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

                                                                                
Station ID: 8573364                         PUBLICATION DATE:  08/04/2011
Name:       TOLCHESTER BEACH, CHESAPEAKE BAY                  
            MD
NOAA Chart: 12278                           Latitude:   39° 12.8' N (  39.21333)
USGS Quad:  ROCK HALL                       Longitude:  76° 14.7' W ( -76.24500)


To reach the bench marks from the intersection of State Highways 213 and 291 in
Chestertown, proceed west on Route 291 for 0.8 km (0.5 mi) to Highway 20, turn
right and continue west on Highway 20 for 11.3 km (7.0 mi) to Highway 21. Turn
right and proceed west on Highway 21 for 5.3 km (3.3 mi) to the Tolchester
Marina. The bench marks are located between Route 21 and the entrance channel to
the marina. The tide gage is located on the north bulkhead along the entrance
channel.


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


                 PRIMARY BENCH MARK STAMPING:  3364 A 1983
                         DESIGNATION:          857 3364 A

MONUMENTATION:           Tidal Station disk                    VM#:         3159
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   39° 12.8' N (  39.21331)          LONGITUDE:  76° 14.7' W ( -76.24500)


The primary bench mark is a disk located on the SE side of a prominent hill
between the Marina and the Bay, 59.44 m (195.0 ft) SSW of the southernmost
corner of the tennis courts, 48.37 m (158.7 ft) SW of the NW corner of a wooden
bulkhead, 10.03 m (32.9 ft) WNW of the west edge of the wood bulkhead, and 0.76
m (2.5 ft) WNW of the west edge of the asphalt apron around the slip area. The
bench mark is set 0.12 m (0.4 ft) below ground, crimped to the top of a
stainless steel rod driven 17.1 m (56 ft) to refusal, and encased in a 4-inch
PVC pipe.

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

                                                                                
Station ID: 8573364                         PUBLICATION DATE:  08/04/2011
Name:       TOLCHESTER BEACH, CHESAPEAKE BAY                  
            MD
NOAA Chart: 12278                           Latitude:   39° 12.8' N (  39.21333)
USGS Quad:  ROCK HALL                       Longitude:  76° 14.7' W ( -76.24500)


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


                         BENCH MARK STAMPING:  KNOB 1950
                         DESIGNATION:          857 3364 KNOB

MONUMENTATION:           Triangulation Station disk            VM#:         3157
AGENCY:                  US Army Corps of Engineers (USE)      IDB PID#:        
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID:        
LATITUDE:   39° 12.8' N (  39.21331)          LONGITUDE:  76° 14.7' W ( -76.24500)


The bench mark is located on the top of a treed hill west of the boat basin and
on the south end of the hill, 19.9 m (65.3 ft) north of a gas pump, 14.9 m (48.9
ft) east-northeast of the northeast corner of the Shanty Beach bar, and 4.2 m
(13.8 ft) south from the center of a 0.6 m (2.0 ft) diameter oak tree.  The mark
is in a concrete post and sits 0.27 m (0.9 ft) above ground.



                         BENCH MARK STAMPING:  NO 6 1971
                         DESIGNATION:          857 3364 TIDAL 6

MONUMENTATION:           Tidal Station disk                    VM#:         3158
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID:        
LATITUDE:   39° 12.8' N (  39.21386)          LONGITUDE:  76° 14.6' W ( -76.24406)


The bench mark is a disk set in top of a concrete monument on the SW side of a
prominent hill in a small picnic area, 60.35 m (198.0 ft) north of the north
bulkhead along the entrance channel, 20.45 m (67.1 ft) NW of the center of 3
fuel tank vent pipes at the north edge of the parking lot, 12.10 m (39.7 ft)
north of a basketball goal post, 0.24 m (0.8 ft) south of an orange fiberglass
witness post, and 0.46 m (1.5 ft) below ground.

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

                                                                                
Station ID: 8573364                         PUBLICATION DATE:  08/04/2011
Name:       TOLCHESTER BEACH, CHESAPEAKE BAY                  
            MD
NOAA Chart: 12278                           Latitude:   39° 12.8' N (  39.21333)
USGS Quad:  ROCK HALL                       Longitude:  76° 14.7' W ( -76.24500)


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


                         BENCH MARK STAMPING:  3364 B 1983
                         DESIGNATION:          857 3364 B TIDAL

MONUMENTATION:           Tidal Station disk                    VM#:         3160
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID#: AJ8034
LATITUDE:   39° 12.9' N (  39.21475)          LONGITUDE:  76° 14.6' W ( -76.24339)


The bench mark is a disk located on the east side of the tennis courts, 31.85 m
(104.5 ft) north of the NW corner of a wooden bulkhead, 21.76 m (71.4 ft) SSW of
the easternmost wood fence post along the north edge of the Marina property,
18.59 m (61.0 ft) south of the SE corner of the fence around the tennis courts,
4.54 m (14.9 ft) SE of the fence along the tennis court and in line with the
nets, 0.91 m (3.0 ft) WNW of the WNW face of the tenth wood post from the road
on the WNW side of the asphalt apron.  The bench mark is set 0.12 m (0.4 ft)
below ground, crimped to the top of a stainless steel rod driven 18.3 m (60 ft)
to refusal, and encased in a 4-inch PVC pipe with a protective cap.

