U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  6

                                                                                
Station ID: 8511236                         PUBLICATION DATE:  02/08/2018
Name:       PLUM ISLAND  PLUM GUT HARBOR                      
            NY
NOAA Chart: 13209                           Latitude:   41° 10.3' N (  41.17170)
USGS Quad:  PLUM ISLAND                     Longitude:  72° 12.3' W ( -72.20500)


To reach the tidal bench marks from the intersection of State Roads 25 and 27 in
Greenport Long Island, proceed east on State Road 25 for 12.9 km (8.0 mi), turn
right into the USDA Animal Disease Centers facility, and take the Plum Island
employee shuttle ferry to Plum Gut Harbor.  The bench marks are within the
confines of the fenced in Harbor area; access to restricted area beyond the
guard house is not necessary.  The tide gauge station and staff were in the NE
portion of the harbor, on the short angled section of bulkhead.


                         T I D A L   B E N C H   M A R K S
                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  6

                                                                                
Station ID: 8511236                         PUBLICATION DATE:  02/08/2018
Name:       PLUM ISLAND  PLUM GUT HARBOR                      
            NY
NOAA Chart: 13209                           Latitude:   41° 10.3' N (  41.17170)
USGS Quad:  PLUM ISLAND                     Longitude:  72° 12.3' W ( -72.20500)


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


                 PRIMARY BENCH MARK STAMPING:   
                         DESIGNATION:          TIDAL 4 STA II 24
                         ALIAS:                851 1236 NO STAMPING 1

MONUMENTATION:           Rivet                                 VM#:         2284
AGENCY:                  National Geodetic Survey (NGS)        IDB PID#:  LX0271
SETTING CLASSIFICATION:  Concrete bulkhead                     OPUS PID:        
LATITUDE:   41° 10.3' N (  41.17222)          LONGITUDE:  72° 12.4' W ( -72.20639)


The primary bench mark is a 3/8-inch monel rivet set in a concrete section of
bulkhead on the west side of the harbor, 31.61 (103.7 ft) south of the NW corner
of the bulkhead for the Plum Isle ferry, 28.10 m (92.2 ft) SE of the east corner
of Feed Building, 17.68 m (58.0 ft) north of the center line of a wood pier,
1.10 m (3.6 ft) south of the north edge of the concrete bulkhead, and 0.21 m
(0.7 ft) west of the east face of the concrete bulkhead. It was designated BM 4
1943 by USC&GS.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  6

                                                                                
Station ID: 8511236                         PUBLICATION DATE:  02/08/2018
Name:       PLUM ISLAND  PLUM GUT HARBOR                      
            NY
NOAA Chart: 13209                           Latitude:   41° 10.3' N (  41.17170)
USGS Quad:  PLUM ISLAND                     Longitude:  72° 12.3' W ( -72.20500)


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


                         BENCH MARK STAMPING:  NO 7 1957
                         DESIGNATION:          TIDAL 7 STA II 24

MONUMENTATION:           Bench Mark disk                       VM#:         2280
AGENCY:                  National Geodetic Survey (NGS)        IDB PID#:  LX0268
SETTING CLASSIFICATION:  Concrete base of pipeline             OPUS PID:        
LATITUDE:   41° 10.4' N (  41.17306)          LONGITUDE:  72° 12.3' W ( -72.20472)


The bench mark is a disk set flush in the top of the SW corner of the concrete
base of a pipeline on the north side of the harbor, 41.15 m (135.0 ft) south of
the intersection of the pipeline with the fence, 16.06 m (52.7 ft) north of a
fire hydrant, 8.93 m (29.3 ft) west of a concrete retaining wall of the fuel
bunker, and 1.07 m (3.5 ft) north of the pipeline support post just north of the
road leading around the harbor.



