2019-09-26Jonathan L. Dasler, PE, PLS, CHNSPS/THSOA Certified Hydrographer, Chief of Party2019-09-26Jason Creech, CHNSPS/THSOA Certified Hydrographer, Charting Manager / Project Manager2019-09-26Callan McGriff, EITIHO Cat-A Hydrographer, Lead Hydrographer2019-09-26David T. Moehl, PLS, CHNSPS/THSOA Certified Hydrographer, Lead HydrographerThe survey data meets or exceeds requirements as set forth in the NOS Hydrographic Surveys Specifications and Deliverables, Field Procedures Manual, and Letter Instructions. These data are adequate to supersede charted data in their common areas. This survey is complete and no additional work is required.All field sheets, this Descriptive Report, and all accompanying records and data are approved, with the exception of the deficiencies outlined in this report. All records are forwarded for final review and processing to the Processing Branch.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.Data Acquisition and Processing Report2019-09-19Coast Pilot Report2019-07-11A total of 233 soundings in H13212 were designated in bathymetric data: 226 to facilitate feature management for inclusion in the H13212 Final Feature File (FFF), and seven to override the gridded surface model.Designated SoundingsDuring processing of S/V Blake HDCS lines, navigation information was imported from POS M/V .000 files while importing delayed heave, motion and associated RMS values. This navigation source, Applanix.ApplanixGroup1, is automatically applied at merge when it exists. However, when a CARIS project file is rebuilt, CARIS will report that the navigation source is the HDCSNav. This is a display issue only and does not change the navigation source. This is not an issue for data collected by the RHIB Sigsbee, which relies on HDCS navigation, and does not apply logged navigation, motion and RMS. Additionally, when a line is renamed, such as with the suffix _XL, the HDCS Nav source disappears from the metadata display. Again, this appears to be a display issue only and does not change any navigation sources.CARIS HDCS Navigation SourcesA vessel based laser scanner was used to acquire lidar data along the survey area’s shoreline in order to facilitate the survey, management, and reporting of shoreline and nearshore features. Processed LAS data from the laser scanner are included with the survey deliverables in the Processed directory. Photos were captured during hydrographic operations to aid in the interpretation of the lidar data during processing, for inclusion in the FFF by using the images attribute, and for reporting purposes. Mobile Laser Scanner DataA detailed listing of all data processing software, including software used to process the mobile lidar data, is included in the DAPR.NOAA Profile Version 5.7HIPS/SIPSCARIS10.4.5Grids were originally submitted by the field unit as 50 cm, 1m and 4m finalized single resolution grids and were accepted by the Branch as meeting specifications during the H13212 RSA. After additional review during the SAR, it was found some grids required additional re-computation and re-finalization due to minor revisions of the sounding data and FFF. It was agreed amongst both PHB and AHB to modify the final grid products from single resolution to variable resolution (VR) grids following the NOAA object detection depth based (ranges) estimation method parameters. The effect was improved grid management reducing the number of total number grids from eight (8) to two (2). Given final products are now submitted as VR, no final combined surface is included with this submission.Bathymetric grids were created relative to MLLW in CUBE format using Object Detection resolution requirements as described in the HSSD.H13212_MB_50cm_MLLW0.5CARIS Raster Surface (CUBE)Object Detection24.5580.155NOAA_0.5mH13212_MB_1m_MLLW1CARIS Raster Surface (CUBE)Object Detection24.5530.433NOAA_1mH13212_MB_50cm_MLLW_Final0.5CARIS Raster Surface (CUBE)Object Detection20.0000.155NOAA_0.5mH13212_MB_1m_MLLW_Final1CARIS Raster Surface (CUBE)Object Detection24.55318.000NOAA_1mThe OPR-J347-KR-18 Data Acquisition and Processing Report (DAPR), previously submitted with survey H13195, 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.MBESSeaBat T50-RTeledyne RESONMBESSeaBat T50-PTeledyne RESONLidar SystemLMS-Z390iRIEGLPositioning and Attitude SystemPOS MV 320 v5ApplanixPositioning and Attitude SystemHydrinsiXbluePositioning SystemSPS851TrimblePositioning SystemSPS855TrimblePositioning SystemRTK Bridge-XIntuicomPositioning SystemSPS851TrimbleSound Speed SystemMVP30-350AML OceanographicSound Speed SystemMicro SVP&TAML OceanographicSound Speed SystemSmartXAML OceanographicSound Speed SystemBaseXAML OceanographicSound Speed SystemMicroX SVAML OceanographicConductivity, Temperature, and Depth SensorSBE 19plusSea-Bird ScientificPositioning SystemNetR5Trimble834.5S/V Blake181.0RHIB SigsbeeSupportFiles\OPR-J347-KR-18_Blake.pngS/V BlakeSupportFiles\OPR-J347-KR-18_Sigsbee.pngRHIB SigsbeeAll sounding systems were calibrated as detailed in the DAPR.All data reduction procedures conform to those detailed in the DAPR.Multibeam backscatter was logged in Hypack 7k format and included with the H13212 digital deliverables. Data were processed periodically in CARIS HIPS to evaluate backscatter quality, but the processed data is not included with the deliverables. For dual-head MBES data on S/V Blake, individual 7k files were logged for each sonar head in order to better facilitate additional changes required between systems. 