Bench Mark Sheet for 8720220, Mayport (Ferry Depot) FL

Superseded Epoch

Large map location marker Station Location
Small red map location marker Published bench mark
Small blue map location marker Unpublished bench mark

Bench mark positions only appear on the map if their coordinates in the CO-OPS database are at the precision of degrees/minutes/seconds/and tenths of seconds. If the coordinates are less precise, the mark will not appear.

Printable version

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of 12

                                                                                
Station ID: 8720220                         PUBLICATION DATE:  11/16/2009
Name:       MAYPORT (FERRY DEPOT), SAINT JOHNS RIVER          
            FL
NOAA Chart: 11490                           Latitude:   30° 23.6' N (  30.39330)
USGS Quad:  MAYPORT                         Longitude:  81° 25.9' W ( -81.43170)


To reach the tidal bench marks from the St Johns River Ferry landing at the
intersection of Broad and Ocean Streets in Mayport, proceed SW on Ocean Street
for 0.3 km (0.2 mi) to the Florida Department of Transportation on Ferry
Maintenance facility.  The bench marks are on the ferry maintenance facility
grounds and along Palmer Avenue.  The tide gage and staff are located on the 
north corner of the ferry maintenance pier.  


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


                 PRIMARY BENCH MARK STAMPING:  BM EDM 15 MSL 1942
                         DESIGNATION:          EDM 15

MONUMENTATION:           Survey disk                           VM#:          650
AGENCY:                  US Army Corps of Engineers (USE)      IDB PID#:  BC0458
SETTING CLASSIFICATION:  Concrete step                         OPUS PID:        
LATITUDE:   30° 23.6' N (  30.39278)          LONGITUDE:  81° 25.7' W ( -81.42917)


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 (4610 Ocean Street),
located 57.3 m (188.0 ft) SE of the SE corner of the ferry maintenance office,
23.3 m (76.4 ft) SW of the center of an entrance road and gate, and 14.0 m (45.9
ft) NW of the center of Ocean Street.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of 12

                                                                                
Station ID: 8720220                         PUBLICATION DATE:  11/16/2009
Name:       MAYPORT (FERRY DEPOT), SAINT JOHNS RIVER          
            FL
NOAA Chart: 11490                           Latitude:   30° 23.6' N (  30.39330)
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:  12 7.861
                         DESIGNATION:          872 0220 TIDAL 12

MONUMENTATION:           Tidal Station disk                    VM#:          652
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  BC0461
SETTING CLASSIFICATION:  Concrete retaining wall               OPUS PID:        
LATITUDE:   30° 23.7' N (  30.39444)          LONGITUDE:  81° 25.8' W ( -81.42944)


The bench mark is a disk set in a concrete retaining wall along the NE side of
Palmer Street, located near the intersection of Palmer and Ocean Streets, 28.9 m
(94.8 ft) SE of the centerline of Ocean Street, 17.5 m (57.4 ft) east of Utility
Pole No. 20, 6.6 m (21.7 ft) NW of the SE end of the retaining wall, 5.6 m (18.4
ft) NE of the centerline of Palmer Street, 5.8 m (19.0 ft) SSW of Utility Pole
No. 146, 0.2 m (0.7 ft) SW of a witness post, and 0.49 m (1.6 ft) above the
level of Palmer Street.



                         BENCH MARK STAMPING:  13 8.022
                         DESIGNATION:          872 0220 TIDAL 13

MONUMENTATION:           Tidal Station disk                    VM#:          653
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  BC0462
SETTING CLASSIFICATION:  Concrete step                         OPUS PID:        
LATITUDE:   30° 23.6' N (  30.39333)          LONGITUDE:  81° 25.7' W ( -81.42778)


The bench mark is a disk set in a concrete step at 1347 Palmer Street, located
near the NW end of the bottom step at the main entrance to the Marine Science
Education Center School No. 32 on Palmer Street, 15.2 m (49.9 ft) SSE of the NW
corner of the building, 10.4 m (34.1 ft) NE of the centerline of Palmer Street,
and 6.1 m (20 ft) ESE of a flag pole.  

