U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 7
PUBLICATION DATE: 10/09/1984
Station ID: 8638610 SUPERCEDED DATE: 04/21/2003
Name: SEWELLS POINT, HAMPTON ROADS
VIRGINIA
NOAA Chart: 12245 Latitude: 36° 56.8' N
USGS Quad: NORFOLK NORTH Longitude: 76° 19.8' W
To reach the tidal bench marks from the NOS Atlantic Marine Center at 439 West
York Street, Norfolk, proceed west on Brambleton to its intersection with
Hampton Boulevard, then north on Hampton Boulevard to the U.S. Naval Station at
Hampton Roads, turn left on Admiral Tanssig Boulevard and go 0.8 mile (1.3 km)
past gate to Pier 2. The bench marks are located on the base within a 1 mile
(1.6 km) radius of the tide station. The tide station is on the south side of
the pier, third door from the east end of the pier.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING:
MONUMENTATION: VM#: 13412
AGENCY: PID:
SETTING CLASSIFICATION:
BENCH MARK STAMPING: 6 1927
MONUMENTATION: Survey Disk VM#: 511
AGENCY: PID#: FX0093
SETTING CLASSIFICATION: Concrete Wall
The bench mark is at the intersection of Morris Street and Decatur Avenue, set
vertically in the NW corner of Building Z-130, on the north face of the builing,
1 foot (0.3 m) east of the NW corner of building, and 3.5 feet (1.1 m) above
the street level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 7
PUBLICATION DATE: 10/09/1984
Station ID: 8638610 SUPERCEDED DATE: 04/21/2003
Name: SEWELLS POINT, HAMPTON ROADS
VIRGINIA
NOAA Chart: 12245 Latitude: 36° 56.8' N
USGS Quad: NORFOLK NORTH Longitude: 76° 19.8' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 10 1917 ELEV 10.049 FT
MONUMENTATION: Survey Disk VM#: 512
AGENCY: PID#: FX0098
SETTING CLASSIFICATION: Concrete Post
The bench mark is set in a concrete post at the SE corner of Maryland Avenue and
Gilbert Street, in the NW corner of the David Adams Memorial Chapel's grounds,
53 feet (16 m) NW of the NW corner of the chapel, 13.5 feet (4.1 m) south of
south edge of the Gilbert Street sidewalk, and 11.5 feet (3.5 m) east of the
edge of the walk of Maryland Avenue, and 0.2 foot (0.1 m) below ground level.
BENCH MARK STAMPING: 9 1927
MONUMENTATION: Survey Disk VM#: 513
AGENCY: PID#: FX0101
SETTING CLASSIFICATION: Concrete Steps
The bench mark is set flush in the fourth step at the NE corner of building
Z-105 on Truxton Street, 0.5 foot (0.2 m) north of the north face of the
building, and 3 feet (1 m) above ground level.
BENCH MARK STAMPING: 16.368
MONUMENTATION: Survey Disk VM#: 514
AGENCY: PID#: FX0087
SETTING CLASSIFICATION: Concrete Monument
The bench mark is set in a 1.5 foot (0.5 m) square concrete monument in the lawn
at the SW corner of the west wing of the Administration Building of the Naval
Station, between the Administration building and the gymnasium, and 2.5 feet
(0.8 m) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 7
PUBLICATION DATE: 10/09/1984
Station ID: 8638610 SUPERCEDED DATE: 04/21/2003
Name: SEWELLS POINT, HAMPTON ROADS
VIRGINIA
NOAA Chart: 12245 Latitude: 36° 56.8' N
USGS Quad: NORFOLK NORTH Longitude: 76° 19.8' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 3 1974
MONUMENTATION: Survey Disk VM#: 515
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Cap
The bench mark is set flush in the top of a cement cap rail on the south side of
Pier 2 at the Naval Station, 32 feet (10 m) south of the south wall of the pier
building, 9.2 feet (2.8 m) west of the easternmost bollard on the south side of
the pier, 1.3 feet (0.4 m) north of the south edge of the pier, and 0.5 foot
(0.2 m) above the level of the street pavement.
BENCH MARK STAMPING: NO 4 1974
MONUMENTATION: Survey Disk VM#: 516
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Slab
The bench mark is at the intersection of Morris Street and Decatur Avenue, set
in the SW corner of a 12x15 foot (4x5 m) concrete slab, 111.0 feet (33.8 m) NW
of the NW corner of Building Z-103, 44.8 feet (13.7 m) east of the easternmost
rail which runs down the center of Decatur Avenue, 24.0 feet (7.3 m) SW of the
SW rail of tracks which pass on an arc through the intersection, 1.1 feet (0.3
m) east of the west face of slab, and 1.0 foot (0.3 m) north of the south face.
