OPR-E351-KR-22 Southwest Chesapeake Bay Rivers Southwest Chesapeake Bay eTrac H13768 4 Burwell Bay through Jones Neck Virginia United States 10000 2023 David Neff, C.H. Basic Hydrographic Survey 2023-03-08 2023-04-11 2024-02-08 Multibeam Echo Sounder Multibeam Echo Sounder Backscatter Side Scan Sonar meters UTC Atlantic Hydrographic Branch All times are UTC. The purpose of this survey is to update existing NOS nautical charts. H13768 covers approximately 52 square nautical miles of the James River from Burwell Bay through Jones Neck, Virginia. Any revisions to the Descriptive Report (DR) applied during office processing are shown in red italic text. The DR is maintained as a field unit product, therefore all information and recommendations within this report are considered preliminary unless otherwise noted. The final disposition of survey data is represented in the NOAA nautical chart products. All pertinent records for this survey are archived at the National Centers for Environmental Information (NCEI) and can be retrieved via https://www.ncei.noaa.gov/. Products created during office processing were generated in NAD83 UTM 18N, MLLW. All references to other horizontal or vertical datums in this report are applicable to the processed hydrographic data provided by the field unit. CC0-1.0 (NOAA Contractors) CC0-1.0 https://creativecommons.org/publicdomain/zero/1.0/ https://creativecommons.org/publicdomain/zero/1.0/legalcode These data were produced under contract with NOAA and any potential copyright was assigned to NOAA. NOAA waives any potential copyright and related rights in these data worldwide through the Creative Commons Zero 1.0 Universal Public Domain Dedication (CC0). Contractor eTrac conducted hydrographic survey operations in the James River, Virginia. H13768 covers approximately 52 square nautical miles of survey area. 2097.96 linear nautical miles were acquired during the survey. Survey was conducted within these limits between April 11, 2023 (DN101) and February 8, 2024 (DN039). 37.406844444444445 77.33039722222222 37.040188888888885 76.58704999999999 All data were acquired in accordance with the requirements in the Hydrographic Survey Project Instructions and specifications set forth in the Hydrographic Survey Specifications and Deliverables 2022 Edition (HSSD 2022). Survey Limits Overview (light blue area) file:///H:/OPR-E351-KR-22/Surveys/H13768/01_HDR/Reports/Descriptive_Report/SupportFiles/H13768_SurveyLimits_Overview.png Survey Limits (black line) file:///H:/OPR-E351-KR-22/Surveys/H13768/01_HDR/Reports/Descriptive_Report/SupportFiles/H13768_SurveyLimits.png The principal objective of the Southwest Chesapeake Bay Rivers project is manifold. This survey will supply forecasters and decision makers at the NOAA National Water Center with bathymetric data for critical hydrodynamic modeling. This data is necessary to understand the timing of rapid river stage increases and decreases, the duration of high water, inundation, or drought. This data will support hydrodynamic models that predict movement of oil and hazardous materials along the heavily industrialized James River. This survey will emphasize features that effect safe navigation and update the Office of Coast Survey nautical charts and services The entire survey is adequate to supersede previous data. Survey H13768 is accurate to International Hydrographic Organization (IHO) Order 1a as required per the HSSD 2022. All waters in survey area Complete Coverage Option B All waters in survey area 2 to 8 m water depth Sidescan Sonar Data may be aquired at an altitude of 6-20% of the range-scale All waters in survey area in which a side scan sonar contact indicates a natural feature, i.e. mounds, with height greater than 1 meter. 1) Inside the traffic corridor and in areas of low under keel clearance, investigate all contacts to complete coverage standards in accordance with HSSD requirements. 