OPR-K354-KR-16Approaches to Atchafalaya BayGulf of MexicoOcean Surveys, Inc.H12907325 NM SSE of Marsh IslandLouisianaUnited States400002016George G. ReynoldsNavigable Area2016-07-262016-08-182016-09-30Multibeam 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 16 AUGUST 2016 TO 30 SEPTEMBER 2016 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 Atchafalaya Bay. The general locations of the survey limits are presented in Table 1.29.229741666791.856655555629.086138888991.6876111111Survey limits were acquired in accordance with the requirements in the Project Instructions and the HSSD.Per the hydrographic project instructions, the purpose of this project is to provide contemporary surveys to update National Ocean Service (NOS) nautical charting products. This project area is located within the vicinity of the Atchafalaya River Delta and the Port of Morgan City. The proposed project will cover both nearshore and offshore areas in the vicinity of the Atchafalaya River Basin and will update the nautical chart where depth contours have migrated. The project will cover approximately 130 square nautical miles of critical survey area in the Approaches to Atchafalaya Bay as designated in NOAA Hydrographic Survey Priorities, 2012 edition. Survey data from this project are intended to supersede all prior survey data in the common area.The entire survey is adequate to supersede previous data.All waters in survey areaComplete Coverage accomplished using either: A) Complete coverage MBES depth and backscatter data or B) 100% SSS coverage with concurrent set line spacing MBES depth and backscatter data.Survey Coverage is in accordance with the requirements in the Hydrographic Survey Project Instructions (July 26, 2016), the Statement of Work, [May 2016 (SOW)], and the Hydrographic Surveys Specifications and Deliverables, [March 2016 (HSSD)]. In all waters, Complete Coverage was accomplished by acquiring one hundred percent (100%) side scan sonar (SSS) coverage with concurrent multibeam echosounder (MBES) with backscatter. Data were acquired on a set line spacing plan. 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 35.92 square nautical miles (Figure 1). Survey H12907 MBES coverage overlaid on RNC 11340.H12907_Figure_1_Coverage.jpgR/V Ocean Explorer014.970135.310875.62096.490014.970135.310875.62096.49010.83400035.922016-08-182016-08-232016-08-312016-09-012016-09-022016-09-032016-09-042016-09-052016-09-102016-09-112016-09-212016-09-222016-09-232016-09-30The 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.Refer to the OPR-K354-KR-16 Data Acquisition and Processing Report (DAPR) for a complete description of data acquisition and processing systems, survey vessel, quality control procedures and data processing methods. Additional information to supplement sounding and survey data, and any deviations from the DAPR are discussed in the following sections.R/V Ocean Explorer182Survey operations were conducted from the R/V Ocean Explorer. The R/V Ocean Explorer, O.N. 905425, is an 18-meter aluminum vessel, with a 5.1-meter beam and nominally 2-meter draft, powered by two 1,000 HP Iveco diesel engines.Reson7125MBESEdgeTech4125SSSODIMMVP30 w/AML SVPTSound Speed SystemAMLMicro-XSound Speed SystemApplanixPOS MV 320 V.4Positioning and Attitude SystemTrimbleProBeaconPositioning SystemTrimbleSPS 461Positioning SystemTable 5 summarizes the primary equipment used to acquire MBES and SSS data. All equipment was installed, calibrated and operated in accordance with the DAPR.A total of 96.49 nm of cross line data were acquired August 18, 2016 (DN 231). Cross line mileage equaled 11.1% of the 875.62 nm of mainscheme MBES lines. Cross lines were run nominally perpendicular to mainscheme lines (Figure 2). Soundings from mainscheme lines and cross lines were compared periodically throughout survey operations reviewing preliminary MBES surfaces and using CARIS HIPS Subset Editor. Cross line 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 cross line data and the depth layer of a 1-meter CUBE surface composed only of mainscheme data. The cross line analysis results demonstrate excellent agreement between cross line soundings and mainscheme soundings, with the depth differences less than or equal to 0.30 meters with an average difference of 0.04 meters. The allowable TVU for the range of water depths within Survey H12907 is greater than 0.50 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 1,210,147. Of 1,210,147 possible comparison cells, 1,181,669 or 97.65% of the cells include cross line and mainscheme soundings that match within +/- 20 centimeters.An overview of the cross line layout on a 1-meter surface created from mainscheme MBES data and colored by depth. RNCs 11351 and 11349 are visible in the background.H12907_Figure_2_XLs.jpgThe graph shows a frequency distribution of the depth differences between the H12907 cross line data and the H12907 mainscheme MBES data. Statistics from the depth difference sample set are displayed above the graph.H12907_Figure_3_XL_Histogram.jpg0.030.09Discrete ZoningR/V Ocean Explorer11The 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 H12907 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 all finalized surfaces. 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." Finalized surfaces were used in this analysis. Surfaces were finalized using the “greater of the two” option as the basis for calculating “Final Uncertainty” in the CARIS “Finalize Base Surface” utility. Five (5) MBES CUBE (Combined Uncertainty and Bathymetric Estimator) surfaces were delivered along with Survey H12907 including "H12907_MB_1m_MLLW_Final" and four (4) 50-centimeter item investigation surfaces. The 1-meter surface is intended to satisfy coverage and sounding density requirements for Complete Coverage, Option B: 100% side scan sonar coverage with concurrent multibeam. The remaining 0.5-meter surfaces are intended to satisfy Object Detection Coverage and sounding density requirements over significant features. Results from the TVU QC indicate that 99.9997% of the nodes from all submitted surfaces meet IHO Order 1 uncertainty specifications, i.e. the ratio values of nearly all the nodes are less than -1. Of the 40,794,968 nodes considered, 105 had a ratio value below -1. Upon examination it