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

                                                                                
Station ID: 8573364                         PUBLICATION DATE:  08/04/2011
Name:       TOLCHESTER BEACH, CHESAPEAKE BAY                  
            MD
NOAA Chart: 12278                           Latitude:   39° 12.8' N (  39.21333)
USGS Quad:  ROCK HALL                       Longitude:  76° 14.7' W ( -76.24500)


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


                         BENCH MARK STAMPING:  3364 C 1983
                         DESIGNATION:          857 3364 C

MONUMENTATION:           Tidal Station disk                    VM#:         3161
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   39° 12.9' N (  39.21475)          LONGITUDE:  76° 14.5' W ( -76.24208)


The bench mark is a disk located on an earthen dam on the north side of Route 21
across from the entrance to the Tolchester Marina, 31.82 m (104.4 ft) SE of the
SE corner fence post for a hurricane fence by the pond on the north side of
Route 21, 24.60 m (80.7 ft) north of the eastern gate post at the entrance to
the marina, 22.19 m (72.8 ft) NNE of the western gate post, 13.35 m (43.8 ft) NE
of the centerline of Route 21, 5.76 m (18.9 ft) south of the waters edge of the
SE corner of the pond, and 0.09 m (0.30 ft) south of an orange fiberglass
witness post.  The bench mark is set 0.12 m (0.4 ft) below ground, crimped to
the top a stainless steel rod driven 16.4 m (54 ft) to refusal, and encased in a
4-inch PVC pipe with a protective cap.



                         BENCH MARK STAMPING:  3364 D 2003
                         DESIGNATION:          857 3364 D

MONUMENTATION:           Tidal Station disk                    VM#:        16991
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Foundation of boat storage            OPUS PID:        
LATITUDE:   39° 12.8' N (  39.21347)          LONGITUDE:  76° 14.5' W ( -76.24142)


The bench mark is a disk set in the foundation of a large corrugated steel
workshop/boat storage building on the east side of the Tolchester marina, 37.52
m (123.1 ft) east of the SE corner of the Tolchester marina office/restaurant,
15.33 m (50.3 ft) north of the south corner of the corrugated steel building,
15.31 m (50.2 ft) south of the north corner of the corrugated steel building,
and 0.27 m (0.9 ft) west of the west face of the corrugated steel building.

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

                                                                                
Station ID: 8573364                         PUBLICATION DATE:  08/04/2011
Name:       TOLCHESTER BEACH, CHESAPEAKE BAY                  
            MD
NOAA Chart: 12278                           Latitude:   39° 12.8' N (  39.21333)
USGS Quad:  ROCK HALL                       Longitude:  76° 14.7' W ( -76.24500)


                            T I D A L   D A T U M S 


Tidal datums at TOLCHESTER BEACH, CHESAPEAKE BAY based on:

     LENGTH OF SERIES:      16 YEARS
     TIME PERIOD:           Sept. 1994 - Aug. 2009 and Oct. 2009 - Sept. 2010
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8574680 BALTIMORE, FORT MCHENRY, PATAPSCO RIVER


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

     HIGHEST OBSERVED WATER LEVEL (09/19/2003)         =  2.412
     MEAN HIGHER HIGH WATER                     MHHW   =  0.527
     MEAN HIGH WATER                            MHW    =  0.432
     MEAN SEA LEVEL                             MSL    =  0.254
     MEAN TIDE LEVEL                            MTL    =  0.248
     MEAN LOW WATER                             MLW    =  0.064
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (04/01/1997)         = -0.958

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     3364 A 1983                                 1.923    1.491
     KNOB 1950                                   8.431    7.999
     NO 6 1971                                   2.057    1.625
     3364 B 1983                                 1.947    1.515
     3364 C 1983                                 3.246    2.814
     3364 D 2003                                 2.628    2.196


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

                                                                                
Station ID: 8573364                         PUBLICATION DATE:  08/04/2011
Name:       TOLCHESTER BEACH, CHESAPEAKE BAY                  
            MD
NOAA Chart: 12278                           Latitude:   39° 12.8' N (  39.21333)
USGS Quad:  ROCK HALL                       Longitude:  76° 14.7' W ( -76.24500)


                             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.