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Bench Mark Sheet for 8419870, Seavey Island ME

Superseded Epoch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Small blue map location marker Unpublished bench mark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  7

                                                                                
Station ID: 8419870                         PUBLICATION DATE:  08/23/2016
Name:       SEAVEY ISLAND, PORTSMOUTH HARBOR                  
            ME
NOAA Chart: 13283                           Latitude:   43°  4.8' N (  43.08000)
USGS Quad:  KITTERY                         Longitude:  70° 44.5' W ( -70.74170)


To reach the tidal bench marks from Interstate 95 heading north, take Exit 1
(State Highway 103) which is 1.0 km (0.6 mi) north of the Maine state line, and
continue on State Highway 103 for 2.3 km (1.4 mi) to the main gate of Portsmouth
Naval Shipyard. The bench marks are located on the shipyard compound. The tide
gage and staff are located at Berth 2.  A security clearance is required to
enter Berth 2.


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


                 PRIMARY BENCH MARK STAMPING:  NO 21 1975
                         DESIGNATION:          841 9870 TIDAL 2

MONUMENTATION:           Tidal Station disk                    VM#:         1982
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Concrete sea wall                     OPUS PID:        
LATITUDE:   43°  4.8' N (  43.08000)          LONGITUDE:  70° 44.5' W ( -70.74170)


The primary bench mark is a disk set flush in the top of a concrete bulkhead in
the NE corner of a concrete and granite seawall at Berth 2, 23.07 m (75.7 ft) SW
of the SW corner of a one story building No. TB-63, and 0.91 m (3.0 ft) NW of
the intersection of the granite and concrete bulkhead.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  7

                                                                                
Station ID: 8419870                         PUBLICATION DATE:  08/23/2016
Name:       SEAVEY ISLAND, PORTSMOUTH HARBOR                  
            ME
NOAA Chart: 13283                           Latitude:   43°  4.8' N (  43.08000)
USGS Quad:  KITTERY                         Longitude:  70° 44.5' W ( -70.74170)


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


                         BENCH MARK STAMPING:  5 1928
                         DESIGNATION:          TIDAL 5 STA 92

MONUMENTATION:           Tidal Station disk                    VM#:         1974
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  OC0514
SETTING CLASSIFICATION:  Water table                           OPUS PID:        
LATITUDE:   43°  4.8' N (  43.08000)          LONGITUDE:  70° 44.5' W ( -70.74170)


The bench mark is a disk set in the top horizontal face of the water table
located on the south face of Building No. 2, 29 m (95 ft) NNW of the NW corner
of Building No. 115, 14.26 m (46.8 ft) east of the SW corner of Building No.
155, 1.68 m (5.5 ft) west of the SE corner of Building No. 2, and 0.58 m (1.9
ft) above the pavement.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  7

                                                                                
Station ID: 8419870                         PUBLICATION DATE:  08/23/2016
Name:       SEAVEY ISLAND, PORTSMOUTH HARBOR                  
            ME
NOAA Chart: 13283                           Latitude:   43°  4.8' N (  43.08000)
USGS Quad:  KITTERY                         Longitude:  70° 44.5' W ( -70.74170)


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


                         BENCH MARK STAMPING:  7 1940
                         DESIGNATION:          TIDAL 7 STA 92

MONUMENTATION:           Tidal Station disk                    VM#:         1976
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  OC0516
SETTING CLASSIFICATION:  Concrete monolith                     OPUS PID:        
LATITUDE:   43°  4.9' N (  43.08170)          LONGITUDE:  70° 44.4' W ( -70.74000)


The bench mark is a disk set in the top face of a concrete monolith on the east
side of the SE corner of the new addition to Building No. 92, 31.85 m (104.5 ft)
east of the SW corner of the new addition to Building No. 92, 22.74 m (74.6 ft)
NW of the most northeasterly point of Dry Dock No. 1, 5.58 m (18.3 ft) south of
the most southerly track of railroad tracks leading to the new addition of
Building No. 92, and 0.64 m (2.1 ft) above the ground.  Note: Cement on the
corner of the building is beginning to chip away and may soon affect the mark's
stability.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  7