was found that the nodes with ratio values below -1 were located over the various features covered by the investigation surfaces resulting in higher standard deviation values and finalized uncertainty values, which is to be expected over discrete features. Two (2) prior surveys and three (3) contemporary surveys junction with Survey H12907. Figure 4 displays the location of the prior and contemporary junction surveys for Project OPR-K354-KR-16.Survey junctions for Project OPR-K354-KR-16. RNC 11340 is displayed in the background.H12907_Figure_4_Junctions.jpgD00137400002005NOAA Time CharterNThe NOAA Time Charter's Survey D00137, a reconnaissance survey conducted in 2005, overlapped the northern border of H12907. Given that both Survey H12907 and Survey D00137 were acquired to meet Set Line Spacing with the MBES systems, the junction area between the two surveys was sparse. Depth data for Survey D00137 were downloaded from the National Geophysical Data Center (NGDC) website (http://www.ngdc.noaa.gov) in the form of a 5-meter resolution Bathymetric Attributed Grid (BAG), "D00137_5m_MLLW_1of1". To conduct the junction comparison a 5-meter CUBE surface was generated from the entire MBES data set for Survey H12907, "H12907_MB_5m_MLLW". In CARIS HIPS, depths from the "D00137_5m_MLLW_1of1" BAG were subtracted from the depths in the "H12907_MB_5m_MLLW" CUBE surface using the CARIS HIPS Difference Surface function. A histogram of the differences is shown in Figure 5. Depths from the H12907 survey show reasonable agreement with depths from the D00137 survey. Depth discrepancies equaled 37 centimeters or less with a mean difference of 19 centimeters. On average, Survey D00137 depths were shallower than H12907 depths. The largest discrepancy grouping between H12907 and D00137 survey depths (37 centimeters) and another discrepancy grouping of around 34 centimeters, occurred on only two of the seven instances where there was overlapping data. The reason for the relatively small bias is not clear. One possible reason for the bias is tide. The Descriptive Report for Survey D00137 is not available on the NGDC website. However, assuming that Survey D00137 was conducted around the same time as the other assigned junction surveys (H11288, H11290, H11415) it is noted that these surveys used a different tide source than the contemporary survey. The assigned junction surveys used either the Eugene Island, LA (876-4311) tide gauge or a gauge located in Galveston, TX (877-1510). Surface-to-surface difference histogram comparing Survey H12907 to D00137.H12907_Figure_5_D00137_Histogram.jpgH11290200002005NOAA Time CharterSENOAA Time Charter's Survey H11290, a hydrographic survey conducted in 2005, overlapped the far southeastern corner of H12907. Depth data for Survey H11290 were downloaded from the NGDC website in the form of a 1-meter resolution BAG, "H11290_1m_MLLW_2 of 4." Both MBES surfaces were acquired for 100 or 200% SSS coverage with Set Line Spacing; therefore, the horizontal overlap between the two surveys was sparse with an approximate overlap of 250 meters found in the small wedge shaped southeastern extent of Survey H12907. To conduct the junction comparison a 1-meter CUBE surface was generated from the MBES data set for Survey H12907, "H12907_MB_1m_MLLW." In CARIS HIPS, depths from the "H11290_1m_MLLW_2of4" BAG were subtracted from the depths in the "H12907_MB_1m_MLLW" CUBE surface using the CARIS HIPS Difference Surface function. A histogram of the differences is shown in Figure 6. Depths from the H12907 survey were deeper than depths from the H11290 survey, with a maximum depth discrepancy of 78 centimeters and an average difference of 54 centimeters. The mean and maximum vertical offset is relatively large. The reason for this bias could include the different tide sources employed in reducing the comparative datasets (see discussion for Junction D00137 above). Another potential cause of the discrepancy is depth changes due to sediment transport that occurred between survey times of acquisition. For example, in Survey H12906 (immediately east of Survey H12907) large bedforms (assumed to be mobile) are apparent. The bedforms are suggestive that this region could be prone to depth changes due to sediment transport. Furthermore, it is noted that Survey H11290 was completed on July 31, 2005. Less than a month later Hurricane Katrina made landfall in south Louisiana. Given the relatively shallow water depths in this area it is possible that this massive storm and subsequent storm events could be responsible for some depth change between surveys.Surface-to-surface difference histogram comparing Survey H12907to H11290.H12907_Figure_6_D11290_Histogram.jpgH12905400002016Ocean Surveys, Inc.NEThe approximate overlap between the bathymetric data from contemporary Surveys H12905 and H12907 was approximately 200 meters. Given that both surveys were acquired to meet 100% SSS Coverage, not complete MBES coverage, the junction area between the two surveys consists largely of the ends of three semi-coincidental, parallel track lines. Depths from 1-meter BASE surfaces compiled from the MBES data from each survey, "H12907_MB_1m_MLLW" and "H12905_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 H12907 survey show good agreement with the depths from the H12905 survey. Depth discrepancies generally equaled 20 centimeters or less with a mean difference of 14 centimeters.Surface-to-surface difference histogram comparing Survey H12907 to Survey H12905.H12907_Figure_7_H12905_Histogram.jpgH12906400002016Ocean Surveys, Inc.EThe overlap between the bathymetric data from contemporary Surveys H12907 and H12906 is approximately 400 meters. Given that both surveys were acquired to meet 100% SSS Coverage, not complete MBES coverage, the junction area between the two surveys occurs at trackline ends that are generally overlapping. Depths from 1-meter BASE surfaces compiled from the MBES data from each survey, "H12907_MB_1m_MLLW" and "H12906_MB_1m_MLLW," were compared using the CARIS HIPS Difference Surface function. A histogram of the differences is shown in Figure 8. Depths from the H12907 survey show good agreement with the depths from the H12906 survey. Depth discrepancies generally equaled 25 centimeters or less with a mean difference of 10 