Table 1. Sequence of bubble and dredging tests with prevailing tide stage and number of bucket cycles recorded for each test. Test Tide Dredge Orientation 1 Date Time # Bucket Cycles Bubble 1 Flood North Jan 29 945-145 23 Bubble 2 Slack (high) North Jan 29 13-133 16 Bubble 3 Ebb North Jan 29 153-1615 2 Short Term 1 Flood North Jan 29 1115-1215 24 Short Term 2 Slack (high) North Jan 29 14-145 26 Short Term 3 Ebb North Jan 29 163-17 15 Long Term 1 Long Term 2 Long Term 3 Flood to Slack (high) to Ebb Slack (low) to Flood then Slack (high) to Ebb Slack (low) to Flood South Jan 3 815-163 145 South Jan 31 8-163 125 South Feb 1 745-1615 194 Instruments Used Bucket = OBS (s/n 36) Platform = OBS Surf (s/n 71) OBS Mid (s/n 37) OBS Bottom (s/n 29) Bucket = OBS (s/n 38) Platform = OBS Surf (s/n 71) OBS Mid (s/n 37) OBS Bottom (s/n 36) Bucket = OBS (s/n 29) Platform = OBS Surf (s/n 71) OBS Mid (s/n 37) OBS Bottom (s/n 36) Bucket = OBS (s/n 38) Platform = OBS Surf (s/n 71) OBS Mid (s/n 37) OBS Bottom (s/n 36) Bucket = OBS (s/n 38) Platform = OBS Surf (s/n 71) OBS Mid (s/n 37) OBS Bottom (s/n 36) Bucket = OBS (s/n 38) Platform = OBS Surf (s/n 71) OBS Mid (s/n 37) OBS Bottom (s/n 36) Bucket = OBS (s/n 38) Platform = OBS Surf (s/n 71) OBS Mid (s/n 37) OBS Bottom (s/n 36) Bucket (inboard) = OBS (s/n 29) Bucket (Outboard) = OBS (s/n 38) Platform = OBS Surf (s/n 71) OBS Mid (s/n 37) OBS Bottom (s/n 36) Bucket (inboard) = OBS (s/n 29) Bucket (Outboard) = OBS (s/n 38) Platform = OBS Surf (s/n 71) OBS Mid (s/n 37) OBS Bottom (s/n 36) 1 Dredge orientation refers to the approximate direction that the bow of the dredge platform and bucket were facing. 44
Table 2. Summary of bucket descent and ascent speeds during the long-term dredging tests. Bucket Speed Descent Ascent (feet/second) Mean (Range) Mean (Range) Long-Term Test #1 4.15 (2.2 5.4) 2.13 (1.85 2.24) Long-Term Test #2 4.44 (1.71 5.43) 2.17 (2.3 2.25) Inboard Long-Term Test #2 4.32 (2.45 5.15) 2.15 (2.9 2.2) Outboard Long-Term Test #3 4.36 (2.3 5.3) 2.13 (1.53 2.19) 45
a) Basic Option 9 Outer Side Slope B3 B2 Option 1 B1 Option 11 Option 12 C A2 Outer Side Slope D A1 b) Figure 1. a) Option areas of the S-NB-1 Contract area of the NY/NJ Harbor Deepening Project and b) bathymetry of S-NB-1 dredge contract area during the Pilot Study. 46
Figure 2. Cable Arm bucket in the open position. Note that the lowest row of vents has been closed by welding metal strips across the flaps. 47
Figure 3. Cable Arm bucket in the closed position. 48
Figure 4. Bucket impact position for a typical series of four arcs conducted between advances of the dredge. A sequence of 2 bucket cycles is shown as numbered green dots. The example progression is based on an actual DGPS record of bucket impact points during a long-term test on January 3, 28. The color coded rectangles centered on each dot represent the approximate plan-view dimensions of the bucket in the open position as it would come in contact with the bottom. 49
Figure 5. Plan-view distribution of bucket impact points on the bottom in relation to orientation of the receiving scow. Each numbered green dot represents a single bucket impact location based on DGPS offset data derived from a known reference point on the derrick. The scow is not drawn to scale. The numbered red dots represent non-digging bucket cycles used to collect water to wash the deck of the scow. Data from long-term dredging test on January 3, 28. 5
