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

                                                                                
Station ID: 8573349                         PUBLICATION DATE:  10/12/2011
Name:       CRUMPTON, CHESTER RIVER                           
            MD
NOAA Chart: 12272                           Latitude:   39° 14.7' N (  39.24500)
USGS Quad:  CHURCH HILL                     Longitude:  75° 55.5' W ( -75.92500)


To reach the tidal bench marks from the intersection of MD-213 and MD-544 in
Chestertown, MD, proceed east on MD-544 (McGinnes Road) towards Crumpton for 7.6
km (4.7 mi), turn left on Deep Landing Road, then continue north for 2.6 km (1.6
mi) to the County Park on the Chester River.  The bench marks are up the hill
along Deep Landing Road and the tide gauge was on the sea wall of the park.


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


                 PRIMARY BENCH MARK STAMPING:  3349 A 2005
                         DESIGNATION:          857 3349 A

MONUMENTATION:           Flange-encased Rod                    VM#:        17852
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod in sleeve         OPUS PID:        
LATITUDE:   39° 14.6' N (  39.24330)          LONGITUDE:  75° 57.6' W ( -75.96000)


The primary bench mark is a flange-encased rod located on the corner of Deep
Landing Road and Hoffman Lane, 11.13 m (36.5 ft) SE of the centerline of the
gravel drive of residence 907, 6.95 m (22.8 ft) south of Hoffman Lane, and 6.31
m (20.7 ft) ESE of center line of Deep Landing Road.  The datum point is flush
with the ground, being the top of a stainless steel rod driven 22.7 m (74 ft) to
refusal, in a sleeve extending to a depth of 0.6 m (2.0 ft) and encased in 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: 8573349                         PUBLICATION DATE:  10/12/2011
Name:       CRUMPTON, CHESTER RIVER                           
            MD
NOAA Chart: 12272                           Latitude:   39° 14.7' N (  39.24500)
USGS Quad:  CHURCH HILL                     Longitude:  75° 55.5' W ( -75.92500)


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


                         BENCH MARK STAMPING:  3349 C 2005
                         DESIGNATION:          857 3349 C

MONUMENTATION:           Flange-encased Rod                    VM#:        17853
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod in sleeve         OPUS PID:        
LATITUDE:   39° 14.6' N (  39.24330)          LONGITUDE:  75° 57.7' W ( -75.96170)


The bench mark is a flange-encased rod located along Deep Landing Road, 15.67 m
(51.4 ft) south of a gravel drive at residence 801 Deep Landing Road, 6.25 m
(20.5 ft) east of the centerline of Deep Landing Road, 3.75 m (12.3 ft) west of
power pole "193 97 22" and 0.46 m (1.5 ft) west of a witness post.  The datum
point is flush with the ground, being the top of a stainless steel rod driven
14.6 m (48 ft) to refusal, in a sleeve extending to a depth of 0.6 m (2.0 ft)
and encased in a 5-inch NOS logo cap.



                         BENCH MARK STAMPING:  3349 B 2005
                         DESIGNATION:          857 3349 B

MONUMENTATION:           Flange-encased Rod                    VM#:        17854
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod in sleeve         OPUS PID:        
LATITUDE:   39° 14.6' N (  39.24330)          LONGITUDE:  75° 57.7' W ( -75.96170)


The bench mark is a flange-encased rod located along Deep Landing Road, 23.90
meters (78.4 ft) west of the SW corner of a white house (residence 113 Deep
Landing Road), 11.80 m (38.7 ft) north of the residence driveway at 107 Deep
Landing Road, 4.82 m (15.8 ft) NW of the centerline of Deep Landing Road, and
0.43 m (1.4 ft) ESE of a witness post.  The datum point is flush with the
ground, being the top of a stainless steel rod driven 15.8 m (52 ft) to refusal,
in a sleeve extending to a depth of 0.6 m (2.0 ft) and encased in a 5-inch NOS
logo cap.      

