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evaluation of dredged material proposed for discharge in waters of

1. E ede eque e dace C 17 C2 6 General Instructions for Running the C 21 C2 6 1 Target Hardware Environment 21 2 6 2 Installation and Starting C 22 C2 6 3 2 7 C2 8 C2 8 1 C2 8 1 1 C2 8 1 1 1 C2 8 1 1 2 C2 8 1 1 3 C2 8 1 1 4 C2 8 1 1 5 C2 8 1 1 6 C2 8 1 1 7 C2 8 1 2 C2 8 1 2 1 C2 8 1 2 2 C2 8 1 2 3 C2 8 2 2 8 2 1 2 8 2 1 1 2 8 2 1 2 2 8 2 1 3 2 8 2 1 4 2 8 2 1 5 2 8 2 1 6 2 8 2 1 7 2 8 2 2 C2 8 2 2 1 C2 8 2 2 2 C2 8 2 2 3 C3 0 C4 0 C4 1 4 2 4 3 4 4 C5 0 C6 0 C6 1 C6 2 C7 0 il User sh ys BERS DR BER ae ake Steps in Using the Model STFATE Application Examples Split hull Barge or Scow Example Entering STFATE and the Input Data File Selection Menu Site Description Data Velocity uuu See Se a Eton Res Input Execution and Output Keys Material Description Disposal Operation Data Coelficients Dp A Oe Ba ees CN Saving Input Data Menu Descri
2. where volume of site water unit time required for dilution cfs V rate of effluent discharge cfs C concentration of the contaminant in the effluent in ug L background concentration of the contaminant in the disposal site water in ug L Cwo applicable water quality standard for the contaminant in ug L It is assumed that the mixing zone associated with an effluent discharge will resemble the shape in Figure C 19 Therefore once the required volume per unit time has been calculated the next step is to determine the dimensions of the mixing zone The required volume per unit time can also be expressed as V Ld V where V required volume of water per unit time cfs L width of mixing zone at time t ft d depth ft V velocity of water at disposal site ft sec 74 x r ic gt AN FRONTAL PROJECTED SURFACE AREA YOLUME PER UNIT TIME L 2 1 x V LdV Figure C 19 Projected Surface Area and Volume Equations for CDF Effluent Discharge with Prevailing Current Since the depth and water velocity are known or can be measured the width of the front edge of the mixing zone can be calculated as a N Based on Brooks 1960 and Johnson and Boyd 1975 the time required for the front edge of the mixing zone to spread laterally to the required width L can be computed from 75 t 0 094 123 0
3. Example Mixing Zone Calculation FASTTABS MODELING SYSTEM FOR EVALUATION OF HYDRODYNAMIC TRANSPORT DILUTION VOLUME METHOD CDF EFFLUENT DISCHARGES Approach enge ER ERREUR ES Sample Computations REFERENCES ks GGA Geeta a wee a aS EU OE ERR eet iii LIST OF TABLES Page No Table C 1 Summary of Discharge Types Hydrodynamic Conditions and Applicable Models and Methods for Evaluation of Initial Mixing C 9 Table C 2 STFATE Model Input Parameters C 18 Table C 3 STFATE Input Variables for Section 404 b 1 Regulatory Analysis of Navigable Waters Using a Scow Barge Disposal 31 Table 4 STFATE Input Variables for Section 404 b 1 Regulatory Analysis of Navigable Waters Using a Multiple bin Hopper Dredge Disposal C 46 Figure C 1 Figure C 2 Figure C 3 Figure C 4 Figure C 5 Figure C 6 Figure C 7 Figure C 8 Figure C 9 Figure C 10 Figure C 11 Figure C 12 Figure C 13 Figure C 14 Figure C 15 Figure C 16 Figure C 17 Figure C 18 Figure C 19 iv LIST OF FIGURES Page No Illustration of Placement Processes C 11 Velocity Profile Available for Use in PC Model C 16 Menu Tree for STFATE Model C 23 5 Input Menus C 24 Schematic of Example Disposal Site for Barge Disposal C 34 X direction Velocity Profile for Barge
4. 122 548 485 427 376 5334 292 258 228 202 STANDARD IS V 0 0 180 STANDARD IS V 0 0 160 STANDARD IS V 798 23339 294 259 228 22104 SEA 156 138 123 109 STANDARD IS V 0 0 971 STANDARD IS V gt 1 ONU 1 CO OO OY CO Q Q gt Ps lt J O IS AO HS 02 E 0 0 E 0 E 0 EO E 0 E 0 E 0 EO IOLATED OUTS E 0 IOLATED OUTS EO IOLATED OUTS 01 E 00 E 00 E 00 E 00 E 00 E 00 00 E 00 E 00 E 00 E 00 1500 750 1500 750 1650 750 1800 750 1950 750 2100 750 2250 750 2400 750 2550 750 2700 750 DE THE MIXING 2850 750 3000 56 1500 15 00 1650 1800 1950 2100 2250 2400 2550 2700 2850 3000 750 DE THE MIXING ZONE 1 00 HOURS E 0 500 750 E 0 50 0 750 E 0 650 750 E 0 800 750 E 0 950 750 0 2100 750 E 0 2250 150 E 0 2400 750 0 2550 750 E 0 2700 750 E 0 2850 750 IOLATED OUTSIDE THE MIXING E 00 3000 750 IOLATED OUTSIDE THE MIXING 750 750 750 750 750 750 150 750 750 750 750 750 ZONE 0 8 ZONE 0 9 0 481 lou 87 239 29
5. 46 18 234 293 380 984 414E 25 305E 05 559E 04 480E 03 240E 02 794E 02 95E 01 386E 01 649E 01 627 00 HOURS 62E 01 HOURS 60E 01 E 25 E 05 E 04 E 03 E 02 E 02 E 01 E 01 E 01 E 00 E 00 ZONE AT 0 92 HOURS 0 971 E 00 ZONE AT 1 00 HOURS 560 412 154 649 325 107 264 522 878 848 220 217 STANDARD WAS VIOLATED OUTSIDE THE MIXING ZONE DURING T Figure C 14 Selected Output for Hopper Dredge Disposal concluded E 26 E 06 E 05 E 04 E 03 E 02 E 02 E 02 E 02 E 01 E 00 E 00 HE SIMULATION 57 indicates the 0 4 toxicity standard entered in the input phase is violated at depths of 0 10 20 and 30 ft but it is not violated at 39 and 40 ft within the 3600 seconds Thus the statement at the bottom of Figure C 14 says the toxicity standard is violated outside the mixing zone C2 8 2 2 3 Hopper Maximum Concentration and Contour Graphs From the STFATE Activity Selection Menu F4 Generate Graphics is selected to receive the STFATE Graphics File Selection Menu First the name of the data file used during execution is entered after selecting Fl Enter name of data file used during execution Next the F4 Generate graphics with selected file is pressed to receive the STFATE Graphics Generation Menu The first option is to select Fl Maximum concentrations versus time which brings a screen up to select where a
6. INITIAL MIXING COMPUTATIONS RESULTS FOR SILT MAX CONC ABOVE MAX CONC ABOVE BACKGROUND BACKGROUND OUTSIDE TIME DEPTH ON ENTIRE GRID X LOC Z LOC MIXING ZONE HR FT MG L FT FT MG L 0 25 20 0 0 493E 03 1800 750 0 504 04 0 50 20 0 0 456E 03 2100 750 0 146 01 0 75 20 0 0 311 03 2550 750 0 507 00 00 20 0 0 217E 03 3000 750 0 217E 03 0 25 39 0 0 137E 04 1650 750 0 162 04 0 50 39 0 0 751E 02 2100 750 0 240 02 0 75 39 0 0 511E 02 2550 750 0 834E 01 00 39 0 0 357E 02 3000 750 0 357E 02 INITIAL MIXING COMPUTATIONS RESULTS FOR CLAY MAX CONC ABOVE MAX CONC ABOVE BACKGROUND BACKGROUND OUTSIDE TIME DEPTH ON ENTIRE GRID X LOC 2 MIXING ZONE HR FT MG L FT FT MG L 0 25 20 0 0 477E 03 1800 750 0 476 04 0 50 20 0 0 299E 03 2100 750 0 215E 01 0 75 20 0 0 209E 03 2550 750 0 516E 00 00 20 0 0 147E 03 3000 750 0 147E 03 0 25 39 0 0 244E 03 1500 750 0 214E 04 0 50 39 0 0 492E 02 2100 750 0 353E 02 0 75 39 0 0 343E 02 2550 750 0 849 01 00 39 0 0 241E 02 3000 750 0 241E 02 Figure C 14 Selected Output for Hopper Dredge Disposal INITIAL MIXING COMPUTATIONS RESULTS FOR FLUID MAX CONC ABOVE MAX CONC ABOVE BACKGROUND BACKGROUND OUTSIDE TIME DEPTH ON ENTIRE GRID X LOC Z LOC MIXING ZONE HR FT PERCENT FT FT PERCENT 0 08 20 0 0 203E 0 1350 750 0 823 26 0 17 20 0 0 548 0 1500 750 0 305 05 0 25 20 0 0 485 0 1650 750 0 559E 04 0 33 20 0 0 427 0
7. No models have been identified that are suitable for a broad range of mixing zone conditions and there are no readily available models suitable for modeling the first few hundred metres downstream from the discharge point This is because the overwhelming majority of computer models are concerned with far field solutions where concentrations can be adequately described by a two dimensional or a one dimensional model and the initial characteristics of the discharge are relatively unimportant These models are generally inadequate in the immediate vicinity of a discharge where a three dimensional description of concentrations is often necessary and where the initial characteris tics of the discharge can be highly significant Within the first few hundred metres of the discharge there are several different processes that may be significant so a general model must be able to estimate each of the processes for example momentum buoyancy dispersion and to identify the zones within which the processes are dominant A general mixing zone model must therefore be a series of submodels each of which can handle a zone that is dominated by one of the principal mixing processes sub models must be capable of determining the limits of their applicable zones and passing concentration values at these limits on to other submodels so that the entire mixing zone may be estimated The following tabulation presents a summary of the steady state physical process
8. 01 02 03 06 10 14 19 23 26 28 26 23 19 14 10 06 03 02 0 0 0 0 0 0 230000 0 0 01 01 02 03 03 203 03 03 02 01 01 0 00 0 0 0 240000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Orr 20 0 70 0 0 250000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 260000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 270000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 280000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 290000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 300000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 31 OO00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 SUMMARY OF CONCENTRATIONS FOR CLAY MAX CONC ABOVE BACKGROUND TIME DEPTH ONENTIREGRID Z LOC HR MG L FT FT 0 25 15 0 0 306E 03 1500 750 0 50 15 0 0 473E 03 1950 750 075 150 0 318 03 2400 750 1 00 150 0 293 03 2400 750 0 25 390 0 430 04 1350 750 0 50 290 0 815 03 1650 750 0 75 390 0 427 03 1950 750 1 00 390 0 544 02 2400 750 SUMMARY OF CONCENTRATIONS FOR LEAD MAX CONC ABOVE BACKGROUND MAX CONC TIME DEPTH ON ENTIRE GRID GRID X LOC Z LOC HR MG L MG L FT FT 0 08 15 0 0 286E 12 0 200E 03 1200 750 017 15 0 0 212E 02 0 232E 02 1350 750 0 25 15 0 0 604E 02 0 624E 02 1500 750 0 33 15 0 0 511E 02
9. 2 where u w input ambient velocities fps At long term time step sec In addition to the advection or transport of the cloud the cloud grows both horizontally and vertically as a result of turbulent diffusion horizontal diffusion is based upon the commonly assumed four thirds power law Therefore the diffusion coefficient K up to a maximum value of 100 ft s is given as K AL 3 XZ hew where is an input dissipation parameter and L is set equal to four standard deviations As illustrated in Figure 2 4 of Brandsma and Divoky 1976 a value of 100 ft sec for the horizontal diffusion coefficient corresponds to a length scale of 10 10 feet With the computational grid cell typically being on the order of 100 500 ft a length scale greater than 1 000 ft would normally be associated with mean flow rather than turbulence Thus restricting the diffusion coefficient to less than 100 ft sec is reasonable 14 Horizontal growth is achieved by employing the Fickian expression 0 K 0 4 where a standard deviation t time since formation of the cloud From Equation 4 dc K 5 dt X Z X Z and thus OLOR 6 where O at the current time step At X O at the previous time step At In a similar manner the vertical growth is written as gt At 7 where K is a function of the stratification including t
10. Disposal Operation Selection Menu Menu for Selection of a Contaminant for Modeling F1 Disposal from a Multiple Bin Hopper Dredge F2 Disposal from a Split Hull Barge or Scow Esc Stop input and return to STFATE Activity Menu F1 Build or edit bulk sediment quality data F2 Build or edit elutriate water quality data F3 Compute bulk sediment dilutions F4 Compute elutriate dilutions F5 Save bulk sediment and elutriate water quality data Esc Quit STFATE Input Selection Menu F1 Site Description F2 Velocity Data Input Execution and Output Keys F4 Material Description Data F5 Disposal Operation Data F6 Coefficients Default Values F7 Saving Input Data Menu Esc Stop input and return to STFATE Activity Menu STFATE Contaminant Data File Saving Menu F1 Enter name of file to be saved F2 Enter DOS path for data file Optional F3 Display directory of input data files FA Save data in or to the active data file Esc Return to STFATE Evaluation Selection Menu STFATE Input File Saving Menu F1 Enter name of file to be saved F2 Enter DOS path for data file Optional F3 Display directory of input data files F4 Save data in or to the active file Esc Return to STFATE Input Selection Menu Figure C 4 STFATE Input Menus 25 Starting Change the directory to make directory containing the STFATE module the default
