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National Ocean Service
Datums Page Page 1 of 6
Station ID: 9438478 PUBLICATION DATE: 03/28/2014
Name: SEASIDE (12TH AVE. BRIDGE)
OR
NOAA Chart: 18520 Latitude: 46° 0.0' N ( 46.00000)
USGS Quad: GEARHART Longitude: 123° 55.3' W (-123.92200)
To reach the tide station from Seaside City Hall at the intersection of Broadway
Street and US Highway 101 (Roosevelt Drive), proceed NNE on US Highway 101 for
0.98 km (0.61 mi) to 12th Avenue, turn left and proceed west on 12th Avenue 0.35
km (0.22 mi) to the bridge spanning the Necanicum River. The bench marks are
located along US Highway 101 and near the bridge spanning the Necanicum River on
12th Avenue. The tide gauge is located near the NE end of the bridge.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: TIDAL 2 B 1971
DESIGNATION: 943 8478 TIDAL 2 B
MONUMENTATION: Tidal Station disk VM#: 20742
AGENCY: National Ocean Service (NOS) IDB PID#: SC1038
SETTING CLASSIFICATION: Sidewalk OPUS PID:
LATITUDE: 46° 0.1' N ( 46.00147) LONGITUDE: 123° 55.3' W (-123.92111)
THE BENCH MARK IS A DISK SET IN TOP OF AN OLD FOUNDATION TO A PUMP HOUSE WHICH
IS NOW A SIDEWALK. IT IS 45.52 M (149.3 FT) E OF A LAMP POST ON THE 12TH AVENUE
BRIDGE, 20.49 M (67.2 FT) W OF A STOP SIGN ON THE SW CORNER OF 12TH AVENUE AND
HOLLADAY STREET, 10.26 M (33.7 FT) S OF A UTILITY POLE WITH A LAMP NUMBERED
169302, 5.41 M (17.7 FT) NNE OF THE CENTER OF THE NEW PUMP HOUSE DOORS AND 5.09
M (16.7 FT) S OF THE CENTERLINE OF 12TH AVENUE.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 9438478 PUBLICATION DATE: 03/28/2014
Name: SEASIDE (12TH AVE. BRIDGE)
OR
NOAA Chart: 18520 Latitude: 46° 0.0' N ( 46.00000)
USGS Quad: GEARHART Longitude: 123° 55.3' W (-123.92200)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 8478 A 2013
DESIGNATION: 943 8478 A
MONUMENTATION: Bench Mark disk VM#: 20743
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete bridge abutment OPUS PID:
LATITUDE: 46° 0.1' N ( 46.00144) LONGITUDE: 123° 55.3' W (-123.92167)
THE BENCH MARK IS 46.42 M (152.3 FT) W OF 943 8478 TIDAL 2 B, 32.14 M (105.4 FT)
N OF THE END OF A BLUE PVC OUTFALL INTO THE RIVER, 8.65 M (28.4 FT) SW OF THE
CENTERLINE OF 12TH AVENUE, 1.30 M (4.3 FT) SW OF A LAMPPOST AT THE SE END OF THE
BRIDGE AND 0.23 M (0.8 FT) SW OF CORNER OF CONCRETE UPRIGHT SUPPORT WALL AND
ABOUT 0.41 M (1.3 FT) ABOVE THE GROUND.
