U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 7 Station ID: 8635750 PUBLICATION DATE: 04/21/2003 Name: LEWISETTA, POTOMAC RIVER VIRGINIA NOAA Chart: 12233 Latitude: 37° 59.7' N USGS Quad: HEATHSVILLE Longitude: 76° 27.9' W To reach the tidal bench marks from the intersection of State Highway 360 and County Road 624 south of Calao, proceed 9.8 km (6.1 miles) north on County Road 624 to the Lewisetta Marina and General Store. The bench marks are located in the vicinity of the marina and store and the tide gage is located on the fuel pier. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: R 462 1971 DESIGNATION: R 462 MONUMENTATION: Bench Mark disk VM#: 493 AGENCY: National Geodetic Survey (NGS) PID#: GV0156 SETTING CLASSIFICATION: Metal rod on base plate encased in 4 inch Orangeburg pipe The primary bench mark is a disk located 52.2 m (171.4 ft) SE of the east corner of the Lewisetta General Store, 37.8 m (124.0 ft) south of the centerline of a gravel road, 16.67 m (54.7 ft) SW of the SW corner of a one story white house, 5.48 m (18.0 ft) NW of the high water line of the Coan River, 2.59 m (8.5 ft) WNW of a 0.41 m (1.3 ft) diameter cottonwood tree, and 0.21 m (0.7 ft) SE of a fiberglass witness post. The bench mark is 0.30 m (1.0 ft) below grade, crimped to a 1.2 m (4 ft) section of copper clad rod attached to a metal base plate, and encased in a 4 inch orangeburg pipe. BENCH MARK STAMPING: NO 2 1959 DESIGNATION: 863 5750 TIDAL 2 MONUMENTATION: Tidal Station disk VM#: 494 AGENCY: US Coast and Geodetic Survey (USC&GS) PID#: GV0157 SETTING CLASSIFICATION: Concrete monument The bench mark is a disk set in a concrete monument on the south side of the aluminum boat and storage shed at the Lewisetta Marina, 33.68 m (110.5 ft) north of the west corner of the boat rental building, 32.98 m (108.2 ft) NW of the west corner of the Lewisetta General Store, 9.81 m (32.2 ft) west of the south corner of the storage shed, and 9.63 m (31.6 ft) SE of the south corner of a concrete block pump house.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 7 Station ID: 8635750 PUBLICATION DATE: 04/21/2003 Name: LEWISETTA, POTOMAC RIVER VIRGINIA NOAA Chart: 12233 Latitude: 37° 59.7' N USGS Quad: HEATHSVILLE Longitude: 76° 27.9' W T I D A L B E N C H M A R K S BENCH MARK STAMPING: Q 462 1971 DESIGNATION: Q 462 MONUMENTATION: Bench Mark disk VM#: 495 AGENCY: National Geodetic Survey (NGS) PID#: GV0155 SETTING CLASSIFICATION: Concrete monument The bench mark is a disk set in a concrete post located on the east side of a two story metal building, 37.64 m (123.5 ft) NW of the centerline of County Road 624, 14.39 m (47.2 ft) SE of the NE corner of the building, 10.76 m (35.3 ft) ENE of the SE corner of the building, and 0.03 m (0.1 ft) below grade. BENCH MARK STAMPING: NO 5 1973 DESIGNATION: 863 5750 TIDAL 5 MONUMENTATION: Tidal Station disk VM#: 496 AGENCY: National Ocean Survey (NOS) PID: SETTING CLASSIFICATION: Concrete step The bench mark is a disk set in the bottom concrete step of the boat rental building located in the vicinity of the fuel pier at the Lewisetta Marina, 20.60 m (67.6 ft) SW of the SW face of the Lewisetta General Store, 13.38 m (43.9 ft) WNW of the steel sign post for the gas pumps, 5.91 m (19.4 ft) north of the shore end of the fuel pier, 2.10 m (6.9 ft) ESE of the WNW corner of the bottom step of the boat rental building, and 0.03 m (0.1 ft) above ground.