In accordance with HSSD Section 2.2, the horizontal datum for this project is NAD83. HSSD Section 2.2 states that the “only exception for the NAD83 datum requirement is that the S-57 Final Feature File (Section 7.3) will be in the WGS84 datum to comply with international S-57 specifications”. As discussed in the DAPR Section C.7, for every feature flag in a MBES GSF file, SABER converts the position from the NAD83 datum to the WGS84 datum to generate the S-57 file and comply with HSSD and IHO requirements. Feature positions meet the precision stated in HSSD Section 7.4 for each respective datum. Depending on geographic reference there may be approximately a 1-meter difference comparing positions between NAD83 and WGS84 datums. Therefore, if the feature overrides from the BAG surface (NAD83) are compared to the Final Feature File S-57 positions (WGS84) it is anticipated that there could be positional differences exceeding those listed in Section 7.4 of the HSSD. Additional information discussing the vertical and horizontal control for this survey can be found in the DAPR.Refer to the DAPR for details regarding the application of VDatum to the MBES data files. No final tide note was provided nor was it required from NOAA Center for Operational Oceanographic Products and Services (CO-OPS).OPR-K380-KR-21_NAD83_VDatum_MLLW.covERS via VDATUMMean Lower Low WaterProjected UTM 15North American Datum 1983The vessel kinematic data (POS/MV files) were post-processed in Applanix POSPac software using the Applanix PP-RTX solution to generate the Smoothed Best Estimate of Trajectory (SBET) solutions which were applied through SABER to the multibeam data. Refer to the DAPR for additional information and for details regarding all antenna and transducer offsets. Any soundings with total horizontal uncertainties exceeding the maximum allowable IHO S-44 6th Edition Order 1a specifications were flagged as invalid and therefore were not used in the CUBE depth calculations.Leidos chose to achieve the coverage requirement using Complete Coverage, Option B (100% side scan sonar coverage with concurrent multibeam). Survey coverage achieved was in accordance with the requirements in the Project Instructions and the HSSD (Figure 2 through Figure 4).Complete Coverage (Refer to HSSD Section 5.2.2.3)All waters in survey area Sheets 2 through 5This survey covers the general vicinity of the entrance channel to Port Freeport, Texas between the U.S. Coast Guard Station on the northwest of the entrance and Quintana Harbor to the southwest. The survey will wind 4.7 nautical miles south and west, around the Dow Chemical Plant Thumb to the Freeport Channel terminus. The surveyed area extends offshore 11 nautical miles to cover the approach channel, and 18 nautical miles southwest and 8 nautical miles northwest, outside safety fairway, where the AIS traffic deems intensity. Port Freeport, TX is undergoing channel expansion and deepening administered by the U.S Army Corps of Engineers. Freeport will become the deepest port in Texas once the entrance and terminal channels reach the authorized 51-56 feet depth. With the physical position on the Intercoastal Waterway, direct rail and highway connections to major Texas hubs, and the deepened channels, Port Freeport is poised to exceed its current 28th ranking as the U.S. busiest port in tonnage transfer. Several powerful storms impacted the Port Freeport since the offshore vicinity was last surveyed in 2002 and the nearshore vicinity was last surveyed in the 1930s and 1960s. The Office of Coast Survey expects that modern hydrographic techniques will find significant changes to the seabed due to hurricane forces transforming the seafloor. Survey data from this project is intended to supersede all prior survey data in the common area.000001401.7565.30004.66000001401.7565.3000M/V Atlantic Surveyor800056.332021-08-182021-08-232021-08-242021-08-252021-08-262021-08-272021-08-282021-08-292021-08-302021-08-312021-09-012021-09-022021-09-032021-09-042021-09-292021-09-302021-10-022021-10-05Leidos warrants only that the survey data acquired by Leidos and delivered to NOAA under Contract 1305M220DNCNJ0056 reflects the state of the sea floor in existence on the day and at the time the survey was conducted. H13504 was surveyed in accordance with the following documents: 1. 1305M221FNCNJ0270 signed.pdf, received 08 June 2021 2. Hydrographic Survey Specifications and Deliverables (HSSD), April 2021 3. OPR-K380-KR-21_PRF_FINAL_05032021.000, received 08 June 2021 4. OPR-K380-KR-21_CSF_FINAL_05032021.000, received 08 June 2021 5. OPR-K380-KR-21 Project Brief, held 24 June 2021 6. OPR-K380-KR-21 and OPR-K380-KR-21 feature guidance follow-up.pdf, 30 July 2021 7. 