Published Bench Mark Sheet for 8724979 STATE ROAD 92, BIG MARCO RIVER FLORIDA
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
PUBLICATION DATE: 03/28/1988
Station ID: 8724979 SUPERCEDED DATE: 04/21/2003
Name: STATE ROAD 92, BIG MARCO RIVER
FLORIDA
NOAA Chart: 11429 Latitude: 25° 56.0' N
USGS Quad: MARCO ISLAND Longitude: 81° 39.3' W
To reach the tidal bench marks from the intersection of U.S. Highway 41 and
State Road 92 proceed west on State Road 92 for 6.4 miles (10.3 km) (over Big
Marco River) to Ship Ahoy Marina. The bench marks are located in the area
around Ship Ahoy Marina and to the east. The tide gage and staff were located
on the Ship Ahoy Marina Pier.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 4979 A 1978
MONUMENTATION: Survey Disk VM#: 9753
AGENCY: PID#: AC3392
SETTING CLASSIFICATION: Concrete Sea Wall
The bench mark is set in the concrete sea wall on the east side of the Ship Ahoy
Marina boat ramp, 28.0 feet (8.5 m) SE of the NE corner of Ship Ahoy Marina, 22
feet (7 m) SE of the base of an old Union 76 sign, and 20.9 feet (6.4 m) east of
Bench Mark 4979 B 1978.
BENCH MARK STAMPING: 4979 B 1978
MONUMENTATION: Survey Disk VM#: 9754
AGENCY: PID#: AC3393
SETTING CLASSIFICATION: Concrete Sea Wall
The bench mark is set flush in the concrete sea wall on the west side of the
Ship Ahoy Marina boat ramp, 21.9 feet (6.7 m) south of the base of an old Union
76 sign, and 16.9 feet (5.2 m) SSE of the NE corner of the tackle shop.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
PUBLICATION DATE: 03/28/1988
Station ID: 8724979 SUPERCEDED DATE: 04/21/2003
Name: STATE ROAD 92, BIG MARCO RIVER
FLORIDA
NOAA Chart: 11429 Latitude: 25° 56.0' N
USGS Quad: MARCO ISLAND Longitude: 81° 39.3' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4979 C 1978
MONUMENTATION: Survey Disk VM#: 9755
AGENCY: PID#: AC3395
SETTING CLASSIFICATION: Galvanized Steel Rod
The bench mark is under the west end of the State Road 92 bridge over Big Marco
River, 200 feet (61 m) west of Bench Mark 4979 F 1978, 26.1 feet (8.0 m) east of
the centerline of a paved road (under the bridge) that leads to Ship Ahoy
Marina, 1 foot (0.3 m) south of the south piling of the westernmost group of
pilings supporting the bridge, and 1 foot (0.3 m) south of a witness post. The
bench mark is crimped to a galvanized steel rod driven 24 feet (7 m) to refusal,
and encased in a 4-inch PVC pipe and concrete kickblock.
BENCH MARK STAMPING: 4979 E 1978
MONUMENTATION: Survey Disk VM#: 9756
AGENCY: PID#: AC3396
SETTING CLASSIFICATION: Galvanized Steel Rod
The bench mark is located 200 feet (61 m) south of the State Road 92 bridge over
Big Marco River, 87 feet (27 m) SE of the junction of the drive to the Ship Ahoy
Marina and County Road 892 (Goodland Road), 39.1 feet (11.9 m) south of a
concrete power pole, 3 feet (1 m) east of a small monument to old Goodland Road,
and 1.5 feet (0.5 m) east of a witness post. The bench mark is 0.3 foot (0.1 m)
below the gravel around monument, crimped to a galvanized steel rod driven 22
feet (7 m) to refusal, and encased in a 4-inch PVC pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
PUBLICATION DATE: 03/28/1988
Station ID: 8724979 SUPERCEDED DATE: 04/21/2003
Name: STATE ROAD 92, BIG MARCO RIVER
FLORIDA
NOAA Chart: 11429 Latitude: 25° 56.0' N
USGS Quad: MARCO ISLAND Longitude: 81° 39.3' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 4979 F 1978
MONUMENTATION: Survey Disk VM#: 9757
AGENCY: PID#: AC3394
SETTING CLASSIFICATION: Bridge Pier Foundation
The bench mark is under the State Road 92 bridge over Big Marco River, set in
the SW corner of the base of the westernmost concrete bridge pier that is in the
water, 58.5 feet (17.8 m) north of the north side of the old wooden bridge and 2
feet (1 m) above the approximate high water mark.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
PUBLICATION DATE: 03/28/1988
Station ID: 8724979 SUPERCEDED DATE: 04/21/2003
Name: STATE ROAD 92, BIG MARCO RIVER
FLORIDA
NOAA Chart: 11429 Latitude: 25° 56.0' N
USGS Quad: MARCO ISLAND Longitude: 81° 39.3' W
T I D A L D A T U M S
Tidal datums at STATE ROAD 92, BIG MARCO RIVER based on:
LENGTH OF SERIES: 5 MONTHS
TIME PERIOD: MARCH-JULY 1978
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8724967 MARCO ISLAND
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (05/04/1978) = 4.39
MEAN HIGHER HIGH WATER (MHHW) = 3.42
MEAN HIGH WATER (MHW) = 3.18
MEAN TIDE LEVEL (MTL) = 1.86
MEAN LOW WATER (MLW) = 0.53
MEAN LOWER LOW WATER (MLLW) = 0.00
LOWEST OBSERVED WATER LEVEL (03/19/1978) = -0.91
National Geodetic Vertical Datum (NGVD 29)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
4979 A 1978 5.02 1.84
4979 B 1978 5.30 2.12
4979 C 1978 7.92 4.74
4979 E 1978 5.55 2.37
4979 F 1978 5.31 2.13
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
PUBLICATION DATE: 03/28/1988
Station ID: 8724979 SUPERCEDED DATE: 04/21/2003
Name: STATE ROAD 92, BIG MARCO RIVER
FLORIDA
NOAA Chart: 11429 Latitude: 25° 56.0' N
USGS Quad: MARCO ISLAND Longitude: 81° 39.3' 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 (NAVD 88).
NGVD 29 is a fixed datum adopted as a national standard geodetic reference for
heights but is now considered superseded. NGVD 29 is sometimes referred to as
Sea Level Datum of 1929 or as Mean Sea Level on some early issues of Geological
Survey Topographic Quads. NGVD 29 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 NGVD 29 are available from the National
Geodetic Survey (NGS) data base via the World Wide Web at
National Geodetic Survey.
NAVD 88 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. NAVD 88 replaces NGVD 29 as the national
standard geodetic reference for heights. Bench mark elevations relative to
NAVD 88 are available from NGS through the World Wide Web at
National Geodetic Survey.
NGVD 29 and NAVD 88 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 NAVD 88 elevation is shown on the Elevations of Tidal Datums Table Referred
to MLLW only when two or more of the bench marks listed have NAVD 88 elevations.
The NAVD 88 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, NAVD 88 bench mark elevations computed indirectly from the tidal
datums elevation table may differ slightly from NAVD 88 elevations listed for
each bench mark in the NGS database.
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