OPR-K354-KR-17Louisiana CoastGulf of MexicoOceans Surveys, Inc.H130412East Tiger 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. 29.462290592.01363429.294934694491.8806555556Survey 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. Inside the 4-meter contour, except in investigation or disproval areas, Set Line Spacing MBES was acquired on a 200 meter offset lineplan. 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 44.75 square nautical miles (Figure 1).Survey H13041 MBES coverage overlaid on RNC 11340.file:H13041_Figure_1_Coverage_Graphic.jpgR/V Ocean Explorer "OE"00000681.10040.650R/V Osprey "SB"0238.5500.700121.05043.7700238.5500.700802.15084.4208.11000044.752017-08-052017-08-062017-08-212017-08-222017-08-232017-08-242017-09-012017-09-022018-09-032017-09-042017-09-082017-09-092017-09-112017-09-122017-09-132017-09-142017-09-162017-09-172017-09-182017-09-222017-09-232017-09-262017-09-272017-10-12The lineal nautical miles (LNM) for MBES-only development and fill in lines were included under the heading "Mainscheme MBES" and the LNM for SSS-only fill in lines were included under the heading "Mainscheme SSS" in Table 2, Hydrographic Survey Statistics. The overall crossline/mainscheme MBES line percentage (8.1%) is based on combined coverage types, e.g. Complete Coverage and Set Line Spacing. If considered independently the Complete Coverage crossline percentage is 5.0% and the Set Line Spacing crossline percentage is 19.2%. 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 8125MBESODIM 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 84.42 nm of crossline data were acquired August 5 (DN217), August 6, 2017 (DN 218), August 24, 2017 (DN 236) and September 4, 2017 (DN247). Of these data, 40.65 nm from DN 217 and DN 218 apply to the deeper water, Complete Coverage dataset (acquired by the R/V Ocean Explorer). The 43.77 nm of crossline data acquired on DN 236 and DN 247 apply to the shallow water Set Line Spacing dataset (acquired by the R/V Osprey). Complete Coverage crossline mileage equaled 5.0%. Set Line Spacing crossline mileage equaled 19.2%. Crosslines were run nominally perpendicular to their coverage type-specific mainscheme lines (Figure 2). 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 various difference surfaces, generated in CARIS HIPS. In all cases the depth layer of a 1-meter CUBE surface was used. The following crossline comparisons were undertaken: 1) Complete Coverage MBES mainscheme vs. Complete Coverage MBES crosslines. These data were generally acquired by the R/V Ocean Explorer. 2) Set Line Spacing MBES mainscheme vs. Set Line Spacing MBES crosslines. These data generally acquired by the R/V Osprey. 3) R/V Ocean Explorer MBES mainscheme & crosslines vs. R/V Osprey MBES mainscheme and crosslines. This test compares data acquired by the R/V Ocean Explorer to data acquired by the R/V Osprey. There is not a regular pattern of overlap between the two vessels. Rather, the overlaps primarily occur throughout the southern 2/3 of the survey where R/V Ocean Explorer data were later supplemented with additional MBES data acquired by the R/V Osprey. Despite the fact that there was not a deliberate attempt to create overlap for the purposes of this analysis, over 350,000 individual 1-meter comparison cells exist. The relatively large amount of overlap cells is due to the fact that much of the comparison data is derived from overlapping parallel lines. In each case the crossline analysis results demonstrate good to excellent agreement between crossline soundings and mainscheme soundings. The following numbered list (keyed to the comparison surface description numbered list above) summarize the maximum depth differences and average depth differences of the respective comparisons: 1) Maximum depth difference 0.51 meters, average depth difference 0.12 meters. Depth differences, including the maximum difference of 0.51 meters, are mostly attributable to tide offsets. However, over 40 days elapsed between acquisition of the crosslines and some of the worst mainscheme line agreement nodes. During this period Hurricane Harvey passed relatively close to the survey area. As such some discrepancy between the early-survey crosslines and late-survey mainscheme lines is expected. 2) Maximum depth difference 0.26 meters, average depth difference 0.02 meters. In contrast to the Complete Coverage analysis above, the majority of crosslines considered in this case (along with all set line spacing mainscheme lines) were acquired after Hurricane Harvey passed. 