U.S. DEPARTMENT OF COMMERCE
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National Ocean Service
Datums Page Page 1 of 6
Station ID: 8461392 PUBLICATION DATE: 04/29/2003
Name: NORWICH, THAMES RIVER
CT
NOAA Chart: 12372 Latitude: 41° 31.4' N ( 41.52330)
USGS Quad: Norwich Longitude: 72° 4.7' W ( -72.07830)
To reach the tidal bench marks from the intersection of Shetucket and Market
Streets on the south side of Norwich, turn into the parking lot of the city park
and town dock. The bench marks are along Shetucket, West Main, and Thames
Streets. The tide gage and staff were located at the SE corner of the town
dock.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 2 1967
DESIGNATION: 846 1392 TIDAL 2
MONUMENTATION: Tidal Station disk VM#: 2225
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Concrete bulkhead OPUS PID:
LATITUDE: 41° 31.4' N ( 41.52330) LONGITUDE: 72° 4.7' W ( -72.07830)
The primary bench mark is a disk set flush in the SE end of the concrete
bulkhead of the town dock, 27.55 m (90.4 ft) NW of a flagpole in the park, 5.91
m (19.4 ft) ENE of the SE corner of the town dock, and 0.82 m (2.7 ft) NNW of
the SE edge of the bulkhead.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
Station ID: 8461392 PUBLICATION DATE: 04/29/2003
Name: NORWICH, THAMES RIVER
CT
NOAA Chart: 12372 Latitude: 41° 31.4' N ( 41.52330)
USGS Quad: Norwich Longitude: 72° 4.7' W ( -72.07830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 3 1967
DESIGNATION: 846 1392 TIDAL 3
MONUMENTATION: Tidal Station disk VM#: 2226
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Concrete bulkhead OPUS PID:
LATITUDE: 41° 31.4' N ( 41.52330) LONGITUDE: 72° 4.7' W ( -72.07830)
The bench mark is a disk set flush in the NW end of the concrete bulkhead of the
town dock, 32.34 m (106.1 ft) WSW of a power pole at the intersection of
Shetucket and Market Streets, 30.51 m (100.1 ft) NNW of bench mark No 2 1967,
5.67 m (18.6 ft) ENE of the NE corner of the town dock, and 1.13 m (3.7 ft) SSE
of the NW face of the concrete base of a light pole.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
Station ID: 8461392 PUBLICATION DATE: 04/29/2003
Name: NORWICH, THAMES RIVER
CT
NOAA Chart: 12372 Latitude: 41° 31.4' N ( 41.52330)
USGS Quad: Norwich Longitude: 72° 4.7' W ( -72.07830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: W 90 1986
DESIGNATION: W 90
MONUMENTATION: Flange-encased Rod VM#: 2227
AGENCY: National Geodetic Survey (NGS) IDB PID#: LX3226
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 41° 31.4' N ( 41.52330) LONGITUDE: 72° 4.8' W ( -72.08000)
The bench mark is a flange-encased rod set in a landscaped area at the north end
of the municipal parking lot between Shetucket and Water Streets, 23.77 m (78.0
ft) SE of a sign for Slater Memorial Museum, 13 m (43 ft) NE of the east curb of
Shetucket Street, 8.11 m (26.6 ft) SE of a sign that reads Do Not Enter, 6.61 m
(21.7 ft) SW of utility pole #W222, 6.13 m (20.1 ft) SW of the west curb of
Water Street, and 0.46 m (1.5 ft) NE of a circular parking curb at the north end
of the lot. The datum point is the top of a stainless steel rod driven 2.1 m (7
ft), and encased in a 5-inch flange with logo cap.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
Station ID: 8461392 PUBLICATION DATE: 04/29/2003
Name: NORWICH, THAMES RIVER
CT
NOAA Chart: 12372 Latitude: 41° 31.4' N ( 41.52330)
USGS Quad: Norwich Longitude: 72° 4.7' W ( -72.07830)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: M 97 1986
DESIGNATION: M 97
MONUMENTATION: Flange-encased Rod VM#: 2228
AGENCY: National Geodetic Survey (NGS) IDB PID#: LX3397
SETTING CLASSIFICATION: Stainless steel rod OPUS PID#: LX3397
LATITUDE: 41° 31.2' N ( 41.52000) LONGITUDE: 72° 4.8' W ( -72.08000)
The bench mark is a flange-encased rod set in the grass median between the
sidewalk and the parking lot at the entrance to Norwich Police Department on
Thames Street, 13.17 m (43.2 ft) north of power pole #T113, 7.38 m (24.2 ft) NE
of the centerline of Thames Street, 5.49 m (18.0 ft) NNE of the centerline of
the entrance drive to the police station, and 1.01 m (3.3 ft) NE of the NE curb
of the sidewalk. The datum point is the top of a stainless steel rod driven 3.4
m (11 ft), and encased in a 5-inch flange with logo cap.
BENCH MARK STAMPING: 1392 A 1989
DESIGNATION: 846 1392 A
MONUMENTATION: Tidal Station disk VM#: 2229
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete abutment OPUS PID:
LATITUDE: 41° 31.4' N ( 41.52330) LONGITUDE: 72° 4.7' W ( -72.07830)
The bench mark is a disk set flush in the SE corner of the NE concrete abutment
for the West Main Street bridge over the Connecticut-Vermont Railroad tracks
which run parallel to Thames Street, ENE of the intersection of West Main and
Thames Streets, 46 m (152 ft) WSW of the west wall of the law offices at No. 74
West Main Street, 5 m (16 ft) SSE of the south curb of West Main Street, and
1.13 m (3.7 ft) ENE of the SW face of the abutment.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
Station ID: 8461392 PUBLICATION DATE: 04/29/2003
Name: NORWICH, THAMES RIVER
CT
NOAA Chart: 12372 Latitude: 41° 31.4' N ( 41.52330)
USGS Quad: Norwich Longitude: 72° 4.7' W ( -72.07830)
T I D A L D A T U M S
Tidal datums at NORWICH, THAMES RIVER based on:
LENGTH OF SERIES: 4 MONTHS
TIME PERIOD: July 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 = 1.092
MEAN HIGH WATER MHW = 0.994
North American Vertical Datum NAVD88 = 0.603
MEAN SEA LEVEL MSL = 0.568
MEAN TIDE LEVEL MTL = 0.533
MEAN LOW WATER MLW = 0.071
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
NO 2 1967 2.091 1.097
NO 3 1967 2.087 1.093
W 90 1986 5.280 4.286
M 97 1986 9.759 8.765
1392 A 1989 5.914 4.920
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
Station ID: 8461392 PUBLICATION DATE: 04/29/2003
Name: NORWICH, THAMES RIVER
CT
NOAA Chart: 12372 Latitude: 41° 31.4' N ( 41.52330)
USGS Quad: Norwich Longitude: 72° 4.7' W ( -72.07830)
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.