U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Datums Page Page 1 of 5 PUBLICATION DATE: 01/30/1990 Station ID: 8760595 SUPERCEDED DATE: 04/21/2003 Name: BRETON ISLAND, BRETON SOUND LOUISIANA NOAA Chart: 11363 Latitude: 29° 29.6' N USGS Quad: BRETON ISLANDS Longitude: 89° 10.4' W To reach the tidal bench marks from Venice, proceed by boat across the Mississippi River, then NE on Baptiste Collette Bayou for 8 miles (13 km) to the end of the channel markers, then NE across Breton Sound for 11 miles (18 km) to the Kerr-McGee oil facility on Breton Island. The bench marks are on the grounds of the oil facility and in the marsh to the north. The tide gage and staff were on the west side and NW corner, respectively, of the T-shaped wooden dock. T I D A L B E N C H M A R K S PRIMARY BENCH MARK STAMPING: 0595 A 1980 MONUMENTATION: Survey Disk VM#: 7089 AGENCY: PID: SETTING CLASSIFICATION: Stainless Steel Rod The bench mark is in the marsh NE of the circular bulkhead around the oil facility, 200 feet (61 m) NNE of Corps of Engineers (COE) Bench Mark NO STAMPING 1, 182 feet (55 m) NNE of the bulkhead around the oil facility, 98 feet (30 m) north of the NE anchor pile of the radio tower guy wire system, and 80 feet (24 m) west of the west shoreline of the bay inside the east side of the island. The bench mark is 0.3 foot (0.1 m) below ground level, crimped to a stainless steel rod driven 50 feet (15 m) to refusal, and encased in a 4-inch PVC pipe. BENCH MARK STAMPING: 0595 B 1980 MONUMENTATION: Survey Disk VM#: 7090 AGENCY: PID: SETTING CLASSIFICATION: Stainless Steel Rod The bench mark is in the marsh, 385 feet (117 m) NNE of the west radio tower guy wire anchor, 369 feet (112 m) north of COE Bench Mark NO STAMPING 2, 360 feet (110 m) north of the circular bulkhead around the oil facility, 311 feet (95 m) NNW of the NE radio tower guy wire anchor, 219 feet (67 m) NNW of Bench Mark 0595 A 1980, and 58 feet (18 m) south of the shoreline of the small bay which is north of the oil facility. The bench mark is 0.2 foot (0.1 m) below ground level, crimped to a stainless steel rod driven 55 feet (17 m) to refusal, and encased in a 4-inch PVC pipe.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 2 of 5 PUBLICATION DATE: 01/30/1990 Station ID: 8760595 SUPERCEDED DATE: 04/21/2003 Name: BRETON ISLAND, BRETON SOUND LOUISIANA NOAA Chart: 11363 Latitude: 29° 29.6' N USGS Quad: BRETON ISLANDS Longitude: 89° 10.4' W T I D A L B E N C H M A R K S BENCH MARK STAMPING: 0595 C 1980 MONUMENTATION: Survey Disk VM#: 7091 AGENCY: PID: SETTING CLASSIFICATION: Stainless Steel Rod The bench mark is in the marsh, 350 feet (107 m) WNW of the NW radio tower guy wire anchor, 306 feet (93 m) NW of COE Bench Mark NO STAMPING 2, 281 feet (86 m) NNW of the circular bulkhead around the oil facility, 251 feet (77 m) SW of Bench Mark 0595 B 1980, 140 feet (43 m) north of the west anchor pile of the radio tower, and 59 feet (18 m) north of the NW end of the facility. The bench mark is 0.3 foot (0.1 m) below ground level, crimped to a stainless steel rod driven 60 feet (18 m) to refusal, and encased in a 4-inch PVC pipe. BENCH MARK STAMPING: BRETON RM NO 2 MONUMENTATION: Survey Disk VM#: 7092 AGENCY: PID: SETTING CLASSIFICATION: Concrete Monument The bench mark is on the west side of the oil facility near the NW radio tower guy wire anchor, 17 feet (5 m) NW of the NW corner of a generator house, and 2 feet (1 m) east of the bulkhead.