U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8638449 PUBLICATION DATE: 04/29/2003
Name: CLAREMONT, JAMES RIVER
VIRGINIA
NOAA Chart: 12251 Latitude: 37° 13.9' N
USGS Quad: CLAREMONT Longitude: 76° 56.9' W
To reach the tidal bench marks from the Claremont Post Office, proceed east on
County Road T 613 for 1.1 km (0.7 mi) and then SE on County Road T 1202 for 0.3
km (0.2 mi) to the circle at the end of the road. The bench marks are near the
center of the circle at the end of the road, and along the south bank of James
River. The tide gage and staff were at the NE end of an abandoned Navy pier.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: BM 6 1951
DESIGNATION: 863 8449 BM 6
MONUMENTATION: Tidal Station disk VM#: 3456
AGENCY: US Coast and Geodetic Survey (USC&GS) PID:
SETTING CLASSIFICATION: Water tower foundation
The primary bench mark is a disk set in the SW corner of the westernmost of the
two northern concrete foundations of the legs of the water tower located about
midway between the abandoned Navy pier and the Claremont-Sandy Point ferry slip,
6.1 m (20 ft) east of the property line fence at the gate, and 0.3 m (1 ft)
above ground level.
BENCH MARK STAMPING: NO 7 1970
DESIGNATION: TIDAL 7 STA 81
MONUMENTATION: Tidal Station disk VM#: 3457
AGENCY: National Ocean Survey (NOS) PID#: GV0448
SETTING CLASSIFICATION: Boat ramp
The bench mark is a disk set in the top of the west corner of a boat ramp
leading to the James River from the garage of a concrete block house along
County Road T 1202, 30.94 m (101.5 ft) NW of Bench Mark A 453, 19.5 m (64 ft) NW
of the centerline of the road along the NW side of the circle at the end of the
road, 9.1 m (30 ft) SW of the approximate shoreline, and 0.67 m (2.2 ft) east of
the north corner of the house.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8638449 PUBLICATION DATE: 04/29/2003
Name: CLAREMONT, JAMES RIVER
VIRGINIA
NOAA Chart: 12251 Latitude: 37° 13.9' N
USGS Quad: CLAREMONT Longitude: 76° 56.9' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 8 1970
DESIGNATION: 863 8449 TIDAL 8
MONUMENTATION: Tidal Station disk VM#: 3458
AGENCY: National Ocean Survey (NOS) PID:
SETTING CLASSIFICATION: Driveway
The bench mark is a disk set in the driveway of the seventh house east of Bench
Mark BM 6 1951, 0.18 m (0.6 ft) from the garage door.
BENCH MARK STAMPING: A 453 1971
DESIGNATION: A 453
MONUMENTATION: Bench Mark disk VM#: 3459
AGENCY: National Geodetic Survey (NGS) PID#: GV0447
SETTING CLASSIFICATION: Copper-clad steel rod
The bench mark is a disk located near the center of a circle at the end of
County Road T 1202, 20.4 m (67 ft) SE of the east corner of a concrete block
house, 14.3 m (47 ft) NW of the centerline of the road along the SE side of the
circle, 11.3 m (37 ft) SE of the centerline of the road along the NW side of the
circle, 10.7 m (35 ft) north of a 0.6 m (2 ft) diameter oak tree, and 0.46 m
(1.5 ft) NW of a metal witness post. The bench mark is crimped to a copper-clad
steel rod driven 21.9 m (72 ft) to refusal, and encased in a 4-inch metal pipe.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8638449 PUBLICATION DATE: 04/29/2003
Name: CLAREMONT, JAMES RIVER
VIRGINIA
NOAA Chart: 12251 Latitude: 37° 13.9' N
USGS Quad: CLAREMONT Longitude: 76° 56.9' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: B 453 1971
DESIGNATION: B 453
MONUMENTATION: Bench Mark disk VM#: 3460
AGENCY: National Geodetic Survey (NGS) PID#: GV0449
SETTING CLASSIFICATION: Copper-clad steel rod
The bench mark is a disk located in the vicinity of the abandoned Navy pier,
118.9 m (390 ft) NE of the centerline of County Road T 1202, 80.5 m (264 ft) SE
of the center of the circle at the end of the road, 26.8 m (88 ft) north of the
north porch corner for a one story residence, 21.0 m (69 ft) SW of the SW end of
the abandoned Navy pier, 15.5 m (51 ft) SW of the approximate shoreline, and
0.46 m (1.5 ft) SW of a metal witness post. The bench mark is crimped to a
copper-clad steel rod driven 21.6 m (71 ft) to refusal and encased in a 4-inch
steel pipe.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8638449 PUBLICATION DATE: 04/29/2003
Name: CLAREMONT, JAMES RIVER
VIRGINIA
NOAA Chart: 12251 Latitude: 37° 13.9' N
USGS Quad: CLAREMONT Longitude: 76° 56.9' W
T I D A L D A T U M S
Tidal datums at CLAREMONT, JAMES RIVER based on:
LENGTH OF SERIES: 36 MONTHS
TIME PERIOD: February 1971 - January 1974
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8638610 SEWELLS POINT, HAMPTON ROADS
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (10/06/1972) = 1.391
MEAN HIGHER HIGH WATER (MHHW) = 0.647
MEAN HIGH WATER (MHW) = 0.589
MEAN SEA LEVEL (MSL) = 0.334
MEAN TIDE LEVEL (MTL) = 0.317
MEAN LOW WATER (MLW) = 0.045
MEAN LOWER LOW WATER (MLLW) = 0.000
LOWEST OBSERVED WATER LEVEL (01/27/1971) = -0.841
National Geodetic Vertical Datum (NGVD 29)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
BM 6 1951 1.555 0.966
NO 7 1970 1.496 0.907
NO 8 1970 1.694 1.105
A 453 1971 1.305 0.716
B 453 1971 1.094 0.505
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8638449 PUBLICATION DATE: 04/29/2003
Name: CLAREMONT, JAMES RIVER
VIRGINIA
NOAA Chart: 12251 Latitude: 37° 13.9' N
USGS Quad: CLAREMONT Longitude: 76° 56.9' 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.