U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  5

                                                                                
Station ID: 8772447                         PUBLICATION DATE:  06/10/2011
Name:       USCG FREEPORT, FREEPORT ENTR CHANNEL              
            TX
NOAA Chart: 11330                           Latitude:   28° 56.6' N (  28.94331)
USGS Quad:  FREEPORT                        Longitude:  95° 18.1' W ( -95.30250)


To reach the tide station from the intersection of FM 523 and state highway 322
NNE of the cith of Freeport, proceed SE on 332 3.7 mi (6.0 km) over the
intercoastal bridge to the intersection of 332 and CR 257.  Turn right SW on CR
257 (Fort Velasco Drive) into the residential neighborhood D, for 0.85 mi (1.37
km ) to Thunder Road.  Turn right NW on Thunder Road 0.40 mi (0.64 km ) bearing
left to the entrance of the USCG Freeport Station on the left.


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


                 PRIMARY BENCH MARK STAMPING:  2447 A 2006
                         DESIGNATION:          877 2447 A TIDAL
                         ALIAS:                2447 A PBM

MONUMENTATION:           Flange-encased Rod                    VM#:        18442
AGENCY:                  Conrad Blucher Institute (CBI)        IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   28° 56.6' N (  28.94333)          LONGITUDE:  95° 18.1' W ( -95.30250)


The primary bench mark is a flange-encased rod located on the USCG Freeport
property, 9.6 m (31.5 ft) east along the driveway leading to the finger pier on
the southernmost side of the station, 1.67 m (5.479 ft) north of the fence on
the southernmost side of the station, and 0.72 m (2.4 ft) south of the
southernmost concrete driveway leading to the finger pier of the southernmost
side of the station adjacent to the Freeport Entrance Channel.  The bench mark
is set 0.100 m (0.328 ft) below grade, driven 13.4 m (44.0 ft) to refusal, and
is encased in a 0.60 m (1.97 ft) PVC pipe and concrete kickblock.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  5

                                                                                
Station ID: 8772447                         PUBLICATION DATE:  06/10/2011
Name:       USCG FREEPORT, FREEPORT ENTR CHANNEL              
            TX
NOAA Chart: 11330                           Latitude:   28° 56.6' N (  28.94331)
USGS Quad:  FREEPORT                        Longitude:  95° 18.1' W ( -95.30250)


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


                         BENCH MARK STAMPING:  2447 B 2006
                         DESIGNATION:          877 2447 B TIDAL
                         ALIAS:                2447 B

MONUMENTATION:           Tidal Station disk                    VM#:        18443
AGENCY:                  Conrad Blucher Institute (CBI)        IDB PID#:        
SETTING CLASSIFICATION:  Retaining wall                        OPUS PID:        
LATITUDE:   28° 56.6' N (  28.94367)          LONGITUDE:  95° 18.2' W ( -95.30278)


The bench mark is a disk set on top of the NW most point of the north retaining
wall of the boat ramp , 17.20 m (56.4 ft) ENE of a concrete fuel tank, 0.42 m
(1.38 ft) east of the NW end of the retaining wall.



                         BENCH MARK STAMPING:  2447 C 2006
                         DESIGNATION:          877 2447 C TIDAL
                         ALIAS:                2447 C

MONUMENTATION:           Flange-encased Rod                    VM#:        18444
AGENCY:                  Conrad Blucher Institute (CBI)        IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID:        
LATITUDE:   28° 56.7' N (  28.94417)          LONGITUDE:  95° 18.2' W ( -95.30311)


The bench mark is a flange-encased rod located inside the north fence of the
USSCG Freeport property, 27 m (88.6 ft) NNE of a light pole, 24.2 m (79.4 ft) NW
of the PLCO well water tank No. 10691, and 0.9 m (2.95 ft) east of the fence
line.  The bench mark is driven 11 m (36.1 ft) and encased in a 6 inch PVC pipe
and concrete kickblock.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  5

                                                                                
Station ID: 8772447                         PUBLICATION DATE:  06/10/2011
Name:       USCG FREEPORT, FREEPORT ENTR CHANNEL              
            TX
NOAA Chart: 11330                           Latitude:   28° 56.6' N (  28.94331)
USGS Quad:  FREEPORT                        Longitude:  95° 18.1' W ( -95.30250)