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of 12

                                                                                
Station ID: 8720220                         PUBLICATION DATE:  11/16/2009
Name:       MAYPORT (FERRY DEPOT), SAINT JOHNS RIVER          
            FL
NOAA Chart: 11490                           Latitude:   30° 23.6' N (  30.39330)
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 MSL
                         DESIGNATION:          EDM 13

MONUMENTATION:           Survey disk                           VM#:          654
AGENCY:                  US Army Corps of Engineers (USE)      IDB PID#:        
SETTING CLASSIFICATION:  Pipe mark                             OPUS PID:        
LATITUDE:   30° 23.5' N (  30.39170)          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 (17.5 ft) SW of the NW corner of the
warehouse, 1.37 m (4.5 ft) west of its west wall, 0.46 m (1.5 ft) WSW of bench
mark MAYPORT 2 RM NO 1 1946, and 0.15 m (0.5 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  4 of 12

                                                                                
Station ID: 8720220                         PUBLICATION DATE:  11/16/2009
Name:       MAYPORT (FERRY DEPOT), SAINT JOHNS RIVER          
            FL
NOAA Chart: 11490                           Latitude:   30° 23.6' N (  30.39330)
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 EDM 14 1942 MSL
                         DESIGNATION:          EDM 14

MONUMENTATION:           Tidal Station disk                    VM#:          655
AGENCY:                  US Army Corps of Engineers (USE)      IDB PID#:  BC0467
SETTING CLASSIFICATION:  Concrete block                        OPUS PID:        
LATITUDE:   30° 23.6' N (  30.39333)          LONGITUDE:  81° 25.7' W ( -81.42889)


The bench mark is a disk set in the top of a concrete block near a garage at the
Ferry Maintenance Facility, located 20.8 m (68.2 ft) SW of the SE corner of the
office building, 17.8 m (58.4 ft) WSW of a flag pole, 3.2 m (10.5 ft) NNW of the
NW corner of a garage, 0.5 m (1.6 ft) NE of a witness post, and 0.1 m (0.3 ft)
below ground level.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of 12

                                                                                
Station ID: 8720220                         PUBLICATION DATE:  11/16/2009
Name:       MAYPORT (FERRY DEPOT), SAINT JOHNS RIVER          
            FL
NOAA Chart: 11490                           Latitude:   30° 23.6' N (  30.39330)
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:  MAYPORT 2 RM. NO 1 1946
                         DESIGNATION:          MAYPORT 2 RM 1

MONUMENTATION:           Tidal Station disk                    VM#:          656
AGENCY:                  US Army Corps of Engineers (USE)      IDB PID#:  BC0459
SETTING CLASSIFICATION:  Tierra cotta pipe                     OPUS PID:        
LATITUDE:   30° 23.5' N (  30.39222)          LONGITUDE:  81° 25.8' W ( -81.42972)


The bench mark is a disk set in a 4-inch concrete filled pipe, located near a
warehouse at the Ferry Maintenance Facility, 21.6 m (70.9 ft) ESE of the SE
corner of the ferry maintenance office, 16.0 m (52.5 ft) east of a flag pole,
2.4 m (7.9 ft) SSE of the SW corner of a warehouse, 0.4 m (1.3 ft) SE of the NE
corner of a 1.0 m x 2.0 m (3.0 ft x 7.0 ft) concrete block, and 0.1 m (0.4 ft)
above ground level.    



