OPR-J311-KR-16 Eastern Vicinity of the Chandeleur Islands Southeastern Vicinity of the Chandeleur Islands David Evans and Associates, Inc. H12923 4 25 NM SE of Chandeleur Islands Mississippi United States 40000 2016 Jonathan L. Dasler, PE, PLS, CH Basic Hydrographic Survey 2016-07-15 2016-08-05 2016-11-17 Reson 7125 SV2 EdgeTech 4200-HF meters Universal Transverse Mercator (UTM) UTC Atlantic Hydrographic Branch NAD83, UTM Zone 16 North, Meters, Times are UTC. The purpose of this contract is to provide NOAA with modern, accurate hydrographic survey data with which to update nautical charts of the assigned area. Contractor David Evans and Associates, Inc. (DEA) conducted a hydrographic survey of the assigned area in the Gulf of Mexico, south of the Chandeleur Islands. Survey H12923 was conducted in accordance with the Statement of Work (July 15, 2016) and Hydrographic Survey Project Instructions (July 15, 2016). The Hydrographic Survey Project Instructions reference the National Ocean Service (NOS) Hydrographic Surveys Specifications and Deliverables Manual (HSSD), 2016 as the technical requirements for this project. 29.55305180 088.91970790 29.43801230 088.73657290 OPR-J311-KR-16 Assigned Survey Areas SupportFiles/OPR-J311-KR-16_AssignedSurveyAreas.png Survey Limits were surveyed in accordance with the requirements in the Project Instructions and the HSSD. The purpose of this project is to provide contemporary surveys to update National Ocean Service (NOS) nautical charting products. This project includes two survey areas totaling 263 SNM of which 226 SNM are classified as emerging critical areas, 32 SNM as priority two areas and 2 SNM as priority three as identified in the 2012 NOAA Hydrographic Survey Priorities. The first area is a narrow corridor located to the west of the Chandeleur Islands and extends from Baptiste Collette, LA towards Gulfport, MS. This corridor will serve as an alternate traffic route during the August 2016 closure of the INHC Lock in New Orleans. The second area, located to the east of the Chandeleur Islands, is a heavily trafficked area and encompasses approximately 125 SNM with multiple oil platforms and well heads. The entire survey is adequate to supersede previous data. All Sheet Numbers All MBES acquisition requires backscatter acquisition (refer to HSSD Section 6.2) Sheet Number 3 - 10 Complete Coverage (refer to HSSD Section 5.2.2.3) Complete coverage was obtained over the survey area using 100 percent side scan sonar coverage with concurrent multibeam echosounder (MBES) and backscatter. This coverage type follows Option B of the Complete Coverage requirement specified in Section 5.2.2.3 of the 2016 HSSD. Significant side scan sonar contacts were developed with multibeam sonar at object detection resolution as required by the coverage classification. Object detection multibeam coverage was obtained within the search radii (160 meters for charted features labeled with PA and 80 meters for charted features without a PA label) for all feature disapprovals. Survey coverage was obtained within the survey area depicted in the Project Reference File (PRF) OPR-J311-KR-16_PRF.000. Coverage was also obtained within the 160-meter search radius of a charted Wreck labelled as Position Approximate (PA) located outside of the survey area’s eastern border. Coverage was not required in the large hole in the center of the northern section of the survey area where contemporary survey coverage from survey F00546 already exists. H12923 Survey Outline SupportFiles/H12923_SurveyOutline.png S/V Blake 0.0 8.3 0.0 44.3 0.0 428.5 0.0 17.5 0.0 0.0 8.3 0.0 44.3 0.0 428.5 0.0 17.5 0.0 4.0 3 0 0 0 30.13 2016-08-05 2016-08-06 2016-08-07 2016-08-08 2016-08-12 2016-08-13 2016-08-19 2016-08-20 2016-11-17 The OPR-J311-KR-16 Data Acquisition and Processing Report (DAPR), previously submitted with survey H12920, details equipment and vessel information as well as data acquisition and processing procedures. There were no vessel or equipment configurations used during data acquisition that deviated from those described in the DAPR. S/V Blake 83 4.5 S/V Blake SupportFiles/Blake.png Reson 7125 SV2 MBES Edgetech 4200-HF SSS Applanix POS/MV 320 v5 Positioning & Attitude Rolls Royce MVP30-350 with AML Micro SV&P Primary Sound Speed Profiler AML Micro SV Xchange Surface Sound Speed Sea-Bird Electronics SEACAT SBE 19-03 CTD Secondary Sound Speed Profiler Crosslines were run across the entire survey area in order to provide a varied spatial and temporal distribution for analysis of internal consistency within the survey data. Crossline analysis was performed using the