OPR-K354-KR-17Louisiana CoastGulf of MexicoOcean Surveys, Inc.H130401Tiger ShoalLouisianaUnited States400002017George G. ReynoldsNavigable Area2017-06-212017-08-032017-10-12Multibeam Echo SounderSide Scan SonarMultibeam Echo Sounder 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 BASE SURFACES REPRESENTS THE RESULTS OF SURVEYS PERFORMED BY OCEAN SURVEYS, INC. DURING THE PERIOD OF 3 AUGUST 2017 TO 12 OCTOBER 2017 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. ContractorThis survey provides hydrographic data for the Gulf of Mexico waters approaching the Louisiana Coast south of Marsh Island. The general locations of the survey limits are presented in Table 1. 29.396905944492.239163888929.306188222292.0073796944Survey limits were acquired in accordance with the requirements in the Project Instructions and the HSSD.Per the Hydrographic Survey Project Instructions: 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, LA. The survey will address concerns of migrating shoals and exposed hazards by updating bathymetry and positions of hazards, reducing the risk to navigation. 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 will intersect with the Gulf of Mexico Intracoastal Waterway. The Port serves the offshore oil, shrimping, seafood, chemicals, and machinery industries. 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 185 square nautical miles of high priority survey area identified in the 2017 Hydrographic Health model. Adjacent modern surveys show shoaling, with contours that have migrated up to 9 miles since the 1935 vintage source surveys. The adjacent 2016 Atchafalaya survey uncovered numerous exposed pipelines and hazards. This project will significantly update the chart. Data from this project will supersede all prior survey data in the common area.The entire survey is adequate to supersede previous data.All waters in survey areaLNM not to exceed 6300 LNM. Acquire backscatter data during all multibeam data acquisition (HSSD Section 6.2). Report significant shoaling via weekly progress report. COR may adjust survey prioritization based on observed shoaling.Inshore limit to 4 meters water depth for H13041 - H13043200 meter set line spacing HSSD Section 5.2.2.4 Option A.Greater than 4 meters water depth for H13041 - H13043Complete Coverage (refer to HSSD Section 5.2.2.3)All waters in survey area of H13040Complete Coverage (refer to HSSD Section 5.2.2.3)Disproval radius of features in all watersComplete Coverage (refer to HSSD Section 5.2.2.3)Survey Coverage is in accordance with the requirements in the Hydrographic Survey Project Instructions (June 21, 2017), the Statement of Work, [May 18, 2017 (SOW)], 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 for charted feature disprovals. Gaps in the 100% SSS coverage were addressed with SSS fill-in lines or covered with complete MBES data. Bathymetric splits 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. The final survey area covers 56.48 square nautical miles (Figure 1).Survey H13040 MBES coverage overlaid on RNC 11340.file:H13040_Figure_1_Coverage_Graphic.jpgR/V Ocean Explorer "OE"000001893.070135.150R/V Osprey "SB"036.54000172.12000036.540002065.180135.1506.41000056.482017-08-042017-08-052017-08-062017-08-072017-08-082017-08-092017-08-102017-08-112017-08-122017-08-132017-08-142017-08-152017-08-172017-08-182017-08-192017-08-202017-09-012017-09-022017-09-032017-09-182017-09-192017-09-202017-09-212017-10-112017-10-12The lineal nautical miles (LNM) for MBES only development and fill in lines were included under the heading "Mainscheme MBES" in Table 2, Hydrographic Survey Statistics. There was no SSS-only mileage for this survey. Refer to the OPR-K354-KR-17 Data Acquisition and Processing Report (DAPR) for a complete description of data acquisition and processing systems, survey vessels, 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 Explorer "OE"182R/V Osprey "SB"7.90.6The survey was conducted employing two vessels. Much of the relatively deep reaches of the study area were surveyed using the R/V Ocean Explorer. A smaller vessel, the R/V Osprey, surveyed relatively shallow reaches of the study area as well as certain “deep” water areas. For the sake of clarity, especially as concerns the field data file naming convention, two distinct abbreviations are employed. Specifically, files generated on the R/V Ocean Explorer include “OE” in the name and files generated on the R/V Osprey include “SB” which is meant to indicate “small boat” files. Onboard the R/V Ocean Explorer--EdgeTech4125SSSTeledyne RESONSeaBat 7125 SV2MBESODIM Brooke OceanMVP30Sound Speed SystemAML OceanographicMicro XSound Speed SystemAML OceanographicBase XSound Speed SystemApplanixPOS MV 320 v4Positioning and Attitude SystemTrimbleProBeaconPositioning SystemTrimbleMS750Positioning SystemOnboard the R/V Osprey--EdgeTech4125SSSTeledyne RESONSeaBat 8125MBESSea-Bird ScientificSBE-37Sound Speed SystemAML OceanographicBase XSound Speed SystemApplanixPOS MV 320 v5Positioning and Attitude SystemLeicaMX52RPositioning SystemTrimbleDSM232Positioning SystemTable 5 summarizes the primary equipment used on the respective vessels to acquire MBES and SSS data. All equipment was installed, calibrated and operated in accordance with the DAPR.A total of 135.15 nm of crossline data were acquired August 4-5, 2017 (DN 216-217). Crosslines were run nominally perpendicular to mainscheme lines (Figure 2). Crosslines were acquired exclusively by the R/V Ocean Explorer. The majority of mainscheme line miles were also surveyed by the R/V Ocean Explorer. However, the R/V Osprey acquired approximately 130 nm of shallow water mainscheme sounding data through which a number of crosslines pass. Soundings from mainscheme lines and crosslines were compared periodically throughout survey operations 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-meter CUBE surface composed only of crossline data and the depth layer of a 1-meter CUBE surface composed only of mainscheme data. The crossline analysis results demonstrate good agreement between crossline soundings and mainscheme soundings, with the depth differences less than or equal to 0.54 meters with an average difference of 0.08 meters. The allowable TVU for the range of water depths within Survey H13040 is 0.50 to 0.51 meters. Figure 3 is a histogram showing the distribution of depth differences for all comparison grid cells considered. The total number of 1-meter comparison cells equaled 1,433,913. Of 1,433,913 possible comparison cells, 1,395,602 or 97.32% of the cells include crossline and mainscheme soundings that match within +/- 25 centimeters and 99.99% that match within 50 centimeters.An overview of the crossline layout on a 1-meter surface created from mainscheme MBES data and colored by depth. RNC 11349 is visible in the background.file:H13040_Figure_2_Crosslines.jpgThe graph shows a frequency distribution of the depth differences between the H13040 crossline data and the H13040 mainscheme MBES data. Statistics from the depth difference sample set are displayed above the graph.file:H13040_Figure_3_CC_XL.jpg0.010.19Discrete ZoningR/V Ocean Explorer12R/V Osprey42The 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 H13040 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. 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". A finalized surface was used in this analysis. The surface was finalized using the “greater of the two” option as the basis for calculating “Final Uncertainty” in the CARIS “Finalize Base Surface” utility. One (1) MBES CUBE (Combined Uncertainty and Bathymetric Estimator) surface was delivered along with Survey H13040; "H13040_MB_1m_MLLW_Final." 