U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 6
PUBLICATION DATE: 07/25/1985
Station ID: 8574070 SUPERCEDED DATE: 04/21/2003
Name: HAVRE DE GRACE, CHESAPEAKE BAY
MARYLAND
NOAA Chart: 12274 Latitude: 39° 32.2' N
USGS Quad: HAVRE DE GRACE Longitude: 76° 5.3' W
To reach the tidal bench marks from the junction of U.S. Highway 40 and State
Highway 7 proceed east on State Highway 7 for 0.5 mile (0.8 km) to Union Avenue,
continue south on Union Avenue for 1.0 mile (1.6 km) to Commerce Street, turn
left on Commerce Street and proceed 0.15 mile (0.24 km) to Yacht Basin Street.
The bench marks are located in the marina, city park, and along Union Avenue.
The tide station is located in the city marina.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 5 1938
MONUMENTATION: Survey Disk VM#: 419
AGENCY: PID#: JV0013
SETTING CLASSIFICATION: Concrete Step
The bench mark is set flush in the lower step on the west face of the Veterans
Monument in the city park at the city marina, 162.0 feet (49.4 m) south of the
centerline of Commerce Street, 18.0 feet (5.5 m) west of the most easterly
flagpole, 8.0 feet (2.4 m) east of the most westerly flagpole, and 1.0 foot (0.3
m) above ground level.
BENCH MARK STAMPING: 1 1927
MONUMENTATION: Survey Disk VM#: 420
AGENCY: PID#: JV0015
SETTING CLASSIFICATION: Stone Masonry Retaining Wall
The bench mark is set in the top of the stone masonry retaining wall of the
railroad bridge near the intersection of Otsego Street and Union Avenue, 106.0
feet (32.3 m) west of the east end of the wall, 51.0 feet (15.5 m) east of the
west end of the wall, 35.4 feet (10.8 m) SSW of the centerline of Otsego Street,
27.8 feet (8.5 m) WSW of power pole G&E 70627, and 3.8 feet (1.2 m) above ground
level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
PUBLICATION DATE: 07/25/1985
Station ID: 8574070 SUPERCEDED DATE: 04/21/2003
Name: HAVRE DE GRACE, CHESAPEAKE BAY
MARYLAND
NOAA Chart: 12274 Latitude: 39° 32.2' N
USGS Quad: HAVRE DE GRACE Longitude: 76° 5.3' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 2 1927
MONUMENTATION: Survey Disk VM#: 421
AGENCY: PID#: JV0016
SETTING CLASSIFICATION: Stone Masonry Retaining Wall
The bench mark is set in the top of the stone masonry retaining wall of the
railroad tunnel near the intersection of Otsego Street and Union Avenue, 63.6
feet (19.4 m) south of the centerline of Otsego Street, 42.3 feet (12.9 m) SE of
power pole G&E 70632, 11.0 feet (3.4 m) east of the centerline of the road
through the tunnel, and 2.5 feet (0.8 m) above ground level.
BENCH MARK STAMPING: NO 4 1938
MONUMENTATION: Survey Disk VM#: 422
AGENCY: PID#: JV0011
SETTING CLASSIFICATION: Concrete Bulkhead Cap
The bench mark is set flush in the top of the concrete bulkhead cap at the Havre
de Grace City Marina, 105.3 feet (32.1 m) SW of the SW corner of the Marina
Snack Bar and Harbor Masters Office, 29.2 feet (8.9 m) NW of the utility pole
bearing inscription 400M Mercury, 26.5 feet (8.1 m) NW of the most SE corner of
the concrete bulkhead, and level with the parking area.
BENCH MARK STAMPING: 4070 A 1977
MONUMENTATION: Survey Disk VM#: 423
AGENCY: PID#: JV6256
SETTING CLASSIFICATION: Concrete Footing
The bench mark is set flush in the west concrete cap of a cellar well entrance
to an octagon-shaped gazebo in the city park, 104.4 feet (31.8 m) south of the
centerline of Commerce Street, 73.0 feet (22.3 m) NW of the NW corner of the
Veterans Monument, 25.1 feet (7.7 m) SSW of the SW face of the gazebo, and 0.2
foot (0.1 m) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
PUBLICATION DATE: 07/25/1985
Station ID: 8574070 SUPERCEDED DATE: 04/21/2003
Name: HAVRE DE GRACE, CHESAPEAKE BAY
MARYLAND
NOAA Chart: 12274 Latitude: 39° 32.2' N
USGS Quad: HAVRE DE GRACE Longitude: 76° 5.3' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4070 B 1979
MONUMENTATION: Survey Disk VM#: 424
AGENCY: PID#: JV6255
SETTING CLASSIFICATION: Stainless Steel Rod
The bench mark is located on the NE corner of the intersection of South Union
Avenue and Commerce Street, 76.8 feet (23.4 m) SW of the SW corner of a
two-story brick house, 42.9 feet (13.1 m) north of the centerline of Commerce
Street, 32.1 feet (9.8 m) east of the centerline of South Union Avenue, and 12.8
feet (3.9 m) NNW of a fire hydrant. The bench mark is 0.2 foot (0.1 m) below
ground level, crimped to a stainless steel rod driven 24 feet (7 m) to refusal,
and encased in a 4-inch PVC pipe and concrete kickblock.