3) Maximum depth difference 0.72 meters, average depth difference 0.05 meters. The maximum difference of 0.72 meters occurs at approximate position 29-20-55.63N, 91-59-19.27W at the location of a platform with nearby jackup barge footprints. In this case, DGPS positioning accuracy (+/- 1-meter) is responsible for enough of a shift in vessel/day-specific sounding points to cause a relatively large difference in the 1-meter comparison grid cells, i.e. the crossline statistics consider depths from the bottom of a jackup barge footprint (from one dataset) and the top of the berm from the same footprint (from another dataset) within the same 1-meter comparison cell. Discounting this anomalous region (and a few other comparable feature-specific instances) the vessels compare quite well. The allowable TVU for the range of water depths within Survey H13041 is 0.50 to 0.51 meters. Figure 3 is a histogram showing the distribution of depth differences for all comparison grid cells considered in comparison case #1 noted above. The total number of 1-meter comparison cells equaled 409,916. Of 409,916 possible comparison cells, 377,577 or 92.11% of the cells include crossline and mainscheme soundings that match within +/- 25 centimeters. Figure 4 is a histogram showing the distribution of depth differences for all comparison grid cells considered in comparison case #2 noted above. The total number of 1-meter comparison cells equaled 44,118. Of 44,118 possible comparison cells, 44,115 or 99.99% of the cells include crossline and mainscheme soundings that match within +/- 25 centimeters. Figure 5 is a histogram showing the distribution of depth differences for all comparison grid cells considered in comparison case #3 noted above. The total number of 1-meter comparison cells equaled 359,668. Of 359,668 possible comparison cells, 350,337 or 97.41% of the cells include crossline and mainscheme soundings that match within +/- 25 centimeters.An overview of the crossline layout on a 1-meter surface. In this figure the combined Complete Coverage/Set Line Spacing mainscheme MBES surface is colored by depth. The Complete Coverage crosslines are colored black and the Set Line Spacing crosslines are colored blue. RNC 11349 is visible in the background.file:H13041_Figure_2_Crosslines.jpgThe graph shows a frequency distribution of the depth differences between the H13041 Complete Coverage crossline data and the H13041 Complete Coverage mainscheme MBES data. Statistics from the depth difference sample set are displayed above the graph.file:H13041_Figure_3_CC_XL.jpgThe graph shows a frequency distribution of the depth differences between the H13041 Set Line Spacing crossline data and the H13041 Set Line Spacing mainscheme MBES data. Statistics from the depth difference sample set are displayed above the graph.file:H13041_Figure_4_SLS_XL.jpgThe graph shows a frequency distribution of the depth differences between H13041 MBES data collected by R/V Ocean Explorer vs. MBES data collected by R/V Osprey. Statistics from the depth difference sample set are displayed above the graph.file:H13041_Figure_5_OE_vs_SB_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 H13041 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. In anticipation of shallow conditions in the north end of the survey area the Project Instructions requested Complete Coverage in regions deeper than 4-meters and Set Line Spacing coverage in regions shoaler than 4-meters. This assignment would normally result in production of two delivered surfaces: a 1-meter Complete Coverage surface and a 4-meter Set Line Spacing surface. After consultation with the COR and AHB personnel it was agreed that the entire survey area would be presented as a single, 1-meter surface. As such one (1) MBES CUBE (Combined Uncertainty and Bathymetric Estimator) surface was delivered along with Survey H13041: "H13041_MB_1m_MLLW_Final." The 1-meter surface is intended to satisfy coverage and sounding density requirements for both of the assigned coverage type-specific regions within the survey. The TVU QC values discussed below are calculated using the comprehensive 1-meter surface. Results from the TVU QC indicate that 99.99% of the nodes from the submitted surface meet IHO Order 1 uncertainty specifications, i.e. the ratio values of nearly all the nodes are less than -1. Of the 30,068,726 nodes considered, 15 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 two (2) contemporary surveys junction with Survey H13041. Figure 