OPR-K339-KR2-14 Barataria Bay to Southwest Pass, LA Barataria Bay to Southwest Pass Fugro Pelagos, Inc. H12715 2 The Hydrographic Sheet should be accompanied by this form, filled in as completely as possible, when the sheet is forwarded to the Office 6 NM SW of Bastin Bay Louisiana United States 40000 2015 Dean Moyles Navigable Area 2014-11-21 2014-12-08 2015-06-30 Multibeam Echo Sounder Multibeam Echo Sounder Backscatter meters UTM UTC Pacific Hydrographic Branch Contractor The project area is referred to as Priority 2 "6 NM SW of Bastian Bay" within the Project Instructions. 29.242 89.720 29.065 89.501 Survey Limits were acquired in accordance with the requirements in the Project Instructions and the HSSD. Overview of Project OPR-K339-KR2-14 Support Files\H12715_OverviewFigure.png The purpose of this survey is to update existing NOS nautical charts in a high commercial traffic area. This area is within an area of very active coastal restoration efforts with the BP Deep Water Horizon RESTORE program as well as other restoration programs. Large amounts of dredging are seen in this area in addition to oil and gas navigation and production activities and the large population of commercial fishing and trawling seen in this area. A newer consideration is the recreational and sport boating and imaging of near shore fisheries habitat which is increasing in activity and in scientific studies of the area.. This project will cover approximately 113 square nautical miles of which, 68 are "Critical" and 40 are “Priority 1” survey areas as designated in the NOAA Hydrographic Survey Priorities, 2012 edition. The project area is located in the Gulf of Mexico near Southwest Pass, LA & Barataria Bay, LA. The entire survey is adequate to supersede previous data. Survey Coverage was in accordance with the requirements in the Project Instructions and the HSSD. It should be noted that data holidays are present around existing platforms and are due to vessel maneuvering and/or removal of the platform legs from the data set. H12715 Survey Coverage Support Files\H12715_CoverageFigure.png 556510 0 326.3 0 0 0 0 0 0 0 1120138 0 1991 0 0 0 0 0 98.4 0 0 2317.3 0 0 0 0 0 98.4 0 4.2 8 0 0 0 0 0 2014-12-08 2014-12-09 2014-12-10 2014-12-11 2015-02-23 2015-02-24 2015-06-03 2015-06-04 2015-06-05 2015-06-06 2015-06-07 2015-06-08 2015-06-09 2015-06-10 2015-06-11 2015-06-12 2015-06-13 2015-06-14 2015-06-15 2015-06-16 2015-06-17 2015-06-18 2015-06-19 2015-06-20 2015-06-21 2015-06-22 2015-06-23 2015-06-24 2015-06-25 2015-06-26 2015-06-27 2015-06-28 2015-06-29 2015-06-30 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, and any deviations from the DAPR are discussed in the following sections. 556510 122 7 1120138 150 10 The Geodetic Surveyor and Go America acquired all sounding data for survey H12715. Note: The Geodetic Surveyor (556510) was utilized November 26, 2014 through December 11, 2014 and February 23, 2015 through February 24, 2015. Due to scheduling conflicts and engine issues, the Geodetic Surveyor was demobilized in May 2015. The equipment and a work container were then mobilized on the Go America (1120138) and work commenced May 17, 2015. Applanix POS M/V v4 Positioning and Attitude System Reson 7125 MBES Reson SVP 70 Sound Speed System Ocean Science UCTD Conductivity, Temperature and Depth Sensor Applied Micro-Systems SV&P Sound Speed System WaterLOG H3611 (Radar Water Level Sensors) were installed on the port and starboard gunwales of the Geodetic Surveyor and Go AmericaM/V Ocean Pioneer to obtain a more precise static draft measurement. Samples were taken over a 10 minute period and averaged to determine the vessel’s draft. Traditional static draft measurement techniques were also employed as a substitute for the WaterLOG H3611 measurements when required. It should be noted that both vessels were equipped with dual Reson 7125 sonars, which were operated in the full rate dual head (FRDH) mode in the Reson topside. Crosslines were planned and well distributed throughout the survey to ensure adequate quality control. Total crossline length surveyed was 98.4 nautical miles or 4.2 percent of the total mainscheme line length. Each crossline was compared to the entire mainscheme line plan through a 2m CUBE surface using the CARIS HIPS QC report routine. Additionally, a Difference Surface was generated using the CARIS HIPS Difference Surface function; comparing the depths from the 2-meter resolution BASE surface of H12715 mainscheme lines versus a 2-meter resolution BASE surface of H12715 Crosslines. Using the Compute Statistics function in CARIS, the difference surface yielded the