1305M221FNCNJ0270 - Modification P21001.pdf received 11 August 2021The entire survey is adequate to supersede previous data.SupportFiles\H13504_Figure_02.pngFinal Bathymetry Coverage for H13504SupportFiles\H13504_Figure_03.pngFinal Side Scan Coverage for H13504 (First 100% Coverage)SupportFiles\H13504_Figure_04.pngFinal Side Scan Coverage for H13504 (Second 100% Coverage)H13504 was located 10NM SSW from Freeport, Texas; with southern extents approximately 10.2km offshore continuing north to approximately 10.7km offshore of Freeport, TX (Figure 1). The survey was conducted in accordance with coverage requirements listed in the Project Instructions. 95.48620428.86983395.1750528.677908SupportFiles\H13504_Figure_01.pngH13504 Survey BoundsSurvey limits were acquired in accordance with the requirements in the Project Instructions and the Hydrographic Survey Specifications and Deliverables (HSSD), April 2021.Atlantic Hydrographic BranchAny revisions to the Descriptive Report (DR) applied during office processing are shown in red italic text. The DR is maintained as a field unit product, therefore all information and recommendations within this report are considered preliminary unless otherwise noted. The final disposition of survey data is represented in the NOAA nautical chart products. All pertinent records for this survey are archived at the National Centers for Environmental Information (NCEI) and can be retrieved via https://www.ncei.noaa.gov/. Products created during office processing were generated in NAD83 UTM 15N, MLLW. All references to other horizontal or vertical datums in this report are applicable to the processed hydrographic data provided by the field unit.Basic Hydrographic SurveymetersMultibeam Echo Sounder BackscatterSide Scan SonarMultibeam Echo Sounder2021-10-052021-08-18UTC20212021-05-13Bridget W. BernierContractor10NM SSW from Freeport2United StatesTexas10000H13504Port Freeport and Approaches, TXOPR-K380-KR-21LeidosWestern Gulf of MexicoData Processing Manager2022-02-07Bridget W. Bernier2021-11-05OPR-K380-KR-21 Final Project Summary Report.pdf2021-11-22OPR-K380-KR-21_ Marine_Species_Awareness_Training_Record.pdf2021-11-30OPR-K380-KR-21_Coast Pilot Review Report.pdf 2022-01-21OPR-K380-KR-21_DAPR.pdf2022-01-21H13502_DR.pdf2022-02-01OPR-K380-KR-21_20220201.zip (NCEI Sound Speed Data)2022-02-03OPR-K380-KR-21 Marine Mammal Sighting Forms.pdf2022-02-07H13503_DR.pdfThis 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 Hydrographic Survey Specifications and Deliverables, Project Instructions, and Statement of Work. These data are adequate to supersede charted data in their common areas. This survey is complete and no additional work is required. Previously, or concurrently, submitted deliverables for OPR-K380-KR-21 are provided in the table below.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.There were no assigned channels within the H13504 SOW from the final CSF. However, the survey area was coincident to Safety Fairway (FAIRWY) to the Freeport Harbor Channel (ENC US4TX41M and US5POBC), H13502 CUBE depths were in agreement with the charted depths.Chart comparisons were conducted using a combination of SABER and CARIS’ HIPS and SIPS. H13504 data meet data accuracy standards and bottom coverage requirements. Leidos recommends updating the common areas of all charts using data from this survey. Review showed that the H13504 depth data were generally in good agreement (primarily within ±0.5 meters) with charted depths compared to the ENCs listed in Section D.1.1. Charting recommendations for new features and updates to charted features, are documented in the H13504 S-57 FFF. Additional charted objects are discussed in later sections. United States Coast Guard (USCG) District 8 LNM publications were reviewed for changes subsequent to the date of the Project Instructions and before the end of survey. The LNM reviewed were from week 23/21 (09 June 2021) until week 04/22 (26 January 2022).There were numerous assigned charted features in the final CSF (OPR-K380-KR-21_CSF_FINAL_05032021.000) within the SOW of H13504. Per HSSD Section 8.1.4, these charted features are not addressed in this section; refer to the H13504 S-57 FFF (H13504_FFF.000) for all the details and recommendations regarding these features. Within the FFF there are several charted obstructions which Leidos covered and identified within the H13504 data, however the objects are not recommended for charting as obstructions. Rather, they are