U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 8660098 PUBLICATION DATE: 08/03/2004 Name: LITTLE RIVER NECK SC NOAA Chart: 11535 Latitude: 33° 52.2' N ( 33.87000) USGS Quad: LITTLE RIVER Longitude: 78° 34.4' W ( -78.57330) To reach the tidal bench marks from the overpass of State Road 90 over U.S. Highway 17 at Little River, proceed SW on State Road 90 for 0.2 km (0.1 mi), then turn left onto Sea Mountain Highway and proceed SE following the signs for Cherry Grove for 0.2 km (0.1 mi) to the first intersection after the bridge, then turn left and proceed east and NE on Little River Neck Road (S-26-236) for 6.3 km (3.9 mi), following the signs for Little River Neck, passing underneath the overpass of U.S. Highway 17 over the Intracoastal Waterway, to the entrance gate of Tilghman Point. Check with the caretaker at the first house on the left. From the front gate proceed east along the dirt road for 2.4 km (1.5 mi), turn left onto the first dirt road on the left past the summerhouse driveway. The bench marks are along the dirt road and in the vicinity of a fresh water pond. The tide gage and staff were on a piling in Little River across the channel from daymarker #2. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: IW NO 1 1975 DESIGNATION: 866 0098 TIDAL IW 1 MONUMENTATION: Tidal Station disk VM#: 3664 AGENCY: National Ocean Survey (NOS) IDB PID#: DD1747 SETTING CLASSIFICATION: Copper clad steel rod OPUS PID: LATITUDE: 33° 52.2' N ( 33.87000) LONGITUDE: 78° 34.6' W ( -78.57670) The bench mark is a disk located between the fresh water pond and the dirt road surrounding the pond, 15.85 m (52.0 ft) WSW of a multi-trunk tree on the east side of the dirt road, 13 m (43 ft) SE of the NE end of the pond, 12.19 m (40.0 ft) SSW of the centerline of the dirt road at the beginning of the curve at the NE end of the pond, 9 m (30 ft) north of the north face of a 0.46 m (1.5 ft) diameter leaning pine tree on the NW side of a fire trail, 8.08 m (26.5 ft) west of the intersection of the dirt road and the fire trail, and 6.16 m (20.2 ft) SSW of a 0.37 m (1.2 ft) diameter pine tree on the SW side of the dirt road. The bench mark is set 0.15 m (0.5 ft) below the ground, crimped to the top of a copper-clad steel rod driven an unspecified depth and encased in a 5-inch PVC pipe and concrete kickblock.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 Station ID: 8660098 PUBLICATION DATE: 08/03/2004 Name: LITTLE RIVER NECK SC NOAA Chart: 11535 Latitude: 33° 52.2' N ( 33.87000) USGS Quad: LITTLE RIVER Longitude: 78° 34.4' W ( -78.57330) T I D A L B E N C H M A R K S BENCH MARK STAMPING: IW NO 2 1975 DESIGNATION: 866 0098 TIDAL IW 2 MONUMENTATION: Tidal Station disk VM#: 3665 AGENCY: National Ocean Survey (NOS) IDB PID#: DD1746 SETTING CLASSIFICATION: Copper clad steel rod OPUS PID: LATITUDE: 33° 52.2' N ( 33.87000) LONGITUDE: 78° 34.7' W ( -78.57830) The bench mark is a disk located between the fresh water pond and the road surrounding the pond, 7 m (22 ft) NW of the NW end of the pond, and 3.35 m (11.0 ft) SE of the centerline of the dirt road. The bench mark is set 3 cm (0.1 ft) below the ground, crimped to the top of a copper-clad steel rod driven to an unspecified depth to refusal and encased in a PVC pipe and concrete kickblock. BENCH MARK STAMPING: IW NO 3 1975 DESIGNATION: 866 0098 TIDAL IW 3 MONUMENTATION: Tidal Station disk