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 less than -1. Of the 67,717,316 nodes considered, 92 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.Two (2) prior surveys and one (1) contemporary survey junction with Survey H13040. Figure 4 displays the location of the prior and contemporary junction surveys for Project OPR-K354-KR-17. The allowable TVU for the range of water depths within Survey H13040 is 0.50 to 0.51 meters. Therefore, according to the XMLDR Junction Area "maximum difference" threshold guidance equation (SQRT2 * TVU) the junction discrepancy action threshold = 0.71 meters.Survey junctions for Project OPR-K354-KR-17. RNC 11340 is displayed in the background.file:H13040_Figure_4_Junctions.jpgH11669200002007C&CNSurvey H11669, a MBES/SSS survey conducted by C&C in 2007-2009, overlaps the northern border of H13040. Survey H11669 and Survey H13040 were run with the intention of achieving either 200% or 100% SSS coverage respectively. As such, each survey's MBES coverage is essentially "skunk stripe coverage." The mainscheme line plan for each survey was oriented nominally east-west with crosslines oriented nominally north-south. The common border length is approximately 6,900 meters. The junction area between the surveys is relatively sparse. Parallel skunk stripe mainscheme lines have an overlap of approximately 70 meters and the combined crossline overlap into the adjacent survey areas is as much as 500 meters. Depth data for Survey H11669 were downloaded from the National Geophysical Data Center (NGDC) website (http://www.ngdc.noaa.gov) in the form of a 2-meter resolution Bathymetric Attributed Grid (BAG), "H11669_2m_MLLW_6of6.bag." To conduct the junction comparison a 2-meter CUBE surface was generated from the entire MBES data set for Survey H13040, "H13040_MB_2m_MLLW." In CARIS HIPS, depths from the "H11669_2m_MLLW_6of6" BAG were subtracted from the depths in the "H13040_MB_2m_MLLW" CUBE surface using the CARIS HIPS Difference Surface function. A histogram of the differences is shown in Figure 5. Depths from the H13040 survey show decent agreement with depths from the H11669 survey. Depth discrepancies equaled 51 centimeters or less with a mean difference of 11 centimeters. On average, Survey H11669 depths were deeper than H13040 depths which, overall, is likely due to sediment transport in the H13040 survey area since the 2007-2009 survey was conducted. The magnitude of differences is spatially random but like-magnitude differences are regionally concentrated, i.e. differences are not line-by-line which might suggest a tide or systematic deficiency in one of the surveys. In fact, depth changes throughout Survey H13040, as compared to the remaining junction surveys and the presently charted depths, suggest that the entire survey area is prone to depth changes due to sediment transport. All (100%) junction comparison cells have a difference < 0.71 meters. Surface-to-surface difference histogram comparing Survey H13040 to H11669.file:H13040_Figure_5_H11669_Junction.jpgH11670200002007C&CNSurvey H11670, a MBES/SSS survey conducted by C&C in 2007-2008, overlaps the northern border of H13040. Survey H11670 and Survey H13040 were run with the intention of achieving either 200% or 100% SSS coverage respectively. As such, each survey's MBES coverage is essentially "skunk stripe coverage." The mainscheme line plan for each survey was oriented nominally east-west with crosslines oriented nominally north-south. The common border length is approximately 15,400 meters. The junction area between the surveys is relatively sparse. Parallel skunk stripe mainscheme lines have an overlap of approximately 30 meters and the combined crossline overlap into the adjacent survey areas is as much as 475 meters. Depth data for Survey H11670 were downloaded from the National Geophysical Data Center (NGDC) website (http://www.ngdc.noaa.gov) in the form of 2-meter resolution Bathymetric Attributed Grids (BAG), "H11670_2m_MLLW_1of6.bag" and "H11670_2m_MLLW_6of6.bag" To conduct the junction comparison a 2-meter CUBE surface was generated from the entire MBES data set for Survey H13040, "H13040_MB_2m_MLLW". In CARIS HIPS, depths from the "H11670_2m_MLLW_1of6" and "H11670_2m_MLLW_6of6" BAGs were subtracted from the depths in the "H13040_MB_2m_MLLW" CUBE surface using the CARIS HIPS Difference Surface function. A histogram of the differences is shown in Figure 6. Overall, depths from the H13040 survey show decent agreement with depths from the H11670 survey. In the extreme, depth discrepancies range from -1.39 meters to +1.29 meters. However the mean difference between surveys is only 8 centimeters. On average, Survey H11670 depths were deeper than H13040 depths. Area specific shoaling and deepening trends are observed in the overlapping datasets. As mentioned in the H11669 Junction discussion above, it is surmised that sediment transport has occurred since the 2007-2008 survey. The largest discrepancy between survey depths (in the area of maximum difference range described above) occurs on Tiger Shoal where the peaks of what is interpreted to be a mobile bedform appear to have moved west since the 2007-2008 survey. Most (99.02%) junction comparison cells have a difference < 0.71 meters. Surface-to-surface difference histogram comparing Survey H13040 to H11670.file:H13040_Figure_6_H11670_Junction.jpgH13041400002017Oceans Surveys, Inc.EThe approximate overlap between the bathymetric data from contemporary Surveys H13040 and H13041 was approximately 300 meters along a common border of approximately 8,000 meters. Both surveys were acquired to meet 100% SSS Coverage, not complete MBES coverage. Given the fact that the respective line plans meet at an obtuse angle there is a fair amount of overlapping data despite the skunk stripe nature of MBES coverage. Depths from 1-meter BASE surfaces compiled from the MBES data from each survey, "H13040_MB_1m_MLLW" and "H13041_MB_1m_MLLW," were compared using the CARIS HIPS Difference Surface function. A histogram of the differences is shown in Figure 7. Depths from the H13040 survey show good agreement with the depths from the H13041 survey. Depth discrepancies generally equaled 25 centimeters or less with a mean difference of 2 centimeters. Differences appear to be tide related. All (100%) junction comparison cells have a difference < 0.71 meters. Surface-to-surface difference histogram comparing Survey H13040 to H13041.file:H13040_Figure_7_H13041_Junction.jpgSonar system quality control checks were conducted as detailed in the Quality Control section of the DAPR. Results from the MBES bar checks are included in Appendix II of the DAPR.R/V Ocean Explorer MBES Time Sync ErrorsOnboard the R/V Ocean Explorer occasional time sync alarms were observed on the Reson 7125 Seabat display during data acquisition. This phenomenon did not occur on the R/V Osprey (using a Reson 8125). The field personnel noted that along with the time sync alarm a brief gap may be observed in the real time display of the Seabat waterfall window. In some cases these events resulted in what appeared to be a gap in the recorded HYPACK .HSX file. Using an EXCEL utility developed by OSI, each and every HYPACK .HSX file was analyzed for these types of gaps upon check-in to the data processing flow. Upon review of the HYPACK .HSX files affected by the time sync gaps, it was noted that the sounding pings were in fact present but, a number of sounding pings would be time tagged with identical times. It is surmised that the gaps are not due to the Reson multibeam hardware, rather that the gaps are associated with acquisition computer buffering. The majority of gaps were less than 1 second. Throughout the entire project, 69 time sync gaps were detected. When possible (and practical) the HYPACK .HSX time-stacked sounding pings were manually edited and the time stamps rewritten (interpolated/advanced at a 1/15 second interval until proper timing was reacquired). The 1/15 second interval was chosen because the sonar ping rate was limited, via user control, to a rate of 15 pings/second and the sonar range was maintained at a setting that did not limit the pings below 15/second. The affected lines were not converted to CARIS HDCS data until the time stacking editing had been completed. There were certain cases when a given gap was deemed unrepairable based on its duration or its relative location within a file. By manually editing certain HYPACK .HSX files many lines were "saved." In some cases a gap occurred outside the bounds of the survey area or in an area with adjacent line overlap. In these cases the affected data were rejected. Between "saving" lines and rejecting certain affected data none of the delivered data contain gaps that exceeded 3x3 surface nodes in the 1-meter Complete Coverage surface.POSPac TrueHeave gapsEspecially during the first few days of data acquisition (DN 218, DN 219, DN 220) and periodically thereafter the recorded, stand-alone Applanix POSPac files were affected by occasional brief network interruptions with durations on the order of around 5 to 22 seconds. It was believed initially that the cause of the outages was a faulty network cable on the R/V Ocean Explorer (which was replaced on DN 221). However, additional outages on the R/V Ocean Explorer after DN 221 and the fact that both vessels ultimately experienced outages suggest that network collisions may have been the culprit. The result of the network interruptions is an associated gap in the TrueHeave or delayed heave record for each file affected. It