US Army Corps Of Engineers
Wilmington District
PHASE II DMMP Study Upper Portion of Wilmington Harbor Eagle Island Management Plan
Volume V Part A Column Sedimentation Tests Report
Wilmington, North Carolina Final Report
May 2001
USACE Wilmington District
Volume V Part A - Column Sedimentation Tests Report Wilmington, N.C.
LIST OF REPORT VOLUMES AND TITLES VOLUME
I PHASE II DMMP Study Upper Portion of Wilmington Harbor Eagle Island Management Plan II III IV V VI VII Embankment Stability Analysis Record of Embankment Stability Analyses Field Investigation Laboratory Tests Primary Consolidation, Secondary Compression, and Desiccation of Dredged Fill (PSDDF) Report Supporting Data
TITLE
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USACE Wilmington District
Volume V Part A - Column Sedimentation Tests Report Wilmington, N.C.
VOLUME V PART A COLUMN SEDIMENTATION TESTS REPORT EAGLE ISLAND CONFINED DISPOSAL SITE WILMINGTON, NORTH CAROLINA TABLE OF CONTENTS
1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 GENERAL PURPOSE OF TEST INFORMATION TO BE DEVELOPED SAMPLE COLLECTION SETUP OF EQUIPMENT PREPARATION FOR TEST TEST PROCEDURE TESTS CONDUCTED TEST RESULTS FOR CST 1A AND 4A TEST RESULTS FOR CST 1, 2, 4 AND 5 SELECTION OF REPRESENTATIVE MATERIAL FOR PSDDF INPUT 1 1 2 2 4 5 5 6 7 7 8
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Volume V Part A - Column Sedimentation Tests Report Wilmington, N.C.
LIST OF PHOTOGRAPHS
PHOTOGRAPH 1 – Shows collection of 5-gallon containers of sediment samples ....................................3 PHOTOGRAPH 2 – Shows collection of 55-gallon poly tanks of river water.............................................3 PHOTOGRAPH 3 – Column Sedimentation Test Set-up.............................................................................4 PHOTOGRAPH 4 – Close-up of Test in Progress........................................................................................6
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Volume V Part A - Column Sedimentation Tests Report Wilmington, N.C.
1.0
GENERAL
This report contains the results of the Column Sedimentation test for the Eagle Island Confined Disposal Facility (CDF) located at Wilmington, North Carolina. Column Sedimentation tests are unlike other, more common tests, in that there is not a published standard (such as an ASTM standard) to guide the testing laboratory. When a published standard is not available, the best available published guidance document relating to the subject is generally used. The reference used for this report is Technical Report DS-78-10 dated December 1978 prepared by the U. S. Army Corps of Engineers, Waterways Experiment Station, Vicksburg, Mississippi.
2.0
PURPOSE OF TEST
The purpose of the column sedimentation test is to evaluate the settling characteristics of sediments to be dredged from a river or a harbor and placed in a CDF for permanent disposal. The information to be determined from the test is as follows: 1. the initial void ratio at the end of sedimentation, 2. the length of time required for the solids to settle out, and 3. the time rate at which the turbidity water improves. The test is intended to model by use of a laboratory simulation the process that occurs in the field during dredging operations. During dredging operations, the sediments are removed from the bottom of the river by the suction of a hydraulic dredge and place in a CDF. In the process, water is added to the sediments to create a fluid that is pumpable and contains approximately 145 grams per liter of solids. This slurry is transported by pipeline to the CDF where it is discharged. The dredging process usually runs until a predetermined volume of sediment is removed or until a specified date associated with a contractual requirement is reached. As the dredged material is retained in the CDF, the solids/water interface forms, the solids begin to settle, and the quality of the water above the solids slowly improves. When the water meets a specified quality standard as determined by onsite turbidity testing, it is discharged back into the river. Eventually, all of the water is decanted from the CDF, the surface of the mud is exposed, and the process of drying due to sun and wind starts. Eventually, the mud in the CDF is dried, self weight consolidation and desiccation consolidation occur, and the CDF is ready for the next layer of sediments.
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USACE Wilmington District
Volume V Part A - Column Sedimentation Tests Report Wilmington, N.C.
