OPR-K354-KR-18Louisiana CoastLouisiana CoastOcean Surveys, Inc.H131023Trinity ShoalLouisianaUnited States400002018George G. ReynoldsNavigable Area2018-08-062018-06-142018-09-22Multibeam EchosounderSide Scan SonarMultibeam Echosounder BackscattermetersUniversal Transverse Mercator (UTM)UTCAtlantic Hydrographic BranchThe purpose of this project is to provide contemporary surveys to update National Ocean Service (NOS) nautical charting products. All times are recorded in UTC. Data recorded and presented relative to UTM Zone 15 North. THE INFORMATION PRESENTED IN THIS REPORT AND THE ACCOMPANYING DIGITAL DATA REPRESENTS THE RESULTS OF SURVEYS PERFORMED BY OCEAN SURVEYS, INC. DURING THE PERIOD OF 28 MAY 2018 TO 24 SEPTEMBER 2018 AND CAN ONLY BE CONSIDERED AS INDICATING THE CONDITIONS EXISTING AT THAT TIME. REUSE OF THIS INFORMATION BY CLIENT OR OTHERS BEYOND THE SPECIFIC SCOPE OF WORK FOR WHICH IT WAS ACQUIRED SHALL BE AT THE SOLE RISK OF THE USER AND WITHOUT LIABILITY TO OSI.Any 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 15N, MLLW. All references to other horizontal or vertical datums in this report are applicable to the processed hydrographic data provided by the field unit.ContractorThis survey provides hydrographic data for the Gulf of Mexico waters approaching the Louisiana Coast south of Vermilion Bay. The general locations of the survey limits are presented in Table 1. 29.310797305692.324639111129.135214888992.1161013056Survey limits were acquired in accordance with the requirements in the Project Instructions and the HSSD.As noted in the Hydrographic Title Sheet, the Project Instructions signature date was August 6, 2018. The survey limits were modified from earlier Project Instructions with a signature date of March 23, 2018. The following text is copied verbatim from the latest Project Instructions' Purpose and Location Section. "The Louisiana Coast project will provide contemporary surveys to update National Ocean Service (NOS) nautical charting products. It is in the vicinity of the Atchafalaya River Delta, and Port of Morgan City, Louisiana. The survey will provide updated bathymetry and feature data to address concerns of migrating shoals and exposed hazards, thus reducing the risk to navigation within the project area. The Port of Morgan City is growing significantly and is working on programs to deepen and maintain the ship channel through the Gulf, bay, and up the Atchafalaya River to the Port of Morgan City where it intersects with the Gulf of Mexico Intracoastal Waterway. The Port serves a number of industries, including the offshore oil, chemical and machinery industries, as well as shrimp and other seafood fisheries in the Gulf of Mexico. In addition to the port commerce, the Atchafalaya River delta has a rich ecosystem that supports both commercial fishing and recreational fishing communities. Updated charts from this project will support commerce and protect the environment by improving the safety of navigation for area traffic. The project will cover approximately 300 square nautical miles of high priority survey area identified in the 2016 Hydrographic Health model. Modern surveys show significant shoaling and sediment transport; OPR-K354-KR-17 documented a shoal that had shifted a mile westward since the area was last surveyed in 1935. Adjacent surveys uncovered numerous exposed pipelines and hazards. Data from this project is intended to supersede all prior survey data, updating the local charting products."The entire survey is adequate to supersede previous data.All waters in survey areaComplete coverage (refer to HSSD Section 5.2.2.3). LNM no less than 10,592 LNM. Acquire backscatter data during all multibeam data acquisition (HSSD Section 6.2). Report significant shoaling via weekly progress report. COR may adjust surveying prioritization based on observed shoaling. Survey Coverage is in accordance with the requirements in the Hydrographic Survey Project Instructions and the Statement of Work (August 6, 2018), and the Hydrographic Surveys Specifications and Deliverables, [April, 2017 (HSSD)]. Where required, Complete Coverage was accomplished by acquiring one hundred percent (100%) side scan sonar (SSS) coverage with concurrent multibeam echosounder (MBES) with backscatter or Complete Coverage MBES with backscatter. Additional SSS and MBES coverage was obtained as necessary to fill gaps in coverage, to provide a least depth for all significant SSS contacts, and to disprove charted features. Gaps in the 100% SSS coverage were addressed with SSS fill-in lines or covered with complete MBES data. Bathymetric "sounding stars" were also acquired to verify or disprove charted depths that fell between two MBES survey lines when the charted depth was shallower than the adjacent survey soundings.Survey H13102 MBES coverage overlaid on RNC 11340.file:///N:/Reports/DRs/H13102/H13102_Survey-Coverage.jpgR/V Ocean Explorer0111.390001837.100100.9700111.390001837.100100.9705.2600056.722018-06-142018-06-152018-06-222018-06-232018-06-252018-06-262018-06-272018-06-282018-06-292018-06-302018-07-012018-07-022018-07-032018-07-042018-07-052018-07-062018-07-072018-07-082018-07-092018-07-102018-07-112018-07-122018-07-132018-07-152018-07-192018-07-222018-07-262018-07-272018-07-282018-07-292018-07-302018-07-312018-08-072018-08-082018-08-142018-09-152018-09-162018-09-22The linear nautical miles (LNM) for MBES-only development and fill-in lines were included under the heading "Mainscheme MBES" in Table 