turns out that a number of the gaps described herein occur between times of data acquisition, e.g. before the start of acquisition for the day or between lines. For those files affected a custom "repair" was undertaken. CARIS HIPS does not allow for application of TrueHeave files with data gaps. Rather than forgo using the discontinuous TrueHeave files, OSI developed a utility to “fill” TrueHeave gaps with the real-time heave data recorded by HYPACK. In practice the utility loops through a given POSPac file and searches for gaps in the TrueHeave record of > 0.1 second. If a gap is detected the utility then polls the appropriate HYPACK .HSX file and extracts the non-delayed, real-time heave values for the period of the data gap. Finally, a TrueHeave file (supplemented with real-time heave as appropriate) is written as a TrueHeave group 111-only file (.000 format). During data check-in each and every POSPac file was analyzed for TrueHeave gaps. For the few days affected by the network interruptions, the OSI utility-generated .000 files were used in lieu of the POSPac .000 file for application of TrueHeave. The analysis and generation of “repaired” files described above were undertaken prior to ingestion into the CARIS HIPS data processing work flow. The "repaired" files include a "TH" for TrueHeave in the file name instead of the OSI default notation of "POS." For example, a file named "17ES024_OE_2017_TH_219_0807.000" was generated after repairing the POSPac file named "17ES024_OE_2017_POS_219_0807.000." It is important to note that at no time did the network outages described above result in an interruption to the real time network stream as recorded by HYPACK. On August 7, 2017 (DN219) one POSPac TrueHeave file was not recoverable from the data disk due to a computer crash. These MBES data affected by this lost file, 17ES024_OE_2017_POS_219_0807_2.017, were processed using the real time heave. The non-recoverable file affected only one MBES file, 2017OE2191401_5004.HSX. 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 re-run. Due to the relatively shallow water depths and the relatively close line spacing employed in some locations, there were many instances of outer range refraction that did not trigger a re-run or rejection. In these cases 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 20 meters of the 50 meter image range but the vessel was running on a 40 meter 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:H13040_Figure_8_Refraction.jpgSea State Induced White Streaks in SSS Imagery and MBES "Blowouts"Both the Reson 7125 and Reson 8125 systems 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 only) 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-meter 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:H13040_Figure_9_SSS_White_Line%20and%20MB%20Blowout.jpgTide OffsetReview of surface data indicated that there were a number of minor tide-related offsets between MBES data collected on different days scattered throughout Survey H13040. There were no noteworthy tide events that affected this survey. However, there was a consistent offset on the scale of 10 to 30 centimeters between the predicted and verified tides at the LAWMA, Amerada Pass LA tide station during the period of the survey. Overall, the tide correctors were modeled well for Survey H13040, showing good agreement between survey days. Tide offsets generally equaled 20 cm or less and are likely associated with local environmental effects, i.e. wind setup. Figure 10 highlights a portion of the survey area where a tide offset was noted between a crossline from DN 217 and mainscheme data from DN 220 and DN 223 . The left image shows a subset window displayed over the Standard Deviation layer from the H13040 1-meter CUBE surface. The yellow/green colors indicate areas of higher standard deviation in the surface due to a tide offset. The right image displays MBES data loaded into CARIS Subset Editor with a tide offset noted between DN 217 (dark green) and some of the survey lines from DN 220 (light green). Other lines from DN 220 (light green) and DN 223 (purple) agree with the crossline depth. Depths and distances are in meters.file:H13040_Figure_10_Tide_Offset.jpgFish in SSS Imagery and MBES DataAn abundance of fish and marine sea life were seen in the SSS and MBES data, either as lone swimmers or in schools (Figures 11-13). 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. Dolphin pods were present within the survey area, as well as large schools of fish, which at times created large shadows in the SSS imagery and gaps in the MBES data where soundings on fish and dolphins were rejected. To ensure that possible significant features were not located in these fish and dolphin shadows, these fish/dolphin related coverage gaps were developed with 200% SSS coverage or complete MBES coverage. As compared to the other three survey sheets in this project, Survey H13040 had the least amount of fish and dolphin interference. Over 14,000 fish contacts were identified in Survey H13040.A school of individual large fish as it appears in the MBES data and in the water column of the raw, un-slant range corrected SSS imagery. The image on the top was taken from the CARIS Subset Editor 3D window with rejected soundings, in this case returns off of the individual fish, colored yellow.file:H13040_Figure_11_Fish-MBES-SSS.jpgSSS image showing a large "fish ball" on the starboard channel.file:H13040_Figure_12_Fish_Ball.jpgAn example of a dolphin as it appears in the water column of the MBES and un-slant range corrected SSS and the acoustic shadow cast in each dataset. In the top panel the rejected MBES soundings are colored yellow.file:H13040_Figure_13_Dolphin-MBES-SSS.jpgOnboard the R/V Ocean Explorer sound speed profile data were acquired with the ODIM MVP30 approximately every 15 minutes as documented in the DAPR. On the R/V Osprey sound speed profiles were acquired at an interval of approximately 1-2 hours or better.All MBES lines were sound speed corrected using CARIS HIPS' "Nearest in Distance Within Time" method. For MBES data acquired by the R/V Ocean Explorer the interval used was one (1) hour. For MBES data acquired by the R/V Osprey the interval used was two (2) hours. For the duration of data acquisition for Project OPR-K354-KR-17, the water column was relatively well-mixed. OSI submitted H13040 sound speed data in NetCDF format to the National Centers for Environmental Information (NCEI) on December 7, 2017 via the S2N tool. NCEI assigned the sound speed submission Accession Numbers 0169266 and 0169267. 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. All depths within Survey H13040 were shallower than 20 meters. Per the HSSD which states "Gaps in SSS coverage should be treated as gaps in MBES 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 high density multibeam sonar data to meet the Project Instructions/HSSD requirement of Complete Coverage Multibeam. The survey methods used to meet coverage requirements did not deviate from those described in the DAPR.DensityTo confirm the HSSD Density coverage requirements, the Compute Statistics tool was utilized within CARIS HIPS and SIPS to generate statistics for the Density layer of the CUBE surface. The HSSD states that at least 95% of the surface nodes shall be populated with at least 5 soundings for the Complete Coverage (Option B) 1-meter surface. The Compute Statistics tool generates an ASCII export containing two columns: 1) sounding density value and 2) the number of nodes that returned that value. This export was used to determine the percentage of nodes with a sounding density greater than or equal to 5 for the submitted CUBE surface. The percentage of nodes with density greater than or equal to 5 soundings for the 1-meter Complete Coverage surface is as follows: H13040_MB_1m_MLLW_Final = 99.14%. 