U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 7 Station ID: 8420411 PUBLICATION DATE: 02/18/2005 Name: DOVER, COCHECO RIVER NH NOAA Chart: 13285 Latitude: 43° 11.9' N ( 43.19830) USGS Quad: DOVER EAST Longitude: 70° 52.1' W ( -70.86830) To reach the tidal bench marks from the intersection of Washington Street and Central Avenue (Route 108) in downtown Dover, proceed SE on Washington Street for one block, turn left and continue on Main Street, bear right on Poplar Street, then turn right on Cocheco Street and proceed to George's Marina. The bench marks are along Cocheco Street and Washington Street. The tide gage was located at the dock at George's Marina. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: D 50 RESET 1977 DESIGNATION: D 50 RESET 1977 MONUMENTATION: Bench Mark disk VM#: 13987 AGENCY: National Geodetic Survey (NGS) IDB PID#: OC1094 SETTING CLASSIFICATION: Bridge abutment OPUS PID: LATITUDE: 43° 11.7' N ( 43.19500) LONGITUDE: 70° 52.4' W ( -70.87330) The primary bench mark is a disk set in the south abutment of the east end of the Washington Street bridge over the Cocheco River in downtown Dover, 0.3 km (0.2 mi) east of the Post Office on Washington Street, 9.8 m (32 ft) south of the centerline of the street, 0.9 m (3 ft) south of a guardrail, and 0.3 m (1 ft) west of a brick wall.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 7 Station ID: 8420411 PUBLICATION DATE: 02/18/2005 Name: DOVER, COCHECO RIVER NH NOAA Chart: 13285 Latitude: 43° 11.9' N ( 43.19830) USGS Quad: DOVER EAST Longitude: 70° 52.1' W ( -70.86830) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 0411 A 1998 DESIGNATION: 842 0411 A MONUMENTATION: Tidal Station disk VM#: 13984 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Retaining wall OPUS PID: LATITUDE: 43° 11.9' N ( 43.19830) LONGITUDE: 70° 52.2' W ( -70.87000) The bench mark is a disk set in the east end of the concrete retaining wall along the north side of Cocheco Street near George's Marina, 0.2 km (0.1 mi) east on Cocheco Street from its intersection with Portland Street, 13.65 m (44.8 ft) east of power pole No. 119-14, 4.58 m (15.0 ft) north of the centerline of Cocheco Street, 0.74 m (2.4 ft) west of the east end of the wall, and 1 m (3.3 ft) above ground level. BENCH MARK STAMPING: 0411 B 1998 DESIGNATION: 842 0411 B MONUMENTATION: Tidal Station disk VM#: 13985 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Concrete pad OPUS PID: LATITUDE: 43° 11.9' N ( 43.19830) LONGITUDE: 70° 52.0' W ( -70.86670) The bench mark is a disk set in the SE corner of a concrete pad on the west side of George's Marina Ships Store, 0.08 km (0.05 mi) east on Cocheco Street from its intersection with Portland Street, 24.78 m (81.3 ft) SW of the SE corner of the store, 18.20 m (59.7 ft) NE of power pole No. 119-9-52-2 on the south side of Cocheco Street, and 1.88 m (6.2 ft) SSE of the SW corner of the store.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 7 Station ID: 8420411 PUBLICATION DATE: 02/18/2005 Name: DOVER, COCHECO RIVER NH NOAA Chart: 13285 Latitude: 43° 11.9' N ( 43.19830) USGS Quad: DOVER EAST Longitude: 70° 52.1' W ( -70.86830) T I D A L B E N C H M A R K S BENCH MARK STAMPING: DESIGNATION: 842 0411 P7 MONUMENTATION: Survey disk VM#: 13986 AGENCY: City of Dover IDB PID#: SETTING CLASSIFICATION: Sidewalk OPUS PID: LATITUDE: 43° 11.7' N ( 43.19500) LONGITUDE: 70° 52.4' W ( -70.87330) The bench mark is a disk set in the middle of the sidewalk at the NE corner of the intersection of Washington Street and Central Avenue, in front of the Bank of New Hampshire, 6.35 m (20.8 ft) west of the SE corner of the bank entrance, 5.13 m (16.8 ft) SSW of the NE corner of the entrance, and 1.41 m (4.6 ft) SE of a light pole.