Figure 6. Instrumentation as mounted on the bucket. Upper orange canister contains an accelerometer array. Lower white and black unit is a battery-powered optical backscatter sensor (OBS-3A) with the sensor facing laterally outward from the central bucket support rib and outboard in relation to the bucket s internal axis. When the bucket was closed the instruments were oriented horizontally. When the bucket was open the instruments were oriented at an approximately 45 degree angle from the vertical. 51
Figure 7. Sensor location. The orange accelerometer canister and white OBS housing are visible atached to the bucket s central support rib. This sensor array is on the inboard side of the bucket, which always faces the derrick and operator s cab. 52
Figure 8. Location of sensors deployed from the dredge platform. The vertical tube supports the ADCP transducer asembly just below the water s surface. A string of three OBS units was deployed outboard from the ADCP mount. 53
15. Surface MidWater Bottom 1. 5.. 8:: 8:5: 8:1: 8:15: 8:2: 8:25: 8:3: 8:35: 8:4: 8:45: Time of Day, EST Figure 9. Example of ambient turbidity data collected by platform OBS units on January 31, 28. 54
Figure 1. ADCP backscatter signal during the ebb tide bubble test on January 29, 28. 55
Figure 11. ADCP backscatter signal during the slack tide bubble test on January 29, 28. 56
Figure 12. ADCP backscatter signal during the flood tide bubble test on January 29, 28. 57
1. 9. 8. 7. Surface MidWater Bottom Closure 6. 5. 4. 3. 2. 1.. 9:45: 1:: 1:15: 1:3: Time (EST) Figure 13. Turbidity measurements obtained by OBS instruments deployed from the dredge platform during the first bubble test, which occurred on a flooding tide on January 29, 28. 58
1. 9. 8. 7. Surface MidWater Bottom Closure 6. 5. 4. 3. 2. 1.. 12:45: 13:: 13:15: 13:3: 13:45: Time (EST) Figure 14. Turbidity measurements obtained by OBS instruments deployed from the dredge platform during the second bubble test, which occurred during slack tide on January 29, 28. 59
1. 9. 8. 7. Surface MidWater Bottom Closure 6. 5. 4. 3. 2. 1.. 15:3: 15:45: 16:: 16:15: Time (EST) Figure 15. Turbidity measurements obtained by OBS instruments deployed from the dredge platform during the third bubble test, which occurred on an ebbing tide on January 29, 28. 6
-2-4 Depth (m) -6-8 -1-12 -14 1 1 1 1 Figure 16. Turbidity data plotted against depth for bucket-mounted OBS instrument for all bubble tests. Note logarithmic scale of X-axis. 61
1. 9. 8. Avg 7. 6. 5. 4. 3. 2. 1.. 2 4 6 8 1 12 14 Depth Bin Figure 17. Average turbidity measurements by depth strata for a bucket-mounted OBS instrument during all bubble tests. 62
1 1 1 1 13:12: 13:13: 13:14: 13:15: 13:16: 13:17: 13:18: TIME (EST) Figure 18. A typical series of turbidity measurements from a bucket-mounted OBS instrument during a bubble test. Yellow triangles represent synchronized bucket closure times. The gap between successive bucket cycles result from deletion of measurements made while the bucket was above the surface of the water. 63
8 7 6 5 4 OBS 38 Closure 3 2 1 11:: AM 11:1: AM 11:2: AM 11:3: AM 11:4: AM 11:5: AM 12:: PM 12:1: PM Time (EST) Figure 19. Turbidity measurements obtained from the bucket mounted OBS Unit during the first short-term duration dredging test (flood tide) on January 29, 28. 64
8 7 6 5 4 OBS 38 Closure 3 2 1 1:5: PM 2:: PM 2:1: PM 2:2: PM 2:3: PM 2:4: PM 2:5: PM 3:: PM Time (EST) Figure 2. Turbidity measurements obtained from the bucket mounted OBS Unit during the second short-term duration dredging test (high slack tide) on January 29, 28. 65