recommended to be charted as a soundings and contours, as Leidos identified the obstructions to be coral outcroppings. These coral outcroppings were found to cover large areas within H13504, intermittently spanning across the middle of the sheet’s SOW area. In all cases where observed, these coral outcroppings were found to be appropriately captured by CUBE (Figure 15). In addition to the assigned features within the CSF there were several unassigned objects. The DMPGRD (dumping ground) area charted on ENCs US5POBB, US5POBC, and US4TX41M was a particularly dynamic area and exhibited several piles of sediment (Figure 16). Within this area were multiple objects with heights of approximately 1-meter. While the objects met the criteria to be a feature as defined in the HSSD with a 1-meter height; a feature over-ride was not set on all of these observed features within the DMPGRD as the controlling depths within the surrounding area were from the sediment mounds. The sediment mounds were characterized as natural and Leidos utilized HSSD Section 7.3.2 for determining if a feature over-ride was necessary. CUBE depths honored the sediment mounds within 0.5-meter TVU, therefore no feature over-rides were set on sediment mounds either. The DMPGRD is not retained within the FFF per the investigation requirements from the CSF. SSS contacts associated with the coral outcropping and within the DMPGRD were retained within the H13504 Side Scan Sonar Contact S-57 file (H13504_SSS_Contacts.000).SupportFiles\H13504_Figure_15.pngCoral Outcroppings within H13504 MBES CoverageSupportFiles\H13504_Figure_16.pngENC US4TX41M DMPGRD with H13504 MBES CoverageSee the H13504 S-57 FFF for all the details and recommendations regarding new uncharted features investigated.Figure 14 details the Leidos submitted DTON and Anti-DTON reports for H13504. Reports were submitted per HSSD in S-57 format to the Atlantic Hydrographic Branch (AHB). DTON 02 was not forwarded by AHB for immediate charting. Refer to the Project Correspondence for email correspondence related to submitted files.SupportFiles\H13504_Figure_14.pngDTON ReportsBWBUS5POBB ENC US5POBB is coincident to H13504. CUBE depths within H13504 agreed well with the charted depths across the contemporaneous survey area; observed depths were primarily within ±0.5 meters of charted depths. US5POBC ENC US5POBC is coincident to H13504. CUBE depths within H13504 agreed well with the charted depths across the contemporaneous survey area; observed depths were primarily within ±0.5 meters of charted depths. The charted depth contour generally agreed with depths that fell within the H13504 survey area. US4TX41M ENC US4TX41M is coincident to H13504. CUBE depths within H13504 agreed well with the charted depths across the contemporaneous survey area; observed depths were primarily within ±0.5 meters of charted depths. The charted depth contours generally agreed with depths that fell within the H13504 survey area. US5FPOBB2020-06-152022-01-05110000US5FPOBC2021-09-272022-01-05310000US4TX41M2021-09-272022-01-052180000Platforms were assigned from the CSF and are addressed in the H13504 FFF.No Maritime Boundary Points were assigned for this survey.No new ENC recommendations are made for the area surrounding this survey area.No new survey recommendations are made for the area surrounding this survey area.In accordance with both the Project Instructions and Section 7.2.3 of the HSSD, bottom characteristics were obtained for H13504. Bottom characteristics were acquired at the eight locations assigned in the final PRF (OPR-K380-KR-21_PRF_FINAL_05032021.000). Leidos did not modify the bottom sample locations from the locations proposed by NOAA in the PRF. Bottom characteristics are included in the S-57 FFF. In addition, images of the sediment obtained for each bottom sample are referenced in the S-57 FFF and are included on the delivery drive under the folder H13504/Processed/Multimedia.No construction or dredging exists for this survey area.There were no overhead features within this survey area.Within the final CSF there were several assigned submarine features (cables and pipelines) for investigation. Within the H13504 data Leidos classified three additional features as exposed pipelines based on their characteristics and size in MBES and SSS data. These pipelines fell outside of charted pipeline or cable areas (Features 04, 07, and 09). Feature 04 was exposed approximately 2-meters above the surrounding depth area which Leidos submitted as DTON 01, following HSSD Section 1.7.2. The remaining two exposed pipelines were approximately 