Bench Mark Sheet for 8760721, Pilottown LA

Superseded Epoch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Small blue map location marker Unpublished bench mark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: 8760721                         PUBLICATION DATE:  03/07/2018
Name:       PILOTTOWN                                         
            LA
NOAA Chart: 11361                           Latitude:   29° 10.7' N (  29.17831)
USGS Quad:  PILOTTOWN                       Longitude:  89° 15.5' W ( -89.25831)


To reach the bench mark from from the Venice, LA marina proceed by boat down the
Mississippi River approximately 14 km (9mi) to Pilottown, LA.


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


                 PRIMARY BENCH MARK STAMPING:  W 279 1971
                         DESIGNATION:          876 0721 W 279

MONUMENTATION:           Survey disk                           VM#:        20235
AGENCY:                  US Coast Gaurd                        IDB PID#:        
SETTING CLASSIFICATION:  Copper Coated Steel Rod.              OPUS PID:        
LATITUDE:   29° 10.6' N (  29.17692)          LONGITUDE:  89° 15.3' W ( -89.25447)


The primary bench mark is located by the main concrete walkway at it's
Southernmost point, 16.0 m (52.5 ft) South of the South corner of the most
Southeasterly house in a row of houses, 7.0 m (23.0 ft) SE of the SE end of the
main concrete walkway and surrounded by 4 creosoted wooden posts, 1.0 m (3.3 ft)
East of the East edge of the main concrete walkway and about 0.3 m higher than
the ground. The bench mark is a disk crimped to a copper coated steel rod driven
32.0 m (104 ft) to substantial resistance and encased in a 4-inch pvc pipe.



                         BENCH MARK STAMPING:  0721 B 1980
                         DESIGNATION:          876 0721 B

MONUMENTATION:           Survey disk                           VM#:        20233
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Concrete Walkway.                     OPUS PID:        
LATITUDE:   29° 10.8' N (  29.17919)          LONGITUDE:  89° 15.4' W ( -89.25617)


The bench mark is a disk set flush on top of the main concrete walkway, 76.0 m
(249.3 ft) SSE of the centerline of the intersection of the river pilots house
North entrance sidewalk and the main sidewalk, 0.2 m (6496.0 ft) ENE of the West
edge of the sidewalk, and about 1.0 m (3.3 ft) higher than the muddy ground.

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

                                                                                
Station ID: 8760721                         PUBLICATION DATE:  03/07/2018
Name:       PILOTTOWN                                         
            LA
NOAA Chart: 11361                           Latitude:   29° 10.7' N (  29.17831)
USGS Quad:  PILOTTOWN                       Longitude:  89° 15.5' W ( -89.25831)


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


                         BENCH MARK STAMPING:  0721 C 1980
                         DESIGNATION:          876 0721 C

MONUMENTATION:           Survey disk                           VM#:        20234
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Concrete Walkway                      OPUS PID:        
LATITUDE:   29° 10.7' N (  29.17781)          LONGITUDE:  89° 15.3' W ( -89.25536)


The benchmark is a disk set flush on top of the main concrete walkway, 254.0 m
(833.3 ft) South of the centerline of the intersection of the river pilots house
North entrance sidewalk and the main sidewalk, 178.0 m (584.0 ft) South of
benchmark 0721 B 1980, 0.2 m (0.7 ft) NE of the West edge of the sidewalk, and
about 1 m (3.3 ft) higher than the muddy ground.



                         BENCH MARK STAMPING:  PILOT
                         DESIGNATION:          876 0721 PILOT

MONUMENTATION:           Survey disk                           VM#:        20236
AGENCY:                  USACE                                 IDB PID#:        
SETTING CLASSIFICATION:  Concrete Helipad.                     OPUS PID#: BBCM63
LATITUDE:   29° 10.7' N (  29.17847)          LONGITUDE:  89° 15.5' W ( -89.25900)


The bench mark is a disk set flush on top of the concrete helipad at the SW
corner, 69.8 m (229.0 ft) South of the SW corner of USCG tower, 58.2 m (190.9
ft) West of West side of fuel storage tank, 8.5 m (27.9 ft) South of North edge
of concrete helipad, 1.2 m (3.9 ft) North of South edge of concrete helipad, 0.9
m East of West edge of concrete helipad and about 2 m (6.6 ft) higher than the
water level.

