U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8534836 PUBLICATION DATE: 05/12/2004
Name: LONGPORT, RISELY CHANNEL
NJ
NOAA Chart: 12316 Latitude: 39° 18.5' N ( 39.30830)
USGS Quad: OCEAN CITY Longitude: 74° 32.0' W ( -74.53330)
To reach the tidal bench marks from Longport, proceed to the intersection of
Atlantic Avenue and South 17th Avenue. The bench marks are located along
Atlantic and Beach Avenues and the tide gage and staff were located on a
platform attached to a privately owned pier in the channel.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: NO 9 1962
DESIGNATION: 853 4836 TIDAL 9
MONUMENTATION: Tidal Station disk VM#: 2735
AGENCY: US Coast & Geodetic Survey
(USC&GS) IDB PID#:
SETTING CLASSIFICATION: Concrete curb OPUS PID:
LATITUDE: 39° 18.5' N ( 39.30830) LONGITUDE: 74° 32.0' W ( -74.53330)
The bench mark is a disk set in concrete curb at the NW corner of Atlantic and
16th Avenues, 6.25 m (20.5 ft) from the NW corner of Ocean Bay Motel, and 0.6 m
(2 ft) from a fire hydrant.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8534836 PUBLICATION DATE: 05/12/2004
Name: LONGPORT, RISELY CHANNEL
NJ
NOAA Chart: 12316 Latitude: 39° 18.5' N ( 39.30830)
USGS Quad: OCEAN CITY Longitude: 74° 32.0' W ( -74.53330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4836 E 1977
DESIGNATION: 853 4836 E 1977
MONUMENTATION: See descriptive text VM#: 2736
AGENCY: IDB PID#: JU4236
SETTING CLASSIFICATION: OPUS PID:
LATITUDE: ' °deg (0) LONGITUDE: ' °deg (0)
The bench mark is a disk crimped to a galvanized steel rod, located 32.46 m
(106.5 ft) SE of the easternmost end of a wood bulkhead on the west side of
Atlantic Avenue, 31.15 m (102.2 ft) NE of the SW tip of the concrete curb tip of
the traffic island, 18.47 m (60.6 ft) NW of wood utility pole #6936 and 1.65 m
(5.4 ft) SW of the NE side of the triangle. The bench mark is 0.06 m (0.2 ft)
below ground level, crimped to a galvanized steel rod driven 9 m (31 ft) to
refusal, and encased in PVC pipe and concrete kickblock.
BENCH MARK STAMPING: 4836 F 1977
DESIGNATION: 853 4836 F TIDAL
MONUMENTATION: Tidal Station disk VM#: 2737
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Galvanized steel rod OPUS PID:
LATITUDE: 39° 18.5' N ( 39.30830) LONGITUDE: 74° 32.0' W ( -74.53330)
The bench mark is a disk located 18.59 m (61.0 ft) east of the south corner of
the house at 1509 Beach Avenue, 11.73 m (38.5 ft) SW of the centerline of 16th
Street, 6.52 m (21.4 ft) south of the outside corner of the concrete wall
alongside Beach Avenue, 5.49 m (18.0 ft) south of wood utility pole #A16674, and
3.51 m (11.5 ft) NW of the NW face of a wood bulkhead along the beach area.
The bench mark is set 6 cm (0.2 ft) below ground level, crimped to the top of a
galvanized steel rod driven 15.2 m (50 ft) to refusal, and encased in PVC pipe
and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8534836 PUBLICATION DATE: 05/12/2004
Name: LONGPORT, RISELY CHANNEL
NJ
NOAA Chart: 12316 Latitude: 39° 18.5' N ( 39.30830)
USGS Quad: OCEAN CITY Longitude: 74° 32.0' W ( -74.53330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4836 G 1977
DESIGNATION: 853 4836 G TIDAL
MONUMENTATION: Tidal Station disk VM#: 2738
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Galvanized steel rod OPUS PID:
LATITUDE: 39° 18.5' N ( 39.30830) LONGITUDE: 74° 32.0' W ( -74.53330)
The bench mark is a disk located 97.57 m (320.1 ft) SW of bench mark 4836 F
1977, 22.71 m (74.5 ft) south of the intersection of the centerlines of 15th
Street and Beach Avenue, 8.66 m (28.4 ft) SE of the centerline of Beach Avenue,
3.75 m (12.3 ft) NW of the corner of the bulkhead, and 3 m (10 ft) west of the
west face of the wood bulkhead bordering the beach area. The bench mark is set
6 cm (0.2 ft) below ground level, crimped to the top of a galvanized steel rod
driven 15.2 m (50 ft) to refusal, and encased in PVC pipe and concrete
kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8534836 PUBLICATION DATE: 05/12/2004
Name: LONGPORT, RISELY CHANNEL
NJ
NOAA Chart: 12316 Latitude: 39° 18.5' N ( 39.30830)
USGS Quad: OCEAN CITY Longitude: 74° 32.0' W ( -74.53330)
T I D A L D A T U M S
Tidal datums at LONGPORT, RISELY CHANNEL based on:
LENGTH OF SERIES: 1 YEAR
TIME PERIOD: June 1977 - May 1978
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8557380 LEWES, FT. MILES
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (10/14/1977) = 2.231
MEAN HIGHER HIGH WATER MHHW = 1.320
MEAN HIGH WATER MHW = 1.197
MEAN TIDE LEVEL MTL = 0.621
MEAN SEA LEVEL MSL = 0.619
MEAN LOW WATER MLW = 0.045
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (03/07/1978) = -0.759
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
NO 9 1962 2.284 1.087
4836 E 1977 2.649 1.452
4836 F 1977 2.695 1.498
4836 G 1977 2.851 1.654
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8534836 PUBLICATION DATE: 05/12/2004
Name: LONGPORT, RISELY CHANNEL
NJ
NOAA Chart: 12316 Latitude: 39° 18.5' N ( 39.30830)
USGS Quad: OCEAN CITY Longitude: 74° 32.0' W ( -74.53330)
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.