3, Hydrographic Survey Statistics. There was no SSS-only mileage for this survey. Refer to the Data Acquisition and Processing Report (DAPR) for a complete description of data acquisition and processing systems, the survey vessel, quality control procedures and data processing methods. Additional information to supplement sounding and survey data, and any deviations from the DAPR are discussed in the following sections.R/V Ocean Explorer182EdgeTech4125SSSTeledyne RESONSeaBat 7125 SV2MBESApplanixPOS MV 320 v5Positioning and Attitude SystemTrimbleProBeaconPositioning SystemTrimbleMS750Positioning SystemTrimbleNetR9Positioning SystemAML OceanographicMicro XSound Speed SystemAML OceanographicBase XSound Speed SystemODIM Brooke OceanMVP30Sound Speed SystemA total of 100.97 nm of crossline data was acquired on June 14-15, July 12, and August 14, 2018 (DNs 165, 166, 193, and 226). In most of the survey area, crosslines were run north-northeast to south-southwest, meeting the east to west mainscheme lines at an angle. After these lines were collected, the sheet was extended to the south. Crosslines in the southern section were run as continuations of the main section's crosslines, and the mainscheme lines were run perpendicular to them in a northwest-southeast orientation (Figure 2). Soundings from mainscheme lines and crosslines were compared periodically throughout survey operations by reviewing preliminary MBES surfaces and using CARIS HIPS Subset Editor. Crossline comparisons provided confirmation that the system offsets and biases were entered correctly and verified the accuracy of sounding correctors (i.e. tide, sound speed, TrueHeave). Statistical quality control information was compiled from a difference surface, generated in CARIS HIPS, between the depth layer of a 1.0m CUBE surface composed only of crossline data and the depth layer of a 1.0m CUBE surface composed only of mainscheme data. The crossline analysis results demonstrate good agreement between crossline soundings and mainscheme soundings. The average depth difference is 0.01m and 99.88% of the 1.0m comparison cells have differences within +/- 0.25m. Figure 3 is a histogram showing the distribution of depth differences for all comparison grid cells considered.An overview of the crossline layout on a 1.0m surface created from mainscheme MBES data and colored by depth. RNC 11349 is visible in the background.file:///N:/Reports/DRs/H13102/H13102_XL_overview.jpgThe graph shows a frequency distribution of the depth differences between the H13102 mainscheme data and the H13102 crossline MBES data. Statistics from the depth difference sample set are displayed above the graph.file:///N:/Reports/DRs/H13102/H13102_XL-Main_Histogram.jpg00.17166ERS via VDATUMR/V Ocean ExplorerN/A12The methods used to minimize the uncertainty in the corrections to echo soundings are described in detail in Section B. Processing and Quality Control of the project DAPR. Survey H13102 did not deviate from the methods documented in the DAPR. The Total Vertical Uncertainty Quality Check (TVU QC) "Ratio Method" was used to evaluate IHO uncertainty for the finalized surface, which was generated using the "greater of the two" option in the CARIS "Finalize Base Surface" utility. The TVU QC "Ratio Method" is described in the Chapter 4 Appendices of the NOAA OCS Field Procedures Manual (FPM) dated April 2014. Per the FPM TVU QC section, "The hydrographer should use the finalized surface because this surface will identify areas where either the uncertainty or the standard deviation exceeded the maximum allowable error and the greater of these two values is used in addition to having the uncertainty scaled to a 95% CI, whereas unfinalized surface uncertainties are reported at the 68% CI." The FPM TVU QC section also states that, "[ratio] values which do not require further examination are from -1 to 0 and the values which do require further examination are from -100 to -1". Results from the TVU QC indicate that 99.99% of the nodes in this surface meet IHO Order 1 uncertainty specifications, i.e. the ratio values of nearly all the nodes are between 0 and -1. Of the 91 million nodes considered, 23 had a ratio value below -1. Upon examination it was found that the nodes with ratio values below -1 were located over known seafloor disturbances and/or known discrete features resulting in higher standard deviation values and finalized uncertainty values, which is to be expected.One (1) prior survey and 2 contemporary surveys junction with Survey H13102. Figure 4 displays the location of the prior and contemporary junction surveys for Project OPR-K354-KR-18. The allowable TVU for the range of water depths within Survey H13102 is 0.50m to 0.53m. Therefore, according to the XMLDR Junction Area "maximum difference" threshold guidance equation (SQRT2 * TVU) the junction discrepancy action threshold equals 0.71m. Survey junctions for Project OPR-K354-KR-18. RNC 11340 is displayed in the background.file:///N:/Reports/DRs/H13102/H13102_Junction_Overview.jpgH13040400002017Ocean Surveys, Inc.NSurvey H13040, a MBES/SSS survey conducted by Ocean Surveys, Inc. in 2017, overlaps the northern border of H13102. Depth data for Survey H13040 were taken from the dataset delivered to NOAA by Ocean Surveys, Inc. on February 6, 2018 in the form of a 1.0m resolution CARIS Spatial Archive (CSAR) raster "H13040_MB_1m_MLLW_Final.csar." To conduct the junction comparison the depths from the H13040 data were subtracted from the depths