U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 8630249 PUBLICATION DATE: 04/30/2003 Name: CHINCOTEAGUE, USCG STATION VA NOAA Chart: 12211 Latitude: 37° 55.9' N ( 37.93170) USGS Quad: CHINCOTEAGUE WEST Longitude: 75° 23.0' W ( -75.38330) To reach the tidal bench marks from the junction of State Highway 175 and Main Street in Chincoteague, proceed 0.45 km (0.3 mi) SW along Main Street, to the U.S. Coast Guard Base. The tide station was located at the northern edge of the U.S. Coast Guard south wharf at Chincoteague. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: NO 2 1962 DESIGNATION: 863 0249 TIDAL 2 MONUMENTATION: Tidal Station disk VM#: 3253 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: FW0136 SETTING CLASSIFICATION: flagpole base OPUS PID: LATITUDE: 37° 55.9' N ( 37.93170) LONGITUDE: 75° 22.9' W ( -75.38170) The primary bench mark is a disk set flush in the base of a flagepole, 61 m (200 ft) west of the centerline of Main Street, 11.58 m (38.0 ft) south of the north boundary (an east-west fence) of the Coast Guard Station. BENCH MARK STAMPING: NO 3 1962 DESIGNATION: 863 0249 TIDAL 3 MONUMENTATION: Tidal Station disk VM#: 3254 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: FW0135 SETTING CLASSIFICATION: Concrete porch OPUS PID: LATITUDE: 37° 55.8' N ( 37.93000) LONGITUDE: 75° 22.9' W ( -75.38170) The bench mark is a disk located on the SW corner of the concrete porch of Conant Brothers Hardware Store, and 8.23 m (27.0 ft) west of the centerline of Main Street.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 Station ID: 8630249 PUBLICATION DATE: 04/30/2003 Name: CHINCOTEAGUE, USCG STATION VA NOAA Chart: 12211 Latitude: 37° 55.9' N ( 37.93170) USGS Quad: CHINCOTEAGUE WEST Longitude: 75° 23.0' W ( -75.38330) T I D A L B E N C H M A R K S BENCH MARK STAMPING: TIDAL BM NO 4 1976 DESIGNATION: 863 0249 TIDAL 4 USE MONUMENTATION: Tidal Station disk VM#: 3256 AGENCY: US Army Corp of Engineers (USE) IDB PID#: FW0613 SETTING CLASSIFICATION: Concrete post OPUS PID: LATITUDE: 37° 55.8' N ( 37.93000) LONGITUDE: 75° 22.9' W ( -75.38170) The bench mark is a disk set in a concrete post, 11.43 m (37.5 ft) NW of the centerline of Main Street, 9.60 m (31.5 ft) SE of telephone pole Number NO 1 AH, 3.14 m (10.3 ft) SW of the centerline of an exit driveway, and 0.06 m (0.2 ft) below ground.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 8630249 PUBLICATION DATE: 04/30/2003 Name: CHINCOTEAGUE, USCG STATION VA NOAA Chart: 12211 Latitude: 37° 55.9' N ( 37.93170) USGS Quad: CHINCOTEAGUE WEST Longitude: 75° 23.0' W ( -75.38330) T I D A L B E N C H M A R K S BENCH MARK STAMPING: T 421 1963 DESIGNATION: T 421 MONUMENTATION: Bench Mark disk VM#: 3257 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: FW0139 SETTING CLASSIFICATION: Concrete post OPUS PID: LATITUDE: 37° 55.4' N ( 37.92330) LONGITUDE: 75° 23.4' W ( -75.39000) The bench mark is a disk set in a concrete post from the junction of State Highway 175 and Main Street at Chincoteague, 20.57 m (67.5 ft) WNW and across the street from the NW corner of a pink, one-story, block house, 7.93 m (26 ft) west of the centerline of Main Street, 1.68 m (5.5 ft) NNE of power pole No. 34 H-6MX, and 0.06 m (0.2 ft) above ground level. BENCH MARK STAMPING: 0249 A 1982 DESIGNATION: 863 0249 A MONUMENTATION: Tidal Station disk VM#: 3258 AGENCY: US Army Corp of Engineers (USE) IDB PID#: SETTING CLASSIFICATION: Concrete sea wall OPUS PID#: BBDL16 LATITUDE: 37° 55.0' N ( 37.91670) LONGITUDE: 75° 23.0' W ( -75.38330) The bench mark is a disk set in the concrete seawall at the U.S. Coast Guard Base, next to the boat ramp. 0.60 m (1.97 ft) NW of the SE corner of the seawall, 0.48 m (1.59 ft) west of the east edge of the seawall, and 0.39 m (1.29 ft) SE of the inside corner of the seawall
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 8630249 PUBLICATION DATE: 04/30/2003 Name: CHINCOTEAGUE, USCG STATION VA NOAA Chart: 12211 Latitude: 37° 55.9' N ( 37.93170) USGS Quad: CHINCOTEAGUE WEST Longitude: 75° 23.0' W ( -75.38330) T I D A L D A T U M S Tidal datums at CHINCOTEAGUE, USCG STATION based on: LENGTH OF SERIES: 12 MONTHS TIME PERIOD: February 1977 - January 1978 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 8638863 CHESAPEAKE BAY BRIDGE TUNNEL Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: HIGHEST OBSERVED WATER LEVEL (10/14/1977) = 1.136 MEAN HIGHER HIGH WATER MHHW = 0.561 MEAN HIGH WATER MHW = 0.511 North American Vertical Datum NAVD88 = 0.322 MEAN TIDE LEVEL MTL = 0.270 MEAN SEA LEVEL MSL = 0.269 MEAN LOW WATER MLW = 0.028 MEAN LOWER LOW WATER MLLW = 0.000 LOWEST OBSERVED WATER LEVEL (01/11/1978) = -0.702 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW NO 2 1962 1.353 0.842 NO 3 1962 1.529 1.018 TIDAL BM NO 4 1976 1.257 0.746 T 421 1963 1.097 0.586 0249 A 1982 1.035 0.524
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 8630249 PUBLICATION DATE: 04/30/2003 Name: CHINCOTEAGUE, USCG STATION VA NOAA Chart: 12211 Latitude: 37° 55.9' N ( 37.93170) USGS Quad: CHINCOTEAGUE WEST Longitude: 75° 23.0' W ( -75.38330) 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.