U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 7
PUBLICATION DATE: 12/20/1984
Station ID: 8418150 SUPERCEDED DATE: 04/21/2003
Name: PORTLAND, CASCO BAY
MAINE
NOAA Chart: 13292 Latitude: 43° 39.4' N
USGS Quad: PORTLAND EAST Longitude: 70° 14.8' W
To reach the tidal bench marks from north bound Interstate 295 in Portland take
the Waterfront Exit (Alt. U.S. 1) to Commercial Street, then continue NE along
Commercial Street for 1.5 miles (2.4 km) to the Maine State Pier, the last pier-
warehouse along the waterfront. The bench marks are located within 1 mile (1.6
km) radius of tide station. The tide gage is located in the south corner on the
off shore end of the Maine State Pier.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: ELEV 14.501 FT. TIDAL 31
MONUMENTATION: Survey Disk VM#: 173
AGENCY: PID#: OC0005
SETTING CLASSIFICATION: Stone Foundation
The bench mark is located at the intersection of Commercial Street and India
Street, 206 feet (63 m) SW of the SW curb of India Street and 9 feet (3 m) NW of
the NW curb of Commercial Street. The bench mark is set vertically in the NE
face of stone foundation of two story building, 0.5 feet (0.2 m) above sidewalk.
BENCH MARK STAMPING: 38 1919
MONUMENTATION: Survey Disk VM#: 174
AGENCY: PID#: OC0011
SETTING CLASSIFICATION: Stone Slab
The bench mark is located in the NE side of the City Hall, 56.5 feet (17.2 m) NE
of NE curb of Chestnut Street, 27 feet (8 m) NW of NW curb of Congress Street,
and 3.5 feet (1.1 m) NE of the NE face of the building wing. The bench is set
in top of stone shelf, 4 feet (1 m) above the level of the sidewalk.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 7
PUBLICATION DATE: 12/20/1984
Station ID: 8418150 SUPERCEDED DATE: 04/21/2003
Name: PORTLAND, CASCO BAY
MAINE
NOAA Chart: 13292 Latitude: 43° 39.4' N
USGS Quad: PORTLAND EAST Longitude: 70° 14.8' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 3 1971
MONUMENTATION: Survey Disk VM#: 175
AGENCY: PID#: AJ2726
SETTING CLASSIFICATION: Granite Seawall
The bench mark is located adjacent to the NW corner of the Maine State Pier,
53.0 feet (16.2 m) north of corner formed by wharf and seawall intersection,
19.9 feet (6.1 m) south of a corner formed by edge of seawall and a projection
out from the seawall and 10.3 feet (3.1 m) east of galvanized parking lot
barrier. The bench mark is set flush in horizontal surface of the granite
seawall.
BENCH MARK STAMPING: NO 43 1975
MONUMENTATION: Survey Disk VM#: 176
AGENCY: PID:
SETTING CLASSIFICATION: Granite Step
The bench mark is located at the SE entrance of stairs leading to the basement
of Cumberland Country Court House, 69.0 feet (21.0 m) NE of the NE corner of
Pearl Street and Federal Street, 39.9 feet (12.2 m) north of centerline of Pearl
Street and 2.5 feet (0.8 m) south of south wall of Court House. The bench mark
is set flush in lower granite step.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 7
PUBLICATION DATE: 12/20/1984
Station ID: 8418150 SUPERCEDED DATE: 04/21/2003
Name: PORTLAND, CASCO BAY
MAINE
NOAA Chart: 13292 Latitude: 43° 39.4' N
USGS Quad: PORTLAND EAST Longitude: 70° 14.8' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 8150 A 1978
MONUMENTATION: Survey Disk VM#: 177
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Pad
The bench mark is located in the vicinity of SW corner of Maine State Pier, 39.8
feet (12.1 m) west of the SW corner of warehouse, 15 feet (5 m) south of south
edge of asphalt parking lot, 10 feet (3 m) east of north rail switch for tracks
on south side of pier, and 5.4 feet (1.6 m) north of north rail of tracks
running along the south side of the pier. The bench mark is set flush in
concrete loading pad.
BENCH MARK STAMPING: 841-8150 B 1979
MONUMENTATION: Survey Disk VM#: 178
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is located in the vicinity of intersection of Commercial Street
and India Street, on the south side of parking lot of Maine State Pier, 18 feet
(6 m) east of the west end foundation of pumping station, 12.9 feet (3.9 m)
north of south edge of foundation and 0.5 feet (0.2 m) from the south edge of
foundation. The bench mark is set flush in the concrete foundation.