12 1 8 6 OBS 38 Closure 4 2 4:2: PM 4:3: PM 4:4: PM 4:5: PM 5:: PM 5:1: PM Time (EST) Figure 21. Turbidity measurements obtained from the bucket mounted OBS Unit during the third short-term duration dredging test (ebb tide) on January 29, 28. 66
8 7 6 5 4 3 2 1 2 4 6 8 1 12 14 16 Depth (m) Figure 22. Turbidity measurements plotted versus depth and obtained from the bucket mounted OBS Unit during the first short-term duration dredging test (flood tide) on January 29, 28. 67
8 7 6 5 4 3 2 1 2 4 6 8 1 12 14 16 Depth (m) Figure 23. Turbidity measurements plotted versus depth and obtained from the bucket mounted OBS Unit during the second short-term duration dredging test (high slack tide) on January 29, 28. 68
12 1 8 6 4 2 2 4 6 8 1 12 14 16 Depth (m) Figure 24. Turbidity measurements plotted versus depth and obtained from the bucket mounted OBS Unit during the third shortterm duration dredging test (ebb tide) on January 29, 28. 69
1 4 9 8 7 6 5 4 FLOOD HIGH SLACK EBB LOW SLACK FLOOD HIGH SLACK EBB 3.5 3 2.5 2 1.5 ELEVATION (FT) 3 2 1 1.5 8:: 9:: 1:: 11:: 12:: 13:: 14:: 15:: 16:: 17:: TIME (EST) Figure 25. Turbidity measurements obtained by a bucket-mounted sensor during the first long-term dredging test on January 3, 28. 7
1 9 8 7 Descending Ascending Digging Moving 6 5 4 3 2 1 1 2 3 4 5 6 7 8 9 1 11 12 13 14 15 Depth (m) Figure 26. All turbidity measurements obtained by a bucket-mounted sensor during the first long-term dredging test on January 3, 28. 71
1 9 8 Descending Ascending Digging 7 6 5 4 3 2 1 1 2 3 4 5 6 7 8 9 1 11 12 13 14 15 Depth (m) Figure 27. Bucket-mounted turbidities during the first long-term dredging test on January 3, 28; descent, ascent and dredging data only. 72
1 Descending 9 8 7 y = -16.977x + 328.25 R 2 =.142 6 5 4 3 2 1 1 2 3 4 5 6 7 8 9 1 11 12 13 14 15 Depth (m) Figure 28. All turbidity measurements obtained by a bucket-mounted sensor during the descent component of the bucket cycle during the first long-term dredging test on January 3, 28. 73
1 9 Ascending Linear 8 7 y = 13.79x + 137.67 R 2 =.1462 6 5 4 3 2 1 1 2 3 4 5 6 7 8 9 1 11 12 13 14 15 Depth (m) Figure 29. All turbidity measurements obtained by a bucket-mounted sensor during the ascent component of the bucket cycle during the first long-term dredging test on January 3, 28. 74
1 9 HIGH SLACK 4 3.5 8 7 6 5 4 FLOOD EBB 3 2.5 2 1.5 ELEVATION (FT) 3 2 1 1.5 8:: 9:: 1:: 11:: 12:: 13:: 14:: 15:: 16:: 17:: TIME (EST) Figure 3. Turbidity measurements obtained by a bucket-mounted sensor during the second long-term dredging test on January 31, 28. Note two sensors were mounted on opposite sides of bucket: inboard sensor (blue) & outboard sensor (purple). 75
Figure 31. Location of OBS instrument on the outboard side of the bucket. 76
1 9 8 7 Descending Ascending Digging Moving 6 5 4 3 2 1 1 2 3 4 5 6 7 8 9 1 11 12 13 14 15 Depth (m) Figure 32. All turbidity measurements obtained by a bucket-mounted sensor (inboard side) during the second long-term dredging test on January 31, 28. 77
1 9 8 7 Descending Ascending Digging 6 5 4 3 2 1 1 2 3 4 5 6 7 8 9 1 11 12 13 14 15 Depth (m) Figure 33. All turbidity measurements obtained by a bucket-mounted sensor (inboard side) during the second long-term dredging test after removal of all data for dredge advances on January 31, 28. 78
1 9 Descending Linear 8 7 y = -9.165x + 314.64 R 2 =.536 6 5 4 3 2 1 1 2 3 4 5 6 7 8 9 1 11 12 13 14 15 Depth (m) Figure 34. All turbidity measurements obtained by a bucket-mounted sensor (inboard side) during the descent component of the bucket cycle during the second long-term dredging test on January 31, 28. 79
