U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 8665641 PUBLICATION DATE: 08/14/2003 Name: WELCHES WHARF, STONO RIVER SC NOAA Chart: 11524 Latitude: 32° 45.8' N ( 32.76330) USGS Quad: STONO RIVER Longitude: 80° 0.1' W ( -80.00170) To reach the tidal bench marks from the intersection of State Highways 700 (Maybank Highway) and 171 (Folly Road) on James Island, proceed west on State Highway 700 for 2.4 km (1.5 mi) to Riverland Drive, then turn right and proceed north on Riverland Drive for 0.8 km (0.5 mi) to Stono Drive, then turn left and proceed west on Stono Drive for 0.2 km (0.1 mi) to the Welchs property at 151 Stono Drive. The bench marks are near the riverbank behind two homes along Stono Drive. The tide gage and staff were located on the dock behind the Welchs residence. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: NO 2 1933 DESIGNATION: 866 5641 TIDAL 2 MONUMENTATION: Tidal Station disk VM#: 4215 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: CK2273 SETTING CLASSIFICATION: Concrete-filled tile pipe OPUS PID: LATITUDE: 32° 45.8' N ( 32.76330) LONGITUDE: 80° 0.1' W ( -80.00170) The primary bench mark is a disk set flush in a concrete-filled tile pipe behind the residence at 151 Stono Drive, below a sloping embankment near a brick seawall, 7.53 m (24.7 ft) SSW of a stone fence property line, 3.20 m (10.5 ft) ESE of the seawall, 3.17 m (10.4 ft) ENE of a wooden walkway to the dock, 2.77 m (9.1 ft) NNE of steps leading down the embankment, and at ground level.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 Station ID: 8665641 PUBLICATION DATE: 08/14/2003 Name: WELCHES WHARF, STONO RIVER SC NOAA Chart: 11524 Latitude: 32° 45.8' N ( 32.76330) USGS Quad: STONO RIVER Longitude: 80° 0.1' W ( -80.00170) T I D A L B E N C H M A R K S BENCH MARK STAMPING: NO 3 1933 DESIGNATION: 866 5641 TIDAL 3 MONUMENTATION: Tidal Station disk VM#: 4216 AGENCY: US Coast and Geodetic Survey (USC&GS) IDB PID#: CK2272 SETTING CLASSIFICATION: Concrete-filled tile pipe OPUS PID: LATITUDE: 32° 45.8' N ( 32.76330) LONGITUDE: 80° 0.1' W ( -80.00170) The bench mark is a disk set flush in a concrete-filled tile pipe behind the residence at 151 Stono Drive, 12.77 m (41.9 ft) ESE of the brick seawall, 12.22 m (40.1 ft) NW of a large oak tree, 12.04 m (39.5 ft) NE of Bench Mark NO 2 1933, 0.70 m (2.3 ft) SSW of a woven wire fence line, and 0.15 m (0.5 ft) above ground level. BENCH MARK STAMPING: NO 5 1974 DESIGNATION: 866 5641 TIDAL 5 MONUMENTATION: Tidal Station disk VM#: 4217 AGENCY: National Ocean Survey (NOS) IDB PID#: CK2270 SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 32° 45.8' N ( 32.76330) LONGITUDE: 80° 0.1' W ( -80.00170) The bench mark is a disk set flush in a concrete monument in the NW corner of the property at 309 Stono Drive (Gibbs residence),16.98 m (55.7 ft) NNW of the NW corner of the residence, 9.24 m (30.3 ft) NNE of a nautical lamp post at the top of steps leading to the dock, 5.73 m (18.8 ft) ESE of a large twin-trunk oak tree, and at ground level.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 8665641 PUBLICATION DATE: 08/14/2003 Name: WELCHES WHARF, STONO RIVER SC NOAA Chart: 11524 Latitude: 32° 45.8' N ( 32.76330) USGS Quad: STONO RIVER Longitude: 80° 0.1' W ( -80.00170) T I D A L B E N C H M A R K S BENCH MARK STAMPING: NO 6 1974 DESIGNATION: 866 5641 TIDAL 6 MONUMENTATION: Tidal Station disk VM#: 4218 AGENCY: National Ocean Survey (NOS) IDB PID#: CK2269 SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 32° 45.8' N ( 32.76330) LONGITUDE: 80° 0.1' W ( -80.00170) The bench mark is a disk set flush in a concrete monument in the SW corner of the property at 309 Stono Drive (Gibbs residence), 8.02 m (26.3 ft) WSW of the SW corner of a glass-enclosed porch, 7.74 m (25.4 ft) south of the middle of three oak trees near the end of the embankment, 2.38 m (7.8 ft) east of a lone oak tree at the end of the embankment, and at ground level. BENCH MARK STAMPING: NO 4 1974 DESIGNATION: 866 5641 TIDAL 4 MONUMENTATION: Tidal Station disk VM#: 17119 AGENCY: National Ocean Survey (NOS) IDB PID#: CK2271 SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 32° 45.8' N ( 32.76330) LONGITUDE: 80° 0.1' W ( -80.00170) The bench mark is a disk set in a concrete monument near the river bank in the back yard of the residence of 309 Stono Drive, 52.61 m (172.6 ft) WNW of the approximate center of Stono Drive, 30.45 m (99.9 ft) north of the SW corner of the House No. 309, 19.32 m (63.4 ft) NNWof the NW corner of the House No. 309, and 3.54 m (11.6 ft) west of bench mark NO 5 1974.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 8665641 PUBLICATION DATE: 08/14/2003 Name: WELCHES WHARF, STONO RIVER SC NOAA Chart: 11524 Latitude: 32° 45.8' N ( 32.76330) USGS Quad: STONO RIVER Longitude: 80° 0.1' W ( -80.00170) T I D A L D A T U M S Tidal datums at WELCHES WHARF, STONO RIVER based on: LENGTH OF SERIES: 12 MONTHS TIME PERIOD: October 1974 - September 1975 TIDAL EPOCH: 1983-2001 CONTROL TIDE STATION: 8665530 CHARLESTON, COOPER RIVER ENTRANCE Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: HIGHEST OBSERVED WATER LEVEL (07/21/1974) = 2.202 MEAN HIGHER HIGH WATER MHHW = 1.733 MEAN HIGH WATER MHW = 1.635 North American Vertical Datum NAVD88 = 0.957 MEAN SEA LEVEL MSL = 0.938 MEAN TIDE LEVEL MTL = 0.851 MEAN LOW WATER MLW = 0.067 MEAN LOWER LOW WATER MLLW = 0.000 LOWEST OBSERVED WATER LEVEL (02/26/1975) = -0.615 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW NO 2 1933 2.750 1.115 NO 3 1933 4.940 3.305 NO 5 1974 6.477 4.842 NO 6 1974 6.400 4.765 NO 4 1974 6.212 4.577
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 8665641 PUBLICATION DATE: 08/14/2003 Name: WELCHES WHARF, STONO RIVER SC NOAA Chart: 11524 Latitude: 32° 45.8' N ( 32.76330) USGS Quad: STONO RIVER Longitude: 80° 0.1' W ( -80.00170) 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.