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 7 Station ID: 8420411 PUBLICATION DATE: 02/18/2005 Name: DOVER, COCHECO RIVER NH NOAA Chart: 13285 Latitude: 43° 11.9' N ( 43.19830) USGS Quad: DOVER EAST Longitude: 70° 52.1' W ( -70.86830) T I D A L B E N C H M A R K S BENCH MARK STAMPING: F 5 1933 DESIGNATION: F 5 MONUMENTATION: Bench Mark disk VM#: 13988 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: OC0394 SETTING CLASSIFICATION: Large brick building OPUS PID: LATITUDE: 43° 11.7' N ( 43.19500) LONGITUDE: 70° 52.5' W ( -70.87500) The bench mark is a disk set vertically in the north face of the New Hampshire Department of Human Services building (four-storied brick, formerly the Masonic Temple), near the intersection of Washington and Locust Streets, 11 m (36 ft) east of the east curb of Locust Street, 8.81 m (28.9 ft) east of the NW corner of the building, 3.66 m (12.0 ft) south of the south curb of Washington Street, and 1.34 m (4.4 ft) above the sidewalk.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 7 Station ID: 8420411 PUBLICATION DATE: 02/18/2005 Name: DOVER, COCHECO RIVER NH NOAA Chart: 13285 Latitude: 43° 11.9' N ( 43.19830) USGS Quad: DOVER EAST Longitude: 70° 52.1' W ( -70.86830) T I D A L B E N C H M A R K S BENCH MARK STAMPING: Y 1 1923 56.552 DESIGNATION: Y 1 MONUMENTATION: Bench Mark disk VM#: 13989 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: OC0328 SETTING CLASSIFICATION: Large building OPUS PID: LATITUDE: 43° 11.7' N ( 43.19500) LONGITUDE: 70° 52.6' W ( -70.87670) The bench mark is a disk set vertically in the east face of the U.S. Post Office near the intersection of Washington and Walnut Streets, near the SE corner of the stone foundation of the building, 11.89 m (39.0 ft) north of the north curb of Washington Street, 6.70 m (22 ft) west of the west curb of Walnut Street, 0.61 m (2.0 ft) north of the SE corner of the building, 1.52 m (5 ft) above Walnut Street, and 0.46 m (1.5 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 6 of 7 Station ID: 8420411 PUBLICATION DATE: 02/18/2005 Name: DOVER, COCHECO RIVER NH NOAA Chart: 13285 Latitude: 43° 11.9' N ( 43.19830) USGS Quad: DOVER EAST Longitude: 70° 52.1' W ( -70.86830) T I D A L D A T U M S Tidal datums at DOVER, COCHECO RIVER based on: LENGTH OF SERIES: 2 MONTHS TIME PERIOD: July 1998 - August 1998 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 8418150 PORTLAND, CASCO BAY Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 2.335 MEAN HIGH WATER MHW = 2.225 North American Vertical Datum NAVD88 = 1.198 MEAN SEA LEVEL MSL = 1.191 MEAN TIDE LEVEL MTL = 1.152 MEAN LOW WATER MLW = 0.078 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW D 50 RESET 1977 8.085 5.860 0411 A 1998 7.496 5.271 0411 B 1998 5.237 3.012 842 0411 P7 13.098 10.873 F 5 1933 15.990 13.765 Y 1 1923 56.552 18.235 16.010
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 7 of 7 Station ID: 8420411 PUBLICATION DATE: 02/18/2005 Name: DOVER, COCHECO RIVER NH NOAA Chart: 13285 Latitude: 43° 11.9' N ( 43.19830) USGS Quad: DOVER EAST Longitude: 70° 52.1' W ( -70.86830) 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.