0.3m higher than the surrounding depth area, determined to be non-dangerous and were submitted to NOAA following HSSD Section 1.7.3. In accordance with Project Instructions, dated 06 July 2021, exposed or unburied pipelines were to be submitted to Texas General Land Office of Texas (GLO) as a .KMZ file if the data fell within the bounds of the State of Texas Coastal Zone Management Area (CZMA), in place of HSSD Section 1.7.1. The three identified exposed pipelines fell within the TX CZMA and Leidos submitted the .KMZ file to TX GLO; refer to Project Correspondence. Charted assigned submarine features were not observed in H13504 to be exposed or unburied, refer to the H13504 S-57 FFF. The CSF investigation requirements for the submerged cables (CBLSUB) listed “Visually confirm feature object existence. If discrepancy, discuss in DR (see HSSD Section 8.1.4). Do not include feature in FFF.” No sections of charted cables were observed within the H13504 MBES or SSS data therefore the CBLSUB are not discussed within the H13504 S-57 FFF. SSS contacts associated with the submarine features were retained within the H13504 Side Scan Sonar Contact S-57 file (H13504_SSS_Contacts.000).No abnormal seafloor or environmental conditions, as defined in Section 8.1.4 of the HSSD, exist within this survey area other than those discussed in Section B.2.6.No ferry routes or terminals exist within this survey area.There was one assigned Aid to Navigation (ATON) within the SOW of H13504 within the final CSF. During survey, this BOYSPP (George Vancouver Liberty Ship Reef Buoy FR-TX-5) was not found to be present. Per HSSD Section 1.6.2.2 as the ATON was listed in the USCG Light List, Leidos submitted an ATON Discrepancy Report to the USCG and forwarded to NOAA. LNM 47/21 (24 November 2021) subsequently noted the ATON as MISSING. This assigned BOYSPP is documented within the H13504 FFF. No other ATONs were present within the bounds of the H13504 survey limits.Within the acquired H13504 MBES and SSS data instances of dense biological interference were observed during discrete areas on various days of survey which required numerous holiday fill lines. Throughout survey acquisition sport fishing and commercial shrimping via trawls were common within the H13504 survey bounds. These observances did not have any significant impact on the final CUBE surface.Biological InterferenceMultibeam echo sounder crosslines acquired for this survey totaled 4.66% of mainscheme acquisition. The resulting crossline to mainscheme percentage met the requirement to achieve approximately four percent of mainscheme mileage for a Complete Coverage multibeam survey (Section 5.2.4.2 of the HSSD). H13504 requirements were for Complete Coverage, Option B, based on the classifications defined in Section 5.2.2.3 of the HSSD. The mainscheme lines were spaced 80 meters apart. Crosslines were generally spaced 2,000 meters apart based on line spacing and linear nautical miles of each survey area. In the field, hydrographers conducted daily comparisons of mainscheme to near nadir crossline data to ensure that no systematic errors were introduced and to identify potential problems with the survey systems. After the application of all correctors and completion of final processing in the office, separate CUBE PFM grids were built at 1-meter resolution. One grid contained the full valid swath (±65° from nadir, Class 2) of mainscheme multibeam and the other included only the near nadir swath (±5° from nadir, Class 1) crossline data. The difference grid was created by subtracting the 1-meter H13504 mainscheme CUBE depths from the 1-meter H13504 crossline CUBE depths. The SABER Frequency Distribution Tool was used to analyze the difference grid created from the mainscheme and crossline PFM grids and the results of the analysis were compiled into the following section. Section 5.2.4.2 of the HSSD states that the depth difference values are to be within the maximum allowable TVU, which for the range of depths observed in the crossline PFM comparison area (12.868 to 20.082 meters) was calculated to be between 0.527 to 0.564 meters. Comparisons of the final crossline data versus final mainscheme data showed that 99.99% of comparisons were within 0.300 meters or less within the calculated allowable TVU ranges (Figure 6). A single difference exceeded the maximum TVU, 0.608 meters, which was due steep slope. The distribution is spread about zero for all comparisons as presented in Figure 7.SupportFiles\H13504_Figure_06.pngTabular Results Crossing Analysis, Crosslines vs. Mainscheme LinesSupportFiles\H13504_Figure_07.pngPlot