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.Backscatter processing to be performed at the Branch deviates from the current OCS Backscatter Processing SOP dated 02/21/2020. Specifically, for the dual-head sonar configuration used in this survey, the processed depth files in the HDCS survey lines contain combined bathymetric data from both sonar heads. However, due to software limitations, the resulting GSF format data files and backscatter mosaic are based on time series data in .7k files (snippets data) from one individual sonar head, paired with the dual-head sounding data. This is represented in the backscatter mosaic with the vessel name BlakeDHS or BlakeDHP, indicating one set of .7k files from the starboard or port head, respective of the dual-head system was paired with the combined-head HDCS. The naming convention for the MBAB mosaic is H13212_MBAB_2m_BlakeDHS_350kHz_1of2.tiff (DHS for the starboard head of a dual head configuration). This product is the best available from the files associated with this particular dual-head sonar configuration and combined-head acquisition process.An AML Oceanographic Moving Vessel Profiler (MVP) and an AML SmartX or BaseX were the primary instruments used to acquire sound speed readings during multibeam operations for the S/V Blake and the RHIB Sigsbee, respectively. Additional discussion of sound speed methods can be found in the DAPR. For the majority of H13212 survey operations, sound speed was well mixed and varied negligibly, both temporally and spatially. Due to the consistent sound speed profile encountered in this reach of the river, sound speed profiles were measured at approximately one to two-hour intervals during survey operations. Sound speed readings were applied in CARIS at an approximate interval of four hours based on consistent profiles observed throughout the day of survey. Field hydrographers noticed that as hydrographic operations approached the Gulf of Mexico, a salt water influx was present. Due to the variation in sound speed measurements near the mouth of the Mississippi River, cast frequency was increased to 15-minute intervals. Sound speed readings for these days were applied in CARIS at approximately a one-hour time interval based on capturing the most representative sound speed for the day of survey. To visualize this variability, two days of sound speed measurements from S/V Blake are shown in Figure 16, some of these show a change greater than 50 meters per second. Days that were impacted with refraction artifacts and have more frequent sound speed measurements applied to address the variability are listed as follows: S/V Blake DN110 – all lines have SV applied nearest in distance within 1 hour S/V Blake DN111 – all lines have SV applied nearest in distance within 1 hour S/V Blake DN113 – all lines have SV applied nearest in distance within 1 hour RHIB Sigsbee DN113 – lines 1725 through 1751 have SV applied nearest in distance within 1 hour S/V Blake DN118 – all lines have SV applied nearest in distance within 1 hour Even with the increased sound speed sampling acquisition, sound speed effects of varying magnitudes are present in the delivered HDCS data. The mouth of the third largest drainage of the world is a difficult environment to capture all sound speed variabilities present throughout the watercolumn. All sound speed measurements were made within 250 meters of the planned survey boundary. In general, a sound speed measurement was made immediately preceding bathymetric operations, per HSSD. Occasionally a sound velocity profile was taken before survey operations and then rejected during data QC, or taken shortly after the start of acquisition. Figure 17 details all instances when there was a deviation from the HSSD for H13212. Approximately four-hour intervalsSupportFiles\H13212_SV_Cast_Variability.pngComparison graphs showing sound speed variability of two days while surveying the mouth of Southwest PassSupportFiles\H13212_SV_Cast_Query.pngSound speed measurement exceeding start of operations specificationSurvey speeds were typically maintained to meet or exceed along-track density requirements. However, due to swift current pushing the vessel downriver and the need to maintain maneuverability, combined with deep areas requiring expansion of the sonar range and thereby slowing the sonar ping rate, along-track low-density areas are occasionally present in the final data. These typically are narrow swaths centered along nadir and do not impact meeting density requirements for 95% of all nodes. Mobile lidar coverage was obtained on the full extents of both river banks spanning the survey area.Sediment migration on the river bottom was evident throughout the course of this survey. Crosslines and fill lines that were run hours after mainscheme acquisition still exceeded the allowable vertical uncertainty in some areas. Following guidance from HSD OPS and the Atlantic Hydrographic Branch, the hydrographer allowed the CUBE algorithm to estimate a gridded depth in these areas without manual cleaning of the sounding data. The submitted surface has numerous artifacts resulting from these areas of disagreement. When reviewed, soundings deemed as fliers were still rejected. It is the hydrographer's belief that the submitted depths are accurate at the time of the survey. An example of approximately 4-meter horizontal disagreement for H13212 submitted surfaces is shown in Figure 14. Some areas of the greatest disagreement have been noted in the H13212_Notes_for_Reviewer.hob file with the SNDWAV area feature class, submitted in Appendix II Supplemental Survey Records of this report. This is not an exhaustive list of areas, but should detail those that show the major surface artifacts resulting from sediment migration. In the vicinity of Baton Rouge, while in an area of significant sediment migration but prior to flood levels, a field test was conducted to attempt to quantify the amount of change the river bottom experienced at that time of survey. The same line was run upstream at similar speeds with time elapsing between subsequent passes. A subset of the results is shown in Figure 15. A high vertical exaggeration is used in Figure 15 to highlight the magnitude of the sediment migration. The hydrographer's best estimate for this test is that the smaller waves on top are migrating at nearly 1 meter per hour while the larger waves, nearly 2 meters high, are migrating at 5 meters per day.Sediment MigrationSupportFiles\H13212_Sediment_Migration.pngExample of artifacts caused by sediment migration during H13212 operationsSupportFiles\OPR-J347-KR-18_Sediment_Migration.pngAlong-track subset view of field test, prior to flood levels, portraying river bottom changes due to sediment migration5000David Evans & Associates, Inc.2018NH13196At the time of writing, data from survey H13196 was still being processed. The Descriptive Report for H13196 will include the junction analysis with H13212. 