following results: standard deviation of 0.05 meters, and a mean difference of 0.0 meters. All of the QC Reports fall well within the required accuracy specifications. H12715 Crossline Overview Support Files\H12715_Crossline_OverfiewFigure.tif H12715 Crossline Difference Surface Overview Support Files\H12715_Crossline_OverViewDiffFigure.tif H12715 Crossline Difference Surface Histogram and Statistics Support Files\H12715_Crossline_FigureHistogram.tif 0.1 0.23 Go America 6.634 0 0.25 Geodetic Surveyor 2.620 0 0.25 The majority of the data fell within IHO Order 1a accuracy specifications. Nodes that exceeded the allowable specifications were located in areas where the outer beams of the coverage boundaries were the single contributor to the surface and a small portion attributable to rapid topographical changes such as scouring, exposed pipelines, etc. Note: Total propagated uncertainty were derived from a combination of real time and fixed values for equipment, vessel characteristics, sound speed, and tide and tide zoning. The percentage of nodes within IHO Order 1a, were computed by CARIS using the Surface QC Report utility and are as follows: Surface Depth Range (m) % of nodes within IHO Order 1a H12715_MB_50cm_Final 0 - 22 m >99.99% H12715 Uncertainty Support Files\H12715_IHO1Figure.tif Overview of Survey Junctions for H12715 Support Files\H12715_Junction_OverviewFigure.png H12716 40000 2015 FPI S Survey H12716 borders the southern boundary of H12715. The conformity between H12715 and the junction survey H12716 was inspected during processing, using CARIS HIPS’ Subset Editor routine and finalized BASE Surfaces. A difference surface was generated using the CARIS HIPS Difference Surface function; comparing the depths from the 2-meter resolution BASE surface of the H12715 and H12716 surveys. Using the Compute Statistics function in CARIS, the difference surface yielded the following results: standard deviation of 0.06 meters, a mean difference of 0.11 meters, and divergences generally within 20 centimeters. The surveys are in agreement along their common borders and well within the total allowable vertical uncertainty and IHO Order 1a allowable error. The majority of difference between the two surveys can be attributed to sound speed and tide error with a small portion of difference attributable to error in vessel offsets. Junction between Survey H12716 and H12715 Support Files\H12716_Junction_Diff_Surface.png Stats comparing Survey H12716 and H12715 Support Files\H12715_H12716.png H12714 40000 2015 FPI W Survey H12714 borders the northwestern boundary of H12715. The conformity between H12715 and the junction survey H12714 was inspected during processing, using CARIS HIPS’ Subset Editor routine and finalized BASE Surfaces. A difference surface was generated using the CARIS HIPS Difference Surface function; comparing the depths from the 2-meter resolution BASE surface of the H12715 and H12714 surveys. Using the Compute Statistics function in CARIS, the difference surface yielded the following results: standard deviation of 0.04 meters, a mean difference of 0.02 meters, and divergences generally within 20 centimeters. The surveys are in agreement along their common borders and well within the total allowable vertical uncertainty and IHO Order 1a allowable error. The majority of difference between the two surveys can be attributed to sound speed and tide error with a small portion of difference attributable to error in vessel offsets. Junction between Survey H12714 and H12715 Support Files\H12714_Junction_Diff_Surface.png Stats comparing Survey H12714 and H12715 Support Files\H12715_H12714.png H11807 10000 2008 FPI W Survey H11807 borders the northwestern boundary of H12715. The conformity between H12715 and the junction survey (H11807) was inspected during processing, using CARIS HIPS’ Subset Editor routine and finalized BASE Surfaces. A difference surface was generated using the CARIS HIPS Difference Surface function; comparing the depths from the H12715 (2-meter resolution) BASE surface and the H11807 survey. Using the Compute Statistics function in CARIS, the difference surface yielded the following results: standard deviation of 0.09 meters, a mean difference of -0.09 meters, and divergences generally within 20 centimeters. The surveys are in agreement along their common borders and well within the total allowable vertical uncertainty and IHO Order 1a allowable error. The majority of difference between the two surveys can be attributed to sound speed and tide error with a small portion of difference attributable to error in vessel offsets. Junction between