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Bench Mark Sheet for 8726657, DAVIS ISLAND, HILLSBOROUGH BAY 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Superseded Epoch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Small blue map location marker Unpublished bench mark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  7

                                                                                
Station ID: 8726657                         PUBLICATION DATE:  02/05/2004
Name:       DAVIS ISLAND, HILLSBOROUGH BAY                    
            FL
NOAA Chart: 11417                           Latitude:   27° 54.5' N (  27.90830)
USGS Quad:  TAMPA                           Longitude:  82° 27.1' W ( -82.45170)


To reach the tidal marks from the Peter O. Knight Airport administration
building on Severn Road, proceed east and then south on Severn Road (around the
seaplane basin) to the Davis Island Yacht Club.  The bench marks are around the
seaplane basin.  The tide station was located on the westernmost pier at the
yacht club.


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


                 PRIMARY BENCH MARK STAMPING:  6657 B 1976
                         DESIGNATION:          872 6657 B TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         6797
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AG7511
SETTING CLASSIFICATION:  Concrete base                         OPUS PID#: AG7511
LATITUDE:   27° 54.5' N (  27.90830)          LONGITUDE:  82° 27.0' W ( -82.45000)


The primary bench mark is a disk set in the concrete base for a former boat
hoist west of the inshore end of the center of three piers located along the
south wall of the seaplane basin, 48 m (158 ft) east of the NW corner of the
seawall, 29 m (95 ft) NE of the NW corner of the yacht club building, and 8.23 m
(27.0 ft) west of a telephone booth.

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

                                                                                
Station ID: 8726657                         PUBLICATION DATE:  02/05/2004
Name:       DAVIS ISLAND, HILLSBOROUGH BAY                    
            FL
NOAA Chart: 11417                           Latitude:   27° 54.5' N (  27.90830)
USGS Quad:  TAMPA                           Longitude:  82° 27.1' W ( -82.45170)


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


                         BENCH MARK STAMPING:  6657 A 1976
                         DESIGNATION:          872 6657 A TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         6796
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AG7512
SETTING CLASSIFICATION:  Sea wall                              OPUS PID#: AG7512
LATITUDE:   27° 54.5' N (  27.90830)          LONGITUDE:  82° 27.1' W ( -82.45170)


The bench mark is a disk set in the top of a concrete seawall at the inshore end
of the westernmost pier located along the south wall of the seaplane basin, 54 m
(177 ft) west of bench mark 6657 B 1976, 49 m (160 ft) NW of the NW corner of
the yacht club building, 0.46 m (1.5 ft) SE of the corner of the seawall, and
0.30 m (1.0 ft) south of the westernmost pier.



                         BENCH MARK STAMPING:  6657 C 1976
                         DESIGNATION:          872 6657 C TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         6798
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  AG7510
SETTING CLASSIFICATION:  Sea wall                              OPUS PID:        
LATITUDE:   27° 54.5' N (  27.90830)          LONGITUDE:  82° 27.0' W ( -82.45000)


The bench mark is a disk set in a concrete seawall west of the inshore end of
the easternmost pier located along the south wall of the seaplane basin, 48 m
(158 ft) NE of NE corner of the yacht club building, and 10.97 m (36.0 ft) SW of
a double-wing boat davit.

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

                                                                                
Station ID: 8726657                         PUBLICATION DATE:  02/05/2004
Name:       DAVIS ISLAND, HILLSBOROUGH BAY                    
            FL
NOAA Chart: 11417                           Latitude:   27° 54.5' N (  27.90830)
USGS Quad:  TAMPA                           Longitude:  82° 27.1' W ( -82.45170)


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


                         BENCH MARK STAMPING:  6657 G 1990
                         DESIGNATION:          872 6657 G TIDAL

MONUMENTATION:           Flange-encased Rod                    VM#:         6801
AGENCY:                  National Ocean Service (NOS)          IDB PID#:  AG9408
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   27° 54.6' N (  27.91000)          LONGITUDE:  82° 26.8' W ( -82.44670)


The bench mark is a flange-encased rod located on the east side of Severn Road
east of a beach area at the eastern shore of the seaplane basin, 110 m (360 ft)
north of the entrance to Davis Island Yacht Club, 6.61 m (21.7 ft) west of a
0.37 m (1.2 ft) diameter cabbage palm, 5.12 m (16.8 ft) east of the centerline
of Severn Road, and 5.12 m (16.8 ft) west of a witness post. The datum point is
the top of a stainless steel rod driven 17.1 m (56 ft) to refusal, and encased
in a PVC pipe and logo cap.

