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Bench Mark Sheet for 9451054, Port Alexander AK

Superseded Epoch

Large map location marker Station Location
Small red map location marker Published bench mark
Small blue map location marker Unpublished bench mark

Bench mark positions only appear on the map if their coordinates in the CO-OPS database are at the precision of degrees/minutes/seconds/and tenths of seconds. If the coordinates are less precise, the mark will not appear.

Printable version

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  8

                                                                                
Station ID: 9451054                         PUBLICATION DATE:  09/19/2018
Name:       PORT ALEXANDER, BARANOF ISLAND                    
            AK
NOAA Chart: 17331                           Latitude:   56° 14.8' N (  56.24670)
USGS Quad:  PORT ALEXANDER                  Longitude: 134° 38.8' W (-134.64700)


From the seaplane base at Sitka, Alaska, proceed 120 km (65 nm) SSE to the
community of Port Alexander. From the seaplane float located on the east side of
the outer cove, proceed 120 m (400 ft) up the state dock towards the boardwalk.
The tide house is located at the base of the fixed pier at the start of the
boardwalk. The bench marks are located along the shoreline of the inner cove and
out to the point forming the entrance to Port Alexander.


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


                 PRIMARY BENCH MARK STAMPING:   
                         DESIGNATION:          945 1054  TIDAL 1

MONUMENTATION:           Bench Mark disk                       VM#:        18470
AGENCY:                  US Coast and Geodetic Survery
                         (USC&GS)                              IDB PID#:        
SETTING CLASSIFICATION:  Rock outcrop                          OPUS PID#: BBDC38
LATITUDE:   56° 14.7' N (  56.24522)          LONGITUDE: 134° 38.8' W (-134.64742)


The primary bench mark is a disk set flush in the highest flat point of a
bedrock outcropping at the end of the trail leading south from Port Alexander on
the east side of the bay, 40.95 m (134.3 ft) SSE of the west corner 12" piling
bracing the 2.15 m (7.1 ft) high bulkhead supporting the ACS/Alascom satellite
dish, 30.70 m (100.7 ft) NW of the center of the concrete pad supporting the
Earth Scope plate tectonic GPS station antenna, 8.30 m (27.2 ft) north of the
north edge of the F/V Sarah Maria memorial plaque, and 0.70 m (2.3 ft) above
beach level.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  8

                                                                                
Station ID: 9451054                         PUBLICATION DATE:  09/19/2018
Name:       PORT ALEXANDER, BARANOF ISLAND                    
            AK
NOAA Chart: 17331                           Latitude:   56° 14.8' N (  56.24670)
USGS Quad:  PORT ALEXANDER                  Longitude: 134° 38.8' W (-134.64700)


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


                         BENCH MARK STAMPING:  1054 A 2007
                         DESIGNATION:          945 1054 A

MONUMENTATION:           Bench Mark disk                       VM#:        18472
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Concrete slab                         OPUS PID:        
LATITUDE:   56° 14.8' N (  56.24661)          LONGITUDE: 134° 38.9' W (-134.64769)


The bench mark is a disk set flush in the SW corner of the 1.83 m x 2.44 m (6.0
ft x 8.0 ft) concrete slab supporting the tide house, 24.60 m (80.7 ft) WSW of
the south leg of the microwave tower on the east side of the bay at Port
Alexander, 20.23 m (66.4 ft) NE of a brown wooden building that houses the
generator that powers the ACS/Alascom equipment, 3.39 m (11.1 ft) south of the
south side of the boardwalk leading out to the city pier, 0.31 m (1.0 ft) north
of the south edge of the concrete slab and 0.18 m (0.60 ft) east of the west
edge of the concrete slab.  Note - This bench mark is also used as the Met TBM
for this station.



                         BENCH MARK STAMPING:  1054 B 2007
                         DESIGNATION:          945 1054 B

MONUMENTATION:           Bench Mark disk                       VM#:        18473
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Concrete slab                         OPUS PID:        
LATITUDE:   56° 14.9' N (  56.24750)          LONGITUDE: 134° 38.8' W (-134.64722)


The bench mark is a disk set flush in the north side of the flat section of a
concrete boat ramp, 9.42 m (30.9 ft) NNW of the NE corner of a large green and
brown house with a metal garage door facing the bay, 7.35 m (24.1 ft) WSW of the
SW corner of the "J&L Gifts and Antiques" building, 2.46 m (8.1 ft)  north of
the SW end of a wooden retaining wall and 1.50 m (4.9 ft) east of the
approximate high water line.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  8

                                                                                
Station ID: 9451054                         PUBLICATION DATE:  09/19/2018
Name:       PORT ALEXANDER, BARANOF ISLAND                    
            AK
NOAA Chart: 17331                           Latitude:   56° 14.8' N (  56.24670)
USGS Quad:  PORT ALEXANDER                  Longitude: 134° 38.8' W (-134.64700)


