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Bench Mark Sheet for 8730667, Alabama Point AL

Superseded Epoch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Small blue map location marker Unpublished bench mark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  5

                                                                                
Station ID: 8730667                         PUBLICATION DATE:  06/13/2003
Name:       ALABAMA POINT, PERDIDO PASS                       
            AL
NOAA Chart: 11382                           Latitude:   30° 16.7' N (  30.27830)
USGS Quad:  FOLEY                           Longitude:  87° 33.3' W ( -87.55500)


To reach the bench marks from the intersection of State Highways 292 and 182,
proceed south on State Highway 182 to the Alabama State line on the beach road
(AKA Perdido Key Drive), then continue west for 3.7 km (2.3 mi) over the Perdido
Pass bridge, then turn right on the west side of the bridge and continue east
parallel to the bridge to the Alabama Marine Police headquarters located at
Perdido Pass. The bench marks are located on State property between the
headquarters and west side of Perdido Pass bridge. The gauge and staff were
located on the pier just west of the west end of the sea wall.


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


                 PRIMARY BENCH MARK STAMPING:  0667 A 1993
                         DESIGNATION:          873 0667 A

MONUMENTATION:           Tidal Station disk                    VM#:        12716
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Concrete sea wall                     OPUS PID:        
LATITUDE:   30° 16.7' N (  30.27831)          LONGITUDE:  87° 33.3' W ( -87.55500)


The primary bench mark is a disk set in a concrete sea wall at the Alabama
Marine Police station, 15.45 m (50.7 ft) west of the NW corner of a concrete
block fuel drum, 5.27 m (17.3 ft) east of the wooden pier, and 0.3 m (1 ft)
south of the north edge of the sea wall.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  5

                                                                                
Station ID: 8730667                         PUBLICATION DATE:  06/13/2003
Name:       ALABAMA POINT, PERDIDO PASS                       
            AL
NOAA Chart: 11382                           Latitude:   30° 16.7' N (  30.27830)
USGS Quad:  FOLEY                           Longitude:  87° 33.3' W ( -87.55500)


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


                         BENCH MARK STAMPING:  0667 B 1993
                         DESIGNATION:          873 0667 B

MONUMENTATION:           Tidal Station disk                    VM#:        12717
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Concrete sea wall                     OPUS PID:        
LATITUDE:   30° 16.7' N (  30.27833)          LONGITUDE:  87° 33.3' W ( -87.55500)


The bench mark is a disk set in a concrete sea wall at the Alabama Marine Police
station, 25.54 m (83.8 ft) north of the NE corner of a concrete helicopter pad,
4.45 m (14.6 ft) east of an anchored chain link fence, and 0.6 m (2 ft) south of
the north edge of the sea wall.



                         BENCH MARK STAMPING:  0667 C 1993
                         DESIGNATION:          873 0667 C

MONUMENTATION:           Tidal Station disk                    VM#:        12718
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Concrete sea wall                     OPUS PID:        
LATITUDE:   30° 16.7' N (  30.27830)          LONGITUDE:  87° 33.3' W ( -87.55500)


The bench mark is a disk set in a concrete sea wall at the Alabama Marine Police
station, 37.58 m (123.3 ft) north of the centerline of Perdido Pass bridge
measured from underneath the bridge, 33.04 m (108.4 ft) east of the SE corner of
a concrete helicopter pad, and 0.67 m (2.2 ft) west of the east edge of the sea
wall.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  5

                                                                                
Station ID: 8730667                         PUBLICATION DATE:  06/13/2003
Name:       ALABAMA POINT, PERDIDO PASS                       
            AL
NOAA Chart: 11382                           Latitude:   30° 16.7' N (  30.27830)
USGS Quad:  FOLEY                           Longitude:  87° 33.3' W ( -87.55500)


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


                         BENCH MARK STAMPING:  0667 D 1993
                         DESIGNATION:          873 0667 D

MONUMENTATION:           Tidal Station disk                    VM#:        12719
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Concrete pad                          OPUS PID:        
LATITUDE:   30° 16.7' N (  30.27830)          LONGITUDE:  87° 33.3' W ( -87.55500)


The bench mark is a disk set in a concrete helicopter pad at the Alabama Marine
Police station, 29.90 m (98.1 ft) north of the second bridge support east of the
west end of the bridge, 12.22 m (40.1 ft) SE of the NW corner of the pad, and
8.53 m (28.0 ft) east of the SW corner of the pad.



                         BENCH MARK STAMPING:  0667 E 1993
                         DESIGNATION:          873 0667 E

MONUMENTATION:           Tidal Station disk                    VM#:        12720
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Concrete porch                        OPUS PID:        
LATITUDE:   30° 16.7' N (  30.27830)          LONGITUDE:  87° 33.3' W ( -87.55500)


The bench mark is a disk set in a concrete porch at the Alabama Marine Police
station, 5.39 m (17.7 ft) SW of the entrance to the Alabama Marine Police
headquarters, 2.10 m (6.9 ft) south of the SW corner of the headquarters, and
0.76 m (2.5 ft) NW of the Alabama Marine Police sign.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  5

                                                                                
Station ID: 8730667                         PUBLICATION DATE:  06/13/2003
Name:       ALABAMA POINT, PERDIDO PASS                       
            AL
NOAA Chart: 11382                           Latitude:   30° 16.7' N (  30.27830)
USGS Quad:  FOLEY                           Longitude:  87° 33.3' W ( -87.55500)


                            T I D A L   D A T U M S 


Tidal datums at ALABAMA POINT, PERDIDO PASS based on:

     LENGTH OF SERIES:      4 MONTHS
     TIME PERIOD:           December 1993 - March 1994
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8729840 PENSACOLA, PENSACOLA BAY


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

     MEAN HIGHER HIGH WATER                     MHHW   =  0.262
     MEAN HIGH WATER                            MHW    =  0.250
     MEAN TIDE LEVEL                            MTL    =  0.129
     MEAN SEA LEVEL                             MSL    =  0.126
     MEAN LOW WATER                             MLW    =  0.007
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     0667 A 1993                                 1.459    1.209
     0667 B 1993                                 1.461    1.211
     0667 C 1993                                 1.470    1.220
     0667 D 1993                                 3.401    3.151
     0667 E 1993                                 3.021    2.771


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

                                                                                
Station ID: 8730667                         PUBLICATION DATE:  06/13/2003
Name:       ALABAMA POINT, PERDIDO PASS                       
            AL
NOAA Chart: 11382                           Latitude:   30° 16.7' N (  30.27830)
USGS Quad:  FOLEY                           Longitude:  87° 33.3' W ( -87.55500)


                             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 8730667 Alabama Point, AL

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