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 H3040. Backscatter data were recorded with HYSWEEP SURVEY in .7K format or .81X format by the R/V Ocean Explorer and R/V Osprey respectively. These data were periodically reviewed to ensure function of the backscatter acquisition process. No specific instructions were made in the Project Instructions regarding coverage, ground truthing or processing for the Backscatter data, as such, these data are delivered in raw format in the "Preprocess\MBES” directory per the HSSD, Section 8.3.4 Backscatter Deliverables.CARISHIPS10.4CARISSIPS10.4NOAA Profile V_5_5Software versions described in Section A of the DAPR were used throughout acquisition and processing of data for Project OPR-K354-KR-17.H13040_MB_1m_MLLW_FinalCARIS Raster Surface (CUBE)12.227.69NOAA_1mComplete Coverage (Option B)H13040_SSS_1m_100SSS Mosaic1N/A100% SSSH13040_SSS_1m_200SSS Mosaic1N/A200% SSSOne (1) MBES CUBE surface and two (2) SSS mosaics comprise the total surfaces delivered with Survey H13040. To demonstrate MBES coverage requirements were met for Complete Coverage (Option B) a 1-meter CUBE surface was generated for the entire survey area. Two 1-meter SSS mosaics were submitted as GeoTIFFs to satisfy the SSS coverage requirements of 100% coverage and 200% coverage over charted feature disprovals and SSS fill-ins. In addition, a higher resolution, 25-centimeter SSS mosaic image composed of all SSS lines was submitted in the ECW (Enhanced Compressed Wavelet) format to assist with the survey review. A holiday exists in the 100% SSS coverage mosaic at the centroid of the large, three-segmented platform mentioned in H13040 DTON #2. In this case as much coverage was achieved as safe navigation practice allowed.Additional information regarding 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-17.Mean Lower Low WaterLAWMA, Amerada Pass, LA876-4227Discrete Zoning8764227.tidVerified ObservedK354KR2017rev.zdfFinalA final verified tide file was created from verified water level data from the primary tide station LAWMA, Amerada Pass, LA (876-4227) obtained from the CO-OPS website upon completion of survey operations. Discrete zoning methods were utilized to apply tide correctors in CARIS HIPS. The survey area is located within Zones 82, 115, and 154 as provided in the preliminary tidal zoning scheme included with the project SOW. Final project data are delivered with verified tides applied using a slightly altered version of the preliminary zoning file provided by CO-OPS, “K354KR2017rev.zdf.” Neither time nor magnitude multiplier changes were made to the preliminary zoning file provided by CO-OPS. However, the CO-OPS provided zoning file was found to have a minor flaw in the 6th vertex of Zone #82. It was discovered during data processing that this vertex did not fall exactly on a nearby vertex of the adjacent zone (the presumed intention of CO-OPS). The result was a long, narrow, triangular area with no zoning coverage. The non-coverage triangle had two legs roughly 11.6 kilometers long with the third leg being only about 4 meters long. OSI adjusted the Zone #82 vertex which resulted in elimination of the non-coverage area. The OSI-edited zoning file included with the project deliverables uses the same name as noted above, i.e. the file name, as delivered by CO-OPS, was retained. North American Datum of 1983 (NAD83)UTM Zone 15 NorthEnglish Turn, LA (primary), 293 kHzAngleton, TX (secondary), 301 kHzAll data products, except the S-57 Final Feature File (FFF) are referenced to Latitude/Longitude, UTM Zone 15 North. The S-57 Final Feature File, H13040_FFF.000, is referenced to the World Geodetic System Datum of 1984 (WGS 84). All MBES and SSS line and item investigation position data were acquired using an Applanix POS-MV operating in Differential GPS (DGPS) mode. The POS MV on both vessels was configured to receive USCG Differential beacon correctors from the English Turn, LA station. On one occasion during Survey H13040 USCG Differential beacon correctors from the Angleton, TX station were input to the POS MV on the R/V Ocean Explorer due to a relatively prolonged outage of the English Turn, LA beacon. In this case the poor reception is believed to be attributable to foul weather between the English Turn, LA station and the survey area. The English Turn, LA outage affected only one line (2017OE2240859_5234.HSX) and lasted from approximately 08:52 to 09:18 on 8-12-2017 (DN224). Other English Turn, LA outages did occur. However, none of the outages were of a duration long enough to trigger a change in beacon source. Rather, affected lines were either aborted or ended early when a short outage was detected. Onboard the R/V Osprey the English Turn beacon was used exclusively. Like the R/V Ocean Explorer, a few short English Turn, LA beacon outages were experienced but none of a duration sufficient to trigger a beacon change. On both vessels a secondary GPS, used to facilitate real-time horizontal control confidence checks, was supplied with correctors from the Angleton, TX beacon. Prior to and during the course of the survey the accuracy of the primary positioning system on each vessel was verified by means of a physical measurement to a horizontal control point established at the respective vessel’s base of operation. In the case of the R/V Ocean Explorer the checkpoint was established at Shell Morgan Landing in the Intracoastal Waterway. Position confidence checks for this vessel were accomplished, when practical, during fuel or weather stops. In the case of the R/V Osprey the checkpoint was established at a dock in the Quintana Canal at Cypremort Point, LA. Position confidence checks for this vessel were accomplished daily. Refer to the DAPR and HVCR for additional details. For the R/V Ocean Explorer, positioning system confidence checks were performed utilizing both DGPS signal sources mentioned above whereas the R/V Osprey utilized only the English Turn, LA beacon for positioning confidence checks.Chart comparisons were performed in CARIS HIPS/SIPS using finalized BASE surfaces, contours and selected soundings. The latest editions of the NOAA NOS Electronic Nautical Charts (ENC) were 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 ENCs used for final comparisons were downloaded on November 15, 2017 and are submitted with the survey deliverables. Local Notice to Mariners (LNM) and Notice to Mariners (NM) spanning the period beginning subsequent to the date of issuance of the final Hydrographic Project Instructions (June 21, 2017) and ending on November 15, 2017 were consulted in conjunction with the chart comparison. The following sections adhere to the Descriptive Report sounding rounding system as described in Section 5.1.2 of the HSSD. Specifically, features described below having “precision” depths are presented along with the sounding's TPU. Depth and TPU are rounded to the nearest centimeter by standard arithmetic rounding ("round half up"). 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 H13040 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. An overview of the areas of change between charted depths and H13040 surveyed soundings is shown in Figure 14. The figure displays a difference surface made by subtracting a 10-meter resolution depth surface generated from the H13040 MBES data from a 250-meter resolution depth surface interpolated from the charted ENC soundings within the project area (ENC source date noted below). Regions of shoaling are represented by positive depth differences (hot colors) and regions of deepening are represented by negative depth differences (cool colors). As evidenced by the coloring in Figure 14 a large portion of the survey area has become deeper since the last survey. The greatest areas of change (blue shading) are immediately east of two discrete migrating shoals (roughly middle-north and middle-south in Figure 14). The shoals appears to be migrating westward and a deepening trend is observed in their wake. One may expect to see a "hot spot" or a region of shoaling at the location of the migrating shoal located immediately west of the deepening spot (blue/purple) on the south side of in Figure 14. However, the ENC used in preparing this depth change analysis was downloaded on November 15, 2017. As such the shoaling trend discussed in H13040 DTON #1 has already been applied to the ENC. Accordingly, for this comparison, the newly positioned shoal does not show as a red/yellow "hot spot" in Figure 14 since, in the immediate area of the shoal, the surface-to-surface subtraction is essentially using the same data and the net change is zero. For reference, the newly surveyed shoal is immediately west of the blue-shaded area of deepening in the southern 1/3rd of Figure 14. A detailed description of each chart comparison follows.A depth difference surface overlaid on RNC 11349 provides an overview of the areas of change between charted depths and H13040 surveyed soundings.file:H13040_Figure_14_Depth_Difference_Overview.jpgUS4LA15M80000272017-09-292017-10-27falseENC US4LA15M is analogous to RNC 11349. In fact, these two chart products essentially share the same geographic footprint. Therefore, chart comparison notes entered under ENC US4LA15M apply to RNC 11349. Within the survey area ENC US4LA15M overlaps ENC US3GC03M (discussed below). As mentioned above a large portion