OPR-K376-KR-18Port Lavaca, TXPort Lavaca, TXTerrasond, Ltd.H13187910 NM WSW of Entrance to Colorado RiverTexasUnited States400002018Andrew OrthmannNavigable Area2018-07-182018-11-282018-12-13Multibeam Echo SounderSide Scan SonarmetersUniversal Transverse Mercator (UTM)UTCAtlantic 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 ##N, <vertical datum>. All references to other horizontal or vertical datums in this report are applicable to the processed hydrographic data provided by the field unit.ContractorThe survey area is located offshore SE Texas, centered on Port Lavaca. Water depths range from approximately 15 to 22 meters. Field work was carried out between November and December, 2018. Final processing and reporting was carried out between January and May, 2019. Eight other nearby sheets were surveyed concurrently. Work was done in accordance with the Hydrographic Survey Instructions (dated July 18th, 2018) and the NOS Hydrographic Surveys Specifications and Deliverables (HSSD), April 2018 edition.28.512558055696.16071528.325262777895.9028188889Graphic showing survey extents.SupportFiles\H13187_Survey_Outline.jpgThe SE portion of the assigned survey area was not surveyed due to reaching the project-wide limit of 7,869 LNM collected.This project is located in the vicinity of Port Lavaca, which includes the Matagorda Bay Shipping Channel. Port Lavaca is a major sea port that allows shipping to support the fishing, manufacturing, agriculture, tourism, as well as the fishing industries in the state of Texas. As a leader in the shrimp processing industry, Port Lavaca allows million tons of seafood to be shipping through its port yearly. Port Lavaca also supports shipping for Matagorda Bay, which houses several large manufacturing plants and a nuclear station. The U.S. Army Corps of Engineers maintains the Matagorda Bay Shipping Channel which is dredged and there are future plans to expand this dredged channel to 44 ft. in depth and 400 ft. wide.4 The survey area covers the approaches to the shipping channel in an effort to cover all shipping traffic into the Matagorda Shipping Channel. Recent hurricane activity in 2017 has made previous bathymetry in the area unreliable. This survey will allow shipping activities to continue into the Port of Lavaca.The entire survey is adequate to supersede previous data.H13180-H13187, except H13181Complete Coverage (Refer to HSSD Section 5.2.2.3)All waters in survey areaLNM no less than 7869 LNM. Report significant shoaling via weekly progress report. COR may adjust survey prioritization based on observed shoaling.Approximately 9,103 LNM were collected project-wide, which exceeds the minimum of 7,869 required in the Project Instructions. The 13.5% overage was largely due to unplanned infill/rerun work in areas of marginal data. Both "Option A: Complete Coverage Multibeam" and "Option B: 100% side scan sonar coverage with concurrent multibeam" were used to meet HSSD Section 5.2.2.3 "Complete Coverage" requirements during this survey. Option B was favored whenever possible and used for most of the area, but Option A was also frequently exercised when the SSS equipment was experiencing issues or SSS data quality had degraded to an unacceptable degree. Infills/reruns on holidays in Option B areas were also frequently MBES-only if MBES was capable of efficiently covering the holiday.Graphic showing survey coverage extents.SupportFiles\H13187_Survey_Coverage.jpgBunny Bordelon08.3000668.7037.8008.3000668.7037.805.51200054.82018-11-282018-11-292018-11-302018-12-012018-12-022018-12-032018-12-122018-12-13Refer 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, and any deviations from the DAPR are discussed in the following sections.Bunny Bordelon45.73.5Bunny BordelonSupportFiles\BunnyBordelon.jpgThe RV Bunny Bordelon is owned and operated by Bordelon Marine Services, LLC of Houma, Louisiana. It was outfit with a 20' conex on the back deck for working space, an A-frame and a winch for towed SSS operations, and a retractable MBES pole mid-ship on its port-side. Note the other vessels detailed in the DAPR were not utilized on