U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8417177 PUBLICATION DATE: 02/27/2006
Name: HUNNIWELL POINT, KENNEBEC RIVER
ME
NOAA Chart: 13296 Latitude: 43° 45.3' N ( 43.75500)
USGS Quad: PHIPPSBURG Longitude: 69° 47.1' W ( -69.78500)
To reach the bench marks from the intersection of U.S. Route 1 and State Route
209, proceed south on State Route 209 for 25.4 km (15.8 mi) to Fort Popham. The
bench marks are located around the fort and the shoreline. The tide gage is
located at the north corner of the fishing pier.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 1 1942
DESIGNATION: 841 7177 TIDAL 1
MONUMENTATION: Tidal Station disk VM#: 17913
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 43° 45.3' N ( 43.75500) LONGITUDE: 69° 47.0' W ( -69.78330)
The bench mark is set in a rock outcrop near the NW corner of Fort Popham, 68.77
m (225.6 ft) NNE of a utility pole NO. 36, 35.30 M (1115.8 ft) north of a flag
pole, and 8.33 m (27.3 ft) east of the NE corner of the fort.
BENCH MARK STAMPING: NO 2 1942
DESIGNATION: 841 7177 TIDAL 2
MONUMENTATION: Bench Mark disk VM#: 17914
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: OB0224
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 43° 45.3' N ( 43.75500) LONGITUDE: 69° 47.0' W ( -69.78330)
The bench mark is set in a large rock outcrop near the SW corner of Fort Popham,
40.62 m (133.3 ft) west of the SW corner of the fort, 22.62 m (74.2 ft) NE of
the centerline of teh road to the fort, 19.00 m (62.3 ft) WSW of the utility
pole NO. 36, 8.38 m (37.5 ft) NNW form a metal bolt in the rock outcrop, and
5.00 m (16.4 ft) above teh surrounding ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8417177 PUBLICATION DATE: 02/27/2006
Name: HUNNIWELL POINT, KENNEBEC RIVER
ME
NOAA Chart: 13296 Latitude: 43° 45.3' N ( 43.75500)
USGS Quad: PHIPPSBURG Longitude: 69° 47.1' W ( -69.78500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING:
DESIGNATION: 841 7177 CHISLED SQUARE
MONUMENTATION: Chiseled Square VM#: 17916
AGENCY: Unknown IDB PID#:
SETTING CLASSIFICATION: Retaining walls OPUS PID:
LATITUDE: 43° 45.3' N ( 43.75500) LONGITUDE: 69° 47.1' W ( -69.78500)
The bench mark is a chiseled square at teh east end of the concrete abutment at
the base of the fishing pier, 60.62 m (198.9 ft) WNW of a flag pole in front of
Fort Popham, 25.87 m (84.9 ft) WSW of teh SSW corner of a granite slab, and 4.12
m (13.5 ft) wast of the eastern end of the pier.
BENCH MARK STAMPING: 7177 A 2005
DESIGNATION: 841 7177 A
MONUMENTATION: Tidal Station disk VM#: 17917
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 43° 45.2' N ( 43.75330) LONGITUDE: 69° 47.0' W ( -69.78330)
The bench mark is a disk set in a rock outcrop along the beach south of Fort
Popham, 23.37 m (76.7 ft) NNW of utility pole NO. 34, 17.32 m (56.8 ft) SSE of
utility pole NO. 33, and 16.22 m (53.2 ft) ENE of the pillbox/cannon mount
remnants.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8417177 PUBLICATION DATE: 02/27/2006
Name: HUNNIWELL POINT, KENNEBEC RIVER
ME
NOAA Chart: 13296 Latitude: 43° 45.3' N ( 43.75500)
USGS Quad: PHIPPSBURG Longitude: 69° 47.1' W ( -69.78500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 7177 B 2005
DESIGNATION: 841 7177 B
MONUMENTATION: Tidal Station disk VM#: 17918
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 43° 45.3' N ( 43.75500) LONGITUDE: 69° 47.1' W ( -69.78500)
The bench mark is set in a rock outcrop along the beach south of the fort, 31.79
m (104.3 ft) SSW of utility pole NO. 34, 15.44 m (50.7 ft) NE of utility pole
NO. 33, and 10.84 m (35.6 ft) east of the granite steps north of a large rock
alongside the dirt path.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8417177 PUBLICATION DATE: 02/27/2006
Name: HUNNIWELL POINT, KENNEBEC RIVER
ME
NOAA Chart: 13296 Latitude: 43° 45.3' N ( 43.75500)
USGS Quad: PHIPPSBURG Longitude: 69° 47.1' W ( -69.78500)
T I D A L D A T U M S
Tidal datums at HUNNIWELL POINT, KENNEBEC RIVER based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: August 2005 - October 2005
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8418150 PORTLAND, CASCO BAY
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 2.817
MEAN HIGH WATER MHW = 2.688
MEAN SEA LEVEL MSL = 1.399
MEAN TIDE LEVEL MTL = 1.396
MEAN LOW WATER MLW = 0.104
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 1 1942 4.523 1.835
NO 2 1942 9.898 7.210
841 7177 CHISLED SQUARE 4.212 1.524
7177 A 2005 4.571 1.883
7177 B 2005 5.522 2.834
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8417177 PUBLICATION DATE: 02/27/2006
Name: HUNNIWELL POINT, KENNEBEC RIVER
ME
NOAA Chart: 13296 Latitude: 43° 45.3' N ( 43.75500)
USGS Quad: PHIPPSBURG Longitude: 69° 47.1' W ( -69.78500)
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.