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


                         BENCH MARK STAMPING:  USCG 1997
                         DESIGNATION:          USCG
                         ALIAS:                USCG

MONUMENTATION:           Bench Mark disk                       VM#:        18445
AGENCY:                  US Coast and Geodetic Survey
                         (USC&GS)                              IDB PID#:        
SETTING CLASSIFICATION:  Concrete monument                     OPUS PID:        
LATITUDE:   28° 56.7' N (  28.94444)          LONGITUDE:  95° 18.2' W ( -95.30278)


The bench mark is a disk set on top of 0.3 m x 0.3 m (1.0 ft x 1.0 ft) concrete
monument, 31 m (101.7 ft) NE of the AC cooling unit at the NE corner of the
maintenance building, 30.6 m (100.4 ft) south of the north fence line, and 4.35
m (14.27 ft) NE of a radio supression antenna located NE of the maintenance
building, and  0.7 m (2.3 ft) above ground level.



                         BENCH MARK STAMPING:  2447 E 2006
                         DESIGNATION:          877 2447 E TIDAL
                         ALIAS:                2447 E

MONUMENTATION:           Flange-encased Rod                    VM#:        18446
AGENCY:                  Conrad Blucher Institute (CBI)        IDB PID#:        
SETTING CLASSIFICATION:  Stainless steel rod                   OPUS PID#: DP0699
LATITUDE:   28° 56.7' N (  28.94472)          LONGITUDE:  95° 18.2' W ( -95.30306)


The bench mark is flange-encased rod, 322 NNE of the cith of Freeport, proceed
SE on 332 3.7 mi (6.0 km) over the intercoastal bridge to the intersection of
332 and CR 257.  Turn right SW on CR 257 (Fort Velasco Drive) into the
residential neighborhood D, for 0.85 mi (1.37 km ) to Thunder Road.  Turn right
NW on Thunder Road 0.40 mi (0.64 km ) bearing left to the entrance of the USCG
Freeport Station on the left.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  4 of  5

                                                                                
Station ID: 8772447                         PUBLICATION DATE:  06/10/2011
Name:       USCG FREEPORT, FREEPORT ENTR CHANNEL              
            TX
NOAA Chart: 11330                           Latitude:   28° 56.6' N (  28.94331)
USGS Quad:  FREEPORT                        Longitude:  95° 18.1' W ( -95.30250)


                            T I D A L   D A T U M S 


Tidal datums at USCG FREEPORT, FREEPORT ENTR CHANNEL based on:

     LENGTH OF SERIES:      4 YEARS
     TIME PERIOD:           December 2006 - November 2010
     TIDAL EPOCH:           1983-2001
     CONTROL TIDE STATION:  8771510 GALVESTON PLEASURE PIER, GULF OF MEXICO


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

     HIGHEST OBSERVED WATER LEVEL (09/12/2008)         =  2.250
     MEAN HIGHER HIGH WATER                     MHHW   =  0.549
     MEAN HIGH WATER                            MHW    =  0.502
     MEAN SEA LEVEL                             MSL    =  0.296
     MEAN TIDE LEVEL                            MTL    =  0.291
     MEAN LOW WATER                             MLW    =  0.079
     MEAN LOWER LOW WATER                       MLLW   =  0.000
     LOWEST  OBSERVED WATER LEVEL (03/22/2010)         = -0.827

North American Vertical Datum (NAVD88)

Bench Mark Elevation Information                In METERS above:

     Stamping or Designation                    MLLW        MHW

     2447 A 2006                                 1.573    1.071
     2447 B 2006                                 2.157    1.655
     2447 C 2006                                 1.548    1.046
     USCG 1997                                   2.753    2.251
     2447 E 2006                                 1.800    1.298


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

                                                                                
Station ID: 8772447                         PUBLICATION DATE:  06/10/2011
Name:       USCG FREEPORT, FREEPORT ENTR CHANNEL              
            TX
NOAA Chart: 11330                           Latitude:   28° 56.6' N (  28.94331)
USGS Quad:  FREEPORT                        Longitude:  95° 18.1' W ( -95.30250)


                             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.