6 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 H13041 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:H13041_Figure_6_Junctions.jpgH11670200002007C&CNWSurvey H11670, a MBES/SSS survey conducted by C&C in 2007-2008, overlaps the northern half of the western border of H13041. Survey H11670 was run with the intention of achieving 200% SSS coverage. In the overlap area of Survey H13041 both 100% SSS (with concurrent MBES) and Set Line Spacing MBES-only were acquired. The majority of the overlap area is in the H13041 Set Line Spacing region. As such, each survey's MBES coverage is essentially "skunk stripe coverage." The mainscheme line plan orientation for each survey type is variable. The common border length is approximately 9,000 meters. The junction area between the surveys is relatively sparse. The overlap between surveys is on the order of 100-150 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_5of6.bag." To conduct the junction comparison a 2-meter CUBE surface was generated from the entire MBES data set for Survey H13041, "H13041_MB_2m_MLLW." In CARIS HIPS, depths from the "H11670_2m_MLLW_1of6" and "H11670_2m_MLLW_5of6" BAGs were subtracted from the depths in the "H13041_MB_2m_MLLW" CUBE surface using the CARIS HIPS Difference Surface function. A histogram of the differences is shown in Figure 7. The total number of 2-meter comparison cells equaled 5,924. Of 5,924 possible comparison cells, 5,647 or 95.32% of the cells include survey-specific soundings that match within +/- 25 centimeters. 99.26% of junction comparison cells have a difference < 0.71 meters. With a few noteworthy exceptions, depths from the H13041 survey show good agreement with depths from the H11670 survey. Depth discrepancies equaled 0.76 centimeters or less. However the mean difference is only 4 centimeters. On average, Survey H11670 depths were deeper than H13041 depths. The largest depth discrepancies occur in the vicinity of position 29-25-41.68N, 92-00-21.46W. In this region of overlap the contemporary soundings and the junction soundings disagree by as much as 0.76 meters. In this same general area mainscheme and crossline soundings from the junction survey disagree by as much as 0.6 meters whereas soundings from the contemporary survey show fairly good agreement (<20 cm) with the nearest junction survey's crossline. In summary, it is surmised that the junction survey used a flawed tide source to correct mainscheme soundings in the area of overlap discussed herein (see Figure 8).Surface-to-surface difference histogram comparing Survey H13041 to H11670.file:H13041_Figure_7_H11670_Junction.jpgJunction area depth disparity area where contemporary soundings compare favorably with the junction survey crossline soundings but compare poorly with the junction survey mainscheme soundings. Soundings from each survey are presented using a similar color palette which allows visualization of the sounding disparity discussed above.file:H13041_Figure_8_H11670_Junction_Disparity.jpgH11990200002008C&CNSurvey H11990, a MBES/SSS survey conducted by C&C in 2008-2011, overlaps the northern border of H13041. Survey H11990 was run with the intention of achieving 200% SSS with concurrent MBES and, in the overlap area, Survey H13041 was run on a MBES-only 200-meter Set Line Spacing plan. As such, each survey's MBES coverage is essentially "skunk stripe coverage." In the overlap area the mainscheme line plan for Survey H11990 has various orientations. As a result the Survey H13041 Set Line Spacing line plan, oriented nominally south-north, meets the junction survey at various intersection angles. The common border length is approximately 18,000 meters. The junction area between the surveys is relatively sparse. The combined overlap of the adjacent survey areas is around 100-250 meters. Depth data for Survey H11990 were downloaded from the National Geophysical Data Center (NGDC) website (http://www.ngdc.noaa.gov) in the form of 1-meter resolution Bathymetric Attributed Grid (BAG)s, "H11990_MB_1m_MLLW_2of7.bag," "H11990_MB_1m_MLLW_3of7.bag," and "H11990_MB_1m_MLLW_4of7.bag." To conduct the junction comparison a 1-meter CUBE surface was generated for the overlapping MBES data set for Survey H13041, "H13041_North_MB_1m_MLLW." In CARIS HIPS, depths from the three H11990_1m_MLLW BAGs were subtracted from the depths in the "H13041_North_MB_1m_MLLW" CUBE surface using the CARIS HIPS Difference Surface function. A histogram of the differences is shown in Figure 9. Depths from the H13041 