U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8638339 PUBLICATION DATE: 03/27/2012
Name: WESTERN BRANCH
VA
NOAA Chart: 12253 Latitude: 36° 49.4' N ( 36.82322)
USGS Quad: Bowers Hill Longitude: 76° 23.9' W ( -76.39911)
TO REACH THE TIDAL STATION DISKS FROM THE INTERSECTION OF PORTSMOUTH BOULEVARD
AND THE ELIZABETH RIVER AT THE HODGES FERRY BRIDGE, PROCEED WEST FOR 322.9 M
(1059.4 FT) ON PORTSMOUTH BOULEVARD TO THE INTERSECTION OF LAKEWOOD LANE AND
PORTSMOUTH BOULEVARD, THEN TURN LEFT ONTO LAKEWOOD LANE AND PROCEED TO THE
ADDRESS 3809 PORTSMOUTH BOULEVARD. THE BENCH MARKS ARE LOCATED IN THE VICINITY
ALONG PORTSMOUTH BOULEVARD AND IN THE BACKYARD OF 3809 PORTSMOUTH BOULEVARD. THE
TIDE GAUGE IS LOCATED AT THE END OF THE PIER LOCATED IN THE BACKYARD OF 3809
PORTSMOUTH BOULEVARD. 3809 Portsmouth Blvd Chesapeake VA
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 8339 A 2011
DESIGNATION: 863 8339 A
MONUMENTATION: Flange-encased Rod VM#: 19903
AGENCY: CO-OPS IDB PID#:
SETTING CLASSIFICATION: Sainless steel rod OPUS PID#: BBCG95
LATITUDE: 36° 49.4' N ( 36.82322) LONGITUDE: 76° 24.0' W ( -76.39986)
The primary bench mark is 23.71 m (77.8 ft) north of rip rap running east/west,
21.50 m (70.5 ft) east of rip rap running north/south, 19.0 m (62.3 ft)
southeast of the southeast corner of guest house, and 0.07 m (0.2 ft) below
grade. The bench mark is a flange encased rod with concrete kick block at the
east end of 3809 Portsmouth Boulevard between the east end of the guest house
and the edge of the water.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8638339 PUBLICATION DATE: 03/27/2012
Name: WESTERN BRANCH
VA
NOAA Chart: 12253 Latitude: 36° 49.4' N ( 36.82322)
USGS Quad: Bowers Hill Longitude: 76° 23.9' W ( -76.39911)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 8339 B 2011
DESIGNATION: 863 8339 B
MONUMENTATION: Tidal Station disk VM#: 19904
AGENCY: CO-OPS IDB PID#:
SETTING CLASSIFICATION: Sidewalk OPUS PID:
LATITUDE: 36° 49.5' N ( 36.82417) LONGITUDE: 76° 24.0' W ( -76.39942)
The mark is a tidal station disk set in concrete on the Hodges Ferry Bridge, at
the west end of the bridge located on the sidewalk, 7.98 m (26.2 ft) southeast
of reduced speed ahead sign, 1.39 m (4.6 ft) west of light pole number 0215
5173, and 1.34 m (4.4 ft) southwest of southwest curb of Portsmouth Boulevard.
Note - the bench mark does not meet the specifications of a class 'A' rod mark.
BENCH MARK STAMPING: 8339 C 2011
DESIGNATION: 863 8339 C
MONUMENTATION: Tidal Station disk VM#: 19905
AGENCY: CO-OPS IDB PID#:
SETTING CLASSIFICATION: Sidewalk OPUS PID:
LATITUDE: 36° 49.5' N ( 36.82417) LONGITUDE: 76° 24.1' W ( -76.40113)
The bench mark is a tidal station disk set in concrete east of the intersection
of Lakewood Lane and Portsmouth Boulevard, located adjacent to a man hole cover,
13.65 m (44.8 ft) northeast of light pole number N0215 I18, .90 m (3.0 ft) east
of man hole cover, .71 m (2.3 ft) south of south curb of Portsmouth Boulevard.
Note - the bench mark does not meet the specifications of a class 'A' rod mark.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8638339 PUBLICATION DATE: 03/27/2012
Name: WESTERN BRANCH
VA
NOAA Chart: 12253 Latitude: 36° 49.4' N ( 36.82322)
USGS Quad: Bowers Hill Longitude: 76° 23.9' W ( -76.39911)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 8339 D 2011
DESIGNATION: 863 8339 D
MONUMENTATION: Tidal Station disk VM#: 19906
AGENCY: CO-OPS IDB PID#:
SETTING CLASSIFICATION: Sidewalk OPUS PID:
LATITUDE: 36° 49.5' N ( 36.82417) LONGITUDE: 76° 24.1' W ( -76.40113)
The bench mark is a tidal station disk set in concrete west of the intersection
of Lakewood Lane and Portsmouth Boulevard, located adjacent to a man hole cover,
19.12 m (62.7 ft) east of power pole 1167, 14.56 m (47.8 ft) east of fire
hydrant southeast of reduced speed ahead sign, 2.12 m (7.0 ft) northwest of
northwest corner of drain. Note - the bench mark does not meet the
specifications of a class 'A' rod mark.
BENCH MARK STAMPING: 8339 E 2011
DESIGNATION: 863 8339 E
MONUMENTATION: Tidal Station disk VM#: 19907
AGENCY: CO-OPS IDB PID#:
SETTING CLASSIFICATION: Sidewalk OPUS PID:
LATITUDE: 36° 49.5' N ( 36.82466) LONGITUDE: 76° 24.2' W ( -76.40339)
The bench mark is a tidal station disk set in concrete on the sidewalk adjacent
to Portsmouth Boulevard located near a gardening center, 17.10 m (56.0 ft) east
of power pole number HI38, 17.06 m (56.0 ft) northeast of light pole, .74 m (2.4
ft) south of south curb of Portsmouth Boulevard. Note - the bench mark does
not meet the specifications of a class 'A' rod mark.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8638339 PUBLICATION DATE: 03/27/2012
Name: WESTERN BRANCH
VA
NOAA Chart: 12253 Latitude: 36° 49.4' N ( 36.82322)
USGS Quad: Bowers Hill Longitude: 76° 23.9' W ( -76.39911)
T I D A L D A T U M S
Tidal datums at WESTERN BRANCH based on:
LENGTH OF SERIES: 6 MONTHS
TIME PERIOD: April 2011 - September 2011
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:
MEAN HIGHER HIGH WATER MHHW = 0.951
MEAN HIGH WATER MHW = 0.887
MEAN SEA LEVEL MSL = 0.470
MEAN TIDE LEVEL MTL = 0.466
MEAN LOW WATER MLW = 0.044
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
8339 A 2011 1.697 0.810
8339 B 2011 7.667 6.780
8339 C 2011 4.793 3.906
8339 D 2011 4.949 4.062
8339 E 2011 4.547 3.661
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8638339 PUBLICATION DATE: 03/27/2012
Name: WESTERN BRANCH
VA
NOAA Chart: 12253 Latitude: 36° 49.4' N ( 36.82322)
USGS Quad: Bowers Hill Longitude: 76° 23.9' W ( -76.39911)
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.