centimeters. The minor biases between surveyed depths appear to be tide related, as the agreement between survey depths from H12907 and H12906 vary with survey day. Where a difference between Survey depths is present, the offset is noted across the full swath of coincident lines from the same survey day, without any modification to system configuration, which is indicative of a tidal offset.Surface-to-surface difference histogram comparing Survey H12907 to H12906. H12907_Figure_8_H12906_Histogram.jpgH12908400002016Ocean Surveys, Inc.SThe overlap between the bathymetric data from contemporary Surveys H12907 and H12908 is approximately 270 meters. Both surveys were acquired to meet 100% SSS Coverage, not complete MBES coverage. The mainscheme line plans for H12907 and H12908 were oriented perpendicular to one another, a layout based on the charted depths and contours for the survey area indicating a very flat gradient in H12907 and a gradual deepening in H12908, with H12908 lines oriented parallel to the charted contour. The result generally is that the four northernmost NW-SE lines from Survey H12908 overlap the southern ends of the lines from Survey H12907. Depths from 1-meter BASE surfaces compiled from the MBES data from each survey, "H12907_MB_1m_MLLW" and "H12908_MB_1m_MLLW," were compared using the CARIS HIPS Difference Surface function. A histogram of the differences is shown in Figure 9. Depths from the H12907 survey show good agreement with the depths from the H12908 survey. Depth discrepancies generally equaled 20 centimeters or less with a mean difference of 3 centimeters. The minor biases between surveyed depths appear to be tide related, as the agreement between survey depths from H12907 and H12908 vary with survey day. Where a difference between Survey depths is present, the offset is noted across the full swath of coincident lines from the same survey day, without any modification to system configuration, which is indicative of a tidal offset.Surface-to-surface difference histogram comparing Survey H12907 to H12908. H12907_Figure_9_H12908_Histogram.jpgSonar system quality control checks were conducted as detailed in the Quality Control section of the DAPR. Results from the weekly MBES bar checks are included in Appendix II of the DAPR.MBES Time Sync Errors and GapsOccasional time sync alarms were observed during acquisition on the Reson 7125 Seabat display. 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. A few small along track data gaps associated with the Reson time sync error were noted in CARIS HIPS Subset Editor during processing of the MBES data wherein there is a short break in recorded profiles (Figure 10). Larger gaps were "filled" with additional MBES coverage. Remaining gaps do not exceed 3x3 nodes in the 1-meter Complete Coverage surface. Example of a small gap in MBES data associated with the Reson time sync error as it appears in CARIS Subset Editor (top left and bottom) and the same gap as it appears in a 1-meter CUBE surface (top right).H12907_Figure_10_Time-Sync.jpgTide OffsetReview of surface data indicates that there were a number of minor tide-related offsets between MBES data collected on different days scattered throughout Survey H12907. There were no noteworthy tide events that affected this survey. However, for the period of the survey, a nearly consistent offset with a magnitude averaging about 17 centimeters was apparent between the predicted and verified tides at the LAWMA, Amerada Pass LA tide station. Overall, the tide correctors were modeled well for Survey H12907, 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 11 highlights a portion of the survey area where the tidal offset varied with survey day. In Figure 11 a standard deviation surface depicts cross lines (oriented NW-SE) along with a number of mainscheme lines and tightly spaced investigation lines. The standard deviation surface and the subset cross section show a minor tide offset (< 0.2 m) which was prevalent between the cross line and the mainscheme/investigation lines. In two cases where investigation lines overlapped coincidental mainscheme lines the standard deviation surface appears bright green due to the opposing tide offset in the various lines contributing to the stacked coverage (blue over yellow over purple in the cross section display). Investigation lines run on DN 254 (purple) coincided with mainscheme lines run early on day DN 255 (blue) soon after passage of a squall. It is surmised that the squall, having a different wind direction and magnitude than before/after squall weather pattern, contributed to the tide offset highlighted in Figure 11.The top image shows a portion of the Standard Deviation layer from the H12907 1-meter CUBE surface. In the Standard Deviation layer the cyan and green colors indicate areas of higher standard deviation in the surface due to minor tide offsets. The bottom image displays MBES data loaded into CARIS Subset Editor with a tide-related vertical offset noted between investigation soundings collected on DN 254 (purple), a cross line collected on DN 231 (yellow), and mainscheme soundings collected on DN 255 (blue) and DN 267 (orange). Depths and distances are in meters. H12907_Figure_11_Tide-Offset.jpgSSS 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, SSS lines with excessive refraction were rejected or the portion of the line with severe refraction was re-run.Refraction in the SSS imagery is visible in the outer range of both channels of a survey line acquired with the fixed-mount 4125 SSS.H12907_Figure_12_SSS_Refraction.jpgSea State Induced White Streaks in SSS Imagery and MBES "Blowouts"The Reson 7125 system experienced periodic bursts of motion-induced noise or “blowouts,” typically affecting between 1 and 4 sequential profiles. Efforts were made to reduce this noise during acquisition, including adjustments to system gain and power, in addition to the multibeam pole fairing that was installed to reduce cavitation effects. The noise bursts were infrequent and were encountered when sea state worsened. Accepted data effected 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 "white streaks" across the SSS record, which occasionally coincided with blowouts in the MBES data (Figure 13). 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.