of Crossing Analysis Crosslines vs. Mainscheme LinesSonar system quality control checks were conducted as detailed in the DAPR.On the M/V Atlantic Surveyor, the MVP30 was the primary system used to collect sound speed profile (SSP) data, refer to the DAPR for additional details. SSP data were obtained at intervals frequent enough to meet depth accuracy requirements. Section 5.2.3.3 of the HSSD requires that if the sound speed measured at the sonar head differs by more than two meters/second from the commensurate profile data, then another cast shall be acquired. All sound speed profiles applied for online bathymetry data collection were acquired within 500 meters of the bounds of the survey area as specified in Section 5.2.3.3 of the HSSD. Confidence checks of the sound speed profile casts were routinely conducted by comparing at least two consecutive casts taken with different SSP sensors. All individual SSP files are delivered with the H13504 data and are broken out into sub-folders, which correspond to the purpose of each cast. Also, all individual SSP files for H13504 have been concatenated into two separate files based on the purpose of the cast, provided in CARIS format files (.svp), and delivered under (H13504/Processed/SVP/CARIS_SSP) on the delivery drive. In accordance with HSSD Section 8.3.6, SSP files were also converted to NCEI format, as detailed in the DAPR, and provided as a separate delivery to NCEI. Refer to the DAPR for additional details.There were no conditions or deficiencies that affected equipment operational effectiveness.None ExistAll equipment and survey methods are detailed in the DAPR.As stated in Section A.4, H13504 was assigned as Complete Coverage; Leidos chose to achieve the coverage requirement following Option B (100% side scan sonar coverage with concurrent multibeam bathymetry). To achieve this coverage, the SSS was set to 50-meter range scale, and main scheme survey lines were spaced at 80-meters to ensure 100% SSS coverage. Disproval areas were covered with either 100% multibeam coverage or 200% side scan coverage. The SABER Gapchecker program was used to flag MBES data gaps within the CUBE surface. Additionally, the entire surface was visually scanned for holidays at various points during the data processing effort. Additional survey lines were run to fill any holidays that were detected. Bathymetric data and side scan sonar imagery were reviewed and bathymetric splits were acquired if deemed necessary per Hydrographer’s discretion, as noted in Section 5.2.2.1 of the HSSD. A final review of the CUBE Depth surface of the H13504 1-meter PFM showed that there were no holidays as defined for complete coverage surveys in Section 5.2.2.3 of the HSSD. Any remaining three by three unpopulated nodes in the final MBES surfaces were along the outer swath data, outside of the SSS nadir coverage gap, and was fully covered with 100% SSS coverage. The final H13504 CUBE PFM grid was examined for the number of soundings contributing to the chosen CUBE hypotheses for each node by running SABER’s Frequency Distribution Tool on the Hypothesis Number of Soundings (Hyp. # Soundings) surface. The Hyp. # Soundings surface reports the number of soundings that were used to compute the chosen hypothesis. Analysis was conducted on the Hyp. # Soundings surface from the PFM grid to ensure that the requirements for complete coverage surveys, as specified in HSSD Section 5.2.2.3 were met. Within the final 1-meter PFM grid, 99.20% of all nodes contained five or more soundings.Multibeam Coverage Analysis Per the Project Instructions, junction analysis was performed between H13504 and the surveys listed in the table below. Figure 9 shows the general locality of H13504 as it relates to the sheets against which junctions were performed. Analysis of H13504 to H13505 and H13506 will be provided within those respective Descriptive Reports as final analysis and processing efforts for H13505 and H13506 remain on-going. Analysis between H13504 to H13502 and H13503 are discussed below.Junctioning survey H13502 was conducted in 2021 and junctions to the north of H13504. For this analysis the H13502 50-centimeter CUBE depth surface was compared to the H13504 1-meter CUBE depth surface. Junction analysis was conducted on the common area of these two sheets, with an overlapping area of approximately 150-1500 meters. Observed depths within the common area were 17.392 to 147.784 meters which resulted in a calculated allowable TVU range of 0.549 to 0.551 meters. The difference grid was generated by subtracting the H13502 data from the H13504 data. Positive values indicate that H13504 depth data were deeper than H13502 depth data. Throughout the common area, H13504 CUBE depths were deeper than H13502 13.12% of the time and were shoaler than H13502 86.39% of the time (Figure 10). The distribution is spread about zero for all comparisons as presented in Figure 11. 