U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
Datums Page                                                        Page  1 of  4

                                                   PUBLICATION DATE:  07/11/1984
Station ID: 8540433                                SUPERCEDED DATE:   04/21/2003
Name:       MARCUS HOOK, DELAWARE RIVER                       
            PENNSYLVANIA
NOAA Chart: 12312                                  Latitude:         39° 48.7' N
USGS Quad:  MARCUS HOOK                            Longitude:        75° 24.7' W


To reach the tidal bench marks from the intersection of U.S. Route 13 bypass
(Ridge Avenue) and Market Street in the town of Marcus Hook, Pennsylvania,
proceed 1.0 mile (1.6 km) SE on Market Street to the waterfront of the Delaware
River, where the U.S. Army Defense Logistics Agency ECS #27 (GM), Marcus Hook is
located.  The bench marks are located in the area around the U.S. Army Defense
Logistics Agency.  The tide staff and gage were located at the end of the
longest wooden pier.


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


                 PRIMARY BENCH MARK STAMPING:  0433 E 1981

MONUMENTATION:           Survey Disk                               VM#:     2904
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Foundation


The bench mark is set flush on the eastern edge of the flagpole foundation, 110
feet (34 m) NNW of Bench Mark 0433 D 1981, 39 feet (12 m) from the northernmost
corner of the U.S. Army (DLA) building and 2 feet (0.6 m) west of the outer edge
of the foundation.



                         BENCH MARK STAMPING:  0433 A 1981

MONUMENTATION:           Survey Disk                               VM#:     2900
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Ice Breaker


The bench mark is set flush on the NE corner of the most offshore ice breaker,
300 feet (91 m) offshore, 123 feet (37 m) NW of the tide gage location and 65
feet (20 m) SW of the wooden pier.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  2 of  4

                                                   PUBLICATION DATE:  07/11/1984
Station ID: 8540433                                SUPERCEDED DATE:   04/21/2003
Name:       MARCUS HOOK, DELAWARE RIVER                       
            PENNSYLVANIA
NOAA Chart: 12312                                  Latitude:         39° 48.7' N
USGS Quad:  MARCUS HOOK                            Longitude:        75° 24.7' W


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


                         BENCH MARK STAMPING:  0433 B 1981

MONUMENTATION:           Survey Disk                               VM#:     2901
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Ice Breaker


The bench mark is set flush on the SE corner of the inshore ice breaker, 175
feet (53 m) offshore, 122 feet (37 m) NW of Bench Mark 0433 A 1981, and 65 feet
(20 m) west of the wooden pier.



                         BENCH MARK STAMPING:  0433 C 1981

MONUMENTATION:           Survey Disk                               VM#:     2902
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Entrance


The bench mark is set flush in the entrance to the U.S. Army Defense Logistics
Agency wooden pier, 175 feet (53 m) north of Bench Mark 0433 B 1981, 36 feet (11
m) east of the east corner of a hexagon-shaped building, and 1 foot (0.3 m) from
the anchor fence.



                         BENCH MARK STAMPING:  0433 D 1981

MONUMENTATION:           Survey Disk                               VM#:     2903
AGENCY:                                                            PID:         
SETTING CLASSIFICATION:  Concrete Sidewalk


The bench mark is set flush in the sidewalk of the U.S. Army Defense Logistics
Agency ECS #27 (GM), 72 feet (22 m) NW from Bench Mark 0433 C 1981, 20 feet (6
m) north of the north corner of a hexagon-shaped building, 13 feet (4 m) SE of
the SE corner of the U.S. Army (DLA) building, and 1 foot (0.3 m) north of a
lamp pole.

                          U.S. DEPARTMENT OF COMMERCE
                National Oceanic and Atmospheric Administration
                            National Ocean Service
                                                                   Page  3 of  4

                                                   PUBLICATION DATE:  07/11/1984
Station ID: 8540433                                SUPERCEDED DATE:   04/21/2003
Name:       MARCUS HOOK, DELAWARE RIVER                       
            PENNSYLVANIA
NOAA Chart: 12312                                  Latitude:         39° 48.7' N
USGS Quad:  MARCUS HOOK                            Longitude:        75° 24.7' W


                            T I D A L   D A T U M S 


Tidal datums at MARCUS HOOK, DELAWARE RIVER based on:

     LENGTH OF SERIES:      5 MONTHS
     TIME PERIOD:           JUNE-OCTOBER 1982
     TIDAL EPOCH:           1960-1978
     CONTROL TIDE STATION:  8545530 PHILADELPHIA


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

     HIGHEST OBSERVED WATER LEVEL (10/10/1982)    =   7.68
     MEAN HIGHER HIGH WATER (MHHW)                =   6.12
     MEAN HIGH WATER (MHW)                        =   5.72
     MEAN TIDE LEVEL (MTL)                        =   2.96
     MEAN LOW WATER (MLW)                         =   0.19
     MEAN LOWER LOW WATER (MLLW)                  =   0.00
     LOWEST  OBSERVED WATER LEVEL (09/24/1981)    =  -1.42

National Geodetic Vertical Datum (NGVD 29)

Bench Mark Elevation Information           In FEET above:

     Stamping or Designation               MLLW        MHW

     0433 E 1981                           11.30      5.58
     0433 A 1981                            8.37      2.65
     0433 B 1981                            8.93      3.21
     0433 C 1981                           10.07      4.35
     0433 D 1981                           10.39      4.67


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

                                                   PUBLICATION DATE:  07/11/1984
Station ID: 8540433                                SUPERCEDED DATE:   04/21/2003
Name:       MARCUS HOOK, DELAWARE RIVER                       
            PENNSYLVANIA
NOAA Chart: 12312                                  Latitude:         39° 48.7' N
USGS Quad:  MARCUS HOOK                            Longitude:        75° 24.7' W


                             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 (NAVD 88).

NGVD 29 is a fixed datum adopted as a national standard geodetic reference for
heights but is now considered superseded.  NGVD 29 is sometimes referred to as
Sea Level Datum of 1929 or as Mean Sea Level on some early issues of Geological
Survey Topographic Quads.  NGVD 29 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 NGVD 29 are available from the National
Geodetic Survey (NGS) data base via the World Wide Web at 
National Geodetic Survey.

NAVD 88 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.  NAVD 88 replaces NGVD 29 as the national
standard geodetic reference for heights.  Bench mark elevations relative to
NAVD 88 are available from NGS through the World Wide Web at 
National Geodetic Survey.

NGVD 29 and NAVD 88 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 NAVD 88 elevation is shown on the Elevations of Tidal Datums Table Referred
to MLLW only when two or more of the bench marks listed have NAVD 88 elevations.
The NAVD 88 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, NAVD 88 bench mark elevations computed indirectly from the tidal
datums elevation table may differ slightly from NAVD 88 elevations listed for
each bench mark in the NGS database.