U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 6 PUBLICATION DATE: 03/28/1988 Station ID: 8574680 SUPERCEDED DATE: 04/21/2003 Name: BALTIMORE (FORT MCHENRY), PATAPSCO RIVER MARYLAND NOAA Chart: 12281 Latitude: 39° 16.0' N USGS Quad: BALTIMORE EAST Longitude: 76° 34.7' W To reach the tidal bench marks from the north bound Baltimore-Washington Expressway (State Highway 295) take the Water View exit east to State Highway 2 (Hanover Street), proceed north on Hanover Street for 1.5 miles (2.4 km) to Fort Avenue, turn right and travel east on Fort Avenue for 1.8 miles (2.9 km) to the entrance of Fort McHenry, turn left onto Wallace Avenue, then right again onto Nimitz Drive and then left onto Halsey Road to its end, turn right and continue past a gate to the U.S. Corps of Engineers (COE) compound. The bench marks are located in the U.S. Naval Reserve compound, the COE compound, and on the Fort McHenry grounds. The tide gage and staff are located on the COE pier. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 32 1922 MONUMENTATION: Survey Disk VM#: 434 AGENCY: PID#: JV0586 SETTING CLASSIFICATION: Granite Sill The bench mark is set in the top of a granite door sill on the west side of the U.S. Naval Reserve Center Building, 65.1 feet (19.8 m) NE of the SW corner of the building, 33.0 feet (10.1 m) SE of the centerline of Halsey Road, and 1.4 feet (0.4 m) above the sidewalk. BENCH MARK STAMPING: 25 1919 MONUMENTATION: Survey Disk VM#: 427 AGENCY: PID#: JV0583 SETTING CLASSIFICATION: Concrete Monument The bench mark is set in the top of a concrete monument in the COE compound, 46.3 feet (14.1 m) east of the NE corner of the COE soil laboratory (a single story structure with yellow siding), 38 feet (12 m) south of the edge of the sea wall, and 0.5 foot (0.2 m) above the ground.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 6 PUBLICATION DATE: 03/28/1988 Station ID: 8574680 SUPERCEDED DATE: 04/21/2003 Name: BALTIMORE (FORT MCHENRY), PATAPSCO RIVER MARYLAND NOAA Chart: 12281 Latitude: 39° 16.0' N USGS Quad: BALTIMORE EAST Longitude: 76° 34.7' W T I D A L B E N C H M A R K S BENCH MARK STAMPING: 27 1922 MONUMENTATION: Survey Disk VM#: 429 AGENCY: PID#: JV0579 SETTING CLASSIFICATION: Granite Foundation The bench mark is set in the center of an octagon shaped granite cannon base at the easternmost point of the star shaped fort at Fort McHenry grounds, 150 feet (46 m) ESE of the fort flagpole, 5.5 feet (1.7 m) ESE of a pile of cannon balls, and 0.4 foot (0.1 m) east of the west edge of the base. BENCH MARK STAMPING: 28 1922 MONUMENTATION: Survey Disk VM#: 430 AGENCY: PID#: JV0580 SETTING CLASSIFICATION: Concrete Foundation The bench mark is set in the east corner of the 3-foot (1 m) square concrete sub-base on the east leg of a range beacon near the east end of the Fort McHenry grounds, 53.7 feet (16.4 m) south of the SW leg of an electric meter box, 41.8 feet (12.7 m) WNW of the offshore edge of the sea wall, 1.1 feet (0.3 m) east of the east leg of the beacon, and 0.4 foot (0.1 m) below the ground. BENCH MARK STAMPING: 29 1922 MONUMENTATION: Survey Disk VM#: 431 AGENCY: PID#: JV0582 SETTING CLASSIFICATION: Granite Sea Wall The bench mark is set in the sea wall cap in the COE compound, 61.3 feet (18.7 m) NE of the doorway of Building 2609, 26.6 feet (8.1 m) SE of the centerline of the fire boat pier, and 1 foot (0.3 m) south of the north edge of the sea wall cap.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 6 PUBLICATION DATE: 03/28/1988 Station ID: 8574680 SUPERCEDED DATE: 04/21/2003 Name: BALTIMORE (FORT MCHENRY), PATAPSCO RIVER MARYLAND NOAA Chart: 12281 Latitude: 39° 16.0' N USGS Quad: BALTIMORE EAST Longitude: 76° 34.7' W T I D A L B E N C H M A R K S BENCH MARK STAMPING: 30 1922 MONUMENTATION: Survey Disk VM#: 432 AGENCY: PID#: JV0584 SETTING CLASSIFICATION: Granite Sill The bench mark is set in the top of a granite sill in the COE compound, 20 feet (6 m) west of the centerline of a paved road between the fire department barracks and soil laboratory, 6.7 feet (2.0 