2) Outside the traffic corridor, if discrete features are located within 8 mm at the largest scale chart, then the most significant feature within the 8 mm radius should be investigated (with 2 investigation lines perpendicular to each other). Survey coverage was in accordance with the requirements listed above and in the HSSD 2022. Note: Survey coverage did not extend to the entire survey boundary as the Navigable Area Limit Line (NALL) was reached or low value to mariner (using our NALL decision tree). However there are occasionally small gaps in the side scan mosaic along the NALL due to the inability to safely tow the side scan up to the NALL which would require operating the vessel beyond the NALL. Gaps in complete survey coverage exist due to the presence of moored ships. Many of these ships are associated with the James River Reserve Fleet in proximity to the Fort Eustis Military Reservation. An example of a coverage gap due to moored ships is presented below. Gaps in complete survey coverage exist due to areas where the NALL was established for safety concerns and low value to the mariner (Using our NALL decision tree - Appendix 2). An example of a coverage gap due to safety is presented below. Survey Coverage with combined MBES and SSS file:///H:/OPR-E351-KR-22/Surveys/H13768/01_HDR/Reports/Descriptive_Report/SupportFiles/H13768_SurveyCoverage_MBES_SSS.png Survey Coverage Gap due to Moored Ships file:///H:/OPR-E351-KR-22/Surveys/H13768/01_HDR/Reports/Descriptive_Report/SupportFiles/H13768_DataCoverageGap_Moored_Ships.png Survey Coverage Gap due to NALL Safety file:///H:/OPR-E351-KR-22/Surveys/H13768/01_HDR/Reports/Descriptive_Report/SupportFiles/H13768_DataCoverageGap_NALL_Safety.png R/V Endeavor 0.0 0.0 0.0 0.0 0.0 314.14 0.0 0.0 0.0 R/V Pulse 0.0 0.0 0.0 0.0 0.0 1344.24 0.0 57.58 0.0 R/V Spectrum 0.0 0.0 0.0 0.0 0.0 217.96 0.0 25.85 0.0 R/V Voxel 0.0 0.0 0.0 0.0 0.0 59.69 0.0 0.0 0.0 R/V 505 0.0 0.0 0.0 0.0 0.0 78.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2014.53 0.0 83.43 0.0 4.14 14 0 0 0 52.0 2023-04-11 2023-04-12 2023-04-14 2023-04-16 2023-04-17 2023-04-18 2023-05-03 2023-05-04 2023-05-05 2023-05-06 2023-05-07 2023-05-26 2023-05-28 2023-05-29 2023-05-30 2023-05-31 2023-06-01 2023-06-02 2023-06-03 2023-06-04 2023-06-05 2023-06-06 2023-06-07 2023-06-08 2023-06-09 2023-06-10 2023-06-11 2023-06-12 2023-06-13 2023-06-14 2023-06-15 2023-06-16 2023-06-17 2023-06-18 2023-06-19 2023-06-20 2023-06-22 2023-06-23 2023-06-24 2023-06-25 2023-06-26 2023-07-12 2023-07-13 2023-07-15 2023-07-16 2023-07-17 2023-07-18 2023-07-19 2023-07-20 2023-07-21 2023-07-22 2023-07-23 2023-07-25 2023-07-26 2023-07-27 2023-07-28 2023-07-29 2023-07-30 2023-08-01 2023-08-02 2023-08-03 2023-08-05 2023-08-06 2023-08-09 2023-08-11 2023-08-12 2023-08-13 2023-10-01 2023-10-02 2023-10-03 2023-10-04 2023-10-05 2023-10-06 2023-10-09 2023-10-10 2023-10-27 2023-10-28 2023-10-29 2023-11-02 2023-11-03 2023-11-04 2023-11-05 2023-11-06 2023-11-07 2023-11-08 2023-11-09 2023-11-10 2023-11-11 2023-11-12 2023-11-13 2023-11-14 2023-11-15 2023-11-16 2023-11-17 2023-11-19 2023-11-20 2023-11-28 2023-11-29 2023-11-30 2023-12-01 2023-12-02 2023-12-15 2023-12-16 2024-02-08 Section A.5 is being registered as A.6 when the XML is printed to PDF ISK Refer to the 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 are discussed in the following sections. R/V Endeavor 13.4 0.8 R/V Pulse 7.3 0.6 R/V Spectrum 6.7 0.6 R/V Voxel 14.0 0.6 R/V 505 10.0 0.6 The R/V Endeavor is a 13.4 meter aluminum catamaran built by Armstrong Marine equipped with an over-the-side Pitman Arm Sonar Mount with a secondary tie point, a hydraulic A-frame and davit. The R/V Pulse is a 7.3 meter aluminum monohull equipped with a Universal Sonar Mount (USM) starboard multibeam pole mount and davit. The R/V Spectrum is a 6.7 meter aluminum monohull equipped with a Universal Sonar Mount (USM) starboard multibeam pole mount and davit. The R/V Voxel is a 14.0 meter aluminum catamaran built by Armstrong Marine equipped with an electro hydraulic actuated moonpool accessed adjustable aluminum and stainless steel custom mount and hydraulic A-frame. The R/V 505 is a 10 meter aluminum catamaran equipped with a Universal Sonar Mount (USM) starboard multibeam pole mount and davit. MBES R2Sonic 2024 MBES R2Sonic 2022 Sound Speed System AML Oceanographic 3-RT Velocity Probe Sound Speed System AML Oceanographic MicroX SV Sound Speed System AML Oceanographic AML-3 LGR Sound Speed System AML Oceanographic BaseX2 Positioning and Attitude System Applanix POS MV WaveMaster Positioning and Attitude System Applanix POS MV OceanMaster Positioning System R2Sonic I2NS