in the H13102 surface using the CARIS HIPS Difference Surface function. A histogram of the differences is shown in Figure 5. Survey H13040 and Survey H13102 were run with the intention of achieving 100% SSS coverage along the 11,800m border that they share. Each survey's MBES coverage in this area is "skunk stripe" coverage. The mainscheme lines of H13040 are oriented E-W, and while the mainscheme lines of H13102 are also nearly E-W, they are offset at an angle and are not quite parallel to the lines of H13040. The junction area is relatively sparse with small patches of crossline overlap and long stripes of mainscheme data overlap. The extent of mainscheme overlap is approximately 180m while the crosslines overlap by as much as 340m. Overall depths from H13102 show good agreement with depths from the H13040 survey. The average difference between these surveys is 0.07m and 99.38% of the 1.0m comparison cells have differences within +/- 0.25m. The areas of depth differences are spatially variable throughout the junction area. All (100%) junction comparison cells have a difference below the discrepancy action threshold of 0.71m.Surface-to-surface difference histogram comparing Survey H13102 to H13040.file:///N:/Reports/DRs/H13102/H13102_Junction_H13040_Histogram.jpgH13101400002018Ocean Surveys, Inc.WData from contemporary Surveys H13101 and H13102 overlap along a common border of approximately 18,000m. Both surveys were acquired to meet 100% SSS coverage for the majority of the area they cover (approximately 17,650m along the common border), and complete coverage MBES in the southernmost areas of both surveys (approximately 350m along the common border). The mainscheme line plans of the two surveys are parallel and closely (but not completely) aligned. The "skunk stripe" coverage MBES data between the two surveys have a large amount of overlap, producing a relatively dense junction area. The mainscheme lines overlap by as much as 570m. Depths from 1.0m CUBE surfaces compiled from the MBES data from each survey were compared using the CARIS HIPS Difference Surface function. A histogram of the differences is shown in Figure 6. Depths from the two surveys show good agreement with one another. The average difference between these surveys is 0.01m and 99.99% of the 1.0m comparison cells have differences within +/- 0.25m. The differences in depth are spatially variable throughout the junction area. All (100%) junction comparison cells have a difference below the discrepancy action threshold of 0.71m.Surface-to-surface difference histogram comparing Survey H13102 to H13101.file:///N:/Reports/DRs/H13102/H13102_Junction_H13101_Histogram.jpgH13103400002018Ocean Surveys, Inc.EData from contemporary Surveys H13102 and H13103 overlap along a common border of approximately 22,900m. Both surveys were acquired to meet 100% SSS coverage for the majority of the area they cover (approximately 20,400m of the common border), and complete coverage MBES in the southernmost areas of both surveys (approximately 2,500m of the common border). The mainscheme line plans of the two surveys are parallel and closely (but not completely) aligned. The "skunk stripe" coverage MBES data between the two surveys have a large amount of overlap which provides a relatively dense junction area. The mainscheme lines overlap by as much as 590m. The junction area of these two surveys also contains one MBES line that was run across both survey sheets over an intermittently exposed pipeline for approximately 1285m. Approximately 21m of this exposed pipe is in the southern end of Survey H13103; the remainder is in H13102. Depths from 1.0m CUBE surfaces compiled from the MBES data from each survey were compared using the CARIS HIPS Difference Surface function. A histogram of the differences is shown in Figure 7. Depths from the two surveys show good agreement with one another. The average difference between these surveys is 0.01m and 99.99% of the 1.0m comparison cells have differences within +/- 0.25m. Two (2) of the junction comparison cells have a difference above the discrepancy action threshold of 0.71m; however, both of these cells are located on a feature. Surface-to-surface difference histogram comparing Survey H13102 to H13103.file:///N:/Reports/DRs/H13102/H13102_Junction_H13103_Histogram.jpgSonar system quality control checks were conducted as detailed in the quality control section of the DAPR.None ExistThere were no conditions or deficiencies that affected equipment operational effectiveness.SSS RefractionDynamic sound speed changes affected the SSS imagery at times, causing refraction in the outer ranges of the SSS swath (Figure 8). To ensure that 100% coverage of high quality SSS data was acquired, when necessary, SSS lines with excessive refraction were rejected or the portion of the line with severe refraction was rerun. Due to the close line spacing employed in some locations, there were many instances of outer range refraction that did not trigger a re-run or rejection as high quality, 100% SSS coverage was achieved using only a portion of the imagery from a given line. For example, if refraction affected only the outer 20m of the 50m image range but the vessel was running on a 40m offset line plan, ample overlap was still achieved between adjacent tracklines resulting in greater than 100% SSS coverage of the area. In this scenario SSS imagery was not rejected.Refraction in the SSS imagery is visible in both channels of a survey line acquired