U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 8464255 PUBLICATION DATE: 05/16/2003 Name: ROCKY HILL,CONNECTICUT RIVER CT NOAA Chart: 12377 Latitude: 41° 39.8' N ( 41.66330) USGS Quad: HARTFORD SOUTH Longitude: 72° 37.8' W ( -72.63000) To reach the tidal bench marks from Middleton proceed north on State Road 99 to Rocky Hill Fire Department Company #3, turn right on Old Forge Road and go 1.21 km (0.75 mi) to Dividend Road, turn left on Dividend Road and go 0.3 km (0.2 mi) to Evans Road, turn right on Evans Road and go 0.40 km (0.25 mi) to Rocky Hill Oil Company. The bench marks are on the oil company property and along the railroad tracks. The tide gage and staff were on the south side of the oil company fuel transfer dock behind the company grounds, reached through a locked company gate leading to the dock. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 1 1938 DESIGNATION: 846 4255 TIDAL 1 MONUMENTATION: Tidal Station disk VM#: 2257 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: SETTING CLASSIFICATION: Concrete pump house OPUS PID: LATITUDE: 41° 39.0' N ( 41.65000) LONGITUDE: 72° 37.6' W ( -72.62670) The primary bench mark is a disk set in the top of a 2.19 m (7.2 ft) square abandoned concrete pump house, 18 m (60 ft) north of the oil company fuel transfer dock, 5.09 m (16.7 ft) east of the river front fence on company grounds, 9 m (30 ft) south of the SE corner of a masonry building, and 3 m (9 ft) below the base of the fence.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 Station ID: 8464255 PUBLICATION DATE: 05/16/2003 Name: ROCKY HILL,CONNECTICUT RIVER CT NOAA Chart: 12377 Latitude: 41° 39.8' N ( 41.66330) USGS Quad: HARTFORD SOUTH Longitude: 72° 37.8' W ( -72.63000) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 2 1938 DESIGNATION: 846 4255 TIDAL 2 MONUMENTATION: Tidal Station disk VM#: 2258 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: SETTING CLASSIFICATION: Concrete railroad overpass OPUS PID: LATITUDE: 41° 39.0' N ( 41.65000) LONGITUDE: 72° 37.6' W ( -72.62670) The bench mark is a disk set in the NE corner of the concrete railroad overpass at the company entrance gate, 26 m (84 ft) south of a 2 m (6 ft) high Close Clearance sign which is 2 m (6 ft) west of the railroad, 24.17 m (79.3 ft) south of a 1 m (2 ft) high rail post which is 2 m (6 ft) west of the railroad, and 1.10 m (3.6 ft) east of the east rail. BENCH MARK STAMPING: 3 1938 DESIGNATION: 846 4255 TIDAL 3 MONUMENTATION: Tidal Station disk VM#: 2259 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: SETTING CLASSIFICATION: Concrete base OPUS PID: LATITUDE: 41° 39.0' N ( 41.65000) LONGITUDE: 72° 37.6' W ( -72.62670) The bench mark is a disk set in the SW corner of a 0.85 m (2.8 ft) square abandoned concrete railroad signal base, 138 ties north along the railroad from the centerline of Evans Road, 2 m (8 ft) west of the west rail, and 0.24 m (0.8 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 8464255 PUBLICATION DATE: 05/16/2003 Name: ROCKY HILL,CONNECTICUT RIVER CT NOAA Chart: 12377 Latitude: 41° 39.8' N ( 41.66330) USGS Quad: HARTFORD SOUTH Longitude: 72° 37.8' W ( -72.63000) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 4255 D 1987 DESIGNATION: 846 4255 D MONUMENTATION: Tidal Station disk VM#: 2260 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Concrete catch basin OPUS PID: LATITUDE: 41° 39.0' N ( 41.65000) LONGITUDE: 72° 37.6' W ( -72.62670) The bench mark is a disk set flush in the top of a concrete catch basin north of the south intersection of an inner spur pair of rails off the main line, SE of the building at 51 Belamose Avenue, 85 m (280 ft) north of the south intersection of the inner pair of rails, 4.82 m (15.8 ft) west of the west rail of the east pair of rails, and 3.08 m (10.1 ft) east of the east rail of the west pair of rails. BENCH MARK STAMPING: 4255 E 1987 DESIGNATION: 846 4255 E MONUMENTATION: Tidal Station disk VM#: 2261 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Concrete stairway OPUS PID: LATITUDE: 41° 39.0' N ( 41.65000) LONGITUDE: 72° 37.6' W ( -72.62670) The bench mark is a disk set in the outside end of the lowest step of an outside concrete stairway at 51 Belamose Avenue, 41.24 m (135.3 ft) west of the west rail of a railroad track which intersects Belamose Avenue and passes east of 51 Belamose Avenue, 29.20 m (95.8 ft) along the east wall from the NE corner of 51 Belamose Avenue, and 2.01 m (6.6 ft) north of the SE corner of the easternmost wall of the building.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 8464255 PUBLICATION DATE: 05/16/2003 Name: ROCKY HILL,CONNECTICUT RIVER CT NOAA Chart: 12377 Latitude: 41° 39.8' N ( 41.66330) USGS Quad: HARTFORD SOUTH Longitude: 72° 37.8' W ( -72.63000) T I D A L D A T U M S Tidal datums at ROCKY HILL,CONNECTICUT RIVER based on: LENGTH OF SERIES: 4 MONTHS TIME PERIOD: June 1987 - September 1987 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 8461490 NEW LONDON, THAMES RIVER Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 0.689 MEAN HIGH WATER MHW = 0.611 MEAN SEA LEVEL MSL = 0.335 MEAN TIDE LEVEL MTL = 0.325 MEAN LOW WATER MLW = 0.038 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 1 1938 7.217 6.606 2 1938 13.544 12.933 3 1938 14.247 13.636 4255 D 1987 11.093 10.482 4255 E 1987 9.581 8.970
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 8464255 PUBLICATION DATE: 05/16/2003 Name: ROCKY HILL,CONNECTICUT RIVER CT NOAA Chart: 12377 Latitude: 41° 39.8' N ( 41.66330) USGS Quad: HARTFORD SOUTH Longitude: 72° 37.8' W ( -72.63000) 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.