11. STFATE Input Selection Menu C2 8 1 1 4 Material Description Data The material description data are entered after choosing the F4 Material Description Data from the STFATE Input Selection Menu Next the first material description data entry screen appears and requests information on the number of layers 1 to 6 of material in the barge and the total volume of each layer In the example the number of layers is 2 and their volumes 2000 and 1000 respectively Press PAGE DOWN to get the next screen which provides for specifying the barge velocity in terms of x and z direction components for each layer The barge velocity is assumed to be constant at 6 ft s in the x direction After pressing PAGE DOWN material separation in the barge is selected as YES for this example that is the concentration of solids vary from layer to layer in the discharges from the barge Also requested is the number of solid fractions 1 to 4 in the 36 material such as clumps gravel sand silt or clay this example uses 3 solid fractions next screen inputs the physical characteristics of the solids fractions which are entered in the highlighted boxes on the screen Typical values and their ranges are shown at the top of the screen For the example the input values are shown in Table C 3 Press PAGE DOWN to get the next screen which asks if the adjustment of the entrainment and drag coefficients based on the moisture content is desire
12. A 1977 Convective dispersion in perennial streams J Environ Engineer Am Soc Civil Engineers 103 321 340 Schroeder P R and M R Palermo 1990 Automated dredging and disposal alternatives management system User s Guide Technical Note EEDP 06 12 U S Army Engineer Waterways Experiment Station Vicksburg MS Stefan H and J S Gulliver 1978 Effluent mixing zone in a shallow river J Environ Engineer Am Soc Civil Engineers 104 199 213 Thomas W A and McAnally W H Jr 1990 User s Manual for the Generalized Computer Program System Open Channel Flow and Sedimentation TABS 2 U S Army Engineer Waterways Experiment Station Vicksburg MS Wright S J 1984 Buoyant jets in density stratified crossflow J Hydraul Engineer Am Soc Civil Engineers 110 643 656 Zeller R W et al 1971 Heated surface jets in steady crosscurrent J Hydraul Engineer Am Soc Civil Engineers 97 1403 1426
13. Grid points depths Velocity Data Type of velocity profile Water Depth for Averaged Velocity Vertically averaged x direction velocity Vertically averaged z direction velocity Water depths for 2 point profile Velocities for 2 point profile in X direction Velocities for 2 point profile in z direction Velocities for entire grid in x direction Velocities for entire grid in z direction Input Execution and Output Keys Processes to simulate Duration of simulation Long term time step for diffusion Convective descent output option Disposal Operation Types OTe mu m mm Units Options g L ug Kg ug L ug L ug L ft ft ft C ft degrees degrees ft g cc ppt Optional Celsius Optional ft V ft ft sec ft sec ft ft sec ft sec ft sec ft sec Table C 2 STFATE Model Input Parameters continued Parameter Input Execution and Output Keys continued Collapse phase output option Number of print times for long term diffusions Location of upper left corner of mixing zone on grid Location of lower right corner of mixing zone on grid Water quality standards at border of mixing zone for contaminant of concern Contaminant of concern Contaminant concentration in sediment Background concentration at disposal Site Location of upper left corner of zone of initial dilution ZID on grid
14. There are four options available The two options of interest here are F3 Section 404 b 1 Reg Analysis for Navigable Waters see step g and F4 Determine Contaminant of Concern Based on Dilution Needs see step d This option is used only for Tier II evaluations Contaminant Data File Selection Menu Selecting F4 from the Evaluation Selection Menu brings up this menu which has the same structure as the Input Data File Selection Menu see step g Use one of the options to select an active file C 26 Menu for Selection of a Contaminant for Modeling Selecting F4 from the Contaminant Data File Selection Menu brings up this menu data analysis routine controlled by this menu is used to select a specific contaminant for modeling Such a selection is necessary under the Tier II analysis both for evaluation of the need for additional testing and for water quality comparisons with standards Execution of the open water disposal model for these Tier II analyses allows use of only one contaminant this option 15 used to select that contaminant Bulk sediment and background contaminant concentrations and water quality standards are required to compute the required dilutions for the evaluation of the need for additional testing The contaminant requiring the largest dilution should be subsequently modeled Elutriate and background concentrations and water quality standards are required to compute the required dilutions for the dissolve
15. When calculation of the mixing zone is desired zeros are entered in the boxes for the upper and lower mixing zone corners In this example the contaminant of concern is lead which has a background concentration of 0 0002 mg L The predicted initial concentration in the fluid fraction is 0 174 mg L and the water quality standard at border or mixing zone is 0 0032 mg L After data are entered press PAGE DOWN to receive a screen which asks if a zone of initial dilution is desired For this example the answer NO is selected using arrow keys Press PAGE DOWN to specify the depths at which water quality results are desired The number of depths between 2 and 5 and the corresponding depth value are entered In this example two depths of 15 and 39 ft are entered Using PAGE DOWN a data entry screen for the duration of simulation long term time step and specifications for printed output are displayed Since the example is for water column evaluation a one hour 3600 s duration and a time step of 300 s is input Output concerning convective descent and collapse phase are requested to permit review of the simulation Particular times are not of importance for an example so NO is chosen and the output is produced quarterly 900 1800 2700 and 3600 s Specific times can be requested by choosing YES and another screen will appear for entering these times but the times must be increments of the selected time step Again PAGE DOWN is pressed returning to the
16. approximated C6 2 Sample Computations The following computations are presented to illustrate the dilution volume method for a continuous effluent discharge The following input values are used in the sample computations Volume of effluent discharge per unit time V 44 cu ft sec Turbulent dissipation parameter 0 005 Water column depth d 10 ft Water velocity V 0 5 ft sec Initial width of plume 2r 30 ft Background concentration Cgo 0 1 mg L Effluent discharge concentration C 30 mg L Applicable water quality standard C 0 5 mg L The required volume per unit time will be V V D 44 30 0 5 0 5 0 1 3245 cu ft sec The required width of the mixing zone will be ae Va 3245 dV 10 0 5 49 ft The time required to achieve the lateral spread L will be 77 E 1 2 3 2 3 m mt 094 64 149 15 PEE 0 094 649 0 149 15 1228 sec The length of the mixing zone will be X 0 5 ft sec 1228 sec 614 ft Thus the proposed mixing zone would have dimensions of Surface area 58 614 208 453 sq fi Maximum dimensions 614 ft by 649 ft This information would be used in considering the compatibility of the size of the mixing zone required to dilute the discharge with the available mixing zone 78 C7 0 REFERENCES Ariathurai R MacArthur and Krone 1977 Mathematical model of estuarial sediment transport Technical Report
17. 0 0 0 0 0 0 0 0 0 0 O O 160000 0 0 0 0 0 i 0 0 0 0 0 0 0 0 00 OOOO 1700000 0 0 0 00000000 180000 0 0 0 0 010101 01 01 0 0 0000 0 0 190000 0 0 0 01 03 246 09 13 16 17 16 13 09 06 03 10 0 2000000 0 0 01 03 08 16 29 46 63 76 81 76 63 46 29 16 080 0 210000 0 0 0 0 02 07 16 33 58 90 1 2 1 5 1 6 1 5 1 2 90 58 33 160 0 0 0 0 0 220000 0 0 0 0 02 06 15 30 53 83 1 1 1 3 1 4 1 3 1 1 83 53 30 150 0 0000 2300000 0 0 0 01 02 06 13 23 35 48 59 62 59 48 35 23 13 060 0 0000 2400000 0 0 0 01 02 04 06 08 10 10 10 08 06 04 02 010 000000 2500000 0 0 0 00000000 260000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 270000 0 0 0 0 0 0 0 0 0 0 00 280000 0 0 0 0 0 0 0 0 0 O 290000 0 0 0 0 0 0 0 0 0 0 0 0 00 300000 0 0 0 0 0 0 0 0 0 0 31
18. 0 531E 02 1650 750 0 42 15 0 0 435E 02 0 455E 02 1800 750 0 50 15 0 0 374E 02 0 394E 02 1950 750 0 58 15 0 0 323E 02 0 343E 02 2100 750 0 67 15 0 0 281E 02 0 301E 02 2250 750 Figure C 7 Selected Output for Barge Disposal 0 75 0 83 1 00 0 08 0 17 0 25 0 33 0 50 0 58 0 67 0 75 0 83 0 92 1 00 0 08 0 17 0 25 0 33 0 42 0 50 0 58 0 75 0 83 0 92 1 00 0 08 0 17 0 25 0 33 0 42 0 50 0 58 0 67 0 75 0 83 0 92 1 00 0 08 0 17 0 25 0 33 0 42 0 50 0 58 0 67 0 75 0 83 0 92 1 00 Figure 7 15 0 15 0 15 0 39 0 10 0 10 0 10 0 10 0 10 0 10 0 10 0 10 0 10 0 10 0 10 0 10 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 20 0 0 246 02 0 216 02 0 191 02 0 169 02 0 103E 01 0 231E 02 0 112 02 0 950 03 0 810 03 0 695 03 0 601 03 0 522 03 0 457E 03 0 401E 03 0 355E 03 0 315E 03 0 524E 02 0 135E 02 0 185E 02 0 156E 02 0 133E 02 0 114E 02 0 988E 03 0 859E 03 0 752bE 03 0 661E 03 0 584E 03 0 518E 03 0 237E 01 0 695E 02 0 421E 02 0 357E 02 0 304E 02 0 261E 02 0 226E 02 0 196E 02 0 171E 02 0 151E 02 0 133E 02 0 118E 02 0 393E 01 0 126E 01 0 683E 02 0 578E 02 0 492 02 0 423E 02 0 365E 02 0 318E 02 0 278E 02 0 244E 02 0 216E 02 0 191E 02 C 40 0 266E 02 0 236E 02 0 211E 02 0 189E 02 0 105E 01 0 251E 02 0 132 02 0 115E 02 0 101E 02 0 895E 03 0 801E 03 0 722 03 0 657 03 0
19. 00 2700 750 0 170E 00 0 92 0 0 0 486E 00 2850 750 0 439E 00 THE TOXICITY STANDARD IS VIOLATED OUTSIDE THE MIXING ZONE AT 0 92 HOURS 1 00 0 0 0 433E 00 3000 750 0 433E 00 THE TOXICITY STANDARD IS VIOLATED OUTSIDE THE MIXING ZONE AT 1 00 HOURS 0 08 0 0 0 672E 0 1350 750 0 251 25 0 17 0 0 0 338 0 1500 750 0 180 05 0 25 0 0 0 299E 0 1650 750 0 345E 04 0 33 0 0 0 264E 0 1800 750 0 296 03 0 42 0 0 0 232 0 1950 750 0 148 02 0 50 0 0 0 204 0 2100 750 0 490 02 0 58 0 0 0 180 0 2250 750 0 120 01 0 67 0 0 0 159 0 2400 750 0 238 01 0 75 0 0 0 141 0 2550 750 0 401 01 0 83 0 0 0 125 0 2700 750 0 387E 00 0 92 0 0 0 111E 0 2850 750 0 100E 01 THE TOXICITY STANDARD IS VIOLATED OUTSIDE THE MIXING ZONE AT 0 92 HOURS 1 00 0 0 0 989E 00 3000 750 0 989E 00 THE TOXICITY STANDARD IS VIOLATED OUTSIDE THE MIXING ZONE AT 1 00 HOURS Figure C 14 Selected Output for Hopper Dredge Disposal continued RESULT 0 08 20 0 17 20 0 25 20 0 33 20 0 42 20 0 50 20 0 58 20 0 67 20 0 75 20 0 83 20 0 92 20 1 00 20 0 08 30 OLET 30 0 25 30 0 33 30 0 42 30 0 50 30 0 58 30 0 67 30 0 75 30s 0 83 30 0 92 30 THE TOXICITY 1 00 30 THE TOXICITY THE TOXICITY 0 08 40 0 07 40 0 25 40 0 33 40 0 42 40 0 50 40 0 58 40 0 67 40 0 75 40 0 83 40 0 92 40 1 00 40
