OPR-K379-KR-15 Approaches to Atchafalaya Bay, LA Approaches to Atchafalaya Bay, LA C&C Technologies, An Oceaneering International Company H12790 4 20 NM SSW fo Point Au Fer Louisiana USA 40000 2015 Tara Levy Navigable Area 2015-10-11 2015-10-11 2016-02-18 meters Universal Transverse Mercator UTC Atlantic Hydrographic Branch Contractor The survey area is located 20 NM SSW of Point Au Fer off the coast of Louisiana, USA. 29.098 91.598 28.002 91.497 Survey limits were designed as outlined in the Project Instructions and the HSSD. The purpose of this survey is to provide a contemporary survey to update National Ocean Service (NOS) nautical charting products. Survey H12790 covers 24.29 square nautical miles (SNM) near the Atchafalaya River. The river is the only expanding river delta in North America and the Port of Morgan City has been working to deepen and maintain the channel. The project area potentially covers altered area where depth contours may have migrated. The entire survey is adequate to supersede previous data. Survey coverage for H12790 (Figure 1) was collected in accordance with the requirements outlined in the Project Instructions and HSSD (2015). 100% side scan sonar (SSS) coverage was acquired with concurrent multibeam echosounder (MBES) data. A combination of complete MBES with backscatter and/or water column data and/or SSS data was collected for feature investigations. Figure 1. H12790 Survey Coverage SupportFiles\Fig1_H90_SurveyOutline.tif JQN00023E707 0 0 0 0 0 0 0 0 0 1237094 0 0 0 0 46.57 594.29 0 0 0 0 0 0 0 46.57 594.29 0 0 0 7.84 5 0 0 32 0 24.29 2015-10-11 2015-10-12 2015-10-13 2015-10-16 2015-10-30 2015-11-03 2015-11-04 2015-11-05 2015-11-06 2015-11-07 2015-11-10 2015-11-19 2015-11-20 2015-11-21 2015-11-30 2015-12-01 2015-12-02 2015-12-07 2015-12-08 2016-01-25 2016-02-15 2016-02-18 Refer to the OPR-K379-KR-15 Data Acquisition and Processing Report (DAPR) for additional information regarding survey systems as well as operational, processing and quality control procedures. A summary of the equipment and vessels used for this survey is provided below. JQN00023E707 9.14 0.76 1237094 40.84 1.98 The following vessels were used for data acquisition during this survey: Kongsberg EM2040C MBES Kongsberg EM3002 MBES Klein 5000 V2 SSS Edgetech 4200 P SSS Coda Octopus F180 Attitude and PositioningSystem C-Nav 3050 Positioning System AML SV•Xchange Sound Speed System YSI Electronics 600R-BCR-C-T Sound Speed System Sea-Bird Electronics, Inc. SBE 19 and SBE 19 Plus Sound Speed System The following major systems were used for data acquisition during this survey: Crosslines were run perpendicular to mainscheme lines so that quality control statistics could be performed on the data after completion of mainscheme survey lines. The total crossline miles were 46.57 NM and the total mainline miles were 591.29 NM; investigation lines were not included in mainline totals. The crosslines comprise 7.9 percent of the total mainline miles. Mainlines were compared to crosslines for which there was overlapping data using C & C’s proprietary Hydromap software. The graphs generated from the comparison show the mean difference, RMS difference and confidence interval for each beam. Refer to the DAPR for additional information and Separates II Digital Data for sample graphical documentation. The surface difference tool in CARIS HIPS was used to evaluate crossline and mainscheme line agreement; investigations were not included in the comparisons. The mainline BASE surface was used as Surface 1 and the crossline BASE surface as Surface 2. Statistical information about the difference surface was generated using the compute statistics tool (Figure 2). The analysis shows that greater than 99% of depth difference values are between -0.362 and 0.238 m. This is well within the maximum allowable TVU for the depths of the comparison area (7.52 – 11.64 m) which ranges from ±0.510 to ±0.522 m. All depth difference values between -0.751 m and -0.50 m are associated with a depression feature that is located at 29.074 N, 91.562 W; refer to section D.2.7 for additional information. Statistical crossline information was also generated by comparing each of the crosslines to the depth layer of the 1-m BASE surface of the mainscheme survey lines using the CARIS QC report utility. In general, greater than 99% of crossline soundings fall within the selected Order 1a survey order, as outlined in the CARIS User Manual. Crossline comparisons generated with the CARIS QC report utility as well as the difference BASE surface are shown in the Separates II Digital Data\Checkpoint Summary & Crossline Comparisons folder. Figure 2. Crossline comparison statistical information and histogram output from CARIS compute statistics tool. SupportFiles\Fig2_H90_CrosslineComparison.jpg Figure 3. H12790 Junctions. SupportFiles\Fig3_H90_Junctions.jpg H12788 40000 2015 NOAA Time Charter N H12788 The areas of overlap between Sheets (Figure 3) were evaluated using the CARIS Difference Tool to ensure general agreement of depths. Junction analyses were conducted using 1, 2, or 5 meter BASE surfaces and/or .bag files of all the Sheets. If necessary, data was further reviewed in Subset Editor. The southern margin of survey H12788 borders the northern margin of survey H12790. 