of the survey area has shoaled. The shoaling trend is on the order of 1-meter for much of the affected area. In the northwest corner of the survey there has been little to no change. Other smaller regions of little to no change are also evident throughout the survey. The greatest magnitude of deepening, about 3.5 meters since the last survey, is east of the migrating shoals in the southern region of the survey. A 12-foot contour depth area located at approximate position 29-21-31.0N, 92-01-07.8W was disproved. The depths in this area are now greater than 16 feet. A 12-foot contour depth area located at approximate position 29-19-53.2N, 92-09-07.1W was disproved. The depths in this area are now greater than 16 feet. A 12-foot contour depth area located at approximate position 29-19-57.2N, 92-07-58.2W was disproved. The depths in this area are now greater than 15 feet. A 12-foot contour depth area located at approximate position 29-19-53.4N, 92-08-35.8W was disproved. The depths in this area are now greater than 16 feet. A 12-foot contour depth area located at approximate position 29-21-20.7N, 92-01-47.8W was disproved. The depths in this area are now greater than 15 feet. A 12-foot contour depth area located at approximate position 29-19-01.2N, 92-07-37.9W was disproved. The depths in this area are now greater than 18 feet. An 18-foot contour depth area located at approximate position 29-18-43.0N, 92-04-29.9W was disproved. The depths in this area are now greater than 20 feet. A recently altered 12-foot contour depth area at approximate position 29-19-15.2N, 92-08-53.4W does not accurately portray the full, recently sounded dataset. The southwest side of this 12-foot contour was altered (extended southwestward) to account for the shoal data included in H13040 DTON #1. However, the northeastern side of the contour was not moved southwestward to account for the deepening trend in the area (NOS/NOAA was not in possession of the full sounding set at this time). It is anticipated that this 12-foot contour will be redrawn once the data accompanying this report is incorporated to the chart update process. A 12-foot contour centered at the following general location: 29-22-22.6N, 92-08-26.3W should be redrawn based on recently surveyed soundings. The long, continuous 18-foot contour which enters the survey area in the northwest corner and ultimately exits the survey area on the southeast corner will be largely redrawn based on the recently surveyed soundings. US3GC03M458596542017-07-272017-10-13falseENC US3GC03M falls entirely within the bounds of RNC 11340. However, as seen in the figure below, despite the fact that the ENC and RNC charts are published at the same scale they do not share the same geographic boundary. Chart comparison notes entered under ENC US3GC03M apply to RNC 11340 where the two charts have overlapping coverage. The long, continuous 18-foot (3-fathom) contour which enters the survey area in the northwest corner and ultimately exits the survey area on the southeast corner will be largely redrawn based on the recently surveyed soundings. It is presumed that this contour is meant to mimic the 18-foot contour shown on ENC US4LA15M as they are closely aligned. However, as presently charted, the respective 18-foot contours are offset by as much as 1,700 meters within the survey area.An overview of ENC US3GC03M (shaded orange) superimposed on RNC 11340. file:H13040_Figure_15_ENC_US3GC03M-on-RNC11340.jpgUS4LA21M80000302017-08-252017-10-18falseData from Survey H13040 do not intersect ENC US4LA21M.No 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. If a wellhead is not found, for the purposes of disproval, a 50 m search radius shall be used following the feature disproval techniques for a complete coverage survey outlined in HSSD Section 7.3.4. Include feature in the FFF with descrp = delete." 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 visually confirmed, include in FFF with descrp=retain. If not visible, conduct a feature disproval (Section 7.3.4) and if disproved, include in FFF with descrp = delete." The addition of uncharted BSSE Wellheads in the CSF (which were, as assigned, 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 H13040, 120 features were assigned for investigation within the Composite Source File (CSF): one (1) buoy (BOYLAT), one (1) mooring facility (MORFAC), four (4) wrecks (WRECKS), twenty five (25) platforms (OSFPLF), thirty five (35) pipeline sections (PIPSOL), and fifty five (55) obstructions (OBSTRN). Of the assigned obstructions, fifty three (53) were "BSSE wellhead" obstructions. The buoy is discussed in the ATON section of this report. A mooring facility (MORFAC) charted at ENC US4LA15M position 29-20-08.01N, 92-10-05.86W (ENC US3GC03M position 29-20-08.23N, 92-10-05.93W) was disproved with 200% SSS and partial MBES coverage within a search area defined by an 80-meter radius. The ENC US4LA15M chart symbol for the MORFAC correlates well with its ENC US3GC03M and RNC counterpart. Of the four (4) assigned wrecks, all were disproved with 200% SSS and partial MBES coverage within the feature-specific search radii, i.e. 160 meters for the three (3) "PA" wrecks and 240 meters for the single (1) "PD" wreck. What appears to be a non-dangerous wreck (in relation to presently charted soundings) was detected at position 29-19-47.54N, 92-04-21.35W. This wreck-like feature is located approximately 1,734 meters northwest of the ENC-charted wreck located at 29-18-59.52N, 92-03-47.94W. The new wreck is discussed further in the Uncharted Features section of this report. For the disproved wrecks discussed herein the ENC US4LA15M wreck symbols correlate well with their RNC counterparts. However, the ENC US3GC03M wreck symbols are 100 to 400 meters distant from their ENC US4LA15M counterparts at various azimuths. See DR Section D.2.6 Platforms for information regarding the verification or disproval of the charted platforms. Of the fifty five (55) obstructions assigned for investigation all but two (2) are BSSE Wellheads. The two (2) non-BSSE Wellhead assigned obstructions include a charted SNAG and a non-specific OBSTN PA. Neither of these assigned obstructions was attributed with a known depth. Both the SNAG and the OBSTN PA were disproved with 200% SSS and partial MBES coverage within the feature-specific search radii. For the disproved non-BSSE Wellhead obstructions discussed herein the ENC US4LA15M obstruction symbols correlate well with their RNC counterparts. However, the ENC US3GC03M obstruction symbols are nearly 200 meters distant from their ENC US4LA15M counterparts at various azimuths. All BSSE Wellhead obstructions are recommended for deletion. Of the fifty three (53) BSSE Wellhead obstructions, seven (7) were coincident with verified charted platforms; however, in each case, no evidence of a wellhead aside from the verified platform was found within the disproval area centered on the CSF provided positions defined by a 50-meter search radius. All other BSSE Wellhead obstructions were either stand-alone features or were coincident with CSF-assigned platforms. Each of these remaining forty six (46) BSSE Wellhead obstructions was disproved with 200% SSS and partial MBES in a 50-meter search radius (unless a larger radius was compulsory due to the missing platform). In one case a BSSE Wellhead obstruction symbol falls at the terminus of a charted pipeline and on (near) a disproved, CSF-assigned platform that does not have a corresponding ENC/RNC platform symbol. This CSF-assigned platform is located at position 29-22-23.27N, 92-03-23.25W. For a more complete description of the well head investigations, refer to the H13040 FFF. The source indication (SORIND) attribute field was blank for the BSSE well head features submitted in the CSF; therefore, the SORIND fields are blank for the disproved well heads attributed with a description (descrp) of "Delete" in the FFF. Thirty five (35) pipeline features were assigned for investigation in the CSF. Many of the pipelines, as packaged and assigned in the CSF, extend outside the bounds of the H13040 survey area. As such, a number of the assigned pipelines are coincident with pipelines in adjacent sheets. During preliminary data processing there were thirty six (36) pipeline or potential pipeline detections identified in Survey H13040. The majority of these detections are duplicate detections, i.e. a single feature imaged on one or more adjacent tracklines. Discounting the duplicated detections, the total number of pipeline or potential pipeline detections is twenty (20). A number of these potential detections