OPR-J311-KR-14 Western Vicinity of Lake Borgne Western Vicinity of Lake Borgne David Evans and Associates, Inc. H12711 4 String 3NM West of Chandeleur Islands Louisiana United States 40000 2014 Jonathan L. Dasler, PE, PLS, CH Basic Hydrographic Survey 2014-08-29 2014-12-06 2015-06-02 Reson 7125 SV2 EdgeTech 4200-HF meters Universal Transverse Mercator (UTM) UTC Atlantic Hydrographic Branch NAD83, UTM Zone 16, 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 hydrographic survey operations in Chandeleur Sound approximately three nautical miles west of the Chandeleur Islands. Survey H12711 was conducted in accordance with the Statement of Work (July 9, 2014) and Hydrographic Survey Project Instructions (August 29, 2014). The Hydrographic Survey Project Instructions reference the National Ocean Service (NOS) Hydrographic Surveys Specifications and Deliverables Manual (HSSD), April 2014 as the technical requirements for this project. 30.081899 88.954389 29.979627 88.864965 OPR-J311-KR-14 Assigned Survey Areas SupportFiles/H12711_AssignedSurveyAreas.png Survey Limits were acquired 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 is located in an area subject to the influence of hurricanes on an annual basis, thus producing a very dynamic environment requiring frequent re-surveying. In addition, the tug and tow industry will be re-routed to the west of the Chandeleur Islands due to a Gulf Intracoastal Waterway West (GIWW) closure in the Summer of 2015. A large portion of the proposed alternative route for the tug and tow industry lies within the southern portion of this project area. This project will cover approximately 129 SNM of emerging critical areas and 4.5 SNM of priority 2 areas as identified in the 2012 NOAA Hydrographic Survey Priorities (NHSP). The project area is located in the vicinity of Lake Borgne, the Gulfport Sound Channel, and west of the Chandeleur Islands. The entire survey is adequate to supersede previous data. The survey consisted of 200% side scan sonar coverage with concurrent multibeam echosounder (MBES) and backscatter using the Set Line Spacing coverage technique. Significant side scan sonar contacts were developed with multibeam sonar to meet Object Detection coverage requirements for multibeam surveys. This inshore limit of the survey was defined as the farthest offshore of either the surveyed 4-meter depth contour or the Navigable Area Limit Line (NALL) defined in the OPR-J311-KR-14 Project Reference File (PRF). DEA received a waiver to use the full sonar range when the towfish altitude was less than 8% of the range scale when operating at the 50-meter range scale. This waiver removed the minimum towfish height requirement at the 50-meter range scale as specified in Section 6.1.2.3 of the HSSD. A copy of the email correspondence granting this waiver is included in OPR-J311-KR-14 Project Correspondence. H12711 Survey Outline SupportFiles/H12711_SurveyOutline.png S/V Blake 0 11.70 0 14.01 0 1000.19 0 81.20 0 0.0 11.7 0.0 14.01 0.0 1000.19 0.0 81.2 0.0 8.02 7 0 0 0 0 21.40 2014-12-06 2014-12-07 2014-12-09 2014-12-10 2014-12-11 2014-12-12 2014-12-13 2014-12-14 2014-12-15 2014-12-16 2015-03-11 2015-03-12 2015-03-13 2015-04-07 2015-04-08 2015-04-10 2015-04-14 2015-04-15 2015-06-02 The OPR-J311-KR-14 Data Acquisition and Processing Report (DAPR), previously submitted with survey H12708, details equipment and vessel information as well as data acquisition and processing procedures used during this survey. 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/SV_Blake.png Reson 7125 SV2 MBES Edgetech 4200-HF SSS Applanix POS/MV 320 v4 Positioning & Attitude Rolls Royce MVP30-350 with AML Micro SVP&T Primary Sound Speed Profiler AML Micro SV Exchange Surface Sound Speed Sea-Bird Electronics SEACAT SBE 19-03 CTD Secondary Sound Speed Profiler AML SV Plus V2 Secondary Sound Speed Profiler Crosslines were run in a direction perpendicular to main scheme lines across the entire surveyed area, providing a good representation for analysis of consistency. All crosslines were used for crossline comparisons. 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 4-meter CUBE surface encompassing mainscheme data for the entire survey area. The QC Report tabular output and plot are included in Separate II Digital Data. The results of the analysis meet the requirements as stated in the 2014 HSSD. Additional crossline analysis was performed by computing a 4-meter CUBE surface from the crossline data. The surface was then differenced from a 4-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. Maximum differences greater than 30 centimeters occurred in an area of high relief on the eastern side of the survey area. These differences were artifacts of producing a course resolution gridded bathymetric surface over steep slopes. Less extreme differences which were distributed throughout northern and western sides of the survey area resulted from a combination of sound speed artifacts in the outer beams and tide zoning errors. H12711 Crossline Differences SupportFiles/H12711_XL_MS.png 0.000 0.102 S/V Blake n/a 1 0.5 Additional discussion of these parameters is included in the DAPR. During surface finalization in HIPS, the "greater of the two” 