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

MONUMENTATION:           Tidal Station disk                    VM#:          657
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  BC2486
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID#: BC2486
LATITUDE:   30° 23.6' N (  30.39333)          LONGITUDE:  81° 25.9' W ( -81.43139)


The bench mark is a disk, located at the Ferry Maintenance Facility at 4610
Ocean Street, 17.4 m (57.1 ft) NE of the NE corner of a garage, 11.5 m (37.7 ft)
SE of the SE corner of the ferry maintenance office, 13.0 m (43.0 ft) west of
the west corner of the warehouse, and 2.7 m (8.9 ft) SE of a flagpole.  The
bench mark is crimped to a stainless steel rod, driven an unspecified depth to
refusal, and encased in a 4-inch PVC pipe that is flush with the ground surface.
 

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  6 of 12

                                                                                
Station ID: 8720220                         PUBLICATION DATE:  11/16/2009
Name:       MAYPORT (FERRY DEPOT), SAINT JOHNS RIVER          
            FL
NOAA Chart: 11490                           Latitude:   30° 23.6' N (  30.39330)
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 B 1978
                         DESIGNATION:          872 0220 B TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:          658
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  BC2545
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   30° 23.6' N (  30.39361)          LONGITUDE:  81° 25.9' W ( -81.43111)


The bench mark is a disk located near a warehouse at the Ferry Maintenance
Facility, 20.5 m (67.3 ft) ENE of a flag pole, 16.2 m (53.1 ft) SE of the NE
corner of the office, 9.4 m (30.8 ft) SW of a chain-link fence, and 0.7 m (2.3
ft) NW of the NW corner of a porch along the west side of a warehouse.  The
bench mark is crimped to a stainless steel rod driven an unspecified depth to
refusal, and encased in a 4-inch PVC pipe that is flush with ground level.



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

MONUMENTATION:           Tidal Station disk                    VM#:          659
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  BC2544
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   30° 23.7' N (  30.39444)          LONGITUDE:  81° 25.8' W ( -81.42944)


The bench mark is a disk located at the intersection of Ocean and Palmer
Streets, 50.2 m (164.7 ft) SE of the centerline of Ocean Street, 21.0 m (68.9
ft) NW of the SW corner of a chain-link fence, 14.0 m (45.9 ft) NE of the bottom
step of a house at 1456 Palmer Street, 12.0 m (39.4 ft) north of utility light
pole No. 1450 with a transformer, and 4.8 m (15.7 ft) NE of and level with the
center of Palmer Street.  The bench mark is crimped to a stainless steel rod
driven, an unspecified depth to refusal, and encased in a 4-inch PVC pipe and
concrete kickblock.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  7 of 12

                                                                                
Station ID: 8720220                         PUBLICATION DATE:  11/16/2009
Name:       MAYPORT (FERRY DEPOT), SAINT JOHNS RIVER          
            FL
NOAA Chart: 11490                           Latitude:   30° 23.6' N (  30.39330)
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:   
                         DESIGNATION:          872 0220 TIDAL 9
                         ALIAS:                9

MONUMENTATION:           Pipe Cap                              VM#:          660
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  BC0466
SETTING CLASSIFICATION:  Iron pipe                             OPUS PID:        
LATITUDE:   30° 23.5' N (  30.39170)          LONGITUDE:  81° 25.9' W ( -81.43170)


The bench mark is a an iron cap located on the Ferry Maintenance Facility
grounds, 14 m (46 ft) west of the centerline of Ocean Street, 10.36 m (34.0 ft)
SSW of a fence corner in the NE corner of the grounds, and 0.91 m (3.0 ft) SE of
the NE corner of the warehouse.  The bench mark is an iron cap riveted on top of
a 1-inch galvanized iron pipe, 0.46 m (1.5 ft) below ground level, and encased
by a 6-inch PVC pipe projecting 0.30 m (1.0 ft) above ground level.  There is a
PVC sleeve around the iron pipe.