with the fixed-mount 4125 SSS.file:///N:/Reports/DRs/H13102/H13102_FAS_SSS-Refraction.jpgSea State Induced White Streaks in SSS Imagery and MBES "Blowouts"The Reson 7125 system experienced periodic bursts of motion-induced noise or “blowouts,” typically affecting between 1 and 4 sequential profiles. Efforts were made to reduce this noise during acquisition, including adjustments to system gain and power, in addition to the multibeam pole fairing that was installed on the R/V Ocean Explorer to reduce cavitation effects. The noise bursts were infrequent and were encountered when sea state worsened. Accepted data affected by blowouts did not show any coverage gaps in excess of 3 x 3 nodes in the 1.0m MBES coverage surface. The fixed mount SSS data were also impacted by sea state conditions, such that when the wave frequency and height increased, more cavitation effects were observed near the transducer head with a dark return noted at the top of the water column in the raw SSS record. The cavitation noise at the transducer head resulted in intermittent black lines across the SSS record, which occasionally coincided with blowouts in the MBES data (Figure 9). The term "black line" is seen in the acquisition log to denote these types of events. The acquisition SSS waterfall was the opposite palette as the CARIS SSS palate. Therefore, a "black line" noted in the log coincides with a white line in CARIS. To ensure that 100% coverage was attained where the white streaks occurred, holiday fill-in lines were acquired over the location of the streaks with either MBES or SSS coverage as necessary.This figure shows how cavitation noise at the SSS and MBES transducer heads presented in the converted data. Noise at the 4125 TX head is visible as a dark return at the top of the water column with white streaking across the raw SSS imagery (bottom). In this instance, the SSS white streak coincided with an MBES blowout (top right and top left images).file:///N:/Reports/DRs/H13102/H13102_FAS_Streaks-and-MBES-Blowout.jpgFish in SSS Imagery and MBES DataAn abundance of fish and marine life were observed in the SSS and MBES data, either as lone swimmers or in schools, which at times created large shadows in the SSS imagery and gaps in the MBES data (Figures 10 and 11). Fish and dolphins were noted in the acquisition log by the field team, and these areas were carefully reviewed during data processing. Shadows in the SSS, usually detached from a dark return, were typically associated with fish either in the water column or at a position closer to nadir. In the cases where a visible shadow was recorded in the SSS, the contact was designated as a fish, for two reasons: 1) the possibility that the assumed fish was actually a feature and 2) to assist processors in rejecting fish-related noise from the MBES data. Over 10,000 fish contacts were identified in Survey H13102. To ensure that possible significant features were not located in these fish and dolphin shadows, the fish/dolphin related coverage gaps were rerun to achieve 100% SSS coverage or complete MBES coverage.SSS image showing a school of fish visible in the water column and a large "fish ball" on the starboard channel.file:///N:/Reports/DRs/H13102/H13102_FAS_Fish-SSS.jpgAn example of a dolphin as it appears in the water column of the MBES and the SSS, and the acoustic shadow cast in each dataset. In the top panel the rejected MBES soundings are colored yellow.file:///N:/Reports/DRs/H13102/H13102_FAS_Dolphin.jpgSound speed profile data were acquired with the ODIM MVP30 approximately every 15 minutes as documented in the DAPR.All MBES lines were sound speed corrected using CARIS HIPS' "Nearest in Distance Within Time" method. The time interval used was 1 hour. OSI submitted H13102 sound speed data in NetCDF format to the National Centers for Environmental Information (NCEI) on October 15, 2018 via the S2N tool. NCEI assigned the sound speed submission Accession Number 0177405. Correspondence regarding the NCEI data submission is included in Appendix II. This survey was conducted to develop 100% SSS coverage along with concurrent MBES with backscatter for all survey depths, i.e. Complete Coverage, Option B as defined in Section 5.2.2.3 of the HSSD 2017. For all disprovals either 200% SSS or Complete Coverage MBES was achieved. Per the HSSD which states "Gaps in 100% SSS coverage should be treated as gaps in coverage and addressed accordingly," gaps in SSS coverage and holidays caused by fish, dolphins, or white line noise were developed with Complete Multibeam or a second side scan coverage. All potentially significant features located with mainscheme SSS or MBES were developed with multibeam sonar data to meet HSSD 5.2.2.3 Complete Coverage requirements. All depths within Survey H13102 were shallower than 20m, for which HSSD 5.2.2.3 specifies a grid resolution of 1.0m. The survey methods used to meet coverage requirements did not deviate from those described in the DAPR.DensityThe CARIS HIPS and SIPS Compute Statistics tool calculated that 99.51% of the 1.0m grid nodes have 5 soundings or more, satisfying the density coverage requirements.All data reduction procedures conform to those detailed in the DAPR.All sounding systems were calibrated as detailed in the DAPR.Backscatter data were acquired concurrent with bathymetry data for Survey H13102. Backscatter data were recorded with HYSWEEP SURVEY in .7K format, and these data were periodically reviewed to ensure functionality of the