U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of 10

                                                                                
Station ID: 8638660                         PUBLICATION DATE:  05/02/2003
Name:       PORTSMOUTH,NORFOLK NAVAL SHIPYRD                  
            VA
NOAA Chart: 12221                           Latitude:   36° 49.3' N (  36.82170)
USGS Quad:  NORFOLK NORTH                   Longitude:  76° 17.6' W ( -76.29330)


To reach the bench marks from the intersection of Interstate Highway 264 and
Effingham Street (Route 141), proceed south 1.4 km (0.9 mi) to the Naval
Shipyard entrance.  At the pass office at the gate entrance, call 8273 for an
escort.  You must have an escort for the entrance to the CIA area.


                         T I D A L   B E N C H   M A R K S
                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of 10

                                                                                
Station ID: 8638660                         PUBLICATION DATE:  05/02/2003
Name:       PORTSMOUTH,NORFOLK NAVAL SHIPYRD                  
            VA
NOAA Chart: 12221                           Latitude:   36° 49.3' N (  36.82170)
USGS Quad:  NORFOLK NORTH                   Longitude:  76° 17.6' W ( -76.29330)


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


                 PRIMARY BENCH MARK STAMPING:   
                         DESIGNATION:          F 9 USN
                         ALIAS:                5-F9

MONUMENTATION:           Chiseled Square                       VM#:        10838
AGENCY:                  Department of Defense (DOD)           IDB PID#:  FX0171
SETTING CLASSIFICATION:  Dry Dock                              OPUS PID:        
LATITUDE:   36° 49.2' N (  36.82000)          LONGITUDE:  76° 17.6' W ( -76.29330)


The  primary bench mark is a chiseled square on the center of the rounded nose
of a granite coping at the SW corner of Dry Dock No. 1, 43 m (141 ft) east of
the south end of building No. 64, 4.66 m (15.3 ft) north of the north side of
the south granite wall of the dock, 3.4 m (11 ft) east of the west end of the
dock, and 1.8 m (6 ft) north of the north edge of the steps at the corner of the
dock.  Note: known as Navy Yard Basic Bench Mark (Historically designated as
5-F9 1913)

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of 10

                                                                                
Station ID: 8638660                         PUBLICATION DATE:  05/02/2003
Name:       PORTSMOUTH,NORFOLK NAVAL SHIPYRD                  
            VA
NOAA Chart: 12221                           Latitude:   36° 49.3' N (  36.82170)
USGS Quad:  NORFOLK NORTH                   Longitude:  76° 17.6' W ( -76.29330)


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


                         BENCH MARK STAMPING:  NO 1 1970
                         DESIGNATION:          TIDAL 1 STA 94

MONUMENTATION:           Tidal Station disk                    VM#:        10839
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  FX0173
SETTING CLASSIFICATION:  Concrete loading ramp                 OPUS PID:        
LATITUDE:   36° 49.3' N (  36.82170)          LONGITUDE:  76° 17.5' W ( -76.29170)


The bench mark is a disk set on top of the concrete along the south side of a
concrete loading ramp, 0.16 km (0.1 mi) east of building No. 73, 31.76 m (104.2
ft) west of the west side of the concrete seawall of the river, 15.2 m (50 ft)
west of the SW corner of the gage house building No. 227, 6.10 m (20.0 ft) south
of the south side of Wet Slip No. 2, and 0.21 m (0.7 ft) north of the south edge
of the concrete, and about level with the parking area.



                         BENCH MARK STAMPING:  NO 2 1973
                         DESIGNATION:          863 8660 TIDAL 2

MONUMENTATION:           Tidal Station disk                    VM#:        10840
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:  FX2219
SETTING CLASSIFICATION:  granite footing                       OPUS PID:        
LATITUDE:   36° 49.3' N (  36.82170)          LONGITUDE:  76° 17.5' W ( -76.29170)


The bench mark is a disk set in a granite footing at the east entrance to
building No. 62 (the Naval Ordanance System Support Office at the U.S. Naval
Shipyard in Portsmouth), 18 m (59 ft) north of the centerline of Chariolton
Street, 14.6 m (48 ft) south of the centerline of Hughes Street, 2.4 m (8 ft)
west of the west curb, and 0.30 m (1 ft) above sidewalk level.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of 10

                                                                                
Station ID: 8638660                         PUBLICATION DATE:  05/02/2003
Name:       PORTSMOUTH,NORFOLK NAVAL SHIPYRD                  
            VA
NOAA Chart: 12221                           Latitude:   36° 49.3' N (  36.82170)
USGS Quad:  NORFOLK NORTH                   Longitude:  76° 17.6' W ( -76.29330)


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


                         BENCH MARK STAMPING:  10 1938
                         DESIGNATION:          863 8660 TIDAL 10

MONUMENTATION:           Tidal Station disk                    VM#:        10841
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  FX0172
SETTING CLASSIFICATION:  Building                              OPUS PID:        
LATITUDE:   36° 49.3' N (  36.82170)          LONGITUDE:  76° 17.6' W ( -76.29330)


The bench mark is a disk set vertically into the east face of Sloat Hall
(Building No. 73) along the north side of Berrien Street, 11.43 m (37.5 ft)
north of the north curb of Berrien Street, 3.14 m (10.3 ft) west of the west
curb of Bell Avenue,  0.52 m (1.7 ft) north of the SE corner of Sloat Hall, and
1.16 m (3.8 ft) above ground.