1 meter BASE surfaces were used for comparison purposes. Figure 4 shows statistical information for the junction generated with the CARIS compute statistics tool. Depths from survey H12790 agree well with depths from survey H12788 with 100% of depth difference values between -0.281 and 0.234 m. Figure 4. Statistical information and histogram output from CARIS Compute Statistics tool for the difference surface generated between H12790 and H12788 1-meter surfaces. SupportFiles\Fig4_H90_Junction_H12788.jpg H12789 40000 2015 C&C Technologies, An Oceaneering International Company W H12789 The western margin of survey H12789 borders the eastern margin of survey H12790. 1 meter BASE surfaces were used for comparison purposes. Figure 5 shows statistical information for the junction generated with the CARIS compute statistics tool. Depths between the two surveys agree well with 99% of depth difference values between -0.26 and 0.24 m. Note that this comparison is preliminary and the final comparison will be found in the H12789 Descriptive Report. Figure 5. Statistical information and histogram output from CARIS Compute Statistics tool for the difference surface generated between H12790 and H12789 1-meter surfaces. SupportFile\Fig5_H90_Junction_H12789.jpg H11288 20000 2005 NOAA Time Charter SE H11288 The southeastern margin of survey H12188 borders the northwestern margin of survey H12790. The H11288_2m_MLLW_3of8 and H11288_2m_MLLW_4of8 .bag files were combined using CARIS HIPS for this analysis and compared to a 2 meter surface of H12790. Figure 6 shows statistical information for the junction generated with the CARIS compute statistics tool. The difference values demonstrate that in general, the depths from survey H12790 are deeper than those of survey H11288, with nearly 96% of the depth differences between -0.011 and 0.589 m. Figure 6. Statistical information and histogram output from CARIS Compute Statistics tool for the difference surface generated between H12790 and H11288 2-meter surfaces. SupportFiles\Fig6_H90_Junction_H11288-2m.jpg H11288 20000 2005 NOAA Time Charter SE H11288 The southeastern margin of survey H12188 borders the northwestern margin of survey H12790. The H11288_5m_MLLW_7of8 and H11288_5m_MLLW_8of8 .bag files were combined using CARIS HIPS for this analysis and compared to a 5 meter surface of H12790. Figure 7 shows statistical information for the junction generated with the CARIS compute statistics tool. The difference values demonstrate that in general, the depths from survey H12790 are deeper than those from survey H11288, with 94% of the depth differences between 0.067and 0.567 m. Figure 7. Statistical information and histogram output from CARIS Compute Statistics tool for the difference surface generated between H12790 and H11288 5-meter surfaces. SupportFiles\Fig7_H90_Junction_H11288-5m.jpg H11475 20000 2005 NOAA Time Charter NE H11475 The northeast margin of survey H11475 borders the southwestern margin of survey H12790. An error occurred when attempting to combine the H11475 .bag surfaces that overlap H12790. The combine surface tool introduced an erroneous data point at 29-00-56.302N, 091-34-04.188W which shows a negative depth instead of a positive depth and therefore showed an erroneous depth difference value. For this reason, the H12790 2 meter surface was compared to the overlapping H11475 .bag surfaces (H11475_2m_MLLW_10of16, H11475_2m_MLLW_11of16, and H11475_2m_MLLW_12of16) separately. Figures 8 - 10 shows statistical information for the junctions generated with the CARIS compute statistics tool. The depth difference values demonstrate that the depths from survey H12790 are generally deeper than the depths from survey H11475. Figure 8. Statistical information and histogram output from CARIS Compute Statistics tool for the difference surface generated between H11475 (Bag 10of16) and H12790 2-meter surfaces. SupportFiles\Fig8_H90_Junction_H11475_10of16.jpg Figure 9. Statistical information and histogram output from CARIS Compute Statistics tool for the difference surface generated between H11475 (Bag 11of16) and H12790 2-meter surfaces. Fig9_H90_Junction_H11475_11of16.jpg Figure 10. Statistical information and histogram output from CARIS Compute Statistics tool for the difference surface generated between H11475 (Bag 12of16) and H12790 2-meter surfaces. Fig10_H90_Junction_H11475_12of16.jpg H12557 40000 2013 C&C Technologies, an Oceaneering International Company N H12557 The northern margin of survey H12557 borders the southern margin of survey H12790. 