Bench Mark Sheet for 8723372, SANDS KEY, ELLIOTT KEY 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Superseded Epoch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Small blue map location marker Unpublished bench mark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  6

                                                                                
Station ID: 8723372                         PUBLICATION DATE:  02/26/2004
Name:       SANDS KEY, ELLIOTT KEY                            
            FL
NOAA Chart: 11462                           Latitude:   25° 30.4' N (  25.50670)
USGS Quad:  SOLDIER KEY                     Longitude:  80° 11.3' W ( -80.18830)


To reach the tidal bench marks from Elliott Key Harbor by boat, proceed NNE 5.5
km (3.4 statute mi) to the west side of Sands Key.  The bench marks are on the
west side of Sands Key.  The tide gage and staff were located off the west
northermost point.


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


                 PRIMARY BENCH MARK STAMPING:  NO 3 1974
                         DESIGNATION:          872 3372 TIDAL 3

MONUMENTATION:           Tidal Station disk                    VM#:         5822
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Rock outcrop                          OPUS PID:        
LATITUDE:   25° 30.3' N (  25.50500)          LONGITUDE:  80° 11.3' W ( -80.18830)


The primary bench mark is a disk set flush in outcropping rock, 52 m (170 ft)
south of bench mark SANDS POINT USED NO 2, 26 m (85 ft) SSW of bench mark NO 4
1974, 11 m (35 ft) east of the shoreline, and 0.43 m (1.4 ft) west of a witness
post.



                         BENCH MARK STAMPING:  NO 4 1974
                         DESIGNATION:          872 3372 TIDAL 4

MONUMENTATION:           Tidal Station disk                    VM#:         5823
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Outcropping coral rock                OPUS PID:        
LATITUDE:   25° 30.3' N (  25.50500)          LONGITUDE:  80° 11.3' W ( -80.18830)


The bench mark is a disk set flush in outcropping coral rock, 24.69 m (81.0 ft)
SSW of bench mark SANDS POINT USED NO 2, 8 m (28 ft) east of the shoreline, 2 m
(7 ft) north of a witness sign nailed to a tree, 1.68 m (5.5 ft) NW of a witness
post, and 0.73 m (2.4 ft) west of a witness sign nailed to a tree.

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

                                                                                
Station ID: 8723372                         PUBLICATION DATE:  02/26/2004
Name:       SANDS KEY, ELLIOTT KEY                            
            FL
NOAA Chart: 11462                           Latitude:   25° 30.4' N (  25.50670)
USGS Quad:  SOLDIER KEY                     Longitude:  80° 11.3' W ( -80.18830)


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


                         BENCH MARK STAMPING:  SANDS POINT USED NO 1
                         DESIGNATION:          SANDS POINT RM 1

MONUMENTATION:           Survey disk                           VM#:         5824
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AC3680
SETTING CLASSIFICATION:  Outcropping bedrock                   OPUS PID:        
LATITUDE:   25° 30.4' N (  25.50670)          LONGITUDE:  80° 11.3' W ( -80.18830)


The bench mark is a disk set in a drill hole in an outcropping bedrock located
on the NW side of Sands Key, north of the overhanging mangroves at the
shoreline, and east of the coral rock shoreline, 4 m (14 ft)  SSE of a rock
ledge dropoff, 3 m (9 ft) SE of the high-tide mark, and 0.49 m (1.6 ft) north of
a witness sign.

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

                                                                                
Station ID: 8723372                         PUBLICATION DATE:  02/26/2004
Name:       SANDS KEY, ELLIOTT KEY                            
            FL
NOAA Chart: 11462                           Latitude:   25° 30.4' N (  25.50670)
USGS Quad:  SOLDIER KEY                     Longitude:  80° 11.3' W ( -80.18830)


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


                         BENCH MARK STAMPING:  SANDS POINT USED NO 2
                         DESIGNATION:          SANDS POINT RM 2

MONUMENTATION:           Reference Mark disk                   VM#:         5825
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AC8611
SETTING CLASSIFICATION:  Outcropping bedrock                   OPUS PID:        
LATITUDE:   25° 30.3' N (  25.50500)          LONGITUDE:  80° 11.3' W ( -80.18830)


The bench mark is a disk set in outcropping bedrock located near the coral rock
shoreline, 5 m (15 ft) SSE of a rock ledge dropoff, 4 m (13 ft) east of the
high-tide mark, and 2.44 m (8.0 ft) NNW of a witness post.

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

                                                                                
Station ID: 8723372                         PUBLICATION DATE:  02/26/2004
Name:       SANDS KEY, ELLIOTT KEY                            
            FL
NOAA Chart: 11462                           Latitude:   25° 30.4' N (  25.50670)
USGS Quad:  SOLDIER KEY                     Longitude:  80° 11.3' W ( -80.18830)


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


                         BENCH MARK STAMPING:   
                         DESIGNATION:          SANDS POINT
                         ALIAS:                NO STAMPING 1

MONUMENTATION:           Clay Tile Pipe                        VM#:         5826
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  AC3679
SETTING CLASSIFICATION:  Terra cotta pipe in coral rock        OPUS PID:        
LATITUDE:   25° 30.4' N (  25.50670)          LONGITUDE:  80° 11.3' W ( -80.18830)


The bench mark is an iron pin set inside a terra cotta pipe cemented in coral,
14.63 m (48.0 ft) NNE of bench mark SANDS POINT USED NO 2, 10.85 m (35.6 ft)
west of bench mark SANDS POINT USED NO 1, 4.15 m (13.6 ft) NW of a witness post,
and 0.30 m (1.0 ft) SSE of a rock ledge dropoff.  The bench mark is midway of a
rock ledge on the NW tangent of the prominent NW point of Sands Key.

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

                                                                                
Station ID: 8723372                         PUBLICATION DATE:  02/26/2004
Name:       SANDS KEY, ELLIOTT KEY                            
            FL
NOAA Chart: 11462                           Latitude:   25° 30.4' N (  25.50670)
USGS Quad:  SOLDIER KEY                     Longitude:  80° 11.3' W ( -80.18830)


                            T I D A L   D A T U M S 


Tidal datums at SANDS KEY, ELLIOTT KEY based on:

     LENGTH OF SERIES:      1 MONTH
     TIME PERIOD:           July 1974 - July 1974
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8723350 RAGGED KEY #3


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

     MEAN HIGHER HIGH WATER                     MHHW   =  0.498
     MEAN HIGH WATER                            MHW    =  0.478
     MEAN TIDE LEVEL                            MTL    =  0.256
     MEAN SEA LEVEL                             MSL    =  0.244
     MEAN LOW WATER                             MLW    =  0.034
     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 3 1974                                   1.048    0.570
     NO 4 1974                                   0.905    0.427
     SANDS POINT USED NO 1                       0.561    0.083
     SANDS POINT USED NO 2                       0.744    0.266
     SANDS POINT                                 0.498    0.020


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

                                                                                
Station ID: 8723372                         PUBLICATION DATE:  02/26/2004
Name:       SANDS KEY, ELLIOTT KEY                            
            FL
NOAA Chart: 11462                           Latitude:   25° 30.4' N (  25.50670)
USGS Quad:  SOLDIER KEY                     Longitude:  80° 11.3' W ( -80.18830)


                             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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