U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 Station ID: 8761742 PUBLICATION DATE: 04/27/2018 Name: MENDICANT ISLAND, BARATARIA BAY LA NOAA Chart: 11364 Latitude: 29° 19.1' N ( 29.31830) USGS Quad: BARATARIA PASS Longitude: 89° 58.8' W ( -89.98000) To reach the tidal bench marks from Rigaud Marina at the east end of Grand Isle, proceed by boat north along Barataria Bay Waterway for 7.6 km (4.7 mi) to Mendicant Island, then turn right at Channel Marker #13 into the first dredged channel east of the waterway, and proceed to Texaco, Inc., Unit 4, Well #2 platform. The bench marks are on a section of marsh SW of the platform and along the west bank of an unnamed bayou. The tide gage and staff were located in the vicinity of the well head on the west end of the catwalk. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 1742 A 1985 DESIGNATION: 876 1742 A TIDAL MONUMENTATION: Tidal Station disk VM#: 7189 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Stainless steel rod OPUS PID: LATITUDE: 29° 19.1' N ( 29.31830) LONGITUDE: 89° 58.8' W ( -89.98000) The primary bench mark is a disk located south of the well head in the marsh, 18.20 m (59.7 ft) SE of the toe of an old spoil bank, 5.94 m (19.5 ft) SW of a 2-inch wood post standing 2 m (7 ft) above the marsh, 4.45 m (14.6 ft) east of a 1-inch wood stake standing 2 m (7 ft) above the marsh, and 0.30 m (1.0 ft) east of a witness post. The bench mark is set 0.43 m (1.4 ft) above ground level, crimped to the top of a stainless steel rod driven 24.4 m (80 ft) to substantial resistance, and encased in a 5-inch PVC pipe extending 0.67 m (2.2 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 Station ID: 8761742 PUBLICATION DATE: 04/27/2018 Name: MENDICANT ISLAND, BARATARIA BAY LA NOAA Chart: 11364 Latitude: 29° 19.1' N ( 29.31830) USGS Quad: BARATARIA PASS Longitude: 89° 58.8' W ( -89.98000) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 1742 B 1985 DESIGNATION: 876 1742 B TIDAL MONUMENTATION: Tidal Station disk VM#: 7190 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Stainless steel rod OPUS PID: LATITUDE: 29° 19.1' N ( 29.31830) LONGITUDE: 89° 58.8' W ( -89.98000) The bench mark is a disk located 75.96 m (249.2 ft) SW of bench mark 1742 A 1985, 12 m (38 ft) WNW of the west bank of an unnamed bayou, 4.08 m (13.4 ft) SW of a 2-inch wood post standing 2 m (7 ft) above the marsh, 4 m (13 ft) NE of the north shoreline of a small channel running perpendicular to the unnamed bayou, and 0.27 m (0.9 ft) east of a witness post. The bench mark is set 0.43 m (1.4 ft) above ground level, crimped to the top of a stainless steel rod driven 24.4 m (80 ft) to substantial resistance, and encased in a 5-inch PVC pipe extending 0.67 m (2.2 ft) above ground level. BENCH MARK STAMPING: 1742 C 1985 DESIGNATION: 876 1742 C TIDAL MONUMENTATION: Tidal Station disk VM#: 7191 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Stainless steel rod OPUS PID: LATITUDE: 29° 19.1' N ( 29.31830) LONGITUDE: 89° 58.8' W ( -89.98000) The bench mark is a disk located 76 m (249.0 ft) south of bench mark 1742 B 1985, 11 m (37 ft) west of the bank of an unnamed bayou as marked by a 1-inch wood stake standing 1 m (3 ft) above the marsh, 3.63 m (11.9 ft) south of a 2-inch wood post standing 2 m (7 ft) above the marsh, and 0.3 m (1.0 ft) east of a witness post. The bench mark is set 0.43 m (1.4 ft) above ground level, crimped to the top of a stainless steel rod driven 21.9 m (72 ft) to substantial resistance, and encased in a 5-inch PVC pipe extending 0.64 m (2.1 ft) above ground level.