BENCH MARK STAMPING: TOWER 1 RESET 1972
MONUMENTATION: Survey Disk VM#: 517
AGENCY: PID#: FX0095
SETTING CLASSIFICATION: Concrete Step
The bench mark is set flush in a concrete step, 9.5 feet (2.9 m) north of the NW
corner of the Fleet Religious Support building, 5 feet (2 m) north of a utility
pole, 2.5 feet (0.8 m) east of a concrete bulkhead, and 1 foot (0.3 m) east of
the west end of the step.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 7
PUBLICATION DATE: 10/09/1984
Station ID: 8638610 SUPERCEDED DATE: 04/21/2003
Name: SEWELLS POINT, HAMPTON ROADS
VIRGINIA
NOAA Chart: 12245 Latitude: 36° 56.8' N
USGS Quad: NORFOLK NORTH Longitude: 76° 19.8' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: TOWER 2 RESET 1972
MONUMENTATION: Survey Disk VM#: 518
AGENCY: PID#: FX0097
SETTING CLASSIFICATION: Concrete Monument
The bench mark is set flush in a concrete monument in the vicinity of the Fleet
Religious Support Building, 46.3 feet (14.1 m) south of the SE corner of the
Fleet Religious Support Building 17.8 feet (5.4 m) south of the southern- most
rail of tracks, 11.9 feet (3.6 m) east of the NE corner of the PWC Engineering
Department Building, and 2.5 feet (0.8 m) south of light pole Z-5.
BENCH MARK STAMPING: 8610 B 1977
MONUMENTATION: Survey Disk VM#: 519
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Step
The bench mark is set flush in the third step at the main entrance of 449 Morris
Street, the headquarters U.S. Naval Station Norfolk, 64.0 feet (19.5 m) south of
the centerline of Morris Street, and 5.3 feet (1.6 m) east of the west side of
step.
BENCH MARK STAMPING: 8610 C 1979
MONUMENTATION: Survey Disk VM#: 520
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Step
The bench mark is set in the first step leading to the first floor offices on
the east end of Building Z-101, 72.2 feet (22.0 m) south of the centerline of
Morris Street, 32.2 feet (9.8 m) west of the centerline of north-south concrete
road between the buildings, 26.9 feet (8.2 m) south of the NE corner of Bulding
Z-101, and 3.5 feet (1.1 m) east of east wall.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 7
PUBLICATION DATE: 10/09/1984
Station ID: 8638610 SUPERCEDED DATE: 04/21/2003
Name: SEWELLS POINT, HAMPTON ROADS
VIRGINIA
NOAA Chart: 12245 Latitude: 36° 56.8' N
USGS Quad: NORFOLK NORTH Longitude: 76° 19.8' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 8610 D 1979
MONUMENTATION: Survey Disk VM#: 521
AGENCY: PID:
SETTING CLASSIFICATION: Manhole Foundation
The bench mark is set flush in a 6 x 9 foot (2x3 m) concrete slab surrounding
the utility manhole in the center of Maryland Avenue at the intersection of
Maryland Avenue and Morris Street, and 108 feet (33 m) north of the centerline
of East Morris Street in front of the Our Lady of Victory Chapel.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 7
PUBLICATION DATE: 10/09/1984
Station ID: 8638610 SUPERCEDED DATE: 04/21/2003
Name: SEWELLS POINT, HAMPTON ROADS
VIRGINIA
NOAA Chart: 12245 Latitude: 36° 56.8' N
USGS Quad: NORFOLK NORTH Longitude: 76° 19.8' W
T I D A L D A T U M S
Tidal datums at SEWELLS POINT, HAMPTON ROADS 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 (08/23/1933) = 8.39
MEAN HIGHER HIGH WATER MHHW = 2.80
MEAN HIGH WATER MHW = 2.59
MEAN TIDE LEVEL MTL = 1.36
* NATIONAL GEODETIC VERTICAL DATUM NGVD29 = 1.17
MEAN LOW WATER MLW = 0.12
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (01/31/1966) = -3.21
* NGVD reference based on adjustment of 1972 and NOS levels of 1984.
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
0 0.00 0.00
6 1927 13.04 10.45
NO 10 1917 ELEV 10.049 FT 10.78 8.19
9 1927 10.42 7.83
16.368 17.12 14.53
NO 3 1974 9.88 7.29
NO 4 1974 9.74 7.15
TOWER 1 RESET 1972 9.82 7.23
TOWER 2 RESET 1972 10.32 7.73
8610 B 1977 14.79 12.20
8610 C 1979 9.90 7.31
8610 D 1979 9.22 6.63
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 7
PUBLICATION DATE: 10/09/1984
Station ID: 8638610 SUPERCEDED DATE: 04/21/2003
Name: SEWELLS POINT, HAMPTON ROADS
VIRGINIA
NOAA Chart: 12245 Latitude: 36° 56.8' N
USGS Quad: NORFOLK NORTH Longitude: 76° 19.8' 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.