                         BENCH MARK STAMPING:  0220 D 1995
                         DESIGNATION:          872 0220 D

MONUMENTATION:           Flange-encased Rod                    VM#:         3945
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   30° 23.2' N (  30.38670)          LONGITUDE:  81° 26.0' W ( -81.43330)


The bench mark is a flange-encased rod set on the property of the U.S. Coast
Guard Station in Mayport, 32.74 m (107.4 ft) SW of the entrance gate to the
base, 15.97 m (52.4 ft) NW of the centerline of State Road A1A, 2.59 m (8.5 ft)
SW of a metal light pole, 0.88 m (2.9 ft) SW of the NE end of the sidewalk, and
0.49 m (1.6 ft) NW of a 1.83 m (6.0 ft) high chainlink fence.  The datum point
is set 15 cm (0.5 ft) below ground level, being the top of a stainless steel rod
driven 19.2 m (63 ft) to refusal, and encased in a 5-inch NOS logo cap.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  8 of 12

                                                                                
Station ID: 8720220                         PUBLICATION DATE:  11/16/2009
Name:       MAYPORT (FERRY DEPOT), SAINT JOHNS RIVER          
            FL
NOAA Chart: 11490                           Latitude:   30° 23.6' N (  30.39330)
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 E 1995
                         DESIGNATION:          872 0220 E

MONUMENTATION:           Tidal Station disk                    VM#:         3946
AGENCY:                  National Ocean Service (NOS)          IDB PID#:  DL5750
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   30° 23.2' N (  30.38639)          LONGITUDE:  81° 26.1' W ( -81.43500)


The bench mark is a flange-encased rod set on the property of the U.S. Coast
Guard Station in Mayport, 53.5 m (175.4 ft) NW of the centerline of State Road
A1A, 11.9 m (39.2 ft) south of the SW corner of the DC Shop Building, 2.2 m (7.2
ft) SE of the SW corner of a 2.0 x 3.0 m (6.0 x 11.0 ft) concrete pad with a two
safety storage buildings attached, and 0.5 m (1.8 ft) NE of a 1.8 m (6.0 ft)
high chain link fence.  The bench mark is a stainless steel rod driven 19.1 m
(62.7 ft) to refusal, encased in a 12.7 cm (5.0 in) NOS logo cap flush with the
ground and 0.1 m (0.3 ft) below the ground; the datum point is a flange-encased
rod recessed 0.9 cm (0.4 in) below ground level.  Access to the datum point is
had through a 5-inch NOS logo cap.



                         BENCH MARK STAMPING:  ST. JO. 308 1992
                         DESIGNATION:          872 0220 ST JO 308

MONUMENTATION:           Tidal Station disk                    VM#:         3948
AGENCY:                  US Army Corps of Engineers (USE)      IDB PID#:  DL5749
SETTING CLASSIFICATION:  Concrete seawall                      OPUS PID#: DL5749
LATITUDE:   30° 23.2' N (  30.38750)          LONGITUDE:  81° 26.1' W ( -81.43472)


The bench mark is a disk set flush at the NE corner of the inner dock at the
U.S. Coast Guard Station in Mayport, located 11.2 m (36.8 ft) WSW of the SE
corner of the Buoy Maintenance Building, 2.8 m (9.3 ft) NNW of the center of a
0.9 m (3.0 ft) around concrete sewer cap, and 0.3 m (1.0 ft) east of the west
face of the seawall.  

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  9 of 12

                                                                                
Station ID: 8720220                         PUBLICATION DATE:  11/16/2009
Name:       MAYPORT (FERRY DEPOT), SAINT JOHNS RIVER          
            FL
NOAA Chart: 11490                           Latitude:   30° 23.6' N (  30.39330)
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:           Flange-encased Rod                    VM#:        14101
AGENCY:                  National Geodetic Survey (NGS)        IDB PID#:  BC2546
SETTING CLASSIFICATION:  Stainless steel rod in sleeve         OPUS PID:        
LATITUDE:   30° 23.6' N (  30.39330)          LONGITUDE:  81° 25.7' W ( -81.42830)