Survey H11807 and H12715 Support Files\H11807_Junction_Diff_Surface.png Stats comparing Survey H11807 and H12715 Support Files\H12715_H11807.png H11683 10000 2007 DEA N Survey H11863 borders the northern boundary of H12715. The conformity between H12715 and the junction survey (H11863) was inspected during processing, using CARIS HIPS’ Subset Editor routine and finalized BASE Surfaces. A difference surface was generated using the CARIS HIPS Difference Surface function; comparing the depths from the H12715 (2-meter resolution) BASE surface and the H11863 survey. Using the Compute Statistics function in CARIS, the difference surface yielded the following results: standard deviation of 0.59 meters, a mean difference of -0.09 meters, and divergences generally within 20 centimeters. The surveys are in agreement along their common borders and well within the total allowable vertical uncertainty and IHO Order 1a allowable error. The majority of difference between the two surveys can be attributed to sound speed and tide error with a small portion of difference attributable to error in vessel offsets. The high standard deviation is most likely due the post Hurricane Katrina beach replenishment site known as the Crater – Borrow (in Fugro’s GOM dBase) site on the southeast side of H12715. This is further discussed in section D.2.9 Construction and Dredging. Junction between Survey H11683 and H12715 Support Files\H11683_Junction_Diff_Surface.png Stats comparing Survey H11807 and H12715 Support Files\H12715_H11683.png Sonar system quality control checks were conducted as detailed in the quality control section of the DAPR. The Reson SeaBat 7125 sonar system displayed bottom-detection artifacts near nadir of the multibeam swath. The bottom detection algorithm in the Reson 7125 may have been affected by the time spreading of the signal return due to sediment penetration close to nadir. To mitigate these effects, the sonar pulse length was kept at low settings during acquisition and the artifacts were monitored closely during data processing to ensure all data met IHO Order 1a specifications. Subset of Soundings affected by sediment penetration close to nadir. Support Files\BottomDetectionArtifact_.png A general downward and/or upward cupping is noticeable in the across-track sounding profiles for certain areas. The sound speed refraction errors were seen in the outer beams on the majority of survey lines conducted and were on the order of 0.1 to 0.2 meters. These errors are a result of the survey area’s proximity to the Mississippi River, which not only carries sediment but also causes a change in the water surfaces temperature and salinity. The sound speed profiles conducted throughout the project had an increased inconsistency throughout the water column; this was much more evident at the surface or near face of the sonars. In order to mitigate these sound speed errors, the frequency of sound speed casts were increased and the line spacing reduced. Data were examined (and filtered) in CARIS HIPS’ Subset Editor routine to ensure the CUBE surface met IHO Order 1a specifications. Satellite image capturing river outflow (complements of NASA) Support Files\Aerial.png Photo captured during survey operations of the brakish surface layer Support Files\Brakish_Water.png There was an extremely high presence of marine life such as shrimp, dolphins, schools of fish, etc. in the survey area. This resulted in not only numerous in-fills and re-runs, but increased time spent on manually rejecting the erroneous data in CARIS HIPS and SIPS. Subset showing rejected soundings from dolphin interference Support Files\Dolphin_Interference.png Shallow (0-100ft BML) gas saturated sediments are normal bottom attributes in the GoM. The gases within shallow sediments are typically in a state of low pressure equilibrium, unless active percolation into the water column can be observed (common in remote sensing data). Active venting into the water column is fairly common (though it is typically episodic, not continuous), and is a function of sedimentary gas concentration, overburden, sediment shear strength, water pressure/depth, and other variables. Natural seeps can be either biogenic or thermogenic in origin. Thermogenic gas typically originates in deep source rocks and migrates to the surface via geologic conduits such as faults or gas chimneys. Biogenic gas is generally sourced from (geologically recent) decaying biomass that is trapped in near-surface sediments. Biogenic gas is more common in shallow (shelf) water depths of the GoM that have been subaerially exposed in the recent past. In deeper