U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 6
PUBLICATION DATE: 07/20/1990
Station ID: 8637686 SUPERCEDED DATE: 04/21/2003
Name: YORKTOWN, YORK RIVER
VIRGINIA
NOAA Chart: 12241 Latitude: 37° 13.4' N
USGS Quad: POQUOSON WEST Longitude: 76° 26.4' W
To reach the tidal bench marks from the Coleman Memorial Bridge in Yorktown,
proceed south on U.S. Highway 17 for 5.6 miles (8.6 km) to State Road 173, turn
left onto State Road 173 and go 4.0 miles (6.4 km) to Yorktown Amoco Refinery on
Goodwin Neck. The bench marks are on the Yorktown Amoco Refinery property and
vicinity. The tide gage and staff were on the pier at the NE corner of the
refinery.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 1 1972
MONUMENTATION: Survey Disk VM#: 3428
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Foundation on Wood Pier
The bench mark is set flush in the top of a concrete foundation of an abandoned
crane footing on the pier at the NE corner of Yorktown Amoco Refinery, and at
the first offset pumping station on the west side of the pier.
BENCH MARK STAMPING: T 266 1942
MONUMENTATION: Survey Disk VM#: 3425
AGENCY: PID#: GV0386
SETTING CLASSIFICATION: Piling
The bench mark is set on a piling at the south bank of Back Creek at the O.R.
Mills two-and-one-half-story frame house, 0.6 mile (1.0 km) north along State
Road 173 from its intersection with State Road 622, 93 feet (28 m) east of the
NE corner of the house, 70 feet (21 m) SW of the SW corner of the Mills
Fisheries Company frame building, 67 feet (20 m) west of the shore end of a
wooden foot pier, and 1.5 feet (0.5 m) north of a witness sign.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 6
PUBLICATION DATE: 07/20/1990
Station ID: 8637686 SUPERCEDED DATE: 04/21/2003
Name: YORKTOWN, YORK RIVER
VIRGINIA
NOAA Chart: 12241 Latitude: 37° 13.4' N
USGS Quad: POQUOSON WEST Longitude: 76° 26.4' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: R 266 RESET 1956
MONUMENTATION: Survey Disk VM#: 3426
AGENCY: PID#: GV0384
SETTING CLASSIFICATION: Concrete Monument
The bench mark is 1.2 miles (1.9 km) SE along State Road 622 from the
intersection with State Road 173, 33 feet (10 m) south of the centerline of
State Road 622, 20 feet (6 m) west of a private road, and 2 feet (1 m) north of
a white wooden witness post.
BENCH MARK STAMPING: CHARLIE 1972
MONUMENTATION: Survey Disk VM#: 3427
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Porch
The bench mark is set flush in a concrete porch at the entrance to the
superintendents office of the Virginia State Highway Commission on State Road
622, and 0.1 mile (0.2 km) from its intersection with State Road 173.
BENCH MARK STAMPING: NO 2 1972
MONUMENTATION: Survey Disk VM#: 3429
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Retaining Wall
The bench mark is set flush in the concrete retaining wall at the inshore end of
the pier at the NE corner of Yorktown Amoco Refinery, and 10.0 feet (3.0 m) west
of the centerline of the pier.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 6
PUBLICATION DATE: 07/20/1990
Station ID: 8637686 SUPERCEDED DATE: 04/21/2003
Name: YORKTOWN, YORK RIVER
VIRGINIA
NOAA Chart: 12241 Latitude: 37° 13.4' N
USGS Quad: POQUOSON WEST Longitude: 76° 26.4' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 3 1972
MONUMENTATION: Survey Disk VM#: 3430
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Footing
The bench mark is set flush in the concrete footing of a steel tower supporting
a security light and camera, and 30.0 feet (9.1 m) east of the NE corner of the
security guard shack.
BENCH MARK STAMPING: TINKS 1972
MONUMENTATION: Survey Disk VM#: 3431
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Monument
The bench mark is set flush in a concrete monument on State Highway 622, 0.3
mile (0.5 km) west of the Zion United Methodist Church in front of Tinks garage
at VEPCO power pole #17, and 0.5 foot (0.2 m) above the ground.