CARIS Hydrographic Information Processing System (HIPS) Quality Control (QC) Report tool, which compares crossline data to a gridded surface and reports results by beam number. Crosslines were compared to a 1-meter CUBE surface encompassing mainscheme data for the entire survey area. The QC Report tabular output and plot are included in Separate II. The results of the analysis meet the requirements as stated in the 2016 HSSD. Additional crossline analysis was performed by computing a 1-meter CUBE surface from the crossline data. The surface was then differenced from a 1-meter surface comprised of all mainscheme, fill, and investigation data. The resultant difference surface was exported using the Base Surface to ASCII function and statistics were compiled on the ASCII data. Results from the crossline to mainscheme difference analysis are depicted in Figure 4. Outliers from the difference analysis were reviewed in HIPS subset editor and found to result from a combination of sound speed and tide artifacts. H12923 Crossline Differences SupportFiles/H12923_XL_MS.png 0.00 0.112 Discrete S/V Blake n/a 1.0 0.5 Additional discussion of these parameters is included in the DAPR. During surface finalization in HIPS, the "Greater of the two values” option was selected, where the calculated uncertainty from total propagated uncertainty (TPU) is compared to the standard deviation of the soundings influencing the node, and where the greater value is assigned as the final uncertainty of the node. The uncertainty of the finalized surfaces increased for nodes where the standard deviation of the node was greater than the total propagated uncertainty. The resulting calculated uncertainty values of all nodes in the finalized 1-meter Complete Coverage multibeam surface range from 0.235 meters to 1.123 meters with a standard deviation of 0.013 meters. To determine if surface grid nodes met International Hydrographic Organization (IHO) Order 1 specification, a ratio of the final node uncertainty to the allowable uncertainty at that depth was determined. As a percentage, this value represents the amount of error budget utilized by the uncertainty value at each node. Values greater than 100% indicate nodes exceeding the allowable IHO uncertainty. For the 1-meter Complete Coverage multibeam surface, the allowable uncertainty utilized ranges from 42% to 203%. The mean allowable uncertainty for the surface is 46% with a standard deviation of 0.023. Survey H12923 junctions with surveys F00546, H12735, H12736, H12921, H12922, H12924, and H12925. The Bathymetric Attributed Grid (BAG) for survey F00546 was downloaded from NOAA's National Centers for Environmental Information (NCEI) website for comparison with H12923. The junction analyses with surveys H12735 and H12736, which were not available on the NCEI website, used data from other sources. A preliminary BAG for survey H12735 and H12736 was provided by HSD for use during the junction analysis with this survey. The finalized H12923 surface was compared to each junction survey by generating a difference surface with CARIS HIPS. At the time of writing, data from surveys H12924 and H12925 were still being processed. The Descriptive Reports for these respective surveys will include the junction analysis with H12923. F00546 40000 2007 C & C Technologies, Inc. W H12923 survey depths generally range from 30 centimeters deeper than F00546 to 20 centimeters shoaler than F00546. The bimodal distribution, observed in the histogram of differences appears to be caused by systematic errors in the F00546 survey where soundings from adjacent survey lines from the prior survey are alternately shoaler than and deeper than H12923 survey depths. The minimum (H12923 up to 40 centimeters shoaler than F00546) and maximum (H12923 up to 1.25 meters deeper than F00546) reported differences appear to result from a combination of natural seafloor change, which has occurred since the prior survey, and systematic artifacts observed in the prior survey. Without access to the prior survey’s processed data the hydrographer is unable to determine the cause of the systematic offset. Junction results between H12923 1-meter and F00546 2-meter bathy grids SupportFiles/H12923_1m_F00546_2m_Junction.png H12735 20000 2015 Oceans Surveys, Inc. S The mean difference between H12923 and H12735 survey depths is 29 centimeters (H12923 deeper than H12735). It appears that the bias between the two surveys results from the use of disparate tide zoning schemes. Prior survey H12735 used zoning correctors from the NWLON gauge Pilots Station East, SW Pass, LA (8760922) while survey H12923 was