U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
PUBLICATION DATE: 02/19/1986
Station ID: 8517811 SUPERCEDED DATE: 04/21/2003
Name: GRAVESEND BAY, NEW YORK HARBOR
NEW YORK
NOAA Chart: 12349 Latitude: 40° 35.4' N
USGS Quad: CONEY ISLAND Longitude: 73° 59.9' W
To reach the tidal bench marks from the Verrazano Bridge, take the Belt Parkway
East to Exit 5 (Bay Parkway). Proceed on the Bay Parkway to the Shore Parkway.
Continue 0.55 mile (0.9 km) on the Shore Parkway to 41st Street, bear right and
continue 0.2 mile (0.3 km) to the Department of Sanitation, City of New York,
Southwest Brooklyn Marine Transfer Station pier located at the foot of 41st
Street and Gravesend Bay. The bench marks are located in the vicinity of the
pier. The tide gage and staff were located on the inside corner of the wooden
pier extension.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 7811 A 1979
MONUMENTATION: Survey Disk VM#: 2334
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is located on the property of the Department of Sanitation, City
of New York, Southwest Brooklyn Marine Transfer Station pier, set in the NW
corner of a 5-foot (1.5 m) x 6-foot (1.8 m) concrete base of a small capstan, 79
feet (24 m) from the corner of the red brick building along the seawall, and 25
feet (8 m) north of a fire hydrant.
BENCH MARK STAMPING: 7811 B 1979
MONUMENTATION: Survey Disk VM#: 2335
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Foundation
The bench mark is located at the Southwest Brooklyn Marine Transfer Station, set
in concrete base of a gray silo shaped incinerator, 92 feet (28 m) from the
seawall and 36 feet (11 m) from the doorway of the yellow brick building.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
PUBLICATION DATE: 02/19/1986
Station ID: 8517811 SUPERCEDED DATE: 04/21/2003
Name: GRAVESEND BAY, NEW YORK HARBOR
NEW YORK
NOAA Chart: 12349 Latitude: 40° 35.4' N
USGS Quad: CONEY ISLAND Longitude: 73° 59.9' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 7811 C 1979
MONUMENTATION: Survey Disk VM#: 2336
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Pad
The bench mark is located at the Southwest Brooklyn Marine Transfer Station, set
in the NE corner of a 10-foot (3 m) x 11-foot (3 m) concrete pad, 0.5 foot (0.2
m) from the SE corner of the red block building.
BENCH MARK STAMPING: 7811 D 1979
MONUMENTATION: Survey Disk VM#: 2337
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Base
The bench mark is located at the Southwest Brooklyn Marine Transfer Station, set
in concrete in the base of the entrance ramp of the red brick building, 62 feet
(19 m) north of the northeasternmost of two tall stacks at the point where the
ramp is above ground level.
BENCH MARK STAMPING: 7811 E 1979
MONUMENTATION: Survey Disk VM#: 2338
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Retaining Wall
The bench mark is located at the Southwest Brooklyn Marine Transfer Station, set
on the top of the SE end of the concrete entrance ramp retaining wall, set 3.7
feet (1.1 m) above the driveway.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
PUBLICATION DATE: 02/19/1986
Station ID: 8517811 SUPERCEDED DATE: 04/21/2003
Name: GRAVESEND BAY, NEW YORK HARBOR
NEW YORK
NOAA Chart: 12349 Latitude: 40° 35.4' N
USGS Quad: CONEY ISLAND Longitude: 73° 59.9' W
T I D A L D A T U M S
Tidal datums at GRAVESEND BAY, NEW YORK HARBOR based on:
LENGTH OF SERIES: 113 HIGH WATERS & LO
TIME PERIOD: SEPTEMBER 12-NOVEMBER 8, 1979
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8531680 SANDY HOOK, NJ
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (10/05/1979) = 7.58
MEAN HIGHER HIGH WATER MHHW = 5.31
MEAN HIGH WATER MHW = 4.97
MEAN TIDE LEVEL MTL = 2.60
MEAN LOW WATER MLW = 0.23
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (10/08/1979) = -2.08
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
7811 A 1979 11.01 6.04
7811 B 1979 13.23 8.26
7811 C 1979 11.02 6.05
7811 D 1979 11.92 6.95
7811 E 1979 14.42 9.45
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
PUBLICATION DATE: 02/19/1986
Station ID: 8517811 SUPERCEDED DATE: 04/21/2003
Name: GRAVESEND BAY, NEW YORK HARBOR
NEW YORK
NOAA Chart: 12349 Latitude: 40° 35.4' N
USGS Quad: CONEY ISLAND Longitude: 73° 59.9' W
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 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.