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

                                                                                
Station ID: 8573349                         PUBLICATION DATE:  10/12/2011
Name:       CRUMPTON, CHESTER RIVER                           
            MD
NOAA Chart: 12272                           Latitude:   39° 14.7' N (  39.24500)
USGS Quad:  CHURCH HILL                     Longitude:  75° 55.5' W ( -75.92500)


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


                         BENCH MARK STAMPING:  3349 D 2005
                         DESIGNATION:          857 3349 D

MONUMENTATION:           Tidal Station disk                    VM#:        17855
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Flange-encased rod                    OPUS PID:        
LATITUDE:   39° 14.4' N (  39.24025)          LONGITUDE:  75° 57.5' W ( -75.95894)


The bench mark is a stainless steel rod on the SE corner of the parking lot of
the boat ramp at the end of the deep landing road,18.2 m (59.7 ft) south of the
tide station, 14.5 m (47.6 ft) SSE of the SE corner of the bulkhead of the
public boat ramp, 9.0 m (29.5 ft) SSW of a fire hydrant on the east side of the
boat ramp parking lot at the end of the deep landing road, 7.3 m (24.0 ft) SW of
the SW corner of a house at 101 Hoffman Ln, and 0.3 m (1.0 ft) W of a witness
post. The bench mark is set flush in the ground, driven 23.7 m (77.8 ft) to
refusal, with a sleeve extending to a depth of 1.8 m (5.9 ft) and encased in a
5-inch PVC pipe, with a 5-inch NOS logo cap.  The PVC pipe is surrounded by a
concrete kick block.  

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

                                                                                
Station ID: 8573349                         PUBLICATION DATE:  10/12/2011
Name:       CRUMPTON, CHESTER RIVER                           
            MD
NOAA Chart: 12272                           Latitude:   39° 14.7' N (  39.24500)
USGS Quad:  CHURCH HILL                     Longitude:  75° 55.5' W ( -75.92500)


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


                         BENCH MARK STAMPING:  3349 E 2005
                         DESIGNATION:          857 3349 E

MONUMENTATION:           Tidal Station disk                    VM#:        17856
AGENCY:                  National Ocean Service (NOS)          IDB PID#:        
SETTING CLASSIFICATION:  Flange-encased rod                    OPUS PID:        
LATITUDE:   39° 14.3' N (  39.23825)          LONGITUDE:  75° 57.6' W ( -75.96000)


The bench mark is a stainless steel rod set in the vicinity of the boat ramp at
the end of the deep landing road, 18.7 m (61.4 ft) south of the south side of
the house at 801 Deep Landing Rd, 9.5 m (31.2 ft) SE of a utility pole numbered
193.97.21 on the corner of Deep Landing Rd and Hickory Ln, 9.2 m (30.2 ft) east
of the eastside of a house at 733 Deep Landing Rd,6.4 m SW of the center of
intersection of Pine Grove Lane and Deep Landing Rd, 1.4 m (4.59 ft) west of the
centerline of Deep Landing Rd, 0.7 m (2.3 ft) east of a turkey oak tree at 733
Deep Landing Rd, and 0.2 m (0.7 ft) east of a carbonate witness post. The bench
mark is set flush with the ground, driven 23.7 meters (77.8 ft) to refusal, with
a sleeve extending to a depth of 1.8 m (5.9 ft) and encased in a 5-inch PVC pipe
with a 5-inch NOS logo cap.  The PVC is surrounded by a cement kick block.

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

                                                                                
Station ID: 8573349                         PUBLICATION DATE:  10/12/2011
Name:       CRUMPTON, CHESTER RIVER                           
            MD
NOAA Chart: 12272                           Latitude:   39° 14.7' N (  39.24500)
USGS Quad:  CHURCH HILL                     Longitude:  75° 55.5' W ( -75.92500)


                            T I D A L   D A T U M S 


Tidal datums at CRUMPTON, CHESTER RIVER based on:

     LENGTH OF SERIES:      3 YEARS
     TIME PERIOD:           May 2005 - April 2008
     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 (10/01/2010)         =  1.586
     MEAN HIGHER HIGH WATER                     MHHW   =  0.841
     MEAN HIGH WATER                            MHW    =  0.748
     MEAN SEA LEVEL                             MSL    =  0.419
     MEAN TIDE LEVEL                            MTL    =  0.411
     MEAN LOW WATER                             MLW    =  0.074
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (01/15/2006)         = -0.704

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     3349 A 2005                                 6.689    5.941
     3349 C 2005                                 9.097    8.349
     3349 B 2005                                 8.015    7.267
     3349 D 2005                                 3.490    2.742
     3349 E 2005                                 9.729    8.981


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

                                                                                
Station ID: 8573349                         PUBLICATION DATE:  10/12/2011
Name:       CRUMPTON, CHESTER RIVER                           
            MD
NOAA Chart: 12272                           Latitude:   39° 14.7' N (  39.24500)
USGS Quad:  CHURCH HILL                     Longitude:  75° 55.5' W ( -75.92500)


                             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.