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 in the raw SSS imagery (bottom), which presented as white streaks across the processed SSS record (top left). In this instance, the SSS white streak coincided with an MBES blowout (top right and middle image).H12907_Figure_13_MB-SSS_Blowouts.jpgFish in SSS Imagery and MBES dataOccasional fish and marine sea life were seen in the SSS and MBES data, either as lone swimmers or in schools (Figures 14 - 15). 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 a presence within the survey area, as well as large schools of fish or shrimp, which at times created large shadows in the SSS imagery and gaps in the MBES data where acoustic returns on fish and dolphins were rejected from the data. To ensure that possible significant features were not located in the fish and dolphin shadows, fish/dolphin related coverage gaps were developed with 200% SSS coverage or object detection MBES coverage.A large school of fish as it appears in the MBES data and in the water column of the slant range corrected SSS imagery. The top image was taken in CARIS Subset Editor 3D with rejected soundings colored grey. The bottom image of the same fish school was taken in the CARIS SIPS waterfall display window.H12907_Figure_14_Fish.jpgFish or shrimp "balls" as they appeared in the slant range corrected SSS imagery (left) and in the MBES data (right). The dense fish or shrimp balls had dark returns in the SSS record and were often clustered close to the seafloor as noted in the MBES data in CARIS HIPS Subset Editor 3D, with the rejected fish soundings colored grey.H12907_Figure_15_Fish-Shrimp_Balls.jpgSound speed profile data were acquired with the ODIM MVP30 approximately every 15 minutes as documented in the DAPR. All MBES lines were sound speed corrected using CARIS HIPS' "Nearest in Distance Within Time" method with the time set to two (2) hours. Based on prior survey experience in the northern Gulf of Mexico, OSI expected to encounter high variability in the speed of sound with abrupt gradient changes linked to dynamic salinity and temperature conditions. Fortunately, with the exception of the last day of survey for Project OPR-K354-KR-16, the water column was relatively well-mixed, which reduced the incidence of refraction in the SSS and MBES data sets as compared to OSI's recent Gulf of Mexico experience. OSI submitted H12907 sound speed data in NetCDF format to the National Centers for Environmental Information (NCEI) on December 14, 2016 (DN 349) via the S2N tool. NCEI assigned the sound speed submission Accession Number 0157605. 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 to a depth of 20 meters, i.e. Complete Coverage, Option B as defined in Section 5.2.2.3 of the HSSD 2016. All depths within Survey H12907 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 SSS coverage. All potentially significant features located with mainscheme SSS or MBES were developed with high density multibeam sonar data to meet the HSSD requirement of Object Detection coverage. 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 for each finalized BASE surface. The HSSD states that at least 80% of the surface nodes shall be populated with at least 5 soundings for the Complete Coverage (Option B) 1-meter surface, and that at least 95% of the nodes shall be populated with at least 5 soundings for the 50 cm Object Detection surfaces. For the purpose of obtaining the most accurate surface density statistics, the unfinalized surfaces were used for the Density QC check as it was discovered that during surface finalization a density value of one (1) was assigned to all nodes containing a designated sounding, regardless of the node's sounding density value pre-finalization. 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 ≥ 5 for every submitted CUBE surface. The percentage of nodes with density greater than or equal to 5 soundings for the 1-meter Complete Coverage surface was as follows: H12907_MB_1m_MLLW = 99.44%. All four (4) of the Object Detection surfaces had 100% of the nodes populated with a density far in excess of 5 soundings. 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 H12907. Backscatter data were recorded with HYSWEEP SURVEY in .7K format. 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 “Backscatter” directory per the HSSD, Section 8.3.4 Backscatter Deliverables.CARISHIPS/SIPS7.1.2CARISHIPS/SIPS7.1.2NOAA Profile V_5_4.Software versions described in Section A of the DAPR were used throughout acquisition and processing of data for Project OPR-K354-KR-16.H12907_MB_1m_MLLW_FinalCUBE14.068NOAA_1mComplete Coverage (Option B)H12907_MB_50cm_MLLW_7-082_FinalCUBE0.55.957.26NOAA_0.5mObject DetectionH12907_MB_50cm_MLLW_7-083_FinalCUBE0.54.066.58NOAA_0.5mObject DetectionH12907_MB_50cm_MLLW_7-093_FinalCUBE0.56.367.99NOAA_0.5mObject DetectionH12907_MB_50cm_MLLW_7-097_FinalCUBE0.55.717.55NOAA_0.5mObject DetectionH12907_SSS_1m_100SSS Mosaic GeoTiff1N/A100% SSSH12907_SSS_1m_200SSS Mosaic GeoTiff1N/A200% SSSFive (5) MBES CUBE surfaces and two (2) SSS mosaics comprise the total surfaces delivered with Survey H12907. To demonstrate MBES coverage requirements were met for Complete Coverage (Option B), a 1-meter CUBE surface was generated for the entire survey area. Four (4) small field sheets were generated over significant features and populated with 50-centimeter CUBE surfaces to demonstrate Object Detection coverage. 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-16.Mean Lower Low WaterLAWMA, Amerada Pass, LA 876-4227Eugene Island, LA 876-4314Offshore Bottom Mounted Pressure Gauge N/ADiscrete Zoning8764227.tidVerified ObservedK354KR2016 Revised Zoning 20161103.