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Bench Mark Sheet for 8572669, Hillsboro MD

Superseded Epoch

Large map location marker Station Location
Small red map location marker Published bench mark
Small blue map location marker Unpublished bench mark

Bench mark positions only appear on the map if their coordinates in the CO-OPS database are at the precision of degrees/minutes/seconds/and tenths of seconds. If the coordinates are less precise, the mark will not appear.

Printable version

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  6

                                                                                
Station ID: 8572669                         PUBLICATION DATE:  04/22/2013
Name:       HILLSBORO, TUCKAHOE CREEK                         
            MD
NOAA Chart: 12268                           Latitude:   38° 55.0' N (  38.91670)
USGS Quad:  RIDGELY                         Longitude:  75° 56.7' W ( -75.94500)


From the intersection of 404 and 303 proceed south on 303 to ALT 404, proceed
east on ALT 404 approximately 2.4 km (1.5 mi) over the bridge and into Caroline
County.  The Hillsboro boat ramp is on the right, the gauge was located on the
seawall.  


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


                 PRIMARY BENCH MARK STAMPING:  2669 A 2005
                         DESIGNATION:          857 2669 A

MONUMENTATION:           Flange-encased Rod                    VM#:        17858
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod in sleeve         OPUS PID:        
LATITUDE:   38° 55.0' N (  38.91670)          LONGITUDE:  75° 56.7' W ( -75.94500)


The primary bench mark is a flange-encased rod located  in the county park north
east of the boat ramp, 17.98 m (59.0 ft) SE of the center of a large drain
culvert, 10.36 m (34.0 ft) NW of the entrance driveway into the park, 2.3 m (7.5
ft) SSW from the witness post, and 1.81 m (5.9 ft) SSW of phone pole
37154-13321.  The datum point is set flush with the ground, being the top of a
stainless steel rod driven 8.0 m (26.2 ft) to refusal, with a sleeve extending
0.9 m (3.0 ft) and encased in a 5-inch PVC pipe with a 5-inch NOS logo cap.  

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  6

                                                                                
Station ID: 8572669                         PUBLICATION DATE:  04/22/2013
Name:       HILLSBORO, TUCKAHOE CREEK                         
            MD
NOAA Chart: 12268                           Latitude:   38° 55.0' N (  38.91670)
USGS Quad:  RIDGELY                         Longitude:  75° 56.7' W ( -75.94500)


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


                         BENCH MARK STAMPING:  2669 B 2005
                         DESIGNATION:          857 2669 B

MONUMENTATION:           Tidal Station disk                    VM#:        17859
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Loading platform                      OPUS PID:        
LATITUDE:   38° 55.0' N (  38.91670)          LONGITUDE:  75° 56.9' W ( -75.94830)


The bench mark is a disk located on the Maryland  truck loading platform in the
southern corner,  36.48 m (119.7 ft) SSE of a power pole with transformers and
labeled "37064 13331", 10.30 m (33.8 ft) WSW of power pole "225",  0.35 m (1.2
ft) NNE of the loading dock wall.  



                         BENCH MARK STAMPING:  2669 C 2005
                         DESIGNATION:          857 2669 C

MONUMENTATION:           Tidal Station disk                    VM#:        17860
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Concrete abutment                     OPUS PID:        
LATITUDE:   38° 55.0' N (  38.91670)          LONGITUDE:  75° 56.7' W ( -75.94500)


The bench mark is a disk located on the eastern abutment of the bridge over the
Tuckahoe Creek,  46.94 m (154.0 ft) west of the SW corner of a stone block
garage located at 21908 Main Street, and 10.00 m (32.8 ft) north of power pole
"220", and  0.49 m (1.6 ft) above pavement level.  

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  6

                                                                                
Station ID: 8572669                         PUBLICATION DATE:  04/22/2013
Name:       HILLSBORO, TUCKAHOE CREEK                         
            MD
NOAA Chart: 12268                           Latitude:   38° 55.0' N (  38.91670)
USGS Quad:  RIDGELY                         Longitude:  75° 56.7' W ( -75.94500)


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


                         BENCH MARK STAMPING:  2669 D 2005
                         DESIGNATION:          857 2669 D

MONUMENTATION:           Tidal Station disk                    VM#:        17861
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Town Hall                             OPUS PID:        
LATITUDE:   38° 54.9' N (  38.91500)          LONGITUDE:  75° 56.7' W ( -75.94500)


The bench mark is located on the back side of the Hillsboro Town Hall, 20.30 m
(66.6 ft) NW of light pole "126," 12.31 m (40.4 ft) ESE of the west corner of
town hall, and 4.21 m (13.8 ft) WNW from the south corner of town hall.  

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  6

                                                                                
Station ID: 8572669                         PUBLICATION DATE:  04/22/2013
Name:       HILLSBORO, TUCKAHOE CREEK                         
            MD
NOAA Chart: 12268                           Latitude:   38° 55.0' N (  38.91670)
USGS Quad:  RIDGELY                         Longitude:  75° 56.7' W ( -75.94500)


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


                         BENCH MARK STAMPING:   
                         DESIGNATION:          47
                         ALIAS:                UNSTAMPED

MONUMENTATION:           Tidal Station disk                    VM#:        17863
AGENCY:                  Unknown                               IDB PID#:  HU0812
SETTING CLASSIFICATION:  Brick foundation                      OPUS PID:        
LATITUDE:   38° 55.0' N (  38.91670)          LONGITUDE:  75° 56.6' W ( -75.94330)


The bench mark is a disk set vertically in the NE corner of the original brick
foundation located east of the post office along State Highway ALT 404, at the
Frank Flemming House, and 1.2 m (3.9 ft) above the ground.  

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  6

                                                                                
Station ID: 8572669                         PUBLICATION DATE:  04/22/2013
Name:       HILLSBORO, TUCKAHOE CREEK                         
            MD
NOAA Chart: 12268                           Latitude:   38° 55.0' N (  38.91670)
USGS Quad:  RIDGELY                         Longitude:  75° 56.7' W ( -75.94500)


                            T I D A L   D A T U M S 


Tidal datums at HILLSBORO, TUCKAHOE CREEK based on:

     LENGTH OF SERIES:      4 MONTHS
     TIME PERIOD:           May 2005 - August 2005
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8571892 CAMBRIDGE, CHOPTANK RIVER


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

     MEAN HIGHER HIGH WATER                     MHHW   =  0.807
     MEAN HIGH WATER                            MHW    =  0.755
     MEAN SEA LEVEL                             MSL    =  0.447
     MEAN TIDE LEVEL                            MTL    =  0.406
     MEAN LOW WATER                             MLW    =  0.057
     MEAN LOWER LOW WATER                       MLLW   =  0.000

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     2669 A 2005                                 2.287    1.532
     2669 B 2005                                 3.074    2.319
     2669 C 2005                                 3.499    2.744
     2669 D 2005                                13.864   13.109
     47                                         14.344   13.589


Foot Notes:

Bench marks 2669 D 2005 and 47 are based on one differntial 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  6 of  6

                                                                                
Station ID: 8572669                         PUBLICATION DATE:  04/22/2013
Name:       HILLSBORO, TUCKAHOE CREEK                         
            MD
NOAA Chart: 12268                           Latitude:   38° 55.0' N (  38.91670)
USGS Quad:  RIDGELY                         Longitude:  75° 56.7' W ( -75.94500)


                             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.

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Products available at 8572669 Hillsboro, MD

Revised: 08/08/2018
NOAA / National Ocean Service
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