backscatter acquisition process.CARISHIPS10.4CARISSIPS10.4NOAA Extended Attribute Files V5_8Software versions described in Section A of the DAPR were used throughout acquisition and processing of data for Project OPR-K354-KR-18.H13102_MB_1m_MLLWCARIS Raster Surface (CUBE)13.6613.02NOAA_1mComplete Coverage (Option B)H13102_SSS_1m_100SSS Mosaic1N/A100% SSSH13102_SSS_DisprovalSSS Mosaic1N/A200% SSSIn addition to the above grids, a higher resolution, 0.25m SSS mosaic image composed of all SSS lines was submitted in Enhanced Compressed Wavelet (ECW) format to assist with the survey review.Additional information discussing the vertical or horizontal control for this survey can be found in the accompanying Horizontal and Vertical Control Report (HVCR) for Project OPR-K354-KR-18.Mean Lower Low WaterERS via VDATUMOPR-K354-KR-2018_NAD83-MLLW_xGeoid17B.csarNorth American Datum 1983UTM Zone 15 NorthSmart BaseCalcasieu PassCALCEugene Island 337DEV1Abdalla Hall ULLTONYFranklin High SchFSHSAmerada PassAMERLumconLMCNHoumaHOUMOSI Freshwater LockOSFLApplication of the Applanix POSPac Smart Base process is described in detail in the project HVCR.English Turn, LACorrectors from the U.S. Coast Guard Differential GPS (DGPS) station in English Turn, LA were utilized by the secondary GPS, a Trimble MS750, used as a "position integrity" alarm. Chart comparisons were performed in CARIS HIPS/SIPS using finalized CUBE surfaces, contours and selected soundings. The latest edition of the NOAA NOS Electronic Nautical Chart (ENC) was downloaded from the NOAA Office of Coast Survey website (http://www.nauticalcharts.noaa.gov/) regularly during survey operations, and after the survey was completed for final comparisons. The ENC used for final comparison was updated with Notice to Mariners data through December 20, 2018 and is submitted with the survey deliverables. Local Notices to Mariners and Notices to Mariners from March 21, 2018 to December 20, 2018 were reviewed in conjunction with the chart comparison. During the chart comparison it was found that the shoalest soundings for charted regions were on shoal (seafloor) features. The chart comparisons documented below will discuss general seafloor changes, shoaling and deepening trends. All new or charted features identified, updated or disproved within Survey H13102 were addressed and attributed in the S-57 Final Feature File. For more information on the methodology that was used to build the FFF see Section B.2.5 Feature Verification in the DAPR.US4LA15M8000302018-12-202018-12-12falseAn overview of the areas of change between charted depths and H13102 surveyed soundings is shown in Figure 12. The figure displays a difference surface made by subtracting a 10m resolution depth surface generated from the H13102 MBES data from a depth surface interpolated from the charted ENC soundings within the project area. Regions of shoaling are represented by positive depth differences (warm colors) and regions of deepening are represented by negative depth differences (cool colors). There has been a deepening trend throughout much of the northern and southern regions of Survey H13102, with some shoaling or unchanged depths across the center and in the southwest corner of the sheet. Figure 13 shows US4LA15M ENC contours compared to H13102 surveyed contours generated from the displayed generalized tinned surface. The shoalest area of Trinity Shoal has migrated to west-northwest approximately 3000m and is no longer shoaler than 12 feet. The charted 12-foot contours over the previous shoal location are all disproved. The charted 18-foot depth contour encompassing Trinity Shoal has reduced in size within Survey H13102; the southern boundary of the 18-foot depth area has shifted northwards on the east side of the sheet by as much as 1600m. The northern boundary also shifted generally northwards but by a lesser extent. A depth area just south of Trinity Shoal on the west side of the sheet was added to the ENC as a result of H13102 DTON #2. This only represents a portion of the data from H13102. All of the data should be used to more thoroughly reflect the extent of change represented in H13101 DTON#2. The charted 30-foot contour in the southern end of Survey H13102 has shifted as much as 1100m north in the southeast corner of the survey and should be redrawn based on recently surveyed soundings. The charted 18-foot contour that enters and exits in the northwest corner of the survey is disproved. Survey depths were found to be deeper in this region. Charted depth contours have moved significantly from their charted location and should be redrawn based on data from H13102A depth difference surface overlaid on RNC 11349 provides an overview of the areas of change between charted depths and H13102 surveyed soundings.file:///N:/Reports/DRs/H13102/H13102_Difference_Map.jpgA colorized depth surface provides an overview of the change in contours from ENC US4LA15M to the surveyed data. RNC 11349 is displayed as an overlay.file:///N:/Reports/DRs/H13102/H13102_Chart-Comparison.jpgNo Maritime Boundary Points were assigned for this survey.The Project Instructions' guidance on Shoreline and Nearshore Features states, "Submit a Final Feature File in accordance with HSSD Section 7. Contact the COR if there are any questions regarding feature assignments and feature management. All features with attribute ‘asgnmnt’ populated with ‘Assigned’ shall be addressed in accordance with Chapter 7 of the HSSD. Investigation requirements for all assigned features will be provided in the investigation requirement attribute ‘invreq.’ For the purposes of disproval, charted features labeled with a "PA" will have a search radius of 160 meters, charted features labeled with a "PD" will have a search radius of 240 meters, and other features without a position qualifier will have a search radius of 80 meters. With respect to wellheads, reference HSSD Chapter 7.5.1." The disproval area for wellheads given in the referenced HSSD chapter is a 50m search radius. Guidance on attribution of charted and CSF-assigned features varies between NOS-NOAA documents pertaining to this survey. For example, guidance on New/Delete vs. Update attribution is quite detailed in the HSSD Section 7.5.2 which lists numerous attribution change thresholds. In contrast, the CSF investigation requirements for platforms states, "If feature exists, include in FFF with descrp=retain. If feature is not visible, conduct a feature disproval (Section 7.3.4)." The addition of uncharted BSSE Wellheads in the CSF (which were often closer to a surveyed platform than the CSF-defined position of the platform) creates further uncertainty on how to attribute certain features. Given the ambiguity in directives, OSI consulted with the COR for clarification via e-mail on December 6, 2017. The COR's December 11, 2017 response follows: "Include both the significant wellheads and platform features in the FFF, and reposition any platform that deviates greater than 10 meters from the center point of the corresponding charted feature, based on the Page 97 of the HSSD.  These are all delete/add for the charted platforms." A record of this correspondence is included in DR Appendix II. Within the bounds of Survey H13102, 44 charted features were investigated: 6 platforms, 1 submarine cable, 8 pipeline sections, and 29 obstructions. All of the assigned obstructions were "BSSE Wellhead" obstructions. Three (3) of the 6 assigned platforms were verified and included in the FFF at their surveyed position. The remaining 3 platforms were disproved. See DR Section D.2.6 Platforms for further information regarding the verification or disproval of the charted platforms. All BSSE Wellhead obstructions are recommended for deletion. Of the 29 BSSE Wellhead obstructions, 3 were coincident with verified and charted platforms, but no evidence of a wellhead aside from the verified platform was found within the disproval area. Each of the remaining 26 BSSE Wellhead obstructions were disproved with 200% SSS and partial MBES or with complete MBES coverage. One (1) submarine cable feature was assigned for investigation in the CSF. The cable was not detected in the survey data and is not included in the FFF, as directed by the Investigation Requirements in the CSF. Eight (8) charted pipeline features are present within the bounds of Survey H13102 and assigned in the CSF. Many of the pipelines, as packaged and assigned in the CSF, extend outside the bounds of the H13102 survey area and were not investigated beyond the survey limits. During preliminary data processing there were numerous pipeline or potential pipeline detections identified in Survey H13102. Many of these detections are duplicate detections from a single feature imaged on one or more adjacent tracklines, leaving 11 unique potential pipeline features. A number of these potential detections were later determined to be something other than an exposed pipeline, e.g. exposed pipe armor or a low-relief escarpment. Five (5) pipeline features were confirmed. All pipeline detections are less than 1.0m above the seafloor, and therefore, are not deemed DTONs. The valid pipeline detections, as interpreted during late-stage processing, were forwarded to the COR via email on November 16, 2018 according to guidance in Section 1.7 of the HSSD regarding Non-DTON Seeps and Pipelines. Prior to 2017, exposed pipes and seeps were handled as DTONs and therefore were appended to the FFF. The 2017 HSSD includes a new category of feature, "non-DTON seeps and pipes." However, the 2017 HSSD does not mention whether or not to include these non-DTON features in the FFF. The HSSD only addresses undetected charted pipelines and recommends that a non-detected pipeline should be attributed "Retain." In a December 11, 2017 e-mail to the COR, OSI inquired about how to treat exposed, non-DTON pipes and seeps in the FFF. The COR's December 12, 2017 response follows, "The current requirement of the "Non-DTON Seep and Pipeline Report" is a separate deliverable from the FFF.  Your historic method of including the pipeline segments in the FFF is good.  How you manage the other features is up to your discretion. The features that are not cartographically significant they will be ignored in the FFF." Given this latitude in how to treat the non-DTON seeps and pipes, OSI chose to include them in the FFF as discrete features.In general there were very few new features surveyed in H13102. Of the relatively few SSS contacts chosen, most were either fish (chosen independently of the mass fish targeting scheme described in the DAPR) or features of insignificant height. There are 3 new obstructions included in the FFF, 1 of which was submitted as a DTON on September 21, 2018. The DTON is an obstruction with a height of approximately 2.25m, located near a pipe arch in the southwest corner of the survey area. The 2 non-DTON obstructions are not sufficiently proud of the seafloor to be a danger to navigation, but they are of