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

                                                                                
Station ID: 8726657                         PUBLICATION DATE:  02/05/2004
Name:       DAVIS ISLAND, HILLSBOROUGH BAY                    
            FL
NOAA Chart: 11417                           Latitude:   27° 54.5' N (  27.90830)
USGS Quad:  TAMPA                           Longitude:  82° 27.1' W ( -82.45170)


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


                         BENCH MARK STAMPING:  KNIGHT NO 2 1946
                         DESIGNATION:          KINGHT RM 2

MONUMENTATION:           Reference Mark disk                   VM#:         6802
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AG6026
SETTING CLASSIFICATION:  Concrete sea wall                     OPUS PID:        
LATITUDE:   27° 54.7' N (  27.91170)          LONGITUDE:  82° 26.9' W ( -82.44830)


The bench mark is a disk set in the east end of a concrete seawall along the
north shore of the seaplane basin, 114 m (375 ft) SE of the airport
administration building, 12.80 m (42.0 ft) west of the extended east/west wall
of a large brick hangar, and 7.62 m (25.0 ft) south of the centerline of the
paved road along the south end of the airport.

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

                                                                                
Station ID: 8726657                         PUBLICATION DATE:  02/05/2004
Name:       DAVIS ISLAND, HILLSBOROUGH BAY                    
            FL
NOAA Chart: 11417                           Latitude:   27° 54.5' N (  27.90830)
USGS Quad:  TAMPA                           Longitude:  82° 27.1' W ( -82.45170)


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


                         BENCH MARK STAMPING:  Q 261 1966
                         DESIGNATION:          Q 261

MONUMENTATION:           Bench Mark disk                       VM#:         6803
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AG6024
SETTING CLASSIFICATION:  Concrete sea wall                     OPUS PID:        
LATITUDE:   27° 54.8' N (  27.91330)          LONGITUDE:  82° 26.8' W ( -82.44670)


The bench mark is a disk set in the top of a former concrete seawall which has
had fill installed around it, 0.2 km (0.1 mi) east of the airport administration
building, 55 m (180 ft) west of the south end of the extended centerline of the
north/south runway, 20.12 m (66.0 ft) SE of the center of the junction of a
paved road and a drive leading to the hangars, and 15.54 m (51.0 ft) SW of a
fence corner.

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

                                                                                
Station ID: 8726657                         PUBLICATION DATE:  02/05/2004
Name:       DAVIS ISLAND, HILLSBOROUGH BAY                    
            FL
NOAA Chart: 11417                           Latitude:   27° 54.5' N (  27.90830)
USGS Quad:  TAMPA                           Longitude:  82° 27.1' W ( -82.45170)


                            T I D A L   D A T U M S 


Tidal datums at DAVIS ISLAND, HILLSBOROUGH BAY based on:

     LENGTH OF SERIES:      1 YEAR
     TIME PERIOD:           June 1990 - May 1991
     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:

     HIGHEST OBSERVED WATER LEVEL (03/03/1991)         =  1.362
     MEAN HIGHER HIGH WATER                     MHHW   =  0.800
     MEAN HIGH WATER                            MHW    =  0.699
     North American Vertical Datum              NAVD88 =  0.523
     MEAN SEA LEVEL                             MSL    =  0.431
     MEAN TIDE LEVEL                            MTL    =  0.421
     MEAN LOW WATER                             MLW    =  0.143
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (01/19/1977)         = -0.622

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     6657 B 1976                                 2.286    1.587
     6657 A 1976                                 1.974    1.275
     6657 C 1976                                 2.039    1.340
     6657 G 1990                                 2.163    1.464
     KNIGHT NO 2 1946                            2.088    1.389
     Q 261 1966                                  2.103    1.405


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

                                                                                
Station ID: 8726657                         PUBLICATION DATE:  02/05/2004
Name:       DAVIS ISLAND, HILLSBOROUGH BAY                    
            FL
NOAA Chart: 11417                           Latitude:   27° 54.5' N (  27.90830)
USGS Quad:  TAMPA                           Longitude:  82° 27.1' W ( -82.45170)


                             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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Products available at 8726657 DAVIS ISLAND, HILLSBOROUGH BAY, FL

Revised: 10/15/2013
NOAA / National Ocean Service
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