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National Ocean Service
Datums Page Page 1 of 8
Station ID: 8458022 PUBLICATION DATE: 11/07/2016
Name: WEEKAPAUG POINT, BLOCK ISLAND SOUND
RI
NOAA Chart: 13215 Latitude: 41° 19.7' N ( 41.32830)
USGS Quad: WATCH HILL Longitude: 71° 45.7' W ( -71.76170)
To reach the tidal bench marks from the Post Office in Watch Hill, proceed 0.8
km (0.5 mi) NE on Westerly Road, then 3.1 km (1.9 mi) NE on Ocean View Highway,
then 6.6 km (4.1 mi) NE on Shore Road, then 1.1 km (0.7 mi) south on Weekapaug
Road to Weekapaug Inlet. The bench marks are located in the vicinity of the
inlet, Weekapaug Road, and Noyes Neck Road to the east. The tide gage was
located on the east shore of the inlet near the mouth.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: WKP 2 1997
DESIGNATION: 845 8022 WKP 2
MONUMENTATION: Tidal Station disk VM#: 13917
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 41° 19.7' N ( 41.32830) LONGITUDE: 71° 45.7' W ( -71.76170)
The bench mark is a disk set in a rock outcrop monument for the Weekapaug
Bicentennial Celebration on the east side of Weekapaug Breachway, 13 m (43 ft)
south of an asphalt drive leading to the memorial grounds, 12 m (38 ft) east of
the centerlline of Wawaloam Drive, 3.51 m (11.5 ft) west of a white flag pole,
and 1.68 m (5.5 ft) north of the south end of the rock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 8
Station ID: 8458022 PUBLICATION DATE: 11/07/2016
Name: WEEKAPAUG POINT, BLOCK ISLAND SOUND
RI
NOAA Chart: 13215 Latitude: 41° 19.7' N ( 41.32830)
USGS Quad: WATCH HILL Longitude: 71° 45.7' W ( -71.76170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: WKP 1 1997
DESIGNATION: 845 8022 WKP 1
MONUMENTATION: Tidal Station disk VM#: 13918
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete pad OPUS PID:
LATITUDE: 41° 19.7' N ( 41.32830) LONGITUDE: 71° 45.7' W ( -71.76170)
The bench mark is a disk set in the NE corner of a 1.98 m (6.5 ft) square
concrete foundation that supports the tide gage, on the east shore of Weekapaug
Breachway near the mouth, 16 m (52 ft) west of the centerline of a parking lot
for the Weekapaug Fire District private beach, and 4 m (13 ft) east of the
water's edge.
BENCH MARK STAMPING: WKP 3 1997
DESIGNATION: 845 8022 WKP 3
MONUMENTATION: Tidal Station disk VM#: 13919
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete pad OPUS PID:
LATITUDE: 41° 19.7' N ( 41.32830) LONGITUDE: 71° 45.7' W ( -71.76170)
The bench mark is a disk set in the SW corner of a 1 m x 2 m (3 ft x 6 ft)
concrete pad, 26 m (85 ft) south of the intersection of Wawaloam Drive and
Atlantic Avenue, 17 m (56 ft) north of the dirveway entrance to a fishing pier,
12 m (38 ft) west of the centerline of a parking lot for the Weekapaug Fishing
Area, and 9 m (28 ft) west of Wawaloam Drive.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 8
Station ID: 8458022 PUBLICATION DATE: 11/07/2016
Name: WEEKAPAUG POINT, BLOCK ISLAND SOUND
RI
NOAA Chart: 13215 Latitude: 41° 19.7' N ( 41.32830)
USGS Quad: WATCH HILL Longitude: 71° 45.7' W ( -71.76170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING:
DESIGNATION: 845 8022 NO STAMPING 1
MONUMENTATION: Chiseled Cross VM#: 13920
AGENCY: Unknown IDB PID#:
SETTING CLASSIFICATION: Concrete foot bridge OPUS PID:
LATITUDE: 41° 19.4' N ( 41.32330) LONGITUDE: 71° 45.2' W ( -71.75330)
The bench mark is a drill hole with cross cut located at the SE end of a
concrete foot bridge near the junction of Atlantic Avenue and Weekapaug
Breachway, 29.72 m (97.5 ft) north of the centerline of Atlantic Avenue, 20.97 m
(68.8 ft) NE of the SE corner of the two story concrete Seafood Haven, 8.93 m
(29.3 ft) south of the north end of the foot bridge, and 6.25 m (20.5 ft) east
of the SW corner fo the bridge.
