 8720168                         PUBLICATION DATE:  11/13/2009
Name:       SIMPSON CREEK                                     
            FL
NOAA Chart: 11488                           Latitude:   30° 27.9' N (  30.46500)
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:  F 326 1970
                         DESIGNATION:          F 326

MONUMENTATION:           Tidal Station disk                    VM#:         5058
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  BC0432
SETTING CLASSIFICATION:  Concrete Bridge Abutment              OPUS PID:        
LATITUDE:   30° 28.0' N (  30.46686)          LONGITUDE:  81° 26.4' W ( -81.43944)


The bench mark is a disk set in a top of a round concrete monument projecting
0.2 m (0.5 ft) above ground level, 13.0 m (42.0 ft) NE of the centerline of
State Road A1A (State Road 105), 9.8 m (32.0 ft) south of Big Pine Trail leading
east, 4.0 m (14.0 ft) west of a large twin trunked oak tree, 0.5 m (1.5 ft)
north of a metal witness post and 0.2 m (0.5 ft) west of a carsonite witness
post.  NOTE:  A magnet was buried at the south side of the mark.  



                         BENCH MARK STAMPING:  0168 D 2004
                         DESIGNATION:          872 0168 D TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:        19265
AGENCY:                  FL Dept. of Environmental Protection
                         (FLDEP)                               IDB PID#:  DH8955
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   30° 27.8' N (  30.46389)          LONGITUDE:  81° 26.0' W ( -81.43350)


The bench mark is a disk located 14.8 m (48.6 ft) SW of the centerline of State
Road A1A (State Road 105), 2.0 m (6.5 ft) south of a 7-inch wooden corner post
for a 1.2 m (4.0 ft) high hogwire fence, 0.5 m (1.8 ft) SE of the hogwire fence
and 0.2 m (0.5 ft) SE of a carsonite witness post.  The datum point is recessed
0.1 m (0.2 ft) below the level of the NGS logo cap, being crimped to the top of
a stainless steel rod driven to refusal at a depth of 14.8 m (48.5 ft) with a
5-inch NGS logo cap flush with the ground and about 0.3 m (1.0 ft) below the
level of State Road A1A (State Road 105).  NOTE:  A magnet was buried at the
south side of the mark.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  6

                                                                                
Station ID: 8720168                         PUBLICATION DATE:  11/13/2009
Name:       SIMPSON CREEK                                     
            FL
NOAA Chart: 11488                           Latitude:   30° 27.9' N (  30.46500)
USGS Quad:  MAYPORT                         Longitude:  81° 25.9' W ( -81.43170)


                            T I D A L   D A T U M S 


Tidal datums at SIMPSON CREEK based on:

     LENGTH OF SERIES:      5 MONTHS
     TIME PERIOD:           April 1978 - August 1978
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8720220 MAYPORT (FERRY DEPOT), SAINT JOHNS RIVER


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

     MEAN HIGHER HIGH WATER                     MHHW   =  1.691
     MEAN HIGH WATER                            MHW    =  1.586
     North American Vertical Datum              NAVD88 =  0.968
     MEAN SEA LEVEL                             MSL    =  0.829
     MEAN TIDE LEVEL                            MTL    =  0.812
     MEAN LOW WATER                             MLW    =  0.038
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     0168 C 1978                                 3.090    1.504
     D 326 1970                                  4.383    2.797
     E 326 1970                                  5.162    3.576
     F 326 1970                                  4.842    3.256
     0168 D 2004                                 4.370    2.784


Foot Notes:

Geodetic heights of the bench marks meet all NOAA/NOS/NGS quality control
standards for Second Order, Class 1 leveling.  It is advised that a confirmation
set of levels be established for bench mark 0168 D 2004 to verify height
differences before using tidal bench mark elevation information.

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

                                                                                
Station ID: 8720168                         PUBLICATION DATE:  11/13/2009
Name:       SIMPSON CREEK                                     
            FL
NOAA Chart: 11488                           Latitude:   30° 27.9' N (  30.46500)
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.