1 meter BASE surfaces were used for comparison purposes. Figure 11 shows statistical information for the junction generated with the CARIS compute statistics tool. The difference values demonstrate that the depths from H12790 are generally deeper than the depths from H12557, with over 99% of the depth differences between -0.280 and 0.418 m. Figure 11. Statistical information and histogram output from CARIS Compute Statistics tool for the difference surface generated between H12557 and H12790 1-meter surfaces. SupportFiles\Fig11_H90_Junction_H12557.jpg H12556 40000 2013 C&C Technologies, an Oceaneering International Company NW H12556 The northwestern margin of survey H12556 borders the southeastern margin of survey H12790. 1 meter BASE surfaces were used for comparison purposes. Figure 12 shows statistical information for the junction generated with the CARIS compute statistics tool. The difference values demonstrate that the depths from H12556 are generally deeper than the depths from H12790, with over 98% of the depth differences between -0.352 and -0.052m. However, there is very little overlap between the two surveys, so refer to the H12789 Descriptive Report for a more reliable comparison. Figure 12. Statistical information and histogram output from CARIS Compute Statistics tool for the difference surface generated between H12556 and H12790 1-meter surfaces. SupportFiles\Fig12_H90_Junction_H12556.jpg Odom single beam echosounders were continuously operated and monitored during the survey as an independent check on the multibeam bottom-detect. The R/V Sea Scout (Hull ID 1237094) is equipped with an Echotrac MK III, and the R/V C-Ghost (Hull ID JQN00023E707) is equipped with an ODOM Hydrotrac. Equipment Effectiveness If necessary, the angle of the multibeam sonars were modified in order to moderate the effects of factors such as increased sea state or to increase coverage; any changes are documented in the acquisition logs. Operation of the SSS at 50 m range with an 80 meter line spacing ensured 100% SSS coverage. When environmental factors limited the effective range of the side scan sonar, split lines were collected to ensure complete coverage. Factors Affecting Soundings Weather, sea state, water column sound speed, thermoclines, and fish/marine life were all temporary factors that affected the data periodically throughout the duration of the survey; these are noted in the acquisition and processing logs Two times daily. Sea Bird Electronics SBE19 and SBE19plus CTDs were used for speed of sound measurements in the water column. Casts were conducted at least twice daily on board the R/V Sea Scout, at least once daily on board the R/V C-Ghost and more often as needed. The multibeam data was corrected for the water column sound speed in real-time using the SIS control software. To determine the sound speed at the transducers, an Endeco YSI sonde was used on board the R/V C-Ghost, and an AML SV•Xchange was used on board the R/V Sea Scout. The sound speed data and confidence checks are located in Separates II Digital Data\Sound Speed Data Summary. Complete Coverage, Option 2: SSS data and concurrent MBES data, as outlined in the HSSD (2015) was acquired in the survey area. 100% SSS coverage was acquired in accordance with the requirements stated in the project instructions for this survey. On board the R/V Sea Scout, MBES data was acquired with a Kongsberg EM2040C echosounder and on board the R/V C-Ghost, MBES data was acquired with a Kongsberg EM3002 echosounder. A Klein 5000 V2 side scan sonar was used aboard the R/V Sea Scout and an EdgeTech 4200P side scan sonar was used aboard the R/V C-Ghost. A combination of complete MBES with backscatter and/or water column data and/or SSS data was collected for feature investigations. Density According to section 5.2.2.2 of the HSSD (2015) at least 80% of all nodes on the surface shall be populated with at least 5 soundings for Complete Coverage Option 2 surveys. The Compute Statistics tool in CARIS HIPS was used to generate statistics about the density child layer for the following surface: H12790_MB_1m_MLLW_Final (Figure 13). A bin size of 1 was