BENCH MARK STAMPING: 4070 C 1979
MONUMENTATION: Survey Disk VM#: 425
AGENCY: PID#: JV6257
SETTING CLASSIFICATION: Stainless Steel Rod
The bench mark is located on the SW corner of the intersection of Revolution
Street and South Union Avenue, 124.4 feet (37.9 m) NE of the NE corner of a
parking garage, 44.5 feet (13.6 m) west of the centerline of South Union Avenue,
38.0 feet (11.6 m) south of the centerline of Revolution Street, and 13.1 feet
(4.0 m) west of a traffic signal post. The bench mark is 0.1 foot (0.03 m)
below ground level, crimped to a stainless steel rod driven 36 feet (11 m) below
ground level, and encased in a 4-inch PVC pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
PUBLICATION DATE: 07/25/1985
Station ID: 8574070 SUPERCEDED DATE: 04/21/2003
Name: HAVRE DE GRACE, CHESAPEAKE BAY
MARYLAND
NOAA Chart: 12274 Latitude: 39° 32.2' N
USGS Quad: HAVRE DE GRACE Longitude: 76° 5.3' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4070 D 1979
MONUMENTATION: Survey Disk VM#: 426
AGENCY: PID#: JV6247
SETTING CLASSIFICATION: Stainless Steel Rod
The bench mark is located on the NW corner of the intersection of South Union
Avenue and Congress Street, 66.5 feet (20.3 m) SE of the SE corner of St. Johns
Episcopalian Church, 29.5 feet (9.0 m) west of the centerline of South Union
Avenue, 29.0 feet (8.8 m) north of the centerline of Congress Street, 7.6 feet
(2.3 m) east of the east edge of the sidewalk, and 6.3 feet (1.9 m) SE of a
traffic signal post. The bench mark is 0.1 foot (0.03 m) below ground level,
crimped to a stainless steel rod driven 24 feet (7 m) to refusal, and encased in
a 4-inch PVC pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
PUBLICATION DATE: 07/25/1985
Station ID: 8574070 SUPERCEDED DATE: 04/21/2003
Name: HAVRE DE GRACE, CHESAPEAKE BAY
MARYLAND
NOAA Chart: 12274 Latitude: 39° 32.2' N
USGS Quad: HAVRE DE GRACE Longitude: 76° 5.3' W
T I D A L D A T U M S
Tidal datums at HAVRE DE GRACE, CHESAPEAKE BAY based on:
LENGTH OF SERIES: 10 YEARS
TIME PERIOD: 1972-1984
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8574680 BALTIMORE
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (09/06/1979) = 7.01
MEAN HIGHER HIGH WATER MHHW = 2.37
MEAN HIGH WATER MHW = 2.02
MEAN TIDE LEVEL MTL = 1.13
* NATIONAL GEODETIC VERTICAL DATUM NGVD29 = 0.41
MEAN LOW WATER MLW = 0.23
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (12/25/1980) = -3.96
* NGVD reference based on elevations published in Quad 390761, 1973, and NOS
leveling of 1984.
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
NO 5 1938 24.38 22.36
1 1927 24.63 22.61
2 1927 27.04 25.02
NO 4 1938 6.13 4.11
4070 A 1977 24.50 22.48
4070 B 1979 24.82 22.80
4070 C 1979 34.58 32.56
4070 D 1979 41.29 39.27
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
PUBLICATION DATE: 07/25/1985
Station ID: 8574070 SUPERCEDED DATE: 04/21/2003
Name: HAVRE DE GRACE, CHESAPEAKE BAY
MARYLAND
NOAA Chart: 12274 Latitude: 39° 32.2' N
USGS Quad: HAVRE DE GRACE Longitude: 76° 5.3' 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.