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


                         BENCH MARK STAMPING:  1054 C 2007
                         DESIGNATION:          945 1054 C

MONUMENTATION:           Bench Mark disk                       VM#:        18474
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Rock outcrop                          OPUS PID:        
LATITUDE:   56° 14.9' N (  56.24858)          LONGITUDE: 134° 38.9' W (-134.64772)


The bench mark is a disk set flush in a small crevice of a flat-topped rock
outcrop, 23.94 m (78.5 ft) NNW of the NW corner of the gray house belonging to
Juanita Hendrix, 18.62 m (61.1 ft) WSW of the west side of the small boardwalk
that splits off the main boardwalk and leads to a gray wooden out-building with
a wooden ramp leading to the water next door to the gray house, 15.64 m (51.3
ft) south of the SW corner of the gray wooden out-building with a wooden ramp
leading to the water next door to the gray house.



                         BENCH MARK STAMPING:  1054 D 2007
                         DESIGNATION:          945 1054 D

MONUMENTATION:           Bench Mark disk                       VM#:        18475
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Bedrock outcrop                       OPUS PID:        
LATITUDE:   56° 14.9' N (  56.24853)          LONGITUDE: 134° 38.8' W (-134.64728)


The bench mark is a disk set flush in a flat ledge of a large bedrock outcrop on
the east side of the boardwalk, 11.33 m  (37.2 ft) north of the north corner of
a small gray wooden fuel shed on the west side of the boardwalk, 9.77 m (32.1
ft) south of the south side of the first entrance to the "Laughing Raven Lodge"
where the boardwalk angles up the hill, 8.58 m (28.1 ft) east of NE corner of
the gray house, 0.23 m (0.8 ft) east of the east side of the boardwalk, and 0.55
m (1.8 ft) above the boardwalk.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  8

                                                                                
Station ID: 9451054                         PUBLICATION DATE:  09/19/2018
Name:       PORT ALEXANDER, BARANOF ISLAND                    
            AK
NOAA Chart: 17331                           Latitude:   56° 14.8' N (  56.24670)
USGS Quad:  PORT ALEXANDER                  Longitude: 134° 38.8' W (-134.64700)


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


                         BENCH MARK STAMPING:  1054 E 2007
                         DESIGNATION:          945 1054 E

MONUMENTATION:           Bench Mark disk                       VM#:        18476
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Rock outcrop                          OPUS PID:        
LATITUDE:   56° 14.7' N (  56.24492)          LONGITUDE: 134° 38.8' W (-134.64586)


The bench mark is a disk set flush in a rock outcrop on the west side of a
low-lying saddle between the point on the east side of the entrance to Port
Alexander locally known as "the point" and a small rocky headland with trees and
shrubs, 74.70 m (245.1 ft) east of the center of the concrete pad supporting the
Earth Scope plate tectonic GPS station antenna, 25.30 m (83.0 ft) SW of the
point on the east side of the entrance to Port Alexander locally known as "the
point", and 12.05 m (39.5 ft) NNE of the north end of the small 7.00 m by 23.00
m (23.0 ft by 75.5 ft) headland with trees and shrubs just south of "the point".



                         BENCH MARK STAMPING:  1054 F 2007
                         DESIGNATION:          945 1054 F

MONUMENTATION:           Bench Mark disk                       VM#:        18477
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Rock outcrop                          OPUS PID:        
LATITUDE:   56° 14.7' N (  56.24419)          LONGITUDE: 134° 38.8' W (-134.64614)


The bench mark is a disk set flush in a rock outcrop on the east side of the
entrance to Port Alexander, 100.91 m (331.1 ft) SSW of bench mark 945 1054 H,
84.17 m (276.1 ft) ENE of bench mark 945 1054 G, 79.25 m (260.0 ft) ENE of bench
mark 945 1054 E, and 1.00 m (3.3 ft) above the approximate high water line.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  8

                                                                                
Station ID: 9451054                         PUBLICATION DATE:  09/19/2018
Name:       PORT ALEXANDER, BARANOF ISLAND                    
            AK
NOAA Chart: 17331                           Latitude:   56° 14.8' N (  56.24670)
USGS Quad:  PORT ALEXANDER                  Longitude: 134° 38.8' W (-134.64700)


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


                         BENCH MARK STAMPING:  1054 G 2007
                         DESIGNATION:          945 1054 G

MONUMENTATION:           Tidal Station disk                    VM#:        18478
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Rock outcrop                          OPUS PID:        
LATITUDE:   56° 14.6' N (  56.24392)          LONGITUDE: 134° 38.8' W (-134.64739)


The bench mark is a disk set flush in a rock ledge on the NE corner of the
largest tree headland on the east side of the entrance to Port Alexander, 84.17
m (276.1 ft) WSW of bench mark 945 1054 F, 59.9 m (196.5 ft) NNW of a 0.90 m x
0.40 m x 0.60 m high (3.0 ft x 1.3 ft x 2.0 ft) Quartzite projection on a
prominent vein that is 4.50 m (14.8 ft) long, 5.20 m (17.1 ft) north of the
north tip of the largest treed headland on the east side of the entrance to Port
Alexander, and 1.10 m (3.6 ft) above beach level.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  6 of  8

