U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
PUBLICATION DATE: 09/13/1985
Station ID: 9446828 SUPERCEDED DATE: 04/21/2003
Name: DUPONT WHARF, NISQUALLY REACH
WASHINGTON
NOAA Chart: 18448 Latitude: 47° 7.1' N
USGS Quad: NISQUALLY Longitude: 122° 40.0' W
To reach the tidal bench marks from Steilacoom, proceed 5.3 miles (8.5 km) south
along the Burlington Northern Railroad to the Dupont Wharf, Nisqually Reach,
Washington. The bench marks are located in the area around the railroad tracks.
The tide gage and staff were located on the Dupont Wharf.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 3 1935
MONUMENTATION: Survey Disk VM#: 9180
AGENCY: PID#: SY0739
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is set in the top of the NE side of the east one of a group of 6
x 6 foot (2 x 2 m) concrete foundations supporting a wooden tower for an
overhead conveyor to the Dupont Wharf, 82 feet (25 m) NW of the NW rail of the
NW main track, 69.3 feet (21.1 m) west of the west rail of a narrow gauge
railroad leading onto the Dupont Wharf, 68 feet (21 m) west of the center of the
NW end of a narrow gauge railroad tunnel under the Burlington-Northern railroad,
60.6 feet (18.5 m) NE of Bench Mark Tidal 6 1973, 36 feet (11 m) lower than the
main tracks, 2.5 feet (0.8 m) NW of the east corner of the foundation, and 2.5
feet (0.8 m) above ground level.
BENCH MARK STAMPING: NO 4 1935
MONUMENTATION: Survey Disk VM#: 9181
AGENCY: PID#: SY0740
SETTING CLASSIFICATION: Concrete Wing Wall
The bench mark is set in the top of the SE end of a 5 x 5 foot (2 x 2 m)
concrete box culvert of Sequalitchew Creek, 200 feet (61 m) SE across the
railroad from Bench Mark Tidal 6 1973, 87 feet (26 m) SE of the SE rail of the
SE tracks (slope measurement), 48.3 feet (14.7 m) SW of the SW rail of the
narrow gage railroad to the Dupont Wharf, 38 feet (12 m) south of the SE end of
the south concrete wing wall of a narrow gauge railroad tunnel, 1.5 feet (0.5 m)
NW of the NW edge of the SE concrete head wall, 0.9 foot (0.3 m) SW of the NE
edge of the culvert, and 40 feet (12 m) lower than the main tracks.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
PUBLICATION DATE: 09/13/1985
Station ID: 9446828 SUPERCEDED DATE: 04/21/2003
Name: DUPONT WHARF, NISQUALLY REACH
WASHINGTON
NOAA Chart: 18448 Latitude: 47° 7.1' N
USGS Quad: NISQUALLY Longitude: 122° 40.0' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: TIDAL 6 1973
MONUMENTATION: Survey Disk VM#: 9182
AGENCY: PID#: SY0738
SETTING CLASSIFICATION: Concrete Headwall
The bench mark is set in the top of the NW end of a 5 x 5 foot (2 x 2 m)
concrete box culvert of Sequalitchew Creek, 78 feet (24 m) NW of the NW rail of
the NW track, 60.6 feet (18.5 m) SW of Bench Mark NO 3 1935, 4.3 feet (1.3 m) SE
of the SE edge of the NW concrete headwall, 3.5 feet (1.1 m) SW of the NE edge
of the culvert, and 40 feet (12 m) lower than the main tracks.
BENCH MARK STAMPING: DUP 1924 44.987
MONUMENTATION: Survey Disk VM#: 9183
AGENCY: PID#: SY0741
SETTING CLASSIFICATION: Concrete Post
The bench mark is set in a concrete post 12 poles NE of milepost 21 along the
Burlington-Northern railroad, 360 feet (110 m) NE of the Dupont Wharf, 43.3 feet
(13.2 m) NW of the NW rail of the NW main track, 37 feet (11 m) NE of Bench Mark
DUP NO 2 1924 45.581, 34.3 feet (10.5 m) north of the twelfth telephone pole
from milepost 21, 2 feet (1 m) lower than the tracks, and 0.3 foot (0.1 m) above
grade.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
PUBLICATION DATE: 09/13/1985
Station ID: 9446828 SUPERCEDED DATE: 04/21/2003
Name: DUPONT WHARF, NISQUALLY REACH
WASHINGTON
NOAA Chart: 18448 Latitude: 47° 7.1' N
USGS Quad: NISQUALLY Longitude: 122° 40.0' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: DUP NO 2 1924 45.581
MONUMENTATION: Survey Disk VM#: 9184
AGENCY: PID#: SY0743
SETTING CLASSIFICATION: Concrete Post
The bench mark is set in a concrete post 12 poles NE of milepost 21 along the
Burlington-Northern railroad, 330 feet (101 m) NE of the Dupont Wharf dock, 43
feet (13 m) NW of the NW rail of the NW main track, 37 feet (11 m) SW of Bench
Mark Dup 1924 44.987, 34.1 feet (10.4 m) WNW of the twelfth telephone pole, 1.2
feet (0.4 m) SE of a steel witness post, 1 foot (0.3 m) lower than the main
tracks, and 0.3 foot (0.1 m) above grade.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
PUBLICATION DATE: 09/13/1985
Station ID: 9446828 SUPERCEDED DATE: 04/21/2003
Name: DUPONT WHARF, NISQUALLY REACH
WASHINGTON
NOAA Chart: 18448 Latitude: 47° 7.1' N
USGS Quad: NISQUALLY Longitude: 122° 40.0' W
T I D A L D A T U M S
Tidal datums at DUPONT WHARF, NISQUALLY REACH based on:
LENGTH OF SERIES: 68 HW + 67 LW
TIME PERIOD: MARCH 8-APRIL 11, 1978
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 (03/08/1978) = 14.86
MEAN HIGHER HIGH WATER MHHW = 13.51
MEAN HIGH WATER MHW = 12.58
MEAN TIDE LEVEL MTL = 7.77
* NATIONAL GEODETIC VERTICAL DATUM NGVD29 = 7.11
MEAN LOW WATER MLW = 2.95
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (05/05/1973) = -3.74
* NGVD reference based on elevations published in Quad N471223, 1985, and NOS
leveling of 1978.
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
NO 3 1935 15.99 3.41
NO 4 1935 15.73 3.15
TIDAL 6 1973 12.87 0.29
DUP 1924 44.987 52.26 39.68
DUP NO 2 1924 45.581 52.84 40.26
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
PUBLICATION DATE: 09/13/1985
Station ID: 9446828 SUPERCEDED DATE: 04/21/2003
Name: DUPONT WHARF, NISQUALLY REACH
WASHINGTON
NOAA Chart: 18448 Latitude: 47° 7.1' N
USGS Quad: NISQUALLY Longitude: 122° 40.0' 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.