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Datums Page Page 1 of 9
Station ID: 9450460 PUBLICATION DATE: 09/27/2011
Name: KETCHIKAN, TONGASS NARROWS
AK
NOAA Chart: 17430 Latitude: 55° 19.9' N ( 55.33183)
USGS Quad: KETCHIKAN B-5 Longitude: 131° 37.6' W (-131.62619)
To reach the tidal bench marks from the Ketchikan, Alaska State Ferry Terminal,
exit the parking area and turn right onto Tongass Avenue. Proceed SE for 3.2 km
(2.0 mi) around the tunnel downtown and turn right onto Front Street and proceed
0.2 km (0.1 mi) then turn left onto Mill Street at the Federal Building and go
0.2 km (0.1 mi) to Stedman Street. Turn right onto Stedman and proceed 1.04 km
(0.65 mi) to the Coast Guard Base, (mile 1/2 on South Tongass Highway). Proceed
0.2 km (0.1 mi) downhill to Machine Shop, turn right and follow counterclockwise
0.2 km (0.1 mi) on pier. The tide house is on the north side (landward) of the
pier adjacent to warehouse. The bench marks were in the vicinity.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 24 1921
DESIGNATION: 945 0460 TIDAL 24
MONUMENTATION: Tidal Station disk VM#: 1165
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Building OPUS PID:
LATITUDE: 55° 20.0' N ( 55.33294) LONGITUDE: 131° 37.6' W (-131.62636)
The primary bench mark is set vertically on the SW side of the concrete U.S.
Coast Guard Administration building, 31.49 m (103.3 ft) NW of a fire hydrant on
the SW side of the Administration building, 20.39 m (66.9 ft) north of the NE
corner of the South Shop building, 5.00 m (16.4 ft) NW of northern-most door on
SW side of the Administration building, 1.41 m (4.6 ft) east of the center of a
ladder leading from the wharf to the water, 0.30 m (1.0 ft) SE of the west
corner of the Administration building, and 0.30 m (1.0 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 9
Station ID: 9450460 PUBLICATION DATE: 09/27/2011
Name: KETCHIKAN, TONGASS NARROWS
AK
NOAA Chart: 17430 Latitude: 55° 19.9' N ( 55.33183)
USGS Quad: KETCHIKAN B-5 Longitude: 131° 37.6' W (-131.62619)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 32 1922
DESIGNATION: 945 0460 TIDAL 32
MONUMENTATION: Tidal Station disk VM#: 1168
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Concrete foundation OPUS PID:
LATITUDE: 55° 20.0' N ( 55.33403) LONGITUDE: 131° 37.6' W (-131.62622)
The bench mark is a disk set in the north edge of the circular concrete
foundation for tank #13 which is the southern most tank inside the Petro Marine
Services facility, 22.40 (73.5 ft) SW of the centerline of Steadman Street, 6.10
m (20.0 ft) west of a ladder leading down the east side of tank #13, and 2.59 m
(8.5 ft) south of the northerly adjacent oil tank.
BENCH MARK STAMPING: NO 37 1956
DESIGNATION: BM NO 37
ALIAS:
MONUMENTATION: Tidal Station disk VM#: 1170
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: AI4914
SETTING CLASSIFICATION: Concrete retaining wall OPUS PID#: AI4914
LATITUDE: 55° 20.0' N ( 55.33292) LONGITUDE: 131° 37.5' W (-131.62542)
The bench mark is a disk set in a concrete retaining wall on the NW side of the
U.S. Coast Guard base entrance road, 26.70 m (87.6 ft) NNE of the eastern most
corner of the U.S. Coast Guard Administration building, 6.40m (21.0 ft) north of
a 15 degree corner in the concrete wall, 3.00 m (9.8 ft) south of the north end
of a steel guard rail, and 0.31 m (1.0 ft) above the entrance road level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 9
Station ID: 9450460 PUBLICATION DATE: 09/27/2011
Name: KETCHIKAN, TONGASS NARROWS
AK
NOAA Chart: 17430 Latitude: 55° 19.9' N ( 55.33183)