survey show relatively poor agreement with depths from the H11990 survey. Depth discrepancies equaled 1.15 meters or less with a mean difference of 0.48 meters. Unlike other junction analyses presented along with Project OPR-KR354-KR-17, the maximum difference in this junction analysis does not occur at a discrete feature or seafloor anomaly. Rather, the maximum junction depth disparity is one of many differences in the area with nearly the same magnitude. Survey H11990 depths were overwhelmingly deeper than H13041 depths. Given that the contemporary survey's mainscheme/crossline agreement is consistently tight in the region of the junction and that the junction analysis shows a consistent offset it follows that the consistent offset could be due to application of tide correctors, and/or sediment transport in the H13041 survey area since the 2008-2011 survey. It is noted that in the northwest corner of Survey H13041 there is a consistent offset on the order of 0.3 meters in the area of overlap between junction Surveys H11990 and H11670 (discussed above). Based on this observation it appears that there may have been some trouble with internal consistency of the junction surveys which would likely point to a tide application issue. Most (90.59%) junction comparison cells have a difference < 0.71 meters.Surface-to-surface difference histogram comparing Survey H13041 to H11990.file:H13041_Figure_9_H11990_Junction.jpgH13040400002017Oceans Surveys, Inc.WThe approximate overlap between the bathymetric data from contemporary Surveys H13041 and H13040 was approximately 300 meters (within Complete Coverage areas) along a common border of approximately 8,000 meters. Both surveys were acquired to meet 100% SSS Coverage over the length of the common border. Given that the respective line plans meet at an obtuse angle there is a fair amount of overlapping data despite the skunk stripe nature of Complete Coverage MBES coverage. Depths from 1-meter BASE surfaces compiled from the MBES data from each survey, "H13041_MB_1m_MLLW" and "H13040_MB_1m_MLLW," were compared using the CARIS HIPS Difference Surface function. A histogram of the differences is shown in Figure 10. Depths from the H13041 survey show good agreement with the depths from the H13040 survey. Depth discrepancies generally equaled 25 centimeters or less with a mean difference of 2 centimeters. All (100%) junction comparison cells have a difference < 0.71 meters. Surface-to-surface difference histogram comparing Survey H13041 to H13040.file:H13041_Figure_10_H13040_Junction.jpgH13042400002017Oceans Surveys, Inc.SEThe approximate overlap between the bathymetric data from contemporary Surveys H13041 and H13042 was approximately 300 meters along a common border of approximately 9,400 meters. Both surveys were acquired to meet 100% SSS Coverage over much of the length of the common border and Set Line Spacing coverage just at the northern end of the common border. Given that the respective line plans meet at an obtuse angle there is a fair amount of overlapping data despite the skunk stripe nature of Complete Coverage MBES coverage. Depths from 1-meter BASE surfaces compiled from the MBES data from each survey, "H13041_MB_1m_MLLW" and "H13042_MB_1m_MLLW," were compared using the CARIS HIPS Difference Surface function. A histogram of the differences is shown in Figure 11. Depths from the H13041 survey show good agreement with the depths from the H13042 survey. Depth discrepancies generally equaled 20 centimeters or less with a mean difference of 4 centimeters. All (100%) of junction comparison cells have a difference < 0.71 meters. Surface-to-surface difference histogram comparing Survey H13041 to H13042.file:H13041_Figure_11_H13042_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 Project OPR-K354-KR-17, 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.SSS RefractionDynamic sound speed changes affected the SSS imagery at times, causing refraction in the outer ranges of the SSS swath (Figure 12). 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 at the 30-meter range of a survey line acquired with the fixed-mount 4125 SSS.file:H13041_Figure_12_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 13). 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 palette. 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:H13041_Figure_13_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 H13041. 