U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  7

                                                                                
Station ID: 9415143                         PUBLICATION DATE:  11/23/2010
Name:       CROCKETT, CARQUINEZ STRAIT                        
            CA
NOAA Chart: 18654                           Latitude:   38°  3.5' N (  38.05830)
USGS Quad:  BENICA                          Longitude: 122° 13.4' W (-122.22300)


To reach the tidal bench marks from Oakland, proceed north on U.S. Highway 80
for 35 km (22 mi) to the City of Crockett, then exit at Crockett Boulevard
(Pomona Street) and proceed east for 0.7 km (0.4 mi) to Rolph Avenue, then turn
left onto Rolph Avenue and proceed north for 0.5 km (0.3 mi) to the main gate at
the California and Hawaiian Sugar Company Plant.  The bench marks are located
along the railroad tracks and near the sugar plant.  The tide gage and staff
were located on a piling on the west side of the dock for the sugar plant.


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


                 PRIMARY BENCH MARK STAMPING:  2 1929
                         DESIGNATION:          941 5143 TIDAL 2

MONUMENTATION:           Tidal Station disk                    VM#:         8575
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  JT0527
SETTING CLASSIFICATION:  Brick wall of building                OPUS PID:        
LATITUDE:   38°  3.4' N (  38.05670)          LONGITUDE: 122° 13.2' W (-122.22000)


The primary bench mark is a disk set vertically in the south face of a brick
wall of the shop building, near the main gate of the sugar plant, 30 m (100 ft)
west of the SW corner of the building, 18 m (60 ft) NE of the lower gate at the
entrance to the refinery, 15 m (50 ft) north of the entrance to California and
Hawaiian Sugar refinery, 1 m (5 ft) east of the east end of the south entrance,
and 0.46 m (1.5 ft) above the ground.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  7

                                                                                
Station ID: 9415143                         PUBLICATION DATE:  11/23/2010
Name:       CROCKETT, CARQUINEZ STRAIT                        
            CA
NOAA Chart: 18654                           Latitude:   38°  3.5' N (  38.05830)
USGS Quad:  BENICA                          Longitude: 122° 13.4' W (-122.22300)


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


                         BENCH MARK STAMPING:  TIDAL 7 1967
                         DESIGNATION:          941 5143 TIDAL 7

MONUMENTATION:           Bench Mark disk                       VM#:         8576
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  JT0529
SETTING CLASSIFICATION:  Brick wall of building                OPUS PID:        
LATITUDE:   38°  3.4' N (  38.05670)          LONGITUDE: 122° 13.2' W (-122.22000)


The bench mark is a disk set vertically in the south brick wall of Char House
No. 3 filtration house at the California and Hawaiian Sugar refinery, 91 m (300
ft) NE of the lower gate to the refinery, 2.13 m (7.0 ft) east of the center
door No. 6, 2.04 m (6.7 ft) west of the SE corner of the building, and 0.79 m
(2.6 ft) above the concrete sidewalk.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  7

                                                                                
Station ID: 9415143                         PUBLICATION DATE:  11/23/2010
Name:       CROCKETT, CARQUINEZ STRAIT                        
            CA
NOAA Chart: 18654                           Latitude:   38°  3.5' N (  38.05830)
USGS Quad:  BENICA                          Longitude: 122° 13.4' W (-122.22300)


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


                         BENCH MARK STAMPING:  M 1198 1969
                         DESIGNATION:          M 1198

MONUMENTATION:           Bench Mark disk                       VM#:         8577
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  JT0533
SETTING CLASSIFICATION:  Concrete pier                         OPUS PID:        
LATITUDE:   38°  3.3' N (  38.05500)          LONGITUDE: 122° 13.5' W (-122.22500)


The bench mark is a disk set vertically in the north face of the first concrete
pier south of the east lanes of the Interstate Highway 80 overpass, 0.5 km (0.3
mi) west along the Southern Pacific Railroad tracks from the refinery dock,
49.56 m (162.6 ft) SW of and across the track from bench mark H.L. MON 33, 17.53
m (57.5 ft) south of the rail of the south track, and 0.55 m (1.8 ft) west of
the NE end of the concrete pier.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  7

                                                                                
Station ID: 9415143                         PUBLICATION DATE:  11/23/2010
Name:       CROCKETT, CARQUINEZ STRAIT                        
            CA
NOAA Chart: 18654                           Latitude:   38°  3.5' N (  38.05830)
USGS Quad:  BENICA                          Longitude: 122° 13.4' W (-122.22300)