were later deemed to be something other than an exposed pipeline, e.g. a water column dolphin or a low relief escarpment. Two (2) of the twenty (20) detections, occurring in the vicinity of position 29-19-27.00N, 92-00-34.00W, are outside the boundary of H13040 and thus are "investigated" in Survey H13041. All but two pipeline detections are less than or equal to about 1-meter above the seafloor. Both pipeline detections that are about 1.0 meter above the seafloor fall within the footprint of an appropriately placed RNC chart symbol (only 32 and 45 meters from the surveyed position of the respective platforms). Therefore, none of the detections are deemed Dangers to Navigation (DTON) and all valid pipeline detections, as interpreted during late stage processing, were forwarded to the COR via e-mail on December 21, 2017 according to guidance in Section 1.7 of the HSSD regarding Non-DTON Seeps and Pipelines. A "seep" is included in the aforementioned Non-DTON pipeline notification. What is presumed to be one or more gas leaks (adjacent to a platform and at the confluence of three charted pipelines in H13040) was detected in multiple passes of MBES data. The main seep is located at approximate position 29-22-05.1N, 92-00-42.6W. The secondary seep, if it is in fact a seep, is located approximately 17 meters distant from the primary seep. Regarding the OCS-provided CSF, it should be noted that not all “assigned” features included in the CSF were addressed during the survey. This note is made in light of the Project Instructions’ directive that, “all features with attribute ‘asgnmnt’ populated with ‘Assigned’ shall be addressed in accordance with Chapter 7 of the HSSD.” The following time line and narrative are offered as an explanation thereof. The Draft Project Instructions are dated May 2, 2017 and the Draft Composite Source File (CSF) and Project Reference File (PRF) were issued on May 19, 2017. The Final Project Instructions are dated June 21, 2017, and the Final Data Package (including "final" CSF and PRF) was issued to OSI on July 5, 2017. The draft Project Instructions included seven (7) potential sheets, i.e. HXXXXX Registry Numbers. The negotiated survey effort, reflected in the Final Project Instructions and PRF include four (4) of the seven (7) original sheets. The remaining three (3) sheets are depicted as “unassigned” in the figure included with the Final Project Instructions. However, the Final CSF (file date 5-19-2017) does not reflect the reduction in sheets mentioned above. As such, there are a number of Final CSF “assigned” features that fall well outside of the four surveyed sheets. OSI’s assumption that the CSF “assigned” features falling within the three “unassigned” sheets need not be addressed was confirmed in correspondence with the COR (see Descriptive Reports Appendix II, Correspondence). For clarity the CSF “assigned” features that fall within the three “unassigned” sheets mentioned above are not included in the FFFs. Prior to this year, 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 H13040. Of the relatively few SSS contacts chosen most were either fish (chosen independent of the mass fish targeting scheme described in the DAPR) or features of insignificant height. All noteworthy new obstructions were surveyed with Complete Coverage MBES. In consideration of each obstruction's nearby soundings or proximity to existing platforms, none of the new obstructions warrant DTON notification. A feature located at position 29-21-15.53N, 92-09-34.66W with a least depth of 14 feet (4.20 m, ±0.40 TPU) is a nondescript mound located over 500 meters from the nearest charted feature. The 14-foot "nondescript mound" feature is presently surrounded by 14-foot and 15-foot charted soundings (Figure 16) Another feature appears to be a non-dangerous wreck-like item detected at position 29-19-47.54N, 92-04-21.35W with a least depth of 16 feet (5.01 m, ±0.40 TPU). As mentioned above this wreck was deemed "non-dangerous" in light of the nearby, presently charted soundings. This wreck-like feature is located approximately 1,734 meters northwest of the ENC-charted "Wreck PD" located at 29-18-59.521N, 92-03-47.941W. The 16-foot wreck-like feature is presently surrounded by 14-foot, 15-foot, and 17-foot charted soundings (Figure 17). This wreck-like feature does not meet the criteria for sounding designation given that it is less than 1.0 meter proud of the seafloor. However, in this case, hydrographer's discretion drove the decision to designate the shoal sounding on the feature. This feature is attributed as a "dangerous" wreck in the FFF due to its relative depth as compared to the recently surveyed soundings. A feature located at position 29-19-35.25N, 92-05-25.49W with a least depth of 15 feet (4.69 mm, ±0.40 TPU) has the shape of a large Danforth-type anchor (this is not to suggest that the feature is an anchor). The 15-foot feature is presently surrounded by 15-foot, 16-foot, and 17-foot charted soundings (Figure 18). Within Survey H13040 there are at least two noteworthy exposed pipeline features, both having a nominal height of 1.0 meter proud of the seafloor. In both cases these "pipe arch" obstructions are within the footprint of a nearby RNC-charted platform. In neither case is the pipe arch cause for undue concern in light of the nearby, presently charted soundings. The two pipe arches are also discussed in the Non-DTON Seep and Pipeline Report. This report was forwarded to the COR on December 21, 2017 and is included in H13040 DR Appendix II. The position and depths of the two noteworthy pipe arches follows: Pipe Arch #1 (Non-DTON Seep and Pipeline Report Image Key #3) 29-22-03.18N, 92-01-28.18W, 14 feet (4.34 m, ±0.40 TPU). Pipe Arch #2 (Non-DTON Seep and Pipeline Report Image Key # 12) 29-22-05.35N, 92-00-41.92W, 12 feet (3.74 m, ±0.40 TPU). In close proximity to the second listed pipe arch (and charted platform discussed above) there exists a region of disturbed seafloor surrounding the platform. The disturbance is likely associated with construction and/or sediment movement associated with the Non-DTON seeps included in the Non-DTON Seep and Pipeline Report. The shoalest mound in the disturbed area is located at position 29-22-04.96N, 92-00-42.12W and has a least depth of 10 feet (3.10 m, ±0.40 TPU). Like the pipe arch, the disturbed seafloor is entirely within the footprint of the RNC-charted platform. Figure 19 shows the spatial relationship between the two seeps, H13040 pipe arch #2, the surveyed platform, and the shoalest disturbed bottom mound. There exists a pipeline arch at position 29-22-03.18N, 92-01-28.18W that, for a number of reasons, does not meet the criteria for DTON notification. Nor does this pipeline arch meet the criteria for sounding designation given that it is just less than 1.0 meter proud of the seafloor. In this case hydrographer's discretion drove the decision to designate the shoal sounding on the pipe arch. See H13040_FFF.000 for additional information.A 14-foot "nondescript mound" feature is represented in CARIS HIPS Subset Editor 3D with the soundings colored by depth (left) and in the SIPS waterfall SSS imagery (right).file:H13040_Figure_16_14-foot_Feature.jpgA 16-foot wreck-like feature is represented in CARIS HIPS Subset Editor 3D with the soundings colored by depth (left) and in the SIPS waterfall SSS imagery (right).file:H13040_Figure_17_16-foot_Wreck_Feature.jpgA 15-foot anchor-like feature is represented in CARIS HIPS Subset Editor 3D with the soundings colored by depth (left) and shown as a CARIS depth surface (right). file:H13040_Figure_18_Anchor-Like_Feature.jpgA disturbed seafloor area mound is represented in relation to other H13040 features of interest in CARIS HIPS Subset Editor 3D with the soundings colored by depth. file:H13040_Figure_19_Disturbed%20Seafloor_Mound.jpgThe methods employed in conducting the Shoal and Hazard Features analysis are the same as described above for the Chart Comparison discussion. In Survey H13040 the only hazardous features surveyed are shoal features associated with what appears to be two large scale mobile bedforms. This is not surprising given that a large portion of the survey falls within the sea area/named water area known as "Tiger Shoal." In fact, the two shoal areas of note can said to be part of Tiger Shoal. The first shoal area of note was the subject of "H13040_DtoN_1_Shoal.000" submitted to AHB on September 21, 2017. The general location of this shoal is 29-19-11.2N, 92-09-09.0W. This shoal appears to have migrated around one half mile to the west from its previously charted