noteworthy size. One obstruction, located in the southeastern quadrant of the survey area, is a large square object of approximately 20m per side (Figure 14). The object has a solid, relatively flat surface and is angled upwards off the seafloor over a depression. It reaches a height of approximately 2m from the bottom of the depression, but it extends only 0.6m above the surrounding seafloor surface. The second obstruction, located in the southwest quadrant of the survey area, is a square structure of approximately 4m per side and is nominally 1.5m tall. However, it is situated in a depression in the seafloor such that the top of the object is approximately 0.45m proud of the surrounding seafloor surface (Figure 15). A nominally 2m tall obstruction represented in CARIS HIPS Subset Editor 3D with the soundings colored by depth.file:///N:/Reports/DRs/H13102/H13102_29-11-47.76N_92-13-03.50W_3-031_OBSTN.JPGA nominally 1.5m tall obstruction represented in CARIS HIPS Subset Editor 3D with the soundings colored by depth.file:///N:/Reports/DRs/H13102/H13102_29-11-10.08N_92-17-09.54W_3-128_OBSTN.JPGTwo (2) hazardous features were surveyed in H13102; 1 obstruction, discussed above in D.1.4 Uncharted Features, and 1 shoal feature associated with what appears to be a large scale mobile bedform. A portion of Trinity Shoal is included in the survey area, and the top of the shoal appears to have migrated approximately 1.6nm west-northwest from its previously charted position. Two (2) DTONs were generated as a result of this survey.No channels exist for this survey. There are no designated anchorages, precautionary areas, safety fairways, traffic separation schemes, pilot boarding areas, or channel and range lines within the survey limits.Six (6) bottom samples were acquired in close proximity to the recommended positions included in the PRF provided with the OPR-K354-KR-18 Project Instructions. A sediment sampler was deployed from a davit to acquire the requisite sample. Bottom sample locations were logged in a target file in HYPACK SURVEY. Once the sample was on deck, it was photographed and classified based on the criteria outlined in Appendix H, Bottom Classification, in the HSSD. Sediment within Survey H13102 was primarily found to be fine sand with mud, with some samples also containing broken shells. Shoreline was not assigned in the Hydrographic Survey Project Instructions or Statement of Work.Prior survey comparisons exist for this survey, but with the exception of the assigned junction surveys, prior data were not investigated.No Aids to Navigation (ATONs) exist for this survey.No overhead features exist for this survey.Within Survey H13102, 8 charted pipelines and 1 charted cable were assigned in the CSF. The majority of the charted pipelines were not visible in the SSS or MBES data, nor was the charted cable. In addition to the ENC and the CSF, pipeline data from the Bureau of Ocean Energy Management (BOEM) were reviewed prior to field operations to identify potential uncharted BOEM pipelines in the survey area. Two (2) BOEM pipelines are not represented on the chart and 2 charted pipelines do not have a BOEM pipeline counterpart. Uncharted BOEM pipelines as well as the charted pipelines without a BOEM pipeline counterpart are displayed in Figure 16. The BOEM pipeline data (last updated on December 3, 2018) were obtained as a shapefile "ppl_arcs.shp" from the BOEM website (https://www.data.boem.gov/Main/Mapping.aspx) and re-projected as a .DXF file "BOEM_Pipelines_UTM_15N_NAD83_Meters.dxf." These files are included with the digital deliverables for Survey H13102.BOEM-defined pipelines that are not charted are highlighted in yellow. The charted pipelines without a BOEM counterpart are highlighted in blue. Survey H13102 survey boundary limits are shown in black.file:///N:/Reports/DRs/H13102/H13102_BOEM_Pipeline_Analysis.jpgOf the 6 platforms assigned for investigation for Survey H13102, 3 were found to be present. All 3 surveyed platforms are charted on the ENC and assigned for investigation in the CSF. However, these platforms were greater than 10m from their CSF positions and as such were marked for deletion and new platforms were added to the FFF at their surveyed locations. The remaining 3 platforms assigned in the CSF were disproved and are recommended for deletion. In addition to the ENC and the CSF, BOEM platform data were reviewed prior to field operations to identify any potential uncharted BOEM platforms in the survey area. There were 7 BOEM defined platforms in the dataset, 3 of which coincide with the general location of the 3 surveyed platforms. All 7 BOEM platforms coincide with either an assigned BSSE Wellhead or a charted pipe/platform. The BOEM platform data (last updated on December 3, 2018) were obtained as a shape file "platforms.shp" from the BOEM website (https://www.data.boem.gov/Main/Mapping.aspx) and re-projected as a .DXF file “BOEM_Platforms_UTM_15N_NAD83_Meters.dxf.” These files are included with the digital deliverables for Survey H13102. There were no platform related Local Notice to Mariners or Notice to Mariners notifications within Survey H13102 from March 21, 2018 to December 20, 2018.No ferry routes or terminals exist for this survey.There is evidence of long term sediment transport within the survey area, i.e. the shoal soundings of Trinity Shoal appear to be migrating westward. During the period of the survey, evidence of short term sediment movement was also observed. Figure 17 