waters (300+ meters), chemosynthetic communities can use natural methane seeps to produce energy. High frequency energy tends to be attenuated when it passes through gas charged sediments. Sedimentary methane concentrations in excess of 30 ml/liter are sufficient to attenuate the 3.5 kHz seismic signals due to bubble phase scattering and absorption of the high frequency sound waves. Gas saturation in sediments tends to lower vane shear strength. Exaggerated surface and subset of area affected by Natural Organic Seeps Support Files\Subset_Gas_Seeps.png Small tide busts, on the order of 0.10m to 0.25m were noticed between some mainscheme lines, but were more apparent between the mainscheme and in-fill lines. In the graphic, mainscheme lines were conducted on Julian Day 166 and in-fills line conducted on Julian Day 179, you can see a 0.25 meter separation between the data set. This can be attributed to the overall uncertainly in the gauge and zoning data, but could also be attributed to weather induced tide errors, which are mentioned below. All data fell within IHO Order 1a accuracy specifications. Note: GPS Heights were applied to the data set and a GPS Tide Computed (referenced to the NAD83 ellipsoid), but this was for troubleshooting purposes only, mostly to verify tide bust. Final tide corrections for this survey were traditional tides and zoning. Tide offset Support Files\H12715_tideBust.png It was also normal to see weather induced tide errors on the order of 0.10 to 0.20m, during weather systems and isolated storms. From the graphic you can see on May 26, 2015 and May 27, 2015 the effects of these thunder storms. During these isolated storms, it was normal for the winds to increase to 20 or 25 knots thus increasing the sea state to three to four feet, which in turn had a direct effect on the tide measurement. All data fell within IHO Order 1a accuracy specifications Graph of weather induced tidal error Support Files\Weather_Induced_Tide_Error.png Small heave artifacts on the order of 0.05 to 0.10m are noticeable in the final CUBE surface. All survey lines had the true heave applied, but since this was an over the side pole mount, during times of increased sea state we would have some roll induced into the heave calculation. To remove this error, offsets for the reference to center of rotation (CoR) lever arm in the POS MV were used to calculate the total heave as the sum of the “AC Coupled” (and zero mean) heave at the vessel CoR plus any roll or pitch induced “DC Coupled” remote heave. Since this did not improve the results, these offsets were removed. All data fell within IHO Order 1a accuracy specifications. Exaggerated Surface and Subset of Roll Induced Heave Support Files\H12715_Heave.png An artificial trench was seen in data from nadir beams of the Reson 7125 system in areas with a bottom type of soft mud. Analysis of the data indicated that other Barataria Bay projects observed similar occurrences which contributed to returning false depths on the order of 5-10 cm. Bottom samples collected in the project area confirmed that the seabed was made up of soft mud. All data fell within IHO Order 1a accuracy specifications. Nadir sediment penetration Support Files\Nadir_Penetration.png Sonar settings (power, transmit pulse, and gain) were optimized for data quality and to meet the HSSD requirements. The sonars (rotated ~15 degrees) were configured to operate in the full rate dual head mode using the 400 kHz frequency using a low transmit pulse and low gain. Due to the factors mentioned above along with limiting the outer beams of the sonars and the soft muddy bottom, different filtering techniques were used to reject fliers and noise in the data set. For these reasons when the rejected data are displayed there is a high volume of rejected soundings in the water column. Refer to the Data Acquisition and Processing Report for further information. Sound speed measurements were conducted and applied as discussed in the Corrections to Echo Soundings section of the DAPR. All equipment and survey methods were used as detailed in the DAPR. The NOS Hydrographic Surveys Specifications and Deliverables, April 2014, requires 95% of all nodes to be populated with at least five soundings. Survey H12714 met these project specifications. Density requirements for H12715 were achieved with at least 99.98% of finalized surface nodes containing five or more soundings. Nodes that failed to meet the allowable specifications were located in areas containing gas saturated sediments, which resulted in natural seeps that could be either biogenic or thermogenic in origin. Other