U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 9751774 PUBLICATION DATE: 11/03/2011
Name: BOTANY BAY, ST THOMAS
VI
NOAA Chart: 25641 Latitude: 18° 21.8' N ( 18.36330)
USGS Quad: WESTERN ST. THOMAS Longitude: 65° 2.1' W ( -65.03500)
To reach the bench marks by car from the Cyril E. King Airport on St Thomas,
proceed 1.4 km (0.9 mi) east on Airport Road, then turn left and proceed west on
a winding Route 30 for 11.3 km (7.0 mi) to the gated entrance to Botany Bay
Preserve development on the right, proceed through the gates and turn left and
follow the winding concrete road 1.7 km (1.0 mi) west which turns into two
strips of concrete and finally a gravel drive near the Botany Bay beach house.
The bench marks are in the vicinity of the beach house and the rock point to the
south between Botany Bay and Sandy Bay. The tide gauge orifices are on the
north side of the rock point and the tide gauge enclosure is on the south side
of the rock point.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 1 1975
DESIGNATION: 975 1774 TIDAL 1
MONUMENTATION: Bench Mark disk VM#: 20024
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete patio OPUS PID:
LATITUDE: 18° 21.4' N ( 18.35603) LONGITUDE: 65° 2.0' W ( -65.03264)
The primary bench mark is a disk set in the west edge of the beach house pool
concrete patio, 24.33 m (79.8 ft) NNE from the center of the kitchen doorway
inside the beach house, 16.07 m (52.7 ft) SW from the NW corner of the pool
patio, 3.82 m (12.5 ft) NW from the seaward side of the pool, and 1.76 m (5.8
ft) NNE from a coral and stone bench facing the pool.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 9751774 PUBLICATION DATE: 11/03/2011
Name: BOTANY BAY, ST THOMAS
VI
NOAA Chart: 25641 Latitude: 18° 21.8' N ( 18.36330)
USGS Quad: WESTERN ST. THOMAS Longitude: 65° 2.1' W ( -65.03500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: USCGS
DESIGNATION: 975 1774 USCGS
MONUMENTATION: Bench Mark disk VM#: 20025
AGENCY: NGS or CGS (USC&GS) IDB PID#:
SETTING CLASSIFICATION: Bedrock OPUS PID#: BBCK23
LATITUDE: 18° 21.3' N ( 18.35506) LONGITUDE: 65° 2.1' W ( -65.03461)
The bench mark is a disk set flush in the bedrock point between Sandy Bay and
Botany Bay, 13.90 m (42.6 ft) east from the seaward end of the rock point, 5.92m
(19.4 ft) WNW from a 5.00 m (16.4 ft) high rock cliff at the base of the point,
1.13 m (3.7 ft) east from the west edge of the rock which is 1.00 m (3.3 ft)
above the rock below, and 0.85 m (2.8 ft) north of the south edge of the rock
which is 1.00 m (3.3 ft) above the rock below.
BENCH MARK STAMPING: NO 4 1975
DESIGNATION: 975 1774 TIDAL 4
MONUMENTATION: Bench Mark disk VM#: 20029
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete on top of culvert OPUS PID:
LATITUDE: 18° 21.4' N ( 18.35589) LONGITUDE: 65° 1.9' W ( -65.03175)
The bench mark is a disk set flush in concrete on top of a culvert on the west
side of the main road which is 2 parallel strips of concrete, 34.38 m (112.8 ft)
NE from the center of the door on a wooden garden shed, 21.02 m (69.0 ft) SW
from the far north end of a 3.00 m (9.8 ft) tall stone retaining wall in front
of a house, and 1.35 m (4.4 ft) west from the western edge of the road.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 9751774 PUBLICATION DATE: 11/03/2011
Name: BOTANY BAY, ST THOMAS
VI
NOAA Chart: 25641 Latitude: 18° 21.8' N ( 18.36330)
USGS Quad: WESTERN ST. THOMAS Longitude: 65° 2.1' W ( -65.03500)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NO 5 1975
DESIGNATION: 975 1774 TIDAL 5
MONUMENTATION: Bench Mark disk VM#: 20030
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Stone and concrete step OPUS PID:
LATITUDE: 18° 21.4' N ( 18.35631) LONGITUDE: 65° 1.9' W ( -65.03169)
The bench mark is a disk set flush in the bottom stone and concrete step of the
ruins of the sugar mill building, 15.95 m (52.3 ft) NE from the center of the
step on the east side of a 5.00 m (16.4 ft) diameter circular concrete well,
11.64 m (38.2 ft) north from the SW corner of the building, 4.29 m (14.1 ft)
west from a stone doorway facing NW, and 3.82 m (12.5 ft) ESE from the west
corner of the building.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 9751774 PUBLICATION DATE: 11/03/2011
Name: BOTANY BAY, ST THOMAS
VI
NOAA Chart: 25641 Latitude: 18° 21.8' N ( 18.36330)
USGS Quad: WESTERN ST. THOMAS Longitude: 65° 2.1' W ( -65.03500)
T I D A L D A T U M S
Tidal datums at BOTANY BAY, ST THOMAS based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: May 2011 - July 2011
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 9755371 SAN JUAN, LA PUNTILLA, SAN JUAN BAY
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 0.391
MEAN HIGH WATER MHW = 0.313
MEAN SEA LEVEL MSL = 0.179
MEAN TIDE LEVEL MTL = 0.176
MEAN LOW WATER MLW = 0.039
MEAN LOWER LOW WATER MLLW = 0.000
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
NO 1 1975 2.859 2.546
USCGS 2.309 1.996
NO 4 1975 3.683 3.370
NO 5 1975 2.465 2.152
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 9751774 PUBLICATION DATE: 11/03/2011
Name: BOTANY BAY, ST THOMAS
VI
NOAA Chart: 25641 Latitude: 18° 21.8' N ( 18.36330)
USGS Quad: WESTERN ST. THOMAS Longitude: 65° 2.1' W ( -65.03500)
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 any other fixed island datum.
This tide station location has a defined island datum (VIVD09). Island datums
are specific fixed geodetic datums whose elevation relationship to local MSL
and other tidal datums may not be consistent from one location to another.
Virgin Islands Vertical Datum of 2009 (VIVD09) is a fixed datum derived from
a simultaneous, least squares, minimum constraint adjustment of leveling
observations. Local mean sea level relative to the 1983-2001 National Tidal
Datum Epoch observed at tide stations 9751401 located at Lime Tree Bay,
St. Croix, 9751381 located at Lameshur Bay, St. John, and 9751639 located at
Charlotte Amalie, St Thomas was held fixed as the single initial constraint.
VIVD09 replaces all previous height system as the national standard geodetic
reference for heights in the Virgin Islands. Bench mark elevations relative
to VIVD09 are available from NGS through the World Wide Web at
National Geodetic Survey.
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 VIVD09 elevation is shown on the Elevations of Tidal Datums Table Referred
to MLLW only when two or more of the bench marks listed have VIVD09 elevations.
The VIVD09 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, VIVD09 bench mark elevations computed indirectly from the tidal
datums elevation table may differ slightly from VIVD09 elevations listed for
each bench mark in the NGS database.