this survey sheet.Teledyne RESONSeabat T50 IDHMBESEdgeTech4200SSSApplanixPOS MV 320 v5Positioning and Attitude SystemAML OceanographicMinos-XSound Speed SystemAML OceanographicMicroX SVSSound Speed SystemValeportRapidSVSound Speed SystemValeportSWIFT SVPSound Speed SystemTeledyne OceanscienceRapidCastUnderway Sound Speed Deployment SystemEffort was made to ensure crosslines had good temporal and geographic distribution, were angled to enable nadir-to-nadir as well as nadir-to-outer beam comparisons, and that the required percent of mainscheme LNM was achieved. The crossline analysis was conducted using CARIS HIPS “Line QC Report” process. Each crossline was selected individually and run through the process, which calculated the depth difference between each accepted crossline sounding and a "QC" BASE (CUBE-type, 2 m resolution) surface’s depth layer created from the mainscheme data. QC surfaces were created with the same parameters used for 2 m surfaces as the final surfaces, with the important distinction that the QC surfaces did not include crosslines so as to not bias the results. Differences in depth were grouped by beam number and statistics were computed, including the percentage of soundings with differences from the QC surface falling within IHO Order 1a. When at least 95% of the sounding differences exceed IHO Order 1a, the crossline was considered to “pass,” but when less than 95% of the soundings compare within IHO Order 1, the crossline was considered to “fail.” A 5% (or less) failure rate was considered acceptable since this approach compares soundings to a surface (instead of a surface to a surface), allowing for the possibility that noisy crossline soundings that don't adversely affect the final surface(s) could be counted as a QC failure under this process. Lines used as crosslines and their % of soundings passing IHO Order 1a, sorted from highest passing to lowest, are listed below. 2192-Bunny-347-J2-XL2 -- 100.0% pass 2052-Bunny-346-J-XL_02 -- 100.0% pass 2014-Bunny-346-J1-XL3 -- 100.0% pass 2013-Bunny-346-J1-XL2 -- 100.0% pass 2011-Bunny-346-J1-XL1 -- 100.0% pass 1286-Bunny-337-J2-XL1 -- 100.0% pass 1247-Bunny-335-J1_XL_01 -- 100.0% pass 1175-Bunny-333-J1_alt -- 100.0% pass 1174-Bunny-333-J1_alt -- 100.0% pass 1165-Bunny-333-J1_alt -- 100.0% pass 1164-Bunny-333-J1_alt -- 100.0% pass 1163-Bunny-333-J1_alt -- 99.9% pass Note that individual crosslines often have two or more files (or segments) in CARIS due to the automatic file splitting feature in the acquisition software (QPS QINSy). For each individual crossline, all applicable segments were selected and ran together through the QC report process so that the QC report would reflect the crossline as a whole instead of its individual file segments. Results: Agreement between the mainscheme-only surface and crossline soundings is excellent. Compared to the mainscheme-only surface, 9 of 10 crosslines had 100% of soundings comparing within IHO Order 1a. One crossline had a 99.9% passing rate, which exceeded the 95% threshold for passing QC results. Refer to Separate II: Digital Data for the detailed Crossline QC Reports.0.1040ERS via VDATUMRV Bunny Bordelon020.025The surfaces were finalized in CARIS HIPS so that the uncertainty value for each grid cell is the greater of either standard deviation or uncertainty. The surfaces were then ran through NOAA's QC Tools "QA" utility to compare uncertainty values to allowable TVU by depth. Results: Greater than 99.5% of grid cells for all final surfaces have uncertainty within the allowable TVU. The relatively few grid cells exceeding allowable TVU were found to primarily be on the edges of swaths without overlap, overlap areas exhibiting sound speed refraction error, or over features. The surfaces in these areas were examined and determined to be within specifications. Refer to the DAPR for more information on derivation of the values used for TPU estimates.This survey junctions with one Current surveys. All were surveyed concurrently with this survey. NOAA's "Gridded Surface Comparison V18.4" utility was used to complete the junction comparisons. The