U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 4
PUBLICATION DATE: 07/01/1985
Station ID: 8720434 SUPERCEDED DATE: 04/21/2003
Name: SEABOARD COASTLINE RAILROAD BRIDGE, BLACK CREEK
FLORIDA
NOAA Chart: 11492 Latitude: 30° 4.8' N
USGS Quad: MIDDLEBURG Longitude: 81° 45.7' W
To reach the tidal bench marks from the intersection of U.S. Route 17 and
Kingsley Avenue in Orange Park, proceed south on U.S. Route 17 for 4.5 miles
(7.2 km) to its intersection with Florida State Route 220, go west on Florida
State Route 220 for 3.8 miles (6.1 km) to Sleepy Hollow Road, drive south on
Sleepy Hollow Road which becomes a dirt road after 0.4 mile (0.6 km) until it
intersects another dirt road after 1.2 miles (1.9 km), then go south 0.2 mile
(0.3 km) on this dirt road (which is east of the main dirt road) until it
reaches Black Creek. The bench marks are along the roads leading to the river
from Florida State Route 220, and the tide gage and staff were 130 feet (40 m)
east of the Seaboard Coastline Railroad Bridge which crosses over Black Creek.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 0434 A 1978
MONUMENTATION: Survey Disk VM#: 5187
AGENCY: PID#: BC1462
SETTING CLASSIFICATION: Concrete Bridge Footing
The bench mark is set in a concrete bridge footing 120 feet (37 m) west of the
railroad bridge, 31 feet (9 m) SW of the centerline of the dirt road leading to
the gage site, 17 feet (5 m) NE of a cypress tree, and 8 feet (2 m) north of the
north shoreline of Black Creek.
BENCH MARK STAMPING: 0434 B 1978
MONUMENTATION: Survey Disk VM#: 5188
AGENCY: PID#: BC1461
SETTING CLASSIFICATION: Concrete Post
The bench mark is set on a concrete post 12 feet (4 m) above the dirt road, 264
feet (80 m) south of the intersection of Sleepy Hollow Road and the secondary
dirt road, 100 feet (30 m) west of the railroad tracks, 30 feet (9 m) NW of the
fourth telephone pole from the north bank of the creek, 29 feet (9 m) east of
the centerline of the dirt road, and 1 foot (0.3 m) east of a witness post.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 4
PUBLICATION DATE: 07/01/1985
Station ID: 8720434 SUPERCEDED DATE: 04/21/2003
Name: SEABOARD COASTLINE RAILROAD BRIDGE, BLACK CREEK
FLORIDA
NOAA Chart: 11492 Latitude: 30° 4.8' N
USGS Quad: MIDDLEBURG Longitude: 81° 45.7' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 0434 C 1978
MONUMENTATION: Survey Disk VM#: 5189
AGENCY: PID#: BC1460
SETTING CLASSIFICATION: Copper-clad Steel Rod
The bench mark is 125 feet (38 m) west of the west rail of the railroad tracks,
47 feet (14 m) west of the dirt road leading to the gage site, 18 feet (5 m) SE
of the fifth telephone pole north of the gage site, and 1 foot (0.3 m) east of a
witness post. The bench mark is crimped to the top of a copper-clad steel rod
driven 32 feet (10 m), and is about level with the ground.
BENCH MARK STAMPING: 0434 D 1978
MONUMENTATION: Survey Disk VM#: 5190
AGENCY: PID#: BC1459
SETTING CLASSIFICATION: Concrete Post
The bench mark is 528 feet (161 m) NW of Bench Mark 0434 C 1978, 200 feet (61 m)
west of the railroad tracks, 88 feet (27 m) NW of a telephone pole, 22 feet (7
m) west of the centerline of Sleepy Hollow Road, and 1 foot (0.3 m) east of a
witness post on a concrete post.
BENCH MARK STAMPING: 0434 E 1978
MONUMENTATION: Survey Disk VM#: 5191
AGENCY: PID#: BC1458
SETTING CLASSIFICATION: Copper-clad Steel Rod
The bench mark is 0.5 miles (0.8 km) north of Bench Mark 0434 D 1978, 22 feet (7
m) east of the centerline of Sleepy Hollow Road, 5 feet (2 m) east of a witness
post, and 4.5 feet (1 m) east of a telephone pole. The bench mark is crimped to
the top of a copper-clad steel rod driven to a depth of 32 feet (10 m), and is
about level with the road.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 4
PUBLICATION DATE: 07/01/1985
Station ID: 8720434 SUPERCEDED DATE: 04/21/2003
Name: SEABOARD COASTLINE RAILROAD BRIDGE, BLACK CREEK
FLORIDA
NOAA Chart: 11492 Latitude: 30° 4.8' N
USGS Quad: MIDDLEBURG Longitude: 81° 45.7' W
T I D A L D A T U M S
Tidal datums at SEABOARD COASTLINE RAILROAD BRIDGE, BLACK CREEK based on:
LENGTH OF SERIES: 3 MONTHS
TIME PERIOD: AUGUST-OCTOBER 1978
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8720496 GREEN COVE SPRINGS,
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (06/16/1978) = 2.33
MEAN HIGHER HIGH WATER MHHW = 0.92
MEAN HIGH WATER MHW = 0.87
MEAN TIDE LEVEL MTL = 0.46
MEAN LOW WATER MLW = 0.05
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (07/31/1978) = -0.76
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
0434 A 1978 6.13 5.26
0434 B 1978 16.97 16.10
0434 C 1978 15.99 15.12
0434 D 1978 14.80 13.93
0434 E 1978 15.81 14.94
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 4
PUBLICATION DATE: 07/01/1985
Station ID: 8720434 SUPERCEDED DATE: 04/21/2003
Name: SEABOARD COASTLINE RAILROAD BRIDGE, BLACK CREEK
FLORIDA
NOAA Chart: 11492 Latitude: 30° 4.8' N
USGS Quad: MIDDLEBURG Longitude: 81° 45.7' 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.