3.0
INFORMATION TO BE DEVELOPED
The following relationships are developed from the column sedimentation tests: 1. The time rate at which the solids settle from the slurry; 2. The void ratio of the mud at the completion of sedimentation; 3. The time rate at which the water clarifies. The following additional tests are performed to assist in the identification and classification of the dredged material: 1. grain size analysis, 2. Atterberg limits, 3. natural moisture content, 4. specific gravity, and 5. water salinity, pH and turbidity.
4.0
SAMPLE COLLECTION
Representative samples of the bottom sediments and water from the Cape Fear River and Wilmington Harbor were gathered on 28 July 2000 for conducting the tests. The sediments were collected using a Ponar sampler lowered from a boat. Three five-gallon pails of sediments were collected to provide sufficient sample for one column sedimentation test. Photograph 1 shows the samples in the storage area awaiting testing. In addition, one 55 gallon barrel of river water was collected for each sample set. Photograph 2 shows the barrels of river water in the storage area awaiting use.
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USACE Wilmington District
Volume V Part A - Column Sedimentation Tests Report Wilmington, N.C.
PHOTOGRAPH 1 – Shows collection of 5-gallon containers of sediment samples
PHOTOGRAPH 2 – Shows collection of 55-gallon poly tanks of river water.
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Volume V Part A - Column Sedimentation Tests Report Wilmington, N.C.
5.0
SETUP OF EQUIPMENT
The column sedimentation test is intended to model the sedimentation process as it actually occurs in the CDF during dredging operations. The column used is an eight-inch in diameter, eight foot high Plexiglas tube constructed as detailed in DS-78-10. Because of the length of time required for the tests and the limited number of columns available in the southeast, it was decided to use two separate laboratories to conduct the tests Two column sedimentation devices were set up in the URS laboratory in Atlanta, Georgia and two were set up in the laboratory in Charleston, South Carolina. The setup of the two columns in the Atlanta laboratory is shown in Photograph 3.
PHOTOGRAPH 3 – Column Sedimentation Test Set-up
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Volume V Part A - Column Sedimentation Tests Report Wilmington, N.C.
6.0
PREPARATION FOR TEST
The testing process began by analyzing the river water to determine the pH, salinity and turbidity. The results of these tests are reported in the tables at the end of this report. This information indicated that the river water was slightly saline and that zone settlement was likely. The sediments were tested to determine grain size distribution, Atterberg limits, and natural moisture content. The results of the tests are reported in the tables at the end of his report. From the natural moisture content, the amount of water needed to be added to make a slurry of 145 grams/liter was made. Those calculations are shown at the end of this report.
7.0
TEST PROCEDURE
The following test procedure was used for each test: 1. The amount of sediment needed to prepare the correct amount of sample was weighed. The sediments were placed in the mixing barrel. 2. The appropriate amount of river water was weighed and added to the barrel. 3. The sediments and water were mixed until homogeneous. 4. The slurry was then pumped into the column using diffused, compressed air to insure that premature sedimentation did not occur. 5. When the slurry depth in the column reached approximately six feet, pumping was halted and the compressed air being fed in was turned off. 6. When the turbulence in the column subsided, the initial column height was marked and recorded 7. At the beginning of the test, the column was closely observed to determine that the solids interface indicating zone settling was developing. 8. For the duration of the test, the depth of the solids interface as a function of time was measured. A close up of the solid/water interface can be seen in Photograph 4. 9. At the end of the test, the overall height change of the column was measured. 10. At certain times during the test, water quality readings were taken using an Horiba multi meter. The tests measured pH, salinity and turbidity. 11. At the completion of each test, the data was submitted for report preparation.
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USACE Wilmington District
Volume V Part A - Column Sedimentation Tests Report Wilmington, N.C.
8.0
TESTS CONDUCTED
Four column sedimentation tests were set up to run on the four columns in the two laboratories. The tests were run on samples CST 1, CST 2, CST 4, and CST 5. The soil data indicated that the sediments were all fine-grained material and that sedimentation times would likely be relatively long. As indicated in the attached test results, this did indeed occur, and the tests had to run for as long as 28 days in order to get full results. Photograph 4 shows a close up of a test in progress.
PHOTOGRAPH 4 – Close-up of Test in Progress
After the initial four tests were run, two additional tests were set up and initiated. These two tests were as follows:
•
CST 1 was set up to model what would happen if the dredged slurry solids concentration was reduced from 145 grams/liter to 72 grams per/liter or approximately one-half the solids concentration of the initial test. This was accomplished by adding water to the slurry and reloading the column. The reconstituted CST 1 was renamed CST 1a. CST 4 was set up to model what would happen if the salinity of the slurry was increased from the approximately 1% as tested to the salinity of seawater (approximately 3.5%). This was accomplished by adding dried sea salt to the slurry in the column. CST 4 was then renamed CST 4a.
