Superseded Bench Mark Sheet for 8510719, Silver Eel Pond NY

Present Epoch

Printable version

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  5

                                                   PUBLICATION DATE:  01/17/1992
Station ID: 8510719                                SUPERCEDED DATE:   04/21/2003
Name:       FISHERS ISLAND, SILVER EEL COVE                   
            NEW YORK
NOAA Chart: 13214                                  Latitude:         41° 15.4' N
USGS Quad:  NEW LONDON                             Longitude:        72°  1.9' W


To reach the tidal bench marks from Fishers Island Ferry dock on Fishers Island,
proceed off the ferry and turn right into the U.S. Coast Guard Fishers Island
Station.  The bench marks are along the harbor perimeter and out toward the
airport.  The tide gauge and staff were in the west corner of the harbor on the
U.S. Coast Guard bulkhead.


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


                 PRIMARY BENCH MARK STAMPING:  BM 1 1961

MONUMENTATION:           Survey Disk                               VM#:    11245
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Slab


The primary bench mark is set in the center of a 10 foot (3 m) square concrete
slab near the intersection of the stone jetty and the shoreline, 197 feet (60 m)
north of Bench Mark NO STAMPING 1, 134.3 feet (40.9 m) NW of the NE corner a of
U.S. Coast Guard bulkhead at the harbor entrance, and 7.1 feet (2.2 m) south of
the north corner of the concrete slab.



                         BENCH MARK STAMPING:  BM 2 1961

MONUMENTATION:           Survey Disk                               VM#:    11246
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Slab


The bench mark is set in a concrete slab in the center of a traffic island for
ferry truck scales at the foot of the Fishers Island Ferry dock, near the ferry
office building, 176 feet        (54 m) NE of the northern end of School Road,
57.4 feet (17.5 m) SW of the main vehicle loading ramp, 54.5 feet (16.6 m) south
of the western gate post to the U.S. Coast Guard facility, 32.0 feet (9.8 m)
north of the west corner of the ferry office building, 8.4 feet (2.6 m) NW of
the north curb of the truck scales, and 7.5 feet (2.3 m) NE of a manhole cover
in the center of the traffic island.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  5

                                                   PUBLICATION DATE:  01/17/1992
Station ID: 8510719                                SUPERCEDED DATE:   04/21/2003
Name:       FISHERS ISLAND, SILVER EEL COVE                   
            NEW YORK
NOAA Chart: 13214                                  Latitude:         41° 15.4' N
USGS Quad:  NEW LONDON                             Longitude:        72°  1.9' W


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


                         BENCH MARK STAMPING:  NO STAMPING 1

MONUMENTATION:           Monel Rivet                               VM#:    11247
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Step


The bench mark is a monel rivet in the NW end of the bottom step on the front of
the NW wing of the old brick U.S. Coast Guard building (formerly U.S. Post
Office), 171.0 feet (52.1 m) SW of the NE corner of the U.S. Coast Guard
bulkhead at the harbor entrance, 47.6 feet (14.5 m) west of a flagpole, 11.3
feet (3.4 m) east of the north corner of the NW wing, 8.0 feet (2.4 m) north of
the center of the doorway to the NW wing, and 0.7 foot (0.2 m) above the ground
level.



                         BENCH MARK STAMPING:  NO STAMPING 2

MONUMENTATION:           Monel Rivet                               VM#:    11248
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Step


The bench mark is a monel rivet set in the north end of the bottom of an old
concrete step leading from Harbor Road to a steel sculpture on the east side of
Silver Eel Cove, on the east side of the road leading around the harbor (Harbor
Road), 142 feet (43 m) south of the intersection of Harbor and Winthrop Roads,
127 feet (39 m) NE of the NE corner of an old brick pumphouse (now a residence
on the harbor's edge), 85.4 feet (26.0 m) SE of a high section of stone
retaining wall on the north side of the road, 72.0 feet (21.9 m) SE of power
pole #306, 11.7 feet (3.6 m) west of the steel sculpture and 7.0 feet (2.1 m)
north of the south edge of the steps. NOTE:  The bench mark has been designated
2 (1943)

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  5

                                                   PUBLICATION DATE:  01/17/1992
Station ID: 8510719                                SUPERCEDED DATE:   04/21/2003
Name:       FISHERS ISLAND, SILVER EEL COVE                   
            NEW YORK
NOAA Chart: 13214                                  Latitude:         41° 15.4' N
USGS Quad:  NEW LONDON                             Longitude:        72°  1.9' W


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


                         BENCH MARK STAMPING:  NO STAMPING 3

MONUMENTATION:           Monel Rivet                               VM#:    11249
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Tower Foundation


The bench mark is a monel rivet set in the center of a 10 foot     (3 m) square
concrete foundation of an old observation tower near the entrance road to the
airport from Whistler Avenue, 146.2 feet (44.6 m) SE of the SE corner of a 20x20
foot (6x6 m) concrete block garage, 105.8 feet (32.2 m) NW of the NE corner of a
concrete block airport building, 43.3 feet (13.2 m) west of the centerline of
the entrance road to the airport, 38.5 feet (11.7 m) SW of a fire hydrant, 76.0
feet (23.2 m) west of power pole w/transformer #317 and 3 feet (1 m) above
ground.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  5

                                                   PUBLICATION DATE:  01/17/1992
Station ID: 8510719                                SUPERCEDED DATE:   04/21/2003
Name:       FISHERS ISLAND, SILVER EEL COVE                   
            NEW YORK
NOAA Chart: 13214                                  Latitude:         41° 15.4' N
USGS Quad:  NEW LONDON                             Longitude:        72°  1.9' W


                            T I D A L   D A T U M S 


Tidal datums at FISHERS ISLAND, SILVER EEL COVE based on:

     LENGTH OF SERIES:      6 MONTHS
     TIME PERIOD:           MAY - OCTOBER 1989
     TIDAL EPOCH:           1960-1978
     CONTROL TIDE STATION:  8461490 NEW LONDON, CT


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

     HIGHEST OBSERVED WATER LEVEL (10/19/1989)         =   4.59
     MEAN HIGHER HIGH WATER                     MHHW   =   2.83
     MEAN HIGH WATER                            MHW    =   2.54
     MEAN TIDE LEVEL                            MTL    =   1.36
     MEAN LOW WATER                             MLW    =   0.19
     MEAN LOWER LOW WATER                       MLLW   =   0.00
     LOWEST  OBSERVED WATER LEVEL (11/12/1989)         =  -1.19



Bench Mark Elevation Information                In FEET above:

     Stamping or Designation                    MLLW        MHW

     BM 1 1961                                   8.40      5.86
     BM 2 1961                                   8.35      5.81
     NO STAMPING 1                               8.54      6.00
     NO STAMPING 2                              11.80      9.26
     NO STAMPING 3                              22.60     20.06


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

                                                   PUBLICATION DATE:  01/17/1992
Station ID: 8510719                                SUPERCEDED DATE:   04/21/2003
Name:       FISHERS ISLAND, SILVER EEL COVE                   
            NEW YORK
NOAA Chart: 13214                                  Latitude:         41° 15.4' N
USGS Quad:  NEW LONDON                             Longitude:        72°  1.9' 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 (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 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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