position. Information included in H13040 DTON #1 has since been used to update contours and soundings on ENC US4LA15M and RNC 11349. The change/public notification was first made via LNM 41/17 (October 11, 2017). LNM 41/17 called for deletion one (1) sounding and addition of seven (7) new soundings in the area. The deletion/addition of soundings was in reference to the 46th Edition of RNC 11349. The 47th Edition of RNC 11349 was published on October 1, 2017 and includes the changes referenced herein as well as alteration of one charted contour and the addition of one charted contour in the vicinity of the DTON soundings. LNM 45/17 (November 8, 2017) provides notification of the 47th Edition of RNC 11349. The updated ENC US4LA15M was issued on October 27, 2017. This shoal is included in the ENC US4LA15M discussion (above) in reference to a "recently altered 12-foot contour depth area." The second shoal area of note is on the northern border of H13040 at the following general location: 29-22-22.6N, 92-08-26.3W. This shoal did not warrant a DTON submittal as the shoal depths are generally in keeping with the charted soundings of the area and the shoal is generally bound by the existing 12-foot contour. It is anticipated however that the 12-foot contour will be redrawn as there is a deepening trend in this area (as well as across the entire sheet). Two 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.Ten (10) bottom samples were acquired in close proximity to the recommended positions included in the PRF provided with the OPR-K354-KR-17 Project Instructions. Both vessels shared responsibility for sediment sample acquisition. On each vessel 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. In general, sediment was found to be in keeping with anticipated nearshore, coastal Louisiana sediments and as-charted conditions. Specifically, sediment within Survey H13040 ranges in consistency from soft mud to stiff sand with some samples containing shell hash.Shoreline was not assigned in the Hydrographic Survey Project Instructions or Statement of Work.Prior survey data exist for this survey area. However, with the exception of the assigned junction surveys, prior data were not investigated.One ATON exists within Survey H13040. The CSF-"assigned" buoy, red nun #2, is located near the southwest end of Tiger Shoal. The buoy was visually observed at its approximate charted position. The ENC-charted and CSF-defined position of the buoy is 29-19-24.570N, 92-09-29.346W. However, the Light List, corrected to Week 45/17 (November 8, 2017) suggests the buoy position is 29-19-24.72N, 92-09-29.82W. The MBES as-surveyed position of the buoy block is 29-19-24.40N, 92-09-28.15W. The buoy block's as-surveyed position is approximately 33 meters ESE of the ENC-charted position. It is assumed that the "intended purpose" of this buoy, as placed and charted, is to mark the western edge of the shoal feature previously charted at approximate position 29-19-19.5N, 92-08-51.7W. As discussed below, the shoal has migrated west approximately one half of a nautical mile. Assuming that the nun's intended purpose is to mark the western edge of the shoal this indicates that the buoy should be moved west to account for the shifting shoal. However, a Wreck PA symbol is presently charted about 800 meters (0.4 nautical miles) to the northwest of the red nun. A vessel returning from sea may use this buoy as a waypoint for entering the Southwest Pass safety fairway. Given this scenario, shifting the buoy west to accommodate the shoal migration would serve to put the Wreck PA symbol in the natural approach to the safety fairway which, to a mariner, may be a confusing scenario. As noted in the Charted Features section above, all of the charted wrecks in Survey H13040 were disproved. Therefore, it is recommended that the red nun is moved west to accommodate the shifting shoal once the Wreck PA symbol located at position 29-19-42.28N, 92-09-51.35W is removed from the chart products. No overhead features exist for this survey.As discussed above, thirty five (35) charted pipelines (PIPSOL) are located within Survey H13040. On RNC 11349, only magenta pipeline symbols are shown. This symbol represents supply pipelines for oil, gas, chemicals, or water, according to U.S. Chart No. 1: Symbols, Abbreviations and Terms used on Paper and Electronic Navigational Charts. None of the Information contained within ENC US4LA15M or the CSF refute the RNC symbolism. None of the charted pipelines have a buried depth value (BURDEP). Six (6) of the ENC charted pipelines have a status of "disused." The majority of the charted pipelines were not visible in the SSS or MBES data. All ENC pipelines within the survey area have a RNC counterpart. All CSF assigned pipelines are represented (within the survey area) in ENC US4LA15M as well as the the large scale RNC of the area, RNC 11349. The pipelines are not represented on ENC US3GC03M. To further the submarine features discussion an alternate pipeline information source was consulted. The consult includes review of information contained in a pipeline shape file (.SHP) downloaded from the Bureau of Ocean Energy Management (BOEM) on November 30, 2017. Prior to including the BOEM shape file in this analysis, the portion of the shape file that intersects with the OPR-K354-KR-17 project area was reprojected to UTM, Zone 15N, NAD83 and saved as a .DXF file. In CARIS HIPS/SIPS the BOEM pipeline .DXF file was then visually compared to the charted pipelines within the project area to identify any potentially uncharted BOEM pipelines. All but one charted pipeline has a BOEM pipeline counterpart. However, the results of the analysis suggest that there may be over a dozen uncharted BOEM-listed pipe segments within Survey H13040. The majority of potentially uncharted BOEM pipe segments mentioned above fall within a pipeline confluence area at approximate position 29-20-06.8N, 92-00-42.6W. At this location there already exists a tangle of charted pipelines and a large, sprawling platform. Therefore, the addition of uncharted BOEM pipelines in this area would not practically serve the mariner/chart user. There are three instances of more distinct, stand-alone BOEM pipelines, not being represented on the ENC/RNC chart products. The general position of these uncharted BOEM pipe segments is as follows: 29-19-23.9N, 92-11-22.9W, 29-21-27.6N, 92-07-52.4W, and 29-20-16.6N, 92-03-27.1W. With two exceptions, no evidence of the uncharted pipelines was detected in the MBES or SSS data. However, all of the three uncharted BOEM pipelines discussed herein intersect either a charted pipeline or platform. In two cases there is evidence of the existence of an uncharted BOEM pipeline intersecting a charted pipeline. In these cases a linear feature, proud of the seafloor, is observed to cross a charted pipeline. In both cases the linear feature falls on, and is oriented identically to the BOEM-defined pipeline. These instances are believed to be pipe crossings where the BOEM-defined pipeline is laid over the existing charted pipeline. These interpreted pipe crossings occur at the following positions: 29-22-01.9N, 92-07-16.3W and 29-19-57.8N, 92-09-27.4W. In one case an ENC/RNC charted pipeline, located in the vicinity of position 29-18-52.2N, 92-10-11.9W, does not have a BOEM pipeline counterpart. Uncharted BOEM pipelines as well as the charted pipeline without a BOEM pipeline counterpart are displayed in Figure 20. The shape file, “ppl_arcs.shp” (contained within ppl_arcs.zip) and re-projected .DXF file, “BOEM_Pipelines_UTM_15N_NAD83_Meters.dxf” are included with the digital deliverables along with the RNC/ENC charts considered in the chart comparison. BOEM pipeline data were obtained at the following web address: https://www.data.boem.gov/Main/Mapping.aspxBOEM-defined pipelines that are not charted are highlighted in yellow in reference to RNC 11349. The charted pipeline without a BOEM counterpart is highlighted in blue. Survey H13040 sheet limits are shown in black. file:H13040_Figure_20_BOEM%20Pipeline%20Analysis.jpgTwenty five (25) platforms (OSFPLF) were assigned for investigation in the CSF for Survey H13040. Of these, only 24 platforms exist on ENC US4LA15M and only 23 (or 24, see discussion below) platforms exist on RNC11349. There are no platforms depicted on ENC US3GC03M. The instance of the "missing" ENC platform occurs at the CSF platform positioned at 29-22-23.27N, 92-03-23.20W. Of the two instances where RNC 11349 appears to have missing platforms, one instance occurs at the aforementioned location. The second possible instance of