U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 8661419 PUBLICATION DATE: 02/13/2004 Name: GARDEN CITY BRRIDGE, MURRELLS INLET SC NOAA Chart: 11535 Latitude: 33° 34.7' N ( 33.57830) USGS Quad: BROOKGREEN Longitude: 79° 0.2' W ( -79.00330) To reach the tidal bench marks from the intersection of U.S. Highway 17 South and Atlantic Avenue, proceed SE on Atlantic Avenue for 1.0 km (0.6 mi), towards Garden City Beach and the bridge over Main Creek. The bench marks are along the road NW of the bridge. The tide gage and staff were on the SW side of the bridge near the NW end. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: GCB NO 1 1975 DESIGNATION: 866 1419 TIDAL GCB 1 MONUMENTATION: Tidal Station disk VM#: 3766 AGENCY: National Ocean Survey (NOS) IDB PID#: DD1494 SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID: LATITUDE: 33° 34.8' N ( 33.58000) LONGITUDE: 79° 0.2' W ( -79.00330) The primary bench mark is a disk located about 91 m (300 ft) NW of the NW end of the bridge over Main Creek, 9.60 m (31.5 ft) NE of the centerline of the highway, 5.30 m (17.4 ft) SE of the center of the last driveway before reaching the bridge on the NE side of the highway, 1.10 m (3.6 ft) east of utility pole #1C-17-1-D, and 0.82 m (2.7 ft) west of a steel witness post. The bench mark is 0.03 m (0.1 ft) below ground level, crimped to the top of a copper-clad steel rod driven 14.6 m (48 ft) to refusal, 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: 8661419 PUBLICATION DATE: 02/13/2004 Name: GARDEN CITY BRRIDGE, MURRELLS INLET SC NOAA Chart: 11535 Latitude: 33° 34.7' N ( 33.57830) USGS Quad: BROOKGREEN Longitude: 79° 0.2' W ( -79.00330) T I D A L B E N C H M A R K S BENCH MARK STAMPING: GCB NO 2 1975 DESIGNATION: 866 1419 TIDAL GCB 2 MONUMENTATION: Tidal Station disk VM#: 3767 AGENCY: National Ocean Survey (NOS) IDB PID#: DD1493 SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID: LATITUDE: 33° 34.9' N ( 33.58170) LONGITUDE: 79° 0.3' W ( -79.00500) The bench mark is a disk located about 105 m (345 ft) NW of Bench Mark GCB NO 1 1975, 8.20 m (26.9 ft) NE of the centerline of the highway, 2.07 m (6.8 ft) west of a 0.24 m (0.8 ft) diameter pine tree, 1.07 m (3.5 ft) north of utility pole #1C-17-1-C, and 0.70 m (2.3 ft) NE of a steel witness post. The bench mark is 0.03 m (0.1 ft) below ground level, crimped to the top of a copper-clad steel rod driven 14.6 m (48 ft) to refusal, and encased in a 4-inch PVC pipe and concrete kickblock. BENCH MARK STAMPING: GCB NO 3 1975 DESIGNATION: 866 1419 TIDAL GCB 3 MONUMENTATION: Tidal Station disk VM#: 3768 AGENCY: National Ocean Survey (NOS) IDB PID#: DD1492 SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID: LATITUDE: 33° 34.9' N ( 33.58170) LONGITUDE: 79° 0.4' W ( -79.00670) The bench mark is a disk located about 165 m (540 ft) NW of Bench Mark GCB NO 2 1975, 25.15 m (82.5 ft) NW of the centerline of West Canal Drive, 8.44 m (27.7 ft) SW of the centerline of the highway, 5.12 m (16.8 ft) NE of underground telephone cable junction box #1C-5, and 1.46 m (4.8 ft) SE of utility pole #6 1/4 B. The bench mark is 0.03 m (0.1 ft) below ground level, crimped to the top of a copper-clad