NOTE:  Though this mark may indicate on its NGS Data Sheet which was viewed on
9/15/09, that the mark is monumented as of 1991, FLDEP Doug Thompson requests
this mark not be published because because FLDEP did not recover this mark in
their FLDEP Recovery Program.      The bench mark is a flange-encased rod
located at No. 4610 Ocean Street (Ferry Maintenance Depot), 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 (22.6 ft) NW of the 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 20.4 m (67 ft) to
refusal, and encased in a 5-inch NGS logo cap.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page 10 of 12

                                                                                
Station ID: 8720220                         PUBLICATION DATE:  11/16/2009
Name:       MAYPORT (FERRY DEPOT), SAINT JOHNS RIVER          
            FL
NOAA Chart: 11490                           Latitude:   30° 23.6' N (  30.39330)
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:  Z 324 1970
                         DESIGNATION:          Z 324

MONUMENTATION:           Tidal Station disk                    VM#:        19285
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  BC0710
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID:        
LATITUDE:   30° 22.9' N (  30.38167)          LONGITUDE:  81° 26.3' W ( -81.43833)


The bench mark is a disk set in the top of a concrete post projecting 0.1 m (0.4
ft) above ground level, located 1.4 km (0.9 mi) SW along State Highway A 1 A
from the post office at Mayport, at the junction of a sand road leading westerly
along the south bank of the St. Johns River, at the outside of a long curve in
the highway, (144.0 ft) south of a (30 in) steel pipeline at the south shore of
the St. Johns River, 104.0 ft ENE of the most northern (11.0 in) diameter steel
gate post at the entrance to the Helen Cooper Floyd Little Jetties Park, 27.1 m
(89.0 ft) west of the center line of Ocean Street (State Road A1A), 19.1 m (62.5
ft) north of the center line of the sand road, near the south side of a group of
6 small cedar trees, 9.4 m (31.0 ft) east of the center line of a dim road
leading NW to the St. Johns River, (1.0 ft) SE of a carsonite witness post, 0.6
m (2.0 ft) below the level of the highway.  

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page 11 of 12

                                                                                
Station ID: 8720220                         PUBLICATION DATE:  11/16/2009
Name:       MAYPORT (FERRY DEPOT), SAINT JOHNS RIVER          
            FL
NOAA Chart: 11490                           Latitude:   30° 23.6' N (  30.39330)
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), SAINT JOHNS RIVER based on:

     LENGTH OF SERIES:      215 MONTHS
     TIME PERIOD:           January 1983 - November 2000
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:   


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

     HIGHEST OBSERVED WATER LEVEL (09/09/1964)         =  2.225
     MEAN HIGHER HIGH WATER                     MHHW   =  1.483
     MEAN HIGH WATER                            MHW    =  1.402
     North American Vertical Datum              NAVD88 =  0.917
     MEAN SEA LEVEL                             MSL    =  0.735
     MEAN TIDE LEVEL                            MTL    =  0.723
     MEAN LOW WATER                             MLW    =  0.044
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (01/24/1940)         = -1.037

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     BM EDM 15 MSL 1942                          2.657    1.255
     12 7.861                                    2.962    1.560
     13 8.022                                    3.026    1.624
     EDM 13 1942 MSL                             3.024    1.623
     BM EDM 14 1942 MSL                          1.961    0.560
     MAYPORT 2 RM. NO 1 1946                     2.165    0.763
     0220 A 1978                                 2.179    0.777
     0220 B 1978                                 2.079    0.678
     0220 C 1978                                 2.407    1.005
     872 0220 TIDAL 9                            1.836    0.434
     0220 D 1995                                 2.288    0.886
     0220 E 1995                                 2.201    0.799
     ST. JO. 308 1992                            2.514    1.113
     B 407 1991                                  1.958    0.556
     Z 324 1970                                  2.296    0.894


                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page 12 of 12

                                                                                
Station ID: 8720220                         PUBLICATION DATE:  11/16/2009
Name:       MAYPORT (FERRY DEPOT), SAINT JOHNS RIVER          
            FL
NOAA Chart: 11490                           Latitude:   30° 23.6' N (  30.39330)
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.

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