BENCH MARK STAMPING: WKP 5 1997
DESIGNATION: 845 8022 WKP 5
MONUMENTATION: Tidal Station disk VM#: 13921
AGENCY: National Ocean Service (NOS) IDB PID#:
SETTING CLASSIFICATION: Concrete foundation OPUS PID#: BBDJ51
LATITUDE: 41° 19.7' N ( 41.32830) LONGITUDE: 71° 45.7' W ( -71.76170)
The bench mark is a disk set in the center of a 1.98 m (6.5 ft) square concrete
foundation with steps on the west side of Weekapaug Breachway, 76 m (250 ft)
south of the Atlantic Avenue bridge, 59 m (194 ft) east of the centerline of a
parking lot for the Dunes private beach, and 4 m (13 ft) west of the water's
edge.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 8
Station ID: 8458022 PUBLICATION DATE: 11/07/2016
Name: WEEKAPAUG POINT, BLOCK ISLAND SOUND
RI
NOAA Chart: 13215 Latitude: 41° 19.7' N ( 41.32830)
USGS Quad: WATCH HILL Longitude: 71° 45.7' W ( -71.76170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: CHAPMAN 1934
DESIGNATION: CHAPMAN
MONUMENTATION: Triangulation Station disk VM#: 13922
AGENCY: US Army Corps of Engineers (USE) IDB PID#: LW0822
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 41° 19.9' N ( 41.33170) LONGITUDE: 71° 45.4' W ( -71.75670)
The bench mark is a disk set in a 3 m x 5 m (9 ft x 18 ft) rock outcrop 152 m
(500 ft) south along Noyes Point Road from its intersection with Chapman Road,
66 m (217 ft) west of Noyes Point Road, 38 m (125 ft) NE of the NE corner of a
house, 9.40 m (30.8 ft) north of the centerline of the driveway, 7.89 m (25.9
ft) NW of power pole No. 4999, 1.31 m (4.3 ft) south of a 0.3 m (1 ft) diameter
cedar tree, and at ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 8
Station ID: 8458022 PUBLICATION DATE: 11/07/2016
Name: WEEKAPAUG POINT, BLOCK ISLAND SOUND
RI
NOAA Chart: 13215 Latitude: 41° 19.7' N ( 41.32830)
USGS Quad: WATCH HILL Longitude: 71° 45.7' W ( -71.76170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: CHAPMAN 1 1934
DESIGNATION: CHAPMAN RM 1 USE
MONUMENTATION: Reference Mark disk VM#: 13923
AGENCY: US Army Corps of Engineers (USE) IDB PID#: LW0823
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 41° 19.9' N ( 41.33170) LONGITUDE: 71° 45.4' W ( -71.75670)
The bench mark is a disk set in the top of a 1 m x 2 m (3 ft x 7 ft) rock
outcrop 68 m (223 ft) west of Noyes Point Road, 40 m (131 ft) NE of the NE
corner of a house, 15 M (49 FT) NW of power pole No. 4999, 12.31 m (40.4 ft) NNW
of the centerline of the driveway, 8.38 m (27.5 ft) NW of bench mark CHAPMAN
1934, and 0.15 m (0.5 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 6 of 8
Station ID: 8458022 PUBLICATION DATE: 11/07/2016
Name: WEEKAPAUG POINT, BLOCK ISLAND SOUND
RI
NOAA Chart: 13215 Latitude: 41° 19.7' N ( 41.32830)
USGS Quad: WATCH HILL Longitude: 71° 45.7' W ( -71.76170)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: NOYES POINT OP 1 1940
DESIGNATION: NOYES POINT OP 1
MONUMENTATION: Reference Mark disk VM#: 13924
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: LW0821
SETTING CLASSIFICATION: Rock outcrop OPUS PID:
LATITUDE: 41° 19.9' N ( 41.33170) LONGITUDE: 71° 45.4' W ( -71.75670)
The bench mark is set in a 1 m (2 ft) square rock outcrop in the vicinity of
bench mark CHAPMAN 1934, 60 m (197 ft) west of Noyes Point Road, 58 m (190 ft)
NE of the NE corner of a house, 21.79 m (71.5 ft) NE of power pole No. 4999,
21.21 m (69.6 ft) north of the centerline of the driveway, 3.51 m (11.5 ft) east
of a 0.3 m (1 ft) diameter cedar tree, and at ground level.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 8
Station ID: 8458022 PUBLICATION DATE: 11/07/2016
Name: WEEKAPAUG POINT, BLOCK ISLAND SOUND
RI
NOAA Chart: 13215 Latitude: 41° 19.7' N ( 41.32830)
USGS Quad: WATCH HILL Longitude: 71° 45.7' W ( -71.76170)
T I D A L D A T U M S
Tidal datums at WEEKAPAUG POINT, BLOCK ISLAND SOUND based on:
LENGTH OF SERIES: 1 MONTH
TIME PERIOD: October 1997 - October 1997
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8452660 NEWPORT, NARRAGANSETT BAY
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 0.876
MEAN HIGH WATER MHW = 0.810
MEAN TIDE LEVEL MTL = 0.425
MEAN SEA LEVEL MSL = 0.418
MEAN LOW WATER MLW = 0.040
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
WKP 2 1997 3.491 2.681
WKP 1 1997 3.180 2.370
WKP 3 1997 2.519 1.709
845 8022 NO STAMPING 1 3.586 2.776
WKP 5 1997 2.893 2.083
CHAPMAN 1934 19.987 19.177
CHAPMAN 1 1934 20.237 19.427
NOYES POINT OP 1 1940 19.961 19.151
Foot Notes:
Bench marks CHAPMAN 1934, CHAPMAN 1 1934, and NOYES POINT OP 1 1940 are based on
one differential leveling connection and do not meet the quality control
standards of the NOS. Therefore, caution should be used when deriving elevations
for these marks.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 8 of 8
Station ID: 8458022 PUBLICATION DATE: 11/07/2016
Name: WEEKAPAUG POINT, BLOCK ISLAND SOUND
RI
NOAA Chart: 13215 Latitude: 41° 19.7' N ( 41.32830)
USGS Quad: WATCH HILL Longitude: 71° 45.7' W ( -71.76170)
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.