BENCH MARK STAMPING: 841-8150 C 1979
MONUMENTATION: Survey Disk VM#: 179
AGENCY: PID:
SETTING CLASSIFICATION: Granite Step
The bench mark is located on Pearl Street between Middle Street and Moulton
Street at the doorway leading to the Burbomk, Douglass & Co. Building and 32
feet (10 m) north of centerline of Pearl Street. The bench mark is set in
granite step 0.1 feet (0.1 m) above ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 7
PUBLICATION DATE: 12/20/1984
Station ID: 8418150 SUPERCEDED DATE: 04/21/2003
Name: PORTLAND, CASCO BAY
MAINE
NOAA Chart: 13292 Latitude: 43° 39.4' N
USGS Quad: PORTLAND EAST Longitude: 70° 14.8' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 8150 D 1982
MONUMENTATION: Survey Disk VM#: 180
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Wall
The bench mark is located along Commercial Street in the vicinity of Grand Trunk
Railway Offices, 78.2 feet (23.8 m) NE of a fire hydrant 13.7 feet (4.2 m) SE of
centerline of railroad track leading into the garage, 13.4 feet (4.1 m) SW of
the SW corner of Garage NO. 1, and 12.0 feet (3.7 m) NW of centerline of the
road leading through the yard. The bench mark is set flush in the concrete
wall.
BENCH MARK STAMPING: NO STAMPING 1
MONUMENTATION: Drill Hole VM#: 181
AGENCY: PID#: OC0003
SETTING CLASSIFICATION: Water Table Sill
The bench mark is located at the intersection of Commercial Street and Pearl
Street, on the NE side of entrance to U.S. Custom House, 55.5 feet (16.9 m) NE
of the NE curb of Pearl Street, 11.5 feet (3.5 m) NW of the NW curb of Commer-
cial Street, and 6.5 feet (2.0 m) NE of center of entrance. The bench mark is a
0.5 inch drill hole in the sill about 1 foot (0.3 m) above sidewalk. Note: Bench
Mark historically referred to as NO 2 USE (1901).
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 7
PUBLICATION DATE: 12/20/1984
Station ID: 8418150 SUPERCEDED DATE: 04/21/2003
Name: PORTLAND, CASCO BAY
MAINE
NOAA Chart: 13292 Latitude: 43° 39.4' N
USGS Quad: PORTLAND EAST Longitude: 70° 14.8' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO STAMPING 2
MONUMENTATION: Chiseled Cross VM#: 182
AGENCY: PID#: OC0006
SETTING CLASSIFICATION: Stone Sill
The bench mark is located at the intersection of Commercial Street and India
Street on the SE corner of three story Grand Trunk Office Building, 25 feet (8
m) NE of the NE curb of India Street, 18 feet (5 m) NW of NW rail of NW one of a
group of railroad tracks and in line with extended centerline of Commercial
Street. The bench mark is a 1-inch chiseled cross in top of stone sill. Note:
Bench Mark historically referred to as NO. 30 (1910).
BENCH MARK STAMPING: NO STAMPING 3
MONUMENTATION: Chiseled Cross VM#: 183
AGENCY: PID#: OC0004
SETTING CLASSIFICATION: Stone Window Sill
The bench mark is located at 19 Commercial Street 115 feet (35 m) NE of the NE
curb of the Pearl Street, 16 feet (5 m) SW of east corner of the building, 15
feet (5 m) west of fire hydrant, and 9.5 feet (2.9 m) NW of the NW curb of
Commercial Street. The bench mark is a 1-inch chiseled cross in top of lower
stone window sill. Note: Bench Mark historically referred to as NO. 33 (1910).
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 7
PUBLICATION DATE: 12/20/1984
Station ID: 8418150 SUPERCEDED DATE: 04/21/2003
Name: PORTLAND, CASCO BAY
MAINE
NOAA Chart: 13292 Latitude: 43° 39.4' N
USGS Quad: PORTLAND EAST Longitude: 70° 14.8' W
T I D A L D A T U M S
Tidal datums at PORTLAND, CASCO BAY based on:
LENGTH OF SERIES: 19 YEARS
TIME PERIOD: 1960-1978
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION:
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (02/07/1978) = 14.17
MEAN HIGHER HIGH WATER MHHW = 9.91
MEAN HIGH WATER MHW = 9.45
MEAN TIDE LEVEL MTL = 4.90
* NATIONAL GEODETIC VERTICAL DATUM NGVD29 = 4.57
MEAN LOW WATER MLW = 0.34
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (11/30/1955) = -3.41
* NGVD reference based on adjustment of 1967 and NOS levels of 1983.
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
ELEV 14.501 FT. TIDAL 31 19.07 9.62
38 1919 74.24 64.79
NO 3 1971 15.61 6.16
NO 43 1975 58.19 48.74
8150 A 1978 16.20 6.75
841-8150 B 1979 16.97 7.52
841-8150 C 1979 40.47 31.02
8150 D 1982 18.52 9.07
NO STAMPING 1 18.62 9.17
NO STAMPING 2 19.03 9.58
NO STAMPING 3 17.46 8.01
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 7
PUBLICATION DATE: 12/20/1984
Station ID: 8418150 SUPERCEDED DATE: 04/21/2003
Name: PORTLAND, CASCO BAY
MAINE
NOAA Chart: 13292 Latitude: 43° 39.4' N
USGS Quad: PORTLAND EAST Longitude: 70° 14.8' W
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 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.