20. 1800 750 0 480 03 0 42 20 0 0 376 0 1950 750 0 240 02 0 50 20 0 0 331 0 2100 750 0 794 02 0 58 20 0 0 292 0 2250 750 0 195 01 0 67 20 0 0 258 0 2400 750 0 386 01 0 75 20 0 0 228 0 2550 750 0 649 01 0 83 20 0 0 202E 0 2700 750 0 627E 00 THE TOXICITY STANDARD IS VIOLATED OUTSIDE THE MIXING ZONE AT 0 83 HOURS 0 92 20 0 0 180E 0 2850 750 0 162E 01 THE TOXICITY STANDARD IS VIOLATED OUTSIDE THE MIXING ZONE AT 0 92 HOURS 1 00 20 0 0 160E 0 3000 750 0 160E 01 THE TOXICITY STANDARD IS VIOLATED OUTSIDE THE MIXING ZONE AT 1 00 HOURS 0 08 39 0 0 245E 0 500 750 0 805 26 0 17 39 0 0 902 00 500 750 0 503E 06 0 25 39 0 0 797 00 650 750 0 920 05 0 33 39 0 0 702 00 800 750 0 789 04 0 42 39 0 0 618 00 950 750 0 395 03 0 50 39 0 0 544 00 2100 750 0 131 02 0 58 39 0 0 480 00 2250 750 0 321 02 0 67 39 0 0 424 00 2400 750 0 634 02 0 75 39 0 0 375E 00 2550 750 0 107 01 0 83 3920 0 332 00 2700 750 0 103E 00 0 92 39 0 0 295E 00 2850 750 0 267E 00 1 00 39 0 0 263E 00 3000 750 0 263E 00 0 08 0 0 0 135E 01 1350 750 0 560 26 0 17 0 0 0 148 01 1500 750 0 735 06 0 25 0 0 0 131 01 1650 750 0 151 04 0 33 0 0 0 116 01 1800 750 0 130 03 0 42 0 0 0 102 01 1950 750 0 649 03 0 50 0 0 0 896 00 2100 750 0 215 02 0 58 0 0 0 789 00 2250 750 0 528 02 0 67 0 0 0 697 00 2400 750 0 104 01 0 75 0 0 0 617 00 2550 750 0 176 01 0 83 0 0 0 547
21. 3 Estimate the lateral mixing coefficient by using one of the following equations In rivers 65 E 0 3 du In estuaries dux where E lateral mixing coefficient m sec d average channel depth m u shear velocity m sec The values of lateral mixing coefficient are derived from Fischer et al 1979 and are based on experimental studies of dispersion in various rivers Lateral mixing coefficients have been shown to vary widely from one location to another and the above equations give the lowest reasonable values so that estimates of mixing zone size will be conservative Step 4 Estimate mixing zone length If the assumptions presented earlier are valid the mixing zone will have a shape similar to the one shown in Figure C 18 The length of the mixing zone measured parallel to the bank can be estimated as 1 I C Si where L mixing zone length m Q effluent volumetric discharge rate m sec Step 5 Check length dependent assumptions Step 5 1 The flow in the water body near the mixing zone can be treated as a steady state flow as long as 66 where L predicted mixing zone length m u cross sectional average velocity instantaneous or averaged over a few minutes m sec T time taken for the observed value of to change by 10 percent in seconds Step 5 2 The lateral dispersion of the effluent plume will not be restri
22. 750 0 75 30 0 0 168E 02 0 188E 02 2400 750 0 83 30 0 0 148E 02 0 168E 02 2550 750 0 92 30 0 0 131E 02 0 151E 02 2700 750 1 00 30 0 0 116E 02 0 136E 02 2850 750 0 08 40 0 0 531E 02 0 551E 02 1200 750 0 17 40 0 0 172bE 02 0 192 02 1350 750 0 25 40 0 0 924 03 0 112 02 1500 750 0 33 40 0 0 781 03 0 981 03 1650 750 0 42 40 0 0 666 03 0 866 03 1800 750 0 50 40 0 0 572 03 0 772 03 1950 750 0 58 40 0 0 494 03 0 694 03 2100 750 0 67 40 0 0 430 03 0 630E 03 2250 750 0 75 40 0 0 376E 03 0 576E 03 2400 750 0 83 40 0 0 330E 03 0 530E 03 2550 750 0 92 40 0 0 292 03 0 492 03 2700 750 1 00 40 0 0 259 03 0 459 03 2850 750 ESTIMATES AREAS CURRENTLY VIOLATION SNAPSHOT AND MIXING ZONES ACCUMULATED AREA OF VIOLATION SNAPSHOT ACCUMULATED AREA SQ FT L FT AREA SQ FT L FT W FT 0 975000 05 570 0 975000 05 570 171 0 600000 05 391 0 112500 06 570 197 0 450000 05 391 0 150000 06 695 216 0 450000 05 391 0 187500 06 828 227 0 375000 05 292 0 225000 06 966 233 0 225000 05 212 0 247500E 406 1107 224 0 225000 05 212 0 270000 06 1250 216 0 750000 04 158 0 277500 06 1395 199 0 000000 00 0 0 277500 06 1395 199 0 000000 00 0 0 277500 06 1395 199 0 000000 00 0 0 277500 06 1395 199 0 000000 00 0 0 277500 06 1395 199 Figure 7 Selected Output for Barge Disposal c
23. B Cloud ambient density gradient ratio H B Turbulent thermal entrainment H B Entrainment in collapse H B Stripping factor H B The use of a parameter for disposal operations by a multiple bin hopper dredge is indicated in the table by an H while a parameter used for disposal from a split hull barge or scow is indicated by a B The use of parameter for the constant depth option or variable depth option is indicated in the table by a C or V respectively Other optional uses for parameters are so indicated 21 At the conclusion of the collapse phase time dependent information concerning the size of the collapsing cloud its density and its centroid location and velocity as well as contaminant and solids concentrations be requested model performs the numerical integrations of the governing conservation equations in the descent and collapse phases with a minimum of user input Various control parameters that give the user insight into the behavior of these computations are printed before the output discussed above 15 provided At various times as requested through input data output concerning suspended sediment concentrations can be obtained from the transport diffusion computations With Gaussian cloud transport and diffusion only concentrations at the water depths requested are provided at each grid point For evaluations of initial mixing results for water column concentrations can be computed in terms
24. Example C 34 Selected Output for Barge Disposal C 39 Peak Lead Concentration in Water Column as a F Time for the Barge Disposal Example C 43 Lead Concentration Contours for 15 ft Depth at 3600 sec for the Barge Disposal Example C 44 Plot of Required Mixing Zone for the Barge Disposal Example C 44 Schematic of Example Disposal Site for Multiple bin Hopper Dredge Disposal 48 X direction Velocity Profile for Hopper Dredge Example C 49 Schematic of Hopper Dredge with 6 Bins C 51 Selected Output for Hopper Dredge Disposal C 54 Peak Fluid Ratio as a F Time for the Hopper Dredge Disposal Example C 57 Fluid Ratio Contours for 20 ft Depth at 3600 sec for the Hopper Dredge Disposal Example C 58 Plot of Required Mixing Zone for the Hopper Disposal Example C 59 Schematic of a Mixing Zone for a Single Effluent Source C 61 Projected Surface Area and Volume Equations for CDF Effluent Discharge with Prevailing Current C 74 C 1 C1 0 INTRODUCTION This appendix presents a variety of techniques for evaluating the size of mixing zones for dredged material discharges These techniques include analytical approaches and computer models for evalu ation of discrete discharges from barges or hoppers for continuous discharges from pipelines and for effluent discharges from confined disposal facilities CDFs Discussions of the applicability and limitations of the techniques and stepwise procedures for performing the required calculations or applyi
25. Location of lower right corner of zone of initial dilution ZID on grid Water quality standards at border of ZID for contaminant of concern Number of depths in water column for which output is desired Depths for transport diffusion output Predicted initial concentration in fluid fraction Dilution required to meet toxicity standards Dilution required to meet toxicity standards at border of ZID Material Description Data Total volume of dredged material in the Hopper dredge Number of distinct solid fractions Solid fraction descriptions Solid fraction specific gravity Solid fraction volumetric concentration Solid fraction fall velocity Solid fraction deposited void ratio Solid fraction critical shear stress Cohesive yes or no Stripped during descent yes or no Moisture content of dredged material as multiple of liquid limit Water density at dredging site Salinity of water at dredging site Temperature of water at dredging site Desired number of layers Volume of each layer Velocity of vessel in x direction during dumping of each layer Velocity of vessel in z direction during dumping of each layer Disposal Operation Types H B H B H B gt ino U Pye TETT mummmHm Units Option ft ft mg L mg Kg mg L ft ft mg L ft mg L percent percent yd ft sec Ibs sq ft Cohesive g cc ppt Opti
26. directory Start the program by entering ADDAMS STFATE at the DOS prompt If started by entering ADDAMS the program will display first the ADDAMS logo and then an Application Selection Menu An application in the ADDAMS software consists of one or more standalone computer programs or numerical models for performing a specific analysis only ADDAMS application module provided on diskette with this manual is named STFATE STFATE consists of programs for evaluating open water disposal of dredged material Select the STFATE application module from the Application Selection Menu module will display some logos and then a reference screen with points of contact After the user strikes any key the module displays the STFATE Activity Selection Menu If started by entering STFATE the module starts with STFATE logos and the reference screen and proceeds in the same manner as if the module was started by entering ADDAMS Activity Selection Menu The activity selection menu may be considered the main menu for the STFATE application The first option is used to build or edit an input data file The second option executes the simulation third option is used to print or view output fourth option generates graphics The fifth option is used to configure the graphics software for the hardware present Evaluation Selection Menu Selecting F1 from the STFATE Activity Selection Menu brings up the STFATE Evaluation Selection Menu
27. of the STFATE model can be downloaded from the Internet web site http www epa gov OST pubs ITM html Go to Short Term Fate Model for Open Water Barge Hopper Discharges STFATE and download the two zipped files STFATEI zip and STFATE2 zip to a directory on the hard disk dedicated for the STFATE model e g CASTFATE Unzip each file using pkunzip type loadfate to dearchive the files then type STFATE to start the model When unzipping the user should type y when queried as to overwriting a particular file A demonstration model DEMO can also be downloaded to another directory on the hard disk Type startdem to unzip and run the demonstration model C2 6 3 User Interface The STFATE module of ADDAMS employs a menu driven environment with a full screen data entry method In general single keystrokes usually the F1 through F10 function keys the number keys Esc key or the arrow keys and the Enter key are required to select menu options in the system Menus are displayed on the screen Cursor keys are used to select from among highlighted input fields displayed in reverse video much like a spreadsheet program To enter alphanumeric data the user moves the cursor to the cell of interest using the up and down arrows to move respectively up and down the Tab and Shift Tab keys to move respectively right and left The Enter key is also used to move forward through the cells The left and right arrow keys are used to move
28. the directory specified in the path An existing data file name may be selected from the list to use as the active data file name for reading existing data After the 27 input file has been selected press F4 to build or edit the input data file The input data that are stored in the selected file are then read and will later be displayed on the input data screens to be reviewed and edited If the specified file could not be found did not exist the program will provide the user the opportunity to initialize the file and start creating a new data set Disposal Operation Selection Menu Selecting F4 from the Input Data File Selection Menu brings up this menu The selection of a disposal type under this menu controls the input data requests the type of execution data file that will be built and the open water disposal model that will be executed Select the appropriate type of disposal F1 Disposal from a Multiple Bin Hopper Dredge or F2 Disposal from a Split Hull Barge or Scow The STFATE Input Selection Menu will then be displayed Input Selection Menu Five types of input data have to be entered as shown in Table C 2 and Figure C 4 plus any desired changes in the default set of model coefficients before an execution data file can be written Default values are included for all of the model coefficients requested Enter data by paging down through the data entry screens making selections and filling in the cells for each optio
