U.S. DEPARTMENT OF COMMERCE
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National Ocean Service
Datums Page Page 1 of 7
Station ID: 8761473 PUBLICATION DATE: 09/18/2015
Name: RT. 433, BAYOU BONFOUCA
LA
NOAA Chart: 11369 Latitude: 30° 16.3' N ( 30.27170)
USGS Quad: SLIDELL Longitude: 89° 47.6' W ( -89.79330)
To reach the tidal bench marks from the intersection of U.S. Highway 11 and
State Route 433 in Slidell, proceed west on State Route 433 for 0.6 km (0.4 mi)
to the highway bridge over Bayou Bonfouca. The bench marks are located along
the highway east of the bridge. The tide gage and staff were located on the
bridge fender just south of the south edge of the bridge.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: WES 35 1978
DESIGNATION: 876 1473 WES 35
MONUMENTATION: Survey disk VM#: 15134
AGENCY: US Army Corps of Engineers (USE) IDB PID#:
SETTING CLASSIFICATION: Concrete pier OPUS PID:
LATITUDE: 30° 16.3' N ( 30.27170) LONGITUDE: 89° 47.6' W ( -89.79330)
The primary bench mark is a disk set in the top of the first concrete pier west
of the east end of the State Route 433 swing bridge over Bayou Bonfouca, on the
east side of bayou Bonfouca, 30 m (99 ft) north of a power pole with underground
cables, 25.97 m (85.2 ft) NE of the NW corner of the bridge fender's building,
4.02 m (13.2 ft) west of a witness post and sign, and 1.71 m (5.6 ft) east of
the SW corner of the concrete bridge pier.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 7
Station ID: 8761473 PUBLICATION DATE: 09/18/2015
Name: RT. 433, BAYOU BONFOUCA
LA
NOAA Chart: 11369 Latitude: 30° 16.3' N ( 30.27170)
USGS Quad: SLIDELL Longitude: 89° 47.6' W ( -89.79330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1473 D 1982
DESIGNATION: 876 1473 D
MONUMENTATION: Tidal Station disk VM#: 11027
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 30° 16.3' N ( 30.27170) LONGITUDE: 89° 47.6' W ( -89.79330)
The bench mark is a disk located 73 m (240 ft) south of bench mark 1473 C 1982,
25 m (83 ft) west of light pole #87, 20 m (66 ft) SW of the centerline of Route
433, 6 m (21 ft) SE of the SE corner of a 2 m (6 ft) high chain link fence
surrounding a vocational school, and 2 m (5 ft) SE of power pole #365. The
bench mark is set 9 cm (0.3 ft) below ground level, crimped to the top of a
stainless steel rod driven 14.6 m (48 ft) to refusal, and encased in a 4-inch
PVC pipe and concrete kickblock.
BENCH MARK STAMPING: 1473 A 1982
DESIGNATION: 876 1473 A
MONUMENTATION: Tidal Station disk VM#: 11210
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 30° 16.3' N ( 30.27170) LONGITUDE: 89° 47.6' W ( -89.79330)
The bench mark is a disk located 98 m (323 ft) SSE of bench mark WES 35 1978, 42
m (137 ft) WNW of light pole #91A, 13 m (44 ft) SW of the centerline of State
Route 433, 7 m (23 ft) south of the centerline of an abandoned railroad spur,
and 7 m (22 ft) north of power pole #375. The bench mark is set 9 cm (0.3 ft)
below ground level, crimped to the top of a stainless steel rod driven 17.1 m
(56 ft) to substantial resistance, 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 7
Station ID: 8761473 PUBLICATION DATE: 09/18/2015
Name: RT. 433, BAYOU BONFOUCA
LA
NOAA Chart: 11369 Latitude: 30° 16.3' N ( 30.27170)
USGS Quad: SLIDELL Longitude: 89° 47.6' W ( -89.79330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: W 20 1934
DESIGNATION: W 20
MONUMENTATION: Bench Mark disk VM#: 11211
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: BH1254
SETTING CLASSIFICATION: Concrete foundation OPUS PID:
LATITUDE: 30° 16.6' N ( 30.27670) LONGITUDE: 89° 46.9' W ( -89.78170)
The bench mark is a disk set in the top of the west corner of the concrete
foundation for the NW leg of an abandoned water tower, located at the City Hall
on First Street in Slidell.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 7
Station ID: 8761473 PUBLICATION DATE: 09/18/2015
Name: RT. 433, BAYOU BONFOUCA
LA
NOAA Chart: 11369 Latitude: 30° 16.3' N ( 30.27170)
USGS Quad: SLIDELL Longitude: 89° 47.6' W ( -89.79330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: V 20 1934
DESIGNATION: V 20
MONUMENTATION: Bench Mark disk VM#: 11212
AGENCY: US Coast and Geodetic Survey
(USC&GS) IDB PID#: BH1253
SETTING CLASSIFICATION: Concrete foundation OPUS PID:
LATITUDE: 30° 16.4' N ( 30.27330) LONGITUDE: 89° 47.1' W ( -89.78500)
The bench mark is a disk set in the top of the concrete foundation ledge of the
Masonic Temple in Slidell, 4 m (12 ft) north of the west entrance, 1 m (4 ft)
south of the NW corner of the temple, and 0.3 m (1 ft) south of the cornerstone.