used and the data exported in ASCII format. The number of nodes in the first 4 bins were added together to determine the number of nodes that contain less than 5 soundings. The H12790_MB_1m_MLLW_Final surface contains a total of 25,789,565 nodes and 25,681,127 nodes contain at least 5 soundings. Therefore, greater than 99.5% of all nodes on the surface contain at least 5 soundings. Figure 13. Statistical information about the density child layer of the H12790_MB_1m_MLLW_Final BASE surface, generated from the CARIS Compute Statistics tool. SupportFiles\Fig13_H90_Density.jpg 0.037 0.075 0.1873 0.000 1237094 2.00 n/a 0.8 JQN00023E707 2.00 n/a n/a Uncertainty of all components of the sounding measurement are included in the CARIS vessel file and detailed in the DAPR. CARIS HIPS was used to compute the Total Propagated Uncertainty (TPU) for each sounding. An Uncertainty layer child layer is generated during BASE surface creation that shows the uncertainty at each node of the surface. For additional review and quality control, two new layers were generated for each BASE surface that would become a finalized BASE surface. The two new layers were generated for the following surface: H12790_MB_1m_MLLW. The first layer was named <TVU_Maximum> and shows the maximum TVU at each node. The following formula was used during layer creation: ((0.5^2)+((0.013* Depth)^2))^0.5 The second layer generated was named <Uncertainty_QC> and defined as the difference between the TVU_Maximum and Uncertainty layers. Positive values indicate that the uncertainty is less than the TVU_Maximum and that the data meet specifications, while negative values indicate that the uncertainty is greater than the TVU_Maximum and that the data do not meet specifications. The two layers could have been combined into one for the Uncertainty_QC, as shown below for the finalized surfaces, but the TVU_Maximum layer also aided in determining the designation or examination status of critical soundings. The uncertainty for the H12790_MB_1m_MLLW BASE surface ranges from 0.12 – 0.32 meters. The Uncertainty_QC layer of the BASE surface shows all positive values, which demonstrates that all uncertainty values are less than the maximum TVU for each node. An Uncertainty_QC_Final layer was also generated for all finalized surfaces, defined by the equation below: (((0.5^2)+(0.013* Depth)^2)^0.5)- Uncertainty The uncertainty for the H12790_MB_1m_MLLW_Final surface ranges from -1.10 to 0.32 meters. A text file was exported from CARIS and run through a python script to determine the percentage of Uncertainty_QC_Final values that are less than zero, which indicates that the uncertainty values at those nodes exceed specifications. Analysis of the Uncertainty_QC_Final layer for the H12790_MB_1m_MLLW_Final BASE surface indicates that less than 0.01% of nodes have an uncertainty greater than the maximum allowable TVU. It was observed that all uncertainty values are within specification for the un-finalized surfaces, but contain a small portion of values that are out of specification when finalized. The reason is due to the finalization parameter, where the uncertainty is defined as the greater of either the standard deviation or uncertainty for a particular node. Note that when the surfaces are finalized, the TVU_Maximum and Uncertainty_QC layers are retained but Uncertainty_QC layer does not reflect the new Uncertainty values of the finalized surface. These layers can be removed, but if the finalized BASE surface is recomputed, it appears that these layers will be regenerated (after closing and re-opening the project). For this reason, the layers were not removed from the finalized surfaces All corrections to echo sounding (instrument corrections, static and dynamic draft, speed of sound, and attitude corrections) follow the procedures outlined in the accompanying Data Acquisition and Processing Report (DAPR). Prior to initiating survey operations, a standard patch test was performed for each vessel to determine correctors for pitch, roll, and heading (additional calibrations were performed as necessary). Squat and settlement tests were also conducted to determine the dynamic draft of the vessels. Refer to the Data Acquisition and Processing Report for additional information. Patch Test - Sea Scout 2015-04-29 Multibeam calibration Squat Test - Sea Scout 2015-06-11 Determine squat of vessel due to speed Patch Test - C-Wolf 2015-09-06 Multibeam calibration Patch Test - C-Ghost 2015-09-03 Multibeam calibration Squat Test - Sea Scout 2015-06-11 Determine squat of vessel due to speed Squat Test - C-Wolf 2016-01-15 Determine squat of vessel due to speed Squat Test - C-Ghost 