                         BENCH MARK STAMPING:  NO 8 1961
                         DESIGNATION:          851 1236 TIDAL 8

MONUMENTATION:           Bench Mark disk                       VM#:         2281
AGENCY:                  National Geodetic Survey (NGS)        IDB PID#:        
SETTING CLASSIFICATION:  Concrete sill                         OPUS PID:        
LATITUDE:   41° 10.4' N (  41.17306)          LONGITUDE:  72° 12.3' W ( -72.20472)


The bench mark is a disk set flush in the NW end of the concrete sill of a
garage door at the guard house at Plum Gut Harbor.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  6

                                                                                
Station ID: 8511236                         PUBLICATION DATE:  02/08/2018
Name:       PLUM ISLAND  PLUM GUT HARBOR                      
            NY
NOAA Chart: 13209                           Latitude:   41° 10.3' N (  41.17170)
USGS Quad:  PLUM ISLAND                     Longitude:  72° 12.3' W ( -72.20500)


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


                         BENCH MARK STAMPING:  NO 9 1964
                         DESIGNATION:          851 1236 TIDAL 9

MONUMENTATION:           Bench Mark disk                       VM#:         2282
AGENCY:                  National Geodetic Survey (NGS)        IDB PID#:        
SETTING CLASSIFICATION:  Concrete base                         OPUS PID:        
LATITUDE:   41° 10.4' N (  41.17306)          LONGITUDE:  72° 12.3' W ( -72.20472)


The bench mark is a disk set in the NE corner of a concrete base for a steel
mooring post at the main wharf of the harbor, 47.00 (154.2 ft) south of a flag
pole, 46.94 m (154.0 ft) SE of a fuel pump riser pipe, 2.80 m (9.2 ft) NW of the
bulkhead, 0.37 m (1.2 ft) north of a steel mooring post, and 0.15 m (0.5 ft)
below the ground surface.



                         BENCH MARK STAMPING:  1236 A 1989
                         DESIGNATION:          851 1236 A 1989

MONUMENTATION:           Bench Mark disk                       VM#:         2283
AGENCY:                  National Geodetic Survey (NGS)        IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   41° 10.4' N (  41.17306)          LONGITUDE:  72° 12.3' W ( -72.20472)


The bench mark is a disk crimped to a stainless steel rod, located on the NW
side of the harbor, near the dock warehouse, 72.45 m (237.7 ft) north of the sea
wall at the center line of the loading ramp for Plum Island, 53.64 m (176.0 ft)
west of a pipeline at the point where it passes through the fence, 11.06 m (36.3
ft) east of the center line of the steps to the warehouse loading dock, 0.94 m
(3.1 ft) south of the SE corner and in line with the east face of the warehouse
building.  The bench mark is 0.03 m (0.1 ft) below the ground surface, crimped
to a stainless steel rod driven 17 m (56 ft) to refusal, and encased in a 5-inch
PVC pipe.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  6

                                                                                
Station ID: 8511236                         PUBLICATION DATE:  02/08/2018
Name:       PLUM ISLAND  PLUM GUT HARBOR                      
            NY
NOAA Chart: 13209                           Latitude:   41° 10.3' N (  41.17170)
USGS Quad:  PLUM ISLAND                     Longitude:  72° 12.3' W ( -72.20500)


                            T I D A L   D A T U M S 


Tidal datums at PLUM ISLAND  PLUM GUT HARBOR based on:

     LENGTH OF SERIES:      6 MONTHS
     TIME PERIOD:           May 1989 - October 1989
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8461490 NEW LONDON, THAMES RIVER


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

     MEAN HIGHER HIGH WATER                     MHHW   =  0.942
     MEAN HIGH WATER                            MHW    =  0.852
     North American Vertical Datum              NAVD88 =  0.591
     MEAN SEA LEVEL                             MSL    =  0.464
     MEAN TIDE LEVEL                            MTL    =  0.456
     MEAN LOW WATER                             MLW    =  0.060
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     TIDAL 4 STA II 24                           2.086    1.234
     NO 7 1957                                   2.525    1.673
     NO 8 1961                                   2.703    1.851
     NO 9 1964                                   1.973    1.121
     1236 A 1989                                 3.555    2.703


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

                                                                                
Station ID: 8511236                         PUBLICATION DATE:  02/08/2018
Name:       PLUM ISLAND  PLUM GUT HARBOR                      
            NY
NOAA Chart: 13209                           Latitude:   41° 10.3' N (  41.17170)
USGS Quad:  PLUM ISLAND                     Longitude:  72° 12.3' W ( -72.20500)


                             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.