                                                                                
Station ID: 9451054                         PUBLICATION DATE:  09/19/2018
Name:       PORT ALEXANDER, BARANOF ISLAND                    
            AK
NOAA Chart: 17331                           Latitude:   56° 14.8' N (  56.24670)
USGS Quad:  PORT ALEXANDER                  Longitude: 134° 38.8' W (-134.64700)


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


                         BENCH MARK STAMPING:  1054 H 2007
                         DESIGNATION:          945 1054 H

MONUMENTATION:           Bench Mark disk                       VM#:        18479
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Rock outcrop                          OPUS PID:        
LATITUDE:   56° 14.6' N (  56.24342)          LONGITUDE: 134° 38.8' W (-134.64692)


The bench mark is a disk set flush in a flat crevice of a rock protrusion, 100.9
m (331 ft) NNE of bench mark 945 1054 F, 62.04 m (203.5 ft) NE of the north tip
of the largest treed headland on the east side of the entrance to Port
Alexander, 59.9 m (196.5 ft) SSE of bench mark 945 1054 G, 20.30 m (66.6 ft) NNW
of the north tip a 12 m (39 ft) high rocky spire which is the tallest bare
headland on the east side of the entrance to Port Alexander, 15.50 m (50.9 ft)
east of a 0.90 m x 0.40 m x 0.60 m high (3.0 ft x 1.3 ft x 2.0 ft) Quartzite
projection on a prominent vein that is 4.50 m (14.8 ft) long, and 1.00 m (3.3
ft) above beach level.



                         BENCH MARK STAMPING:  945 1054 J 2014
                         DESIGNATION:          945 1054 J

MONUMENTATION:           Bench Mark disk                       VM#:        21194
AGENCY:                  National Ocean Service                IDB PID#:        
SETTING CLASSIFICATION:  Bedrock outcrop                       OPUS PID:        
LATITUDE:   56° 14.7' N (  56.24483)          LONGITUDE: 134° 38.8' W (-134.64742)


The bench mark is a disk set in a bedrock outcrop, 36.95 m (121.2 ft) SW of the
green tsunami GPS antenna, 28.5 m (93.5 ft) W of the direct way
internet/satellite antenna mast near four solar panels, 2 m (6.6 ft) S of the N
face of a rock outcrop and 1.5 m (4.9 ft) above the wave cut platform.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  7 of  8

                                                                                
Station ID: 9451054                         PUBLICATION DATE:  09/19/2018
Name:       PORT ALEXANDER, BARANOF ISLAND                    
            AK
NOAA Chart: 17331                           Latitude:   56° 14.8' N (  56.24670)
USGS Quad:  PORT ALEXANDER                  Longitude: 134° 38.8' W (-134.64700)


                            T I D A L   D A T U M S 


Tidal datums at PORT ALEXANDER, BARANOF ISLAND based on:

     LENGTH OF SERIES:      9 YEARS
     TIME PERIOD:           9/07-8/08, 6/09-5/17
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  9451600 SITKA, BARANOF ISLAND, SITKA SOUND


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

     HIGHEST OBSERVED WATER LEVEL (12/23/2007)         =  4.550
     MEAN HIGHER HIGH WATER                     MHHW   =  3.329
     MEAN HIGH WATER                            MHW    =  3.070
     MEAN TIDE LEVEL                            MTL    =  1.755
     MEAN SEA LEVEL                             MSL    =  1.747
     MEAN LOW WATER                             MLW    =  0.440
     North American Vertical Datum              NAVD88 =  0.358
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (12/14/2008)         = -1.307

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     945 1054  TIDAL 1                           5.001    1.931
     1054 A 2007                                 5.515    2.445
     1054 B 2007                                 3.685    0.615
     1054 C 2007                                 3.786    0.716
     1054 D 2007                                 9.053    5.983
     1054 E 2007                                 5.675    2.605
     1054 F 2007                                 4.200    1.130
     1054 G 2007                                 4.394    1.324
     1054 H 2007                                 5.007    1.937
     945 1054 J 2014                             4.417    1.347


                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  8 of  8

                                                                                
Station ID: 9451054                         PUBLICATION DATE:  09/19/2018
Name:       PORT ALEXANDER, BARANOF ISLAND                    
            AK
NOAA Chart: 17331                           Latitude:   56° 14.8' N (  56.24670)
USGS Quad:  PORT ALEXANDER                  Longitude: 134° 38.8' W (-134.64700)


                             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.

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Products available at 9451054 Port Alexander, AK

Revised: 08/08/2018
NOAA / National Ocean Service
Web site owner: Center for Operational Oceanographic Products and Services