2015-03-18 Determine squat of vessel due to speed Backscatter was logged within each raw Kongsberg EM file. This data was imported during CARIS conversion and reviewed when necessary. Backscatter mosaics of the EM3002 data were able to be generated using CARIS. The EM2040C data was unable to be processed in CARIS; there is currently an open service request regarding this issue. All backscatter was imported and mosaics generated using FMGT version 7.5.1. Processing limitations necessitated the generation of several small mosaics instead of a mosaic of the entire area. Please note that errors were encountered with lines H90-c_4, H90-c_5, H90-c_5a and H90-c_6. Errors were also encountered in CARIS with these lines and the lines were removed from both the FMGT and CARIS projects. NOAA Extended Attribute Files V5_3_2. Software updates are detailed in the DAPR. No further software updates occurred after the submission of the DAPR. H12790_MB_1m_MLLW Uncertainty 1 7.52 11.82 Q/C Complete Coverage H12790_MB_1m_MLLW_Final Uncertainty 1 6.78 11.82 Complete Coverage H12790_MB_2m_MLLW Uncertainty 2 7.67 11.70 Survey Junctions H12790_MB_5m_MLLW Uncertainty 5 7.68 11.63 Survey Junctions H12790_MB_Mainlines_1m_MLLW Uncertainty 1 7.52 11.64 QC H12790_MB_Crosslines_1m_MLLW Uncertainty 1 7.70 11.61 QC Data Quality Control After initial data cleaning, the surfaces were reviewed a second time for fliers using the standard deviation layer and the 3D display window, when necessary. Higher standard deviation is generally associated with bathymetric features, contacts and/or areas of bathymetric change. Areas of noisy MBES data, although cleaned, can also show higher standard deviation. The highest standard deviation of 0.83 m is located at 29.013N, 91.566W and associated with a contact. This contact is within an area containing many contacts (refer to section D.2.7 and the Final Feature File for additional information) and is located between two (2) charted 28 foot obstructions. A complete description of the horizontal and vertical control for the OPR-K379-KR-15 surveys is located within the accompanying Horizontal and Vertical Control Report (HVCR). A summary of the horizontal and vertical control is provided below. Mean Lower Low Water (MLLW) Discrete Zoning LAWMA, Amerada Pass, LA 8764227 8764227.tid Verified Observed K379KR2015CORP.zdf Final 2016-01-25 2016-01-25 Preliminary zoning is accepted as the final zoning for project OPR-K379-KR-15 as outlined in the Tides and Water Levels Statement of Work section 1.5.1. This zoning was used for data collected in 2015 only. VDatum PS_HAE_Reduction_to_MLLW_CGhost.tid and GPS_HAE_Reduction_to_MLLW_SeaScout.tid Data collected in 2016 was corrected using primary C-Nav GPS ellipsoid heights reduced to MLLW. The files used to correct the 2016 data are named in Tables 14 and 15. Refer to the DAPR for a detailed explanation. North American Datum of 1983 15N Single Base The C-Nav GPS systems aboard the vessels receive corrections through the C-Nav Subscription Services. This is “a premier worldwide subscription service providing 5 cm or better positioning accuracy. GNSS corrections are broadcast via Inmarsat geostationary satellites, providing highly accurate and reliable positioning coverage from 72 degrees north to 72 degrees south latitude.” (http://www.cnavgnss.com/products) User defined color range charts and a selected sounding layer were used to compare surveyed soundings to charted depths. The shoal biased selected sounding layer was generated with a single defined radius of 150 meters. 11340 49 458596 79 2016-02 2016-03-22 2016-03-26 11340 Two (2) Local Notice to Mariners (LNM) were issued within the survey bounds subsequent to the date of the project instructions and before the end of the survey (LNM 06/16 9th Dist on 2/11/2016). These two previously uncharted features were observed during survey operations and submitted as H12790_DtoN_Submission1. More information regarding these obstructions can be found in the Final Feature File. The last Local Notice to Mariners reviewed was LNM 07/16 8th Dist - Chart: 11340, Current Edition: 79 Print Date: Feb. /2016, Mississippi River to Galveston. Surveyed soundings range from 4.11 – 6.47 fathoms (7.52 – 11.82 meters). Depths increase from northwest to south-southeast within the survey area. User defined color range charts and a selected sounding layer were used to compare surveyed soundings to charted depths. The shoal biased selected sounding layer was generated with a single defined radius of 150 meters. On chart 11340, the 5 fathom contour extends from west to east through the southern portion of the survey area. It is