OPR-E351-KR-22 Southwest Chesapeake Bay Rivers Southwest Chesapeake Bay eTrac H13773 9 Option 2 Sheet Eastern York River Virginia United States 10000 2023 David Neff, C.H. Basic Hydrographic Survey 2023-03-08 2023-05-28 2023-12-14 Multibeam Echo Sounder, Side Scan Sonar 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. H13773 covers approximately 18.7 square nautical miles of the Eastern York River, 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 York River, Virginia. H13773 covers approximately 18.7 square nautical miles of survey area. 650.49 linear nautical miles were acquired during the survey. Survey was conducted within these limits between May 28, 2023 (DN148) and December 14, 2023 (DN348). 37.53762222222222 76.81010277777777 37.21535277777778 76.3674361111111 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/H13773/01_HDR/Reports/Descriptive_Report/SupportFiles/H13773_SurveyLimits_Overview.jpg Survey Limits (black line) file:///H:/OPR-E351-KR-22/Surveys/H13773/01_HDR/Reports/Descriptive_Report/SupportFiles/H13773_SurveyLimits.jpg 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 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 H13773 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 8m 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 descrete 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. 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. Additionally, gaps in complete survey coverage exists due to the inability to access restricted naval areas. An example of a coverage gap due to inaccessible restricted areas is presented below. Survey Coverage with combined MBES and SSS file:///H:/OPR-E351-KR-22/Surveys/H13773/01_HDR/Reports/Descriptive_Report/SupportFiles/H13773_SurveyCoverage_MBES_SSS.png Survey Coverage Gap adjacent to Naval Weapons Station Yorktown Ammo Pier due to restricted access file:///H:/OPR-E351-KR-22/Surveys/H13773/01_HDR/Reports/Descriptive_Report/SupportFiles/H13773_CoverageGap_RestrictedAccess.jpg R/V Pulse 0.0 0.0 0.0 0.0 0.0 79.36 0.0 0.0 0.0 R/V Spectrum 0.0 0.0 0.0 0.0 0.0 99.48 0.0 0.0 0.0 R/V 505 0.0 0.0 0.0 0.0 0.0 446.44 0.0 25.2 0.0 0.0 0.0 0.0 0.0 0.0 625.29 0.0 25.2 0.0 4.03 8 0 0 0 18.71 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 2023-06-12 2023-06-16 2023-06-17 2023-06-18 2023-06-19 2023-06-20 2023-06-22 2023-06-23 2023-08-17 2023-08-26 2023-08-27 2023-08-28 2023-08-29 2023-08-30 2023-09-05 2023-09-07 2023-09-19 2023-12-14 This section in XmlDR is titled A.5 but it gets printed in the DR PDF as A.6 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 Pulse 7.3 0.6 R/V Spectrum 6.7 0.6 R/V 505 10.0 0.6 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 505 is a 10 meter aluminum catamaran equipped with a Universal Sonar Mount (USM) starboard multibeam pole mount and davit. Sound Speed System AML Oceanographic MicroX SV Sound Speed System AML Oceanographic BaseX2 Positioning and Attitude System Applanix POS MV 320 v5 SSS EdgeTech 4125 MBES R2Sonic 2022 MBES R2Sonic 2024 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 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 mainscheme miles was 4.03% 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. H13773 Crossline Comparison file:///H:/OPR-E351-KR-22/Surveys/H13773/01_HDR/Reports/Descriptive_Report/SupportFiles/H13773_CrossCheck.png ERS via ERTDM 0.06 R/V 505 0.05 0.2 R/V Pulse 0.05 0.2 R/V Spectrum 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 begining in 2.5.1 and beyond, the user has the ability to export the Dynamic Surface to a Bathymetric Attributed Grid (BAG) with the TVU 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. The TVU was also reviewed using the Colormap Range in the Qimera TVU surface layer. Complete Coverage Option B MBES (Finalized 1m CUBE weighted Dynamic Surface in NOAA QC Tools) = 100% of nodes are within the allowable TVU. H13773 Finalized 1m MBES TVU Statistics file:///H:/OPR-E351-KR-22/Surveys/H13773/01_HDR/Reports/Descriptive_Report/SupportFiles/H13773_MB_1m_MLLW_Final.QAv6.tvu_qc.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. H11295 10000 2007 RU W The junction comparison was performed using all overlapping data between H13773 and H11295. Below is a histogram of junction comparison statistics showing the difference between the junctioning surfaces and allowable TVU as well as difference statistics. 