contributors are areas where the outer beams of the coverage boundaries were the single contributor to the surface. CUBE Surface Density Report Surface Depth Range (m) % of nodes within IHO Order 1a H12715_MB_50cm_MLLW_final 0 - 22 99.99% H12715 Data Density Support Files\H12715_Density_Figure.png All data reduction procedures conform to those detailed in the DAPR. All sounding systems were calibrated as detailed in the DAPR. 2015-09-21 Towed Side Scan Sonar (SSS) operations were not required by this contract, but the backscatter and beam imagery snippet data from all multibeam systems were logged and are stored in the s7k files. All beam imagery snippet data was logged in the 7028 record of the s7k file for the project. NOAA Extended Attributes Files V5_3_2 H12715_MB_50cm_MLLW CUBE 50 0 22 NOAA_0.5m Object Detection H12715_MB_50cm_MLLW_Final CUBE 50 8 21.02 NOAA_0.5m Object Detection The surfaces have been reviewed where noisy data, or 'fliers' are incorporated into the gridded solution causing the surface to be shoaler than the true seafloor. Where these spurious soundings cause the gridded surface to be shoaler than the reliably measured seabed by greater than the maximum allowable TVU at that depth, the noisy data have been rejected and the surface recomputed. The NOAA CUBE parameters mandated in HSSD were used for the creation of all CUBE BASE surfaces in Survey H12715. Additional information discussing the vertical and horizontal control for this survey can be found in the accompanying HVCR. Mean Lower Low Water Discrete Zoning Grand Isle 8761724 8761724.tid Final Approved K339KR22014CORP_Rev.zdf Final On July 20, 2015, verified tidal data for OPR-K339-KR2-14 was acquired from CO-OPS through NOAA tides and currents website (http://tidesandcurrents.noaa.gov/). All sounding data was then re-merged using CARIS HIPS and SIPS tide routine. Verified tidal data were used for all final CUBE Surfaces, soundings, and S-57 Feature files. It should be noted that, in addition to weather induced tidal errors as discussed in the Factors Affecting Soundings section, CO-OPS issued a revised zoning file (on December 5, 2014) that extended the limits of zone CGM370 in order to include the portion of the survey that extends past the existing boundary. NAD83 UTM16N Single Base For real-time corrections, the POS M/V was configured to accept Fugro’s Marinestar corrections; Marinestar is a decimeter level, phase based service using satellite ‘orbit and clock’ data valid worldwide, based upon GPS L1 and L2 frequencies, it provides a horizontal accuracy of 10 cm and vertical accuracy of 15 cm. The unit output corrected positions at 1 Hz to the (POS MV) 320 v4 where it was integrated with inertial data, and a position for the top-center of the IMU generated. The unit output differentially corrected positions at 1 Hz to the (POS MV) 320 V4 where it was integrated with inertial data, and a position for the top-center of the IMU generated. This position was logged concurrently with the bathymetry from WinFrog and the POS file using Fugro Pelagos PosMvLogger. It was later corrected for offsets to the multibeam echosounder (MBES) by CARIS HIPS in post-processing. Final positioning was done using post-processed kinematic (PPK) methods. Applanix POSPac MMS v6.2 software was used in conjunction with the POS files and the Grand Isle (GRIS) CORS base station data to generate a higher accuracy position, which was applied in processing to replace the real-time position records. 11358 60 80000 58 2014-05 2014-06-24 2014-07-05 A comparison was made between survey H12715 and Chart 11358 using a sounding layer generated CARIS 50-centimeter Combined CUBE surface. Chart information displayed is based on OPR-K339-KR2-14 Project Instructions, however the charts used for final comparison were downloaded on 06-25-2015. Given that the survey area was ensonified with 100% multibeam coverage, discrepancies were discovered between the charted and surveyed depths. Soundings generally agree to within 5 feet and disagreement trends toward survey H12715 having deeper depths than chart 11358. The Hydrographer recommends that soundings within the survey limits of H12715 supersede all prior survey and charted depths. Chart comparison H12715 vs. 11358 Support Files\H12715_chart.tif 11361 57 80000 77 2013-05 2014-06-17 2014-07-05 A comparison was made between survey H12715 and Chart 11361 using a sounding layer generated from a CARIS 50-centimeter Combined CUBE surface. Chart information displayed is based on OPR-K339-KR2-14 Project Instructions, however the charts used for final comparison were downloaded on 