m) south of the NE corner of a warehouse, and 3 feet (1 m) above the ground. BENCH MARK STAMPING: 31 1922 MONUMENTATION: Survey Disk VM#: 433 AGENCY: PID#: JV0585 SETTING CLASSIFICATION: Granite Sill The bench mark is set in the top of a granite door sill of the U.S. Naval Reserve Center boiler room at the north end of Halsey Road, 44.7 feet (13.6 m) north of the NW corner of the main Naval Reserve Center Building, 18.0 feet (5.5 m) NNE of the centerline of the entrance road to the COE compound, 4.6 feet (1.4 m) NW of the edge of the top step, and 3 feet (1 m) above the ground. BENCH MARK STAMPING: 35 1922 MONUMENTATION: Survey Disk VM#: 435 AGENCY: PID#: JV0576 SETTING CLASSIFICATION: Granite Sill The bench mark is set in the main entrance door sill to the Southern States Coop Mills office building at the intersection of East Fort Avenue and Wallace Street, 127 feet (39 m) SSW of the centerline of Fort Avenue, 37.8 feet (11.5 m) WNW of the brick wall around the Fort McHenry grounds, and 0.5 foot (0.2 m) SE of the west side of the entrance way to the building.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 6 PUBLICATION DATE: 03/28/1988 Station ID: 8574680 SUPERCEDED DATE: 04/21/2003 Name: BALTIMORE (FORT MCHENRY), PATAPSCO RIVER MARYLAND NOAA Chart: 12281 Latitude: 39° 16.0' N USGS Quad: BALTIMORE EAST Longitude: 76° 34.7' W T I D A L B E N C H M A R K S BENCH MARK STAMPING: 4680 A 1980 MONUMENTATION: Survey Disk VM#: 436 AGENCY: PID: SETTING CLASSIFICATION: Galvanized Steel Rod The bench mark is located in the COE compound in line with a line of maple trees, 122.9 feet (37.5 m) NNW of a flagpole, 90.6 feet (27.6 m) north of the NW corner of the office building, and 42.1 feet (12.8 m) SW of a power pole at the end of the pier. The bench mark is 0.1 foot (0.03 m) below the ground, crimped to a galvanized steel rod driven 37 feet (11 m) to refusal. BENCH MARK STAMPING: NO STAMPING 1 MONUMENTATION: Survey Disk VM#: 437 AGENCY: PID#: JV0578 SETTING CLASSIFICATION: Concrete Monument The bench mark is set in the top of a concrete monument in the grassy area between the Francis Scott Key memorial statue and the visitors center on the For McHenry grounds, 292.0 feet (89.0 m) east of the east face of the bottom step of the memorial, 258.0 feet (78.6 m) WSW of the SW corner of the visitors center, and 2.0 feet (0.6 m) above the ground. The monument bears the inscription UNITED STATES COAST AND GEODETIC SURVEY BASIC BENCH MARK.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 6 PUBLICATION DATE: 03/28/1988 Station ID: 8574680 SUPERCEDED DATE: 04/21/2003 Name: BALTIMORE (FORT MCHENRY), PATAPSCO RIVER MARYLAND NOAA Chart: 12281 Latitude: 39° 16.0' N USGS Quad: BALTIMORE EAST Longitude: 76° 34.7' W T I D A L D A T U M S Tidal datums at BALTIMORE (FORT MCHENRY), PATAPSCO RIVER based on: LENGTH OF SERIES: 19 YEARS TIME PERIOD: 1960-1978 TIDAL EPOCH: 1960-1978 CONTROL TIDE STATION: Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET: HIGHEST OBSERVED WATER LEVEL (08/23/1933) = 7.90 MEAN HIGHER HIGH WATER (MHHW) = 1.66 MEAN HIGH WATER (MHW) = 1.35 MEAN TIDE LEVEL (MTL) = 0.80 * NATIONAL GEODETIC VERTICAL DATUM-1929 (NGVD) = 0.28 MEAN LOW WATER (MLW) = 0.24 MEAN LOWER LOW WATER (MLLW) = 0.00 BALTIMORE CITY DATUM (BCD) = -0.57 LOWEST OBSERVED WATER LEVEL (01/24/1908) = -4.90 * NGVD reference based on adjustment of 1972 AND NOS levels of 1984. National Geodetic Vertical Datum (NGVD 29) Bench Mark Elevation Information In FEET above: Stamping or Designation MLLW MHW 32 1922 6.49 5.14 25 1919 6.16 4.81 27 1922 31.11 29.76 28 1922 7.14 5.79 29 1922 4.83 3.48 30 1922 9.46 8.11 31 1922 6.44 5.09 35 1922 27.39 26.04 4680 A 1980 5.37 4.02 NO STAMPING 1 31.47 30.12
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 6 of 6 PUBLICATION DATE: 03/28/1988 Station ID: 8574680 SUPERCEDED DATE: 04/21/2003 Name: BALTIMORE (FORT MCHENRY), PATAPSCO RIVER MARYLAND NOAA Chart: 12281 Latitude: 39° 16.0' N USGS Quad: BALTIMORE EAST Longitude: 76° 34.7' 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.