29. using direct pipeline discharge direct mechanical placement or release from hopper dredges or scows Discharges of effluent from CDFs can be introduced to the receiving waters in a variety of ways including direct pipeline outfalls or open channels For purposes of evaluation of initial mixing barges or hopper dredge discharges are discrete discharges while direct discharge from a pipeline dredge or CDF effluent should be considered continuous discharges C1 4 1 Barge Discharge Bucket or clamshell dredges remove the sediment being dredged at nearly its in situ density and place it on a barge or scow for transportation to the disposal area Although several barges may be used so that the dredging is essentially continuous disposal occurs as a series of discrete discharges Barges are designed with bottom doors or with a split hull and the contents may be emptied within seconds essentially as an instantaneous discharge Often sediments dredged by clamshell remain in fairly large consolidated clumps and reach the bottom in this form Whatever its form the dredged material descends rapidly through the water column to the bottom and only a small amount of the material remains suspended Clamshell dredge operations may also be used for direct material placement adjacent to the area being dredged In these instances the material also falls directly to the bottom as consolidated clumps C1 4 2 Hopper Dredge Discharge The characteristics and ope
30. velocity of 0 5 ft s at a depth of 30 ft and 0 3 ft s at 38 ft are entered The z direction velocity is 0 ft s Although zero velocity can be input it is recommended that the speed of the resultant velocity vector be set at least 0 1 ft s because most open bodies of water have some motion occurring at all times When the input of velocity data is complete press PAGE DOWN to return to the STFATE Input Selection Menu Figure 5 Figure C 6 C 34 0 ft 1550 ft Grid Pt 1 Grid Pt 32 0 ft Grid Pt 1 1000 ft Grid Boundary Water Current 0 to 0 5 ft s Water Depth 40 ft 4650 ft Grid Pt 32 Schematic of Example Disposal Site for Barge Disposal Velocity ft s 0 0 0 3 0 5 Depth ft X direction Velocity Profile for Barge Example 35 C2 8 1 1 3 Input Execution and Output Keys At this point F3 Input Execution and Output Keys is selected in the same method as previously described which brings the Simulation Selection Menu to the monitor Since initial mixing calculations are desired F3 DESCENT COLLAPSE AND LONG TERM DIFFUSION is selected Next the Evaluation Selection Menu appears on the monitor and since this example requires comparison to water quality concentrations for lead the F2 TIER COMPARE WATER QUALITY is chosen This selection also provides for calculation of the size length and width of the mixing zone required to prevent violation of a specified water quality standard
31. 0 5 ft s Water Depth 40 ft 4650 ft Grid Pt 32 Figure C 11 Schematic of Example Disposal Site for Multiple bin Hopper Dredge Disposal C2 8 2 1 2 Velocity Data for Hopper Disposal Example The selection of F2 Velocity Data from the STFATE Input Selection Menu brings up the Velocity Profile Selection Menu In this example a depth averaged water velocity profile Fig C 12 for a constant depth is selected by pressing the F2 key or highlighting the selection using arrow keys and then pressing PAGE DOWN The next data entry screen appears on the monitor and the velocity and constant water depth data are entered in the highlighted boxes In this case x direction velocity of 0 5 ft s at a depth of 40 ft and z direction velocity of 0 ft s are entered Although zero velocity can be input it is recommended that the speed of the resultant velocity vector be at least 0 1 ft s because most open bodies of water have some motion occurring at all times When the input of velocity data is complete press PAGE DOWN to return to the STFATE Input Selection Menu 49 Velocity ft s 0 0 0 5 Depth ft Logarithmic Profile Figure C 12 X direction Velocity Profile for Hopper Dredge Example C2 8 2 1 3 Input Execution and Output Keys F3 Input Execution and Output Keys is selected as previously described and the Simulation Selection Menu appears Initial mixing calculations are desired for the hopper disposal so F3 DESCENT COLLA
32. 00 0 0 0 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 50000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 6 0000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 7 0000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 8 0000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Orr G 0 70 9 0000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 100000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 110000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 120000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 130000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 140000 0 0 0 0 x x gt x s gt Y x gt w x gt gt 0 0 0 0 0 0 OOOO 15 OOOO 0 0 0 00 0 0 0 16 OOOO 0 0 if if if 01 01 01 01 01 if 0 0 0 0 0 0 170000 0 0 01 01 02 04 06 08 10 11 12 11 10 08 06 04 02 01 01 0 0 0 0 180000 0 0 01 02 04 08 13 21 30 40 49 55 57 55 49 40 30 21 13 08 04 0 0 0 0 0 0 190000 0 0 01 02 05 10 19 33 51 73 97 11 13 14 13 11 7 73 51 19 10 0 0 0 0 200000 0 0 01 03 06 12 23 39 61 88 11 14 16 16 16 14 11 88 61 39 23 12 0 0 0 0 210000 0 0 01 07 13 23 36 51 68 84 95 99 95 84 68 51 36 23 13 07 0 0 0 0 0 0 220000 0 0
33. 149 1 P where t required time for lateral spreading sec L necessary width of the front edge of mixing zone ft r one half initial width of the plume at point of discharge radius of initial surface mixing ft turbulent dissipation parameter Values for range from 0 00015 to 0 005 with a value of 0 005 being appropriate in a dynamic environment such as an estuary Brandsma and Divoky 1976 discussed earlier values for will be influenced by the method of disposal and will be site specific The calculated time can then be used to determine the longitudinal distance the discharge will travel as it is spreading to the required width This distance can be computed from where X longitudinal movement of discharge ft V velocity of water at disposal site ft sec t necessary time of travel sec The results of the previous equations can then be combined to estimate the projected surface area of the proposed discharge This area can be computed as where A surface area ft L width of front edge of mixing zone ft r radius of initial surface mixing ft X length of the mixing zone ft 76 This approach will characterize a proposed discharge by defining the volume of dilution water per unit time that will be required to achieve some acceptable concentration at the edge of the mixing zone Also the length and width and hence the surface area of the necessary mixing zone will be
34. 601 03 0 555E 03 0 515E 03 0 544E 02 0 155E 02 0 205E 02 0 176E 02 0 153E 02 0 134E 02 0 119E 02 0 106E 02 0 952 03 0 861E 03 0 784E 03 0 718E 03 0 239E 01 0 715E 02 0 441E 02 0 377E 02 0 324E 02 0 281E 02 0 246E 02 0 216E 02 0 191E 02 0 171E 02 0 153E 02 0 138E 02 0 395E 01 0 128E 01 0 703E 02 0 598E 02 0 512 02 0 443E 02 0 385E 02 0 338E 02 0 298E 02 0 264E 02 0 236E 02 0 211E 02 2400 2550 2700 2850 1200 1350 1500 1650 1800 1950 2100 2250 2400 2550 2700 2850 1200 1350 1500 1650 1800 1950 2100 2250 2400 2550 2700 2850 1200 1350 1500 1650 1800 1950 2100 2250 2400 2550 2700 2850 1200 1350 1500 1650 1800 1950 2100 2250 2400 2550 2700 2850 Selected Output for Barge Disposal continued 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 750 41 0 08 30 0 0 239 01 0 241E 01 1200 750 0 17 30 0 0 794E 02 0 814E 02 1350 750 0 25 30 0 0 414E 02 0 434E 02 1500 750 0 33 30 0 0 350E 02 0 370E 02 1650 750 0 42 30 0 0 299E 02 0 319E 02 1800 750 0 50 30 0 0 256E 02 0 276E 02 1950 750 0 58 30 0 0 221E 02 0 241E 02 2100 750 0 67 30 0 0 193E 02 0 213E 02 2250
35. D 77 12 U S Army Engineer Waterways Experiment Station Vicksburg MS Bokuniewicz H J et al 1978 Field study of the mechanics of the placement of dredged material at open water disposal sites Technical Report D 78 7 U S Army Engineer Waterways Experiment Station Vicksburg MS Bowers G W and M K Goldenblatt 1978 Calibration of a predictive model for instantaneously discharged dredged material U S Environmental Protection Agency Corvallis OR EPA 699 3 78 089 Brandsma M G and D J Divoky 1976 Development of models for prediction of short term fate of dredged material discharged in the estuarine environment Contract Report D 76 5 DACW39 74 C 0075 prepared by Tetra Tech Inc under contract to U S Army Engineer Waterways Experiment Station Vicksburg MS Brandsma M G and T C Sauer Jr 1983 Mud discharge model report and user s guide Exxon Production Research Co Houston TX Brooks N H 1960 Diffusion of sewage effluent in an ocean current Proceedings of First International Conference on Waste Disposal in the Marine Environment Pergamon Press NY NY Buhler J and W Hauenstein 1981 Axismetric jets in a crossflow 19th Congress of the International Association of Hydraulic Research New Delhi India February 1 8 1981 Donekar R L and Jirka G H 1990 Expert System for Hydrodynamic Mixing Zone Analysis of Conventional and Toxic Submerged Singe Port Discharges CORMIX1 US Environme
36. Dredge Discharge C 5 C1 4 4 Confined Disposal Facility CDF Effluent Discharge C 5 1 5 Applicability of Models and Techniques C 6 1 5 1 General Considerations C 6 C1 5 2 Considerations for Tidally Influenced Rivers and Estuaries C 7 C1 5 3 Recommended Models and Techniques C 8 C2 0 SHORT TERM FATE MODEL FOR OPEN WATER BARGE AND HOPPER DISCHARGES STFATE C 10 C2 1 Introduction ou ua l Q l y ESTE 10 2 2 Theoretical Basis irora taa Oe wx WU gu 10 C2 2 1 5 h MON DOE a C 11 2 2 2 Dynamic Collapse C 12 2 2 3 Transport diffusion 12 2 3 Model Capabilities use RR AR sub ua C 15 2 3 1 Disposal Methods pp Ee REESE d C 15 2 3 2 Ambient Environment C 16 2 3 3 Time varying Fall C 16 2 3 4 Conservative Constituent Computations C 17 C2 4 Model Inp t v ud bees SER RUE SOR EU C 17 C2 5 Model Output 7 p
37. EVALUATION OF DREDGED MATERIAL PROPOSED FOR DISCHARGE IN WATERS OF THE U S TESTING MANUAL FINAL WORKGROUP DRAFT INLAND TESTING MANUAL Prepared by ENVIRONMENTAL PROTECTION AGENCY Office of Water Office of Science and Technology Washington D C and DEPARTMENT OF THE ARMY United States Army Corps of Engineers Washington D C March 1995 APPENDIX EVALUATION OF MIXING TABLE OF CONTENTS Page No Table of Contents 1 List of Tables iii List of Figures iv APPENDIX C EVALUATION OF INITIAL MIXING C1 0 INTRODUCTION Su oc ee ck Sed Se aaa Ie Be C 1 Background 5522225555 2 2 C 1 1 2 Regulatory Considerations C 2 C1 3 Potential Applications of Initial Mixing C 2 C1 3 1 Screen to Determine Need for Additional Water Column Testing C 3 C1 3 2 Evaluation of Dissolved Contaminant Concentrations by Comparison with Water Quality Standards C 3 C1 3 3 Evaluation of Concentrations of Suspended Plus Dissolved Constituents by Comparison with Toxicity Test Results C 3 1 4 Physical Characteristics of Dredged Material Discharges C 4 1 4 1 Barge Discharge eve ur po RE 4 1 42 Hopper Dredge Discharge C 4 C1 4 3 Pipeline