100.00% of the comparisons were 0.287 meters or less, within the calculated allowable TVU range.N2021H13502Leidos, Inc.5000SupportFiles\H13504_Figure_10.pngTabular Results Junction Analysis H13504 vs. H13502SupportFiles\H13504_Figure_11.pngPlot of Junction Analysis H13504 vs. H13502Junctioning survey H13503 was conducted in 2021 and junctions to the north of H13504. For this analysis the H13503 1-meter CUBE depth surface was compared to the H13504 1-meter CUBE depth surface. Junction analysis was conducted on the common area of these two sheets, with an overlapping area approximately 180-29,490 meters. Observed depths within the common area were 13.861 to 17.744 meters which resulted in a calculated allowable TVU range of 0.531 to 0.551 meters. The difference grid was generated by subtracting the H13503 data from the H13504 data. Positive values indicate that H13504 depth data were deeper than H13503 depth data. Throughout the common area, H13504 CUBE depths were deeper than H13503 47.25% of the time and were shoaler than H13503 51.58% of the time (Figure 10). The distribution is well spread about zero for all comparisons as presented in Figure 11. 100.00% of the comparisons were 0.298 meters or less, within the calculated allowable TVU range.N2021H13503Leidos, Inc.5000SupportFiles\H13504_Figure_12.pngTabular Results Junction Analysis H13504 vs. H13503SupportFiles\H13504_Figure_13.pngPlot of Junction Analysis H13504 vs. H13503SupportFiles\H13504_Figure_09.pngGeneral Locality of H13504 with Junctioning SurveysFor specific details on the use and application of the SABER Total Propagated Uncertainty (TPU) model, refer to the DAPR. Once the TPU model was applied to the GSF bathymetry data, each beam was attributed with the horizontal uncertainty and the vertical uncertainty at the 95% confidence level. The vertical and horizontal uncertainty values, estimated by the TPU model for individual multibeam soundings, varied little across the dataset, tending to be most affected by beam angle. Individual soundings that had vertical and horizontal uncertainty values above IHO S-44 6th Edition, Order 1a were flagged as invalid during the uncertainty attribution. As discussed in the DAPR, SABER generates two vertical uncertainty surfaces; the Hypothesis Standard Deviation (Hyp. StdDev) and the Hypothesis Average Total Propagated Uncertainty (Hyp. AvgTPU). A third vertical uncertainty surface is generated from the larger value of these two uncertainties at each node and is referred to as the Hypothesis Final Uncertainty (Hyp. Final Uncertainty). Per HSSD Section 5.2.2.2, H13504 depth data fell within a single grid resolution at 1-meter. The final H13504 1-meter PFM CUBE surface contained final vertical uncertainties that ranged from 0.210 meters to 1.029 meters. The IHO Order 1a maximum allowable vertical uncertainty was calculated to range between 0.520 to 0.569 meters, based on the minimum CUBE depth (10.959 meters) and maximum CUBE depth (20.939 meters). Results from the SABER Check PFM Uncertainty function identified that there were 324 nodes in the final H13504 1-meter PFM CUBE surface with final vertical uncertainties that exceeded IHO Order 1a allowable vertical uncertainty. These nodes were all associated with features, particularly within the bounds of the charted fish haven area, and in areas of steep slopes along the coral outcroppings. The SABER Frequency Distribution Tool was also used to review the Hyp. Final Uncertainty surface within the final H13504 1-meter PFM grid. Results showed that 99.99% of all nodes had final uncertainties less than or equal to maximum allowable vertical uncertainty of 0.360 meters, which was below the allowable calculated TVU range.1.01.01.01.0M/V Atlantic Surveyor0.20ERS via VDATUM0.093SupportFiles\H13504_Figure_08.pngExample Nodes in H13504 1-meter CUBE surface with Uncertainty Exceeding (Blue Symbols) IHO Along SlopesComplete Coverage Section 5.2.2.3 of the HSSD requires 1-meter node resolution for depths ranging from 0 meters to 20 meters. Leidos generated the CUBE PFM grid for H13504 at 1-meter resolution. SABER populates the CUBE depth with either the node’s chosen hypothesis or the depth of a feature or designated sounding set by the hydrographer, which overrides