•
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Volume V Part A - Column Sedimentation Tests Report Wilmington, N.C.
9.0
TEST RESULTS FOR CST 1A AND 4A
The initial solids concentration in the slurry in CST 1a was approximately one-half that of CST 1 at the initiation of the test. As the test progressed, the solids settled out and formed an interface at approximately one half the depth of the previous test. Sedimentation occurred relatively quickly, and the interface could be detected (though only approximately) in about two days. However, the turbidity of the water was too high to be measured for quite some time. It was concluded from height/volume measurements that the void ratio of the solids forming at the bottom of the column would be roughly the same for the 72-grams/liter slurry as for the 145-grams/liter slurry if the sedimentation was allowed to continue to completion. It was also concluded that water quality improvement would likely take as long for the 72-grams/liter slurry as it would for the 145-grams/liter slurry. The tests were terminated due to time constraints once this qualitative evaluation was made. The percent salt increase for CST 4a had no apparent affect on either the sedimentation time for the solids or the water quality improvement compared to over CST 4. The data points plotted for CST 4a fell on the same curves as those prepared for CST 4. This established that seawater as opposed to river water would not likely change the characteristics of sedimentation or water quality improvement, and the tests were terminated. It was found that the sediments were saltier that the river water and that any dredged slurry could be expected to be more saline than river water alone. This would have little impact on Total Suspended Solids (TSS) but could have impact on Total Dissolved Solids (TDS) and salinity if that should ever become an issue. The test results for CST 1a and CST 4a were intended to be qualitative to see if trends could be detected. Thus only the observations discussed above are presented in this report.
10.0 TEST RESULTS FOR CST 1, 2, 4 AND 5
The test results for CST 1, 2, 3, and 5 are presented in the following tables and figures listed below 1. Table 1 River Water Sample Data Collected 28 July 2000 2. Table 2 Water Quality Data Sample CST 1 3. Table 3 Water Quality Data Sample CST 4 4. Table 4 Soil Test Results 5. Table 5 Sediment Sample %Water Content and Void Ratio Calculations 6. Figure 1 General Relationship Void Ratio vs. Column Height 7. Figure 2 Void Ratio vs. Solids Content
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Volume V Part A - Column Sedimentation Tests Report Wilmington, N.C.
8. Figure 3 Water Quality Improvement CST 1 9. Figure 4 Water-Sediment Interface vs. Time CST 1 10. Figure 5 Water Quality Improvement CST 2 11. Figure 6 Water-Sediment Interface vs. Time CST 2 12. Figure 7 Water Quality Improvement CST 4 13. Figure 8 Water-Sediment Interface vs. Time CST 4 14. Figure 9 Water Quality Improvement CST 5 15. Figure 10 Water-Sediment Interface vs. Time CST 5 16. Table 6 Water Quality Data 17. Table 7 Water Quality Interface vs. Time Data 18. Table 8 Sample Calculations 19. Table 9 Volume Calculations
11.0 SELECTION OF REPRESENTATIVE MATERIAL FOR PSDDF INPUT
The test results identified the sediments to be fine grained with high in situ void ratios. The Unified Soil Classification found all the sediments to be a highly compressible clay (CH). The upper limit of the estimated void ratio after completion of sedimentation was determined to be approximately 10.5. This value was derived from the grab samples and verified through the column sedimentation tests. The lower limit of the void ratio was approximately 7.0. This value was not tested with the column sedimentation test but estimated from the sample data. As a result of the tests, the recommended criteria for soil selection to model the sediments for the PSDDF analysis is a CH material with an initial void ratio of 10.5.
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USACE Wilmington District
Volume V Part A - Column Sedimentation Tests Report Wilmington, N.C.