controlled from the NWLON gauge Dauphin Island (8735180). DEA requested a copy of the tide zoning scheme used to correct surveys H12735 and H12736 from the HSD Operations Branch in order to investigate the bias observed between H12923 and the junction surveys. Zoned water levels were created for zone CGM124, which is the zone encompassing the survey junction, during the timeframe of the H12735 survey (June 2015 to July 2015). Water levels zoned from Pilots Station East to zone CGM124 are consistently higher than those zoned from Dauphin Island with an increasing trend in the differences over the time period of the analysis. A raw survey depth measured within zone CGM124 and corrected with data from Pilots Station East would be shoaler than the same depth corrected from Dauphin Island. A plot of the differences between the zoned water levels from CGM124 (with linear trend line) are presented in Figure 7. Junction results between H12923 1-meter and H12735 4-meter bathy grids SupportFiles/H12923_1m_H12735_4m_Junction.png Zone CGM124 Water Level Differences SupportFiles/CGM124 Zoning Comparison.png H12736 40000 2015 Oceans Surveys, Inc. S The mean difference between H12923 and H12736 survey depths is 29 centimeters (H12923 deeper than H12736). As with the H12735 junction, it appears that the bias between the two surveys results from the use of disparate tide zoning schemes. Survey H12736 used zoning correctors from the NWLON gauge Pilots Station East, SW Pass, LA (8760922) while survey H12923 was controlled from the NWLON gauge Dauphin Island (8735180). The junction between H12736 and H12923 falls within zones CGM120 and CGM124. Water levels for zone CGM120 were analyzed using the same process used for CGM124 during the H12735 junction analysis. Results are similar where water levels zoned from Pilots Station East are consistently higher than those zoned from Dauphin Island. A plot of the differences between the zoned water levels (with linear trend line) are presented in Figure 10. Junction results between H12923 1-meter and H12736 1-meter bathy grids SupportFiles/H12923_1m_H12736_4m_Junction.png Zone CGM120 Water Level Differences SupportFiles/CGM120 Zoning Comparison.png H12921 40000 2016 David Evans and Associates, Inc. W The mean difference between H12923 and H12921 survey depths is 3 centimeters (H12923 deeper than H12921). The minimum and maximum differences are associated with sound speed and tide artifacts. Junction results between H12923 1-meter and H12921 50-centimeter bathy grids SupportFiles/H12923_1m_H12921_50cm_Junction.png H12922 40000 2016 David Evans and Associates, Inc. W H12923 survey depths generally range from 5-6 centimeters deeper than H12922 to 3-4 centimeters shoaler than H12922. The minimum and maximum differences are associated with sound speed and tide artifacts. Junction results between H12923 1-meter and H12922 1-meter bathy grids SupportFiles/H12923_1m_H12922_1m_Junction.png H12924 40000 2016 David Evans and Associates, Inc. N The junction analysis between H12924 and H12923 will be included in the H12924 DR. H12925 40000 2016 David Evans and Associates, Inc. N The junction analysis between H12925 and H12923 will be included in the H12925 DR. Quality control is discussed in detail in Section B of the DAPR. Results from weekly position checks and weekly multibeam bar checks are included in Separate I Acquisition and Processing Logs of this report. Sound speed checks can be found in Separate II Sound Speed Data Summary of this report. Multibeam data were reviewed at multiple levels of data processing including: CARIS HIPS conversion, subset editing, and analysis of anomalies revealed in CUBE surfaces. Navigation Data Gaps Periodically, survey lines contained navigation gaps which were likely caused by a Hypack write delay during acquisition. Survey lines containing navigation data gaps greater than one second were updated with real-time DGPS/Inertial position data extracted from the POS/MV .000 files. The following survey lines use real-time DGPS/Inertial position data from .000 files: 2016BL2200951, 2016BL2201402, 2016BL2251646 Minor sound speed and discrete zoning artifacts Occasional sound speed and discrete zoning artifacts approaching 20 centimeters in magnitude are present in the survey data. Though these issues impacted some soundings, all data meet requirements outlined in the HSSD. Approximately 15-minute intervals. A Rolls Royce Moving Vessel Profiler (MVP) was the primary instrument used to acquire sound speed readings during multibeam operations. MVP sound speed readings were measured at approximately 15-minute intervals