the chosen hypothesis. The range of CUBE depths of the H13504 1-meter PFM grid were from 10.959 meters (35.955 feet; 0.223 meters Total Vertical Uncertainty [TVU]) to 20.939 meters (68.697 feet; 0.210 meters TVU). In the northeast corner of the H13504 survey limits there is an area of approximately 392 meters by 2,736 meters which has resulting CUBE depths deeper than 20 meters. HSSD requirements for node resolution were met at 1-meter node resolution within these depths and therefore these depths deeper than the HSSD 1-meter resolution are retained within the delivered Final 1-meter surface. The final gridded bathymetry data are delivered as a Bathymetric Attributed Grid (BAG). The BAG file was exported from the CUBE PFM grid as detailed in the DAPR. Complete Coverage, Option B (100% side scan sonar coverage with concurrent multibeam)10.95920.939H13504_MB_1m_MLLW_FinalBAG1N/AFirst 100% SSS00H13504_SSSAB_1m_400kHz_1of1SSS Mosaic (.tif)1N/ASecond 100% SSS (Disproval coverage)00H13504_SSSAB_1m_400kHz_2of2SSS Mosaic (.tif)1N/ANOAA Profile Version 2021Leidos5.4.1.5.5SABERLeidos5.4.1.5.5SABERThe primary data processing software used for both bathymetry and imagery was SABER. All data reduction procedures conform to those detailed in the DAPR.All sounding systems were calibrated as detailed in the DAPR. Multibeam files associated with calibration were listed within the OPR-K380-KR-21 DAPR; the DAPR and calibration data were previously delivered with H13502.Side Scan Sonar (SSS) Coverage Analysis: For all details regarding SSS data processing, see the DAPR. Leidos chose to adhere to the coverage requirements in the Project Instructions using Complete Coverage, Option B (100% side scan sonar coverage with concurrent multibeam). Leidos generated two separate coverage mosaics at 1-meter cell size resolution as specified in Section 8.2.1 of the HSSD (See section B.2.9 for additional information). The first 100% and second 100% coverage mosaics were independently reviewed using tools in SABER to verify data quality and swath coverage. The SABER Gapchecker routine was used to flag data gaps within each of the 100% SSS coverage mosaics. Additionally, the entirety of each SSS surface was visually scanned for holidays at various points during the data processing effort. Additional survey lines were run to fill any holidays that were detected. Both coverage mosaics are determined to be complete and sufficient to meet the requirements contained within the Project Instructions and HSSD. Each 100 percent coverage mosaic is delivered as a single georeferenced raster file (datum of NAD83) in floating point GeoTIFF format, as specified in Sections 8.2.1 and 8.3.3 in the HSSD. Multibeam Echo Sounder Seafloor Backscatter: Leidos collected MBES backscatter data with all GSF data acquired, in accordance with HSSD Section 6.2. The MBES settings used were checked to ensure acceptable quality standards were met and to mitigate acoustic saturation of the backscatter data. The MBES backscatter data acquired were written to the GSF in real-time by ISS-2000 and are delivered in the final GSF files for this sheet. Evaluation of backscatter data and processing were not required for OPR-K380-KR-21 and therefore no additional processing was performed by Leidos and no additional products were produced.Leidos used their ISS-2000 software on a Windows platform to acquire these survey data. Survey planning and data analysis were conducted using the Leidos SABER software on Linux platforms. Side scan sonar (SSS) data were collected on a Windows platform using Klein’s SonarPro software. Subsequent processing and review of the SSS data, including the generation of coverage mosaics, were accomplished using SABER. A detailed description of the systems and vessels used to acquire and process these data is included in the Data Acquisition and Processing Report (DAPR) for OPR-K380-KR-21, delivered previously with H13502. There were no variations from the equipment configuration described in the DAPR.SeaBat T50-RTeledyne RESONMBESSystem 4000Klein Marine SystemsSSSPOS MV 320 v5ApplanixPositioning and Attitude SystemMVP30AML OceanographicSound Speed SystemA detailed description of the equipment installed is included in the DAPR.9110M/V Atlantic SurveyorSupportFiles\H13504_Figure_05.pngM/V Atlantic SurveyorThe M/V Atlantic Surveyor (Figure 5) was used to collect multibeam echo sounder (MBES) (RESON SeaBat T50), side scan sonar (SSS) (Klein 4000), and sound speed data during twenty-four hours per day survey operations. A detailed description of the vessel used is included in the DAPR.