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. The Eugene Island gauge data were used only for tide zone refinement analysis not for reducing soundings to MLLW. Discrete zoning methods were utilized to apply tide correctors in CARIS HIPS. The survey area is located within Zones WGM283, WGM282, and WGM281 as provided in the preliminary tidal zoning scheme included with the project SOW. Pursuant to the "strong recommendation" in the Tides and Water Levels Statement of Work provided with the Project Instructions, two Bottom Mounted Pressure Gauges (BMPGs) were installed in the southwestern end of the project area in order to better understand the tidal propagation and zoning error for the discrete zones. The BMPG water level data were not used for tide correction of soundings; the gauges served as a "zoning station" acquiring data used to update the tidal range and phase correctors and to derive a tide zoning error estimate for the project area. Two BMPGs, one primary gauge and a back-up, were deployed for over 30 days from August 17 (DN 230) to September 24 (DN 268), logging data continuously for the entire deployment. OSI's subcontractor, JOA Surveys, processed the downloaded pressure data to calculate water levels and to compute the tidal datum for the BMPG zoning station. Water levels from the BMPG station were used along with data from the LAWMA and Eugene Island NWLON stations to refine the phase and range correctors provided in CO-OPS preliminary zoning scheme. The final zoning scheme, K354KR2016 Revised Zoning 20161103.zdf, includes new time and range correctors for each preliminary zone, but the preliminary zone geometry was retained along with the CO-OPS provided names. Based on the results of cross line analysis, the time and range factors as provided in the final zoning scheme are adequate. Please refer to JOA's OPR-K354-KR2016 Zoning Report.pdf included with the Tide deliverables. Tide station deliverables required in Section 4.7.5 of the HSSD were submitted to CO-OPS on November 9, 2016, as documented in an email included with Correspondence in Appendix II, OPR-K354-KR-16_BMPG_Transmittal.pdf. As of this time, OSI has not received and does not anticipate receiving a station name or ID number for the BMPG Gauges.North American Datum of 1983 (NAD83)UTM Zone 15 NorthEnglish Turn, LA, 293 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, H12907.FFF.000, is referenced to the World Geodetic System Datum of 1984 (WGS 84) as specified in HTD 2016-03, which revised the HSSD 2016 Section 2.1 Horizontal Datum such that all positions will be referenced to NAD 83 and "the only exception for the NAD 83 datum requirement is that the S-57 feature file will be in the WGS 84 datum". All MBES and SSS line and item investigation position data were acquired using an Applanix POS-MV operating in Differential GPS (DGPS) mode. The unit was configured to receive USCG Differential beacon correctors from the English Turn, LA station. A secondary GPS, used to facilitate real-time horizontal control confidence checks, was supplied with correctors from the Marinestar subscription service. Prior to and during the course of the survey the accuracy of the primary positioning system was verified by means of a physical measurement to a horizontal control point established at the vessel’s base of operation, a dock at the Port of Morgan City. Position confidence checks were accomplished, when possible, during fuel or weather stops. Refer to the DAPR and HVCR for additional details. Horizontal Offset in DGPS PositioningA horizontal offset of less than 1 meter was noted between the MBES survey lines collected over significant features developed to meet object detection coverage (Figure 16). The shift in horizontal position between lines can be attributed to the use of DGPS correctors for positioning with the survey area located over 150 kilometers from the English Turn station. The horizontal positional shift was well within the limits of horizontal accuracy as defined in Section 3.1.1 Horizontal Position Uncertainty of the HSSD 2016.Example of a feature developed with object detection MBES coverage that exhibited a horizontal positioning shift between survey lines. The image shows an unknown obstruction with soundings colored by line in CARIS Subset Editor 2D Window.H12907_Figure_16_DGPS_Offset.jpgChart comparisons were performed in CARIS HIPS/SIPS and Notebook using finalized BASE surfaces and contours and selected soundings. The latest editions of the NOAA NOS Raster Nautical Charts (RNC) and 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 RNCs and ENCs used for final comparisons were downloaded on December 19, 2016 and are submitted with the survey deliverables. Local Notice to Mariners (LNM) and Notice to Mariners (NM) spanning the period beginning at the date of issuance of the preliminary Hydrographic Project Instructions (June 28, 2016) and ending on December 14, 2016 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 least depth soundings for charted regions were on obstruction features; however, 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 H12907 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 H12907 surveyed soundings is shown in Figure 17. The figure displays a difference surface made by subtracting a 10-meter resolution depth surface generated from the H12907 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 and regions of deepening are represented by negative depth differences. This analysis indicates a general deepening trend across the survey area (green/blue shading) with isolated regions having essentially no change (grey shading) . A detailed description of each chart comparison follows.A depth difference surface overlaid on RNCs 11351 and 11349 provides an overview of the areas of change between charted depths and H12907 surveyed soundings.H12907_Figure_17_Chart_Comp_Overview.jpg113496480000462014-032016-11-152016-10-29The west side of Survey H12907 intersects with a small portion of RNC 11349. The soundings from survey H12907 agreed well with the charted depths, with soundings differing from charted depths by approximately 0 to 2 feet (0.6 meters). No charted contours coincide with the H12907 survey area.113516380000432012-032016-11-292016-10-29There is good agreement between the H12907 surveyed soundings and the RNC 11351 charted depths, with soundings differing from the charted depths by approximately 0 to 3 feet (0.9 meters). Surveyed depths overall were slightly deeper than charted depths with all charted 18-foot contours being disproved; the surveyed soundings over the charted 18-foot contours ranged between 19 to 21 feet. With the exception of a new obstruction having a least depth of 13 feet (4.06 m, +/- 0.23 TPU) (reported as a DtoN), the existence of the charted 18-foot contour, as drawn within the H12907 survey area, is not supported by the MBES data (Figure 18). In fact, the majority of surveyed soundings are deeper than 19 feet.Soundings less than or equal to 18 feet within Survey H12907 (aside from new features) are highlighted in blue and shown in comparison to the charted 18-foot contour on RNC 11351. All depths are in feet.H12907_Figure_18_RNC11351_18ft_ctr.jpg1134049458596792016-022016-11-292016-10-29Other than least depths on obstructions, no soundings from RNC 11340 exist within the H12907 survey area. The 3-fathom contour intersects the northwest and southeast portions of H12907. The location of the 3-fathom contour was disproved by the surveyed soundings, with surveyed depths being 0.2 to 0.5 fathoms (1.2 to 3 feet) deeper than the charted 3-fathom contour. US4LA15M80000232014-11-062016-10-24falseRNC 11349 is the source for ENC US4LA15M; therefore, the positions and values of the soundings and contours included in ENC US4LA15M are identical to those charted on RNC 11349. All chart comparison notes entered under the RNC 11349 apply to US5LA15M.US4LA21M80000272015-03-252016-12-08falseRNC 11351 is the source for ENC US4LA21M; therefore, the positions and values of the soundings and contours included in ENC US4LA21M are identical to those charted on RNC 11351. All chart comparison notes entered under the RNC 11351 apply to US5LA21M.US3GC03M459596472015-02-202016-12-12falseRNC 11340 is the source for ENC US3GC03M; therefore, the positions and values of the soundings and contours included in ENC US3GC03M are identical to those charted on RNC 11340. All chart comparison notes entered under the RNC 11340 apply to US3GC03M.No Maritime Boundary Points were assigned for this survey.The following features were assigned for investigation within the Composite Source File (CSF) provided with the OPR-K354-KR-16 Project Instructions: Eight (8) charted platforms (OFSPLF) of which one is described as submerged and charted as "Platform PA (ruins)". - 21 BSSE well head obstructions (OBSTRN) - Two (2) Obstruction PA (OBSTRN) - One (1) wreck (WRECKS) Of the assigned platforms only three of the eight were found to exist. The remaining assigned platforms, including the submerged platform, were disproved visually and with 200% SSS coverage and partial MBES coverage within a search area centered on the CSF provided position and defined by a 50-meter or 80-meter (PA feature) radius. Platforms are discussed further in Section D.2. The BSSE well head obstructions were not charted but were submitted to be verified or disproved by OSI. Investigation requirements for the BSSE well heads were provided to OSI in an email dated April 22, 2016 which is submitted with the Correspondence in the DR Appendix II. The well head investigation requirements were as follows: - If obstruction is found and considered a danger to navigation, develop the feature (7.3.3), designate the feature (7.4), submit it as a DtoN (1.5), and include it in the FFF (7.3). - If obstruction is found and merits individual cartographic representation, develop the feature (7.3.3), designate it (7.4), and submit in FFF (7.3). - If obstruction is found and does not merit cartographic representation, do not investigate it as a feature. Include it in the FFF with “descrp = delete” and “remrks=obstruction addressed as represented in the surface” - If the obstruction is not found, in cases where 100% SSS with concurrent multibeam is being used as the primary coverage technique, a 50m disproval search radius using a technique described in Section 7.3.4 is necessary. Of the assigned BSSE well head features. it is recommended that all 21 BSSE well heads remain uncharted. Multiple BSSE well heads were correlated either with another BSSE well head assignment (one case) or with a charted platform. All but one BSSE well head was disproved with 200% SSS and partial MBES. For one BSSE well head located at 29-09-41.47 N, 91-49-31.47 W, a small sliver of bottom within the 50-meter search radius was not ensonified with the 200% SSS coverage but the 100% coverage clearly depicted a seafloor devoid of features. See the FFF for additional information regarding the investigated BSSE well head obstructions. The source date (SORDAT) and source indication (SORIND) attribute fields were blank for the BSSE well head features submitted in the CSF; therefore, the SORDAT and SORIND fields are blank for the disproved well heads attributed with a description (descrp) of "Delete" in the FFF. A charted Obstn PA located at 29-09-47.11 N, 91-49-31.54 W, "a 15ft by 10ft diameter tank" per the AWOIS database description, was disproved with 200% SSS and partial MBES coverage within a search area defined by an 80 m radius. A new tank like obstruction that is included in the FFF was developed with object detection MBES coverage approximately 2.5 kilometers SW of the Obstn PA, possibly the actual position of the Obstn PA (see DR Section D.1.5 Uncharted Features). An Obstn PA located at 29-12-00.81 N, 91-47-18.43 W, "a submerged obstruction" that "snagged an unknown amount of cable" per the AWOIS database description, was disproved with 200% SSS and partial MBES coverage within a search area defined by an 80 m radius. A new obstruction, most likely the actual position of the charted Obstn PA, was developed approximately 1.3 kilometers NNW of the charted Obstn PA and submitted as a Danger to Navigation (see DR Section D.1.6 Dangers to Navigation). The charted Wreck PA at the CSF defined location of 29-10-00.81 N, 91-45-00.43 W was disproved at it's charted location with 200% SSS and partial MBES coverage within a search area defined by an 80 m radius. A new 60-foot wreck was developed with object detection MBES coverage approximately 380 meters NNW of the charted wreck position and was submitted as a Danger to Navigation (see DR Section D.1.6 Dangers to Navigation). As of December 19, 2016, the date the RNCs and ENCs were downloaded for chart comparison, the original Wreck PA had been deleted from the chart and replaced with the new H12907 position (Figure 19). The Platform PA (ruins) feature charted on RNC 11351 and ENC US4LA21M at 29-05-37.81 N, 91-45-47.80 W was charted as an Obstn PA on RNC 11340 and ENC US3GC03M. The Platform PA (ruins) as charted on RNC 11351/ENC US4LA21M was submitted for investigation in the CSF. The platform ruins were