U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 4 Station ID: 8446166 PUBLICATION DATE: 02/05/2004 Name: DUXBURY, DUXBURY HARBOR MA NOAA Chart: 13253 Latitude: 42° 2.3' N ( 42.03830) USGS Quad: DUXBURY Longitude: 70° 40.2' W ( -70.67000) To reach the tidal bench marks from the intersection of State Routes 3 and 3A (Exit 10 on State Route 3), proceed north on State Route 3A for 4.5 km (2.8 mi) to Harrison Street, proceed east on Harrison Street for 1.8 km (1.1 mi) to the entrance of Duxbury Town Pier (at Washington Street). The bench marks are located along Washington Street and near the town pier. The tide gage and staff were located on the north end of the town pier. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 6166 A 1990 DESIGNATION: 844 6166 A MONUMENTATION: Tidal Station disk VM#: 1510 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Concrete sea wall OPUS PID: LATITUDE: 42° 2.3' N ( 42.03830) LONGITUDE: 70° 40.2' W ( -70.67000) The primary bench mark is a disk set in the sea wall located west of the town pier, 26.67 m (87.5 ft) east of the NE corner of a corrugated steel warehouse, 6.71 m (22 ft) north of NET&T utility pole #3, 0.12 m (0.4 ft) WSW of the east edge of the sea wall, and 0.18 m (0.6 ft) above the surface of the parking lot. BENCH MARK STAMPING: 29 AD 35.652 DESIGNATION: 29 AD MAGS MONUMENTATION: Survey disk VM#: 1511 AGENCY: Massachusetts Geodetic Survey (MAGS) IDB PID#: MY2140 SETTING CLASSIFICATION: Granite curb OPUS PID: LATITUDE: 42° 2.6' N ( 42.04330) LONGITUDE: 70° 40.3' W ( -70.67170) The bench mark is a disk set in a granite curb located at the SE corner of Washington Street and Fort Hill Lane, 5.43 m (17.8 ft) SSE of the centerline of Fort Hill Lane, 4.30 m (14.1 ft) ESE of the centerline of Washington Street, 2.07 m (6.8 ft) WNW of the NW corner of Bos'n Locker at #1 Fort Hill Lane, and 0.06 m (0.2 ft) above the street level.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 4 Station ID: 8446166 PUBLICATION DATE: 02/05/2004 Name: DUXBURY, DUXBURY HARBOR MA NOAA Chart: 13253 Latitude: 42° 2.3' N ( 42.03830) USGS Quad: DUXBURY Longitude: 70° 40.2' W ( -70.67000) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 29 AE DESIGNATION: 29 AE MAGS MONUMENTATION: Survey disk VM#: 1512 AGENCY: Massachusetts Geodetic Survey (MAGS) IDB PID#: MY2139 SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 42° 2.4' N ( 42.04000) LONGITUDE: 70° 40.3' W ( -70.67170) The bench mark is half of a survey disk set in a concrete monument located at the NE corner of the driveway at 500 Washington Street, 33.68 m (110.5 ft) NNE of NET&T utility pole #616, 4.08 m (13.4 ft) west of the centerline of Washington Street, and 0.40 m (1.3 ft) SSE of the south edge of the sidewalk on the north side of the driveway. NOTE: The original stamping was reported to have been 29 AE 11.060. BENCH MARK STAMPING: 29 AH DESIGNATION: 29 AH MONUMENTATION: Survey disk VM#: 1513 AGENCY: Massachusetts Geodetic Survey (MAGS) IDB PID#: SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 42° 2.3' N ( 42.03830) LONGITUDE: 70° 40.2' W ( -70.67000) The bench mark is a disk set in a concrete monument on the east side of Washington Street in front of the house at 381 Washington Street, 6.46 m (21.18 ft) NE of the junction of Washington and Winsor Streets, 19.29 m (63.3 ft) SW of the north corner of the house, 16.70 m (54.8 ft) NW of the west corner of the house, and 0.09 m (0.3 ft) below ground.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 4 Station ID: 8446166 PUBLICATION DATE: 02/05/2004 Name: DUXBURY, DUXBURY HARBOR MA NOAA Chart: 13253 Latitude: 42° 2.3' N ( 42.03830) USGS Quad: DUXBURY Longitude: 70° 40.2' W ( -70.67000) T I D A L D A T U M S Tidal datums at DUXBURY, DUXBURY HARBOR based on: LENGTH OF SERIES: 3 MONTHS TIME PERIOD: June 1990 - August 1990 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 8443970 BOSTON, BOSTON HARBOR Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 3.255 MEAN HIGH WATER MHW = 3.121 North American Vertical Datum NAVD88 = 1.807 MEAN SEA LEVEL MSL = 1.675 MEAN TIDE LEVEL MTL = 1.614 MEAN LOW WATER MLW = 0.106 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 6166 A 1990 4.271 1.150 29 AD 35.652 12.389 9.268 29 AE 4.922 1.801 29 AH 11.355 8.234
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 4 Station ID: 8446166 PUBLICATION DATE: 02/05/2004 Name: DUXBURY, DUXBURY HARBOR MA NOAA Chart: 13253 Latitude: 42° 2.3' N ( 42.03830) USGS Quad: DUXBURY Longitude: 70° 40.2' W ( -70.67000) 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.