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 H13041, 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 14 highlights a portion of the survey area where a tide offset was noted between a crossline from DN 217 and mainscheme data from DN 233, DN 234, and DN 265 . The left image shows a subset window displayed over the Standard Deviation layer from the H13041 1-meter CUBE surface. The yellow 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 (bright green) and some of the survey lines from DN 233(purple), DN 234 (olive green), and DN 275 (mustard yellow) . Depths and distances are in meters.file:H13041_Figure_14_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 15-17). 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. Within the Complete Coverage portion of the survey area alone over 17,000 fish contacts were chosen in Survey H13042.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:H13041_Figure_15_Fish-MBES-SSS.jpgSSS image showing a large "fish cloud" on the starboard channel.file:H13041_Figure_16_Fish_Clouds.jpgAn example of dolphins as they appear 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:H13041_Figure_17_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 H13041 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 depths 4-meters and greater, i.e. Complete Coverage, Option B as defined in Section 5.2.2.3 of the HSSD 2017. Inside the 4-meter contour Set Line Spacing MBES coverage without SSS was acquired. For all disprovals either 200% SSS or Complete Coverage MBES was achieved. All depths within Survey H13041 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.DensityAs mentioned above a single 1-meter surface was delivered for this survey. To 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 submitted CUBE surface. The HSSD states that at least 95% of the surface nodes shall be populated with at least 5 soundings (for either a Complete Coverage (Option B) 1-meter surface or a Set Line Spacing 4-meter surface). In this case the survey resulted in more than enough along-track density to compute favorable 1-meter surface density statistics even within the Set Line Spacing region which requires a relatively coarse cell size/density in comparison. 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: H13041_MB_1m_MLLW = 98.79%. 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 H3041. 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\Backscatter” 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.H13041_MB_1m_MLLW_FinalCARIS Raster Surface (CUBE)12.247.70NOAA_1mComplete Coverage (Option B) and super-density Set Line Spacing CoverageH13041_SSS_1m_100SSS Mosaic1N/A100% SSSH13041_SSS_1m_200SSS Mosaic1N/A200% SSSAs mentioned above, what was assigned as a survey comprising both Complete Coverage and Set Line Spacing coverage types (and surface delivery resolutions) is being delivered as a 1-meter, single resolution surface that covers the entire survey area. As such, one (1) MBES CUBE (Combined Uncertainty and Bathymetric Estimator) surface was delivered along with Survey H13041; "H13041_MB_1m_MLLW_Final." 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.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 115, 154, 189, 191, and 193 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, H13041_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 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 on 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.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 seafloor soundings for charted regions was at the northern end of H13041 (as presently charted). 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 H13041 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 H13041 surveyed soundings is shown in Figure 18. The figure displays a difference surface made by subtracting a 10-meter resolution depth surface generated from the H13041 MBES data from a 250-meter resolution depth surface interpolated from the charted ENC soundings within the project area. Regions of shoaling are represented by positive depth differences (hot colors) and regions of deepening are represented by negative depth differences (cool colors). In general the survey area has seen a general shoaling in the northern and eastern regions and a general deepening in the middle and southwestern regions. Areas of nominal change are also widespread. 