06-25-2015. General agreement was found between charted soundings and soundings for survey H12715. Soundings generally agree to within 5 feet and disagreement trends toward H12715 having deeper depths than chart 11361. Depths in the southeastern portion of the survey are significantly deeper (30 ft.) than the charted soundings in this area. This is most likely due the post Hurricane Katrina beach replenishment site known as the Crater – Borrow (in Fugro’s GOM dBase) site on the southeast side of survey H12715. This is further discussed in section D.2.9 Construction and Dredging. The Hydrographer recommends that soundings within the survey limits of H12715 supersede all prior survey and charted depths. Chart comparison H12715 vs. 11361 Support Files\H12715_chart_11361.tif US4LA32M 80000 31 2013-10-04 2014-06-25 false A comparison was made between survey H12715 and ENC US4LA32M using a sounding layer generated from a CARIS 2-meter Combined CUBE surface. General agreement was found between charted soundings and soundings for survey H12715. Soundings generally agree to within 5 feet and disagreement trends toward H12715 having deeper depths than previously charted. The Hydrographer recommends that soundings within the survey limits of H12715 supersede all prior survey and charted depths. H12715 vs. ENC US4LA32M Support Files\H12715_ENC.tif US4LA33M 80000 27 2013-08-21 2014-05-30 false A comparison was made between survey H12715 and ENC US4LA33M using a sounding layer generated from a CARIS 2-meter Combined CUBE surface. General agreement was found between charted soundings and soundings for survey H12715. Soundings generally agree to within 5 feet and disagreement trends toward H12715 having deeper depths than previously charted. Depths in the southeastern portion of the survey are significantly deeper (30 ft.) than the charted soundings in this area. This is most likely due the post Hurricane Katrina beach replenishment site known as the Crater – Borrow (in Fugro’s GOM dBase) site on the southeast side of survey H12715. This is further discussed in section D.2.9 Construction and Dredging. The Hydrographer recommends that soundings within the survey limits of H12715 supersede all prior survey and charted depths. H12715 vs. ENC US4LA33M Support Files\H12715_US4LA33M_ENC.tif No AWOIS items exist for this survey. No maritime boundary exists for this survey. There were five charted features within the limits of H12715. The wreck with label “PA” charted at 29-10-50N 089-40-11W on chart 11358 was not found during the H12715 survey. During field operations, no Wreck was present at this location, it should be noted that the area was ensonified with 200% MB coverage. This item was assigned in the Composite Source File (CSF); refer to the Field Features File for more information on the results and S57 encoding. The “Obstn PD (Wk rep 1972)” charted at 29-08-30N 089-38-00W on chart 11358 was not found during the H12715 survey. During field operations no, Obstruction (wreck) was present at this location, it should be noted that the area was ensonified with 200% MB coverage. This item was assigned in the Composite Source File (CSF); refer to the Field Features File for more information on the results and S57 encoding. The wreck with label “PA” charted at 29-08-03N 089-36-00W on chart 11358 was not found during the H12715 survey. During field operations, no Wreck was present at this location, it should be noted that the area was ensonified with 200% MB coverage. This item was assigned in the Composite Source File (CSF); refer to the Field Features File for more information on the results and S57 encoding. The wreck with label “PD” charted at 29-07-44N 089-34-15W on chart 11358 was not found during the H12715 survey. During field operations, no Wreck was present at this location, it should be noted that the area was ensonified with 200% MB coverage. This item was assigned in the Composite Source File (CSF); refer to the Field Features File for more information on the results and S57 encoding. The wreck with label “PA” charted at 29-05-59N 089-34-00W on chart 11358 was found during the H12715 survey. During field operations, a Wreck located in the vicinity of the charted feature, it should be noted that the area was ensonified with 200% MB coverage and a least depth obtained. This item was assigned in the Composite Source File (CSF); refer to the Field Features File for more information on the results and S57 encoding. H12715 Charted Features Support Files\H12715_ChartedFeatures.png No uncharted features exist for this survey. 