utility differences the surfaces of the junctioning surveys and generates statistics, including the percentage of grid cells that compare to within allowable TVU. 1 m-resolution CUBE surfaces were used for all comparisons.Graphic showing junctions with this survey.SupportFiles\H13187_Survey_Junctions.jpgH13182400002019Terrasond, Ltd.NWAgreement is excellent between the two Current surveys. The mean difference is 0.01 m, and greater than 99.5% of grid cells compare to within the allowable TVU.Sonar system quality control checks were conducted as detailed in the quality control section of the DAPR.None ExistThere were no conditions or deficiencies that affected equipment operational effectiveness.Sound Speed ErrorSound speed error or refraction is common in this data set. This is observed as a general downward or upward cupping ("frowning" or "smiling") of the seafloor MBES profiles. The issue was exacerbated by use of a dual-head MBES system, which increased swath-width in order to cover more area per LNM collected but also resulted in outer beam data that was more susceptible to induced error from variations in sound speed profiles. In processing, lines with excessive sound speed error were analyzed to determine if better results could be obtained from manually choosing a specific sound speed profile instead of using the project default "nearest in distance within time 4 hours". These are itemized later in this report. Finally, swath filters as well as manual editing in CARIS subset mode was used to reject outer beam soundings that appeared to exceed allowable TVU (considered to be greater than 0.5 m from estimated true seafloor based on nadir depth). Manual editing often left isolated nodes or speckled edges in the final surfaces. Crossline analysis, which included crossings of good near-nadir crossline data over outerbeam mainscheme data exhibiting sound speed error, passes within IHO Order 1a indicating final surfaces are within specifications.Example of sound speed error from this survey from CARIS subset. Gray soundings were considered to exceed IHO Order 1a and were rejected so as to be excluded from the final surfaces.SupportFiles\SVP_Example.jpgSSS Refraction and Surface NoiseThe SSS image quality is intermittently affected by thermocline refraction as well as water column noise due to waves at the surface, leading to variable artifacts in SSS data. SSS image quality was monitored continually during acquisition and SSS operations were stopped when it was determined that imagery quality had degraded to a point that significant objects were unlikely to be resolved. At this time either MBES-only operations were carried out with a tighter line spacing to obtain Complete Coverage, or vessel downtime due to weather was commenced.2 hoursSound speed profiles ("casts") were collected while underway. A combination of AML Minos-X, Valeport RapidSV, and Valeport SWIFT SVP profilers were used over the course of the project. Changes in sound speed at the MBES sonar head were monitored and a sound speed profile was acquired when the sound speed at the head differed from the sound speed at the depth of the sonar head in the previous profile by greater than 2 m/s. This resulted in an interval of approximately 2 hours between subsequent casts. Casts were taken as deep as possible, usually extending to the seafloor. These were normally applied nearest in distance in time within 4 hours in CARIS HIPS to exclude profiles too outdated or distant from the applicable sounding data. Refer to the DAPR for more information on SVP profiling including specific instruments used, SVP confidence checks performed, and processing methodology.All equipment and survey methods were used as detailed in the DAPR.SVP Profile Exceptions As described earlier, in processing, lines with excessive sound speed error were analyzed to determine if better results could be obtained from manually choosing a specific sound speed profile instead of using the project default "nearest in distance within time 4 hours". To apply in CARIS, this necessitated placing individual casts in their own CARIS SVP file and applying using the custom file instead of the sheet-wide file which contained all casts. These were also required utilizing a custom time allowance instead of the standard 4-hour cast selection criteria. These files are included with the CARIS SVP data and were applied as follows: JD332 Used Line_1152-Bunny-332-J1-224_-_0003_JD332_2312.svp to force the below-named lines to use the JD332 2312 SVP profile. 