                                                                                
Station ID: 8419870                         PUBLICATION DATE:  08/23/2016
Name:       SEAVEY ISLAND, PORTSMOUTH HARBOR                  
            ME
NOAA Chart: 13283                           Latitude:   43°  4.8' N (  43.08000)
USGS Quad:  KITTERY                         Longitude:  70° 44.5' W ( -70.74170)


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


                         BENCH MARK STAMPING:  8 1940
                         DESIGNATION:          TIDAL 8 STA 92

MONUMENTATION:           Tidal Station disk                    VM#:         1977
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  OC0517
SETTING CLASSIFICATION:  Concrete monolith                     OPUS PID:        
LATITUDE:   43°  4.9' N (  43.08170)          LONGITUDE:  70° 44.5' W ( -70.74170)


The bench mark is a disk set in the top face of a concrete monolith on the west
side of the new addition to Building No. 92, 12 m (40 ft) north of the SW corner
of the building, 9.32 m (30.6 ft) SSW of a yellow fire hydrant, 3.47 m (11.4 ft)
east of the most westerly brick face of the new addition to Building No. 92, and
0.58 m (1.9 ft) above the parking lot.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  7

                                                                                
Station ID: 8419870                         PUBLICATION DATE:  08/23/2016
Name:       SEAVEY ISLAND, PORTSMOUTH HARBOR                  
            ME
NOAA Chart: 13283                           Latitude:   43°  4.8' N (  43.08000)
USGS Quad:  KITTERY                         Longitude:  70° 44.5' W ( -70.74170)


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


                         BENCH MARK STAMPING:   
                         DESIGNATION:          13
                         ALIAS:                NAVY 13, NO STAMPING 3

MONUMENTATION:           Chiseled Square                       VM#:         1985
AGENCY:                  US Navy (USN)                         IDB PID#:  OC0518
SETTING CLASSIFICATION:  Granite water table                   OPUS PID:        
LATITUDE:   43°  4.8' N (  43.08000)          LONGITUDE:  70° 44.5' W ( -70.74170)


The bench mark is cut away corner of the granite water table located at the NE
corner of Building No. 89, 15.76 m (51.7 ft) SE of the NW corner of Building No.
115, 15.30 m (50.2 ft) SE of the NW corner of Building No. 89, 5.33 m (17.5 ft)
south of the SE corner of Building No. 115, and 0.21 m (0.7 ft) above the
ground.  NOTE:  Bench mark historically referred to as NAVY 13, AKA NO STAMPING
3.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  6 of  7

                                                                                
Station ID: 8419870                         PUBLICATION DATE:  08/23/2016
Name:       SEAVEY ISLAND, PORTSMOUTH HARBOR                  
            ME
NOAA Chart: 13283                           Latitude:   43°  4.8' N (  43.08000)
USGS Quad:  KITTERY                         Longitude:  70° 44.5' W ( -70.74170)


                            T I D A L   D A T U M S 


Tidal datums at SEAVEY ISLAND, PORTSMOUTH HARBOR based on:

     LENGTH OF SERIES:      1 YEAR
     TIME PERIOD:           November 2000 - October 2001
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8418150 PORTLAND, CASCO BAY


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

     HIGHEST OBSERVED WATER LEVEL (02/07/1978)         =  3.815
     MEAN HIGHER HIGH WATER                     MHHW   =  2.694
     MEAN HIGH WATER                            MHW    =  2.569
     North American Vertical Datum              NAVD88 =  1.409
     MEAN SEA LEVEL                             MSL    =  1.351
     MEAN TIDE LEVEL                            MTL    =  1.333
     MEAN LOW WATER                             MLW    =  0.098
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (11/30/1955)         = -1.022

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     NO 21 1975                                  3.873    1.304
     5 1928                                      7.290    4.721
     7 1940                                      5.225    2.656
     8 1940                                      5.241    2.672
     13                                          5.371    2.802


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

                                                                                
Station ID: 8419870                         PUBLICATION DATE:  08/23/2016
Name:       SEAVEY ISLAND, PORTSMOUTH HARBOR                  
            ME
NOAA Chart: 13283                           Latitude:   43°  4.8' N (  43.08000)
USGS Quad:  KITTERY                         Longitude:  70° 44.5' W ( -70.74170)


                             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 8419870 Seavey Island, ME

Revised: 08/08/2018
NOAA / National Ocean Service
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