U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 6 Station ID: 8720203 PUBLICATION DATE: 02/05/2004 Name: BLOUNT ISLAND BRIDGE FL NOAA Chart: 11491 Latitude: 30° 24.8' N ( 30.41330) USGS Quad: EASTPORT Longitude: 81° 32.7' W ( -81.54500) To reach the tidal bench marks from the intersection of New Berlin Road and State Road 105 in Jacksonville, proceed 2.3 km (1.4 mi) east on State Road 105 to the residence at 4822 Heckscher Drive on the south side of the road. The bench marks are located along Heckscher Drive. The tide gage and staff were located on a privately owned pier behind the residence. T I D A L B E N C H M A R K S
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 6 Station ID: 8720203 PUBLICATION DATE: 02/05/2004 Name: BLOUNT ISLAND BRIDGE FL NOAA Chart: 11491 Latitude: 30° 24.8' N ( 30.41330) USGS Quad: EASTPORT Longitude: 81° 32.7' W ( -81.54500) T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: P 325 1970 DESIGNATION: P 325 MONUMENTATION: Bench Mark disk VM#: 5084 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: BC0285 SETTING CLASSIFICATION: Concrete base of a tower OPUS PID: LATITUDE: 30° 24.8' N ( 30.41389) LONGITUDE: 81° 32.7' W ( -81.54417) The primary bench mark is a disk set on the top of the SW corner of the SE concrete base of the middle one of three transmission line towers, 1.3 km (0.8 mi) west of the bridge over Browns Creek, 0.6 km (0.4 mi) NE of the east end of the old wooden bridge over San Carlos Creek, which is now a fishing bridge on Heckscher Drive, 64.92 m (213.0 ft) north of the centerline of Heckscher Drive, 0.30 m (1.0 ft) NW of a carsonite witness post, and 1.07 m (3.5 ft) above the ground. Note: The mark has been defaced, use with caution. BENCH MARK STAMPING: 0203 A 1982 DESIGNATION: 872 0203 A TIDAL MONUMENTATION: Tidal Station disk VM#: 5085 AGENCY: National Ocean Survey (NOS) IDB PID#: BC2482 SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 30° 24.7' N ( 30.41222) LONGITUDE: 81° 32.7' W ( -81.54556) The bench mark is a disk set in a concrete monument, 0.2 km (0.1 mi) east of the San Carlos Creek Bridge, 17.10 m (56.1 ft) SE of the centerline of Heckscher Drive, 3.44 m (11.3 ft) WSW of the north fence corner of Jacksonville City property, 3.38 m (11.1 ft) SW of a utility pole, 1 m (3 ft) NNW of a fence line, and 0.76 m (2.5 ft) NNW of a carsonite witness post.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 6 Station ID: 8720203 PUBLICATION DATE: 02/05/2004 Name: BLOUNT ISLAND BRIDGE FL NOAA Chart: 11491 Latitude: 30° 24.8' N ( 30.41330) USGS Quad: EASTPORT Longitude: 81° 32.7' W ( -81.54500) T I D A L B E N C H M A R K S BENCH MARK STAMPING: L 325 DESIGNATION: L 325 MONUMENTATION: Survey disk VM#: 5086 AGENCY: Florida Department of Transportation (FLDOT) IDB PID#: BC0283 SETTING CLASSIFICATION: Concrete walkway OPUS PID: LATITUDE: 30° 24.7' N ( 30.41170) LONGITUDE: 81° 33.0' W ( -81.55000) The bench mark is a disk set on top of the south concrete walkway of the highway bridge over San Carlos Creek, 5.55 m (18.2 ft) south of the centerline of the highway, 0.49 m (1.6 ft) east of the west end of the walkway, and 0.3 m (1 ft) above highway level.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 6 Station ID: 8720203 PUBLICATION DATE: 02/05/2004 Name: BLOUNT ISLAND BRIDGE FL NOAA Chart: 11491 Latitude: 30° 24.8' N ( 30.41330) USGS Quad: EASTPORT Longitude: 81° 32.7' W ( -81.54500) T I D A L B E N C H M A R K S BENCH MARK STAMPING: M 325 DESIGNATION: M 325 MONUMENTATION: Survey disk VM#: 5087 AGENCY: Florida Department of Transportation (FLDOT) IDB PID#: BC0284 SETTING CLASSIFICATION: Concrete walkway OPUS PID: LATITUDE: 30° 24.7' N ( 30.41170) LONGITUDE: 81° 32.8' W ( -81.54670) The bench mark is a disk set on the north concrete walkway of the highway bridge over San Carlos Creek, 5.33 m (17.5 ft) north of the centerline of the highway, 0.46 m (1.5 ft) west of the east end of walkway, and 0.3 m (1 ft) above highway level.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 6 Station ID: 8720203 PUBLICATION DATE: 02/05/2004 Name: BLOUNT ISLAND BRIDGE FL NOAA Chart: 11491 Latitude: 30° 24.8' N ( 30.41330) USGS Quad: EASTPORT Longitude: 81° 32.7' W ( -81.54500) T I D A L D A T U M S Tidal datums at BLOUNT ISLAND BRIDGE based on: LENGTH OF SERIES: 3 MONTHS TIME PERIOD: September 1977 - November 1977 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 8720220 MAYPORT Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 1.145 MEAN HIGH WATER MHW = 1.086 North American Vertical Datum NAVD88 = 0.697 MEAN SEA LEVEL MSL = 0.593 MEAN TIDE LEVEL MTL = 0.557 MEAN LOW WATER MLW = 0.028 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW P 325 1970 3.852 2.766 0203 A 1982 2.015 0.929 L 325 4.421 3.335 M 325 4.416 3.330
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 6 of 6 Station ID: 8720203 PUBLICATION DATE: 02/05/2004 Name: BLOUNT ISLAND BRIDGE FL NOAA Chart: 11491 Latitude: 30° 24.8' N ( 30.41330) USGS Quad: EASTPORT Longitude: 81° 32.7' W ( -81.54500) 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.