40000Oceaneering2014SH12634Survey H12634 was previously conducted by Oceaneering in 2014. The mean difference between H13212 and H12634 survey depths is 21 centimeters (H13212 shoaler than H12634), shown in Figure 9. The surveys agree well, with the major differences representative of surveys impacted by recent dredging activity of Southwest Pass. Figure 10 shows the area of overlap with grey shades showing general agreement. Warmer colors in Figure 10 represent H13212 survey depths shoaler than H12634, while cooler colors indicate H13212 survey depths deeper than H12634. The largest differences appear to be outside the H13212 survey area and associated with the channel and dredging for the Southwest Pass entrance as well as the dump site for said dredging material.SupportFiles\H13212_1m-H12634_4m_depth_delta.pngDistribution summary plot of survey H13212 1-meter vs H12634 4-meterSupportFiles\H13212_vs_H12634_Difference_Surface.pngJunction difference surface between surveys H13212 and H12634Survey H13212 junctions with current survey H13196 and prior survey H12634. Multibeam crosslines were run across the entire survey area 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, fill, and investigation data for the entire survey area. The QC Report tabular output and plots for both survey vessels are included in Separate II Checkpoint Summary and Crossline Comparison. For the S/V Blake the output and plot contain data from a dual-head system, beams 1-256 are from the starboard head while 257-512 are from the port head. Due to significant sediment migration occurring within the survey, crosslines were generally conducted on the same day (occasionally next day) as mainscheme acquisition in order to reduce the impact of the changing riverbed on crossline agreement. This resulted in a typical time differential of less than ten hours, but did not exceed 24 hours, between mainscheme and crossline acquisition and significant change in the riverbed was still apparent. Tests run prior to the 2019 flooding event, which was in full swing during this survey, showed sediment wave movement at a rate of 0.25 meters per hour with even higher rates observed during flooding. Even with these operational adjustments, crossline statistics from the S/V Blake, which operated in deeper water over the main channel, just meet International Hydrographic Organization (IHO) Order 1 specification as reported by the CARIS HIPS QC Report tool. DEA performed an additional crossline analysis using the NOAA Pydro Compare Grids tool to analyze the differences between gridded mainscheme depths and gridded crossline depths. Input grids were 1-meter resolution CUBE surfaces of mainscheme and crossline depths. Results from the crossline to mainscheme difference analysis are depicted in Figure 5. Figure 6 depicts a difference surface portraying the sediment migration seen throughout the duration of survey. This figure details crosslines conducted the next survey day, approximately 24 hours after the first mainscheme line was acquired. Change is significant in the sediment wave field with horizontal migration of up to 15 meters occurring between mainscheme and crossline acquisition. The shape of the waves is apparent in both the crossline/mainscheme difference image and the final multibeam hillshade. In the crossline difference image, overlayed on the final multibeam hillshade, shades of yellow and red indicate shoaling and shades of blue indicate deepening with both following the form of the wave field as sediment waves migrate. Shades of grey indicate areas that meet requirements and are generally outside the sediment wave field where there has been less change. DEA remains confident that data consistency was maintained during acquisition based on swath to swath comparison of two vessel platforms and three sonars operating simultaneously in the same survey area. DEA confirmed that a systematic error, such as positioning or sound speed measurements, was not a factor leading to these large differences based on weekly system comparisons detailed in Separate I Acquisition and Processing Logs of this report. To further document the system performance, an additional crossline report was run on data acquired in the vicinity of Gulfport Channel, near the project’s mobilization grounds and outside of the influence of sediment migration. The output of this report confirms the S/V Blake’s sonar and acquisition and processing procedures are capable of acquiring data that exceeds IHO specification for Order 1 and Special Order as reported by the HIPS QC Report tool. Output from the report is included in Separate II Checkpoint Summary & Crossline Comparisons. This issue was not limited to this survey area; sediment migration affected the entire OPR-J347-KR-18 project area. Impacts of sediment migration are further discussed in section B.2.6 of this report.SupportFiles\H13212_XL-MS_depth_delta.pngH13212 Crossline Difference Distribution Summary PlotSupportFiles\H13212_Crossline_Difference_Surface.pngH13212 crossline difference surface overlayed on the multibeam hillshade highlighting sediment migrationQuality 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.The sounding density requirement of 95% of all nodes, populated with at least five soundings per node, was verified by analyzing the density layer of each finalized surface. Individual surface results are stated in Figures 18 and 19. DensitySupportFiles\H13212_MB_50cm_MLLW_Final.QAv5.density.pngNode density statistics - 50cm finalizedSupportFiles\H13212_MB_1m_MLLW_Final.QAv5.density.pngNode density statistics - 1m finalizedOccasional data gaps in the final Object Detection surfaces exist due to operational restrictions at time of survey. These data gaps were further analyzed after acquisition and determined to be unattainable due to safety or other factors impacting vessel operations. Significant effort was expended during survey operations to maximize object detection coverage in these areas. Some of the sources for these data gaps include: - Holidays or 2-meter coverage gaps behind piers or other baring structures where field unit was physically unable to operate, or safety concerns limited their ability. - Holidays beyond the 2-meter curve (NALL) which were not further investigated due to safety concerns in shallow water. - Holidays or 2-meter coverage gaps near training walls extending into shallow waters. - Holidays beneath baring structures that met the area requirement were rejected in the survey data for final delivery. - Any 2-meter coverage gaps that were previously met prior to final separation model adjustment further discussed in section C.3.3 of this report. Holidays that exist in the final surfaces have been noted in the H13212_Notes_for_Reviewer.hob with the cvrage area feature class, submitted in Appendix II, and attributed with remarks stating the contributing factor leading to the data gap. Areas where the 2-meter curve was not met are included in the H13212_Notes_for_Reviewer.hob with SLCONS feature class and attributed with remarks stating the contributing factor for this deficiency.Data gaps in bathymetric coverage0.030ERS via VDATUM0.0840.5S/V Blake1.01.00.5RHIB SigsbeeAdditional discussion of these parameters is included in the DAPR. Sound speed profiles collected from the RHIB Sigsbee were acquired with AML BaseX or AML SmartX sound speed sensors. The measurement uncertainty for these sensors is listed in the CTD column in Table 8. 