USGS Quad: KETCHIKAN B-5 Longitude: 131° 37.6' W (-131.62619)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0460 B 1982
DESIGNATION: 945 0460 B
MONUMENTATION: Tidal Station disk VM#: 1174
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Bedrock outcrop OPUS PID:
LATITUDE: 55° 20.0' N ( 55.33361) LONGITUDE: 131° 37.6' W (-131.62611)
The bench mark is set in a bedrock outcrop at the south end of the Petro Marine
Services tank farm and inside of the facility's chain link fence, 41.45 m (136.0
ft) SW of the centerline of Steadman Road, 23.31m (76.5 ft) ESE of a pair of low
flood lights directed at the logo on tank #13, 11.89 m (39.0 ft) north of the NE
corner of the U.S. Coast Guard Gym, 5.46 m (17.9 ft) west of the chain link
fence around the upper U.S. Coast Guard parking lot, 4.63 m (15.2 ft) south of
the most southerly fuel tank, and 0.61 m (2.0 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 9
Station ID: 9450460 PUBLICATION DATE: 09/27/2011
Name: KETCHIKAN, TONGASS NARROWS
AK
NOAA Chart: 17430 Latitude: 55° 19.9' N ( 55.33183)
USGS Quad: KETCHIKAN B-5 Longitude: 131° 37.6' W (-131.62619)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: BM 1 23.15
DESIGNATION: 945 0460 BM 1 23.15
ALIAS: BM 1 1982
MONUMENTATION: Survey disk VM#: 1176
AGENCY: US Coast Guard (USCG) IDB PID#:
SETTING CLASSIFICATION: Concrete bull rail OPUS PID:
LATITUDE: 55° 19.9' N ( 55.33192) LONGITUDE: 131° 37.5' W (-131.62581)
The bench mark is a disk set in a concrete bull rail that runs from the dock to
the side entrance on the south side of the U.S. Coast Guard South Shop building,
14.50 m (47.6 ft) NNE of a lamp standard set atop a 1.35 m (4.4 ft) diameter x
1.00 m (3.3 ft) high concrete base, 3.90 m (12.8 ft) NE of a red fire hydrant,
0.70 m (2.3 ft) NE of the NE end of a wooden railing, 0.25 m (0.8 ft) SE of the
SE wall of the South Shop building, and 0.27 m (0.9 ft) above ground level.
Note: Met TBM
BENCH MARK STAMPING: 0460 A 1979 RESET 1996
DESIGNATION: 945 0460 A RESET
MONUMENTATION: Tidal Station disk VM#: 13081
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 55° 20.1' N ( 55.33436) LONGITUDE: 131° 37.6' W (-131.62703)
The bench mark is a disk set in a bedrock outcrop in the Petro Marine Services
Tank Farm, 19.81 m (65.0 ft) SW of Stedman Road, 13.69 m (44.9 ft) south of
utility pole #542 located outside the containment wall and chainlink fence, 8.50
m (27.9 ft) SE of the center of three elevated pipes running NE to SW from chain
link fence, 5.79 m (19.0 ft) north of Tank #19, and 1.60 m (5.2 ft) SW from edge
of bedrock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 9
Station ID: 9450460 PUBLICATION DATE: 09/27/2011
Name: KETCHIKAN, TONGASS NARROWS
AK
NOAA Chart: 17430 Latitude: 55° 19.9' N ( 55.33183)
USGS Quad: KETCHIKAN B-5 Longitude: 131° 37.6' W (-131.62619)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4590 D 1996
DESIGNATION: 945 0460 D
MONUMENTATION: Tidal Station disk VM#: 13082
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete foundation OPUS PID:
LATITUDE: 55° 19.9' N ( 55.33225) LONGITUDE: 131° 37.5' W (-131.62517)
The bench mark is a disk set in the concrete foundation of the U.S. Coast Guard
dry dock structure, 55.30 m (181.4 ft) NE of bench mark 945 0460 BM 1 23.15,
11.80 m (38.7 ft) east of the NE corner of the South Shop building, 0.55 m (1.8
ft) NW of the south corner of the dry dock structure, 0.12 m (0.4 ft) east of
the west corner of the concrete footing at the south corner of the drydock, and
0.25 m (0.8 ft) above the ground level.