38. FastTABS was designed to allow easy application of each of the models in the TABS system which include hydrodynamics constituent and sediment transport The FastTABS software runs on Macintosh and DOS based personal computers as well as most UNIX workstations primer user s manual and tutorial are available A limited government license allows USACE office use of the FastTABS software supplied through the USACE Waterways Experiment Station WES Other users may obtain the software from Brigham Young University 801 378 5713 The point of contact for additional information is Mr David R Richards USACE Waterways Experiment Station ATTN CEWES HE S 3909 Halls Ferry Road Vicksburg MS 39180 6199 601 634 2126 C 73 C6 0 DILUTION VOLUME METHOD FOR CDF EFFLUENT DISCHARGES C6 1 Approach A simplified approach to evaluation of mixing zones for CDF effluent discharges is presented in this section in which the volume of water required for dilution is expressed as a rate of flow Environmental Effects Laboratory 1976 This approach is generally applicable in both riverine and estuarine conditions However the approach should only be applied where there is a discrete discharge source such as a conduit or a weir Since the effluent discharge will occur at a specified rate V the volume of ambient site water per unit time that would be required to dilute the discharge to acceptable levels can be defined as V V D V
39. For example a moving hopper dredge disposal can be modeled by assuming that the material in each bin convects downward as one cloud In addition through the use of multiple convecting clouds with varying characteristics the consolida tion that often occurs in scows or barges can be accounted for more accurately Since the solids con centration in discharged dredged material is usually low each cloud is expected to behave as a dense liquid thus a basic assumption is that a buoyant thermal analysis is appropriate The equations governing the motion are those for conservation of mass momentum buoyancy solid particles and vorticity These equations are straightforward statements of conservation principles details are presented in Koh and Chang 1973 and Brandsma and Divoky 1976 It should be noted that the entrainment coefficient associated with the entrainment of ambient fluid into a descending hemispherical cloud is assumed to vary smoothly between its value for a vortex ring and the value for C 12 turbulent thermals Model results are relatively sensitive to the entrainment coefficient which in turn is dependent upon the material being disposed the higher the moisture content the larger the value of the entrainment coefficient Laboratory studies by Bowers and Goldenblatt 1978 resulted analytical expressions for the entrainment drag and added mass coefficients as functions of the moisture content These have been incorporated i
40. Internet web site http www epa gov OST pubs ITM html see Section C2 6 2 The model is appropriate for instantaneous discharges from barges or scows and sequential discharges from hopper dredges C2 2 Theoretical Basis The behavior of the material during disposal is assumed to be separated into three phases convective descent during which the disposal cloud falls under the influence of gravity and its initial momentum is imparted by gravity dynamic collapse occurring when the descending cloud either impacts the bottom or arrives at a level of neutral buoyancy where descent is retarded and horizontal spreading dominates and passive transport dispersion commencing when the material transport and spreading are determined more by ambient currents and turbulence than by the dynamics of the disposal operation Figure C 1 illustrates these phases C 11 CONVECTIVE DYNAMIC COLLAPSE LONG TERM DESCENT ON BOTTOM PASSIVE BOTTOM DIFFUSIVE SPREADING DIFFUSION ENCOUNTER GREATER THAN DYNAMIC SPREADING Figure C 1 Illustration of Placement Processes C2 2 1 Convective Descent In STFATE multiple convecting clouds that maintain a hemispherical shape during convective descent are assumed to be released By representing the disposal as a sequence of convecting clouds released at a constant time interval during the total time required for the material to leave the disposal vessel real disposal operations be more accurately simulated
41. PSE AND LONG TERM DIFFUSION is selected Next the Evaluation Selection Menu appears on the monitor and since this example requires comparison to toxicity results the F3 TIER COMPARE TOXICITY RESULTS is chosen The first input execution and output keys data entry screen appears and provides for the input of the mixing zone characteristics and the toxicity standard for dilution as a percentage of the initial water column concentration prior to disposal For this example the mixing zone upper left corner x 750 ft z 450 ft and lower right corner x 3000 ft z 2 1050 ft are entered and the dilution requirement to meet the toxicity standard is appropriately entered percent of initial concentration is 0 4 After entering the data press PAGE DOWN to receive the next screen It asks if a zone of initial dilution is desired and the answer is NO for this example Press PAGE DOWN to receive the next screen which requests the number of depths 2 to 5 and depths where output on concentrations are desired In this example 2 depths 20 and 39 ft are entered Using PAGE DOWN the next data entry screen requests further input concerning the duration of simulation long term time step and specifications for printed output Since the example is for water column evaluation the one hour 3600 s duration and a time step of 300 s are input Output concerning convective descent and collapse phase are not of particular interest for this example
42. Step 4 Estimate mixing zone length Estimate using the problem statements Q 15 cfs 0 425 m sec 3 5 ug L 3 5 x 10 C 025 pg L 2 5 10 mg L C lt 01 pg L 1 0 x 10 mg L In order to be conservative it would be wise to assume that the background concentration is only just under the detection limit rather than zero Therefore use 69 C 10 x 104 mg L Calculate mixing zone length 1 TEU C i 1 1 0 0441 1 0 579 m sec 0 425 2 3 5 x 10 mg L 2 5 1 0 x 10 mg L 1 2 54 L 190 m 623 f Step 5 Check length dependent assumptions Step 5 1 Verify that the flow of the water body near the mixing zone can be treated as a steady state flow uT lt 10 therefore T gt 101 C 70 gt 10 190 m 0 579 m sec gt 3 280 sec 55 min This is acceptable since the river flow will certainly not change by 10 percent in less than 1 hour Step 5 2 w gt 80 0441 m sec 190 m i 0 579 mlsec W gt 10 8 m This condition is amply satisfied since W equals 146 m Step 6 Estimate maximum width of mixing zone Estimate the maximum mixing zone width as 0 484 Q C u C C d 0 484 0 425 m sec 1 3 5 x 10 mg L 0 579 m sec 5 1 0 x 10 mg L 10 54 m Y Y 33 m 10 7 fi 71 Since the mixing zone is predicted to h
43. a corresponding thickness are also determined Since a normal distribution is assumed for material in the small clouds deposited material is also assumed to take a normal distribution horizontally on the bottom basic assumption in the model is that once material is deposited on the bottom it remains there i e no allowance is made for either erosion or bed load movement of material However deposition is prohibited if the computed bottom shear stress exceeds a specified critical shear stress for deposition for each solid fraction This allows for application at dispersive sites The discussion presented above for transport diffusion of solids also applies to the disposed fluid with its dissolved constituents It is conservatively assumed that all of the fluid remaining in the collapsing cloud and its dissolved contaminants are released to the water column in Gaussian clouds during collapse The contaminants are assumed to be conservative with no further adsorption on or desorption from the solids in the water column or deposited on the bottom C2 3 Model Capabilities STFATE enables the computation of the physical fate of dredged material disposed in open water The following discussion describes particular capabilities or special features 2 3 1 Disposal Methods Disposal is assumed to occur from either a split hull barge or a hopper dredge 2 32 Ambient Environment As illustrated in Figure C 2 time invariant velocity profil
44. ant is the one that requires the greatest dilution which will define the boundary of the mixing zone If mixing evaluations are conducted for toxicity test results the background concentration of dredged material is assumed to be zero and the percentages of dredged material are used to calculate the required dilution Use receiving water depth and velocity data to calculate a lateral mixing coefficient This coefficient is a measure of how rapidly the effluent is dispersed through the receiving water Calculate mixing zone length Check assumptions that depend on mixing zone length Calculate the maximum width of the mixing zone Step 1 Assumptions In order to apply the analytical solution described in this section the following assumptions are required C 63 a No major change in cross sectional shape sharp bends major inflows or outflows or obstructions to flow exist in the receiving water body in proximity to the mixing zone b The receiving water body can be reasonably approximated by a shallow rectangular cross section c The confined disposal area effluent enters the receiving water as a point source at the bank with negligible horizontal momentum d Differences in density between the effluent and receiving water and in settling rates of suspended particles within the boundary of the mixing zone are negligible e The flow condition in the vicinity of the mixing zone can be approximated as a steady state velocity fl
45. ations for calculating mixing zone size resulting from a single point discharge are presented A schematic illustrating a typical single source effluent discharging into a receiving water body is shown in Figure C 18 For such a condition the mixing zone length extends downstream and the body of the mixing zone remains close to the shoreline of the receiving water body RECEIVING WATER OUTFALL DREDGED MATERIAL WEIR CONTAINMENT AREA Figure C 18 Schematic of a Mixing Zone for a Single Effluent Source 4 2 62 Data Requirements The following data are required for evaluating mixing zone sizes for confined disposal area effluents C4 3 Step 1 Step 2 Step 3 Step 6 Effluent concentrations at the point of discharge and receiving water background concentrations for all contaminants of concern Water quality standards applicable at the limit of the allowable mixing zone for all contaminants of concern Depth cross sectional area and current velocity of the receiving water body during expected low flow conditions during the period of dredging Effluent volumetric flow rate Calculation Procedure Verify that the assumptions on which the equations depend are reasonable for conditions at the proposed discharge site Use effluent receiving water and water quality standard concentrations of all contaminants of concern to identify the critical contaminant critical contamin