                         BENCH MARK STAMPING:  11 1945
                         DESIGNATION:          863 8660 TIDAL 11

MONUMENTATION:           Tidal Station disk                    VM#:        10842
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  FX0162
SETTING CLASSIFICATION:  Concrete sidewalk                     OPUS PID:        
LATITUDE:   36° 48.7' N (  36.81170)          LONGITUDE:  76° 18.0' W ( -76.30000)


The bench mark is a disk set in the top of the concrete sidewalk at the NW
corner of Dry Dock No. 8, 36.42 m (119.5 ft) south of the SW corner of building
No. 269, 0.85 m (2.8 ft) south of the south rail of a track for a crane, and
0.46 m (1.5 ft) from the outside corner of the coping at the edge of the dock.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of 10

                                                                                
Station ID: 8638660                         PUBLICATION DATE:  05/02/2003
Name:       PORTSMOUTH,NORFOLK NAVAL SHIPYRD                  
            VA
NOAA Chart: 12221                           Latitude:   36° 49.3' N (  36.82170)
USGS Quad:  NORFOLK NORTH                   Longitude:  76° 17.6' W ( -76.29330)


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


                         BENCH MARK STAMPING:  863-8660 A 1975
                         DESIGNATION:          863 8660 A

MONUMENTATION:           Tidal Station disk                    VM#:        10843
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Concrete porch                        OPUS PID:        
LATITUDE:   36° 49.3' N (  36.82170)          LONGITUDE:  76° 17.6' W ( -76.29330)


The bench mark is a disk set in the top of a concrete porch on the south side of
building No. 22, 18.56 m (61.0 ft) north of the NE corner of building No. 300,
13.4 m (44 ft) east from the SW corner of building No. 22, and 0.40 m (1.3 ft)
above the sidewalk.



                         BENCH MARK STAMPING:  863-8660 B 1975
                         DESIGNATION:          863 8660 B

MONUMENTATION:           Tidal Station disk                    VM#:        10844
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Concrete coping                       OPUS PID:        
LATITUDE:   36° 49.3' N (  36.82170)          LONGITUDE:  76° 17.6' W ( -76.29330)


The bench mark is a disk set in the concrete coping of Dry Dock No. 4, 26.40 m
(86.6 ft) from the staff on the head of the NW stairway, and 0.52 m (1.7 ft)
west of the top step.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  6 of 10

                                                                                
Station ID: 8638660                         PUBLICATION DATE:  05/02/2003
Name:       PORTSMOUTH,NORFOLK NAVAL SHIPYRD                  
            VA
NOAA Chart: 12221                           Latitude:   36° 49.3' N (  36.82170)
USGS Quad:  NORFOLK NORTH                   Longitude:  76° 17.6' W ( -76.29330)


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


                         BENCH MARK STAMPING:  863-8660 C 1975
                         DESIGNATION:          863 8660 C

MONUMENTATION:           Tidal Station disk                    VM#:        10845
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Roof Support Foundation               OPUS PID:        
LATITUDE:   36° 49.3' N (  36.82170)          LONGITUDE:  76° 17.6' W ( -76.29330)


The bench mark is a disk set in the concrete base of the west metal column
supporting the roof of building No. 261, 32.25 m (105.8 ft) SE of the east
corner of building No. 163, 24.63 m (80.8 ft) NE of the north corner of building
No. 235, and 0.37 m (1.2 ft) NW of the west column.



                         BENCH MARK STAMPING:  863-8660 D 1975
                         DESIGNATION:          863 8660 D

MONUMENTATION:           Tidal Station disk                    VM#:        10846
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Concrete loading platform             OPUS PID:        
LATITUDE:   36° 49.3' N (  36.82170)          LONGITUDE:  76° 17.6' W ( -76.29330)


The bench mark is a disk set in the top of a concrete loading platform at the NW
end of building No. 275, 9.45 m (31 ft) from the west corner of building No.
275, and 5.76 m (18.9 ft) SW of the north corner of building No. 275.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  7 of 10

                                                                                
Station ID: 8638660                         PUBLICATION DATE:  05/02/2003
Name:       PORTSMOUTH,NORFOLK NAVAL SHIPYRD                  
            VA
NOAA Chart: 12221                           Latitude:   36° 49.3' N (  36.82170)
USGS Quad:  NORFOLK NORTH                   Longitude:  76° 17.6' W ( -76.29330)