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 3 of 5 PUBLICATION DATE: 01/30/1990 Station ID: 8760595 SUPERCEDED DATE: 04/21/2003 Name: BRETON ISLAND, BRETON SOUND LOUISIANA NOAA Chart: 11363 Latitude: 29° 29.6' N USGS Quad: BRETON ISLANDS Longitude: 89° 10.4' W T I D A L B E N C H M A R K S BENCH MARK STAMPING: NO STAMPING 1 MONUMENTATION: Survey Disk VM#: 7093 AGENCY: PID: SETTING CLASSIFICATION: Concrete Monument The bench mark is set in a concrete monument at the foot of the dock on the east side of the oil facility, 66.5 feet (20.3 m) NE of the centerline of a concrete ramp leading SSE from the island, 21.8 feet (6.6 m) south of the centerline of the wood ramp leading east to the wooden dock, 18.5 feet (5.6 m) ESE of the NE corner of the metal generator building, 5.0 feet (1.5 m) west of the outside face of the circular bulkhead around the oil facility, and 0.5 foot (0.2 m) above ground level. BENCH MARK STAMPING: NO STAMPING 2 MONUMENTATION: Survey Disk VM#: 7094 AGENCY: PID: SETTING CLASSIFICATION: Concrete Monument The bench mark is on the north side of the oil facility, 131.5 feet (40.1 m) SW of the NE guy wire post for the antenna tower on the west side of the island, 93.8 feet (28.6 m) NE of the center of the concrete base of the antenna tower, 13.6 feet (4.1 m) NE of the NW corner of the metal walkway along the north side of the crew quarters, 7.6 feet (2.3 m) south of the outside face of the circular bulkhead around the oil facility, and 0.7 foot (0.2 m) above ground level.
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 4 of 5 PUBLICATION DATE: 01/30/1990 Station ID: 8760595 SUPERCEDED DATE: 04/21/2003 Name: BRETON ISLAND, BRETON SOUND LOUISIANA NOAA Chart: 11363 Latitude: 29° 29.6' N USGS Quad: BRETON ISLANDS Longitude: 89° 10.4' W T I D A L D A T U M S Tidal datums at BRETON ISLAND, BRETON SOUND based on: LENGTH OF SERIES: 9 MONTHS TIME PERIOD: MARCH - DECEMBER 1981 TIDAL EPOCH: 1960-1978 CONTROL TIDE STATION: 8747437 BAY WAVELAND, MS Elevations of tidal datums referred to Mean Lower Low Water (MLLW), in FEET: HIGHEST OBSERVED WATER LEVEL (05/05/1981) = 2.70 MEAN HIGHER HIGH WATER MHHW = 1.32 MEAN HIGH WATER MHW = 1.30 MEAN TIDE LEVEL MTL = 0.66 MEAN LOW WATER MLW = 0.01 MEAN LOWER LOW WATER MLLW = 0.00 LOWEST OBSERVED WATER LEVEL (02/04/1981) = -1.30 Bench Mark Elevation Information In FEET above: Stamping or Designation MLLW MHW 0595 A 1980 1.75 0.45 0595 B 1980 1.60 0.30 0595 C 1980 2.93 1.63 BRETON RM NO 2 6.31 5.01 NO STAMPING 1 7.42 6.12 NO STAMPING 2 7.23 5.93
U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Ocean Service Page 5 of 5 PUBLICATION DATE: 01/30/1990 Station ID: 8760595 SUPERCEDED DATE: 04/21/2003 Name: BRETON ISLAND, BRETON SOUND LOUISIANA NOAA Chart: 11363 Latitude: 29° 29.6' N USGS Quad: BRETON ISLANDS Longitude: 89° 10.4' 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.