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 7 Station ID: 8635750 PUBLICATION DATE: 04/21/2003 Name: LEWISETTA, POTOMAC RIVER VIRGINIA NOAA Chart: 12233 Latitude: 37° 59.7' N USGS Quad: HEATHSVILLE Longitude: 76° 27.9' W T I D A L B E N C H M A R K S BENCH MARK STAMPING: 5750 G 1978 DESIGNATION: 863 5750 G MONUMENTATION: Tidal Station disk VM#: 498 AGENCY: National Ocean Survey (NOS) PID: SETTING CLASSIFICATION: Stainless steel rod The bench mark is a disk located along the west side of State Road 6211 in the vicinity of the Lewisetta Marina, 40.69 m (133.5 ft) east of the NE corner of the two story metal boat repair building, 22.89 m (75.1 ft) SE of the SE corner of a white one story house, 5.79 m (19.0 ft) west of the centerline of State Road 6211, and 0.61 m (2.0 ft) west of a birch tree. The bench mark is 0.40 m (1.3 ft) below ground, crimped to a stainless steel rod driven 14.6 m (48 ft) to refusal, and encased in a 5 inch PVC pipe with concrete kickblock. BENCH MARK STAMPING: 5750 H 1978 DESIGNATION: 863 5750 H MONUMENTATION: Tidal Station disk VM#: 499 AGENCY: National Ocean Survey (NOS) PID: SETTING CLASSIFICATION: Stainless steel rod The bench mark is a disk located at the east corner of the aluminum boat and storage shed at the Lewisetta Marina, 30.17 m (99.0 ft) south of the east corner of a wooden boat shed, 26.36 m (86.5 ft) NW of the NW corner of the Lewisetta General Store, and 0.37 m (1.2 ft) NE of the east corner of the storage shed. The bench mark is crimped to a stainless steel rod driven 14.6 m (48 ft) to refusal, and encased in a PVC pipe with concrete kickblock.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 7 Station ID: 8635750 PUBLICATION DATE: 04/21/2003 Name: LEWISETTA, POTOMAC RIVER VIRGINIA NOAA Chart: 12233 Latitude: 37° 59.7' N USGS Quad: HEATHSVILLE Longitude: 76° 27.9' W T I D A L B E N C H M A R K S BENCH MARK STAMPING: 5750 J 1979 DESIGNATION: 863 5750 J MONUMENTATION: Tidal Station disk VM#: 500 AGENCY: National Ocean Survey (NOS) PID: SETTING CLASSIFICATION: Stainless steel rod The bench mark is a disk located on the east side of County Road 624 at the Lewisetta Chapel, 16.09 m (52.8 ft) NW of the north corner of the Chapel, 5.21 m (17.1 ft) east of the centerline of County Road 624, and 0.49 m (1.6 ft) west of a utility pole. The bench mark is crimped to a stainless steel rod driven 11.0 m (36 ft) to refusal, and encased in a 4 inch PVC pipe with concrete kickblock. BENCH MARK STAMPING: 5750 K 1980 DESIGNATION: 863 5750 K MONUMENTATION: Tidal Station disk VM#: 501 AGENCY: National Ocean Survey (NOS) PID: SETTING CLASSIFICATION: Galvanized steel rod The bench mark is a disk located in the Y junction of County Road 624 and a dirt road near the concrete boat ramp at the Lewisetta Marina, 25.51 m (83.7 ft) ENE of the NE end of the ramp, 7.35 m (24.1 ft) NW of the centerline of County Road 624, 4.23 m (13.9 ft) NNE of the centerline of the south part of the dirt road, and 4.11 m (13.5 ft) south of the centerline of the north part of the dirt road. The bench mark is crimped to a galvanized steel rod driven 14.6 m (48 ft) to refusal, and encased in a PVC pipe with concrete kickblock.