1152-Bunny-332-J1-224_-_0003 Used Line_1150-Bunny-332-J1-208_-_0002_JD332_1415.svp to force the below-named lines to use the JD332 1415 SVP profile. Line_1150-Bunny-332-J1-208_-_0002 Used Line_1154-Bunny-332-J1-240_-_0002_JD332_2025.svp to force the below-named lines to use the JD332 2025 SVP profile. 1154-Bunny-332-J1-240_-_0002 Used Line_1149-Bunny-332-J1-128_-_0002_JD332_1415.svp to force the below-named lines to use the JD332 14:15 SVP profile. 1149-Bunny-332-J1-128_-_0002 JD335 Used Line_1248-Bunny-335-J2-1_-_0001_JD336_0129.svp to force the below-named lines to use the JD336 01:29 SVP profile. 1248-Bunny-335-J2-1_-_0001 (Nearest in distance within 4 hours) Used Line_1242-Bunny-335-J1-992_-_0002_JD335_1608.svp to force the below-named lines to use the JD335 1608 SVP profile. 1242-Bunny-335-J1-992_-_0002 JD336 Used Bunny_JD336_J2_line.file.numbers_1255.0002_1251.0004__1254.0001_JD336_0609.svp to force the lines named below to use the JD336 06:09 SVP profile. 1251-Bunny-336-J2-17_-_0004 (Nearest in distance within 6 hours) 1254-Bunny-336-J2-97_-_0001 (Nearest in distance within 4 hours) 1255-Bunny-336-J2-49_-_0002 (Nearest in distance within 4 hours) 1252-Bunny-336-J2-81_-_0001 (Nearest in distance) 1255-Bunny-336-J2-49_-_0003 (Nearest in distance) 1255-Bunny-336-J2-49_-_0004 (Nearest in distance) 1253-Bunny-336-J2-33_-_0003 (Nearest in distance) 1249-Bunny-336-J2-1_-_0001 (Nearest in distance) Used Line_1250-Bunny-336-J2-65_-_0001_JD336_0257_0609.svp to force the named line to use JD336 0257 or 0609 SVP. 1250-Bunny-336-J2-65_-_0001 (Nearest in distance) Used Line_1253-Bunny-336-J2-33_-_0001_JD336_0257.svp to force the named line to use JD336 0257 SVP. 1253-Bunny-336-J2-33_-_0001 (Nearest in time) Used Line_1273-Bunny-336-J2-113_-_0002_JD337_0122.svp to force the named line to use JD337 0122 SVP. 1273-Bunny-336-J2-113_-_0002 (Nearest in distance within 6 hours) 1273-Bunny-336-J2-113_-_0001 (Nearest in distance) 1264-Bunny-336-J2-129_-_0004 (Nearest in distance) Used Line_1254-Bunny-336-J2-97_-_0004_JD336_0257.svp to force the named line to use JD336 0257 SVP. 1254-Bunny-336-J2-97_-_0004_JD336_0257 1254-Bunny-336-J2-97_-_0003 (Nearest in distance within 4 hours) 1252-Bunny-336-J2-81_-_0004 (Nearest in distance) Used Line_1254-Bunny-336-J2-97_-_0002_JD336_0609.svp to force the named line to use JD336 0609 SVP. 1254-Bunny-336-J2-97_-_0002 Used Line_1256-Bunny-336-J2-145_-_0003_JD336_0801.svp to force the named line to use JD336 0801 SVP. 1256-Bunny-336-J2-145_-_0003 (Nearest in distance) 1258-Bunny-336-J2-177_-_0003 (Nearest in distance) 1258-Bunny-336-J2-177_-_0002 (Nearest in distance) 1258-Bunny-336-J2-177_-_0001 (Nearest in distance) Used Line_1260.0004_1262.0003_JD336_1305.svp to force the named line to use JD336 1305 SVP. 1260-Bunny-336-J2-193_-_0004 (Nearest in distance) 1262-Bunny-336-J2-209_-_0003 (Nearest in distance) 1260-Bunny-336-J2-193_-_0003 (Nearest in distance) 1262-Bunny-336-J2-209_-_0002 (Nearest in distance) Used Line_1263-Bunny-336-J2-161_-_0003_JD336_1525.svp to force the named line to use JD336 1525 SVP. 1263-Bunny-336-J2-161_-_0003 Use Nearest Time for SVP correction lines: 1253-Bunny-336-J2-33_-_0002 1252-Bunny-336-J2-81_-_0003 1252-Bunny-336-J2-81_-_0002 2055-Bunny-346-SheetJ-Infill-11_-_0001 2193-Bunny-347-SheetJ-Infill-11_-_0001All sounding systems were calibrated as detailed in the DAPR.All equipment and survey methods were used as detailed in the DAPR.NOAA Profile V_5_7NOAA Extended Attribute File V5.7 was used as the most current feature file version at the commencement of survey acquisition.H13187_MB_1m_MLLW_FinalCARIS Raster Surface (CUBE)1020NOAA_1mComplete MBESH13187_MB_2m_MLLW_FinalCARIS Raster Surface (CUBE)21840NOAA_2mComplete MBESH13187_SSSAB_1m_400kHzSSS Mosaic1040N/A100% SSSThe final depth information for this survey was submitted as CARIS BASE surfaces (CSAR format) which best represented the seafloor at the time of the survey. The surfaces were created from fully processed data with all final corrections applied. Surfaces were created using NOAA CUBE parameters and resolutions by depth range in conformance with the 2018 HSSD. Surfaces were finalized, and designated soundings were applied. Horizontal projection was selected as UTM Zone 14 North, NAD83. Non-finalized versions of the CSAR surfaces are also included which do not have a depth cutoff applied. These do not have the "_Final" designation in the filename. A crossline QC surface is also included with the surface deliverables ("H13187_XLQC-MS-only_2m"). This is the 2 m resolution CUBE surface in CSAR format discussed previously in the crossline section used to create the crossline QC reports. This surface excludes crosslines. It is included for reference only and should not be used for charting. SSS mosaics were exported from Chesapeake SonarWiz 7 software at 1 m resolution using a grayscale pallet per the 2018 HSSD. The grayscale coverages are not the SonarWiz default color pallet, which is a bronze color -- as a result the grayscale images appear rougher and less visually appealing than the bronze images. Therefore, bronze color versions are also included for reference and are recommended for use over the grayscale versions. An S-57 (.000) Final Feature File (FFF) was submitted with the survey deliverables as well. The FFF contains meta-data and other data not readily represented by the final surfaces, including bottom samples and feature investigation results. An S-57 SSS contact file is also included. Each object is encoded with mandatory S-57 attributes and NOAA Extended Attributes (V#5.7).Additional information discussing the vertical or horizontal control for this survey can be found in the accompanying HVCR.Mean Lower Low WaterERS via VDATUMVDATUM_Outline_Shape_xyNAD83-MLLW_geoid12b.csarReduction to MLLW was accomplished using ERS methodology via VDATUM. The VDATUM model was provided by NOAA prior to operations and had an uncertainty specified as 10.4 cm. The VDATUM model was validated during this survey using comparisons with NWLON gauge data and found to be acceptable for tidal reduction. See the HVCR for validation reports.North American Datum 1983Projected UTM 14Smart BaseApplanix Smart Base (ASB) was used as a comparison against Trimble PP-RTX results, and generally compared to 0.10 m or better.All positions were post-processed in Applanix POSPac MMS software using Trimble PP-RTX as the correction source. RMS errors were generally at 0.10 m or better, both horizontally and vertically.WAAS was used for real-time positioning only, and was replaced in post-processing with PP-RTX solutions for final MBES data. However SSS positions were not post-processed and are therefore based on WAAS positioning.The chart comparison was performed by examining the best-scale Electronic Navigational Charts (ENCs) that intersect the survey area. The latest edition(s) available at the time of the review were used. The chart comparison was accomplished by overlaying the finalized BASE surfaces with shoal-biased soundings, and final feature file on the charts in CARIS HIPS. The general agreement between charted soundings and survey soundings was then examined and a more detailed comparison was undertaken for any shoals or other dangerous features. In areas where a large scale chart overlapped with a small scale chart, only the larger scale chart was examined. USCG LNM and NMs applicable to the survey area issued subsequent to the start of operations and prior to completion of operations were also examined. This consisted of LNM/NMs 48/18 through 51/18. None were found that were applicable to this survey. When comparing to survey data, chart scale was taken into account so that 1 mm at chart scale was considered to be the valid radius for charted soundings and features. It is recommended that in all cases of