depicts a portion of the shoal surface from the northern edge of Survey H13102. Water depth in this area is around 6.2m. Featured in the image are MBES data from a crossline acquired on DN 166, mainscheme lines acquired on DN 173, and investigation lines including a "sounding star" investigation acquired on DN 211. Between DNs 166 and 173 was a weather event of several days with wind speeds of up to 35 knots. The contrast from the smooth tie line to the mainscheme lines with a textured seafloor after the weather event is evident in the figure. There was not a large scale weather event between DN 173 and DN 211, but the investigation lines surveyed on DN 211 are once again smooth, without the bottom texture observed on DN 173. Figure 18 depicts a portion of the shoal surface from the southern portion of Survey H13102. Water depth in this area is around 9.1m. Featured in the image are MBES data from a crossline acquired on DN 165 and mainscheme lines acquired on DN 194, showing that in between their acquisition dates, a depression formed at the location where the two lines intersect. The frequency of depressions on the mainscheme data and the lack of depressions on the tie lines suggests that many, if not all, of these depressions were formed during that intervening time period. Example of ongoing sediment transport in H13102, with the bottom character changing multiple times during the survey period.file:///N:/Reports/DRs/H13102/H13102_DN166-DN173-DN211_bottom-texture.jpgExample of sediment transport in H13102 which occurred over a relatively short time period.file:///N:/Reports/DRs/H13102/H13102_DN165-DN194_bottom-depressions.jpgNo present or planned construction or dredging exist within the survey limits.Marine Mammal ObservationsPer direction in Section 1.5 of the HSSD, all personnel aboard the survey vessel used during Project OPR-K354-KR-18 were trained as Marine Mammal Observers prior to commencement of the survey. Training consisted of each surveyor and vessel crew member watching the US Navy video referenced in the HSSD. As noted multiple times in the survey acquisition log, large, mobile water column sonar targets (assumed to be dolphins) were ensonified by either the MBES or the SSS. The dolphin-assumption is based on both the size and behavior of the sonar targets. Often times these observations did not coincide with a visual (above water) sighting. Visual observations, when noted, were recorded on NOAA/NMFS,AFSC/NMML Form 11US (POP) which is included as Appendix L of the HSSD. Completed digital 11US (POP) forms were compiled and transmitted along with the Project's digital marine mammal training record to pop.information@noaa.gov and ocs.ecc@noaa.gov with a CC to the Project's COR, Starla Robinson. These records are also included in Descriptive Report Appendix II. Coast Pilot ReviewIn reference to the OPR-K354-KR-18 survey area the Coast Pilot Report, included with the April 4, 2018 Final Data Package, states that, "there is one paragraph in Coast Pilot 5, chapter 9, that describes Trinity Shoal (paragraph 301). There are no details on the surrounding area either. The paragraph appears to be accurate to Chart 11349 and does not need an update." The survey area considered in the Coast Pilot Report does not exactly match the area ultimately surveyed (the assigned survey area expanded after issue of the April 4, 2018 Final Data Package). However, the Report's "no updates needed" statement and the lack of other investigation requirements still applies to the area actually surveyed. The Hydrographic Survey Project Instructions contained only general guidance regarding the Coast Pilot. Therefore, in lieu of targeted responses to an assigned Coast Pilot Field Report, OSI conducted a general review of relevant Coast Pilot excerpts. Specifically, pertinent paragraphs from the following Coast Pilot section were considered: Coast Pilot 5 - 46th Edition, 2018 updated through 21-October-2018, Mississippi River to Sabine Pass. Within the Coast Pilot Edition mentioned above there is only one specific, detailed, relevant entry concerning the assigned survey area. Most entries are of a general nature and are not refutable based on the observations of the OSI field team. Regarding “areas frequently transited and facilities utilized during in-ports” (as mentioned in the HSSD Section 8.1.3) Coast Pilot entries are somewhat more relevant. However, there are only a few Coast Pilot entries that this document will attempt to address as most entries are not relevant to the "areas frequently transited by the survey vessel and facilities utilized during in-ports." OSI's Coast Pilot Review Report and the original Coast Pilot Report, mentioned above, were transmitted to ocs.nbd@noaa.gov and coast.pilot@noaa.gov with a CC to the Project's COR, Starla Robinson. These records are also included in Descriptive Report Appendix II.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 Specifications and Deliverables, Field Procedures Manual, Letter Instructions, and all HSD Technical Directives. These data are adequate to supersede charted data in their common areas. This survey is complete and no additional work is required with the exception of deficiencies noted in the Descriptive Report.George G. ReynoldsChief of Party2019-01-25John R. BeanLead Hydrographer2019-01-25David T. SomersData Processing Manager2019-01-25Data Acquisition and Processing Report2019-01-25Horizontal and Vertical Control Report2019-01-25Coast Pilot Report2018-11-15