Superseded Bench Mark Sheet for 8636580, Windmill Point VA

Present Epoch

Printable version

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  5

                                                   PUBLICATION DATE:  02/09/1986
Station ID: 8636580                                SUPERCEDED DATE:   04/21/2003
Name:       WINDMILL MARINA, RAPPAHANNOCK RIVER               
            VIRGINIA
NOAA Chart: 12235                                  Latitude:         37° 36.9' N
USGS Quad:  DELTAVILLE                             Longitude:        76° 17.6' W


To reach the tidal bench marks from the town of Whitestone, Virginia, at the
junction of State Highways 3 and 200, proceed SE on County Route 695 for 7.3
miles (11.7 km) to the dead end.  The bench marks are in the area between the
Exxon Station and the pier.  The tide gage and staff were located on the end of
the pier.


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


                 PRIMARY BENCH MARK STAMPING:  NO 2 1970

MONUMENTATION:           Survey Disk                               VM#:    11254
AGENCY:                                                            PID#:  GV0088
SETTING CLASSIFICATION:  Concrete Foundation


The bench mark is located on the NE footing supporting the Exxon sign on the
Windmill Point Marina property, and set on a drill hole in the top of the center
of the foundation.



                         BENCH MARK STAMPING:  6580 A 1982

MONUMENTATION:           Survey Disk                               VM#:    11255
AGENCY:                                                            PID#:  GV6186
SETTING CLASSIFICATION:  Unspecified Rod


The bench mark is located 173 feet (53 m) south of the southernmost corner of a
row of four townhouses, 70 feet (21 m) ESE of the centerline of County Route 695
at the end of the road, 32.5 feet (9.9 m) NE of the easternmost corner of the
pier at the end of the state road, and 0.2 foot (0.06 m) west of an orange
witness post.  The bench mark is 0.3 foot (0.09 m) below ground, crimped to the
top of an unspecified rod driven to refusal at 50 feet (15 m), and encased in a
PVC pipe extending 0.4 foot (0.1 m) above ground level.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  5

                                                   PUBLICATION DATE:  02/09/1986
Station ID: 8636580                                SUPERCEDED DATE:   04/21/2003
Name:       WINDMILL MARINA, RAPPAHANNOCK RIVER               
            VIRGINIA
NOAA Chart: 12235                                  Latitude:         37° 36.9' N
USGS Quad:  DELTAVILLE                             Longitude:        76° 17.6' W


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


                         BENCH MARK STAMPING:  6580 B 1982

MONUMENTATION:           Survey Disk                               VM#:    11256
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Unspecified Rod


The bench mark is located 332 feet (101 m) north of Bench Mark 6580 A 1982, 120
feet (37 m) NE of the northeasternmost corner of a row of townhouses, 68 feet
(21 m) NNW of the centerline of County Route 695, 22 feet (6.7 m) NW of
telephone pole #631F88, and 0.7 foot (0.06 m) SE of an orange witness post. The
bench mark is 0.3 foot (0.09 m) below ground, crimped to the top of an
unspecified rod driven to refusal at 54 feet (16 m), and encased in a PVC pipe
extending 0.3 foot (0.09 m) above ground level.



                         BENCH MARK STAMPING:  6580 C 1982

MONUMENTATION:           Survey Disk                               VM#:    11257
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Unspecified Rod


The bench mark is located on the SE side of County Route 695 on the SSW side of
the first entrance road to the Windmill Point Marine Resort, 183 feet (56 m) NE
of Bench Mark 6580 B 1982, 103.4 feet (32 m) SSW of the southwesternmost corner
of a row of four townhouses on the SE side of County Route 695 just before the
entrance to the marine resort, 63.0 feet (19.2 m) SE of the centerline of County
Route 695, 50.0 feet (15.2 m) SSW of the centerline of the road leading to the
resort and 0.2 foot (0.06 m) NW of a witness post.  The bench mark is 0.3 foot
(0.09 m) below ground, crimped to the top of an unspecified rod driven to
refusal at 46 feet (14 m).

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  5

                                                   PUBLICATION DATE:  02/09/1986
Station ID: 8636580                                SUPERCEDED DATE:   04/21/2003
Name:       WINDMILL MARINA, RAPPAHANNOCK RIVER               
            VIRGINIA
NOAA Chart: 12235                                  Latitude:         37° 36.9' N
USGS Quad:  DELTAVILLE                             Longitude:        76° 17.6' W


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


                         BENCH MARK STAMPING:  6580 D 1982

MONUMENTATION:           Survey Disk                               VM#:    11258
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Unspecified Rod


The bench mark is located NE of the parking lot for the resort motel, 325 feet
(99 m) NE of Bench Mark 6580 B 1982 and in line with Bench Mark 6580 B 1982 and
Bench Mark 6580 A 1982, 197 feet (60 m) NNW of the center of the entrance door
to the motel lobby, 168 feet (51 m) SW of the westernmost support of the large
Exxon sign, 82 feet (25 m) NE of the parking blocks on the NE side of the motel
parking lot, and 0.1 foot (0.03 m) NW of the witness post.  The bench mark is
0.3 foot (0.09 m) below ground, crimped to the top of an unspecified rod driven
to refusal at 50 feet (15 m), and encased in a PVC pipe extending 0.3 foot (0.09
m) above ground level.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  5

                                                   PUBLICATION DATE:  02/09/1986
Station ID: 8636580                                SUPERCEDED DATE:   04/21/2003
Name:       WINDMILL MARINA, RAPPAHANNOCK RIVER               
            VIRGINIA
NOAA Chart: 12235                                  Latitude:         37° 36.9' N
USGS Quad:  DELTAVILLE                             Longitude:        76° 17.6' W


                            T I D A L   D A T U M S 


Tidal datums at WINDMILL MARINA, RAPPAHANNOCK RIVER based on:

     LENGTH OF SERIES:      4 MONTHS
     TIME PERIOD:           APRIL-AUGUST 1982
     TIDAL EPOCH:           1960-1978
     CONTROL TIDE STATION:  8635750 LEWISETTA


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

     HIGHEST OBSERVED WATER LEVEL (10/26/1983)         =   3.08
     MEAN HIGHER HIGH WATER                     MHHW   =   1.35
     MEAN HIGH WATER                            MHW    =   1.24
     MEAN TIDE LEVEL                            MTL    =   0.67
     MEAN LOW WATER                             MLW    =   0.10
     MEAN LOWER LOW WATER                       MLLW   =   0.00
     LOWEST  OBSERVED WATER LEVEL (04/29/1982)         =  -1.19

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In FEET above:

     Stamping or Designation                    MLLW        MHW

     NO 2 1970                                   5.50      4.26
     6580 A 1982                                 6.25      5.01
     6580 B 1982                                 4.06      2.82
     6580 C 1982                                 3.53      2.29
     6580 D 1982                                 5.33      4.09


                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  5

                                                   PUBLICATION DATE:  02/09/1986
Station ID: 8636580                                SUPERCEDED DATE:   04/21/2003
Name:       WINDMILL MARINA, RAPPAHANNOCK RIVER               
            VIRGINIA
NOAA Chart: 12235                                  Latitude:         37° 36.9' N
USGS Quad:  DELTAVILLE                             Longitude:        76° 17.6' 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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