BENCH MARK STAMPING: 8478 B 2013
DESIGNATION: 943 8478 B
MONUMENTATION: Bench Mark disk VM#: 20744
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Abutment of a bridge OPUS PID:
LATITUDE: 46° 0.1' N ( 46.00139) LONGITUDE: 123° 55.4' W (-123.92264)
THE BENCH MARK IS A DISK SET IN THE SW CONCRETE WING WALL, 35.51 M (116.5 FT) E
OF THE NE CORNER OF RESTROOM STRUCTURE, 26.30 M (86.3 FT) NE OF A STOP SIGN ON
THE CORNER OF 12TH AVENUE AND NECANICUM ST, 22.50 M (73.8 FT) SSE OF LIGHT POLE
ON THE N SIDE OF 12TH AVENUE, 9.75 M (32.0 FT) SSW OF THE CENTERLINE OF 12TH
AVENUE, 4.45 M (14.6 FT) NE OF THE NE MOST POINT OF ELVIN C GOODMAN PARK SIGN
AND ABOUT 0.85 M (2.8 FT) ABOVE THE GROUND.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 9438478 PUBLICATION DATE: 03/28/2014
Name: SEASIDE (12TH AVE. BRIDGE)
OR
NOAA Chart: 18520 Latitude: 46° 0.0' N ( 46.00000)
USGS Quad: GEARHART Longitude: 123° 55.3' W (-123.92200)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1054 1998
DESIGNATION: OR DOT 1054
MONUMENTATION: Reference Mark disk VM#: 20745
AGENCY: Oregon Department of Transportation IDB PID#:
SETTING CLASSIFICATION: Concrete curb OPUS PID:
LATITUDE: 46° 0.0' N ( 46.00050) LONGITUDE: 123° 55.0' W (-123.91739)
THE BENCH MARK IS A BRASS DISK SET IN A CONCRETE CURB IN THE NW CORNER OF THE
ACCESS ROAD TO THE SHOPPING CENTER, 41.64 M (136.6 FT) NW OF NW PILLAR OF
SHOPPING CENTER, 39.16 M (128.5 FT) S OF CENTER OF S SIDE OF FACTORY OUTLET
SIGN, 25.31 M (83.0 FT) W OF A FIRE HYDRANT, 12.15 M (39.9 FT) S OF THE
CENTERLINE OF ACCESS ROAD AND ABOUT 0.16 M (0.5 FT) ABOVE THE STREET.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 9438478 PUBLICATION DATE: 03/28/2014
Name: SEASIDE (12TH AVE. BRIDGE)
OR
NOAA Chart: 18520 Latitude: 46° 0.0' N ( 46.00000)
USGS Quad: GEARHART Longitude: 123° 55.3' W (-123.92200)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: H 711 1987
DESIGNATION: H 711
MONUMENTATION: Flange-encased Rod VM#: 20746
AGENCY: National Ocean Service (NOS) IDB PID#: SC1037
SETTING CLASSIFICATION: Stainless steel rod w/o sleeve OPUS PID:
LATITUDE: 46° 0.6' N ( 46.00946) LONGITUDE: 123° 54.8' W (-123.91400)
FROM THE INTERSECTION OF US HIGHWAY 101 AND 12TH AVENUE IN SEASIDE, PROCEED N
1.0 KM (0.6 MI) AND TURN LEFT INTO A GRAVEL ACCESS ROAD ACROSS FROM TLC FEDERAL
CREDIT UNION BUILDING. THE BENCH MARK IS FLANGE ENCASED ROD, 46.04 M (151.0 FT)
SW OF W MOST STEEL UPRIGHT FOR OVERHANG AT GAS STATION TO N, 19.0 M (62.3 FT) NW
OF THE CENTERLINE OF US HIGHWAY 101, 12.64 M (41.5 FT) SW OF AN UNNUMBERED
UTILITY POLE, 0.72 M (2.4 FT) E OF E END OF A CHAIN LINK FENCE, 0.30 M (1.0 FT)
SE OF A WITNESS POST. THE DATUM POINT IS SET 9 CM (4 INCHES) BELOW THE GROUND,
BEING THE TOP OF A STAINLESS STEEL ROD, AND ENCASED IN A 5-INCH NATIONAL
GEODETIC SURVEY LOGO COVER.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 9438478 PUBLICATION DATE: 03/28/2014
Name: SEASIDE (12TH AVE. BRIDGE)
OR
NOAA Chart: 18520 Latitude: 46° 0.0' N ( 46.00000)
USGS Quad: GEARHART Longitude: 123° 55.3' W (-123.92200)
T I D A L D A T U M S
Tidal datums at SEASIDE (12TH AVE. BRIDGE) based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: June 2013 - August 2013
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 9439040 ASTORIA, TONGUE POINT, COLUMBIA RIVER
Elevations of tidal datums referred to Mean High Water (MHW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 0.227
MEAN HIGH WATER MHW = 0.000
North American Vertical Datum NAVD88 = -2.226
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MHW
TIDAL 2 B 1971 3.876
8478 A 2013 2.473
8478 B 2013 2.460
1054 1998 3.363
H 711 1987 1.939
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 9438478 PUBLICATION DATE: 03/28/2014
Name: SEASIDE (12TH AVE. BRIDGE)
OR
NOAA Chart: 18520 Latitude: 46° 0.0' N ( 46.00000)
USGS Quad: GEARHART Longitude: 123° 55.3' W (-123.92200)
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.