disproved with 200% SSS and partial MBES at its charted location within the search area defined by an 80 meter radius. A new obstruction, most likely the actual position of the platform ruins, was developed approximately 125 meters east of the charted Platform PA (ruins)/Obstn PA and is included in the H12907 FFF (see DR Section D.1.5 Uncharted Features).The left image is the Wreck PA as charted on RNC 11351 on August 26, 2016 and the right image is the H12907 surveyed position and depth of the wreck as charted on RNC 11351 December 19, 2016.H12907_Figure_19_Wk_PA.jpg A large tank like feature with a least depth of 19 feet (5.95 m, ±0.23 TPU) was developed with object detection MBES coverage at position 29-08-43.78 N, 91-50-28.88 W, most likely the actual position of the "15ft by 10ft diameter tank" charted Obstn PA discussed above. The feature appears to be embedded in the seafloor and protrudes less than 1 meter above the seafloor (Figure 20). Two significant features were positioned within the footprint of a disproved charted platform at position 29-05-38.32 N, 091-45-43.21 W. Two pipe like obstructions over 1 meter tall and one with an insignificant height of 0.65 meters tall were developed with object detection MBES coverage with a least depth of 18 feet (5.71 m, ±0.23 TPU) and were possible evidence of a ruined or removed platform (Figure 21).A 19-foot, tank like obstruction is represented in CARIS HIPS Subset Editor 3D and 2D views with the soundings colored by depth and depths and units in meters.H12907_Figure_20_Tank_Obstn.jpgSeveral pipe like features were developed in the vicinity of a disproved charted platform as shown in the left image with a 1-meter CUBE surface overlaid on RNC 11351. On the right, the obstructions are shown in Subset Editor 2D view with depths and units in meters.H12907_Figure_21_Pipe_Obstns.jpg2H12907_DtoN_1_Wk.0002016-10-04H12907_DtoN_1_Obstn.0002016-10-04Two (2) Danger to Navigation (DtoN) S-57 files (.000) were submitted to the Atlantic Hydrographic Branch (AHB) for Survey H12907. The DtoN #1 submission describes a wreck approximately 380 meters NNW of a charted wreck PA which was disproved. The new wreck's surveyed position is 29-10-12.05 N, 91-45-06.83 W. The wreck DtoN was submitted by AHB to the Nautical Data Branch (NDB) and Marine Chart Division (MCD) on October 5, 2016 and has since been updated on RNCs 11351 and 11340 and ENCs US4LA21M and US3GC03M. The Local Notice to Mariners (LNM) Edition 44 for District 8 (44/16) included chart updates for RNC 11351 and 11340 to add the new wreck at the following position: 29-10-12.10 N, 91-45-06.80 W. The DtoN #2 submission describes an obstruction located approximately 1.3 kilometers NW of a charted obstruction PA which was disproved. The position of the new obstruction is 29-12-44.22 N, 91-47-32.44 W. The obstruction DtoN was submitted by AHB to the Nautical Data Branch (NDB) and Marine Chart Division (MCD) on October 5, 2016 and has since been updated on RNCs 11351 and 11340 and ENCs US4LA21M and US3GC03M. The Local Notice to Mariners (LNM) Edition 44 for District 8 (44/16) included chart updates for RNC 11351 and 11340 to add the new obstruction at the following position: 29-12-44.20 N, 91-47-32.40 W. The DtoNs are included in the H12907 S-57 FFF, H12907.FFF.000. The value of sounding (VALSOU) depths for the obstruction and wreck submitted as DtoNs have been updated in the FFF following the application of final tides to the MBES data set. Danger to Navigation Reports as well as correspondence regarding the DtoN submissions are included in Appendix II of this report.A caution area (CTNARE) note encompasses the entirety of the intersection of the H12907 survey area and RNC 11340 and ENC US3GC03M stating the following: "Gas and Oil Well Structures. Platforms, gas and oil well structures, some of which are submerged and capped, and submarine pipelines and cables are charted." Similarly, a Caution Note for RNC 11351 and ENC US4LA21M stated: "Additional uncharted submarine pipelines and submarine cables may exist within the area of this chart. Not all submarine pipelines and sub-marine cables are required to be buried, and those that were originally buried may have become exposed. Mariners should use extreme caution when operating vessels in depths of water comparable to their draft in areas where pipelines and cables may exist, and when anchoring, dragging, or trawling. Covered wells may be marked by lighted or unlighted buoys." The caution note was included in the text files referenced in the Textual description (TXTDSC) fields of the PIPSOL (pipeline) and M_NPUB (nautical publication information) features. The Caution Notes are warranted given the abundance of charted platforms, pipelines and possible well heads within the project area. No exposed pipelines were located within H12907; however, many segments of exposed pipeline were developed within the contemporary survey areas of project OPR-K354-KR-16. A Tide Rips/Water Turbulence (WATTUR) feature was positioned at 29-09-47.82 N, 91-46-34.09 W on RNC 11351 and ENC US4LA21M and at 29-09-28.68 N, 91-45-43.71 W on RNC 11340 and ENC US3GC03M. While not specifically confirmed at the charted location, tide rips were documented by the field crew in the acquisition log and photographically within the project area (Figure 22).Photograph of tide rip taken in the southeast corner of Survey H12906 on September 29, 2016 (DN 272).H12907_Figure_22_Tide_Rip.jpgNo 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.Four (4) bottom samples were acquired to determine bottom characteristics. Bottom samples were assigned in the PRF provided with the Hydrographic Survey Project Instructions. There were no deviations from the assigned bottom sampling plan. A position and description of each sample are provided as attributed SBDARE objects in the FFF. Digital images with identification reference numbers are submitted with the survey data and referenced in the NOAA extended attributes ‘images’ field.No shoreline exists within this survey.Prior survey data exists for this survey area. However, with the exception of the assigned junction surveys, prior data were not investigated.No Aids to navigation (ATONs) exist for this survey.Overhead features do not exist for this survey.Compared to the