BENCH MARK STAMPING: 7686 A 1982
MONUMENTATION: Survey Disk VM#: 3432
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Block
The bench mark is set flush in a 1.9 x 1.9 x 1-foot (0.6 x 0.6 x 0.3 m) concrete
block with a protruding 6-inch pipe, 150 feet (46 m) north of the north edge of
a canal, 100 feet (30 m) east of the centerline of Dock Road leading to the
Amoco pier, 9 feet (3 m) west of a large cylindrical tank, and just south of a
ladder.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 6
PUBLICATION DATE: 07/20/1990
Station ID: 8637686 SUPERCEDED DATE: 04/21/2003
Name: YORKTOWN, YORK RIVER
VIRGINIA
NOAA Chart: 12241 Latitude: 37° 13.4' N
USGS Quad: POQUOSON WEST Longitude: 76° 26.4' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 7686 B 1982
MONUMENTATION: Survey Disk VM#: 3433
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Column
The bench mark is set flush in the most northeasterly of six 2-foot (1 m)
diameter support columns for a van used as an electrical switching station, 91.0
feet (27.7 m) west of the centerline of Dock Road, 72.9 feet (22.2 m) NW of
power pole #76 SPSJ7 155 just north of the intersection of Dock Road and Avenue
A, and 65.1 feet (19.8 m) north of the north edge of the canal.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 6
PUBLICATION DATE: 07/20/1990
Station ID: 8637686 SUPERCEDED DATE: 04/21/2003
Name: YORKTOWN, YORK RIVER
VIRGINIA
NOAA Chart: 12241 Latitude: 37° 13.4' N
USGS Quad: POQUOSON WEST Longitude: 76° 26.4' W
T I D A L D A T U M S
Tidal datums at YORKTOWN, YORK RIVER based on:
LENGTH OF SERIES: 13 MONTHS
TIME PERIOD: JUNE 1972 - NOVEMBER 1973
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8637624 GLOUCESTER POINT
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (10/06/1972) = 5.18
MEAN HIGHER HIGH WATER (MHHW) = 2.56
MEAN HIGH WATER (MHW) = 2.43
MEAN TIDE LEVEL (MTL) = 1.30
MEAN LOW WATER (MLW) = 0.17
MEAN LOWER LOW WATER (MLLW) = 0.00
LOWEST OBSERVED WATER LEVEL (12/18/1972) = -2.13
National Geodetic Vertical Datum (NGVD 29)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
NO 1 1972 16.97 14.54
T 266 1942 3.88 1.45
R 266 RESET 1956 11.85 9.42
CHARLIE 1972 16.02 13.59
NO 2 1972 15.54 13.11
NO 3 1972 10.86 8.43
TINKS 1972 12.27 9.84
7686 A 1982 11.05 8.62
7686 B 1982 12.30 9.87
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 6
PUBLICATION DATE: 07/20/1990
Station ID: 8637686 SUPERCEDED DATE: 04/21/2003
Name: YORKTOWN, YORK RIVER
VIRGINIA
NOAA Chart: 12241 Latitude: 37° 13.4' N
USGS Quad: POQUOSON WEST Longitude: 76° 26.4' 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 (NAVD 88).
NGVD 29 is a fixed datum adopted as a national standard geodetic reference for
heights but is now considered superseded. NGVD 29 is sometimes referred to as
Sea Level Datum of 1929 or as Mean Sea Level on some early issues of Geological
Survey Topographic Quads. NGVD 29 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 NGVD 29 are available from the National
Geodetic Survey (NGS) data base via the World Wide Web at
National Geodetic Survey.
NAVD 88 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. NAVD 88 replaces NGVD 29 as the national
standard geodetic reference for heights. Bench mark elevations relative to
NAVD 88 are available from NGS through the World Wide Web at
National Geodetic Survey.
NGVD 29 and NAVD 88 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 NAVD 88 elevation is shown on the Elevations of Tidal Datums Table Referred
to MLLW only when two or more of the bench marks listed have NAVD 88 elevations.
The NAVD 88 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, NAVD 88 bench mark elevations computed indirectly from the tidal
datums elevation table may differ slightly from NAVD 88 elevations listed for
each bench mark in the NGS database.