U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 4 Station ID: 9466298 PUBLICATION DATE: 01/14/2011 Name: NELSON IS (BLUFF S.E. OF TUNUNAK) AK NOAA Chart: 16006 Latitude: 60° 31.0' N ( 60.51670) USGS Quad: NUNIVAK ISLAND C-1 Longitude: 165° 8.0' W (-165.13300) To reach the bench marks from the Toksook Bay runway, proceed 0.4 mi (0.6 km) NW on Airport Road to where the road curves to the left, continue 0.7 mi (1.1 km) WSW on Airport Road to where the road turns left, continue 0.8 mi (1.3 km) SSE on Airport Road along the west side of the fuel tank farm to the beach in front of the village of Toksook Bay. Continue by skiff 1.5 mi (2.4 km) WSW following the shoreline to the second prominent rock point, with 12 m (40 ft) high overhanging cliffs. The bench marks are on top of the bluff, between the seaward point and the first small stream 0.1 mi (0.2 km) to the east. The tide gauges were housed on top of the point and the orifices were offshore of the point. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 6298 C 2010 DESIGNATION: 946 6298 C MONUMENTATION: Metal Rod VM#: 19707 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID#: BBBZ36 LATITUDE: 60° 31.1' N ( 60.51858) LONGITUDE: 165° 8.5' W (-165.14233) The primary bench mark is a disk set in the tundra 77.49 m (254.2 ft) NNE of bench mark 946 6298 B, 66.0 m (217 ft) west of a small stream where it flows SE over the bluff to the beach below, 58.0 m (190 ft) west of the 7 m (23 ft) high bluff, and 17.1 m (56 ft) NW of the centerline of a dirt track all terrain vehicle trail. The datum point is set 7 cm (0.2 ft) below grade, being the top of a stainless steel rod driven 3.7 m (12.3 ft) to refusal, in a sleeve extending to a depth of 0.9 m (3 ft), and encased in a 6-inch PVC pipe with 7-inch diameter National Geodetic Survey logo cap.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 4 Station ID: 9466298 PUBLICATION DATE: 01/14/2011 Name: NELSON IS (BLUFF S.E. OF TUNUNAK) AK NOAA Chart: 16006 Latitude: 60° 31.0' N ( 60.51670) USGS Quad: NUNIVAK ISLAND C-1 Longitude: 165° 8.0' W (-165.13300) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 6298 B 2010 DESIGNATION: 946 6298 B MONUMENTATION: Metal Rod VM#: 19708 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID: LATITUDE: 60° 31.1' N ( 60.51794) LONGITUDE: 165° 8.6' W (-165.14264) The bench mark is set in the tundra 77.50 m (254.3 ft) north of bench mark 946 6298 A, 77.49 m (254.2 ft) SSW of bench mark 946 6298 C, and 56.0 m (184 ft) west of the bluff. The datum point is set 11 cm (0.4 ft) below grade, being the top of a stainless steel rod driven 3.0 m (9.8 ft) to refusal, in a sleeve extending to a depth of 0.9 m (3 ft), and encased in a 6-inch PVC pipe with 7-inch diameter National Ocean Service logo cap. BENCH MARK STAMPING: 6298 A 2010 DESIGNATION: 946 6298 A MONUMENTATION: Metal Rod VM#: 19709 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Stainless steel rod in sleeve OPUS PID: LATITUDE: 60° 31.0' N ( 60.51725) LONGITUDE: 165° 8.5' W (-165.14233) The bench mark is set in the tundra 77.50 m (254.3 ft) south of bench mark 946 6298 B, 77.30 m (253.6 ft) NW of bench mark 946 6298 TIDAL 2, 65.16 m (213.8 ft) NW of bench mark 946 6298 TIDAL 4, and 51 m (167 ft) west of the bluff. The datum point is set 14 cm (0.5 ft) below grade, being the top of a stainless steel rod driven 1.7 m (5.7 ft) to refusal, in a sleeve extending to a depth of 0.9 m (3 ft), and encased in a 6-inch PVC pipe with 7-inch diameter National Ocean Service logo cap.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 4 Station ID: 9466298 PUBLICATION DATE: 01/14/2011 Name: NELSON IS (BLUFF S.E. OF TUNUNAK) AK NOAA Chart: 16006 Latitude: 60° 31.0' N ( 60.51670) USGS Quad: NUNIVAK ISLAND C-1 Longitude: 165° 8.0' W (-165.13300) T I D A L D A T U M S Tidal datums at NELSON IS (BLUFF S.E. OF TUNUNAK) based on: LENGTH OF SERIES: 3 MONTHS TIME PERIOD: July 2010 - September 2010 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 2.805 MEAN HIGH WATER MHW = 2.682 MEAN SEA LEVEL MSL = 1.503 MEAN TIDE LEVEL MTL = 1.500 MEAN LOW WATER MLW = 0.317 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 6298 C 2010 11.730 9.048 6298 B 2010 13.872 11.190 6298 A 2010 14.862 12.180
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 4 Station ID: 9466298 PUBLICATION DATE: 01/14/2011 Name: NELSON IS (BLUFF S.E. OF TUNUNAK) AK NOAA Chart: 16006 Latitude: 60° 31.0' N ( 60.51670) USGS Quad: NUNIVAK ISLAND C-1 Longitude: 165° 8.0' W (-165.13300) 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.