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 H13041 surveyed soundings.file:H13041_Figure_18_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 noted above a general shoaling trend (on the order of 1-meter) occurs in the northern and eastern regions of the survey. Deepening on the order 1-meter is observed in the middle and southwestern regions of the survey. As anticipated, the surveyed 12-foot contour will shift south substantially from its presently charted position. This move was anticipated in light of the relatively recent soundings and contour placement associated with Survey H11670 (2007-2008). Presently, the west end of the charted 12-foot contour (within H13041) is offset a distance of approximately 2,400 meters between its representation within Survey H13041 and its representation within Survey H11670. This move affects both ENC US4LA15M and RNC 11349. The 18-foot contour enters H13041 in two locations. The first representation is a sinuous contour running essentially east-west at approximate latitude 29-20-00N. The second representation (contiguous with the first) enters the survey area's southwest corner. The 18-foot contour that enters the southwestern corner of the survey area is no longer valid based on recently surveyed deeper soundings and should be redrawn outside the bounds of the survey. The sinuous east-west contour moves south on its east end and movers slightly north on its west end. A 12-foot depth area located at approximate position 29-21-08.00N, 91-57-02.00W was disproved. The depths in this area are now deeper than 13 feet. A 12-foot depth area located at approximate position 29-21-31.00N, 91-57-57.00W was disproved. The depths in this area are now deeper than 12 feet. A 12-foot depth area located at approximate position 29-20-56.00N, 91-55-47.00W was disproved. The depths in this area are now deeper than 13 feet.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 18-foot (3-fathom) contour enters H13041 in two locations. The first representation is a nearly straight contour running essentially east-west at approximate latitude 29-20-00N. The second representation (contiguous with the first) enters the survey area's southwest corner. The 18-foot contour that enters the southwestern corner of the survey area is no longer valid based on recently surveyed deeper soundings and should be redrawn outside the bounds of the survey. The east-west contour moves south on its east end and moves slightly north on its west end. The northern edge of an 18-foot (3-fathom) depth area located at approximate position 29-17-46.00N, 91-57-56.00W was disproved. The depths in the area surveyed are now deeper than 18 feet.An overview of ENC US3GC03M (shaded orange) superimposed on RNC 11340. file:H13041_Figure_19_ENC_US3GC03M-on-RNC11340.jpgUS4LA21M80000302017-08-252017-10-18falseData from Survey H13041 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 H13041, eighty five (85) features were assigned for investigation within the Composite Source File (CSF): one (1) Wreck (WRECKS), eighteen (18) Platforms (OSFPLF), twenty seven (27) pipeline sections (PIPSOL), one (1) Pile (PILPNT), one (1) Light (LIGHTS), one (1) Mooring/Warping Facility (MORFAC) and thirty six (36) obstructions (OBSTRN). Of the assigned obstructions, all but two are "BSSE Wellheads." The Pile and one of the non-BSSE Wellhead obstructions (having area, not point, geometry) are co-located. The Light and Mooring/Warping facility are co-located. The assigned "Wreck PA," was disproved with 200% SSS and partial MBES coverage within a 160 meters search radius. The ENC US4LA15M wreck symbol correlates well with its RNC counterpart (about 10 meters apart). The ENC US3GC03M wreck symbol is approximately 76 meters from its ENC US4LA21M counterpart. The co-located Pile and Obstruction (area) are represented as a "Pipe PA" on RNC 11349. Both of these chart elements, located at position 29-21-41.96N, 91-56-55.85W were disproved with 200% SSS and partial MBES coverage within a 160 meters search radius. The ENC US4LA15M obstruction symbols correlate well their RNC counterparts (less than 10 meters apart). The "Pile PA" is not represented on ENC US3GC03M. The co-located Light and Mooring/Warping Facility located at position 29-23-02.36N, 91-57-27.29W are represented only by a light symbol (adjoining a platform symbol) on RNC 11349. The RNC (and ENC) show the light character as "8 Q 9ft Priv". Neither the light nor the mooring/warping facility (nor the adjacent platform) were found to exist and all were disproved with 200% SSS and partial MBES coverage within an 80 meter search radius. The ENC US4LA15M Light symbol and MORFAC dot-symbol correlate well with their RNC counterparts (about 10 meters apart). Neither the Light nor the