46. ave length of 623 ft 190 m and a maximum width of 10 7 ft 3 3 m it 1s within the allowable limits of 750 ft 228 6 m from the effluent outfall C 72 C5 0 FASTTABS MODELING SYSTEM FOR EVALUATION OF HYDRODYNAMIC TRANSPORT Rivers reservoirs and estuaries have been modeled for a number of years using the USACE TABS numerical modeling system TABS is a family of two dimensional numerical models that simulate hydrodynamic sediment and constituent transport processes in these water bodies TABS has been used to simulate far field dispersion of instantaneous and continuous dredged material discharges Some independent near field analysis is usually required TABS can handle complex geometries and unsteady flow conditions Either particulate or dissolved phases of dredged material can be modeled The TABS system consists of many separate programs that individually address different aspects of the modeling process Thomas and McAnally 1990 These include mesh development geometry input file generation boundary condition definition hydrodynamic input file generation job status monitoring and post processing of the results A new graphical implementation of TABS FastTABS Lin et al 1991 has been developed that successfully addresses the need for efficient model setup execution and analysis It is mouse driven with pull down menus and requires a minimum of manual data entry to complete an application from start to finish
47. based on dilution needs More detailed descriptions and guidance for selection of values for many of the parameters is provided directly online in the system C2 5 Model Output The output starts by echoing the input data and then optionally presenting the time history of the descent and collapse phases In descent history the location of the cloud centroid the velocity of the cloud centroid the radius of the hemispherical cloud the density difference between the cloud and the ambient water the conservative constituent concentration and the total volume and concentration of each solid fraction are provided as functions of time since release of the material Table C 2 STFATE Model Input Parameters Parameter Contaminant Selection Data Solids concentration of dredged material Contaminant concentration in the bulk sediment Contaminant concentration in the elutriate Contaminant background concentration at disposal site Contaminant water quality standards Site Description Number of grid points left to right Number of grid points top to bottom Spacing between grid points left to right Spacing between grid points top to bottom Constant water depth Roughness height at bottom of disposal site Slope of bottom in x direction Slope of bottom in z direction Number of points in density profile Depth of density profile point Density at profile point Salinity of water at disposal site Temperature of water at disposal site
48. cient CM 1 0 Drag coefficient CD 0 5 Form drag collapse cloud CDRAG 1 0 Skin friction collapse cloud CFRIC 0 01 Drag ellipse wedge CD3 0 1 Drag plate CD4 1 0 Friction between cloud and bottom FRICTN 0 01 4 3 Law horizontal diffusion coefficient ALAMDA 0 001 Unstratified vertical diffusion coefficient AKYO 0 025 Cloud ambient density gradient ratio GAMA 0 25 Turbulent thermal entrainment ALPHAO 0 235 Entrainment collapse ALPHAC 0 1 Stripping factor CSTRIP 0 003 Concluded C 33 appears on the computer monitor Now the entering of the input given in Table C 3 developed from Table C 2 begins C2 8 1 1 1 Site Description Data Fl Site Description is selected from the STFATE Input Selection Menu by pressing key F1 or by using arrow keys to highlight the selection and pressing ENTER The number of grid points is selected as 32 in both the x direction top to bottom and z direction left to right The spacing is picked as 50 ft in the z direction and 150 ft in the x direction These spacings are selected since the velocity described later is 0 5 ft s in the x direction and 0 0 ft s in the z direction Thus the disposal site Fig C 5 is 1550 ft wide and 4650 ft long In the first screen of data entry the constant water depth is entered as 40 ft and the bottom roughness is input as the mid range value of 0 005 The bottom is assumed to be flat so a slope of zero is entered for the x and z directions Da
49. clay or lead and then selecting the depth desired 15 39 or peak in this example The user may select default contours YES or specify the desired contours NO Selecting NO to specify contours and then pressing PAGE DOWN the desired contours are entered sequentially on the next screen The water quality standards will already C 43 BARGE DUMP WITHOUT SPECIFIED MIXING ZONE TIER II W Q 8 048 LEAD PEAK FT C 8 032 0 N C g H24 8 816 n g I 6 688 A 6 608 1 1 1 1 1 1 1 1 1 1 1 1 1 B 8 16 24 32 48 48 56 64 TIME minutes x MAX CONC ON GRID STANDARD Figure C 8 Peak Lead Concentration in Water Column as a F Time for the Barge Disposal Example be specified when the mixing zone contaminant or fluid is selected for display Figure C 9 shows contours of concentrations of lead above background at a depth of 15 ft after 3600 s The contour values are specified for contours 1 2 and 3 as 0 0032 0 0001 and 0 00005 mg L As shown contour 1 is not displayed in Figure C 9 indicating the concentration value of 0 0032 mg L above background which is the water quality standard entered in the input file is not exceeded on the grid For this example the input requested that the mixing zone be predicted Figure C 10 shows the predicted peak mixing zone outside of which the 0 0032 mg L standard is not exceeded during the simulation at any depth plot the predicted mixing zone press the F2 key from the STFATE Grap
50. cted by opposite bank of the receiving water body as long as where W surface width of receiving water channel m Step 6 Estimate maximum width of mixing zone maximum width of the mixing zone measured perpendicular to the bank as shown in Figure C 18 can be estimated as 0 4840Q C u C Cd where Y maximum width of the mixing zone m C4 4 Example Mixing Zone Calculation Following is a hypothetical mixing zone calculation designed to illustrate the use of the mixing zone estimation equations A proposed dredged material containment area is expected to discharge into a river 480 ft 146 3 m wide From a study of US Geological Survey stream gage records it is anticipated that while effluent will be discharged the lowest river flow will be about 7 600 ft sec 212 8 m sec and that the river has a cross sectional area of 4 000 ft 371 6 m at this flow rate The local bed slope of the river is known to be very variable due to sediment transport The containment area is expected to have a peak discharge of 15 cfs The only effluent contaminant that exceeds water quality standards will be cadmium which is expected to have an effluent concentration of 3 5 ug L The background concentration of cadmium in the river is below the detection limit of 0 1 ug L and the applicable cadmium water quality standard is 0 25 ug L It has been specified that the maximum acceptable mixing zone size is a 750 ft 228 6 m radius center
51. d Typically this is not necessary and NO is selected as was done for the example The final screen for material description requests input on the density of the dredging site water which is in the barge with the dredged material solids For the example the density is entered directly YES to first question and the value of 1 000 g cc is accepted If the density is different it can be entered in the highlighted box If salinity and temperature data only are available then NO is selected and another screen will appear to allow for the input of those data At this point PAGE DOWN is pressed which brings back the STFATE Input Selection Menu C2 8 1 1 5 Disposal Operation Data To describe the disposal operation F5 Disposal Operation Data is selected which brings up a screen requesting input concerning location of disposal point length and width of barge bin the barge draft before and after disposal and the time needed to empty the barge The actual data are entered into the respective highlighted boxes on the screen this example the location of the disposal point in distance from the top of grid of 1000 ft and from the left edge of grid of 750 ft are entered The length and width of barge bin are entered as 200 and 50 ft respectively The pre and post disposal draft are entered as 17 ft and 5 ft and the time to empty barge is 20 s Pressing PAGE DOWN gets the next screen which requests information concerning disposal in a pre existing
52. d contaminants The contaminant requiring the largest dilution should be subsequently modeled in the Tier II water quality analysis Contaminant Data File Saving Menu This menu has the same structure as the Input File Saving Menu see step j The contaminant data files are saved with an extension of DUD The contaminant data files store the user specified data including contaminant names particulate associated concentrations of contaminants in the bulk sediment sediment solids concentration standard elutriate concentrations of contaminants water quality standards for the contaminants and concentrations of contaminants in the background water at the disposal site Input Data File Selection Menu Selecting F3 from the Evaluation Selection Menu brings up the Input Data File Selection Menu An input data file needs to be selected only when the user wants to edit data that were previously entered The changes can be saved to the same file or to a new file The first option is used to specify the name of the file to be used The file specified in this option becomes the active data file If needed the second option is used to specify the DOS path to the location where the data file should be read If a path is not specified the program will use the default directory where the STFATE program is for file storage The third option displays a directory of STFATE input data files for the current path that is files having an extension of DUI in
53. data and output will occur These methods of ending are not recommended Similar methods are available during printing of output C2 8 STFATE Application Examples Two example applications of the use of the numerical model STFATE are described first example addresses the instantaneous disposal of dredged material from a split hull barge or scow These barges or scows may hold anywhere from approximately 400 to 6000 yd of material and 30 dispose of the material by means of opening the split hull and discharging the material through the bottom opening The material then descends through the water column to the bottom of the water body The second example illustrates the modeling of dredged material disposal from a multiple bin hopper dredge hopper dredge fills its bins with dredged material and then transports it to the disposal site where it discharges the material Each bin has a separate opening in the ship s bottom through which the dredged material is discharged into the water column Typically there are anywhere from about 4 to 20 bins in a hopper dredge which can carry a total of approximately 1000 to 9000 yd of material During disposal one or more bins are opened sequentially until all of the bins have been emptied The required input data for both examples are described and the results or output from the STFATE model are illustrated and discussed Additionally the input and output files for each of the examples are includ