Volume V Part A Column Sedimentation Tests Report
TABLES
Eagle Island Dredge Material Management Plan
Water Quality Table 1
River Water Sample Data Collected 28 July 2000 Sample Number pH Turbidity (ntu's) Salinity (%salt) CST-1 7.75 74 0.88 CST-4 7.65 31 0.81 CST-6 7.62 9 0.70 CST-7 7.64 64 0.85 CST-8 7.61 41 0.85 CST-9 7.64 31 0.88 CST-11 7.61 12 0.67
Water Quality Table 2
Date 21-Sep-00 22-Sep-00 23-Sep-00 24-Sep-00 02-Oct-00 10-Oct-00 Water Quality Data Column 1 Sample CST-1 Hour pH Turbidity (ntu's) Salinity (%salt) 224 7.66 81 1.20 251 8.13 64 1.20 275 7.85 55 1.18 300 7.83 49 1.17 484 7.28 27 1.24 679 7.53 20 1.28
Water Quality Table 3
Date 21-Sep-00 22-Sep-00 23-Sep-00 24-Sep-00 02-Oct-00 10-Oct-00 Water Quality Data Column 1 Sample CST-4 Hour pH Turbidity (ntu's) Salinity (%salt) 223 7.59 56 1.04 250 7.96 47 1.05 274 7.81 41 1.03 299 7.81 37 1.04 483 7.5 14 1.06 678 7.52 10 1.07
Note: The above tables were prepared from data gathered to record water quality by measuring pH, turbidity and salinity. Representative samples were selected for the cases shown. Not all samples taken were tested.
Eagle Island Dredge Material Management Plan
Table 4 Soil Test Results
GRAIN SIZE Sample No. % PASSING #200 SIEVE % CLAY CST-1 96.3 80.9 CST-2 97.2 57.9 CST-3 94.7 36.1 CST-4 95.4 24.8 CST-5 70.3 26.1 CST-6 91.4 30.1 CST-7 86.6 32.0 CST-8 87.5 29.7 CST-9 66.3 32.5 CST-11 77.5 41.0 ATTERBERG LIMITS % SILT 15.4 39.3 58.6 70.6 44.2 61.3 54.6 57.8 33.8 36.5 NATURAL MOISTURE 404.7 363.6 360.4 390.5 296.8 339.4 342.1 288 215.5 245.6 LL 212 196 198 182 142 190 195 172 118 154 PL 51 49 48 49 35 49 46 44 33 42 PI 161 147 150 133 107 141 149 128 85 112 CLASSIFICATION USCS* CH CH CH CH CH CH CH CH CH CH AASHTO A-7-5 A-7-6 A-7-7 A-7-8 A-7-9 A-7-10 A-7-11 A-7-12 A-7-13 A-7-14
Table 5 Sediment Sample % water content and void ratio calculations
Column A Sample No. CST-1 CST-1A CST-1B CST-4A CST-4B CST-4C CST-6A CST-6B CST-6C CST-7A CST-7B CST-8A CST-8B CST-8C CST-9A CST-9B CST-11A CST-11B Column B Pan 91A 230 45A 272 90 225 21A 235 16A 266 259 25A 245 24A 279 8A 62A 280 Column C Column D Column E Total Wet Wet Weight Weight of Tare of Sample Sample (D-C) and Tare 90.81 470.57 379.76 87.32 443.86 356.54 86.59 262.43 175.84 83.14 87.84 80.42 85.45 91.07 86.04 85.37 80.48 86.53 79.88 87.03 85.09 92.19 90.69 83.28 415.98 407.50 422.85 440.24 447.76 434.07 458.24 483.57 485.85 442.43 430.43 420.93 444.02 447.17 535.41 332.84 319.66 342.43 354.79 356.69 348.03 372.87 403.09 399.32 362.55 343.40 335.84 351.83 356.48 452.13 Column F Column G Column H Column I Column J Column K Oven Dry Use the Ratio Weight of Dry Weight Sample Weight of Water of Sample Water/Soli following void ratio Sample ratio ds (F-C) (D-E) and Tare 77.76 3.88 168.57 302.00 73.23 3.87 3.87 10.4 160.55 283.31 78.78 1.23 165.37 97.06 157.38 159.20 160.89 163.81 174.05 166.39 168.64 167.35 198.82 175.90 164.92 170.92 198.66 212.54 212.41 258.60 248.30 261.96 276.43 273.71 267.68 289.60 316.22 287.03 266.53 265.51 250.01 245.36 234.63 323.00 74.24 71.36 80.47 78.36 82.98 80.35 83.27 86.87 112.29 96.02 77.89 85.83 106.47 121.85 129.13 3.48 3.48 3.26 3.53 3.30 3.33 3.48 3.64 2.56 2.78 3.41 2.91 2.30 1.93 2.50
3.41
9.2
3.39
9.1
3.56
9.6
2.91
7.9
2.61
7.0
2.21
6.0
Note: Some consolidation occurred during transport as evidenced by free wqater on the surface of the sample. The surface water was decanted before shipping.