contemporary surveys in Project OPR-K354-KR-16, relatively few charted pipelines are located within Survey H12907. Pipes colored magenta represent supply pipelines for oil, gas, chemicals, or water, according to Chart No. 1: Nautical Chart Symbols, Abbreviations and Terms downloaded from the Office of Coast Survey (OCS) website. None of the charted pipelines have a buried depth value (BURDEP); however, no unburied charted pipelines were visible in the SSS or MBES data. Review of information contained in a shape file (.SHP) downloaded from the Bureau of Ocean Energy Management (BOEM) on April 25, 2016 suggests that there may be two uncharted pipelines within Survey H12907. The BOEM pipeline shape file that intersects with the OPR-K354-KR-16 project area was reprojected to UTM Zone 15N, NAD83 and saved as a .DXF file and converted to a .HOB file. In CARIS Notebook, the BOEM pipeline HOB file was then visually compared to the charted pipelines within the project area to identify any potentially uncharted BOEM pipelines. While the majority of the pipelines in the BOEM file corresponded with charted pipelines, two BOEM reported pipelines were not charted. There was no visible evidence in the MBES or SSS data of the existence of the uncharted pipelines. An overview of the uncharted BOEM-defined pipelines that intersect Survey H112907 is provided in Figure 23. The shape file, “ppl_arcs.shp” and re-projected .DXF file, “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: http://www.data.boem.gov/homepg/data_center/mapping/geographic_mapping.asp.Two reported BOEM-defined pipelines that are not charted are highlighted in pink in reference to RNCs 11351 and 11349 with the H12907 survey outline shown in orange.H12907_Figure_23_BOEM_Pipes.jpgNo ferry routes or terminals exist for this survey.Eight (8) "assigned" platforms were included for investigation in the CSF. Of the eight assigned platforms, five were disproved with 200% SSS and partial MBES coverage within a search area defined by a 50-meter radius centered on the CSF position. The remaining three platforms were positioned close enough to the CSF-provided positions to be attributed with the "retain" value, i.e. the surveyed platform positions were within 2 mm at the survey scale (80 m at 1:40000) to the charted platform positions. The remaining platforms in Survey H12907 are located at the following locations: 29-05-33.61 N, 91-45-39.85 W; 29-05-22.00 N, 91-45-36.99 W; and 29-09-03.80 N, 91-45-34.59 W. See the FFF for additional information including images.Many small circular depressions were visible in the MBES data throughout the survey area and were clustered in the scour area around obstructions, wrecks and platforms (Figure 24). The holes are randomly spaced, less than 50 centimeters deep, and do not appear to be associated with industrial activity. They are more likely related to a natural phenomenon, possibly ground fish-created habitat, as some species in the Gulf of Mexico (i.e. red grouper) are known to excavate depressions in flat, sandy bottoms (See Wall, Carrie C., et al. "Spatial and temporal variability of red grouper holes within Steamboat Lumps Marine Reserve, Gulf of Mexico." Marine Ecology Progress Series (Impact Factor: 2.62). 2011. 431:243-254.)Possible ground fish habitat holes as they appeared in the MBES data displayed in CARIS Subset Editor 2D and 3D windows with the soundings colored by depth.H12907_Figure_24_Fish_Holes.jpgNo construction or dredging existed within the survey limits at the time of data acquisition.Marine Mammal ObservationsPer direction in Section 1.4 and 1.4.1 of the HSSD all survey and vessel operations personnel aboard the vessel used during Project OPR-K354-KR-16 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 K of the HSSD. As compared to past years survey work in the Gulf of Mexico, dolphin sightings during the contemporary survey were relatively sparse. This is attributed to the area of operation for the contemporary survey. During the course of Project OPR-K354-KR-16 only 13 individual visual dolphin sightings occurred. Digital versions (.PDF format) of completed 11US (POP) forms along with the Project's marine mammal training record were compiled and transmitted to the OCS Environmental Compliance Coordinator, Jay Nunenkamp, with a CC to the Project's COR, Paul Turner. These records are also included in Descriptive Report Appendix II. Coast Pilot ReviewA "Coast Pilot Field Report" as described in Section 8.1.3 in the HSSD was not provided by HSD Operations. Per a June 2 email from the COR: "There are no specific items to investigate with regards to the Coast Pilot". OSI conducted a general review of relevant Coast Pilot excerpts. Specifically, pertinent paragraphs from the following Coast Pilot section were considered: Coast Pilot 5 - 44th Edition, 2016 updated through 13-November-2016, Mississippi River to Sabine Pass. Within the Coast Pilot Edition mentioned above there are no specific, detailed, relevant entries concerning the assigned 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” (as mentioned in the HSSD Section 8.1.3), there are only a few Coast Pilot paragraph descriptions that OSI's general review attempts to address. OSI's Coast Pilot Review is included in Descriptive Report Appendix II. Correspondence between OSI and the Project COR confirming OSI's understanding of the Coast Pilot reporting requirement is included in the Correspondence directory of the Descriptive Report Appendix II.No new surveys or further investigations are recommended for this area.No new insets are recommended for this area.As Chief of Party, field operations for this hydrographic survey were conducted under my direct supervision, with frequent personal checks of progress and adequacy. I have reviewed the attached survey data and reports.All field sheets, this Descriptive Report, and all accompanying records and data are approved. All records are forwarded for final review and processing to the Processing Branch.The survey data meets or exceeds requirements as set forth in the NOS Hydrographic Surveys and Specifications Deliverables Manual, 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 Party2017-01-23Data Acquisition and Processing Report2017-01-23Horizontal and Vertical Control Report2017-01-23