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 4-meter Set Line Spacing multibeam surface range from 0.209 meters to 0.329 meters with a standard deviation of 0.004 meters. The uncertainty values of all nodes in the finalized 50-centimeter Object Detection multibeam surface range from 0.209 meters to 1.522 meters with a standard deviation of 0.029 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 4-meter Set Line Spacing multibeam surface, the allowable uncertainty utilized ranges from 40% to 65%. The mean allowable uncertainty for the surface is 42% with a standard deviation of 0.008. For the 50-centimeter Object Detection multibeam surface, the allowable uncertainty utilized ranges from 40% to 295%. The mean allowable uncertainty for the surface is 42% with a standard deviation of 0.057. In total 973 nodes out of 445,765 fail to meet specification. Nodes that were reported out of specification were coincident with areas of high depth standard deviation over significant features with steep slopes. All uncertainty values were within allowable specification prior to surface finalization when standard deviation was incorporated into the solution when it was greater than the node uncertainty. Survey H12711 junctions with surveys H12712, H12720, H12721, H12528 and D00140. Surveys H12712, H12720, and H12721 were also performed by DEA as part of project OPR-J311-KR-14. Survey H12528 was performed by DEA during project OPR-J348-KR-13. Prior survey D00140 was a hydrographic reconnaissance survey which used a vertical beam echosounder with 1,000 meter line spacing to evaluate chart adequacy. The Bathymetric Attributed Grid (BAG) for survey D00140 was downloaded from NOAA's National Geophysical Data Center (NGDC) website for comparison with H12711. The BAG for survey H12528 was not available for download. As a result, the final bathymetric surface delivered by DEA to AHB was used for the junction comparison with H12711. The 4-meter finalized H12711 surface was compared to each junction survey by generating a difference surface with CARIS Base Editor. At the time of writing, data from H12721 was still being processed. The Descriptive Report for H12721 will include a junction analysis with H12711. H12712 40000 2014 David Evans and Associates, Inc. W Results from the junction analysis are shown in Figure 5. The minimum and maximum differences are associated with sound speed and tide zoning artifacts. Junction results between H12711 and H12712 4-meter bathy grids SupportFiles\H12711_H12712_4m_Junction.png H12720 40000 2014 David Evans and Associates, Inc. S Results from the junction analysis are shown in Figure 6. The minimum and maximum differences are associated with sound speed and tide zoning artifacts. Junction results between H12711 and H12720 4-meter bathy grids SupportFiles\H12711_H12720_4m_Junction.png H12721 40000 2014 David Evans and Associates, Inc. SW The junction analysis between H12711 and H12721 will be included in the H12721 DR. H12528 40000 2013 David Evans and Associates, Inc. NE The H12711 survey area junctions with contemporary survey H12528 in the northeast corner of the survey area. Results from the junction analysis are shown in Figure 7. The minimum and maximum differences, which are located in the vicinity of the shoal at the north end of the Chandeleur Islands, appears to be associated with natural bottom change that has occurred since the junction survey was acquired in 2013. Junction results between H12711 and H12528 4-meter bathy grids SupportFiles/H12711_H12528_4m_Junction.png D00140 20000 2008 Terrasond, Ltd. S The H12711 survey area junctions with prior hydrographic reconnaissance survey D00140. The maximum and minimum reported differences appear to be related to sediment migration since the prior survey with deviations occurring at the edges of sediment waves visible in the H12711 survey data. Results from this analysis are shown in Figure 8. Junction results between H12711 4-meter and D00140 5-meter bathy grids SupportFiles/H12711_D00140_5m_Junction.png 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. None Exist There were no conditions or deficiencies that affected equipment operational effectiveness. Tide Zoning Artifacts The survey area, which lies in the Chandeleur Sound and is protected by the Chandeleur Islands, is 25 to 30 nautical miles from the controlling NWLON (National Water Level Observation Network) station at Pascagoula NOAA Lab. Vertical errors resulting from the limitations of tide zoning are visible in the data. These errors generally range from 10 to 15 centimeters, but in some extreme cases exceed 30 centimeters. This vertical offset is within the typical error contribution of 20 to 45 centimeters for tides and water levels. The largest contributing factor to water level errors in the Chandeleur Sound is meteorological influences which cannot be accounted for by zoning. Recommendations were made in the Descriptive Report for Tidal Zoning submitted with prior survey D00140 that future surveys in this area use a subordinate gauge near the Chandeleur Islands. The hydrographer also recommends that future surveys in this area use water level corrections from local subordinate gauges or rely on ERS methodology for vertical control. Example of tide zoning artifact seen within H12711 SupportFiles/H12711_Tide_Zoning_Error.png 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. Where 200% side scan coverage was required, demonstration of 200% coverage was achieved by producing two separate 100% 1 meter resolution mosaics. 