91.39% of nodes were within allowable TVU. Note: Spikes above the allowable TVU were caused by shifting bedforms and scouring near Naval Weapons Station Yorktown Ammo Pier. H13773 - H11295 Junction Comparison file:///H:/OPR-E351-KR-22/Surveys/H13773/01_HDR/Reports/Descriptive_Report/SupportFiles/H13773_H11295_JuncTrac.png H13773 - H11295 Difference Statistics file:///H:/OPR-E351-KR-22/Surveys/H13773/01_HDR/Reports/Descriptive_Report/SupportFiles/H13773_H11295_DiffTrac.png H13773 - H11295 Difference Surface file:///H:/OPR-E351-KR-22/Surveys/H13773/01_HDR/Reports/Descriptive_Report/SupportFiles/H13773_H11295_Junction_Difference.png H13772 10000 2023 eTrac NW The junction comparison was performed using all overlapping data between H13773 and H13772. Below is a histogram of junction comparison statistics showing the difference between the junctioning surfaces and allowable TVU as well as difference statistics. 99.9695% of nodes were within allowable TVU. Note: Spikes above allowable TVU were caused by overlapping data on features where there is slight variation in the coordinates of each surface's node for the least depth of the feature. H13773 - H13772 Junction Comparison file:///H:/OPR-E351-KR-22/Surveys/H13773/01_HDR/Reports/Descriptive_Report/SupportFiles/H13772_H13773_JunctionTrac_Plot.png H13773 - H13772 Difference Statistics file:///H:/OPR-E351-KR-22/Surveys/H13773/01_HDR/Reports/Descriptive_Report/SupportFiles/H13772_H13773_Junctions_DiffTrac.png H13306 20000 2020 Leidos E The junction comparison was performed using all overlapping data between H13773 and H13306. Below is a histogram of junction comparison statistics showing the difference between the junctioning surfaces and allowable TVU as well as difference statistics. 99.88% of nodes were within allowable TVU. Note: Spikes above the allowable TVU were caused by shifting bedforms and seafloor debris. H13773 - H13306 Junction Comparison file:///H:/OPR-E351-KR-22/Surveys/H13773/01_HDR/Reports/Descriptive_Report/SupportFiles/H13773_H13306_JuncTrac.png H13773 - H13306 Difference Statistics file:///H:/OPR-E351-KR-22/Surveys/H13773/01_HDR/Reports/Descriptive_Report/SupportFiles/H13773_H13306_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. SV Casts were applied in QPS Qinsy acquisition software at the time of the survey on R/V Pulse, R/V Spectrum, and R/V 505. 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 H13773 the following percentages represent the results of the density query: Complete Coverage MBES (Finalized 1m CUBE weighted Dynamic Surface) = 98.532% of nodes are composed from at least 5 soundings. H13773 Finalized 1m Complete Coverage MBES Density Distribution file:///H:/OPR-E351-KR-22/Surveys/H13773/01_HDR/Reports/Descriptive_Report/SupportFiles/H13773_MB_1m_MLLW_Final_Density.jpg 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 was 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. H13773_MB_1m_MLLW_Final.BAG BAG 1 0.539 18.118 NOAA_1m Complete MBES H13773_MBAB_2m_SP_400khz_1of3.tif MB Backscatter Mosaic 2 N/A Complete MBES H13773_MBAB_2m_PU_400khz_2of3.tif MB Backscatter Mosaic 2 N/A Complete MBES H13773_MBAB_2m_FF_400khz_3of3.tif MB Backscatter Mosaic 2 N/A Complete MBES H13773_SSSAB_1m_400khz_1of2.tif SSS Mosaic 1 N/A 100% SSS H13773_SSSAB_1m_400khz_2of2.tif SSS Mosaic 1 N/A 200% SSS A 1m surface is provided meeting the set line spacing coverage MBES with backscatter and SSS specifications for 100% coverage for sheet H13773. A 1m mosaic is provided meeting complete coverage with 100% SSS specifications for H13773. A separate 1m mosaic is also provided meeting specification for the 200% disproval radii. H13773 Finalized 1m CUBE Weighted Dynamic Surface Coverage file:///H:/OPR-E351-KR-22/Surveys/H13773/01_HDR/Reports/Descriptive_Report/SupportFiles/H13773_SurfaceCoverage_MBES_1m.png H13773 Finalized 2m MBAB mosaics file:///H:/OPR-E351-KR-22/Surveys/H13773/01_HDR/Reports/Descriptive_Report/SupportFiles/H13773_MosaicCoverage_MBAB.png H13773 Finalized 1m SSS mosaics file:///H:/OPR-E351-KR-22/Surveys/H13773/01_HDR/Reports/Descriptive_Report/SupportFiles/H13773_MosaicCoverage_SSS.jpg 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 VDATUM 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 the G2+ and 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 H13773 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. US5VA60M, scale: 40000, edition: 22, update application date: 11/08/2021, issue date: 09/27/2022 US5VA61M, scale: 40000, edition: 8, update application date: 08/22/2022, issue date: 08/22/2022 US5VA62M, scale: 40000, edition: 8, update application date: 11/1/2017, issue date: 11/1/2017 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 (US5VA60M) file:///H:/OPR-E351-KR-22/Surveys/H13773/01_HDR/Reports/Descriptive_Report/SupportFiles/H13773_ChartComparison_US5VA60M.jpg Generated Soundings used for Chart Comparison (US5VA61M) file:///H:/OPR-E351-KR-22/Surveys/H13773/01_HDR/Reports/Descriptive_Report/SupportFiles/H13773_ChartComparison_US5VA61M.jpg Generated Soundings used for Chart Comparison (US5VA62M) file:///H:/OPR-E351-KR-22/Surveys/H13773/01_HDR/Reports/Descriptive_Report/SupportFiles/H13773_ChartComparison_US5VA62M.jpg US5VA60M 40000 22 2021-11-08 2022-09-27 US5VA61M 40000 8 2022-08-22 2022-08-22 US5VA62M 40000 8 2017-11-01 2017-11-01 There were 12 DtoNs found in H13773, 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 9XXXXX). Refer to the FFF for determinations and recommendations of each feature. The DtoNs were submitted in the following Danger to navigation reports: H13773_DTON_01-07.000 H13773_DTON_08-12.000 There were 261 charted features assigned to H13773, and 2 unassigned charted features 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 9XXXXX). Refer to the FFF for determinations and recommendations of each feature. 56 new features were found in H13773. Each feature in the FFF has been given a unique identifier in the "userid" field of the S-57 file (format 9XXXXX). Refer to the FFF for determinations and recommendations of each feature. Note: DtoNs are not included in the number of new features in this section. DtoNs can be found separately in section D.1.2. The West Point Bar Channel and the York River Channel were assigned as dredged areas in H13773. No discrepancies were found within survey extents. The dredged areas were not included in the FFF following investigation requirements. Throughout H13773 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. 8 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 IX). There were 6 overhead features assigned to H13773. 3 overhead features were visually confirmed with no discrepancies found, and 3 overhead features were not addressed as they were inshore of NALL. The overhead features were not included in the FFF following investigation requirements. There were 3 submarine features assigned to H13773 that were 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 9XXXXX). Refer to the FFF for determinations and recommendations of each feature. There were 6 platforms assigned to H13773 that are included in the Final Feature File (FFF). These were not addressed as they were inshore of NALL. Each feature in the FFF has been given a unique identifier in the "userid" field of the .000 S-57 file (format 9XXXXX). Refer to the FFF for determinations and recommendations of each feature. No ferry routes or terminals exist for this survey. Hundreds of circular and oblong mounds with heights up to 4m were observed in H13773. There were several clusters of mounds along the NALL on the outer edges of the York River Channel. The individual mounds and groupings of mounds tend to be elongate in the direction of current flow with long axis length of individual mounds ranging from a few meters to tens of meters. The mounds have a significantly higher acoustic reflectivity than the surrounding riverbed. Riverbed scouring is commonly observed along the margins of mounds. Abnormal Seafloor Condition - Mounds file:///H:/OPR-E351-KR-22/Surveys/H13773/01_HDR/Reports/Descriptive_Report/SupportFiles/H13773_AbnormalSeafloor_Mounds_MBES_SSS.jpg There were 67 shoreline construction features assigned to H13773 and 2 unassigned charted shoreline construction features 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 9XXXXX). Refer to the FFF for determinations and recommendations of each feature. There were 4 Dredge areas assigned in sheet H13773 that include two sections of the West Point Bar Channel and the York River Channel. There were no discrepancies found against the controlling depths of these channels. The fourth dredge area is alongside the Yorktown Naval Weapons Station Cheatham Annex Pier, which has a controlling depth of 6.5m. Shoal soundings with a least depth of 5m were detected within the dredge area. Dredging along the Yorktown Naval Weapons Station Cheatham Annex Pier file:///H:/OPR-E351-KR-22/Surveys/H13773/01_HDR/Reports/Descriptive_Report/SupportFiles/H13773_DredgeArea_MBES_SSS.jpg No new surveys or further investigations are recommended for this area. No new ENC scales 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 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, CH Chief of Party 2024-03-06