Superseded Bench Mark Sheet for 9445478, UNION, HOOD CANAL WA

Present Epoch

Printable version

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  5

                                                   PUBLICATION DATE:  07/13/1988
Station ID: 9445478                                SUPERCEDED DATE:   04/21/2003
Name:       UNION, HOOD CANAL                                 
            WASHINGTON
NOAA Chart: 18476                                  Latitude:         47° 21.5' N
USGS Quad:  POTLATCH                               Longitude:       123°  5.9' W


To reach the tidal bench marks from the Post Office in Union, proceed 328 feet
(100 m) west across State Highway 106 to the Hood Canal Marina building.  The
bench marks are located along State Highway 106.  The tide gage and staff were
located on the pier east of the Hood Canal Marina building.


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


                 PRIMARY BENCH MARK STAMPING:  3 1935

MONUMENTATION:           Survey Disk                               VM#:     9060
AGENCY:                                                            PID#:  SY1271
SETTING CLASSIFICATION:  Concrete Foundation


The bench mark is set in the concrete slab at the southernmost corner of the
Mobile Service station on the north side of State Highway 106, 0.2 mile (0.3 km)
west of the post office, 394 feet (120 m) west of the remains of the Masonic
Hall, 42 feet (13 m) north of the centerline of State Highway 106, 2.5 feet (0.8
m) west of the SE corner of the building, 0.5 foot (0.2 m) south of the south
face of the building, and level with the highway.



                         BENCH MARK STAMPING:  4 1935

MONUMENTATION:           Survey Disk                               VM#:     9061
AGENCY:                                                            PID#:  SY1274
SETTING CLASSIFICATION:  Concrete Retaining Wall


The bench mark is set vertically in the north face of a concrete retaining wall
in front of a private home, 580 feet (177 m) west of the post office, 81 feet
(25 m) SE of the SE corner of the remains of the Masonic Hall, 22 feet (7 m)
south of the centerline of State Highway 106, 3 feet (1 m) east of the west end
of the retaining wall, and 1 foot (0.3 m) above the level of the highway.

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

                                                   PUBLICATION DATE:  07/13/1988
Station ID: 9445478                                SUPERCEDED DATE:   04/21/2003
Name:       UNION, HOOD CANAL                                 
            WASHINGTON
NOAA Chart: 18476                                  Latitude:         47° 21.5' N
USGS Quad:  POTLATCH                               Longitude:       123°  5.9' W


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


                         BENCH MARK STAMPING:  5 1952

MONUMENTATION:           Survey Disk                               VM#:     9062
AGENCY:                                                            PID#:  SY1275
SETTING CLASSIFICATION:  Concrete Foundation


The bench mark is set flush at the center of a 0.7 foot (0.2 m) high concrete
base for an abandoned gasoline pump, directly north across State Highway 106
from the post office, 123 feet (37 m) east of the SE corner of the Union Cafe
building, 80 feet (24 m) north of the NW corner of the post office, 66 feet (20
m) west of the center of a fire hydrant, 40 feet (12 m) north of the centerline
of State Highway 106, and level with the highway.



                         BENCH MARK STAMPING:  BM 1 1972

MONUMENTATION:           Survey Disk                               VM#:     9063
AGENCY:                                                            PID#:  SY1272
SETTING CLASSIFICATION:  Concrete Foundation


The bench mark is set flush in the center of the north end of a 17 x 27 foot (5
x 8 m) concrete slab that served as the floor to an old firehouse adjacent to
and east of the Mobile Gas Station, 0.2 mile (0.3 km) west of the post office,
94 feet (29 m) north of the centerline of State Highway 106, 74 feet (23 m) NW
of power pole U 105 bearing a transformer and a light, 71.4 feet (21.8 m) NE of
Bench Mark 3 1935, 6.0 feet (1.8 m) east of the NW corner of the concrete slab,
and 2 feet (1 m) below the level of the highway.

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

                                                   PUBLICATION DATE:  07/13/1988
Station ID: 9445478                                SUPERCEDED DATE:   04/21/2003
Name:       UNION, HOOD CANAL                                 
            WASHINGTON
NOAA Chart: 18476                                  Latitude:         47° 21.5' N
USGS Quad:  POTLATCH                               Longitude:       123°  5.9' W


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


                         BENCH MARK STAMPING:  NO 7 1973

MONUMENTATION:           Survey Disk                               VM#:     9064
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Foundation


The bench mark is set in concrete slab (walkway) around the Hood Canal Marina
building, next to the building and at the SE corner of the door to the mens
restroom, 16 feet (5 m) back and 6 feet (2 m) over from the corner of the
concrete slab.

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

                                                   PUBLICATION DATE:  07/13/1988
Station ID: 9445478                                SUPERCEDED DATE:   04/21/2003
Name:       UNION, HOOD CANAL                                 
            WASHINGTON
NOAA Chart: 18476                                  Latitude:         47° 21.5' N
USGS Quad:  POTLATCH                               Longitude:       123°  5.9' W


                            T I D A L   D A T U M S 


Tidal datums at UNION, HOOD CANAL based on:

     LENGTH OF SERIES:      5 MONTHS
     TIME PERIOD:           APRIL, JUNE-SEPTEMBER 1977
     TIDAL EPOCH:           1960-1978
     CONTROL TIDE STATION:  9447130 SEATTLE


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

     HIGHEST OBSERVED WATER LEVEL (02/09/1978)         =  14.92
     MEAN HIGHER HIGH WATER                     MHHW   =  11.84
     MEAN HIGH WATER                            MHW    =  10.86
     MEAN TIDE LEVEL                            MTL    =   6.93
   * NATIONAL GEODETIC VERTICAL DATUM           NGVD29 =   6.51
     MEAN LOW WATER                             MLW    =   3.00
     MEAN LOWER LOW WATER                       MLLW   =   0.00
     LOWEST  OBSERVED WATER LEVEL (06/02/1977)         =  -3.89

   * NGVD reference based on elevations published in Quad 471232, 1985, and NOS
     leveling of 1978. 
North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In FEET above:

     Stamping or Designation                    MLLW        MHW

     3 1935                                     18.58      7.72
     4 1935                                     21.45     10.59
     5 1952                                     16.58      5.72
     BM 1 1972                                  15.75      4.89
     NO 7 1973                                  15.55      4.69


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

                                                   PUBLICATION DATE:  07/13/1988
Station ID: 9445478                                SUPERCEDED DATE:   04/21/2003
Name:       UNION, HOOD CANAL                                 
            WASHINGTON
NOAA Chart: 18476                                  Latitude:         47° 21.5' N
USGS Quad:  POTLATCH                               Longitude:       123°  5.9' 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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