U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
Station ID: 8729791 PUBLICATION DATE: 05/20/2004
Name: HERNANDEZ POINT NORTH
FL
NOAA Chart: 11382 Latitude: 30° 27.3' N ( 30.45500)
USGS Quad: GARCON POINT Longitude: 87° 6.0' W ( -87.10000)
To reach the tidal bench marks from the interchange of Interstate Highway 10 and
County Road C-281 (Avalon Boulevard), south of Milton, proceed south along
County Road C-281 for 6.1 km (3.8 mi) to the junction of County Road C-191, then
proceed SW on County Road C-191 for 2.33 km (1.45 mi) to the dirt drive to the
Claude Smith residence, then turn right and proceed west along the drive for 0.6
km (0.4 mi) to the residence. The bench marks are along the dirt drive and
County Road C-191. The tide gage and staff were located on a pier in Escambia
Bay.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 9791 B 1977
DESIGNATION: 872 9791 B TIDAL
MONUMENTATION: Tidal Station disk VM#: 10235
AGENCY: National Ocean Survey (NOS) IDB PID#: BG3681
SETTING CLASSIFICATION: Galvanized steel rod OPUS PID:
LATITUDE: 30° 27.7' N ( 30.46170) LONGITUDE: 87° 5.8' W ( -87.09670)
The primary bench mark is located in a grassy area in a split between the dirt
drives, 100 m (328 ft) WNW of bench mark 9791 C 1977, 7 m (23 ft) NW of the
southmost dirt drive, 6.74 m (22.1 ft) SE of the northmost dirt drive, 2.13 m
(7.0 ft) west of a 0.46 m (1.5 ft) diameter pine tree, 6.40 m (21.0 ft) east of
a 0.55 m (1.8 ft) diameter pine tree, and 3 cm (1 ft) south of a witness post.
The bench mark is a disk set 3 cm (0.1 ft) below ground level, crimped to the
top of a galvanized steel rod driven 12.2 m (40 ft) to refusal, and encased in a
PVC pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
Station ID: 8729791 PUBLICATION DATE: 05/20/2004
Name: HERNANDEZ POINT NORTH
FL
NOAA Chart: 11382 Latitude: 30° 27.3' N ( 30.45500)
USGS Quad: GARCON POINT Longitude: 87° 6.0' W ( -87.10000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 9791 C 1977
DESIGNATION: 872 9791 C TIDAL
MONUMENTATION: Tidal Station disk VM#: 10236
AGENCY: National Ocean Survey (NOS) IDB PID#: BG3680
SETTING CLASSIFICATION: Galvanized steel rod OPUS PID:
LATITUDE: 30° 27.6' N ( 30.46000) LONGITUDE: 87° 5.8' W ( -87.09670)
The bench mark is located 218 m (714 ft) west of County Road C-191, 110 m (361
ft) WNW of bench mark 9791 D 1977, 100 m (328 ft) ESE of bench mark 9791 B 1977,
32.46 m (106.5 ft) SW of the dirt drive leading to the Smith residence, 6.10 m
(20.0 ft) west of a twin-trunked 0.46 m (1.5 ft) diameter oak tree, and 12 cm
(0.4 ft) north of a witness post. The bench mark is set at ground level,
crimped to the top of a galvanized steel rod driven 12.2 m (40 ft) and encased
in a PVC pipe and concrete kickblock.
BENCH MARK STAMPING: 9791 D 1977
DESIGNATION: 872 9791 D TIDAL
MONUMENTATION: Tidal Station disk VM#: 10237
AGENCY: National Ocean Survey (NOS) IDB PID#: BG3679
SETTING CLASSIFICATION: Galvanized steel rod OPUS PID:
LATITUDE: 30° 27.6' N ( 30.46000) LONGITUDE: 87° 5.7' W ( -87.09500)
The bench mark is located 139.9 m (459.0 ft) west of the centerline of County
Road C-191, 19.20 m (63.0 ft) south of the dirt drive, 1.83 m (6.0 ft) north of
a fence line, and 0.15 m (0.5 ft) ENE of a witness post. The bench mark is set
9 cm (0.3 ft) below ground level, crimped to the top of a galvanized steel rod
driven 12.2 m (40 ft), and encased in a PVC pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
Station ID: 8729791 PUBLICATION DATE: 05/20/2004
Name: HERNANDEZ POINT NORTH
FL
NOAA Chart: 11382 Latitude: 30° 27.3' N ( 30.45500)
USGS Quad: GARCON POINT Longitude: 87° 6.0' W ( -87.10000)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 9791 E 1977
DESIGNATION: 872 9791 E TIDAL
MONUMENTATION: Tidal Station disk VM#: 10238
AGENCY: National Ocean Survey (NOS) IDB PID#: BG3678
SETTING CLASSIFICATION: Concrete culvert head wall OPUS PID#: BG3678
LATITUDE: 30° 27.6' N ( 30.46000) LONGITUDE: 87° 5.6' W ( -87.09330)
The bench mark is a disk set in the top of a concrete culvert head wall, 69.13 m
(226.8 ft) NE of the driveway leading to the Smith's residence, and 5.64 m (18.5
ft) NW of the centerline of County Road C-191.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
Station ID: 8729791 PUBLICATION DATE: 05/20/2004
Name: HERNANDEZ POINT NORTH
FL
NOAA Chart: 11382 Latitude: 30° 27.3' N ( 30.45500)
USGS Quad: GARCON POINT Longitude: 87° 6.0' W ( -87.10000)
T I D A L D A T U M S
Tidal datums at HERNANDEZ POINT NORTH based on:
LENGTH OF SERIES: 2 MONTHS
TIME PERIOD: June 1977 - July 1977
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8729840 PENSACOLA, PENSACOLA BAY
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
MEAN HIGHER HIGH WATER MHHW = 0.397
MEAN HIGH WATER MHW = 0.380
MEAN TIDE LEVEL MTL = 0.204
MEAN SEA LEVEL MSL = 0.198
North American Vertical Datum NAVD88 = 0.104
MEAN LOW WATER MLW = 0.027
MEAN LOWER LOW WATER MLLW = 0.000
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
9791 B 1977 1.906 1.526
9791 C 1977 1.913 1.533
9791 D 1977 2.255 1.875
9791 E 1977 2.674 2.294
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
Station ID: 8729791 PUBLICATION DATE: 05/20/2004
Name: HERNANDEZ POINT NORTH
FL
NOAA Chart: 11382 Latitude: 30° 27.3' N ( 30.45500)
USGS Quad: GARCON POINT Longitude: 87° 6.0' W ( -87.10000)
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.