evident from survey data that the 5 fathom contour has shifted north of its current position, particularly in the eastern portion of the survey area (Figure 14). Figure 14. Comparison between surveyed soundings and charted 5 fathom contour. Blue represents area where surveyed soundings are greater than 5 fathoms (9.144 m) and green represents area where surveyed soundings are less than 5 fathoms. SupportFiles\Fig14_H90_ChartComparison_11340.jpg 11351 63 80000 43 2012-03 2016-03-22 2016-03-26 11351 Four (4) Local Notices to Mariners (LNM) were issued within the survey bounds subsequent to the date of the project instructions and before the end of the survey. LMN 37/15 8th Dist issued on 9/24/2015 to ‘Delete Platform (Fieldwood-103-20)’. This platform was removed before the start of H12790 survey operations, and was not present at the time of survey. LNM 06/16 8th Dist issued on 2/4/2016 included addition of a 31-foot and a 28-foot obstruction, as well as removal of a 32-foot charted depth in the location of the new 28-foot obstruction. These notices correspond to H12790_DtoN_Submission1, and more information can be found in the Final Feature File. The last Local Notice to Mariners reviewed was LNM 06/16 8th Dist - Chart: 11351, Current Edition: 43 Print Date: Mar. /2012, Point au Fer to Marsh Island. Surveyed depths range from 24.67 to 38.81 feet (7.52 – 11.82 meters). In general, surveyed soundings are 1 – 3 feet deeper than charted depths throughout the survey area. In the southwest corner of the survey area, some surveyed soundings are up to 5 feet deeper than charted depths. The charted 30 foot contour extends from west to east through the southern portion of the survey area. It is evident from the survey data that the contour has shifted north of its current position, particularly in the eastern portion of the survey area (Figure 15). Figure 15. Comparison between surveyed soundings and the 30 foot contour of chart 11351. Green represents areas where surveyed soundings are less than 29.75 feet (9.143 m) in depth and blue represents areas where surveyed soundings are 29.75 feet (9.143 m) in depth and greater. SupportFiles\Fig15_H90_ChartComparison_11351.jpg 11356 62 80000 41 2014-07 2016-03-22 2016-03-26 11356 No Local Notices to Mariners were issued within the survey bounds subsequent to the date of the project instructions and before the end of the survey. The last Local Notice to Mariners reviewed was LNM 03/16 8th Dist - Chart: 11356, Current Edition: 41 Print Date: Jul. /2014, Isles Dernieres to Point au Fer. Only the eastern edge of the survey area overlaps with chart 11356 and surveyed soundings in this area are 1 – 3 feet deeper than charted depths. This area of overlap is also covered by survey H12789; refer to the H12789 descriptive report for a detailed chart comparison. Figure 16. Comparison between surveyed soundings and 11356 charted depths, including the 30 foot contour. Green represents areas where surveyed soundings are less than 29.75 feet (9.143 m) in depth and blue represents areas where surveyed soundings are 29.75 feet (9.143 m) in depth and greater. SupportFiles\Fig16_H90_ChartComparison_11356.jpg US4LA21M 80000 27 2015-03-25 2016-02-02 false US4LA21M Depths and contours on ENC US4LA21M generally match those of chart 11351. The observations made between surveyed soundings and depths on chart 11351 are valid for the ENC. The only observed differences in depths between the ENC and RNC 11351 exists in the southern region that is outside the survey bounds, but was covered with survey data. Surveyed soundings are up to 5 feet deeper than ENC depths (Figure 17). AWOIS item investigations are not assigned for this project. No Maritime Boundary Points were assigned for investigation within H12790 survey bounds. Chart 11340 There are two (2) charted obstructions within the survey area that correspond to DtoNs submitted for H12790. Two additional charted obstructions exist that are outside the survey bounds, but were covered with survey data. One (1) of these obstructions correlates to a DtoN submission for H12789 and is corroborated with survey data from H12790. The other obstruction, centered at 29.016N, 91.568W was not observed within survey data, though a portion of the charted 4 ¾ fathom obstruction area did not receive complete survey coverage. Refer to the Final Feature File for additional information. Chart 11351 There are four (4) charted platforms and numerous charted pipelines within the survey area (refer to sections D.2.6 and D.2.4, respectively for additional information). There is also one (1) 31 foot obstruction and one (1) 28 foot obstruction charted within the survey