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 great than the TPU. To determine if the surface grid nodes met 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 total vertical uncertainty (TVU) at each node. Values greater than 100% indicate nodes exceeding the allowable IHO uncertainty. The resulting calculated TVU values of all nodes in the submitted finalized surfaces are shown in Figures 7 and 8. The finalized surfaces include occasional large vertical uncertainties which exceed IHO Order 1 allowances. These high uncertainties were caused by introducing areas of high depth standard deviation associated with steep slopes when finalizing surfaces with the greater of the two option; and incorporating erroneous real-time sonar uncertainty values during TPU computation. On occasion, the real-time uncertainty logged during acquisition included a sounding with an extremely high depth uncertainty which was well outside of realistic values. During processing, an IHO filter was applied to all sounding data, which rejected soundings exceeding IHO Order 1 thresholds for TVU. These rejected soundings have at times been reaccepted after thorough review by the hydrographer. This issue appears to have been caused by an unresolved software bug in either the sonar top side unit or acquisition system impacting the reported uncertainty, but not the actual depth.SupportFiles\H13212_MB_50cm_MLLW_Final.QAv5.tvu_qc.pngNode TVU statistics - 50cm finalizedSupportFiles\H13212_MB_1m_MLLW_Final.QAv5.tvu_qc.pngNode TVU statistics - 1m finalizedHigh frequency artifacts are visible periodically in the data collected with the dual-head system on the S/V Blake. Despite extensive testing and troubleshooting of mount stability under a range of vessel motion dynamics and speed, applied offsets, and application of patch tests bias, no single source of the artifact could be identified. The high frequency artifact was transient and unrelated to vessel dynamics and loading on sonar mounts at different speeds and induced rolling during testing and is periodically present in both sonars, with a higher magnitude observed on the port sonar. From the findings of the troubleshooting, it is the hydrographer's belief that this is not related to mount instability relative to the IMU of patch test bias values applied and may be related to minor transient timing issues in the dual head system relative to the application of motion data (primarily role). Under this assumption, the further away the sensor is from the ship reference point, the great the magnitude of the error. In this case, while the artifact negatively affects the aesthetic of the final surface deliverable, it is well within IHO specifications for this survey. Figures 11 and 12, display the transient artifact for the dual-head operations. High Frequency artifact in dual-head MBES systemSupportFiles\OPR-J347-KR-18_artifact_port_sonar.pngExample of high frequency artifact shown in surface and along track subset. Subsets of differing magnitudes between separate sonar heads of dual-head system shown on port side of swath (starboard beams shown in red, port beams in green)SupportFiles\OPR-J347-KR-18_artifact_stbd_sonar.pngExample of high frequency artifact shown in surface and along track subset. Subsets of differing magnitudes between separate sonar heads of dual-head system shown on starboard side of swath (starboard beams shown in red, port beams in green)During survey acquisition, it was apparent that the combination of shallow water and the river bottom type (an assumption of soft silty mud) made it difficult to get a clean bottom track return from the MBES system. This most frequently was displayed in shallow, flat areas out of the main channel current. To try to mitigate the effect, sonar settings were changed by the hydrographer during acquisition, including changing power, gain, time variable gain (TVG) settings, and pulse length. In the end no clear solution fixed the issue and the hydrographer continuously tuned the sonar for the best return at the time. This is likely a limitation of the instrument and the acoustic properties of the sediments in the depths being surveyed. The HDCS dataset was well cleaned to mitigate the effects to the final surfaces. However, artifacts within IHO specifications, will be apparent in the final delivered surface as shown in Figure 13.Bottom tracking in shallow waterSupportFiles\H13212_BottomTrackArtifact.pngExample of erroneous bottom tracking of flat shoal areas in HDCS data and resultant surface artifact (gray soundings rejected manually by hydrographer to limit effects to the surface)Delayed heave was applied to data collected by the S/V Blake using the POS M/V .000 file logged during acquisition. This file is loaded using the CARIS Import Auxiliary Data tool. Delayed heave is chosen during the SVC and Merge processing steps. Delayed heave was applied to data collected by the RHIB Sigsbee using the IXSEA Output_E.log file logged during acquisition. This file is formatted similarly to the POS M/V .000 file for delayed heave, but does not contain any position, motion, or associated RMS values. The Output_E.log file was loaded using the CARIS Import Auxiliary Data tool and applied during the SVC and Merge processing steps. The following lines are submitted with real-time heave due to logging errors during acquisition that resulted in no delayed heave file being logged: 2019SI0612122 2019SI0641912 2019SI0641921Delayed HeaveThe S/V Blake acquisition configuration setup for data collected on April 28, 