Published Bench Mark Sheet for 9454374 BUSBY ISLAND, PRINCE WILLIAM SOUND ALASKA
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
Station ID: 9454374 PUBLICATION DATE: 04/19/2005
Name: BUSBY ISLAND, PRINCE WILLIAM SOUND
ALASKA
NOAA Chart: 16707 Latitude: 60° 53.9' N
USGS Quad: CORDOVA (D-8) Longitude: 146° 46.9' W
To reach the benchmarks from Valdez, AK, proceed West throught the Port of
Valdez, and south through Valdez Arm to Tatilek Narrows (21 miles). Proceed to
the NE region of island, approximately at 60 53' 33.0"N, 146 58' 18.0W. The
bench marks are located in the vicinity and the tide gauge was located on the
beach.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 4374 A 2004
DESIGNATION: 945 4374 A
MONUMENTATION: Tidal Station disk VM#: 17768
AGENCY: National Ocean Service (NOS) PID:
SETTING CLASSIFICATION: Bedrock
The benchmark is a disk set flushed in bedrock in the seward most ledge, 121.71
m (41.7 ft) (330 magnetic) from the high point of the ledge, 7.59 m (24.9 ft)
(230 magnetic) from the most prominent rock on the shore, and 1.37 m (4.5 ft)
above apparent mean high water line.
BENCH MARK STAMPING: 4374 B 2004
DESIGNATION: 945 4374 B
MONUMENTATION: Tidal Station disk VM#: 17769
AGENCY: National Ocean Service (NOS) PID:
SETTING CLASSIFICATION: Bedrock
The benchmark is set flush in bedrock in the inland most boulder, 80.31 m (263.5
ft) (340 magnetic) from BM A, 12.34 m (40.5 ft) (15 magnetic) from the high
point of the most prominent ledge to the boulder, and 1.01 m (3.3 ft) above the
apparent mean high water line.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
Station ID: 9454374 PUBLICATION DATE: 04/19/2005
Name: BUSBY ISLAND, PRINCE WILLIAM SOUND
ALASKA
NOAA Chart: 16707 Latitude: 60° 53.9' N
USGS Quad: CORDOVA (D-8) Longitude: 146° 46.9' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4374 C 2004
DESIGNATION: 943 4374 C
MONUMENTATION: Tidal Station disk VM#: 17770
AGENCY: National Ocean Service (NOS) PID:
SETTING CLASSIFICATION: Bedrock
The benchmark is a disk set flush in bedrock in a ledge, 100.28 m (329.0 ft)
(238 magnetic) from BM A, 24.96 m (81.9 ft) (292 magnetic) from BM B, 18.04 m
(59.2 ft) (80 magnetic) from the high point of the most prominent rock, and 1.80
m (5.9 ft) above the apparent mean high water line.
BENCH MARK STAMPING: 4374 D 2004
DESIGNATION: 945 4374 D
MONUMENTATION: Tidal Station disk VM#: 17771
AGENCY: National Ocean Service (NOS) PID:
SETTING CLASSIFICATION: Bedrock
The bench mark is a disk set in bedrock in a prominent boulder, 140.39 m (460.6
ft) (52 magnetic) from BM A, 67.39 m (221.1 ft) (255 magnetic) from the large
rock in which BM E is set, 50.14 m (164.5 ft) (98 magnetic) from BM C, and 1.01
m (3.3 ft) above the apparent mean high water line.
BENCH MARK STAMPING: 4374 E 2004
MONUMENTATION: Tidal Station disk VM#: 17772
AGENCY: National Ocean Service (NOS) PID:
SETTING CLASSIFICATION: Bedrock
The bench mark is a disk set in bedrock located in a ledge 451.26 m (1480.5 ft)
(288 magnetic) from the NW point of Busby Island, (42 magnetic) to Black Point,
200.56 m (658.0 ft) (47 magnetic) from BM A and 2.10 m (6.9 ft) above the
apparent mean high water line.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
Station ID: 9454374 PUBLICATION DATE: 04/19/2005
Name: BUSBY ISLAND, PRINCE WILLIAM SOUND
ALASKA
NOAA Chart: 16707 Latitude: 60° 53.9' N
USGS Quad: CORDOVA (D-8) Longitude: 146° 46.9' W
T I D A L D A T U M S
Tidal datums at BUSBY ISLAND, PRINCE WILLIAM SOUND based on:
LENGTH OF SERIES: 2 MONTHS
TIME PERIOD: August 2004 - September 2004
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 9451600 SITKA, BARONOF ISLAND, SITKA SOUND
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER (MHHW) = 3.632
MEAN HIGH WATER (MHW) = 3.359
MEAN SEA LEVEL (MSL) = 1.938
MEAN TIDE LEVEL (MTL) = 1.904
MEAN LOW WATER (MLW) = 0.448
MEAN LOWER LOW WATER (MLLW) = 0.000
National Geodetic Vertical Datum (NGVD 29)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
4374 A 2004 4.168 0.809
4374 B 2004 4.656 1.297
4374 C 2004 4.416 1.057
4374 D 2004 4.229 0.870
4374 E 2004 4.631 1.272
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
Station ID: 9454374 PUBLICATION DATE: 04/19/2005
Name: BUSBY ISLAND, PRINCE WILLIAM SOUND
ALASKA
NOAA Chart: 16707 Latitude: 60° 53.9' N
USGS Quad: CORDOVA (D-8) Longitude: 146° 46.9' 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 (NAVD 88).
NGVD 29 is a fixed datum adopted as a national standard geodetic reference for
heights but is now considered superseded. NGVD 29 is sometimes referred to as
Sea Level Datum of 1929 or as Mean Sea Level on some early issues of Geological
Survey Topographic Quads. NGVD 29 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 NGVD 29 are available from the National
Geodetic Survey (NGS) data base via the World Wide Web at
National Geodetic Survey.
NAVD 88 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. NAVD 88 replaces NGVD 29 as the national
standard geodetic reference for heights. Bench mark elevations relative to
NAVD 88 are available from NGS through the World Wide Web at
National Geodetic Survey.
NGVD 29 and NAVD 88 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 NAVD 88 elevation is shown on the Elevations of Tidal Datums Table Referred
to MLLW only when two or more of the bench marks listed have NAVD 88 elevations.
The NAVD 88 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, NAVD 88 bench mark elevations computed indirectly from the tidal
datums elevation table may differ slightly from NAVD 88 elevations listed for
each bench mark in the NGS database.
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