U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8454578 PUBLICATION DATE: 06/15/2016
Name: EAST GREENWICH, GREENWICH B.
RI
NOAA Chart: 13221 Latitude: 41° 39.9' N ( 41.66500)
USGS Quad: EAST GREENWICH Longitude: 71° 26.7' W ( -71.44500)
To reach the tide station from the US Post Office at 5775 Post Road (Route 1) in
East Greenwich, proceed 3.2 km (2.0 mi) NE on Route 1 (Post Road and then Main
Street) to the intersection with King Street, turn right and proceed 0.3 km (0.2
mi) east on King Street under the railroad tracks to the stop sign at Water
Street, turn left and proceed 0.2 km (0.1 mi) north on Water Street to Division
Street, turn left on Division Street and then immediately turn right to stay on
Division Street and proceed 0.2 km (0.1 mi) north on Division Street continuing
straight on the driveway into Nortons Marina. The tide station is on the dock
to the right. The bench marks are located along Water and Division Streets.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: ELEV 26.808 FT TIDAL 5
DESIGNATION: 845 4578 TIDAL 5
MONUMENTATION: Tidal Station disk VM#: 21446
AGENCY: US Coast & Geodetic Survey IDB PID#: LW0115
SETTING CLASSIFICATION: Stone foundation OPUS PID:
LATITUDE: 41° 39.8' N ( 41.66414) LONGITUDE: 71° 26.8' W ( -71.44589)
The primary bench mark is a disk set vertically on the E side of the SE corner
of the stone foundation of a one story brick building at 1 division street,
27.28 m (89.5 ft) SW of the SE corner of E building wing, 23.17 m (76.0 ft) S of
the inside corner of E building wing, 16.39 m (53.8 ft) NW of power pole no. 3
on S side of division street, 13.81 m (45.3 ft) W of Norton's marina sign, 1.39
m (4.6 ft) N of the SE corner of building and 0.60 m (2.0 ft) above grade.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8454578 PUBLICATION DATE: 06/15/2016
Name: EAST GREENWICH, GREENWICH B.
RI
NOAA Chart: 13221 Latitude: 41° 39.9' N ( 41.66500)
USGS Quad: EAST GREENWICH Longitude: 71° 26.7' W ( -71.44500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4578 A 2015
DESIGNATION: 845 4578 A
MONUMENTATION: Bench Mark disk VM#: 21447
AGENCY: National Ocean Service IDB PID#:
SETTING CLASSIFICATION: Concrete footing OPUS PID:
LATITUDE: 41° 39.9' N ( 41.66581) LONGITUDE: 71° 26.7' W ( -71.44575)
The bench mark is a disk set in the concrete sill on the S side of the S most
overhead door on the NE side of the marina building, 35.99 m (118.1 ft) W of
light pole with extinguisher along seawall S of dock D, 27.17 m (89.1 ft) SSE of
N most corner of marina building, 22.30 m (73.2 ft) SW of S inside corner of dry
dock channel, 16.35 m (53.6 ft) SSW of sewer manhole cover E of center overhead
door, 14.24 m (46.7 ft) NNW of the SE corner of marina building.
BENCH MARK STAMPING: 4578 B 2015
DESIGNATION: 845 4578 B
MONUMENTATION: Bench Mark disk VM#: 21448
AGENCY: National Ocean Service IDB PID#:
SETTING CLASSIFICATION: Concrete retaining wall OPUS PID#: BBDX81
LATITUDE: 41° 39.9' N ( 41.66525) LONGITUDE: 71° 26.8' W ( -71.44611)
The bench mark is a disk in the top of a concrete retaining wall set into the
embankment on the E side of railroad tracks, 15.62 m (51.2 ft) NNE of the SW
corner of the W bay yacht club, 10.57 m (34.7 ft) SE of concrete base of guy
wire supporting overhead power line structure of electric train, 9.19 m (30.2
ft) NNE of vertical steel support of overhead electric train power lines, 7.36 m
(24.1 ft) NW of the NW corner of W bay yacht club, and 3.50 m (11.5 ft) N of S
end of retaining wall.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8454578 PUBLICATION DATE: 06/15/2016
Name: EAST GREENWICH, GREENWICH B.
RI
NOAA Chart: 13221 Latitude: 41° 39.9' N ( 41.66500)
USGS Quad: EAST GREENWICH Longitude: 71° 26.7' W ( -71.44500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4578 C 2015
DESIGNATION: 845 4578 C
MONUMENTATION: Bench Mark disk VM#: 21449
AGENCY: National Ocean Service IDB PID#:
SETTING CLASSIFICATION: Concrete stair OPUS PID:
LATITUDE: 41° 39.8' N ( 41.66353) LONGITUDE: 71° 26.7' W ( -71.44536)
The bench mark is a disk set in the N end of the first step of the E Greenwich
yacht club main entrance at 10 water street, 28.85 m (94.7 ft) N of the SW
corner of building, 19.70 m (64.6 ft) S of second decorative light post on W
side of water street S of Division street, 17.19 m (56.4 ft) SSW of the NW
corner of building, 12.70 m (41.7 ft) ENE of power pole, 3.95 m (13.0 ft) E of
the centerline of water street.
BENCH MARK STAMPING: 4578 D 2015
DESIGNATION: 845 4578 D
MONUMENTATION: Bench Mark disk VM#: 21450
AGENCY: National Ocean Service IDB PID#:
SETTING CLASSIFICATION: Concrete wall OPUS PID:
LATITUDE: 41° 39.8' N ( 41.66378) LONGITUDE: 71° 26.8' W ( -71.44608)
The bench mark is a disk set flush in the top of the S end of the E of two old
concrete walls running along the railroad track embankment S of Division street,
26.26 m (86.2 ft) N of the NW corner of small shed on W side of boat storage
lot, 2.64 m (8.7 ft) ESE of S end of W of the two low walls, 2.02 m (6.6 ft) WSW
of wooden light pole on W side of boat storage lot.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8454578 PUBLICATION DATE: 06/15/2016
Name: EAST GREENWICH, GREENWICH B.
RI
NOAA Chart: 13221 Latitude: 41° 39.9' N ( 41.66500)
USGS Quad: EAST GREENWICH Longitude: 71° 26.7' W ( -71.44500)
T I D A L D A T U M S
Tidal datums at EAST GREENWICH, GREENWICH B. based on:
LENGTH OF SERIES: 5 MONTHS
TIME PERIOD: APRIL 2015 - AUGUST 2015
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8452944 CONIMICUT LIGHT, NARRAGANSETT BAY
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 1.364
MEAN HIGH WATER MHW = 1.289
North American Vertical Datum NAVD88 = 0.725
MEAN TIDE LEVEL MTL = 0.670
MEAN SEA LEVEL MSL = 0.628
MEAN LOW WATER MLW = 0.052
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
ELEV 26.808 FT TIDAL 5 8.614 7.325
4578 A 2015 2.219 0.930
4578 B 2015 5.034 3.745
4578 C 2015 3.010 1.721
4578 D 2015 5.679 4.390
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8454578 PUBLICATION DATE: 06/15/2016
Name: EAST GREENWICH, GREENWICH B.
RI
NOAA Chart: 13221 Latitude: 41° 39.9' N ( 41.66500)
USGS Quad: EAST GREENWICH Longitude: 71° 26.7' W ( -71.44500)
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.