2019 (DN118) was in error. Instead of logging the starboard sonar with beams 1-256 and the port sonar with beams 257-512; the setup was configured to log the port sonar twice, with beams 1-256 and 257-512. To account for this error all erroneous 1-256 beams were rejected using a swath filter and only data collected from the appropriate sonar are accepted. As this data was fill and investigation data, no data gaps were generated as a result of rejecting one sonar head.Dual-head configuration setup errorThe chart comparison was performed by comparing H13212 survey depths to a digital surface generated from electronic navigational charts (ENCs) covering the survey area. A 10-meter product surface was generated from a triangular irregular network (TIN) created from the ENC’s soundings, depth contours, and depth features. An additional 10-meter HIPS product surface of the entire survey area was generated from the 4-meter CUBE surface. The chart comparison was conducted by creating and reviewing a difference surface using the ENC surface and survey surface as inputs. The chart comparison also included a review of all assigned charted features within the survey area. The results of the comparison are detailed below. Sediment migration and other river environmental conditions contribute to a continually changing river bottom resulting in large differences observed by the field unit daily. 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.ENC US6LA5AM covered the full extents of survey H13212. Large differences exist between the surveyed depths and charted soundings mainly contributed to the continuously changing river environment. Figures 22 through 31 show the magnitude of differences along the comparison area.SupportFiles\H13212_Chart_comp_US6_1.pngDepth difference between H13212 and chart US6LA5AM, area 1 of 10SupportFiles\H13212_Chart_comp_US6_2.pngDepth difference between H13212 and chart US6LA5AM, area 2 of 10SupportFiles\H13212_Chart_comp_US6_3.pngDepth difference between H13212 and chart US6LA5AM, area 3 of 13SupportFiles\H13212_Chart_comp_US6_4.pngDepth difference between H13212 and chart US6LA5AM, area 4 of 10SupportFiles\H13212_Chart_comp_US6_5.pngDepth difference between H13212 and chart US6LA5AM, area 5 of 10SupportFiles\H13212_Chart_comp_US6_6.pngDepth difference between H13212 and chart US6LA5AM, area 6 of 10SupportFiles\H13212_Chart_comp_US6_7.pngDepth difference between H13212 and chart US6LA5AM, area 7 of 10SupportFiles\H13212_Chart_comp_US6_8.pngDepth difference between H13212 and chart US6LA5AM, area 8 of 10SupportFiles\H13212_Chart_comp_US6_9.pngDepth difference between H13212 and chart US6LA5AM, area 9 of 10SupportFiles\H13212_Chart_comp_US6_10.pngDepth difference between H13212 and chart US6LA5AM, area 10 of 102019-07-236US6LA5AM120002018-07-17falseNo DtoNs were submitted for this survey. Potential DtoNs are included as new features in the FFF. Because of the significant change that occurred within the project area since the last survey of the Mississippi River, HSD staff advised DEA to limit reporting of Dangers to Navigation to immediate hazards that could cause loss of life or impact waterborne commerce. All uncharted features discovered during survey acquisition are addressed in the FFF. Refer to the FFF for additional information.Numerous charted features exist within the limits of sheet H13212. All assigned features included in the project CSF have been addressed by the survey and are included in the FFF. Due to the large scale of the survey (1:5,000), many charted features have been recommended for deletion to be replaced by new higher resolution features digitized from the survey data. The hydrographer frequently requested guidance from HSD staff on appropriate depiction and attribution of features when the procedures set in the HSSD were insufficient to support the requirements of this precision navigation survey. Copies of this correspondence are included in Appendix II. The survey area includes numerous charted features labeled as Reported (Rep), Position Approximate (PA), and Position Doubtful (PD). - The Obstruction PD (Position Doubtful) with least depth unknown charted along the western edge of the Southwest Pass Channel at mile 1.6 BHOP (Below Head of Passes) was disproved by the survey. - The Pile PA (Position Approximate) charted along the eastern edge of the Southwest Pass Channel at mile 4.9 BHOP was disproved by the survey. - The Pile PA charted east of the Southwest Pass Channel at mile 9.2 BHOP was disproved by the survey. - The Obstruction PA with depth unknown charted in the vicinity of Southwest Pass Light 10 at mile 14.2 BHOP was disproved by the survey. A new submerged obstruction was surveyed 21 meters northwest of the charted location. - The Pile PA charted south of Southwest Pass Light 10 at mile 14.3 BHOP was disproved by the survey. - The Piles PA charted south of Southwest Pass Light 10 at mile 14.5 BHOP was disproved by the survey. A new submerged pile was surveyed in this position.  - The Pile PA charted east of the Southwest Pass Channel at mile 16.9 BHOP was disproved by the survey. - The Obstruction PA with least depth unknown charted along the western edge of the Southwest Pass Channel at mile 17.4 BHOP was disproved by the survey. - The Obstruction PA with depth unknown charted south of Southwest Pass East Jetty End Light 4 has been disproved by the survey. A new obstruction depicted by an area feature was surveyed at this location. - The 35-foot Obstruction Reported 2008 (exposed pipeline) charted southeast of the Southwest Pass East Jetty End Light 4 was disproved by the survey. All disproved features have been included in the FFF with a description of ‘Delete’. All new features have been included in the FFF depicting the feature as surveyed and with a description of ‘New.’ Multiple training walls were located in the survey area and surveyed with a mix of multibeam and mobile laser scanner coverage. The majority of the training walls were found in a ruined condition during survey operations; often consisting of sections of interspersed baring and submerged piles. HSD staff provided guidance on the desire to depict the pile dikes as a single line feature rather than multiple lines segments with varying water level effect (WATLEV) attribution. Training walls were digitized following the approximate centerline of the ruined section and may deviate from the surveyed location of individual piles. Least depths of submerged portions of training walls were not designated based on this guidance. A copy of this correspondence is included in Appendix II. All training walls are included in the FFF and include image attribution from photos acquired during survey operations.No bottom samples were required for this survey.There are no designated anchorages, traffic separation schemes, or pilot boarding areas within the limits of H13212. The entire extent of H13212 includes and runs along the channel, Southwest Pass, that provides safe transit into the Mississippi River. According to the chart, the controlling depth for the section of the channel is 45 feet. H13212 also includes the northern portion of South Pass, as it approaches Head of Passes, that has a controlling depth of 17 feet. H13212 has multiple areas, mainly encroachment of the shoulders on the cut bank, that are shoaler than the controlling depth. The controlling depths for both channels were included in the chart comparison images contained in section D.1.1 of this report. Warm colors in the channels, representing H13212 surveyed soundings shoaler than controlling depths, can be seen encroaching into the channel on Figures 22, 23, 25, 26, and 31. A Safety Fairway junctions the south entrance of the survey area with charted Safety Fairway 166.200. The safety fairway was outside of the survey area and was not investigated during survey operations. There are ten range lines within the survey limits. Range markers were positioned using vessel based lidar surveying techniques and are included in the FFF.No Maritime Boundary Points were assigned for this survey.No ferry routes or ferry terminals exist for this survey.All submarine features were investigated entirely using object detection MBES coverage. There are nine cable and pipeline areas charted in the survey extents of H13212, where anchoring, trawling, and dragging are restricted. These precautionary areas were surveyed using object detection MBES coverage techniques and carefully reviewed for any pipelines or cables that were exposed and pose a risk to navigation. Survey H13212 has three charted pipelines, attributed as retain in the FFF, and 38 new pipeline sections included in the FFF. All pipelines located within the survey limits were submitted to the Bureau of Safety and Environmental Enforcement (BSEE). A pipeline report included in Appendix II, was submitted to the BSEE on August 21, 2019, reporting sections of exposed or unburied pipeline visible in the MBES data. The report indicates the positions of the start and end points of sections of what appear to be exposed pipelines based on interpretation of multibeam data. It is possible that some of the reported items include submerged outfalls and other linear features with a signature of a pipeline that are not associated with oil and gas infrastructure. Due to the inability to accurately depict the location and orientation of all exposed pipelines with a single line segment, these features have been included in the FFF should further action be required after survey submittal. It is not the hydrographer’s intention that these pipeline features be used as source information for charting without further validation of origin.No new insets are recommended for this area.Aids to Navigation (AtoN) were investigated using mobile lidar and visual observations. AtoNs that were missing, damaged, or not serving their intended purpose were reported to the USCG via email on August 23, 2019. Due to the large number of AtoNs requiring reporting, email was used for reporting instead of using the USCG Navigation Center’s Online ATON Discrepancy Report as specified in the HSSD. This method was approved by the HSD Project Manager for this hydrographic survey. A copy of the email submittal is included in Appendix II. AtoNs have been included in the sheet’s FFF with appropriate comments and recommendations. The Southwest Pass Head West Range Rear Light, which was included in the CSF as an unassigned feature, was visible in the mobile laser scanner data collected during survey operations. The aid was confirmed to be on station and serving its intended purpose and has been included in the FFF with a description of 'Retain'.No overhead features exist for this survey.The hydrographer recommends that this area be resurveyed regularly due to the significant change in depths from sediment migration and dredging activity observed over the project timeline.Large and quickly moving sediment waves from sediment migration were observed during acquisition. Refer to section B.2.6 of this report for additional information. Large sound speed changes were present during survey operations near the mouth of Southwest Pass. This area where the freshwater from the river mixed with the saltwater from the gulf showed changes in the watercolumn exceeding 50 m/s. Refer to section B.2.7 of this report for additional information.Shoreline investigations were completed using lidar survey techniques. Refer to the DAPR for additional information regarding the acquisition and processing of these data. All new and assigned features have been included in the sheet’s FFF with appropriate comments and recommendations.No platforms exist for this survey.Construction of shoreline features was ongoing during survey operations. This mainly included the building of new shoreline stabilization using boulders placed by cranes. Barges containing boulders and cranes are shown in lidar data. This work was ongoing after survey operations concluded, therefore SLCONS and other shoreline features contained in the FFF may be outdated. Figure 32 shows an example of these ongoing construction operations. The USACE Mississippi Valley Division, New Orleans District (MVN) had numerous dredging projects during the time of survey operations in H13212 to address the active shoaling in Southwest Pass deposited by long-term high river stages during historic flooding. Bathymetric data was collected before, during, and after dredging activities; resulting in large disagreements of river bottom locations and artifacts in the surface. In addition, dredging operations typically created an extremely turbid water column with suspended sediment that lowered the efficiency of the MBES returns. The areas of active