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 Station ID: 8761742 PUBLICATION DATE: 04/27/2018 Name: MENDICANT ISLAND, BARATARIA BAY LA NOAA Chart: 11364 Latitude: 29° 19.1' N ( 29.31830) USGS Quad: BARATARIA PASS Longitude: 89° 58.8' W ( -89.98000) T I D A L B E N C H M A R K S BENCH MARK STAMPING: 1742 D 1985 DESIGNATION: 876 1742 D TIDAL MONUMENTATION: Tidal Station disk VM#: 7192 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Stainless steel rod OPUS PID: LATITUDE: 29° 19.1' N ( 29.31830) LONGITUDE: 89° 58.8' W ( -89.98000) The bench mark is a disk located 75.65 m (248.2 ft) south of bench mark 1742 C 1985, 7.10 m (23.3 ft) ENE of a 2-inch wood post standing 2 m (7 ft) above the marsh, 6.43 m (21.1 ft) SW of a 1-inch wood stake set on the bank and standing 1 m (3 ft) above the marsh, 6 m (20 ft) NW of the bank of the unnamed bayou, and 0.18 m (0.6 ft) ENE of a witness post. The bench mark is set 0.43 m (1.4 ft) above ground level, crimped to the top of a stainless steel rod driven 23.2 m (76 ft) to substantial resistance, encased in a 5-inch PVC pipe extending 0.61 m (2.0 ft) above ground level, and surrounded by a cylindrical concrete kickblock. BENCH MARK STAMPING: 1742 E 1985 DESIGNATION: 876 1742 E TIDAL MONUMENTATION: Tidal Station disk VM#: 7193 AGENCY: National Ocean Service (NOS) IDB PID#: SETTING CLASSIFICATION: Stainless steel rod OPUS PID: LATITUDE: 29° 19.1' N ( 29.31830) LONGITUDE: 89° 58.8' W ( -89.98000) The bench mark is a disk located 76.05 m (249.5 ft) SSE of bench mark 1742 D 1985, 7.25 m (23.8 ft) WSW of the bank of an unnamed bayou, 5.97 m (19.6 ft) NE of a 1 by 6-inch cypress plank standing 1 m (3 ft) above the marsh, 3.60 m (11.8 ft) NNW of a 1-inch wood stake standing 2 m (7 ft) above the marsh, and 0.21 m (0.7 ft) east of a witness post. The bench mark is set 0.37 m (1.2 ft) above ground level, crimped to the top of a stainless steel rod driven 20.7 m (68 ft) to refusal, encased in a 5-inch PVC pipe extending 0.52 m (1.7 ft) above ground level, and surrounded by a cylindrical concrete kickblock.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 Station ID: 8761742 PUBLICATION DATE: 04/27/2018 Name: MENDICANT ISLAND, BARATARIA BAY LA NOAA Chart: 11364 Latitude: 29° 19.1' N ( 29.31830) USGS Quad: BARATARIA PASS Longitude: 89° 58.8' W ( -89.98000) T I D A L D A T U M S Tidal datums at MENDICANT ISLAND, BARATARIA BAY based on: LENGTH OF SERIES: 1 YEAR TIME PERIOD: September 1985 - August 1986 TIDAL EPOCH: 2012-2016 CONTROL TIDE STATION: 8761724 GRAND ISLE, EAST POINT Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in METERS: HIGHEST OBSERVED WATER LEVEL (10/28/1985) = 1.315 MEAN HIGHER HIGH WATER MHHW = 0.305 MEAN HIGH WATER MHW = 0.303 MEAN SEA LEVEL MSL = 0.155 MEAN TIDE LEVEL MTL = 0.153 MEAN LOW WATER MLW = 0.003 MEAN LOWER LOW WATER MLLW = 0.000 LOWEST OBSERVED WATER LEVEL (01/27/1986) = -0.639 North American Vertical Datum (NAVD88) Bench Mark Elevation Information In METERS above: Stamping or Designation MLLW MHW 1742 A 1985 0.404 0.101 1742 B 1985 0.418 0.115 1742 C 1985 0.372 0.069 1742 D 1985 0.503 0.200 1742 E 1985 0.376 0.073
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 Station ID: 8761742 PUBLICATION DATE: 04/27/2018 Name: MENDICANT ISLAND, BARATARIA BAY LA NOAA Chart: 11364 Latitude: 29° 19.1' N ( 29.31830) USGS Quad: BARATARIA PASS Longitude: 89° 58.8' W ( -89.98000) 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.