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 7 Station ID: 8635750 PUBLICATION DATE: 04/21/2003 Name: LEWISETTA, POTOMAC RIVER VIRGINIA NOAA Chart: 12233 Latitude: 37° 59.7' N USGS Quad: HEATHSVILLE Longitude: 76° 27.9' W T I D A L B E N C H M A R K S BENCH MARK STAMPING: 5750 M 1986 DESIGNATION: 863 5750 M MONUMENTATION: Tidal Station disk VM#: 1624 AGENCY: National Ocean Service (NOS) PID: SETTING CLASSIFICATION: Stainless steel rod The bench mark is a disk located along the west side of County Road 624 in the vicinity of the Lewisetta Marina, 27.74 m (91.0 ft) south of a gravel road leading to a tan house, 7.01 m (23.0 ft) west of the centerline of County Road 624, 3.41 m (11.2 ft) east of TTCO power pole #136 branded 7-25, and 0.30 m (1.0 ft) east of a NOAA witness post. The bench mark is 0.06 m (0.2 ft) below ground, crimped to a stainless steel rod driven 11.0 m (36 ft) to refusal, and encased in a PVC pipe with concrete kickblock. BENCH MARK STAMPING: NO 3 1959 DESIGNATION: 863 5750 TIDAL 3 MONUMENTATION: Tidal Station disk VM#: 13557 AGENCY: US Coast and Geodetic Survey (USC&GS) PID: SETTING CLASSIFICATION: Concrete monument The bench mark is a disk set in a concrete monument on top of a small mound located at the 'Y' junction of a dirt road near the ramp at the Lewisetta Marina, 25.51 m (83.7 ft) ENE of the NE end of the concrete boat ramp, 7.32 m (24.0 ft) NW of the centerline of County Road 624, 4.21 m (13.8 ft) NNE of the centerline of the south part of the dirt driveway, and 0.61 m (2.0 ft) east of Bench Mark 5750 K 1980.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 6 of 7 Station ID: 8635750 PUBLICATION DATE: 04/21/2003 Name: LEWISETTA, POTOMAC RIVER VIRGINIA NOAA Chart: 12233 Latitude: 37° 59.7' N USGS Quad: HEATHSVILLE Longitude: 76° 27.9' W T I D A L D A T U M S Tidal datums at LEWISETTA, POTOMAC RIVER based on: LENGTH OF SERIES: 19 Years TIME PERIOD: January 1983 - December 2001 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: HIGHEST OBSERVED WATER LEVEL (02/05/1998) = 1.170 MEAN HIGHER HIGH WATER (MHHW) = 0.458 MEAN HIGH WATER (MHW) = 0.415 NORTH AMERICAN VERTICAL DATUM-1988 (NAVD) = 0.253 MEAN SEA LEVEL (MSL) = 0.230 MEAN TIDE LEVEL (MTL) = 0.226 MEAN LOW WATER (MLW) = 0.036 MEAN LOWER LOW WATER (MLLW) = 0.000 LOWEST OBSERVED WATER LEVEL (04/05/1975) = -0.869 National Geodetic Vertical Datum (NGVD 29) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW R 462 1971 1.420 1.004 NO 2 1959 1.289 0.874 Q 462 1971 1.216 0.801 NO 5 1973 1.474 1.059 5750 G 1978 1.046 0.631 5750 H 1978 1.192 0.776 5750 J 1979 1.341 0.925 5750 K 1980 1.564 1.149 5750 M 1986 1.293 0.877 NO 3 1959 1.543 1.127
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 7 of 7 Station ID: 8635750 PUBLICATION DATE: 04/21/2003 Name: LEWISETTA, POTOMAC RIVER VIRGINIA NOAA Chart: 12233 Latitude: 37° 59.7' N USGS Quad: HEATHSVILLE Longitude: 76° 27.9' 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.