MORFAC are represented on ENC US3GC03M. The missing light is the subject of H13041 DTON #1. The remaining non-BSSE Wellhead obstruction, a nonspecific "Obstruction PA," located at position 29-19-11.70N, 91-59-49.90W, was disproved with 200% SSS and partial MBES coverage within a 160 meters search radius. The ENC US4LA15M and ENC US3LA03M obstruction symbol, correlate well with the RNC counterpart. See DR Section D.2.6 Platforms for information regarding the verification or disproval of the charted platforms. Of the thirty four (34) assigned BSSE Wellhead obstructions, all are recommended for deletion. In many cases assigned BSSE wellheads 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 CSF-assigned BSSE Wellhead obstructions were either stand-alone features or were coincident with disproved CSF-assigned platforms. All disproved BSSE Wellhead obstructions were disproved with 200% SSS and partial MBES or Complete Coverage MBES in a 50-meter search radius (unless a larger radius was compulsory due to the missing platform). For a more complete description of the well head investigations, refer to the H13041 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. Twenty seven (27) pipeline features were assigned for investigation in the CSF. A number of the pipelines, as packaged and assigned in the CSF, extend outside the bounds of the H13041 survey area. As such, a number of the assigned pipelines are coincident with pipelines in adjacent sheets. During preliminary data processing there were forty one (41) pipeline or potential pipeline detections identified in Survey H13041. 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 eleven (11). All pipeline detections are less 1.0 meter above the seafloor. As such, no exposed pipelines were cause for DTON notification. 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. No "seeps" were detected in Survey H13041. 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 H13041 and only one (1) is a navigationally significant submerged feature worthy of description herein. 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 close proximity to one of the "missing" CSF platforms with position 29-20-08.33N, 92-00-35.24W an obstruction was surveyed at position 29-20-07.89N, 92-00-34.90W (Figure 20). This nominally 1.5-meter tall feature may otherwise have been cause for DTON notification except for the following: the relative depth of the obstruction as compared to nearby soundings, the obstruction's position coincides with a presently charted RNC platform symbol and, the obstruction is within 260 meters of a large, sprawling platform. It is recommended that the charted/CSF platform is removed from the chart and that an obstruction symbol is added at the aforementioned location. One of the surveyed platforms at CSF position 29-23-37.98N, 91-59-34.43W is surrounded by numerous pilings essentially making the footprint of the platform much larger than the actual platform itself. The pilings surrounding the platform, which can be described as a "satellite" platform or drying wellhead, are uncharted features and thus included in the FFF as piling features (PILPNT). Figure 21 depicts the "platform" and surrounding pilings.An obstruction was surveyed near the location of a disproved platform with CSF-defined position 29-20-08.33N, 92-00-35.24W.file:H13041_Figure_20_Obs%20near%20disproved%20platform.jpgA "satellite" platform is surrounded by numerous pilings. The pilings are new features and are included in the FFF.file:H13041_Figure_21_Platform%20with%20Pilings.jpgThe methods employed in conducting the Shoal and Hazard Features analysis are the same as described above for the Chart Comparison discussion. As mentioned above, there is a general shoaling trend across the extents of Survey H13041. However, there are numerous isolated deepening trends as well. There are a few locations that have seen up to 4.5 feet (1.4 meters) of shoaling and there are areas that have seen deepening on the order of 5.5 feet (1.7 meters). In light of the nearby charted soundings and the observed (and anticipated) vessel traffic the shoaling trend is not cause for undue concern nor is the 1.3 meter shoaling example cause for DTON notification. In general it can be stated that no new dangerous shoals were surveyed. Rather, a complete rework of the charted soundings and contours on the affected ENC/RNC products is required. 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 H13041 is generally soft mud.