SSS EdgeTech 4125 SSS EdgeTech 4200 Note: R/V Endeavor utilized a single head R2Sonic 2024 multibeam echosounder system (MBES) with the exception of October 2023 when R/V Endeavor utilized a dual head R2Sonic 2022 MBES. R/V Endeavor also utilized an AML 3-RT for the surface sound speed system, an AML-3 LGR for the sound speed system, an R2Sonic I2NS for the positioning and attitude system, and an EdgeTech 4200 MP side scan sonar (SSS). R/V Pulse utilized a single head R2Sonic 2024 multibeam echosounder system (MBES), an AML 3-RT for the surface sound speed system, an AML-3 LGR for the sound speed system, an Applanix POSMV WaveMaster (POS MV 320 v4) for the positioning and attitude system, and an EdgeTech 4125 side scan sonar (SSS). R/V Spectrum utilized a single head R2Sonic 2024 multibeam echosounder system (MBES), an AML Micro.X for the surface sound speed system, an AML Base.X2 for the sound speed system, an Applanix POSMV WaveMaster (POS MV 320 v4) for the positioning and attitude system, and an EdgeTech 4125 side scan sonar (SSS). R/V Taku utilized a single head R2Sonic 2024 multibeam echosounder system (MBES), an AML 3-RT for the surface sound speed system, an AML Base.X2 for the sound speed system, an Applanix POSMV OceanMaster (POS MV 320 v5) for the positioning and attitude system, and an EdgeTech 4125 side scan sonar (SSS). R/V Voxel utilized a single head R2Sonic 2024 multibeam echosounder system (MBES), an AML 3-RT for the surface sound speed system, an AML-3 LGR for the sound speed system, an Applanix POSMV OceanMaster (POS MV 320 v5) for the positioning and attitude system, and an EdgeTech 4125 side scan sonar (SSS). R/V 505 utilized a single head R2Sonic 2022 multibeam echosounder system (MBES), an AML Micro.X for the surface sound speed system, an AML Base.X2 for the sound speed system, an Applanix POSMV OceanMaster (POS MV 320 v5) for the positioning and attitude system, and an EdgeTech 4125 side scan sonar (SSS). A beam-to-beam statistical analysis was performed using the Cross Check tool in Qimera. A 1 meter Combined Uncertainty and Bathymetric Estimator (CUBE) weighted dynamic surface was created incorporating only the mainscheme lines and excluded crosslines. The Cross Check tool was used to perform the beam-by-beam comparison of the crossline data to the mainscheme surface. Comparisons showed excellent agreement, well above 95% of the allowable TVU. The percentage of crossline miles as compared to main scheme miles was 4.14% Note: This surface was created for QC only and is not submitted as a surface deliverable. Below is a histogram of the crossline comparison statistics showing IHO Order 1a compliance per beam. H13768 Crossline Comparison file:///H:/OPR-E351-KR-22/Surveys/H13768/01_HDR/Reports/Descriptive_Report/SupportFiles/H13768_CrossCheck.jpg ERS via ERTDM 0.06 R/V Endeavor 0.05 0.2 R/V Pulse 0.05 0.2 R/V Spectrum 0.05 0.2 R/V Voxel 0.05 0.2 R/V 505 0.05 0.2 The standard deviation uncertainty and the total vertical uncertainty (TVU) layers of the Dynamic Surface were utilized during data processing to search for features, water column noise, and systematic errors. IHO Order 1a uncertainty specification was met by 100% of the nodes. In Qimera versions beginning in 2.5.1 and beyond, the user has the ability to export the Dynamic Surface to a Bathymetric Attributed Grid (BAG) with TVU represented in the uncertainty layer. Using this BAG, the percentage of nodes that fell within the TVU specification for each Dynamic Surface was calculated using the NOAA QC tools program. These results are shown in an image below. Complete Coverage Option B MBES (Finalized 1m CUBE weighted Dynamic Surface in NOAA QC Tools) = 100% of nodes are within the allowable TVU. H13768 Finalized 1m MBES TVU Statistics file:///H:/OPR-E351-KR-22/Surveys/H13768/01_HDR/Reports/Descriptive_Report/SupportFiles/H13768_MB_1m_MLLW_Final_TVU.png Depth differences between junctioning surveys were evaluated using the JunctionTrac program, developed in-house by eTrac. For each junction, each CUBE weighted dynamic surface's nodes were exported to an ASCII CSV file where the fields were (Easting, Northing, Depth) for each node. A 1 meter difference surface between the junctioning datasets was also created and exported to an ASCII CSV