1 9 8 y = 13.131x + 196.39 R 2 =.1357 Ascending Linear 7 6 5 4 3 2 1 1 2 3 4 5 6 7 8 9 1 11 12 13 14 15 Depth (m) Figure 35. All turbidity measurements obtained by a bucket-mounted sensor (inboard side) during the ascent component of the bucket cycle during the second long-term dredging test on January 31, 28. 8
1 9 8 7 Descending Ascending Digging Moving 6 5 4 3 2 1 1 2 3 4 5 6 7 8 9 1 11 12 13 14 15 Depth (m) Figure 36. All turbidity measurements obtained by a bucket-mounted sensor (outboard side) during the second long-term dredging test on January 31, 28. 81
1 9 8 7 Descending Ascending Digging 6 5 4 3 2 1 1 2 3 4 5 6 7 8 9 1 11 12 13 14 15 Depth (m) Figure 37. All turbidity measurements obtained by a bucket-mounted sensor (outboard side) during the second long-term dredging test after removal of all data for dredge advances on January 31, 28. 82
1 9 Descending 8 7 y = -1.144x + 353.3 R 2 =.541 6 5 4 3 2 1 1 2 3 4 5 6 7 8 9 1 11 12 13 14 15 Depth (m) Figure 38. All turbidity measurements obtained by a bucket-mounted sensor (outboard side) during the descent component of the bucket cycle during the second long-term dredging test on January 31, 28. 83
1 9 Ascending Linear 8 7 y = 11.277x + 273.18 R 2 =.794 6 5 4 3 2 1 1 2 3 4 5 6 7 8 9 1 11 12 13 14 15 Depth (m) Figure 39. All turbidity measurements obtained by a bucket-mounted sensor (outboard side) during the ascent component of the bucket cycle during the second long-term dredging test on January 31, 28. 84
1 6 9 8 5 7 6 5 4 3 4 3 2 ELEVATION (FT) 2 1 1 8:: 9:: 1:: 11:: 12:: 13:: 14:: 15:: 16:: 17:: TIME (EST) Figure 4. Turbidity measurements obtained by a bucket-mounted sensor during the third long-term dredging test on February 1, 28. 85
1 9 8 7 Descending Ascending Digging Moving 6 5 4 3 2 1 1 2 3 4 5 6 7 8 9 1 11 12 13 14 15 Depth (m) Figure 41. All turbidity measurements obtained by a bucket-mounted sensor (outboard side) during the third long-term dredging test on February 1, 28. 86
1 9 8 Descending Ascending Digging 7 6 5 4 3 2 1 1 2 3 4 5 6 7 8 9 1 11 12 13 14 15 Depth (m) Figure 42. All turbidity measurements obtained by a bucket-mounted sensor (outboard side) during the third long-term dredging test after removal of data associated with dredge advances on February 1, 28. 87
1 9 Descending Linear 8 7 y = -4.54x + 241.15 R 2 =.129 6 5 4 3 2 1 1 2 3 4 5 6 7 8 9 1 11 12 13 14 15 Depth (m) Figure 43. All turbidity measurements obtained by a bucket-mounted sensor (outboard side) during the descent component of the bucket cycle during the third long-term dredging test on February 1, 28. 88
1 9 Ascending Linear 8 7 y = 6.7463x + 185.23 R 2 =.327 6 5 4 3 2 1 1 2 3 4 5 6 7 8 9 1 11 12 13 14 15 Depth (m) Figure 44. All turbidity measurements obtained by a bucket-mounted sensor (outboard side) during the ascent component of the bucket cycle during the third long-term dredging test on February 1, 28. 89
35 Surface 4 3 HIGH SLACK MidWater Bottom 3.5 Closure 25 2 15 FLOOD EBB FLOOD LOW SLACK HIGH SLACK Tide EBB 3 2.5 2 1.5 ELEVATION (FT) 1 1 5.5 8:: 9:: 1:: 11:: 12:: 13:: 14:: 15:: 16:: 17:: TIME (EST) Figure 45. Turbidity measurements from dredge platform OBS instruments during the first long-term dredging test January 3, 28. 9
5 45 4 35 Surface MidWater Bottom Closure Tide HIGH SLACK EBB 4 3.5 3 3 25 2 FLOOD 2.5 2 1.5 ELEVATION (FT) 15 1 LOW SLACK 1 5.5 7:: 8:: 9:: 1:: 11:: 12:: 13:: 14:: 15:: 16:: 17:: TIME (EST) Figure 46. Turbidity measurements from dredge platform OBS instruments during the second long-term dredging test January 31, 28. 91