disagreement this survey should supersede charted data. Results are shown in the following sections. US5TX32M50000302018-07-132019-03-11falseThere is very little overlap between this chart and survey H13187. No charted soundings intersect the survey extents. However, the nearest charted soundings to the overlap area agree to this survey to within 0.5 m or better. US4TX31M80000262019-03-112019-03-19falseGeneral sounding agreement is excellent, with most soundings agreeing to 0.5 m or better. No trends in deepening or shoaling were observed.Soundings from this survey (blue) overlaid on soundings from US4TX31M. SW part of survey area. Soundings in meters.SupportFiles\US4TX31M_SW.jpgSoundings from this survey (blue) overlaid on soundings from US4TX31M. NE part of survey area. Soundings in meters.SupportFiles\US4TX31M_NE.jpgNo Maritime Boundary Points were assigned for this survey.No charted features exist for this survey.No uncharted features exist for this survey that are not discussed elsewhere in this report.Shoal and hazardous features in this area consisted primarily of offshore platforms, discussed in later in this report. Two DTONs were submitted for this survey -- on an uncharted platform and an obstruction: 1. An uncharted platform was found at 28-24-39.1896 N, 96-02-51.76464 W. A photo was taken. Position was derived from MBES soundings on the feature. 2. An obstruction, likely a wellhead, was found at 28-25-19.61184 N, 96-02-21.54804W. The obstruction was picked up in two overlapping MBES lines as well as a 100% SSS pass. Refer to the FFF for details. DTON submission correspondence is included with the deliverables. Note that DTONs were submitted shortly before submittal of this survey and therefore DTON confirmations / DREG registration emails were not available at the time of compilation of this report.No channels exist for this survey. There are no designated anchorages, precautionary areas, safety fairways, traffic separation schemes, pilot boarding areas, or channel and range lines within the survey limits.12 samples were assigned in the project PRF. Samples were successfully obtained at all locations. Photographs were taken but samples were discarded. Bottom sample results are provided in the accompanying FFF.Shoreline was not assigned in the Hydrographic Survey Project Instructions or Statement of Work.No prior survey comparisons were required for this survey.No Aids to navigation (ATONs) exist for this survey.No overhead features exist for this survey.Charted pipelines exist in the area but were not readily discernible in the survey data. None were found to be elevated or of navigational concern. All are recommended for retention in the FFF.Charted platforms were assigned in the CSF and investigated. Most were found to exist but were commonly 20 to 70 m from the charted/assigned position. Confirmed platforms were photographed when possible, and final positions were derived from the MBES sounding data acquired on their support structure. Platforms not observed were disproved with Complete MBES coverage. An uncharted platform and uncharted wellhead were found and submitted as DTONs, as described earlier in this report. Investigation results are available in the accompanying FFF.No ferry routes or terminals exist for this survey.No abnormal seafloor and/or environmental conditions exist for this survey.No present or planned construction or dredging exist within the survey limits.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 Specifications and Deliverables document as well as the Hydrographic Survey Project Instructions and Statement of Work. This data is adequate to supersede charted data in their common areas. This survey is complete and no additional work is required with the exception of deficiencies--if any--noted in the Descriptive Report.Andrew Orthmann, C.H.TerraSond Charting Program Manager2019-05-03Coast Pilot Report2019-04-25VDatum Validation Report for Port Lavaca2019-04-24NCEI Sound Speed Data Submission2019-04-09Marine Mammal Observers Training Logsheet and Observation Logs2019-03-22Port Lavaca Boat Float Tide Analysis2018-09-18