U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 7
Station ID: 8638445 PUBLICATION DATE: 05/12/2015
Name: LANEXA, CHICKAHOMINY RIVER
VA
NOAA Chart: 12251 Latitude: 37° 24.2' N ( 37.40330)
USGS Quad: WALKERS Longitude: 76° 54.7' W ( -76.91170)
To reach the bench marks by car from the junction of State Route 60 (Pocahontas
Hwy) and County Road 627 (Waterside Drive, a cross road), go southerly on
Waterside Drive 2.4 km (1.5 mi) to a red frame building on the right (and tidal
bench mark 863 8445 Tidal 1), continue westerly and down the hill for 1.0 km
(0.62 mi) to a sharp left and the CSX railroad crossing, continue south and
immediately after crossing the railroad tracks turn left onto Marina Road and go
east for 0.6 km (0.4 mi) to bench mark 863 8445 D on the left in triangular
median, bear right and go 0.3 km (0.2 mi) to Colonial Harbor Marina at 14910
Marina Road, Lanexa, Va 23089. The tide gauges were located in the NE corner of
the marina building, the sensors were located at the east end of the dock on the
south side of the marine railway. The staff was located at the east end of a
short dock on the north side of the marine railway.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 1 1947
DESIGNATION: 863 8445 TIDAL 1
MONUMENTATION: Bench Mark disk VM#: 18541
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Concrete pad OPUS PID:
LATITUDE: 37° 24.3' N ( 37.40500) LONGITUDE: 76° 54.7' W ( -76.91170)
The primary bench mark is a disk set flush in the SW corner of a 1.50 m x 5.50 m
(4.9 ft x 18.0 ft) concrete pad in front of a red frame building (old store) on
the north side of Waterside Drive, 0.97 km (0.60 mi) east of the CSX RR
crossing, 52.25m (171.4 ft) NNW of the centerline of the railroad tracks, 22.32
m (73.2 ft) NNW of the centerline of Waterside Drive, 9.03 m (29.6 ft) ESE of
the SW corner of the red frame building, 5.41m (17.7 ft) WSW of the SE corner of
the building, 3.48 m (11.4 ft) ESE of the SW corner of the bottom step, 1.32 m
(4.3 ft) south of the face of the building, 0.32 m (1.0 ft) ESE of west edge of
concrete pad, and 0.20m (0.7 ft) north of the south edge of the concrete pad.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 7
Station ID: 8638445 PUBLICATION DATE: 05/12/2015
Name: LANEXA, CHICKAHOMINY RIVER
VA
NOAA Chart: 12251 Latitude: 37° 24.2' N ( 37.40330)
USGS Quad: WALKERS Longitude: 76° 54.7' W ( -76.91170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 8445 A 2007
DESIGNATION: 863 8445 A
MONUMENTATION: Flange-encased Rod VM#: 18542
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID#: BBBG44
LATITUDE: 37° 24.1' N ( 37.40170) LONGITUDE: 76° 54.8' W ( -76.91330)
The bench mark is set in the grassy lawn SE of the Colonial Harbor Marina
building, 83.99 m (275.6 ft) ENE of bench mark 863 8445 B, 10.86 m (35.6 ft) SE
of the SE corner of the marina building, 10.49 m (34.4 ft) NE of a gas pump,
9.46 m (31.0 ft) north of the south edge of a east-west wooden walkway along the
water's edge, 8.78 m (28.8 ft) west of the wooden bulkhead, and 4.68 m (15.4 ft)
west of the white flagpole in the lawn. The bench mark is set 0.06 m (0.2 ft)
below the grade of the mowed lawn, being the top of a stainless steel rod driven
6.09 m (20.0 ft) to refusal, and encased in a 0.18 m (0.6 ft) diameter NOS logo
cover with a subsurface concrete kick block.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 7
Station ID: 8638445 PUBLICATION DATE: 05/12/2015
Name: LANEXA, CHICKAHOMINY RIVER
VA
NOAA Chart: 12251 Latitude: 37° 24.2' N ( 37.40330)
USGS Quad: WALKERS Longitude: 76° 54.7' W ( -76.91170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 8445 B 2007
DESIGNATION: 863 8445 B
MONUMENTATION: Bench Mark disk VM#: 18543
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete boat ramp OPUS PID#: BBDL40
LATITUDE: 37° 24.1' N ( 37.40170) LONGITUDE: 76° 54.9' W ( -76.91500)
The bench mark is a disk set flush in the top of the SW corner of the concrete
boat ramp next to the westerly most 8 inch diameter wood piling on the south
side of the concrete ramp at the Colonial Harbor Marina , 83.99 m (275.6 ft) WSW
of bench mark 863 8445 A, 77.10 m (253.0 ft) east of bench mark 863 8445 C,
52.32m (171.7 ft) east of the NE corner of the 25.0 m x 10.5 m (82.0 ft x 34.4
ft) metal shop building which is open on the west side, 6.21m (20.4 ft) south of