steel rod driven 13.7 m (45 ft) 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 5 Station ID: 8661419 PUBLICATION DATE: 02/13/2004 Name: GARDEN CITY BRRIDGE, MURRELLS INLET SC NOAA Chart: 11535 Latitude: 33° 34.7' N ( 33.57830) USGS Quad: BROOKGREEN Longitude: 79° 0.2' W ( -79.00330) T I D A L B E N C H M A R K S BENCH MARK STAMPING: GCB NO 4 1975 DESIGNATION: 866 1419 TIDAL GCB 4 MONUMENTATION: Tidal Station disk VM#: 3769 AGENCY: National Ocean Survey (NOS) IDB PID#: DD1491 SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID: LATITUDE: 33° 35.0' N ( 33.58330) LONGITUDE: 79° 0.5' W ( -79.00830) The bench mark is a disk located about 114 m (375 ft) NW of Bench Mark GCB NO 3 1975, 9.66 m (31.7 ft) SW of the centerline of the highway, 9.42 m (30.9 ft) NW of the centerline of East Bank Road, 6 m (20 ft) north of a lighted brick fence post on the north side of East Bank Road, and 0.98 m (3.2 ft) west of utility pole #B 5 1/2. The bench mark is 0.03 m (0.1 ft) below ground level, crimped to the top of a copper-clad steel rod driven 14.6 m (48 ft) to refusal, and encased in a 4-inch PVC pipe and concrete kickblock. BENCH MARK STAMPING: GCB NO 5 1975 DESIGNATION: 866 1419 TIDAL GCB 5 MONUMENTATION: Tidal Station disk VM#: 3770 AGENCY: National Ocean Survey (NOS) IDB PID#: DD1490 SETTING CLASSIFICATION: Copper-clad steel rod OPUS PID: LATITUDE: 33° 35.0' N ( 33.58330) LONGITUDE: 79° 0.5' W ( -79.00830) The bench mark is a disk located about 101 m (330 ft) NW of Bench Mark GCB NO 4 1975, 9.48 m (31.1 ft) NW of the centerline of Clubhouse Road, 8.99 m (29.5 ft) SW of the centerline of the highway, 3.32 m (10.9 ft) NW of a 1 m (4 ft) high lighted brick fence post on the north side of Clubhouse Road, and 0.52 m (1.7 ft) from the first brick fence post north of the lighted post. The bench mark is 0.03 m (0.1 ft) below ground level, crimped to the top of a copper-clad steel rod driven 14.6 m (48 ft) 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 4 of 5 Station ID: 8661419 PUBLICATION DATE: 02/13/2004 Name: GARDEN CITY BRRIDGE, MURRELLS INLET SC NOAA Chart: 11535 Latitude: 33° 34.7' N ( 33.57830) USGS Quad: BROOKGREEN Longitude: 79° 0.2' W ( -79.00330) T I D A L D A T U M S Tidal datums at GARDEN CITY BRRIDGE, MURRELLS INLET based on: LENGTH OF SERIES: 1 YEAR TIME PERIOD: December 1974 - November 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 (06/10/1975) = 2.015 MEAN HIGHER HIGH WATER MHHW = 1.457 MEAN HIGH WATER MHW = 1.336 North American Vertical Datum NAVD88 = 0.803 MEAN SEA LEVEL MSL = 0.696 MEAN TIDE LEVEL MTL = 0.687 MEAN LOW WATER MLW = 0.038 MEAN LOWER LOW WATER MLLW = 0.000 LOWEST OBSERVED WATER LEVEL (11/22/1975) = -0.191 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW GCB NO 1 1975 2.674 1.338 GCB NO 2 1975 3.003 1.667 GCB NO 3 1975 4.066 2.730 GCB NO 4 1975 4.340 3.004 GCB NO 5 1975 5.173 3.837
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 8661419 PUBLICATION DATE: 02/13/2004 Name: GARDEN CITY BRRIDGE, MURRELLS INLET SC NOAA Chart: 11535 Latitude: 33° 34.7' N ( 33.57830) USGS Quad: BROOKGREEN Longitude: 79° 0.2' W ( -79.00330) 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.