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

                                                                                
Station ID: 8760721                         PUBLICATION DATE:  03/07/2018
Name:       PILOTTOWN                                         
            LA
NOAA Chart: 11361                           Latitude:   29° 10.7' N (  29.17831)
USGS Quad:  PILOTTOWN                       Longitude:  89° 15.5' W ( -89.25831)


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


                         BENCH MARK STAMPING:  0721 E 2015
                         DESIGNATION:          876 0721 E

MONUMENTATION:           Flange-encased Rod                    VM#:        21737
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Stainless Steel rod                   OPUS PID:        
LATITUDE:   29° 10.8' N (  29.18022)          LONGITUDE:  89° 15.4' W ( -89.25686)


The bench mark is a stainless steel rod located by the main concrete walkway at
the eastern most point of the sidewalk to the radar tower, 38.4 m (126 ft) NE
from the NE most stilt of the pilots building, 14.6 m (48 ft) east of a wooden
utility pole for the radar tower. 8.4 m (27.5 ft) north of a partially burried
chain link fence, 1.5 m (5 ft) east  from the main side walk centerline labeled
11-22-71 a-77, 1.2 m (4 ft) SSE of a 0.3 m (1 ft) x 0.3 m (1 ft) PVC junction
box on the side of main side walk, 0.6 m (2 ft) east of the eastern most edge of
the main side walk, and 0.15 m (0.5 ft) west from a 1.5 m (5 ft) tall 10 cm (4
inch)  x 10 cm (4 inch) wooden pole and witness post. The bench mark is a
stainless stell flange encase rod projected 0.8 m (2.5 ft) above the ground and
about the same height as the side walk driven 27.4 m (89.9 ft) to substantial
resistance and encased in a 4-inch pvc pipe.

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

                                                                                
Station ID: 8760721                         PUBLICATION DATE:  03/07/2018
Name:       PILOTTOWN                                         
            LA
NOAA Chart: 11361                           Latitude:   29° 10.7' N (  29.17831)
USGS Quad:  PILOTTOWN                       Longitude:  89° 15.5' W ( -89.25831)


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


                         BENCH MARK STAMPING:  0721 F 2015
                         DESIGNATION:          876 0721 F

MONUMENTATION:           Tidal Station disk                    VM#:        21738
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  concrete sidewalk                     OPUS PID:        
LATITUDE:   29° 10.8' N (  29.17922)          LONGITUDE:  89° 15.4' W ( -89.25750)


The bench mark is a disk set flush on top of the concrete sidewalk in front of
the generator building for the pilots building, 36.6 m (120 ft) west of the
cargo elevator centerline, 32.6 m (107 ft) SW from the SW most stilt of the
pilots building, 22.6 m (74 ft) west of the staricase centerline in the south
side of the pilots building, 11.9 m (39 ft) east of the fuel tank's fuel gauge,
7.9 m (26 ft) east of the bottom step of the generator building staircase, 1.1 m
(3.5 ft) south of the pilots dock side walk centerline, 0.6 m (2 ft) north of a
light pole. The bench mark is a disk flush to the ground.  

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

                                                                                
Station ID: 8760721                         PUBLICATION DATE:  03/07/2018
Name:       PILOTTOWN                                         
            LA
NOAA Chart: 11361                           Latitude:   29° 10.7' N (  29.17831)
USGS Quad:  PILOTTOWN                       Longitude:  89° 15.5' W ( -89.25831)


                            T I D A L   D A T U M S 


Tidal datums at PILOTTOWN based on:

     LENGTH OF SERIES:      3 YEARS
     TIME PERIOD:           September 2013 - August 2016
     TIDAL EPOCH:           2012-2016
     CONTROL TIDE STATION:  8761724 GRAND ISLE, EAST POINT


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

     HIGHEST OBSERVED WATER LEVEL (08/29/2012)         =  1.720
     MEAN HIGHER HIGH WATER                     MHHW   =  0.262
     MEAN HIGH WATER                            MHW    =  0.260
     MEAN TIDE LEVEL                            MTL    =  0.132
     MEAN SEA LEVEL                             MSL    =  0.130
     MEAN LOW WATER                             MLW    =  0.003
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (12/14/2012)         = -0.526

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     W 279 1971                                  0.201   -0.059
     0721 B 1980                                 1.158    0.898
     0721 C 1980                                 1.121    0.861
     PILOT                                       1.436    1.176
     0721 E 2015                                 1.071    0.811
     0721 F 2015                                 1.364    1.104


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

                                                                                
Station ID: 8760721                         PUBLICATION DATE:  03/07/2018
Name:       PILOTTOWN                                         
            LA
NOAA Chart: 11361                           Latitude:   29° 10.7' N (  29.17831)
USGS Quad:  PILOTTOWN                       Longitude:  89° 15.5' W ( -89.25831)


                             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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