the NW corner of the concrete boat ramp, 6.12m (20.1 ft) west of the NE corner
of the plastic sheet pile on the south side of the boat ramp, and 0.15m (0.5 ft)
east of the west edge of the concrete boat ramp.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 7
Station ID: 8638445 PUBLICATION DATE: 05/12/2015
Name: LANEXA, CHICKAHOMINY RIVER
VA
NOAA Chart: 12251 Latitude: 37° 24.2' N ( 37.40330)
USGS Quad: WALKERS Longitude: 76° 54.7' W ( -76.91170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 8445 C 2007
DESIGNATION: 863 8445 C
MONUMENTATION: Bench Mark disk VM#: 18544
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete pier post OPUS PID:
LATITUDE: 37° 24.1' N ( 37.40170) LONGITUDE: 76° 54.9' W ( -76.91500)
The bench mark is a disk set flush in the top of the Northwesternly most
concrete pier post for the foundation of a 25.0 m x 10.5m (82.0 ft x 34.4 ft)
metal shop building which is open on the east side at the Colonial Harbor
Marina, 77.10 m (253.0 ft) west of bench mark 863 8445 B, 24.78 m (81.3 ft) west
of the NE corner of the building, 10.53 m (34.5 ft) north of the SW corner of
the building, 9.21 m (30.2 ft) ESE of a 0.35 m (1.1 ft) diameter pine tree on
the south side of the gravel access road, 9.05 m (29.7 ft) south of the
centerline of the gravel access road, 0.22 m (0.7 ft) east of the NW corner of
the building, 0.10 m (0.3 ft) north of the steel siding, and 0.06 m (0.2 ft)
above the ground.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 7
Station ID: 8638445 PUBLICATION DATE: 05/12/2015
Name: LANEXA, CHICKAHOMINY RIVER
VA
NOAA Chart: 12251 Latitude: 37° 24.2' N ( 37.40330)
USGS Quad: WALKERS Longitude: 76° 54.7' W ( -76.91170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 8445 D 2007
DESIGNATION: 863 8445 D
MONUMENTATION: Bench Mark disk VM#: 18545
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete post OPUS PID:
LATITUDE: 37° 24.3' N ( 37.40500) LONGITUDE: 76° 54.7' W ( -76.91170)
The bench mark is disk set flush in the top of a 1.38 m (4.5 ft) tall, 0.22m
(0.7 ft) diameter concrete post with imbedded rebar which is flush with the
ground in the southerly part of a triangle formed by the intersection of the
gravel access road to the Colonial Harbor Marina and a driveway leading easterly
to private residences, approximately 240 m (787 ft) northerly along the access
road from bench mark 863 8445 C, 46.83m (153.6 ft) east of the NE corner post of
a fenced field, 32.69 m (107.3 ft) south of centerline of the CSX railroad
tracks, 7.61m (25.0 ft) south of an east-west driveway, 7.53 m (24.7 ft) NE of
the centerline of the gravel access road to the marina, and 3.74 m (12.3 ft) SE
of the center of a decorative wooden lighthouse near the center of the triangle
made by the access road and driveway.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 7
Station ID: 8638445 PUBLICATION DATE: 05/12/2015
Name: LANEXA, CHICKAHOMINY RIVER
VA
NOAA Chart: 12251 Latitude: 37° 24.2' N ( 37.40330)
USGS Quad: WALKERS Longitude: 76° 54.7' W ( -76.91170)
T I D A L D A T U M S
Tidal datums at LANEXA, CHICKAHOMINY RIVER based on:
LENGTH OF SERIES: 1 YEAR
TIME PERIOD: July 2008 - June 2009
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 (09/26/2008) = 1.756
MEAN HIGHER HIGH WATER MHHW = 0.868
MEAN HIGH WATER MHW = 0.818
MEAN SEA LEVEL MSL = 0.451
MEAN TIDE LEVEL MTL = 0.428
MEAN LOW WATER MLW = 0.039
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (01/01/2009) = -0.528
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
NO 1 1947 7.670 6.852
8445 A 2007 1.060 0.242
8445 B 2007 1.099 0.281
8445 C 2007 1.912 1.094
8445 D 2007 3.712 2.894
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 7
Station ID: 8638445 PUBLICATION DATE: 05/12/2015
Name: LANEXA, CHICKAHOMINY RIVER
VA
NOAA Chart: 12251 Latitude: 37° 24.2' N ( 37.40330)
USGS Quad: WALKERS Longitude: 76° 54.7' W ( -76.91170)
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 NGS's Integrated Data Base (IDB PID)
provides geodetic datum based on traditionally leveled and bluebooked ties to
the National Spatial Reference System(NSRS) https://www.ngs.noaa.gov/datasheets/.
The NGS Online Positioning User Service (OPUS PID) provides geodetic datum based
on GPS position & tie it to the NSRS https://www.ngs.noaa.gov/OPUS/.
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.