Superseded Bench Mark Sheet for 8725271, IMPERIAL RIVER, HEADWATERS FL

Present Epoch

Printable version

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  4

                                                   PUBLICATION DATE:  08/28/1984
Station ID: 8725271                                SUPERCEDED DATE:   04/21/2003
Name:       IMPERIAL RIVER, HEADWATERS                        
            FLORIDA
NOAA Chart:                                        Latitude:         26° 20.6' N
USGS Quad:  CORKSCRES SW                           Longitude:        81° 46.8' W


To reach the tidal bench marks from the Post Office in Bonita Springs, proceed
north on (Old) U.S. Highway 41 for 0.15 mile (0.2 km) to the north side of the
bridge over the Imperial River.  The gage site is 40.0 feet (12.2 m) NE of the
NE corner of the bridge and the bench marks are in the near area.


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


                 PRIMARY BENCH MARK STAMPING:  5271 A 1978

MONUMENTATION:           Survey Disk                               VM#:     7865
AGENCY:                                                            PID#:  AD6335
SETTING CLASSIFICATION:  Concrete Seawall


The bench mark is 30.0 feet (9.1 m) NE of the NE corner of the bridge, set flush
into the concrete sea wall.



                         BENCH MARK STAMPING:  5271 B 1978

MONUMENTATION:           Survey Disk                               VM#:     7866
AGENCY:                                                            PID#:  AD6334
SETTING CLASSIFICATION:  Concrete Step


The bench mark is 275.0 feet (83.8 m) SW of Bench Mark 5271 C 1978, 210.0 feet
(64.0 m) north of the north end of the bridge over the Imperial River, 67.0 feet
(20.4 m) west of the centerline of (Old) U.S. Highway 41 and 13.0 feet (4.0 m)
SE of the entrance door of Everglades Wonder Gardens.  The bench mark is set
flush into the first concrete step.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  4

                                                   PUBLICATION DATE:  08/28/1984
Station ID: 8725271                                SUPERCEDED DATE:   04/21/2003
Name:       IMPERIAL RIVER, HEADWATERS                        
            FLORIDA
NOAA Chart:                                        Latitude:         26° 20.6' N
USGS Quad:  CORKSCRES SW                           Longitude:        81° 46.8' W


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


                         BENCH MARK STAMPING:  5271 C 1978

MONUMENTATION:           Survey Disk                               VM#:     7867
AGENCY:                                                            PID#:  AD6332
SETTING CLASSIFICATION:  Concrete Post


The bench mark is north of the bridge over the Imperial River, 275.0 feet (83.8
m) NE of Bench Mark 5271 B 1978, 35.0 feet (10.7 m) east of the centerline of
(Old) U.S. Highway 41, 31.0 feet (9.4 m) WNW of the NW corner of the Pittman
Funeral Home building and 3.5 feet (1.1 m) NE of a utility pole.  The bench mark
is set into the top of a concrete post.



                         BENCH MARK STAMPING:  5271 D 1978

MONUMENTATION:           Survey Disk                               VM#:     7868
AGENCY:                                                            PID#:  AD6333
SETTING CLASSIFICATION:  Concrete Step


The bench mark is north of the bridge over the Imperial River, 315.0 feet (96.0
m) NW of Bench Mark 5271 C 1978 and 60.0 feet (18.3 m) west of the centerline of
(Old) U.S. Highway 41.  The bench mark is set flush into the first concrete step
of the Bonita Shoe Store.



                         BENCH MARK STAMPING:  M 244 1965

MONUMENTATION:           Survey Disk                               VM#:     7869
AGENCY:                                                            PID#:  AD1314
SETTING CLASSIFICATION:  Concrete Abutment


The bench mark is at Bonita Springs, on the west end of the south abutment of
the Atlantic Coastline Railroad bridge over the Imperial River, 375.0 feet
(114.3 m) west of the centerline of (Old) U.S. Highway 41, 10.0 feet (3.05 m)
west of the rail and 0.3 feet (0.09 m) east of the west face of the abutment,
4.0 feet (1.2 m) below the track surface.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  4

                                                   PUBLICATION DATE:  08/28/1984
Station ID: 8725271                                SUPERCEDED DATE:   04/21/2003
Name:       IMPERIAL RIVER, HEADWATERS                        
            FLORIDA
NOAA Chart:                                        Latitude:         26° 20.6' N
USGS Quad:  CORKSCRES SW                           Longitude:        81° 46.8' W


                            T I D A L   D A T U M S 


Tidal datums at IMPERIAL RIVER, HEADWATERS based on:

     LENGTH OF SERIES:      5 MONTHS
     TIME PERIOD:           MARCH-JULY 1978
     TIDAL EPOCH:           1960-1978
     CONTROL TIDE STATION:  8725110 NAPLES


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

     HIGHEST OBSERVED WATER LEVEL (08/18/1978)         =   1.83
     MEAN HIGHER HIGH WATER                     MHHW   =   0.96
     MEAN HIGH WATER                            MHW    =   0.78
     MEAN TIDE LEVEL                            MTL    =   0.44
     MEAN LOW WATER                             MLW    =   0.10
     MEAN LOWER LOW WATER                       MLLW   =   0.00
     LOWEST  OBSERVED WATER LEVEL (03/18/1978)         =  -0.89

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In FEET above:

     Stamping or Designation                    MLLW        MHW

     5271 A 1978                                 3.95      3.17
     5271 B 1978                                 7.88      7.10
     5271 C 1978                                 7.56      6.78
     5271 D 1978                                 8.61      7.83
     M 244 1965                                  8.33      7.55


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

                                                   PUBLICATION DATE:  08/28/1984
Station ID: 8725271                                SUPERCEDED DATE:   04/21/2003
Name:       IMPERIAL RIVER, HEADWATERS                        
            FLORIDA
NOAA Chart:                                        Latitude:         26° 20.6' N
USGS Quad:  CORKSCRES SW                           Longitude:        81° 46.8' W


                             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 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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