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. Significant side scan sonar contacts were developed with multibeam sonar to obtain a least depth of the contact using multibeam Object Detection coverage requirements. Density The multibeam sonar Set Line Spacing sounding density requirement of 95% of all nodes populated with at least three soundings 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 99.9% of all final CUBE surface nodes contained three or more soundings. Density statistics for all individual item investigation surfaces was reviewed and surpassed the requirement 95% of all nodes populated with at least five soundings.. Data reduction procedures for survey H12711 are detailed in the DAPR. Since submitting the DAPR the S/V Blake’s MRU Alignment values, which are used in TPU computations, have been updated. These values are reported in Table 6 of the DAPR and DAPR Appendix II and have been included in Figure 10 of this report. A summary of the multibeam processing logs is included Separate I Acquisition and Processing Logs of this report. Revised S/V Blake MRU Alignment Values SupportFiles/SV Blake MRU Alignment DAPR revision.png No additional calibration tests were conducted beyond those discussed in the DAPR. Multibeam backscatter was logged in Hypack 7K format and included with the H12711 digital deliverables. Data were processed periodically in CARIS HIPS to evaluate backscatter quality but the processed data is not included with the deliverables. CARIS HIPS 8.1 0 13 2015-06-07 Processing 5.3.2 H12711_MB_4m_MLLW CUBE 4.0 1.96 12.44 NOAA_4m Multibeam sonar Set Line Spacing Coverage H12711_MB_4m_MLLW_Final CUBE 4.0 1.66 12.44 NOAA_4m Finalized Multibeam sonar Set Line Spacing coverage H12711_MB_50cm_MLLW_combined CUBE 50 1.85 10.76 NOAA_0.5m Object Detection Coverage H12711_MB_50cm_MLLW_combined_Final CUBE 50 1.66 10.76 NOAA_0.5m Finalized Object Detection Coverage H12711_100Percent Mosaic 1.0 N/A First 100- percent coverage H12711_200Percent Mosaic 1.0 N/A Second 100- percent coverage Bathymetric grids were created relative to Mean Lower Low Water (MLLW) in CUBE format using Set Line Spacing and Object Detection resolution requirements as described in the HSSD. The 50-centimeter combined surface includes all investigation data at object detection resolution. Field sheets and surfaces were also submitted for all significant individual investigations. The name of the investigation field sheets correspond to the primary side scan sonar contact name. Least depths for all significant contact investigations were added to the final surface with a designated sounding. Additional designated soundings were added to depth surfaces as necessary in order to accurately represent the seafloor in accordance with the NOS HSSD. A complete description of the horizontal and vertical control for survey H12711 can be found in the OPR-J311-KR-14 Horizontal and Vertical Control Report (HVCR), submitted under a separate cover. A summary of horizontal and vertical control for this survey follows. Mean Lower Low Water Pascagoula NOAA Lab, MS 8741533 8741533.tid Verified Observed J311KR2014CORP_rev2.zdf Final North American Datum of 1983 (NAD83) NAD83 UTM Zone 16 North English Turn, LA (293 kHz) Eglin Air Force Base, FL (295 kHz) During survey operations, some Differential Global Positioning System (DGPS) outages from the primary beacon (293 kHz) occurred. The system was manually switched to the secondary beacon (295 kHz) when the primary signal was lost. No data was acquired during DGPS beacon outages. The majority of the chart comparison was performed by comparing H12711 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 RNCs covering the survey area to the corresponding ENCs 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 2015-04-28 2015-05-02 Coastal chart 11363 was compared to US4LA34M within the H12711 survey area. There is a minor inconsistency in the way H12711 Danger to Navigation (DtoN) 3 was applied to the two chart products. The DtoN was applied as a 5-foot sounding on both charts but on the ENC, the sounding is circled by an isolated 6-foot depth contour while on the RNC the 6-foot depth contour running parallel to the shoreline has been bumped out to encompass the 5-foot sounding. No other differences were observed between the charts. 