BENCH MARK STAMPING: 1473 B 1982
DESIGNATION: 876 1473 B
MONUMENTATION: Tidal Station disk VM#: 15132
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 30° 16.3' N ( 30.27170) LONGITUDE: 89° 47.6' W ( -89.79330)
The bench mark is a disk located 65 m (214 ft) SE of bench mark 1473 A 1982, 27
m (90 ft) NW of power pole #91A, 21 m (68 ft) NNW of the centerline of Canulette
Road, and 15 m (49 ft) SW of the centerline of Route 433. The bench mark is set
9 cm (0.3 ft) below ground level, crimped to the top of a stainless steel rod
driven 15.5 m (51 ft) 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 5 of 7
Station ID: 8761473 PUBLICATION DATE: 09/18/2015
Name: RT. 433, BAYOU BONFOUCA
LA
NOAA Chart: 11369 Latitude: 30° 16.3' N ( 30.27170)
USGS Quad: SLIDELL Longitude: 89° 47.6' W ( -89.79330)
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 1473 C 1982
DESIGNATION: 876 1473 C
MONUMENTATION: Tidal Station disk VM#: 15133
AGENCY: National Ocean Survey (NOS) IDB PID#:
SETTING CLASSIFICATION: Stainless steel rod OPUS PID:
LATITUDE: 30° 16.3' N ( 30.27170) LONGITUDE: 89° 47.6' W ( -89.79330)
The bench mark is a disk located 69 m (226 ft) ESE of bench mark 1473 B 1982, 68
m (223 ft) SW of Gulf Outlet Marine Services warehouse, 42 m (137 ft) NW of
light pole #88, 23 m (74 ft) NE of light pole #89A, and 14 m (45 ft) NE of the
centerline of Route 433. The bench mark is set 9 cm (0.3 ft) below ground
level, crimped to the top of a stainless steel rod driven 17.1 m (56 ft) to
substantial resistance, 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 6 of 7
Station ID: 8761473 PUBLICATION DATE: 09/18/2015
Name: RT. 433, BAYOU BONFOUCA
LA
NOAA Chart: 11369 Latitude: 30° 16.3' N ( 30.27170)
USGS Quad: SLIDELL Longitude: 89° 47.6' W ( -89.79330)
T I D A L D A T U M S
Tidal datums at RT. 433, BAYOU BONFOUCA based on:
LENGTH OF SERIES: 5 YEARS
TIME PERIOD: June 1983 - May 1988
TIDAL EPOCH: 1983-2001
CONTROL TIDE STATION: 8747437 BAY WAVELAND YACHT CLUB, BAY ST. LOUIS
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS:
HIGHEST OBSERVED WATER LEVEL (10/29/1985) = 1.423
MEAN HIGHER HIGH WATER MHHW = 0.162
MEAN HIGH WATER MHW = 0.160
MEAN SEA LEVEL MSL = 0.084
MEAN TIDE LEVEL MTL = 0.080
MEAN LOW WATER MLW = 0.000
MEAN LOWER LOW WATER MLLW = 0.000
LOWEST OBSERVED WATER LEVEL (04/13/1988) = -0.720
North American Vertical Datum (NAVD88)
Bench Mark Elevation Information In METERS above:
Stamping or Designation MLLW MHW
WES 35 1978 1.849 1.689
1473 D 1982 1.117 0.957
1473 A 1982 0.613 0.453
W 20 1934 2.649 2.489
V 20 1934 2.077 1.917
1473 B 1982 1.096 0.936
1473 C 1982 1.019 0.859
Foot Notes:
Bench marks V 20 1934 and W 20 1934 are based on one differential leveling
connection and do not meet the quality control standards of the NOS. Therefore,
caution should be used when deriving elevations for these marks.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 7 of 7
Station ID: 8761473 PUBLICATION DATE: 09/18/2015
Name: RT. 433, BAYOU BONFOUCA
LA
NOAA Chart: 11369 Latitude: 30° 16.3' N ( 30.27170)
USGS Quad: SLIDELL Longitude: 89° 47.6' W ( -89.79330)
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.