dredging were surveyed using object detection MBES coverage techniques and carefully reviewed. Dredging areas that created disagreement in the MBES surface were documented in the H13212_Notes_for_Reviewers.hob file with the DRGARE area feature class, submitted in Appendix II of this report. The following dredging activities were observed during survey operations on this sheet: - The hopper dredge, Glenn Edwards, was observed actively dredging at Head of Passes to approximately 1 mile BHOP on February 27, 2019. - The cutter dredge, Captain Frank, was observed actively dredging from approximate miles 4-5 BHOP on April 29, 2019. - The cutter dredge, R.S. Weeks, was observed actively dredging from approximate miles 5-7 BHOP on March 13, 2019. - The hopper dredge, Bayport, was observed actively dredging from approximate miles 8-9 BHOP on April 13, 2019. - The hopper dredge, Stuyvesant, was observed actively dredging from approximate miles 15-17 BHOP on April 20, 2019 and again on April 28, 2019.SupportFiles\H13212_Construction.pngOngoing construction observed during H13212 survey operationsAny revisions to the Descriptive Report (DR) applied during office processing are shown in red italic text. The DR is maintained as a field unit product, therefore all information and recommendations within this report are considered preliminary unless otherwise noted. The final disposition of survey data is represented in the NOAA nautical chart products. All pertinent records for this survey are archived at the National Centers for Environmental Information (NCEI) and can be retrieved via https://www.ncei.noaa.gov/. Products created during office processing were generated in NAD83 UTM 16N, MLLW. All references to other horizontal or vertical datums in this report are applicable to the processed hydrographic data provided by the field unit.Navigable Areameters2019-08-082018UTCAtlantic Hydrographic Branch2019-04-292019-02-11Jonathan L. Dasler, PE, PLS, CHMultibeam Echo Sounder BackscatterMultibeam Echo SounderContractorMississippi River, Southwest PassH132125000United States10LouisianaDavid Evans and AssociatesMississippi RiverMississippi RiverOPR-J347-KR-18A complete description of the horizontal and vertical control for survey H13212 can be found in the OP-J347-KR-18 Horizontal and Vertical Control Report (HVCR), to be submitted with the final survey for this project. A summary of horizontal and vertical control for this survey follows.Projected UTM 16During acquisition, RTK correctors were obtained from Louisiana State University’s (LSU) Center for Geoinformatics (C4G) service via a dedicated cellular modem in the extents of cellular coverage. The southern end of survey H13212 was outside of cellular coverage. In this area a RTK GNSS base station was installed at the NOAA Center for Operational Products and Services (CO-OPS) water level station at Pilot Station East in Southwest Pass. These correctors provided RTK level of accuracy for horizontal and vertical positions for all survey data. If a loss of service was experienced during acquisition it was noted by the field watch stander, and those data were further analyzed to be resurveyed. No prolonged outages were experienced while surveying on the network of H13212. Verification of the C4G network correctors were conducted by the field unit at various monuments established by USACE along the shoreline of the OPR-J347-KR-18 project area. The base station was positioned using the National Geodetic Survey (NGS) Online Positioning User Service (OPUS) and compared to an RTK position obtained from the C4G network. Methods, analysis and results of position checks are further documented in the project wide HVCR.North American Datum 1983LSU's C4G provided RTK corrections for the northern half of H13212. The cutoff line was a perpendicular line to Southwest Pass approximately 8.5 miles Below Head of Passes (BHOP), as shown in Figure 20. The C4G network's most southeast base station, BVHS, is located in Boothville, LA approximately 30 km to the northwest of this line. Due to the distance of this survey from the reference stations used in LSU’s C4G network, DEA installed a base station (BASE) at the Southwest Pass Pilot Station to provide an additional source of RTK corrections. This station was utilized for all multibeam survey data collected downriver of mile 8.5 BHOP. The base station installation and use followed practices specified in the HSSD and was routinely verified by the field unit by conducting periodic position checks. This was a temporary setup and no permanent survey marker was occupied or established. Figure 21 shows details of this setup location. Methods, analysis and results of these monument and base station check-ins are further documented in the project wide HVCR. RTK corrector sourcesSupportFiles\H13212_RTK_Sources.pngH13212 RTK Corrector SourcesSupportFiles\H13212_BASE_Setup.pngH13212 DEA Installed GNSS Station "BASE"Water level floats were conducted by the field unit at the location of each USACE or NOAA gauge within the OPR-J347-KR-18 project area. Methods, analysis and results of these floats are further documented in the project wide HVCR. In general, these floats helped identify issues between the USACE and NOAA datums and that of the MLLW separation model utilized during acquisition. These tests resulted in iterations to the model by NOAA, discussed in detail in the HVCR. Water Level FloatsAs discussed in section C4 of the DAPR and the project wide HVCR, due to a revision of the separation model used during acquisition, all ERS water levels were reprocessed after the revised model was issued. Refer to section B4.c of the DAPR for an outline of the processing steps.Separation model change and re-processingMean Lower Low WaterNAD83-LWRP2007_RM13.4_MLLW2012-2016_Geoid12B.csarERS via VDATUMWhile ERS via VDATUM is listed in Table 12, it was one of the limited options available in the XML DR schema’s enumerated values. The separation model covering the H13212 survey area was constructed by the HSD Operations Branch specifically for this survey project using NAVD88 (GEOID 2012B) to Mean Lower Low Water (MLLW 2012-2016) values. Refer to the HVCR submitted under separate cover for additional information.28.883888805689.24681629.150975694489.4403176111David Evans and Associates, Inc. (DEA) conducted a hydrographic survey of the assigned