54. define the TSS concentration corresponding to the water quality standard for turbidity Step 3 Estimate of lateral mixing coefficient Step 3 1 The depth of a simplified rectangular cross section for the receiving water body should be calculated as follows 64 a 4 W where d average depth of the receiving water body channel m A cross sectional area of the channel m W surface width of the channel m Check to ensure that W 15 equal to or greater than 10 times the average depth d If not the estimate of a lateral mixing coefficient is likely to be inadequate Step 3 2 Estimate the shear velocity by one of the following methods In rivers where the mean channel slope is known use vgds In rivers where the channel slope is not known use where u shear velocity in receiving water m sec g gravitational acceleration 9 81 m sec d average channel depth m slope of river bed dimensionless u average of instantaneous velocities across the channel cross section m sec If the flow rate of the receiving water is known u can be calculated as the flow rate divided by the channel cross sectional area If the receiving water flow rate is not known u must be determined from velocity measurements taken at the proposed site It should be noted that u should not be determined over a period of time during which velocity changes occur due to changes in the receiving water flow rate Step 3
55. depression For the example no depression is used and the values of zero are accepted PAGE DOWN is pressed again completing data entry and returning to the STFATE Input Selection Menu C2 8 1 1 6 Coefficients The STFATE Input Selection Menu is now displayed on the monitor and the next selection is F6 Coefficients Default Values Highlighting this selection and pressing ENTER or pressing F6 shows the numerical model coefficients In most cases the absence of calibration data the default values should be chosen and this is done in the example by pressing PAGE DOWN If other values are required then enter them in the highlighted box before pressing PAGE DOWN Expert guidance should be obtained before using coefficient values other than the default numbers C2 8 1 1 7 Saving Input Data Menu Data entry is now complete as indicated by asterisks by each data entry option The next step is to save the input data file for use in the execution of STFATE To proceed press the F7 key or select F7 Saving Input Data Menu from the STFATE Input Selection Menu and press ENTER The Saving Input Data Menu appears and requests input as to whether a new file name is desired or the active data file should be used for storing the data The file name entered at the beginning of the input process appears as the active data file To save the data or changes in the active data file select option F4 Save data in or to the active data file For th
56. e bottom are not discussed since the emphasis is on results for water column concentrations for Tier II and III evaluations However bottom sediment accumulation output is contained in the BARGE DUO file in the STFATE model Output related to the convective descent and collapse phase is also contained in the output file for the barge example BARGE DUO for information purposes The results discussed are water column concentrations of the solids fractions contaminant and the fluid associated with the dredged material in the barge Results are in the form of tabular output and graphical presentations which can be accessed through the STFATE Activity Selection Menu This screen provides two options for output F3 Print or view output and F4 Generate graphics If option F3 is selected the STFATE Output Data File Selection Menu appears and it provides several possibilities First the option Fl Enter name of 38 data used during execution is used and for this example the filename is entered after selecting this option Once the filename is identified the options F4 Print selected output file or F5 View selected output file are used There is considerable model output and all of the output is usually not desired The F5 option provides viewing of the output file by paging through it using the PAGE UP and PAGE DOWN keys The viewing software can also be used to select specific portions of the output for printing select
57. e receiving water boundaries Since the maximum allowable mixing zone specified by regulatory agencies is usually on the order of hundreds of meters the evaluation of mixing zone sizes must necessarily be based on calculation of near field dilution and dispersion processes There are a variety of possible estimation techniques for most real mixing zone problems but any choice of a suitable technique involves some tradeoffs The available techniques may be thought of as ranging from sophisticated computer models which are sometimes capable of very accurate predictions to simple approximations that yield order of magnitude estimates The most sophisticated models may not run on a microcomputer and they may require a considerable amount of measured 2 data and personpower for calibration of the model to a single site By contrast the simplest of approximations may be made on the basis of several simplifying assumptions and hand calculations C1 2 Regulatory Considerations Any evaluation of potential water column effects has to consider the effects of mixing Section 230 3 m of the Guidelines defines the mixing zone as follows The term mixing zone means a limited volume of water serving as a zone of initial dilution in the immediate vicinity of the discharge point where receiving water quality may not meet quality standards or other requirements otherwise applicable to the receiving water The mixing zone should be cons
58. ed hard copy Pressing the ESC key returns the STFATE Activity Selection Menu C2 8 1 2 1 Barge Disposal Water Column Concentrations and Area Distribution In this example water column concentrations of the solids fraction and the contaminant were requested at 15 and 39 ft Thus the concentrations for clumps sand clay and lead at every grid point location for both depths are contained in the output file addition results are available showing the maximum concentration occurring at each grid point over the depth of the water column for the duration of the simulation The top section of Figure C 7 shows the output for lead concentration in mg L at 15 ft at the end of the model run 3600 s The concentration values at each grid point are must be multiplied by the appropriate scale factor shown at top of the table to get actual concentration In this example the maximum value on the grid is 1 6 which is multiplied by 0 001 yielding a maximum lead concentration of 0 0016 mg L at x and z grid locations of 20 and 16 respectively Recall from the input that the distance between x grid points is 150 ft and between z grid points is 50 ft Therefore the maximum concentration occurs 2850 ft from top of grid and 750 ft from left edge of grid The disposal began at an x and z distance of 1000 ft grid point 8 and 750 ft grid point 16 Both the barge and water velocity were in the positive x direction so it is reasonable to find the maximum concen
59. ed on an executable version of the STFATE model which can be downloaded from the Internet web site http www epa fov OST pubs ITM html see section C2 6 2 C2 8 1 Split hull Barge or Scow Example An example of dredged material disposal is modeled for an instantaneous disposal using STFATE for a 3000 yd disposal from a split hull barge at a constant 40 ft depth site for Section 404 b 1 regulatory analysis for water quality The input data for this example are given in Table C 3 No mixing zone dimensions are specified for this example therefore the dimensions of a mixing zone required to meet the water quality standard are calculated description follows for entering the required example data and the use of the STFATE module C2 8 1 1 Entering STFATE and the Input Data File Selection Menu The STFATE model is executed from the disk operating system DOS prompt and the STFATE Activity Selection Menu is reached as presented earlier The menus are shown in Figs C 3 and C 4 To proceed the Build or edit input data file option is selected and the STFATE Short term Fate of a Disposal in Open Water Evaluation Selection Menu appears For this example the option Section 404 b 1 Reg Analysis for Navigable Waters is selected Next the STFATE Input Data File Selection Menu is presented and the key F1 is pressed to enter name of input data file to be built or edited For this example BARGE is typed and the ENTER key is pressed Optio
60. ed on the effluent outfall 67 Step 1 Assumptions Since the purpose of this hypothetical problem is to demonstrate the use of the mixing zone calculations it has been defined so that all the assumptions on which the calculations depend are valid Decisions on whether the assumptions are valid depend largely on the professional judgement of personnel familiar with the disposal site Step 2 Identify critical contaminant Cadmium 15 the only effluent contaminant that exceeds water quality standards for this example It is therefore unnecessary to determine the critical contaminant Step 3 Estimate lateral mixing coefficient Step 3 1 From the problem statements 4 000 ft 371 6 m W 480 ft 146 3 m Calculate depth from equation 2 xm 2 a 346m 554m 146 3 m Check that W gt 10d It is Step 3 2 Since the local bed slope is known to vary due to sediment transport the shear velocity should be estimated from the mean velocity Calculate the mean velocity by dividing the river flow of 7 600 ft sec 212 8 m sec by the cross sectional area of 4 000 ft 371 6 m 2800 d _ 199 0 579 mjsec 1 4 000 ft 68 and calculate the shear velocity of the receiving waters as follows 0 1 0 579 0 0579 m sec Step 3 3 In rivers the lateral mixing coefficient should be estimated as E 0 3 d ux E 0 3 2 54 m 0 0579 m sec E 0 0441 m7 sec
61. eir The effluent suspended solids concentration is typically less than 100 mg L for sediments dredged from estuarine environments and less than a few grams per liter for sediments dredged from freshwater environments C 6 1 5 Applicability of Models and Techniques C1 5 1 General Considerations Equations can be derived from a simplistic approach to the problem of estimating mixing zone size that make it possible to use a combination of empirical and analytical solutions However the simplifications that make the calculations easily manageable are somewhat restrictive and a more advanced set of similar empirical and analytical solutions could be used to estimate mixing zone sizes under more complex conditions more advanced analytical solutions involve many more computations and for this reason they are more easily dealt with by use of a computer simplicity and limited data requirements of analytical solutions make them an attractive tool How ever analytical solutions cannot be used for receiving water where there are complex hydrodynamic conditions nor can they be applied under dynamic unsteady flow conditions Where these conditions exist a numerical model must be used and numerical dispersion models are not susceptible to hand calculation In addition to requiring a computer solution technique numerical models generally require a much more detailed set of input data and the collection of such data can be expensive
62. election Menu F1 Enter name of data file used during execution F2 Enter DOS path for data file storage location Optional F3 Display directory of graphics data files F4 Generate graphics with selected file Esc Return to STFATE Activity Selection Menu STFATE Graphics Generation Menu F1 Maximum Concentrations versus time F2 Concentration contours in horizontal plane F3 Deposition thickness at end of simulation Esc Return to STFATE Graphics File Selection Menu 24 STFATE Evaluation Selection Menu F1 General Open Water Disposal Analysis F2 Section 103 Regulatory Analysis for Ocean Waters F3 Section 404 b 1 Reg Analysis for Navigable Waters FA Determine Contaminant of Concern Based on Dilution Needs Esc Return to STFATE Activity Selection Menu STFATE Input Data File Selection Menu STFATE Contaminant Data File Selection Menu F1 Enter name of input data file to be built or edited F2 Enter DOS path to data file storage location Optional F3 Display directory of input data files F4 Build or edit input data file Esc Return to STFATE Activity Selection Menu F1 Enter name of data file to be built or edited F2 Enter DOS path to data file storage location Optional F3 Display directory of contaminant data files F4 Build or edit contaminant data file Esc Return to STFATE Evaluation Selection Menu F4
