U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 8443725 PUBLICATION DATE: 10/07/2003 Name: CHELSEA ST. BRIDGE, CHELSEA RIVER MA NOAA Chart: 13272 Latitude: 42° 23.2' N ( 42.38670) USGS Quad: BOSTON NORTH Longitude: 71° 1.4' W ( -71.02330) To reach the tidal bench marks from the intersection of I-93 and Highway 16 in Boston, proceed east on Highway 16 for 7.1 km (4.4 mi) to Broadway (Highway 107), take the exit for Broadway and continue 0.3 km (0.2 mi) to Eastern Avenue, bear left and proceed south on Eastern Avenue for 1.6 km (1.0 mi) to Chelsea Street, then bear left and continue south on Chelsea Street for 0.3 km (0.2 mi) to the Chelsea Street Bridge. The bench marks are along Chelsea Street south of the bridge, and the tide gage was located on the bumper pier below the bridge. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 3725 A 2002 DESIGNATION: 844 3725 A MONUMENTATION: Tidal Station disk VM#: 16725 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Overhead doorsill OPUS PID: LATITUDE: 42° 23.2' N ( 42.38670) LONGITUDE: 71° 1.4' W ( -71.02330) The primary bench mark is a disk set in the south end of a concrete sill for an overhead door on the west side of the I.N. Caruso Pumping Station at 601 Chelsea Street, 11.85 m (38.9 ft) south of the flagpole in front of the station, 5.50 m (18.0 ft) east of the south gate post of a chain link fence along Chelsea Street, and 2.17 m (7.1 ft) north of the SW corner of the station.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 Station ID: 8443725 PUBLICATION DATE: 10/07/2003 Name: CHELSEA ST. BRIDGE, CHELSEA RIVER MA NOAA Chart: 13272 Latitude: 42° 23.2' N ( 42.38670) USGS Quad: BOSTON NORTH Longitude: 71° 1.4' W ( -71.02330) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 3725 B 2002 DESIGNATION: 844 3725 B MONUMENTATION: Tidal Station disk VM#: 16726 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Loading doorsill OPUS PID: LATITUDE: 42° 23.2' N ( 42.38670) LONGITUDE: 71° 1.4' W ( -71.02330) The bench mark is a disk set in the NE side of the concrete foundation sill for the door of the largest of three loading bays at Eagle Global Logistics located at 160 McClellan Highway, 16.2 m (53 ft) SW of the grey office door, 14.60 m (47.9 ft) north of the NE corner of a loading ramp, and 0.16 m (0.5 ft) SSW of a bumper guard. BENCH MARK STAMPING: NO 1 1945 DESIGNATION: 844 3725 TIDAL 1 MONUMENTATION: Tidal Station disk VM#: 16727 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: SETTING CLASSIFICATION: Retaining wall OPUS PID: LATITUDE: 42° 23.2' N ( 42.38670) LONGITUDE: 71° 1.4' W ( -71.02330) In Chelsea, near the SW corner of the Chelsea Street Bridge over the Chelsea River, the bench mark is a disk set in the concrete retaining wall on the west side of the bridge, 14.70 m (48.2 ft) NW of the traffic light foundation, 14.34 m (47.0 ft) south of the center of the door to the bridge tender office, 6.36 m (20.9 ft) NW of the bridge gate foundation on the west side of the bridge, and 2.45 m (8.0 ft) west of the steel girder for the bridge.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 8443725 PUBLICATION DATE: 10/07/2003 Name: CHELSEA ST. BRIDGE, CHELSEA RIVER MA NOAA Chart: 13272 Latitude: 42° 23.2' N ( 42.38670) USGS Quad: BOSTON NORTH Longitude: 71° 1.4' W ( -71.02330) T I D A L B E N C H M A R K S BENCH MARK STAMPING: DESIGNATION: 844 3725 MGS 3047 MONUMENTATION: Rivet VM#: 16728 AGENCY: Massachusetts Geodetic Survey (MGS) IDB PID#: SETTING CLASSIFICATION: Granite step OPUS PID: LATITUDE: 42° 23.2' N ( 42.38670) LONGITUDE: 71° 1.3' W ( -71.02170) In Chelsea, near the SE corner of the Chelsea Street Bridge over the Chelsea River, the bench mark is a monel rivet set in the granite step along the center of the south side of the Massachusetts Water Resources Authority Sewage Division building, 52.99 m (173.9 ft) NE of the center of the door painted black of the I.N. Caruso Pumping Station, 18.83 m (61.8 ft) NW of the fire hydrant protected by two bollards, and 16.20 m (53.1 ft) NW of power pole number 39-1-3X. BENCH MARK STAMPING: DESIGNATION: 844 3725 USE MONUMENTATION: Survey disk VM#: 16729 AGENCY: US Army Corps of Engineers (USE) IDB PID#: SETTING CLASSIFICATION: Doorsill OPUS PID: LATITUDE: 42° 23.1' N ( 42.38500) LONGITUDE: 71° 1.3' W ( -71.02170) In Chelsea, near the Chelsea Street Bridge over the Chelsea River, the bench mark is a disk set in the concrete foundation for the ramp at the entrance to the double doors located at the NW corner of the Massachusetts Water Resources Authority Sewage Division building, 31.75 m (104.2 ft) east of the NE corner of the metal light post with two lights, 13.20 m (43.3 ft) NE of power pole number 1-64-1A, and 12.98 m (42.6 ft) NE of a double door just SW of the ramp.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 8443725 PUBLICATION DATE: 10/07/2003 Name: CHELSEA ST. BRIDGE, CHELSEA RIVER MA NOAA Chart: 13272 Latitude: 42° 23.2' N ( 42.38670) USGS Quad: BOSTON NORTH Longitude: 71° 1.4' W ( -71.02330) T I D A L D A T U M S Tidal datums at CHELSEA ST. BRIDGE, CHELSEA RIVER based on: LENGTH OF SERIES: 3 MONTHS TIME PERIOD: July 2002 - September 2002 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 = 3.155 MEAN HIGH WATER MHW = 3.019 MEAN SEA LEVEL MSL = 1.598 MEAN TIDE LEVEL MTL = 1.562 MEAN LOW WATER MLW = 0.104 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 3725 A 2002 5.819 2.800 3725 B 2002 5.188 2.169 NO 1 1945 4.628 1.609 844 3725 MGS 3047 4.784 1.765 844 3725 USE 4.915 1.896 Foot Notes:
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 8443725 PUBLICATION DATE: 10/07/2003 Name: CHELSEA ST. BRIDGE, CHELSEA RIVER MA NOAA Chart: 13272 Latitude: 42° 23.2' N ( 42.38670) USGS Quad: BOSTON NORTH Longitude: 71° 1.4' W ( -71.02330) 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.