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 (1) ATON was assigned with Survey H13041. The CSF-"assigned" and ENC-charted Light (LIGHTS) are attributed with the same position: 29-23-02.361N, 91-57-27.285W. The Light List-published position of this light is 29-23-01.80N, 91-57-26.90W.  This light is depicted on ENC US4LA15M and RNC 11349. The CSF and the ENC also list a Mooring/warping facility (MORFAC) at the exact aforementioned position. The structure on which the light was presumably installed and the nearby adjacent platform 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 centered on the CSF provided ATON position. According to the Light List the light was on a pile. No evidence of a seafloor obstruction was detected within or in the vicinity of the 80-meter search radius. The missing ATON is the subject of H13041 DTON #1. As indicated above the light is listed in the Light List. No indication of the removal of the platform or the removal of the light are found in the LNM or NM consulted in reviewing this survey. According to information at the web address https://ocsdata.ncd.noaa.gov/ntm/resultList.aspx?Chart=11349&Edition=43&DateSince=20070516, the light was added to RNC 11349 with LNM 06/08 and has never been removed.No overhead features exist for this survey.As discussed above, twenty seven (27) assigned charted pipelines (PIPSOL) are located within Survey H13041. 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). 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. With one exception all CSF assigned pipelines are represented (within the survey area) on ENC US4LA15M as well as the the large scale RNC of the area, RNC 11349. The pipelines are not represented on ENC US3GC03M or RNC 11340. CSF vs. ENC vs. RNC pipeline inconsistencies are summarized below. At the following general location, a pipeline shown on ENC US4LA15M and RNC 11349 is not included in the CSF: 29-23-18.35N, 91-54-43.89W. 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 charted pipelines have a BOEM pipeline counterpart. However, the results of the analysis suggests that there are a few uncharted BOEM-listed pipe segments within Survey H13041. Figure 22 depicts uncharted BOEM pipelines. 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. Survey H13041 sheet limits are shown in black.file:H13041_Figure_22_BOEM%20Pipeline%20Analysis.jpgEighteen (18) platforms (OSFPLF) were assigned for investigation in the CSF for Survey H13041. Of the CSF platforms, fourteen (14) platforms were surveyed close to the CSF-defined position. All but one of the surveyed CSF platforms was greater than 10 meters from the CSF position. As such, all but one of the surveyed CSF platforms were marked for deletion and a new platform was added to the FFF in their place. It follows then the one of the surveyed CSF platforms is attributed "Retain" in the FFF. Four (4) CSF platforms were not found and 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. One of the "missing" platforms was recommended for deletion in the various Local Notice to Mariners and Notice to Mariners cited above. The NM recommendations follow: NM 41-17 11349 46Ed. 3/14 LAST NM 40/17 41/17 Delete Platform 29-20-49N 91-58-42W One platform which was recommended for deletion in both the LNM and NM (and was in fact non charted on the contemporary ENC/RNC) was found to exist at position 29-20-23.91N, 91-57-43.68W and was thus cause for DTON notification (H13041 DTON #2) . The LNM and NM notifications follow. NM 40-17 11349 46Ed. 3/14 LAST NM 37/17 40/17 Delete Platform 29-20-23N, 91-57-43W LNM 20/17 (May 17, 2017) Delete Platform 29-20-23.19N, 91-57-43.25W.  Images are included in the FFF for all verified platforms. The existing platforms are as follows (positions per CSF): 29-19-05.95N 91-59-09.28W 29-19-24.66N 92-00-33.67W 29-19-33.08N 91-59-30.12W 29-19-37.78N 91-58-59.40W 29-19-38.70N 91-59-26.77W 29-19-55.39N 91-59-12.07W 29-20-23.05N 91-57-43.03W 29-20-34.58N 91-56-55.09W 29-20-39.92N 91-59-49.48W 29-20-55.19N 91-59-19.20W 29-21-25.90N 91-59-34.68W 29-23-37.98N 91-59-34.43W 29-24-07.98N 91-59-22.14W 29-24-30.46N 91-59-32.32W 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. 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.aspxNo ferry routes or terminals exist for this survey.Abnormal seafloor and/or environmental conditions were not observed for this survey.Except 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. Marine 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 H13041 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