file where the fields were (Easting, Northing, Diff) for each node. The three ASCII CSV files were then loaded into the JunctionTrac program and junction statistics were computed. A file was also created in this process to locate any nodes from the difference surface that exceed the allowable TVU, which was imported into Qimera and any identified points from JunctionTrac were analyzed. Note: the difference surfaces were created for comparison efforts only and are not submitted as surface deliverables. H13769 5000 2023 eTrac SE The junction comparison was performed using all overlapping data between H13768 and H13769. Below is a histogram of junction comparison statistics showing the difference between the junctioning surfaces and allowable TVU as well as difference statistics. 100% of nodes were within allowable TVU. H13768 - H13769 Junction Comparison file:///H:/OPR-E351-KR-22/Surveys/H13768/01_HDR/Reports/Descriptive_Report/SupportFiles/H13768_H13769_JuncTrac.png H13768 - H13769 Difference Statistics file:///H:/OPR-E351-KR-22/Surveys/H13768/01_HDR/Reports/Descriptive_Report/SupportFiles/H13768_H13769_Junctions_DiffTrac.png Sonar system quality control checks were conducted as detailed in the quality control section of the DAPR. None Exist There were no conditions or deficiencies that affected equipment operational effectiveness. None Exist There were no other factors that affected corrections to soundings. SVP casts were generally taken every 2 hours. Occasionally casts would exceed a 2 hour frequency, however would never exceed a 4 hour frequency. On R/V Endeavor, R/V Pulse, R/V Spectrum, R/V Voxel, and R/V 505 casts were applied in QPS Qinsy acquisition software at the time of the cast. Surface SVP measured at 1Hz was compared to surface speed from the current profile in real-time. If the surface velocity comparison was in excess of 2m/s at any time during survey operations, a new cast was taken. Surface sound speeds were compared in real-time and profile to profile for each cast on the vessel. Additionally, the processor reviewed profiles in Qimera to remove spurious readings within a cast, compare day-to-day casts, and to check distribution over the surveyed area, in order to better understand trends for efficient acquisition planning. All equipment and survey methods were used as detailed in the DAPR. Data Density Evaluation In order to determine if the density of the data met the specified 5 soundings per node, data density was evaluated using DensityTrac in the AmiTrac program, developed in-house by eTrac. Each finalized CUBE weighted dynamic surface's nodes were exported to a BBH file. The BBH file was then loaded into the DensityTrac program and density statistics were computed. For H13768 the following percentages represent the results of the density query: Complete Coverage MBES (Finalized 1m CUBE weighted Dynamic Surface) 98.64% of nodes are composed from at least 5 soundings. H13768 Finalized 1m MBES Density Distribution file:///H:/OPR-E351-KR-22/Surveys/H13768/01_HDR/Reports/Descriptive_Report/SupportFiles/H13768_DensityTrac.png All data reduction procedures conform to those detailed in the DAPR. All sounding systems were calibrated as detailed in the DAPR. Backscatter data were collected throughout the survey and are retained in the raw DB files. Every effort was made in the field to collect quality backscatter data while maintaining the primary mandate of high quality bathymetric data. eTrac verified coverage and general quality of the backscatter data collected daily. A beam intensity window was monitored in Qinsy during acquisition to ensure backscatter data collection. Raw backscatter data were viewed in QPS FMGeocoder (FMGT) to further confirm collection criteria had been met. After MBES data were fully processed and cleaned in Qimera, GSF files were exported and brought into FMGT and processed into backscatter mosaics grouped by acoustic frequency and survey system. NOAA Profile Version 2022 Feature Object Catalog, NOAA Profile Version 2022 was used only in CARIS. Qimera was used as the primary processing software. H13768 _MB_1m_MLLW_Final BAG 1 0.42 29.7 NOAA_1m Complete MBES H13768_MBAB_2m_EN_400kHz_1of5 MB Backscatter Mosaic 2 N/A Complete MBES H13768_MBAB_2m_FF_400kHz_2of5 MB Backscatter