VM#: 3666 AGENCY: National Ocean Survey (NOS) IDB PID#: DD1744 SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 33° 52.1' N ( 33.86830) LONGITUDE: 78° 34.8' W ( -78.58000) The bench mark is a disk set in the top of a concrete monument south of the fresh water pond, 152 m (498 ft) south of bench mark IW NO 4 1975, 35.60 m (116.8 ft) WSW of the northernmost unnumbered pole (first of five poles north to south), 21 m (70 ft) NW of a 0.55 m (1.8 ft) diameter pecan tree, 16.61 m (54.5 ft) SE of a 0.46 m (1.5 ft) diameter pecan tree, and 16 m (54 ft) SW of a 0.70 m (2.3 ft) diameter pecan tree across the road.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 8660098 PUBLICATION DATE: 08/03/2004 Name: LITTLE RIVER NECK SC NOAA Chart: 11535 Latitude: 33° 52.2' N ( 33.87000) USGS Quad: LITTLE RIVER Longitude: 78° 34.4' W ( -78.57330) T I D A L B E N C H M A R K S BENCH MARK STAMPING: IW NO 4 1975 DESIGNATION: 866 0098 TIDAL IW 4 MONUMENTATION: Tidal Station disk VM#: 3667 AGENCY: National Ocean Survey (NOS) IDB PID#: DD1745 SETTING CLASSIFICATION: Copper clad steel rod OPUS PID: LATITUDE: 33° 52.2' N ( 33.87000) LONGITUDE: 78° 34.8' W ( -78.58000) The bench mark is a disk located at the intersection of the dirt road and the road surrounding the pond, 320 m (1050 ft) SW of bench mark IW NO 2 1975, 13 m (42 ft) NE of the centerline of the dirt road, 13 m (42 ft) NW of the centerline of the pond road, and 4 m (13 ft) east of a 0.3 m (1 ft) diameter pecan tree. The bench mark is set 9 cm (0.3 ft) below the ground, crimped to the top of a copper-clad steel rod driven to an unspecified depth to refusal, and encased in a PVC pipe and concrete kickblock. BENCH MARK STAMPING: IW NO 5 1975 DESIGNATION: 866 0098 TIDAL IW 5 MONUMENTATION: Tidal Station disk VM#: 3668 AGENCY: National Ocean Survey (NOS) IDB PID#: DD1748 SETTING CLASSIFICATION: Concrete monument OPUS PID: LATITUDE: 33° 52.1' N ( 33.86830) LONGITUDE: 78° 34.8' W ( -78.58000) The bench mark is a disk set in the top of a concrete monument in a small clearing on the west side of the road, 0.2 km (0.1 mi) SSE of bench mark IW NO 1 1975, 1622 m (530 ft) SE of the pond, 5 m (17 ft) west of the centerline of the dirt road, 1.01 m (3.3 ft) SW of a wooden witness post, and level with the ground.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 8660098 PUBLICATION DATE: 08/03/2004 Name: LITTLE RIVER NECK SC NOAA Chart: 11535 Latitude: 33° 52.2' N ( 33.87000) USGS Quad: LITTLE RIVER Longitude: 78° 34.4' W ( -78.57330) T I D A L D A T U M S Tidal datums at LITTLE RIVER NECK based on: LENGTH OF SERIES: 9 MONTHS TIME PERIOD: May 1975 - January 1976 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: MEAN HIGHER HIGH WATER MHHW = 1.577 MEAN HIGH WATER MHW = 1.460 North American Vertical Datum NAVD88 = 0.863 MEAN SEA LEVEL MSL = 0.760 MEAN TIDE LEVEL MTL = 0.754 MEAN LOW WATER MLW = 0.049 MEAN LOWER LOW WATER MLLW = 0.000 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW IW NO 1 1975 4.260 2.800 IW NO 2 1975 4.959 3.499 IW NO 3 1975 8.153 6.693 IW NO 4 1975 8.031 6.571 IW NO 5 1975 6.485 5.025
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 8660098 PUBLICATION DATE: 08/03/2004 Name: LITTLE RIVER NECK SC NOAA Chart: 11535 Latitude: 33° 52.2' N ( 33.87000) USGS Quad: LITTLE RIVER Longitude: 78° 34.4' W ( -78.57330) 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.