BENCH MARK STAMPING: 0460 E 2001
DESIGNATION: 945 0460 E
MONUMENTATION: Tidal Station disk VM#: 16465
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Bedrock OPUS PID:
LATITUDE: 55° 20.0' N ( 55.33300) LONGITUDE: 131° 37.5' W (-131.62442)
The bench mark is a disk set in a bedrock cliff along the NE side of Steadman
Street across from the U.S. Coast Guard base and power pole #1542, 82.95 m
(108.1 ft) NW of the centerline of the uphill driveway to the U.S. Coast Guard
barracks, 74.63m (80.8 ft) NW of a stop sign at corner of Steadman Street and
driveway, 54.07 m (177.4 ft) SE of a fire hydrent, and 21.26m (ft) SE of a No
Parking sign bolted to cliff face.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 9
Station ID: 9450460 PUBLICATION DATE: 09/27/2011
Name: KETCHIKAN, TONGASS NARROWS
AK
NOAA Chart: 17430 Latitude: 55° 19.9' N ( 55.33183)
USGS Quad: KETCHIKAN B-5 Longitude: 131° 37.6' W (-131.62619)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0460 F 2004
DESIGNATION: 945 0460 F
MONUMENTATION: Tidal Station disk VM#: 17639
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Retaining wall OPUS PID:
LATITUDE: 55° 20.0' N ( 55.33350) LONGITUDE: 131° 37.5' W (-131.62533)
The bench mark is a disk set flush in the top of a concrete retaining wall that
runs along the east side of the entrance road to the U.S. Coast Guard base,
16.48 m (54.1 ft) south from the north end of the wall, 9.33 m (30.6 ft) north
of the south end of the wall, 8.48 m (27.8 ft) NE from the NE corner of guard
house, 8.04 m (26.4 ft) SW from the center of power pole #01759, 0.84 m (2.8 ft)
west of the west side of the "Force Protection Condition" sign, and 0.92 m (3.0
ft) above the road.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 9
Station ID: 9450460 PUBLICATION DATE: 09/27/2011
Name: KETCHIKAN, TONGASS NARROWS
AK
NOAA Chart: 17430 Latitude: 55° 19.9' N ( 55.33183)
USGS Quad: KETCHIKAN B-5 Longitude: 131° 37.6' W (-131.62619)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: USCG KETCH 2003
DESIGNATION: KETCH 2003
MONUMENTATION: Tidal Station disk VM#: 17988
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Concrete bull rail OPUS PID:
LATITUDE: 55° 19.9' N ( 55.33183) LONGITUDE: 131° 37.6' W (-131.62653)
The bench mark is a disk set in the concrete bull rail at an inflection point of
the pier face at the U.S. Coast Guard dock, 31.40m (103.0 ft) west of the
western most corner of tide house, 29.40 m (96.4 ft) south of the SW corner of
the South Shop building, 17.10 m (56.1 ft) SW of a lamp standard on the north
edge of the dock, 1.20 m (3.9 ft) west of two large yellow bits on the bull
rail, 1.00 m (3.3 ft) NE of the outer wooden dock face, and 0.30 m (1.0 ft)
above the wharf level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 8 of 9
Station ID: 9450460 PUBLICATION DATE: 09/27/2011
Name: KETCHIKAN, TONGASS NARROWS
AK
NOAA Chart: 17430 Latitude: 55° 19.9' N ( 55.33183)
USGS Quad: KETCHIKAN B-5 Longitude: 131° 37.6' W (-131.62619)
T I D A L D A T U M S
Tidal datums at KETCHIKAN, TONGASS NARROWS based on:
LENGTH OF SERIES: 19 YEARS
TIME PERIOD: January 1983 - December 2001
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION:
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (12/02/1967) = 6.495
MEAN HIGHER HIGH WATER MHHW = 4.708
MEAN HIGH WATER MHW = 4.432
MEAN SEA LEVEL MSL = 2.458
MEAN TIDE LEVEL MTL = 2.456
MEAN LOW WATER MLW = 0.479
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (12/14/2008) = -1.605
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
NO 24 1921 7.059 2.626
NO 32 1922 16.495 12.063
NO 37 1956 10.694 6.262
0460 B 1982 18.838 14.406
BM 1 23.15 7.071 2.639
0460 A 1979 RESET 1996 15.177 10.744
4590 D 1996 6.726 2.294
0460 E 2001 16.190 11.758
0460 F 2004 16.189 11.757
USCG KETCH 2003 7.041 2.608
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 9 of 9
Station ID: 9450460 PUBLICATION DATE: 09/27/2011
Name: KETCHIKAN, TONGASS NARROWS
AK
NOAA Chart: 17430 Latitude: 55° 19.9' N ( 55.33183)
USGS Quad: KETCHIKAN B-5 Longitude: 131° 37.6' W (-131.62619)
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.