Eagle Island Dredge Material Management Plan
CST-1 Time Turbidity ( hours ) ( ntu ) 224 81 251 64 275 55 300 49 484 27 679 20
Table 6 - Water Quality Data CST-2 CST-4 CST-5 Time Turbidity Time Turbidity Time Turbidity ( hours ) ( ntu ) ( hours ) ( ntu ) ( hours ) ( ntu ) 41 111 223 56 27 195 69 144 250 47 53.5 129 94.5 68.7 274 41 75.5 105 119.5 56.8 299 37 99.5 89 145 48.2 483 14 122.5 56.7 161 44.3 678 10 146 38.9 197 63.8 175 44.6 218 51.8 198.5 37.2 240 43.2 234.5 34.5 265 43.1 287 27.5 329.5 24.3 362.5 22.4 386.5 28.5 410 30.2 435 31.7 459 28.5 483 27.6
Eagle Island Dredge Material Management Plan
Table 7 - Water/Sediment Interface vs Time Data CST 1 Height from Top in (in) 0 0.6 1.3 1.5 2.0 2.6 3.1 3.9 4.7 5.2 5.9 6.3 7.1 7.5 7.9 8.2 8.5 10.7 12.0 CST 2 Height from Top in (in) 0.02 0.02 0.12 0.12 0.12 0.12 0.22 0.32 0.42 0.92 2.02 2.42 2.72 3.12 3.82 4.72 5.22 6.72 7.22 7.32 7.72 8.32 8.92 10.42 11.22 12.22 13.02 13.72 14.22 14.72 15.12 15.42 16.22 16.72 17.02 17.62 18.02 18.42 19.02 CST 4 CST 5 Height from Time Height from Top in (in) ( hour ) Top in (in) 0 1 0.02 0.5 1.5 0.22 1.2 2 0.32 1.5 3 0.52 2.0 4 0.82 2.9 5 1.02 3.8 6 1.32 4.9 8 1.82 6.0 12 2.02 6.7 18 2.42 7.6 27 4.02 7.9 43 5.42 8.9 53.5 6.22 9.4 67 7.42 9.8 99.5 10.22 10.4 122.5 11.42 10.8 146 12.02 13.8 175 13.32 15.9 198.5 14.22 234.5 15.52 261 16.62 284.5 17.52 306.5 18.22
Time ( hour ) 10 21 33 36 45 58 70 90 114 135 164 179 212 234 261 285 310 494 689
Time ( hour ) 0 0.5 1 1.5 2 3 4 5 6 8 16 19 22 26 30 41 44 50 65 69 74 94.5 119.5 145 161 197 218 240 265 286.5 310.5 329.5 362.5 386.5 410 435 459 483 507
Time ( hour ) 11 21 33 37 45 58 70 90 114 135 164 179 212 234 261 285 310 494 689
Eagle Island Dredge Material Management Plan
Table 8 - Sample Calculations
From Sheet 1 CST-1 91A 90.81 470.57 379.76 CST-1A 230 87.32 443.86 356.54 CST-1B 45A 86.59 262.43 175.84 Conclusion: Use 3.88 as the ratio. Corresponds to avoid ratio of 10.4 Volume for 6.5 feet of slurry: Volume = Column Area (ft) x Column Height (ft) Height 6.5 feet Diameter 7.5 inches = 0.625 feet pi = 3.14 Volume = 1.993164 cubic feet Provide a 20 % overage Volume = 2.391797 Cubic feet Conversion Factor = 7.481 gallons per cubic foot Volume = Volume in gallons = 17.893032 or 2.4 cubic feet 17.89303 168.57 160.55 165.37 302.00 283.31 97.06 77.76 73.23 78.78 3.88 3.87 1.23
Volume = Volume = Check
0.306641 feet/foot of height 1.993164 62.42895 lbs/ft3
Prepare 18 gallons of slurry
Using 145 grams per liter as the starting point for solids Assume a specific gravity of 2.7 Assume a water content of 3.87 Wsolids / Wwater= .145 Wsolids= .145 Wwater Density of water = Dw Density of solids =Ds SG water = 1 SG solids = 2.7 62.4 168.48
Volume 1 cu ft
V water