a "missing" RNC platform is at approximate position 29-19-23.4N, 92-09-26.7W where what looks like only one RNC platform is charted but two ENC/CSF platforms exist in close proximity to one another. In this case the intention may have been to depict two RNC platforms but the separation between platform symbols is so small as to be practically indistinguishable as two distinct symbols. Of the twenty five (25) assigned platforms, seven (7) platforms were found to exist. All existing platforms were surveyed in close proximity to the CSF/ENC defined locations, i.e. a distance of less than 80 meters from the CSF/ENC defined position (80 m is equivalent to 2 mm at a scale of 1:40,000). However, all but one (1) of the surveyed platforms are greater than or equal to 10 meters from the CSF listed position. Therefore, all but one (1) of the CSF platforms that were confirmed via the survey were "deleted" in the FFF and "new" platforms were established at the surveyed locations. One (1) surveyed platform is attributed with "retain." All other CSF-assigned platforms are recommended for deletion as they were disproved visually at the surface and with 200% SSS coverage and partial MBES coverage within the disproval area defined by an 80-meter radius (or larger) centered on the CSF provided platform position. Images are included in the FFF for all verified platforms. The existing platforms are as follows (positions per CSF): 29-19-51.499920N, 92-09-52.692120W 29-19-23.534040N, 92-05-02.399280W 29-20-39.530040N, 92-03-13.686120W 29-22-03.143640N, 92-01-29.196120W 29-22-03.949680N, 92-00-42.231960W 29-20-03.544800N, 92-00-44.354520W 29-19-35.814360N, 92-00-41.994720W One of the platforms with coordinates listed above is a large, three-segmented, sprawling platform with the main structures connected by catwalks (See Figure 21). The two major structures, oriented nominally south-north, when measured center-to-center, are separated by nearly 100 meters. As such, it is recommended in H13040 DTON #2 that, at a minimum, an additional platform symbol be added to both ENC US4LA15M and RNC 11349. The existing, appropriately placed, ENC/CSF platform symbol is located at position 29-20-03.54N, 92-00-44.35W (recommended "new" at 29-20-04.75N, 92-00-44.31W). This position describes the southern structure. The new platform symbol could be added at the nominal center of the northern structure at position 29-20-07.79N, 92-00-44.57W. It is noted that BOEM-listed platform positions fall on both the charted platform position and the recommend platform symbol addition discussed in this paragraph. BOEM platforms are described below. To further the offshore platform discussion an alternate platform information source was consulted. The consult includes review of information contained in a platform shape file (.SHP) downloaded from the Bureau of Ocean Energy Management (BOEM) on November 30, 2017. Prior to including the BOEM shape file in this analysis, the portion of the shape file that intersects with the OPR-K354-KR-17 project area was reprojected to UTM, Zone 15N, NAD83 and saved as a .DXF file. In CARIS HIPS/SIPS the BOEM platform .DXF file was then visually compared to the charted platforms within the project area to identify any potentially uncharted BOEM platforms. Given that only seven (7) CSF-assigned platforms were found during the survey, it follows that there were no uncharted platforms within the bounds of the survey limits (except the "new" platform section recommended for charting above). The majority of BOEM-listed platforms coincide with ENC/CSF-charted platforms. However, there are thirteen (13) BOEM-listed platforms that do not have an ENC/CSF counterpart. Of these BOEM platforms, nine (9) are positioned at the end of, or over charted pipelines. One of the BOEM platforms is located at the position of the "missing" ENC/RNC platform mentioned above at CSF-platform position 29-22-23.27N, 92-03-23.20W. Notice to Mariners 41/17 (October 14, 2017) calls for deletion of a platform from RNC 11349. RNC 11349 coincides with ENC US4LA15M. The position of the recommended deletion is as follows: 29-22-23N 92-03-23W. Neither the ENC nor the RNC have a platform symbol at (or near) this position. See the FFF for additional information regarding the disproved and verified charted platforms. The shape file, “platforms.shp” (contained within platforms.zip) and re-projected .DXF file, “BOEM_Platforms_UTM_15N_NAD83_Meters.dxf” are included with the digital deliverables along with the RNC/ENC charts considered in the chart comparison. BOEM platform data were obtained at the following web address: https://www.data.boem.gov/Main/Mapping.aspxLarge, three-segmented platform discussed in Section D.6. above. In this photo the smallest of the main structures is not visible as it is masked by one of the foreground structures.file:H13040_Figure_21_Large-Multisegmented%20Platform.jpgNo ferry routes or terminals exist for this survey.As noted above there is evidence of long term sediment transport within the survey area, i.e. the shoal soundings of Tiger Shoal appear to be migrating westward. During the period of the survey, evidence of short term sediment movement was observed. Figure 22 depicts a portion of the depth surface from the western side of Survey H13040. Water depth in this area is around 6.2 meters. Featured in the image are MBES data acquired on 80-meter mainscheme lines from DN 222 and 40-meter split lines from DN 264. Even at 5x vertical exaggeration the mainscheme lines on the surface appears smooth while the split lines show "sediment wave" relief on the order of 15 centimeters. Sediment grabs acquired in the vicinity of this example were described as "stiff sandy mud." It is assumed that the change in bottom character between DN 222 and DN 264 is largely attributable to the relatively close passage of Hurricane Harvey (around DN 237-242). Example of sediment transport in H13040 which occurred over a relatively short period of time. file:H13040_Figure_22_Sediment%20Transport_Discussion.jpgExcept for the presence of temporary jackup barges attending to platform maintenance, no other construction or dredging was observed within the survey limits at the time of data acquisition. Editing of Jackup Barge FootprintsIn one instance a jackup barge visited an area within H13040 at a time between the acquisition of mainscheme MBES lines and investigation MBES lines. Therefore, what was first surveyed as a relatively flat seafloor was later found to have three large depressions. In the case of overlapping data in the area of the jackup barge footprints the older data (DN223) was rejected and the newer data (DN 261) was retained (Figure 23). The jackup barge footprints are found at approximate position 29-20-41.5N, 92-03-15.1W.Jackup barge footprints shown with rejected soundings displayed (colored grey left panel) and with rejected soundings removed (right panel). file:H13040_Figure_23_Jackup_Footprints.jpgMarine Mammal ObservationsPer direction in Section 1.5 of the HSSD all personnel aboard the survey vessel used during Project OPR-K354-KR-17 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-17 survey area the Coast Pilot Report, included with the July 6, 2017 Final Data Package, states that, "there are no paragraphs included in the U.S. Coast Pilot 5 that describe this area and thus, there are no investigation items to be listed." The survey area considered in the Coast Pilot Report does not exactly match the area ultimately surveyed. However, the Report's "no-investigations" statement still applies to the area actually surveyed. Furthermore, the Hydrographic Survey Project Instructions contained only general guidance regarding the Coast Pilot. As such OSI was not able to “respond to each question posed in the Coast Pilot Field Report” as mentioned in Section 8.1.3 of the HSSD. 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 - 45th Edition, 2017 updated through 12-October-2017, Mississippi River to Sabine Pass. Within the Coast Pilot Edition mentioned above there are no specific, detailed, relevant entries concerning the assigned H13040 survey area. Rather, only entries of a general nature are mentioned 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 OSI's general review attempts to address as most entries were 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 meet or exceed requirements as set forth in the NOS Hydrographic Surveys and Specifications 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 Party2018-01-31Data Acquisition and Processing Report2018-01-19Horizontal and Vertical Control Report2018-01-19