U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Datums Page Page 1 of 5
PUBLICATION DATE: 12/26/1985
Station ID: 8577385 SUPERCEDED DATE: 04/21/2003
Name: NAVY SEAPLANE BASIN, CHESAPEAKE BAY
MARYLAND
NOAA Chart: 12264 Latitude: 38° 16.3' N
USGS Quad: SOLOMONS ISLAND Longitude: 76° 23.8' W
To reach the tidal bench marks from Lexington Park, Maryland, on Maryland Route
235 south, proceed to the intersection of Maryland Route 246 and Maryland Route
235, turn left onto Cedar Point Road and proceed into the Paxtuxent River Naval
Airtest Station, then proceed 1.2 miles (1.9 km) and turn right at the first
light past the Navy Exchange onto Tate Road, then proceed 2.5 miles (4.0 km) and
turn left at the stop sign on the runway track onto Johnson Road, proceed 1.0
mile (1.6 km) and turn right at the target support entrance road and proceed
through the gate to the TSD Target Support Section parking lot. The bench marks
are along the road leading to the gate to the parking lot. The tide gage and
staff were located on the southernmost pier behind the parking lot.
T I D A L B E N C H M A R K S
PRIMARY BENCH MARK STAMPING: 7385 A 1981
MONUMENTATION: Survey Disk VM#: 3216
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Bulkhead
The bench mark is set flush in the top of the concrete bulkhead, 117 feet (36 m)
south of the south edge of the northernmost seawall which forms the Navy
Seaplane basin, 88.5 feet (27.0 m) east of SE corner of parking lot for the TSD
Target Support Section just beyond end of the wooden pier which runs over a
concrete bulkhead, 3.0 feet (0.9 m) south of the north edge of a concrete
bulkhead, 2.5 feet (0.8 m) west of the east end of the concrete bulkhead and 1.0
foot (0.3 m) north of the south edge of the concrete bulkhead.
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 2 of 5
PUBLICATION DATE: 12/26/1985
Station ID: 8577385 SUPERCEDED DATE: 04/21/2003
Name: NAVY SEAPLANE BASIN, CHESAPEAKE BAY
MARYLAND
NOAA Chart: 12264 Latitude: 38° 16.3' N
USGS Quad: SOLOMONS ISLAND Longitude: 76° 23.8' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 7385 B 1981
MONUMENTATION: Survey Disk VM#: 3217
AGENCY: PID:
SETTING CLASSIFICATION: Concrete Seawall
The bench mark is set flush in the top of the northernmost concrete seawall in a
seawall that forms the Navy Seaplane Basin, 184 feet (56 m) ESE of the east edge
of the parking lot for TDS Target Support Section, 49.7 feet (15.1 m) ESE of the
corner of the TSD Target Support Section building, 24.0 feet (7.3 m) south of
the north edge of the seawall, 3.6 feet (1.1 m) east of the east edge of the
southwesternmost concrete footing for the tower on the seawall, 2.7 feet (0.8 m)
west of the west edge of the southeasternmost footing for the tower, and 2.0
feet (0.6 m) north of the south edge of the bulkhead.
BENCH MARK STAMPING: 7385 C 1981
MONUMENTATION: Survey Disk VM#: 3218
AGENCY: PID:
SETTING CLASSIFICATION: Stainless Steel Rod
The bench mark is in line with power poles on the north side of, and parallel to
the road leading to the TSD Target Support Section, 70 feet (21 m) west of the
SW corner of the TSD Target Support Section building, 49.5 feet (15 m) NE of the
center of the entrance gate to the TSD Target Support Section parking lot, 34
feet (10 m) south of telephone pole #9, 23 feet (7 m) east of the easternmost of
the double set of poles which holds a transformer, and 10.5 feet (3.2 m) NW of
the edge of the parking lot which curves from north to west. The bench mark is
crimped to the top of a stainless steel rod driven to refusal at a depth of 62
feet (19 m).
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 3 of 5
PUBLICATION DATE: 12/26/1985
Station ID: 8577385 SUPERCEDED DATE: 04/21/2003
Name: NAVY SEAPLANE BASIN, CHESAPEAKE BAY
MARYLAND
NOAA Chart: 12264 Latitude: 38° 16.3' N
USGS Quad: SOLOMONS ISLAND Longitude: 76° 23.8' W
T I D A L B E N C H M A R K S
BENCH MARK STAMPING: 7385 D 1981
MONUMENTATION: Survey Disk VM#: 3219
AGENCY: PID:
SETTING CLASSIFICATION: Stainless Steel Rod
The bench mark is 250 feet (76 m) west of Bench Mark 7385 C 1981, 20.4 feet (6.2
m) north of the centerline of the road leading to the TSD Target Support
Section, 14 feet (4 m) south of the third power pole in a line west from the TSD
Target Support Section and 2.0 feet (0.6 m) south of an NGS Survey sign. The
bench mark is crimped to the top of a stainless steel rod driven to refusal at a
depth of 48 feet (15 m) capped and accessible with a pry bar and a 9/16-inch
wrench.
BENCH MARK STAMPING: 7385 E 1981
MONUMENTATION: Survey Disk VM#: 3220
AGENCY: PID:
SETTING CLASSIFICATION: Stainless Steel Rod
The bench mark is 164 feet (50 m) north of the centerline of the road leading to
the TSD Target Support Section, 142 feet (43 m) WNW of the NW corner of the TSD
Target Support Section building, 123 feet (37 m) SW of a 100-foot (30 m) tall
communication pole, 1.5 feet (0.5 m) south of an NGS survey sign. The bench
mark is crimped to the top of a stainless steel rod driven to refusal at 54 feet
(16 m).
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 4 of 5
PUBLICATION DATE: 12/26/1985
Station ID: 8577385 SUPERCEDED DATE: 04/21/2003
Name: NAVY SEAPLANE BASIN, CHESAPEAKE BAY
MARYLAND
NOAA Chart: 12264 Latitude: 38° 16.3' N
USGS Quad: SOLOMONS ISLAND Longitude: 76° 23.8' W
T I D A L D A T U M S
Tidal datums at NAVY SEAPLANE BASIN, CHESAPEAKE BAY based on:
LENGTH OF SERIES: 1 MONTH
TIME PERIOD: SEPTEMBER 1981
TIDAL EPOCH: 1960-1978
CONTROL TIDE STATION: 8577330 SOLOMONS
Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET:
HIGHEST OBSERVED WATER LEVEL (09/04/1981) = 2.54
MEAN HIGHER HIGH WATER MHHW = 1.44
MEAN HIGH WATER MHW = 1.28
MEAN TIDE LEVEL MTL = 0.72
MEAN LOW WATER MLW = 0.16
MEAN LOWER LOW WATER MLLW = 0.00
LOWEST OBSERVED WATER LEVEL (10/08/1981) = -0.75
Bench Mark Elevation Information In FEET above:
Stamping or Designation MLLW MHW
7385 A 1981 7.17 5.89
7385 B 1981 7.20 5.92
7385 C 1981 6.83 5.55
7385 D 1981 8.37 7.09
7385 E 1981 11.36 10.08
U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Ocean Service
Page 5 of 5
PUBLICATION DATE: 12/26/1985
Station ID: 8577385 SUPERCEDED DATE: 04/21/2003
Name: NAVY SEAPLANE BASIN, CHESAPEAKE BAY
MARYLAND
NOAA Chart: 12264 Latitude: 38° 16.3' N
USGS Quad: SOLOMONS ISLAND Longitude: 76° 23.8' 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 (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 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.