during survey operations. Additional discussion of sound speed methods can be found in the DAPR. Survey speeds were maintained to meet or exceed along-track sounding density and side scan sonar ensonification requirements. Side scan mosaics were thoroughly reviewed for holidays and areas of poor quality coverage due to biomass, vessel wakes, or other factors. A fill plan was created in order to acquire side scan data where holidays and significant poor quality coverage existed. Side scan sonar contacts were developed with multibeam sonar to obtain a least depth of the contact using Object Detection Coverage requirements. Density The sounding density requirement of 80% of all nodes, populated with at least five soundings per node, was verified by exporting the density child layer of the finalized CUBE surface to an ASCII text file and compiling statistics on the density values. More than 98% of all final CUBE surface nodes contained five or more soundings. Data reduction procedures for survey H12923 are detailed in the DAPR. A summary multibeam processing log is included in Separate I of this report. No additional calibration tests were conducted beyond those discussed in the DAPR. Multibeam backscatter was logged in Hypack 7K format and included with the H12923 digital deliverables. Data were processed periodically in CARIS HIPS to evaluate backscatter quality but the processed data is not included with the deliverables. For data management purposes, the names of multibeam crosslines have been appended with the suffix _XL. This change was made to HIPS files only. The original file names of raw data files (Hypack HSX and 7k) have been retained. CARIS HIPS 9.1.6 Chesapeake Technology, Inc. SonarWiz 6.004.0006 and 6.004.0009 5.3.4. A detailed listing of all data processing software is included in the OPR-J311-KR-16 DAPR. H12923_MB_1m_MLLW CUBE 1 12.61 21.20 NOAA_1m Complete Coverage H12923_MB_1m_MLLW_Final CUBE 1 12.61 21.20 NOAA_1m Finalized Complete Coverage H12923_SSS_1m_100 Mosaic 1 0 0 N/A 100- percent coverage Bathymetric grids were created relative to Mean Lower Low Water (MLLW) in CUBE format using Complete Coverage resolution requirements as described in the HSSD. A complete description of the horizontal and vertical control for survey H12923 can be found in the OPR-J311-KR-16 Horizontal and Vertical Control Report (HVCR), submitted under a separate cover. A summary of horizontal and vertical control for this survey follows. The horizontal datum for the project was the North American Datum of 1983 (NAD 83) as specified by Hydrographic Technical Directive (HTD) 2016-3: Revision of Horizontal Datum in 2016 HSSD. A copy of this HTD is included in the OPR-J311-KR-16 Project Correspondence. Mean Lower Low Water Dauphin Island 8735180 8735180.tid Verified Observed J311KR2016RevCORP.zdf Final Tide zoning file J311KR2016RevCORP.zdf was provided with the project instructions and used for sounding correction within the assigned survey area. North American Datum of 1983 (NAD83) NAD83 UTM Zone 16 North English Turn, LA (293 kHz) The majority of the chart comparison was performed by comparing H12923 depths to a digital surface generated from electronic navigational charts (ENCs) covering the survey area. A 50-meter product surface was generated from a triangular irregular network (TIN) created from the soundings, depth contours, and depth features for each ENC scale. An additional 50-meter HIPS product surface of the entire survey area was generated from the finalized MBES CUBE surfaces. The chart comparison was conducted by creating and reviewing the resultant difference surface. The chart comparison also included a review of all assigned charted features within the survey area. The raster navigational chart (RNC) comparison was performed by manually comparing the RNC covering the survey area to the corresponding ENC and identifying discrepancies between the two chart formats. The electronic and raster versions of the relevant charts used during the comparison were reviewed to check that all US Coast Guard (USCG) Local Notice to Mariners (LNMs) issued during survey acquisition and impacting the survey area were applied and addressed by this survey. 11363 1 80000 44 2013-02 2016-10-29 2016-11-15 Approach chart 11363 was compared to US4LA34M within the H12923 survey area. No differences were observed between the charts. 