U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 4 PUBLICATION DATE: 09/19/1988 Station ID: 8662299 SUPERCEDED DATE: 04/21/2003 Name: CLAMBANK CREEK SOUTH CAROLINA NOAA Chart: 11532 Latitude: 33° 20.0' N USGS Quad: NORTH ISLAND Longitude: 79° 11.6' W To reach the tidal bench marks from the east end of U.S. Highway 17 bridge over Waccamaw River, proceed east on U.S. Highway 17 for 1.2 miles (1.9 km) to the entrance to Hobcaw Barony, then south on the entrance road for about 80 feet (24 m) to an electric gate and telephone (dial 11 to obtain permission to enter), continue south along a gravel road for 0.35 mile (0.56 km) to a three way junction, then easterly for 0.4 mile (0.6 km) to a Y-junction, then SE for 1.8 miles (2.9 km) to the entrance to a marine laboratory, continue south for 1.1 miles (1.8 km) to a T-junction and 1.9 miles (3.1 km) southerly and northerly to a lookout tower and a cinder block building on Goat Island. The bench marks are at the boat landing ramp and dock and at the lookout tower. The tide gage and staff were on the inside of the right angle dock. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 2299 D 1976 MONUMENTATION: Survey Disk VM#: 3924 AGENCY: PID#: DD1355 SETTING CLASSIFICATION: Copper-clad Steel Rod The bench mark is along the dirt road between the dock and the lookout tower, about 300 feet (91 m) NW of Bench Mark NO 2 1968, 144.5 feet (44.0 m) east of the east leg of the lookout tower, 21.5 feet (6.6 m) SSE of a large cedar tree, 10.6 feet (3.2 m) NE of the centerline of the dirt road leading to the boat landing ramp, and 3.0 feet (0.9 m) SW of a steel witness post with sign. The bench mark is 0.2 foot (0.1 m) above ground level, crimped to a copper- clad steel rod driven 56 feet (17 m) to refusal, and encased in a 4-inch PVC pipe and concrete kickblock. BENCH MARK STAMPING: 2299 E 1976 MONUMENTATION: Survey Disk VM#: 3925 AGENCY: PID#: DD1354 SETTING CLASSIFICATION: Concrete Footing The bench mark is set in the east leg of the lookout tower, 144.5 feet (44.0 m) SW of Bench Mark 2299 D 1976, 57.0 feet (17.4 m) south of the south corner of a cinder block building, 6.0 feet (1.8 m) NNW of a cedar tree, 1.1 feet (0.3 m) SSE of a metal witness post with sign, and 0.7 foot (0.2 m) above ground level.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 4 PUBLICATION DATE: 09/19/1988 Station ID: 8662299 SUPERCEDED DATE: 04/21/2003 Name: CLAMBANK CREEK SOUTH CAROLINA NOAA Chart: 11532 Latitude: 33° 20.0' N USGS Quad: NORTH ISLAND Longitude: 79° 11.6' W T I D A L B E N C H M A R K S BENCH MARK STAMPING: 2299 F 1976 MONUMENTATION: Survey Disk VM#: 3926 AGENCY: PID#: DD1353 SETTING CLASSIFICATION: Copper-clad Steel Rod The bench mark is near a 3-foot (1 m) diameter lone oak tree WSW of the lookout tower, 94.3 feet (28.7 m) south of the west corner of a cinder block building, 25.2 feet (7.7 m) west of the south leg of the lookout tower, 9.8 feet (3.0 m) NNW of the lone oak tree, 9.2 feet (2.8 m) SE of the centerline of the dirt road leading to the cinder block building, and 4.2 feet (1.3 m) NE of a witness sign nailed to a tree. The bench mark is crimped to a copper- clad steel rod driven to an unspecified depth to refusal, and encased in a 4-inch PVC pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 4 PUBLICATION DATE: 09/19/1988 Station ID: 8662299 SUPERCEDED DATE: 04/21/2003 Name: CLAMBANK CREEK SOUTH CAROLINA NOAA Chart: 11532 Latitude: 33° 20.0' N USGS Quad: NORTH ISLAND Longitude: 79° 11.6' W T I D A L D A T U M S Tidal datums at CLAMBANK CREEK based on: LENGTH OF SERIES: 12 MONTHS TIME PERIOD: MAY 1976 - APRIL 1977 TIDAL EPOCH: 1960-1978 CONTROL TIDE STATION: 8665530 CHARLESTON Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET: HIGHEST OBSERVED WATER LEVEL (06/01/1977) = 7.11 MEAN HIGHER HIGH WATER MHHW = 5.27 MEAN HIGH WATER MHW = 4.94 MEAN TIDE LEVEL MTL = 2.57 MEAN LOW WATER MLW = 0.21 MEAN LOWER LOW WATER MLLW = 0.00 LOWEST OBSERVED WATER LEVEL (12/21/1976) = -2.27 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In FEET above: Stamping or Designation MLLW MHW 2299 D 1976 7.74 2.80 2299 E 1976 8.76 3.82 2299 F 1976 7.91 2.97
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 4 PUBLICATION DATE: 09/19/1988 Station ID: 8662299 SUPERCEDED DATE: 04/21/2003 Name: CLAMBANK CREEK SOUTH CAROLINA NOAA Chart: 11532 Latitude: 33° 20.0' N USGS Quad: NORTH ISLAND Longitude: 79° 11.6' W 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 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.