V solids 1 = Volume of solids + Volume of water 1 = Vs + Vw 1 = Wsolids/Ds +Wwater/Dw 1 = (.145Wwater)/Ds +Wwater/DW 1 = (.145Wwater)/168.48 +Wwater/62.4 1=Wwater(.145/168.48 + 1/62.4) Wwater = 1/(.145/168.48 + 1/62.4) Wwater = 59.21968 Check Vwater = Vwater = 0.949033 Vsolids = Vsolids = 0.050967 Total Wsolids = 8.523248 Wtotal = 67.74293 Ratio =
0.949033 0.050967 1 0.144 OK
Eagle Island Dredge Material Management Plan
Table 9 - Volume Calculations
Based on 18 gallons of slurry or 2.4 cubic feet of sludge Total Weight of Water Required = 2.4x59.2 = 142.08 Total Weight of Solids Required = 2.4x8.58 = 20.59 Total Weight 142.08 + 20.59 = 162.67 Sample Weight of Solids Total Weight of Total Weight of to Weight of Water Water Solids Ratio CST-1 CST-1A 3.87 142.08 20.59 CST-1B CST-4A CST-4B CST-4C CST-6A CST-6B CST-6C CST-7A CST-7B CST-8A CST-8B CST-8C CST-9A CST-9B CST-11A CST-11B
Pounds of Weight of Water to be Check sludge Required Water in Added Column Sludge 100.3 79.7 62.4 162.7
3.41
142.08
20.59
90.8
70.2
71.9
162.7
3.39
142.08
20.59
90.4
69.8
72.3
162.7
3.56
142.08
20.59
93.9
73.3
68.8
162.7
2.91
142.08
20.59
80.5
59.9
82.2
162.7
2.61
142.08
20.59
74.3
53.7
88.3
162.7
2.21
142.08
20.59
66.1
45.5
96.6
162.7
USACE Wilmington District
Volume V Part A - Column Sedimentation Tests Report Wilmington, N.C.
Volume V Part A Column Sedimentation Tests Report
FIGURES
Figure 1 - General Relationship (Void Ratio vs. Column Height)
20 Void Ratio 15 10 5 3.5 4 4.5 5 5.5 6 6.5 7 Column Height (feet)
Figure 2 - Void Ratio vs. Solids Content
20.0 18.0 16.0 14.0 12.0 10.0 8.0 6.0 4.0 2.0 0.0 0 0.1 0.2 0.3 kilograms / liter 0.4 0.5 0.6
Void Ratio
Figure 3 - Water Quality Improvement CST 1
90 80 70 60 50 40 30 20 10 0 0 100 200 300 400 Time (hours)
Turbidity (ntu's)
0.07
500
600
700
800
Figure 4 - Water-Sediment Interface vs Time CST 1
0 2 4 6 8 10 12 14 0 100 200 300 400 500 600 700 800 Time (hours) Water-Sediment Interface Height from Top (inches)
Figure 5 - Water Quality Improvement CST 2
160 140 120 100 80 60 40 20 0 0 100 200 300 Time (hours) 400 500 600
Turbidity (ntu's)
Figure 6 - Water-Sediment Interface vs Time CST 2
Water-Sediment Interface height from Top (inches)
0 2 4 6 8 10 12 14 16 18 20 0 100 200 300 400 500 600
Time (hours)
Figure 7 - Water Quality Improvement CST-4
60 Turbidity (ntu's) 50 40 30 20 10 0 0 100 200 300 400 Time (hours) 500 600 700 800
Figure 8 - Water-Sediment Interface vs Time CST-4 Results
Water-Sediment Interface Height from Top (inches)
0 2 4 6 8 10 12 14 16 18 0 100 200 300 400 500 600 700 800 Time (hours)
Figure 9 - Water Quality Improvement CST 5
250 Turbidity (ntu's) 200 150 100 50 0 0 50 100 150 200 250 Time (hours)
Figure 10 - Water-Sediment Interface vs Time CST 5
Water-Sediment Interface height from Top (inches)
0 2 4 6 8 10 12 14 16 18 20 0 100 200 300 Time (hours) 400 500 600