Mosaic 2 N/A Complete MBES H13768_MBAB_2m_PU_400kHz_3of5 MB Backscatter Mosaic 2 N/A Complete MBES H13768_MBAB_2m_SP_400kHz_4of5 MB Backscatter Mosaic 2 N/A Complete MBES H13768_MBAB_2m_VO_400kHz_5of5 MB Backscatter Mosaic 2 N/A Complete MBES H13768_SSSAB_1m_400kHz_1of2 SSS Mosaic 1 N/A 100% SSS H13768_SSSAB_1m_400kHz_2of2 SSS Mosaic 1 N/A 200% SSS A 1m surface is provided meeting complete coverage MBES with backscatter specifications for H13768. Note: The 1m MBES surface's depth ranges were extended past 20m to include the remaining deeper values beyond 20m to avoid creating superfluous surfaces at a lower resolution. A 1m mosaic is provided meeting complete coverage with 100% SSS specifications for H13768. A separate 1m mosaic is also provided meeting specifications for the 200% disproval radi. H13768 Finalized 1m CUBE Weighted Dynamic Surface Coverage file:///H:/OPR-E351-KR-22/Surveys/H13768/01_HDR/Reports/Descriptive_Report/SupportFiles/H13768_SurfaceCoverage_MBES_1m.png H13768 Finalized 2m MBAB mosaics file:///H:/OPR-E351-KR-22/Surveys/H13768/01_HDR/Reports/Descriptive_Report/SupportFiles/H13768_MosiacCoverage_MBAB.png H13768 Finalized 1m SSS mosaic file:///H:/OPR-E351-KR-22/Surveys/H13768/01_HDR/Reports/Descriptive_Report/SupportFiles/H13768_SurfaceCoverage_SSSAB_1m.png Additional Task: Final Data Submission - Grids An additional assigned task for this sheet was to include interpolated grids in Mean Lower Low Water (MLLW) and North American Vertical Datum of 1988 (NAVD88) datum. Additional information discussing the vertical or horizontal control for this survey can be found in the accompanying HVCR and DAPR. Mean Lower Low Water ERS via ERTDM OPR-E351-KR-22_NAD83-MLLW.qgfvom In order to reference soundings to Mean Lower Low Water Datum, a separation model was provided by NOAA and was applied to the Qinsy DB files via a .qgfvom separation file in the acquisition software. North American Datum 1983 (2011) Projected UTM 18 RTX Applanix PosPac MMS was utilized to post process real time positioning data utilizing Trimble's PP-RTX implementation of Trimble CenterPoint RTX to create a Smoothed Best Estimate of Trajectory (SBET). GNSS satellite corrections were received on each vessel using either the G2+ or G4+ carrier signal from the Marinestar Global Correction System maintained by Fugro. Additional Task: Final Data Submission- Grids An additional assigned task for this sheet was to include interpolated grids in North American Vertical Datum of 1988 (NAVD88) datum. In order to reference soundings to NAVD88 Datum, a separation model was provided by NOAA and was applied to the gridded MLLW data in QGIS. A chart comparison was conducted for H13768 using Pydro CA tools, Qimera, and Caris HIPS and SIPS. Survey data were compared against the largest scale ENC to accomplish the chart comparison. The largest scale ENC does not cover the entire survey boundary so two other charts were used to complete the chart comparison. Details of the ENCs used are listed below. US5VA51M, scale: 40000, edition: 29, update application date: 06/07/2022, issue date: 06/07/2022 US5VA25M, scale: 40000, edition: 37, update application date: 06/09/2022, issue date: 06/09/2022 US5VA32M, scale: 20000, edition: 36, update application date: 06/13/2022, issue date: 06/13/2022 Throughout survey operations sounding comparisons between the charted depths and the surveyed depths were analyzed to identify depth discrepancies. Using 1 meter CUBE weighted Dynamic surfaces, soundings were generated in the "Sounding Selection" tab of Pydro CA tools. Soundings were displayed against the charted soundings and a visual comparison was made in Caris HIPS and SIPS. Additionally, potential DtoNs and discrepancies were generated using the "DTM vs Chart" tab of Pydro CA tools. The results were displayed through CA tools and investigated in CARIS HIPS and SIPS and Qimera. An overview image of the generated soundings on each chart is included below. Results of the chart comparison are included in the following sections. Generated Soundings used for Chart Comparison (US5VA51M) file:///H:/OPR-E351-KR-22/Surveys/H13768/01_HDR/Reports/Descriptive_Report/SupportFiles/H13768_ChartComparison_US5VA51M.png Generated Soundings used for Chart Comparison (US5VA25M) file:///H:/OPR-E351-KR-22/Surveys/H13768/01_HDR/Reports/Descriptive_Report/SupportFiles/H13768_ChartComparison_US5VA25M.png Generated Soundings used for Chart Comparison (US5VA32M) file:///H:/OPR-E351-KR-22/Surveys/H13768/01_HDR/Reports/Descriptive_Report/SupportFiles/H13768_ChartComparison_US5VA32M.png US5VA51M 20000 61 2022-06-07 2022-06-07 US5VA25M 40000 37 2021-11-30 2022-06-09 US5VA32M 20000 36 2022-06-13 2022-06-13 There were 11 DtoNs found in H13768, and added to the Final Feature File (FFF). Each feature in the FFF has been given a unique identifier in the "userid" field of the .000 S-57 file (format 4XXXXX). Refer to the FFF for determinations and recommendations of each feature. The DtoNs were submitted in the following Danger to navigation reports: H13768_DtoN_01 H13768_DtoN_02 H13768_DtoN_03-11 There were 1063 charted features assigned to H13768 that are included in the Final Feature File (FFF). Each feature in the FFF has been given a unique identifier in the "userid" field of the .000 S-57 file (format 4XXXXX). Refer to the FFF for determinations and recommendations of each feature. 218 new features were found in H13768. Each feature in the FFF has been given a unique identifier in the "userid" field of the .000 S-57 file (format 4XXXX). Refer to the FFF for determinations and recommendations of each feature. Throughout H13768 there were over 500 significant SSS contacts with shadow heights equal to or exceeding 1 meter that were not investigated or included in the FFF as they were believed to be temporary aids for fishing gear. A majority of them were located in clusters in a charted Marine Information Area in proximity to the output of College Creek with a textual description stating “CAUTION - FISH TRAP AREAS AND STRUCTURES: Mariners are warned that numerous uncharted duck blinds and fishing structures, some submerged, may exist in the fish trap areas. Such structures are not charted unless known to be permanent.” They were associated with fishing structures set up perpendicular to shore measuring 300-600 meters in length, often with stakes and buoys visible above water line. In many instances in H13768 field crews witnessed these Fish Trap Areas being tended to by local fishermen, and so were considered to be temporary and not always investigated. In locations where investigations did occur, features associated with significant SSS contacts were often found in only one line of MBES data and/or less than 1 meter in height, and further deemed insignificant and temporary. Upon further discussion with the COR, significant SSS contacts labeled as fishing gear were made into features in the FFF, despite not having been investigated. Standalone stakes were made into point features, while clusters of many stakes seen in both SSS and MBES were included as area features. In areas located outside the primary traffic corridor and areas outside of low under keel clearance, only the most significant contacts within an 8 mm radius referenced to chart scale were made into features. Some stake features identified in H13768 did not have reliable least depth values so a non-standard QUASOU combination of "depth known" has been used to most effectively represent these features. Stakes captured in MBES that were less than 1 meter in height were not included, nor were standalone stakes that were located within charted Fish Trap Areas. Note: DtoNs are not included in the number of new features in this section. DtoNs can be found separately in section D.1.2. H13768 Uncharted Features - Evidence of Fishing in SSS file:///H:/OPR-E351-KR-22/Surveys/H13768/01_HDR/Reports/Descriptive_Report/SupportFiles/H13768_UnchartedFeatures_Fishing_SSS.png H13768 Uncharted Features - Evidence of Fishing in MBES file:///H:/OPR-E351-KR-22/Surveys/H13768/01_HDR/Reports/Descriptive_Report/SupportFiles/H13768_UnchartedFeatures_Fishing_MBES.png Tylers Beach Channel was assigned as a dredged area. No discrepancies were found within our survey extents. The channel was not fully addressed as it was partially inshore of NALL. The dredged area with Feature ID US 0000009038 00001 has a controlling depth of 3.60m. Shoal soundings with a least depth of 2.78m were detected within the dredged area. The dredged area with Feature ID US 0000015021 00001 has a controlling depth of 4.70m. Shoal soundings with a least depth of 3.64m were detected within the dredge area. The dredged area was not fully addressed as it was partially inshore of NALL. The dredged areas were not included in the FFF following investigation requirements. Throughout H13768 there were temporary aids for fishing gear. These aids were not included in the FFF due to their temporary nature. All charted AtoNs within the survey area were found to be on station. No AtoNs were reported to the U.S. Coast Guard. No Maritime Boundary Points were assigned for this survey. 