U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 7 Station ID: 8720832 PUBLICATION DATE: 11/01/2011 Name: WELAKA, ST. JOHNS RIVER FL NOAA Chart: 11495 Latitude: 29° 28.6' N ( 29.47670) USGS Quad: WELAKA Longitude: 81° 40.5' W ( -81.67500) To reach the tidal bench marks from the intersection of State Road 308B (Oak Street) and State Road 309 in Welaka, proceed west on State Road 308B for 0.24 km (0.15 mi) to Front Street, then south on Front Street for 0.5 km (0.3 mi) to the dirt road leading west to the Greene residence, the house just to the north of Trail Boss Campgrounds. The bench marks are along Front and Elm Streets. The tide gage and staff were on the west end of the northernmost finger dock behind the Greene residence. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 0832 C 1995 DESIGNATION: 872 0832 C MONUMENTATION: Flange-encased Rod VM#: 16183 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Stainless steel rod OPUS PID: LATITUDE: 29° 28.6' N ( 29.47670) LONGITUDE: 81° 40.5' W ( -81.67500) The primary bench mark is a flange-encased rod set near the intersection of Front and Palmetto Streets, 54.86 m (180.0 ft) west of the intersection, 18.20 m (59.7 ft) south of the SW corner of the Palms Restaurant, 12.10 m (39.7 ft) north of the center of Palmetto Street, 0.82 m (2.7 ft) south of a carsonite witness post, and about 2 m (6 ft) above the level of Palmetto Street. The datum point is the top of a stainless steel rod driven 17.7 m (58 ft) to refusal, and encased in a PVC pipe and NOS logo cap.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 7 Station ID: 8720832 PUBLICATION DATE: 11/01/2011 Name: WELAKA, ST. JOHNS RIVER FL NOAA Chart: 11495 Latitude: 29° 28.6' N ( 29.47670) USGS Quad: WELAKA Longitude: 81° 40.5' W ( -81.67500) T I D A L B E N C H M A R K S BENCH MARK STAMPING: N 19 1933 22.903 DESIGNATION: N 19 MONUMENTATION: Bench Mark disk VM#: 5256 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: AQ0678 SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 29° 28.7' N ( 29.47830) LONGITUDE: 81° 40.5' W ( -81.67500) The bench mark is a disk set in the top of a concrete monument at the intersection of Front and Elm Streets, across from Welaka Civic Hall, 9 m (30 ft) north of the centerline of Elm Street, 9 m (29 ft) east of the centerline of Front Street, 1 m (2 ft) east of a flagpole at the SW corner of a concrete block building, and 3 cm (0.1 ft) above ground level. BENCH MARK STAMPING: NO 1 1934 DESIGNATION: 872 0832 TIDAL 1 MONUMENTATION: Bench Mark disk VM#: 5257 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: AQ2571 SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 29° 28.8' N ( 29.48000) LONGITUDE: 81° 40.4' W ( -81.67330) The bench mark is a disk set in a concrete monument at the intersection of Front and Palmetto Streets, 12.56 m (41.2 ft) east of the centerline of Front Street, 5.67 m (18.6 ft) north of the centerline of Palmetto Street, 0.15 m (0.5 ft) NW of power pole #3-3724-1203-0-6, and 9 cm (0.3 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 7 Station ID: 8720832 PUBLICATION DATE: 11/01/2011 Name: WELAKA, ST. JOHNS RIVER FL NOAA Chart: 11495 Latitude: 29° 28.6' N ( 29.47670) USGS Quad: WELAKA Longitude: 81° 40.5' W ( -81.67500) T I D A L B E N C H M A R K S BENCH MARK STAMPING: WELAKA 1935 DESIGNATION: WELAKA MONUMENTATION: Triangulation Station disk VM#: 5258 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: AQ1775 SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 29° 28.6' N ( 29.47670) LONGITUDE: 81° 40.4' W ( -81.67330) The bench mark is a disk set in a square concrete monument in an open area near the river, 81 m (265 ft) south of the post office, 46 m (150 ft) east of the river, 40 m (132 ft) west of the centerline of a paved street, 15 m (49 ft) SSE of the SW corner of an old garage, 4 m (14 ft) north of a yard fence, 0.30 m (1.0 ft) east of a metal witness post, and 6 cm (0.2 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 7 Station ID: 8720832 PUBLICATION DATE: 11/01/2011 Name: WELAKA, ST. JOHNS RIVER FL NOAA Chart: 11495 Latitude: 29° 28.6' N ( 29.47670) USGS Quad: WELAKA Longitude: 81° 40.5' W ( -81.67500) T I D A L B E N C H M A R K S BENCH MARK STAMPING: WELAKA 1935 NO 4 1968 DESIGNATION: WELAKA RM 4 MONUMENTATION: Reference Mark disk VM#: 5259 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: AQ1774 SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 29° 28.6' N ( 29.47670) LONGITUDE: 81° 40.4' W ( -81.67330) The bench mark is a disk set in a concrete monument in the SE corner of an open area, 46 m (150 ft) east of the river, 9 m (30 ft) west of the centerline of a paved street, 0.67 m (2.2 ft) north of the fence corner with a 3 x 3-inch square concrete property corner stake, and at ground level.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 7 Station ID: 8720832 PUBLICATION DATE: 11/01/2011 Name: WELAKA, ST. JOHNS RIVER FL NOAA Chart: 11495 Latitude: 29° 28.6' N ( 29.47670) USGS Quad: WELAKA Longitude: 81° 40.5' W ( -81.67500) T I D A L B E N C H M A R K S BENCH MARK STAMPING: WELAKA 1935 NO 3 1968 DESIGNATION: WELAKA RM 3 MONUMENTATION: Reference Mark disk VM#: 16182 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: AQ1776 SETTING CLASSIFICATION: Concrete ramp OPUS PID: LATITUDE: 29° 28.7' N ( 29.47830) LONGITUDE: 81° 40.5' W ( -81.67500) The bench mark is a disk set in a concrete foundation near the intersection of Front and Oak streets, 32.0 m (105.0 ft) west of the centerline of Front Street, 18.3 cm (0.6 ft) south of the west edge of a door to a garage, and 0.3 m (1.0 ft) south of a carsonite witness post.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 6 of 7 Station ID: 8720832 PUBLICATION DATE: 11/01/2011 Name: WELAKA, ST. JOHNS RIVER FL NOAA Chart: 11495 Latitude: 29° 28.6' N ( 29.47670) USGS Quad: WELAKA Longitude: 81° 40.5' W ( -81.67500) T I D A L D A T U M S Tidal datums at WELAKA, ST. JOHNS RIVER based on: LENGTH OF SERIES: 6 MONTHS TIME PERIOD: October 2003 - March 2004 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 8720503 RED BAY POINT, ST JOHNS RIVER Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: MEAN HIGHER HIGH WATER MHHW = 0.148 MEAN HIGH WATER MHW = 0.143 MEAN TIDE LEVEL MTL = 0.078 MEAN SEA LEVEL MSL = 0.076 MEAN LOW WATER MLW = 0.013 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum NAVD88 = -0.006 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 0832 C 1995 4.196 4.053 N 19 1933 22.903 6.692 6.549 NO 1 1934 6.783 6.640 WELAKA 1935 6.667 6.524 WELAKA 1935 NO 4 1968 6.976 6.833 WELAKA 1935 NO 3 1968 6.594 6.451 Foot Notes:
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 7 of 7 Station ID: 8720832 PUBLICATION DATE: 11/01/2011 Name: WELAKA, ST. JOHNS RIVER FL NOAA Chart: 11495 Latitude: 29° 28.6' N ( 29.47670) USGS Quad: WELAKA Longitude: 81° 40.5' W ( -81.67500) 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.