area. One (1) 25 foot obstruction and one (1) 28 foot obstruction are charted outside survey bounds, but were covered with survey data; the 28 foot obstruction was not observed within survey data. Refer to the Final Feature File for additional information. Chart 11356 No additional charted features than what was previously described for charts 11340 and 11351 exist on chart 11356. Previously described feature remarks are valid for chart 11356. US4LA21M The charted pipelines on ENC US4LA21M match those of RNC 11351. The four obstructions, and the four charted platforms on RNC 11351 are also present on the ENC USLA21M. Refer to the Final Feature File for additional information. No additional features are observed on the ENC that are not charted on the RNC. Two (2) uncharted Dangers to Navigation were submitted and there are numerous contacts that required sounding designation in the CARIS project. Refer to the Final Feature File for additional information. 2 Two (2) Dangers to Navigation were submitted for survey H12790. Refer to the Final Feature File for additional information. No additional shoal or hazardous features were observed visually or within survey data that have not been discussed in sections D.1.6, D.1.7, D.2.4, D.2.6 or D.2.7. No channels are currently charted within the survey limits, and none were observed during survey operations. Five (5) bottom samples were collected within the limits of H12790. Refer to the Final Feature File for additional information. There is no Shoreline Verification for this survey. Prior survey data was not required to be evaluated for this survey. No Aids to Navigation are currently charted within the survey area, and none were observed either visually or within survey data. Overhead features do not exist for this survey. Numerous submarine pipelines are charted within the H12790 survey area. Several potential exposures were observed within survey data (SSS and/or MBES) and were further investigated. Refer to the Final Feature File for additional information. There is one submarine cable charted within the survey area but evidence of this cable was not observed within survey data. No ferry routes or terminals are currently charted within the survey limits, and none were observed during survey operations. There are four (4) platforms charted within the bounds of H12790. Two (2) of these platforms were observed visually and within survey data and are near currently charted platforms. Two (2) of these platforms were not observed visually or within survey data and the hydrographer recommends removal from the chart. There is one (1) additional platform in the CSF file but it is not currently charted. This platform was not observed visually or within survey data. One (1) charted platform outside the southwest survey bounds was covered with survey data and was observed visually and within survey data. Refer to the Final Feature File for additional information. Along the southwest boundary of the survey area there is a high concentration of contacts that were either designated or marked as examined in the CARIS project. Due to the high concentration of contacts, some of the smaller features were not chosen as individual contacts from the SSS data. This has been represented as an area feature in the Final Feature File. Two water column anomalies were discovered during the survey and submitted for information purposes. Data representative of the anomaly were rejected from the CARIS project. Both anomalies have been included in the Final Feature File. The water column anomaly located at 29.074N, 91.562W was covered with multibeam data on four (4) different occasions between October 12, 2015 and February 18, 2016. On October 12th, a 1.8-meter depression was evident. By February 18th the depression had filled in. Coverage on the 7th of November and the 25th of January show the gradual filling in of this depression. Though no longer present, this depression is represented as an area feature in the Final Feature File. No active dredging or construction was observed during survey operations. No new surveys or investigations are recommended for this area. No new insets are recommended for this area. Field operations contributing to the accomplishment of the H12790 survey were conducted under my direct supervision with frequent personal checks of progress and adequacy. This report and CARIS project have been closely reviewed and are considered complete and adequate as per the Statement of Work. This report is accompanied by the Data Acquisition and Processing Report for project OPR-K379-KR-15. Tara Levy Chief of Party 2016-04-16 Nicole Galloway Geoscientist 2016-04-16