14 bottom samples were obtained in accordance with section 7.1 of the HSSD 2022 in areas designated by the field through discussions with our COR. Detailed information and images of the bottom samples are located in the Final Feature File (FFF). Each bottom sample has been given a unique identifier in the "userid" field of the .000 S-57 file (format DX). There were 8 overhead features assigned to H13768. Assigned overhead features were visually confirmed and no discrepancies were found. The overhead features were not included in the FFF following investigation requirements. There were 3 submarine pipelines assigned to H13768. 1 was not addressed as it was inshore of NALL, and 2 were confirmed in the MBES data and no discrepancies were found. In addition to the assigned pipelines, there were 3 new uncharted exposed pipelines that were deemed non-dangerous and reported to the COR and Bureau of Safety and Environmental Enforcement. Each feature in the FFF has been given a unique identifier in the "userid" field of the .000 S-57 file (format 4XXXXX). Refer to the FFF for determinations and recommendations of each feature. There were 59 offshore platforms assigned to H13768 that are included in the Final Feature File (FFF). In addition to the assigned offshore platforms, there were 5 new platforms that were found using visual observation. Each feature in the FFF has been given a unique identifier in the "userid" field of the .000 S-57 file (format 4XXXXX). Refer to the FFF for determinations and recommendations of each feature. There were 2 Ferry Routes assigned to H13768. The features were visually confirmed and there were no discrepancies found. The features were not included in the FFF following investigation requirements. Circular to oblong shaped mounds with heights up to 3m were identified in H13768. The mounds were found in water depths ranging from 3 to 9 meters, although 4 to 7 meters appeared to be the most common depth. The individual mounds and groupings of mounds tend to be elongated in the direction of current flow with long axis length of individual mounds ranging from a few meters to hundreds of meters. The mounds have a significantly higher acoustic reflectivity than the surrounding riverbed. Riverbed scouring is commonly observed along the margins of mounds. Additionally, abnormally large shifting sand waves were detected. Sand waves were with amplitudes up to 0.6m and wavelengths up to 10m were observed. H13768 Abnormal Seafloor Condition - Mounds file:///H:/OPR-E351-KR-22/Surveys/H13768/01_HDR/Reports/Descriptive_Report/SupportFiles/H13768_Abnormal_Seafloor_Condition_Mounds.png H13768 Abnormal Seafloor Condition - Sand Waves file:///H:/OPR-E351-KR-22/Surveys/H13768/01_HDR/Reports/Descriptive_Report/SupportFiles/H13768_Abnormal_Seafloor_Condition_Sand_Waves.png There were 162 shoreline construction features assigned to H13768 that are in the Final Feature File (FFF). There was 1 new shoreline construction feature added to the FFF. Each feature in the FFF has been given a unique identifier in the "userid" field of the .000 S-57 file (format 4XXXXX). Refer to the FFF for determinations and recommendations of each feature. 5 dredge areas were assigned to H13768. 1 dredge area was fully addressed, 2 were partially addressed due to NALL, and 2 were not addressed as they were inshore of NALL. Some discrepancies with controlling depths were found within our survey extents and are detailed in Section D.1.5. No new surveys or further investigations are recommended for this area. No new ENC scales 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 CUBE surfaces, 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. David Neff Chief of Party 2024-05-14