1 2015-10-25 Danger to Navigation Reports are included in Appendix I of this report. No shoals or potentially hazardous features exist for this survey. 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. Samples were taken with a Van Veen grab sampler and positions were recorded with WinFrog Multibeam. Samples retrieved were analyzed and then encoded with the appropriate S-57 attributes. Positions and descriptions of bottom samples for survey H12714 are found in the “H12715_Field_Features_File.000” file. It should be noted that SBDARE items in the composite source file were not assigned and were not investigated during field operations. Bottom samples were conducted in accordance with the HSSD Section 7.1 using the assigned locations, which were received on November 24, 2014. Shoreline was not assigned in the Hydrographic Survey Project Instructions or Statement of Work. No prior survey comparisons exist for this survey. Aids to navigation (ATONs) do not exist for this survey. Overhead features do not exist for this survey. Numerous pipelines exist within the surveys limits. Upon observing the CUBE surface and overlaying the as-laid pipeline Dbase during routine subset cleaning, it was apparent that a number of pipes were exposed. The graphic shows an example of an exposed pipeline in H12715. H12715 Exposed pipeline Support Files\H12715_ExposedPipeline.tif No ferry routes or terminals exist for this survey. There were numerous drilling and production platforms within the survey. Although none were assigned in the CSF file provided by NOAA, all existing platforms within the survey limits were boxed in and positioned. In the submitted Field Features Files (FFF); platforms that no longer exist were given a “delete” value in the “descrp” attribute. Platforms that were positioned incorrectly were also given the “delete” value in the “descrp” attribute, and a new platform feature with a “new” value in the “descrp” attribute was added at its correct location. There was an unexpected current in the area at times, which was not necessarily correlated with the tide. It was not uncommon to get a 1.5 to 2.5 knot current that was predominantly from a Southeasterly direction. It was also normal to see weather induced tide errors on the order of 0.10 to 0.20m, especially during weather systems and isolated storms. From the graphic you can see on May 26, 2015 and May 27, 2015 the effects of these thunder storms. During these isolated storms, the winds would increase to 20 to 25 knots thus increasing the sea state to three to four feet, which in turn had a direct effect on the tide measurement. Graph of weather induced Tidal Error Support Files\WeatherInducedTide.png There was no current dredging being undertaken during the time when the OPR-K339-KR2-14 survey was being conducted, but it was apparent from the MB data that there was dredging conducted in previous years. The West Delta (WD) Area was used in support of berm construction on some of the barrier islands following the Macondo incident. Barges would dump loads of sand and then a dredge would pump the sand ashore to build the berms. One of the re-handling sites was located in the east-central portion of WD20 near the block line with WD21. An area labeled “Crater Borrow” on our pipeline Dbase also shows signs of dredging, most likely for beach replenishment, you can see from the graphic the area on the southeast portion of H12715. Re-handling Site Support Files\H12715_rehandlingSite.tif Crater Borrow Site Support Files\H12715_Crater_BorrowSite.png There were a total of one-hundred and twenty features included in the Composite Source File (CSF) provided by NOAA, only eleven were assigned; one of those being outside the survey area. It should be noted that all features within the survey limits were investigated. In the submitted Field Features Files (FFF); features that no longer exist were given a “delete” value in the “descrp” attribute. Features such as platforms that were positioned incorrectly were also given the “delete” value in the “descrp” attribute, and a new platform feature with a “new” value in the “descrp” attribute was added at its correct location. For H12715, there were a total of 61 features; all were addressed. Any additional features are as attributed in the Field Features File. 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 and Specifications Deliverables Manual, Field Procedures Manual, Standing and 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. Dean Moyles Senior Hydrographer (ACSM Cert. No. 226) 2015-10-30 Coast Pilot Report 2015-10-30 Data Acquisition and Processing Report 2015-10-30 Horizontal and Vertical Control Report 2015-10-30