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


                         BENCH MARK STAMPING:  SECTION 6 T2NR3W
                         DESIGNATION:          SECTION 6 T2NR3W

MONUMENTATION:           Survey disk                           VM#:         8578
AGENCY:                  Contra Costa County                   IDB PID#:        
SETTING CLASSIFICATION:  Concrete block                        OPUS PID:        
LATITUDE:   38°  3.5' N (  38.05830)          LONGITUDE: 122° 13.4' W (-122.22300)


The bench mark is a disk set in a concrete block cube at the corner indicated by
the stamping, beneath Interstate Highway 80 northbound lanes of the bridge over
Carquinez Strait, and 110 m (361 ft) SW of bench mark M 1198 1969.



                         BENCH MARK STAMPING:  H.L. MON 33
                         DESIGNATION:          941 5143 H.L. MON 33

MONUMENTATION:           Survey disk                           VM#:         8579
AGENCY:                  US Army Corps of Engineers (USE)      IDB PID#:        
SETTING CLASSIFICATION:  Concrete post                         OPUS PID:        
LATITUDE:   38°  3.5' N (  38.05830)          LONGITUDE: 122° 13.4' W (-122.22300)


The bench mark is a disk set in top of a round concrete post along the shore
north of the railroad tracks, west of the west end of the California and
Hawaiian Sugar Refinery Company wharf, and 0.61 m (2.0 ft) above the ground.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  5 of  7

                                                                                
Station ID: 9415143                         PUBLICATION DATE:  11/23/2010
Name:       CROCKETT, CARQUINEZ STRAIT                        
            CA
NOAA Chart: 18654                           Latitude:   38°  3.5' N (  38.05830)
USGS Quad:  BENICA                          Longitude: 122° 13.4' W (-122.22300)


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


                         BENCH MARK STAMPING:   
                         DESIGNATION:          TIDAL 3
                         ALIAS:                3

MONUMENTATION:           Nail                                  VM#:         8580
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:  JT0526
SETTING CLASSIFICATION:  Concrete post                         OPUS PID:        
LATITUDE:   38°  3.4' N (  38.05670)          LONGITUDE: 122° 13.2' W (-122.22000)


The bench mark is a nail head set in top of a concrete post along the outside of
south wall and near the main gate of the California and Hawaiian Sugar Refinery,
16 m (51 ft) east of the gate in the wall, 2 m (7 ft) north of the Southern
Pacific Railroad Company side track, 1 m (3 ft) west of the fourth post east of
the gate, and 0.06 m (0.2 ft) above the ground.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  6 of  7

                                                                                
Station ID: 9415143                         PUBLICATION DATE:  11/23/2010
Name:       CROCKETT, CARQUINEZ STRAIT                        
            CA
NOAA Chart: 18654                           Latitude:   38°  3.5' N (  38.05830)
USGS Quad:  BENICA                          Longitude: 122° 13.4' W (-122.22300)


                            T I D A L   D A T U M S 


Tidal datums at CROCKETT, CARQUINEZ STRAIT based on:

     LENGTH OF SERIES:      1 YEAR
     TIME PERIOD:           July 1977 - June 1978
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  9415144 PORT CHICAGO, SUISUN BAY


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

     MEAN HIGHER HIGH WATER                     MHHW   =  1.812
     MEAN HIGH WATER                            MHW    =  1.643
     MEAN SEA LEVEL                             MSL    =  0.980
     MEAN TIDE LEVEL                            MTL    =  0.973
     MEAN LOW WATER                             MLW    =  0.303
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     North American Vertical Datum              NAVD88 = -0.118

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     2 1929                                      3.936    2.293
     TIDAL 7 1967                                4.238    2.595
     M 1198 1969                                 4.046    2.403
     SECTION 6 T2NR3W                            4.204    2.561
     H.L. MON 33                                 3.769    2.126
     TIDAL 3                                     3.935    2.292


Foot Notes:

Bench mark SECTION 6 T2NR3W is based on one differential leveling connection and
does not meet the quality control standards of the NOS.  Therefore, caution
should be used when deriving elevations for this mark. 

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

                                                                                
Station ID: 9415143                         PUBLICATION DATE:  11/23/2010
Name:       CROCKETT, CARQUINEZ STRAIT                        
            CA
NOAA Chart: 18654                           Latitude:   38°  3.5' N (  38.05830)
USGS Quad:  BENICA                          Longitude: 122° 13.4' W (-122.22300)


                             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.