11366 1 250000 16 2015-06 2016-10-29 2016-11-15 General Chart was compared to US3GC04M within the H12923 survey area. No differences were observed between the charts. US4LA34M 80000 29 2015-01-06 2016-11-03 false In general, surveyed depths range from five feet deeper to four feet shoaler than charted on ENC US4LA34M. Survey depths are up to 22 feet deeper than charted in the vicinity of the disproved charted Wreck PA (38-foot reported), which is located outside of the assigned survey area. Depth Difference between H12923 and chart US4LA34M SupportFiles/H12923_ChartComp_US4LA34M.png US3GC04M 250000 52 2014-11-05 2016-11-03 false In general, surveyed depths range from five feet deeper to three feet shoaler than charted on ENC US3GC04M. Survey depths are up to 22 feet deeper than charted in the vicinity of the disproved charted Wreck PA (6-fathom 2-foot reported), which is located outside of the assigned survey area. Depth Difference between H12923 and chart US3GC04M SupportFiles/H12923_ChartComp_US3GC04M.png No Maritime Boundary Points were assigned for this survey. The Wreck PA (38-foot reported) has been disproved with Object Detection MBES coverage and is included in the FFF with a description of ‘Delete’. The survey area does not contain any charted features labeled as Reported, Position Doubtful (PD), or Existence Doubtful (ED). There were no uncharted features located by the survey. 1 One Danger to Navigation (DtoN) was submitted for this survey. H12923 DtoN 01 reported a section of pipeline which is visibly exposed on the seabed in the multibeam data. While not a direct hazard to surface navigation this exposed pipeline was submitted using the DtoN process in order to facilitate the review and reporting of the exposed pipeline. No shoal or hazardous features were charted or located within the H12923 survey area. The H12923 survey area encompasses portions of a charted safety fairway (33 CFR 166.200) and a charted fairway anchorage (33 CFR 166.200). There are no maintained navigation channels or channel lines within the survey area. Three bottom samples were acquired on August 19, 2016 (DN232). The sampling plan followed suggested sample locations included in the PRF provided by the Hydrographic Surveys Division. Shoreline investigation was not assigned for this survey. Other than the previously mentioned junction analyses, no other comparisons with prior surveys were conducted. No Aids to Navigation (AtoNs) were charted or located within the H12923 survey area. There were no overhead bridges, cables, or other structures which would impact overhead clearance in the survey area. Sections of pipeline which are visibly exposed on the seabed were reported as a DtoN and are included in the H12923 FFF as pipeline features. These features were submitted to the processing branch using the DtoN process so that the proper authorities could be notified about the condition of the pipelines. No submarine cables or tunnels were charted or located within the H12923 survey area. There were no ferry routes or terminals within the survey area. Thirteen platforms are charted within the survey area. Four of the charted platforms were found within 80 meters (2 millimeters at survey scale) of their charted position and have been included in the FFF with a description of ‘Retain’. Nine of the charted platforms were disproved by the survey and are included in the FFF with description of ‘Delete’. All platforms were disproved with Object Detection MBES coverage. There was no other information of scientific or practical value observed during the survey. No construction or dredging activities were observed during survey operations. No new surveys or further investigations are recommended for this area. No new insets are recommended for this area. As Chief of Party, field operations for this hydrographic survey were conducted under my direct supervision, with frequent personal checks of progress and adequacy. I have reviewed the attached survey data and reports. All field sheets, this Descriptive Report, and all accompanying records and data are approved. All records are forwarded for final review and processing to the Processing Branch. The survey data meets or exceeds requirements as set forth in the NOS Hydrographic Surveys and Specifications Deliverables Manual, Statement of Work, and Hydrographic Survey Project Instructions. These data are adequate to supersede charted data in their common areas. This survey is complete and no additional work is required. Jonathan L. Dasler, PE, PLS, CH NSPS/THSOA Certified Hydrographer, Chief of Party 2017-01-06 Jason Creech, CH NSPS/THSOA Certified Hydrographer, Charting Manager / Project Manager 2017-01-06 Kathleen Schacht MBES Data Processing Manager 2017-01-06 David T. Moehl, CH, LSIT Lead Hydrographer 2017-01-06 OPR-J311-KR-16 Data Acquisition and Processing Report 2016-11-03