Superseded Bench Mark Sheet for 8570649, PUBLIC LANDING, CHINCOTEAGUE BAY MD

Present Epoch

Printable version

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  4

                                                   PUBLICATION DATE:  04/05/1990
Station ID: 8570649                                SUPERCEDED DATE:   04/21/2003
Name:       PUBLIC LANDING, CHINCOTEAGUE BAY                  
            MARYLAND
NOAA Chart: 12211                                  Latitude:         38°  8.9' N
USGS Quad:  PUBLIC LANDING                         Longitude:        75° 17.1' W


To reach the tidal bench marks from the intersection of U.S. Highway 113 and
State Highway 365 in Snowhill, proceed east on State Highway 365 for 5.3 miles 
(8.5 km) to the public landing.  The bench marks are near the county pier.  The
tide gage and staff were on the east end and south side of the pier.


                         T I D A L   B E N C H   M A R K S


                 PRIMARY BENCH MARK STAMPING:  0649 A 1985

MONUMENTATION:           Survey Disk                               VM#:     3034
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Step


The bench mark is set flush in the bottom concrete step on the south side of the
Driscoll residence, 37.3 feet (11.4 m) SE of the extended centerline of Bayside
Road, 27.3 feet (8.3 m) NW of a 2.0-foot (0.6 m) diameter cedar tree, and 25.3
feet (7.7 m) NE of the centerline of State Highway 365.



                         BENCH MARK STAMPING:  18 WDK 1963 RESET 1976

MONUMENTATION:           Survey Disk                               VM#:     3033
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Footing/Base of Large Pole


The bench mark is set flush in the 2.0-foot (0.6 m) square concrete base of an
abandoned pole, 153 feet (47 m) NW of the centerline of Bayside Road, 21.7 feet
(6.6 m) SW of the centerline of State Highway 365, and 4.0 feet (1.2 m) east of
power pole #163.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  4

                                                   PUBLICATION DATE:  04/05/1990
Station ID: 8570649                                SUPERCEDED DATE:   04/21/2003
Name:       PUBLIC LANDING, CHINCOTEAGUE BAY                  
            MARYLAND
NOAA Chart: 12211                                  Latitude:         38°  8.9' N
USGS Quad:  PUBLIC LANDING                         Longitude:        75° 17.1' W


                         T I D A L   B E N C H   M A R K S


                         BENCH MARK STAMPING:  0649 B 1985

MONUMENTATION:           Survey Disk                               VM#:     3035
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Base


The bench mark is set in the top of a concrete pedestal of an abandoned fuel
storage tank, 43 feet (13 m) NW of the centerline of Bayside Road, 26.0 feet
(7.9 m) SW of the centerline of State Highway 365, and 18 feet (5 m) NE of the
SE corner of a 2-story frame dwelling.



                         BENCH MARK STAMPING:  0649 C 1985

MONUMENTATION:           Survey Disk                               VM#:     3036
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Stainless Steel Rod


The bench mark is 91.0 feet (27.7 m) NW of the centerline of a paved road, 39.0
feet (11.9 m) NE of the centerline of State Highway 365, and 2.3 feet (0.7 m) SW
of power pole #120 with witness post.  The bench mark is 0.5 foot (0.2 m) below
ground level, crimped to a stainless steel rod driven an unspecified depth, and
encased in a 5-inch PVC pipe and concrete kickblock.



                         BENCH MARK STAMPING:  0649 D 1985

MONUMENTATION:           Survey Disk                               VM#:     3037
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Stainless Steel Rod


The bench mark is 171.5 feet (52.3 m) NW of power pole #118, 154.7 feet (47.2 m)
SE of power pole #117, 104.0 feet (31.7 m) NE of the north corner of a 2-story
frame dwelling (Hamaker's residence), and 34.5 feet (10.5 m) NE of the center-
line of State Highway 365.  The bench mark is 0.5 foot (0.2 m) below the
surface, crimped to a stainless steel rod driven 32 feet (10 m), and encased in
a 5-inch PVC pipe and concrete kickblock.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  4

                                                   PUBLICATION DATE:  04/05/1990
Station ID: 8570649                                SUPERCEDED DATE:   04/21/2003
Name:       PUBLIC LANDING, CHINCOTEAGUE BAY                  
            MARYLAND
NOAA Chart: 12211                                  Latitude:         38°  8.9' N
USGS Quad:  PUBLIC LANDING                         Longitude:        75° 17.1' W


                            T I D A L   D A T U M S 


Tidal datums at PUBLIC LANDING, CHINCOTEAGUE BAY based on:

     LENGTH OF SERIES:      3 MONTHS
     TIME PERIOD:           AUGUST - OCTOBER 1985
     TIDAL EPOCH:           1960-1978
     CONTROL TIDE STATION:  8558690 INDIAN RIVER, DE


Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:

     HIGHEST OBSERVED WATER LEVEL (11/05/1985)         =   2.76
     MEAN HIGHER HIGH WATER                     MHHW   =   0.73
     MEAN HIGH WATER                            MHW    =   0.65
     MEAN TIDE LEVEL                            MTL    =   0.39
     MEAN LOW WATER                             MLW    =   0.13
     MEAN LOWER LOW WATER                       MLLW   =   0.00
     LOWEST  OBSERVED WATER LEVEL (10/20/1985)         =  -0.16



Bench Mark Elevation Information                In FEET above:

     Stamping or Designation                    MLLW        MHW

     0649 A 1985                                10.63      9.98
     18 WDK 1963 RESET 1976                      9.96      9.31
     0649 B 1985                                 9.74      9.09
     0649 C 1985                                11.80     11.15
     0649 D 1985                                13.41     12.76


                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  4

                                                   PUBLICATION DATE:  04/05/1990
Station ID: 8570649                                SUPERCEDED DATE:   04/21/2003
Name:       PUBLIC LANDING, CHINCOTEAGUE BAY                  
            MARYLAND
NOAA Chart: 12211                                  Latitude:         38°  8.9' N
USGS Quad:  PUBLIC LANDING                         Longitude:        75° 17.1' 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.

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