U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 8440273 PUBLICATION DATE: 09/17/2003 Name: SALISBURY POINT MA NOAA Chart: 13282 Latitude: 42° 50.3' N ( 42.83830) USGS Quad: NEWBURYPORT WEST Longitude: 70° 54.5' W ( -70.90830) To reach the bench marks from the Amesbury exit (#55) of Interstate Highway 495, proceed east on State Road 110 for 1.8 km (1.1 mi) to Merrill Street, then SW on Merrill Street for 1.3 km (0.8 mi) to the swing bridge over Merrimack River. The bench marks are near the bridge and Interstate Highway 495. The tide gage and staff were on the east bridge fender. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 0273 A 1989 DESIGNATION: 844 0273 A MONUMENTATION: Tidal Station disk VM#: 1443 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Bedrock OPUS PID: LATITUDE: 42° 50.3' N ( 42.83830) LONGITUDE: 70° 54.5' W ( -70.90830) The primary bench mark is a disk set flush in an outcropping of bedrock, 32 m (106 ft) NE of power pole #83/1 on the north side of Old Merrill Street, 9 m (29 ft) west of power pole #2, and 8 m (26 ft) NNW of the centerline of Old Merrill Street.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 Station ID: 8440273 PUBLICATION DATE: 09/17/2003 Name: SALISBURY POINT MA NOAA Chart: 13282 Latitude: 42° 50.3' N ( 42.83830) USGS Quad: NEWBURYPORT WEST Longitude: 70° 54.5' W ( -70.90830) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 4869 DESIGNATION: 844 0273 4869 MONUMENTATION: Survey disk VM#: 1444 AGENCY: Massachusetts Geodetic Survey (MAGS) IDB PID#: SETTING CLASSIFICATION: Concrete sidewalk OPUS PID: LATITUDE: 42° 50.3' N ( 42.83830) LONGITUDE: 70° 54.5' W ( -70.90830) The bench mark is a disk set flush in the concrete sidewalk at the NE end of the Interstate Highway 95 bridge (Whittier Memorial Bridge) over Merrimack River, 0.85 m (2.8 ft) east of the center of a manhole cover in the sidewalk, 0.67 m (2.2 ft) SW of the north end of the sidewalk, and 0.43 m (1.4 ft) NW of the face of the granite retaining wall. BENCH MARK STAMPING: DESIGNATION: 844 0273 NO STAMPING 1 MONUMENTATION: Survey disk VM#: 1445 AGENCY: Massachusetts DPW (MADPW) IDB PID#: SETTING CLASSIFICATION: Concrete abutment OPUS PID: LATITUDE: 42° 50.3' N ( 42.83830) LONGITUDE: 70° 54.5' W ( -70.90830) The bench mark is a disk set flush in the NE concrete abutment of the Main Street bridge over Merrimack River, 36 m (119 ft) south of the centerline of Old Merrill Street, 5 m (16 ft) east of the centerline of Main Street, and 4 m (13 ft) north of a steel power pole with electric meter on the east side of the bridge.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 8440273 PUBLICATION DATE: 09/17/2003 Name: SALISBURY POINT MA NOAA Chart: 13282 Latitude: 42° 50.3' N ( 42.83830) USGS Quad: NEWBURYPORT WEST Longitude: 70° 54.5' W ( -70.90830) T I D A L B E N C H M A R K S BENCH MARK STAMPING: DESIGNATION: 844 0273 NO STAMPING 2 MONUMENTATION: Survey disk VM#: 1446 AGENCY: Massachusetts DPW (MADPW) IDB PID#: SETTING CLASSIFICATION: Concrete abutment OPUS PID#: BBBJ42 LATITUDE: 42° 50.3' N ( 42.83830) LONGITUDE: 70° 54.5' W ( -70.90830) The bench mark is a disk set flush in the SW concrete abutment of the Main Street bridge over the Merrimack River, 4.60 m (15.1 ft) WSW of the centerline of Main Street, 4.08 m (13.4 ft) NNE of the north corner of the bridge tender's house, and 0.21 m (0.7 ft) NW of the SE edge of the abutment. BENCH MARK STAMPING: DESIGNATION: 844 0273 NO STAMPING 3 MONUMENTATION: Rivet VM#: 1447 AGENCY: Unknown IDB PID#: SETTING CLASSIFICATION: Concrete wing wall OPUS PID: LATITUDE: 42° 50.3' N ( 42.83830) LONGITUDE: 70° 54.5' W ( -70.90830) The bench mark is set flush in the SE concrete wingwall of the Essex-Merrimack suspension bridge on the south side of Deer Island, 53.98 m (177.1 ft) north of the NW corner of the residence at #3 Spofford Street, and 7.07 m (23.2 ft) east of the centerline of Spofford Street.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 8440273 PUBLICATION DATE: 09/17/2003 Name: SALISBURY POINT MA NOAA Chart: 13282 Latitude: 42° 50.3' N ( 42.83830) USGS Quad: NEWBURYPORT WEST Longitude: 70° 54.5' W ( -70.90830) T I D A L D A T U M S Tidal datums at SALISBURY POINT based on: LENGTH OF SERIES: 3 MONTHS TIME PERIOD: July 1989 - September 1989 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 8440466 NEWBURYPORT, MERRIMACK RIVER Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 2.525 MEAN HIGH WATER MHW = 2.387 MEAN SEA LEVEL MSL = 1.227 MEAN TIDE LEVEL MTL = 1.223 MEAN LOW WATER MLW = 0.058 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 0273 A 1989 7.502 5.115 4869 20.585 18.198 844 0273 NO STAMPING 1 8.490 6.103 844 0273 NO STAMPING 2 8.360 5.973 844 0273 NO STAMPING 3 10.490 8.103
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 8440273 PUBLICATION DATE: 09/17/2003 Name: SALISBURY POINT MA NOAA Chart: 13282 Latitude: 42° 50.3' N ( 42.83830) USGS Quad: NEWBURYPORT WEST Longitude: 70° 54.5' W ( -70.90830) 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.