area in the Mississippi River. Survey H13212 was conducted in accordance with the November 19, 2018 Statement of Work and Hydrographic Survey Project Instructions dated August 8, 2019. The Hydrographic Survey Project Instructions reference the National Ocean Service (NOS) Hydrographic Surveys Specifications and Deliverables Manual (HSSD) (March, 2018) as the technical requirements for this project.Survey Limits were surveyed in accordance with the requirements in the Project Instructions and the HSSD. SupportFiles\OPR-J347-KR-18_Survey_Outline.pngOPR-J347-KR-18 Survey AreasThe Ports of Southern Mississippi River represent the largest port complex in the world and one of the most heavily trafficked waterways in the United States. Annually, over 500 million tons of cargo is moved on the Lower Mississippi. This project area includes the Port of South Louisiana, the Port of New Orleans, the Port of Greater Baton Rouge, and Plaquemines Port, all ranking in the top 12 ports for annual tonnage in the United States. The Port of South Louisiana, river mile 114.9 to 168.5, is the largest tonnage port in the western hemisphere, handling approximately 262 million tons. The Port of New Orleans, river mile 81.2 to 114.9, handles approximately 90 million tons annually. The Port of Greater Baton Rouge, river mile 168.5 to 253, and Plaquemines Port, river mile 0 to 81.2, handle approximately 73 and 57 million tons annually, respectively.* Critical Charting updates are needed for the Mississippi River, especially for areas outside of the U.S. Army Corps of Engineers (USACE) federally maintained channel areas. These areas outside of the federally maintained channel account for the majority of the navigable river and include ports and terminals essential for commerce and trade. The new bathymetric data in this project area, encompassing 89 SNM, will support high resolution charting products for maritime commerce and update National Ocean Service (NOS) nautical charting products. * U.S. Army Corps of Engineers, Navigation Data Center, Waterborne Commerce Statistics Center, Principal Ports of the United States, www.navigationdatacenter.us/data/datappor.htm77.02847.70034.664.09000077.02260.20018.180000S/V Blake0587.50016.480000RHIB Sigsbee6.7600002019-02-112019-02-122019-02-132019-02-262019-02-272019-03-012019-03-022019-03-042019-03-052019-03-072019-03-082019-03-092019-03-102019-03-112019-03-122019-03-132019-04-132019-04-142019-04-152019-04-162019-04-172019-04-182019-04-192019-04-202019-04-212019-04-222019-04-232019-04-242019-04-252019-04-262019-04-272019-04-282019-04-29SupportFiles\H13212_SurveyOutline.pngH13212 Survey OutlineAll waters in survey areaObject Detection Coverage (HSSD Section 5.2.2.2) Project Instructions called for high resolution charting at 1:5,000 survey scale to support NOAA’s Precision Navigation initiative for the Mississippi River including: Object Detection Coverage for all waters in the survey area to the 2-meter depth contour; Ellipsoid Reference Survey (ERS) using a custom separation model for the Mississippi River; verification of ATONs; assignment of shoreline and nearshore features (including bridges, overhead wires, revetments, assigned existing terminals, and all uncharted features) to be obtained by a vessel based mobile laser scanning technology and imaging system; and delivery of LAS data referenced using ERS methods. Operational challenges included, but were not limited to: conducting surveys in a heavily congested industrial waterway; high river current velocities and transiting debris from high water levels; over 465 miles of shoreline surveys in restricted waters with small launch operations in close proximity to terminals, large barge fleets, wrecks, ruins, submerged piling, and numerous snags; minimal river access for provisioning and refueling; dynamic sediment migration exceeding 0.5 meters per hour in some areas; resolution of chart datum and revisions to the separation model; coordinating mapping efforts with ships at berth; dense fog; on-going dredging operations; and various navigational trials associated with a heavily trafficked industrial waterway. To mitigate these challenges and with the volume of shoreline operations required, survey operations were conducted during daylight hours only, AIS and internet vessel tracking systems were utilized, and continuous communications were made to terminal operators and vessel captains by radio and phone. Object detection coverage was obtained over the survey area in depths greater than 2 meters relative to chart datum using 100% multibeam echosounder (MBES) and backscatter unless otherwise discussed in individual sections of this report. This coverage type follows Option A of the Object Detection Coverage requirement specified in Section 5.2.2 of the 2018 HSSD. Historic flooding of the Mississippi River during OPR-J347-KR-18 survey impacted safe operations in high currents and restricted operations. Many features were in locations that restricted a 90-degree pass due to strong currents and proximity to shoreline or fixed structures. Further, dredging activity, flooding, and strong river currents resulted in significant sediment migration during and between survey operations, evident on this survey sheet. Unavoidable coverage gaps are evident in some areas and are primarily due to training walls that impeded safe vessel operations. Other factors that blocked or impeded safe vessel operations resulting in data gaps included: high river currents, out-flow pipe areas, in-water facilities, and ruins. Significant efforts were expended to maximize coverage to the extent possible in these areas. Section B.2.10 of this report discusses issues restricting this survey coverage in greater detail. Figure 2 depicts the survey outline that was obtained for H13212. The river bottom is continuously changing due to currents, vessel propeller wash, dredging activity, construction and/or other factors present in the river environment. Changes in the river bed were observed during acquisition, primarily due to sediment migration and dredging activity. Section B.2.6 of this report further discusses these issues and impacts to the final deliverable data. In all cases the hydrographer has verified that soundings accurately depicted the river bed at the time of acquisition.The entire survey is adequate to supersede previous data.