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National Ocean Service
Datums Page Page 1 of 5
Station ID: 8463827 PUBLICATION DATE: 05/15/2003
Name: MAROMAS, CONNECTICUT RIVER
CT
NOAA Chart: 12377 Latitude: 41° 32.5' N ( 41.54170)
USGS Quad: Middle Haddam Longitude: 72° 33.1' W ( -72.55170)
To reach the tidal bench marks from gate #7 of the Pratt and Whitney Plant in
Maromas, proceed east on Road C for 0.6 km (0.4 mi) to the Pratt and Whitney
pier. The bench marks are near the pier and north along four large pipes. The
tide gage and staff were 15 m (50 ft) south of the pier.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 3827 A 1987
DESIGNATION: 846 3827 A
MONUMENTATION: Tidal Station disk VM#: 2243
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete abutment OPUS PID:
LATITUDE: 41° 32.5' N ( 41.54170) LONGITUDE: 72° 33.2' W ( -72.55330)
The primary bench mark is a disk set flush in top of a concrete abutment on the
north side of the Pratt and Whitney pier, 78 m (255 ft) SE of the gate to the
pier area, 5.33 m (17.5 ft) north of the centerline of the pier, and 0.15 m (0.5
ft) south of the north end of the abutment.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8463827 PUBLICATION DATE: 05/15/2003
Name: MAROMAS, CONNECTICUT RIVER
CT
NOAA Chart: 12377 Latitude: 41° 32.5' N ( 41.54170)
USGS Quad: Middle Haddam Longitude: 72° 33.1' W ( -72.55170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: J 16 1935
DESIGNATION: J 16
MONUMENTATION: Bench Mark disk VM#: 2242
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: LX0578
SETTING CLASSIFICATION: Bridge abutment OPUS PID:
LATITUDE: 41° 31.5' N ( 41.52500) LONGITUDE: 72° 33.6' W ( -72.56000)
The bench mark is a disk set in the SW railroad bridge abutment at Bridge #23.29
over a small stream south of the Pratt and Whitney plant, 9.45 m (31.0 ft) south
of the granite south face of the north abutment, 2.53 m (8.3 ft) west of the
west track, 0.49 m (1.6 ft) north of the south upper face of the concrete SW
abutment, and 1.22 m (4.0 ft) below track grade at the level of the bottom
bridge steel plate girders.
BENCH MARK STAMPING: 3827 B 1987
DESIGNATION: 846 3827 B
MONUMENTATION: Tidal Station disk VM#: 2244
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete base OPUS PID:
LATITUDE: 41° 32.5' N ( 41.54170) LONGITUDE: 72° 33.2' W ( -72.55330)
The bench mark is a disk set in the NE corner of a 1.74 m x 2.56 m (5.7 ft x 8.4
ft) concrete platform supporting four large pipes, NW along the pipeline from
bench mark 3827 A 1987, 15 m (49 ft) west of the west railroad track, 8.66 m
(28.4 ft) east of power pole #40, 8.32 m (27.3 ft) north of a drainage ditch,
and 1.01 m (3.3 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8463827 PUBLICATION DATE: 05/15/2003
Name: MAROMAS, CONNECTICUT RIVER
CT
NOAA Chart: 12377 Latitude: 41° 32.5' N ( 41.54170)
USGS Quad: Middle Haddam Longitude: 72° 33.1' W ( -72.55170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 3827 C 1987
DESIGNATION: 846 3827 C
MONUMENTATION: Tidal Station disk VM#: 2245
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete platform OPUS PID:
LATITUDE: 41° 32.5' N ( 41.54170) LONGITUDE: 72° 33.2' W ( -72.55330)
The bench mark is a disk set in the top of a concrete platform supporting four
large pipes, 41.88 m (137.4 ft) south of the point where the pipes go
underground, 32.92 m (108.0 ft) west of the west railroad track, 3.93 m (12.9
ft) east of power pole #57, and 0.55 m (1.8 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8463827 PUBLICATION DATE: 05/15/2003
Name: MAROMAS, CONNECTICUT RIVER
CT
NOAA Chart: 12377 Latitude: 41° 32.5' N ( 41.54170)
USGS Quad: Middle Haddam Longitude: 72° 33.1' W ( -72.55170)
T I D A L D A T U M S
Tidal datums at MAROMAS, CONNECTICUT RIVER based on:
LENGTH OF SERIES: 4 MONTHS
TIME PERIOD: June 1987 - September 1987
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 = 0.840
MEAN HIGH WATER MHW = 0.766
MEAN SEA LEVEL MSL = 0.404
MEAN TIDE LEVEL MTL = 0.399
MEAN LOW WATER MLW = 0.031
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
3827 A 1987 7.589 6.823
J 16 1935 5.208 4.442
3827 B 1987 9.990 9.224
3827 C 1987 10.508 9.742
Foot Notes:
Bench mark J 16 1935 is based on one differential leveling connection and does
not meet the quality control standards of the NOS. Therefore, caution should be
used when deriving elevations for this mark.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8463827 PUBLICATION DATE: 05/15/2003
Name: MAROMAS, CONNECTICUT RIVER
CT
NOAA Chart: 12377 Latitude: 41° 32.5' N ( 41.54170)
USGS Quad: Middle Haddam Longitude: 72° 33.1' W ( -72.55170)
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.