5 Surface 6 45 4 MidWater Bottom Closure HIGH SLACK 5 35 Tide FLOOD 4 3 25 2 LOW SLACK 3 ELEVATION (FT) 15 2 1 1 5 7:: 8:: 9:: 1:: 11:: 12:: 13:: 14:: 15:: 16:: 17:: TIME (EST) Figure 47. Turbidity measurements from dredge platform OBS instruments during the third long-term dredging test February 1, 28. 92
35. 33. 31. 29. Descending Ascending Linear (Descending) Linear (Ascending) y = 1.435x + 177.27 R 2 =.9788 27. 25. 23. 21. 19. 17. y = -9.95x + 299.53 R 2 =.759 15. -1m 1-2m 2-3m 3-4m 4-5m 5-6m 6-7m 7-8m 8-9m 9-1m 1-11m Depth Bin 11-12m 12-13m Figure 48. A comparison of trends observed in the descent and ascent components of the bucket cycle based on all turbidity measurements obtained by bucket-mounted sensors during the three long-term dredging tests. 93
45. 4. 35. 3. y = -6.5569x + 323.6 R 2 =.983 Descending - Inboard Descending - Outboard Linear (Descending - Inboard) Linear (Descending - Outboard) 25. 2. 15. y = -9.9114x + 333.91 R 2 =.2496 1. -1m 1-2m 2-3m 3-4m 4-5m 5-6m 6-7m 7-8m 8-9m 9-1m 1-11m Depth Bin 11-12m 12-13m Figure 49. A comparison of synoptic turbidity measurements taken by sensors located on opposite sides of the bucket during the descent component of the bucket cycle during the second long-term dredging test on January 31, 28. 94
55. 5. 45. 4. Ascending - Inboard Ascending - Outboard Linear (Ascending - Inboard) Linear (Ascending - Outboard) y = 12.7x + 263.11 R 2 =.5799 35. 3. 25. y = 15.864x + 184.48 R 2 =.855 2. 15. 1. -1m 1-2m 2-3m 3-4m 4-5m 5-6m 6-7m 7-8m 8-9m 9-1m 1-11m Depth Bin 11-12m 12-13m Figure 5. A comparison of synoptic turbidity measurements taken by sensors located on opposite sides of the bucket during the ascent component of the bucket cycle during the second long-term dredging test on January 31, 28. 95
Figure 51. Identification of dredging process events that occur in tandem with bucket cycles that account for large-scale patterns in the long-term dredging test turbidity data on January 3, 28. 96
Figure 52. Bucket-mounted turbidity sensor turbidity measurements for a 2 bucket cycle sequence that comprised a single dredge advance. Figure based on the same bucket cycle sequence shown in Figure 4 from the long-term test on January 3, 28. 97
1 9 8 7 6 5 4 3 2 1-1 -2-3 -4-5 -6-7 Force (g) Shock - Sum Shock - X Shock - Y Shock - Z 15:19: 15:2: 15:21: 15:22: 15:23: 15:24: 15:25: 15:26: Time (EST) Closure Figure 53. Accelerometer data recorded during long-duration testing on January 31, 28. 98
1 8 6 4 Force (g) 2 1 9 17 25 33 41 49 57 65 73 81 89 97 15 113 121 129 137 145 153 161 169 177 185 193 # Shock - X Axis (g) # # Shock - Y Axis (g) # # Shock - Z Axis (g) # # Shock - Vector Sum (g) # -2-4 -6-8 Chronological Sequence (One unit =.125 seconds) Figure 54. Accelerometer data recorded during long-duration testing on February 1, 28 showing maximum impact forces observed. 99
Lab 14 12 1 8 6 4 2 y =.4341x - 6.1977 R 2 =.9277 5 1 15 2 25 3 35 TSS Concentration (mg/l) Figure 55. Relationship between turbidity and suspended sediment concentration determined from gravimetric analysis of water samples collected at the study site. Water samples were collected during active dregding on February 8, 28 and February 13, 28. 1
% Total measurements 1.% 95.% 9.% 85.% 8.% 75.% 7.% 65.% 6.% 55.% 5.% 45.% 4.% 35.% 3.% 25.% 2.% 15.% 1.% 5.%.% Digging Moving Descending Ascending 5 1 15 2 25 3 35 4 45 5 55 6 65 7 75 8 85 9 95 1 Figure 56. Cumulative percent plots of bucket-mounted turbidity measurements during components of the bucket cycle. 11