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


                         BENCH MARK STAMPING:  863-8660 E 1975
                         DESIGNATION:          863 8660 E

MONUMENTATION:           Tidal Station disk                    VM#:        10847
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Concrete bulkhead                     OPUS PID:        
LATITUDE:   36° 49.3' N (  36.82170)          LONGITUDE:  76° 17.6' W ( -76.29330)


The bench mark is a disk set in the top center of the concrete bulkhead of wet
slip no. 4, 50.44 m (165.5 ft) west from the NE corner of wet slip No. 4, 6.43 m
(21.1 ft) south of the SW corner of building No. 830, and 4.88 m (16.0 ft) east
of the SW corner of a block-house for a concrete drain.



                         BENCH MARK STAMPING:  863-8660 F 1975
                         DESIGNATION:          863 8660 F

MONUMENTATION:           Tidal Station disk                    VM#:        10848
AGENCY:                  National Ocean Survey (NOS)           IDB PID#:        
SETTING CLASSIFICATION:  Concrete bulkhead                     OPUS PID:        
LATITUDE:   36° 49.3' N (  36.82170)          LONGITUDE:  76° 17.6' W ( -76.29330)


The bench mark is a disk set in the top of the concrete bulkhead next to the
second most southerly cleat of wet slip No. 5, 22.74 m (74.6 ft) north of the SW
corner of wet slip No. 5, 13.78 m (45.2 ft) east of the center of the road, and
0.34 m (1.1 ft) west of the seaward side of the bulkhead.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  8 of 10

                                                                                
Station ID: 8638660                         PUBLICATION DATE:  05/02/2003
Name:       PORTSMOUTH,NORFOLK NAVAL SHIPYRD                  
            VA
NOAA Chart: 12221                           Latitude:   36° 49.3' N (  36.82170)
USGS Quad:  NORFOLK NORTH                   Longitude:  76° 17.6' W ( -76.29330)


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


                         BENCH MARK STAMPING:  M 452 1971
                         DESIGNATION:          M 452

MONUMENTATION:           Bench Mark disk                       VM#:        10849
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  FX0170
SETTING CLASSIFICATION:  Concrete guardrail                    OPUS PID:        
LATITUDE:   36° 49.2' N (  36.82000)          LONGITUDE:  76° 17.7' W ( -76.29500)


The bench mark is a disk set on the top of a concrete guard rail on the west
side of the entrace to the most westerly steps on the north side of Dry Dock No.
3, 39 m (128 ft) NE of the center of the west end of the dry dock, 32.3 m (106
ft) south of the SW corner of building No. 300, and 0.91 m (3 ft) above blacktop
level.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  9 of 10

                                                                                
Station ID: 8638660                         PUBLICATION DATE:  05/02/2003
Name:       PORTSMOUTH,NORFOLK NAVAL SHIPYRD                  
            VA
NOAA Chart: 12221                           Latitude:   36° 49.3' N (  36.82170)
USGS Quad:  NORFOLK NORTH                   Longitude:  76° 17.6' W ( -76.29330)


                            T I D A L   D A T U M S 


Tidal datums at PORTSMOUTH,NORFOLK NAVAL SHIPYRD based on:

     LENGTH OF SERIES:      8 YEARS
     TIME PERIOD:           January 1979 - December 1986
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8638610 SEWELLS POINT, HAMPTON ROADS


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

     HIGHEST OBSERVED WATER LEVEL (09/18/1936)         =  2.449
     MEAN HIGHER HIGH WATER                     MHHW   =  0.946
     MEAN HIGH WATER                            MHW    =  0.882
     North American Vertical Datum              NAVD88 =  0.546
     MEAN SEA LEVEL                             MSL    =  0.464
     MEAN TIDE LEVEL                            MTL    =  0.462
     MEAN LOW WATER                             MLW    =  0.042
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (01/31/1966)         = -1.087

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     F 9 USN                                     2.044    1.162
     NO 1 1970                                   2.236    1.354
     NO 2 1973                                   2.625    1.743
     10 1938                                     3.829    2.947
     11 1945                                     2.935    2.053
     863-8660 A 1975                             3.024    2.142
     863-8660 B 1975                             2.436    1.554
     863-8660 C 1975                             2.969    2.087
     863-8660 D 1975                             3.661    2.779
     863-8660 E 1975                             2.489    1.607
     863-8660 F 1975                             2.986    2.104
     M 452 1971                                  3.049    2.167


                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page 10 of 10

                                                                                
Station ID: 8638660                         PUBLICATION DATE:  05/02/2003
Name:       PORTSMOUTH,NORFOLK NAVAL SHIPYRD                  
            VA
NOAA Chart: 12221                           Latitude:   36° 49.3' N (  36.82170)
USGS Quad:  NORFOLK NORTH                   Longitude:  76° 17.6' W ( -76.29330)


                             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.