11373 1 80000 52 2015-05 2015-05-01 2015-05-01 Coastal chart 11373 overlaps with US4LA34M and 11363 within the survey area. There are numerous differences between the charts both within and to the north of the H12711 survey area. Chart updates from prior survey H12528 have been applied to 11373, but not 11363, US4LA34M, or US4MS12M. Charts 11363 and US4LA34M depict a platform and a ruined platform along the eastern edge of the survey area near the Chandeleur Islands. The ruined platform is not depicted on chart 11373. No other differences were observed between the charts. US4LA34M 80000 29 2015-01-06 2015-05-11 false In general, surveyed depths are between 0 to 5 feet deeper than charted. Surveyed depths over the shoals at the north end of the Chandeleur Islands are significantly shoaler than charted on US4LA34M. These differences result from the depiction of outdated soundings and contours on US4LA34M. This chart has not yet been updated with results from survey H12528. Depth Difference between H12711 and charts US4LA34M and US4MS12M SupportFiles/H12711_ChartComp_US4.png US4MS12M 80000 22 2014-12-17 2015-05-06 false ENC US5MS12M overlaps with H12711 at the northern end of the survey area. In general, surveyed depths are between 0 to 5 feet deeper than charted. No AWOIS Items were assigned for this survey. No Maritime Boundary Points were assigned for this survey. The Wreck showing Masts PA charted near the north end of the Chandeleur Islands has been disproved by the survey. The survey found an uncharted submerged wreck approximately 120 meters to the north of the disproved wreck. The Wreck PA has been included in the FFF with a description of ‘Delete’. A wreck depicting the surveyed wreck is included in the FFF with a description of ‘New’. The Wreck showing hull or superstructure PA charted near the north end of the Chandeleur Islands has been disproved by the survey. The survey found an uncharted submerged wreck approximately 500 meters to the west of the disproved wreck. This item was submitted as H12711 DtoN 01. The Wreck PA has been included in the FFF with a description of ‘Delete’. A wreck depicting the surveyed wreck is included in the FFF with a description of ‘New’. The Pipe PA charted along the eastern side of the survey area has been disproved by the survey. The feature has been included in the Final Feature File (FFF) with a description of ‘Delete’. All uncharted features are portrayed in the FFF as surveyed and attributed with the description of ‘New’. 3 Three Dangers to Navigation (DtoNs) were submitted for this survey. All DtoNs were added to the charts using preliminary survey data, including the use of predicted tides. A shoal depicted by the 12-foot and 18-foot contours is charted seaward of the Chandeleur Islands. This shoal is accurately depicted on RNC 11373 which has been updated to include the results of prior survey H12528. When compared to RNC 11363 and ENCs US4LA34M and US4MS12M the shoal has accreted westward into Chandeleur Sound. The H12711 survey area does not contain any anchorage areas, maintained navigation channels or channel lines. Seven bottom samples were acquired on April 7, 2015 (DN097) and April 8, 2015 (DN098). The sampling plan followed suggested sample locations included in the PRF provided by the Hydrographic Surveys Division. A shoreline investigation was not performed for this survey. The OPR-J311-KR-14 Project Instructions required a limited shoreline verification but the shoreline of the Chandeleur Islands lies more than one nautical mile to the east of the 4-meter inshore limit in waters too shallow and hazardous for safe navigation of the survey vessel. Other than the previously mentioned junction analysis no other comparisons with prior surveys were conducted. No Aids to Navigation (AtoNs) were charted or located within the H12711 survey area. There were no overhead bridges, cables, or other structures which would impact overhead clearance in the survey area. No submarine cables, submarine pipelines, or tunnels were charted or located within the H12711 survey area. There were no ferry routes or terminals within the survey area. Two platforms are charted along the eastern edge of the survey area near the Chandeleur Islands. Charts 11363 and US4LA34M depict a platform and a ruined platform along the eastern edge of the survey area near the Chandeleur Islands. The ruined platform, which is not included on Chart 11373, has been disproved by the survey. This feature has been included in the FFF with a description of ‘Delete’. The platform was surveyed approximately 100 meters to the north of its charted positon. The charted platform has been included in the FFF with a description of ‘Delete’. A feature depicting the platform in its surveyed position is included in the FFF with a description of ‘New’. Refraction artifacts were visible in the side scan and multibeam data acquired along the Northern Chandeleur Islands. These artifacts appear to have resulted from flood events on the Mississippi and Pearl Rivers which released fresh water into Chandeleur Sound. Evidence of this issue was apparent in the sound speed profiles collected during acquisition. This issue did not cause the H12711 survey data to exceed specification. There were no unusual submarine features or anomalous tidal or environmental conditions observed during the survey that impacted the quality of the survey or worthy of charting. No construction or dredging activities were observed during survey operations. The hydrographer recommends that future surveys in Chandeleur Sound extend to the 2-meter contour. Vessels transiting through Chandeleur Sound do so in waters shallower than this survey’s inshore depth limit. 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 2015-07-07 Jason Creech, CH NSPS/THSOA Certified Hydrographer, Lead Hydrographer 2015-07-07 Data Acquisition and Processing Report 2015-04-24