63. epths of 0 10 20 30 and 40 ft The simulation 54 CONCENTRATIONS ABOVE BACKGROUND OF FLUID VOLUMETRIC RATIO OF DUMP FLUID TO AMBIENT WATER IN THE CLOUD 3600 00 SECONDS AFTER DUMP 20 00 FT BELOW THE WATER SURFACE MULTIPLY DISPLAYED VALUES BY 0 1000E 01 LEGEND 01 0001 0 11 000001 MN 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 3031 2 OO000000000000000000000000000000000000000000000000000000000000000000000000000000000 30000 0 000000000000000000000000000 40000 0 0 0 0 0 0 0 0 0 0 0 O 00 OOOO 50000 0 0 0 0 0 0 0 0 00 0 0 60000 0 0 0 0 0 0 0 0 0 00 0 0 70000 0 0 0 0 0 0 0 0 0 0 0 00 0 0 80000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 00 0 0 90000 0 0 0 0 0 0 0 0 0 0 00 0 0 100000 0 0 0 0 0 0 0 0 0 0 0 0 0 O 110000 0 0 0 0 0 0 0 0 0 0 0 0 O 120000 0 0 0 0 0 0 0 0 0 0 0 0 O 130000 0 0 0 0 0 0 0 0 0000 140000 0 0 0 0 0 0 0 O 150000 0 0 0 0 0 0 0 0
64. es that allow for flow reversal can be prescribed These profiles are applied at each grid point Another option is to specify a time invariant spatially varying depth averaged velocity The ambient density profile at the deepest point on the grid must also be prescribed 4 CI ww 40 ji Dw2 Figure C 2 Velocity Profile Available for Use in PC Model C2 3 3 Time varying Fall Velocities If a solid fraction is specified as being cohesive the settling velocity is computed as a function of the suspended sediment concentration of that solid type The algorithm used is 0 000034 if C lt 25 mg L V 0 0000225 1 6 x 107 if 25 lt C lt 3000 mg L 0 0069 if C gt 3000 mg L 9 where V settling velocity fps C suspended sediment concentration mg L This approach is taken from Ariathurai et al 1977 17 2 3 4 Conservative Constituent Computations STFATE allows for the dredged material to contain a conservative constituent with perhaps a nonzero background concentration of that constituent Computing the resultant time history of that concentration provides information on the dilution that can be expected over a period of time at the disposal site and enables the computation of mixing zones in water column evaluations C2 4 Model Input Input data for the model are grouped into the following general areas 1 description of the disposal site 2 description of site velocities 3 controls for
65. es that might be suitable for inclusion as submodels in a general mixing zone model Sources that presently seem to present the most promising empirical and analytical solutions to these sub model processes are also presented in the tabulation C 7 Physical Process to be Handled by a Submodel Source Momentum and or buoyancy dominated jets Zeller et al 1971 Motz and Benedict 1972 Buhler and Hauenstein 1981 Jirka et al 1981 Wright 1984 Doneker and Jirka 1990 3 dimensional dispersion in receiving water Prakash 1977 Fischer et al 1979 Johnson et al 1994 King 1992 2 dimensional vertically averaged dispersion Stefan and Gulliver 1978 Paily and Sayre 1978 Gowda 1984a b Thomas and McAnally 1990 C1 5 2 Considerations for Tidally Influenced Rivers and Estuaries The assumptions necessary for evaluation of mixing are more difficult to satisfy in estuaries and the tidally influenced portions of rivers The assumption that velocities in the water body near the mixing zone can be represented by a single mean velocity parallel to the bank is usually a reasonable one in the non tidally influenced portion of a river However it is not always acceptable in estuaries Typically the downstream section of an estuary exhibits horizontal circulation patterns so that the horizontal water velocity and direction vary with distance parallel to the bank distance perpendicular to the bank and time Under these conditions wate
66. evelopment Center for Exposure Assessment Modeling CEAM Athens Environmental Research Laboratory 960 College Station Road Athens Georgia 30605 2720 CORMIX can be either downloaded from CEAM s on line Bulletin Board System by calling 1 706 546 3402 FTS 250 3402 or sent through the mail by sending user supplied diskettes or 9 track magnetic tapes to the CEAM Model Distribution Coordinator at the above address User documentation is also available from the same source 61 4 0 MACINTYRE ANALYTICAL METHOD FOR CDF DISCHARGE IN RIVERINE CONDITIONS Introduction This section presents a simplified approach that is applicable to relatively shallow confined riverine water bodies method involves a simplistic two dimensional calculation based on dispersion principles MacIntyre 1987 If the mixing zone size as calculated using simple approximations is within mixing zone guidelines specified by regulatory agencies more precise calculations may not be necessary The mixing zone calculations depend on a number of assumptions that are difficult to satisfy for estuaries and the tidally influenced portions of rivers The difficulties are discussed after the presentation of the procedure to be used for a riverine environment The analytical solution technique for calculating mixing zone size described in this section is based on theoretical and empirical relationships for dispersion as summarized by Fischer et al 1979 Only equ
67. ft 0 0 Contaminant Lead WQ standard at edge of mixing zone mg l 0 0032 Predicted initial concentration in fluid mg L 0 174 Background concentration mg L 0 0002 Number of depths for output 2 Depths for output ft 15 39 Continued C 32 Table C 3 continued STFATE Input Variables for Section 404 b 1 Regulatory Analysis of Navigable Waters Using a Scow Barge Disposal INPUT PARAMETER UNITS INPUT VALUE MATERIAL DESCRIPTION Number of solids fraction 3 Solid fraction descriptions clumps sand clay Solid fraction specific gravity 1 6 2 7 2 65 Solid fraction volume concentration yd yd 0 1 0 2 0 05 0 0 0 15 0 10 Solid fraction fall velocity ft s 3 0 0 1 0 002 Solid fraction depositional void ratio 0 4 0 6 5 0 Solid fraction critical shear stress lb ft 99 0 025 0 002 Cohesive Y N N N Y Stripped during descent Y N N Y Y Dredge site water density g cc 1 0 Number of layers 2 Volume of each layer yd 2000 1000 Vessel velocity in x direction ft s 6 6 Vessel velocity in z direction ft s 0 0 DISPOSAL OPERATION Disposal point top of grid ft 1300 Disposal point left edge of grid ft 750 Length of vessel bin ft 200 Width of vessel bin ft 50 Bottom depression length x direction ft 0 Bottom depression length z direction ft 0 Bottom depression average depth ft 0 Predisposal draft ft 17 Postdisposal draft ft 5 Time to empty vessel 5 20 COEFFICIENTS Settling coef BETA 0 0 Apparent mass coeffi
68. gure C 17 Plot of Required Mixing Zone for the Hopper Disposal Example 60 C3 0 CORNELL MIXING ZONE EXPERT SYSTEM CORMIX The Cornell Mixing Zone Expert System CORMIX is a steady state three dimensional model Doneker and Jirka 1990 CORMIX was developed to predict the dilution and trajectory of a submerged single port discharge of arbitrary density positive neutral or negative into a stratified or uniform density ambient environment with or without cross flow CORMIX is an integral model that accounts for most near field and some far field steady state dynamics CORMIX is presently designed for use in shallow water systems where the jet mixing processes are expected to encounter bottom boundary interaction is capable of representing negatively buoyant plume dynamics through application of mirroring principals however the present version does not include sediment settling and deposition The current version of the CORMIX model requires some modifications to extend its capabilities to simulate the characteristics of dredged material discharges Efforts are underway for adaptations of the CORMIX model for simulating the mixing hydrodynamics of several types of dredged material discharges When these efforts are completed the revised CORMIX model will be included in subsequent revisions of this appendix The latest release of CORMIX Version 3 2 can be obtained without charge from U S EPA Office of Research and D
69. he effect of the sediment of the water column The maximum value of K is input as a model coefficient and occurs when the water density is uniform It should be noted that since computations are made for each solid fraction independently from the remaining material the effect of the total volume of suspended material on reducing vertical diffusion is not modeled This can sometimes lead to confusing results e g a small amount of sand may become diffused over the entire water column while a much larger amount of silt might have its vertical diffusion suppressed due to the larger concentration Modifications to correct this problem are under investigation If long term output is desired at the end of a particular time step the concentration of each solid type is given at each grid point by summing the contributions from individual clouds to yield 8 E z j Zo n 2 2 0 where N is the number of small clouds of a particular solid type and the vertical position at which output is desired is specified through input data This approach for the transport diffusion phase follows the work of Brandsma and Sauer 1983 The surface and all solid boundaries except the bottom are handled by assuming reflection from the boundaries In addition to the horizontal advection and diffusion of material settling of the suspended solids also occurs Therefore at each net point the amount of solid material deposited on the bottom and
70. hics Generation Menu which displays a new screen Now select the box Mixing and the desired depth Press PAGE DOWN to receive the next screen and select time and whether defaultcontours are used In this example choose NO and press PAGE DOWN The following screen requests user specified contour values Insert contour values and press PAGE DOWN to receive graph This completes the example and the ESC key is pressed repeatedly to return to the STFATE Activity Selection Menu or to quit the program and return to DOS prompt 44 BARGE DUMP WITHOUT SPECIFIED zOHE TIER 4 5 1 LEAP B FT X COH TINI VALUES iu 22BE B C i BHE Bi T 3 4 SHEE H Z BIEECEIOH Figure C 9 Lead Concentration Contours for 15 ft Depth at 3600 sec for the Barge Disposal Example BARGE DUMP WITHOUT SPECIFIED MIXING ZONE TIER II U Q MIXING B MG L 3688 SEC i200 p I R CONTOUR VALUES 2488 1 3 2BBE B3 T I 0 N 3608 4800 1600 2 DIRECTION Figure C 10 Plot of Required Mixing Zone for the Barge Disposal Example 45 2 8 2 Multiple bin Hopper Dredge Example An example of dredged material disposal is modeled using STFATE for a 3000 yd disposal from a hopper dredge at a constant 40 ft depth site for Section 404 b 1 regulatory analysis for water column toxicity mixing zone is specified for this example therefore the calcula
71. idered as a place where wastes and water mix and not as a place where wastes are treated Further Section 230 11 f requires that C1 3 The mixing zone shall be confined to the smallest practicable zone within each specified disposal site that is consistent with the type of dispersion determined to be appropriate by the application of these Guidelines In a few special cases under unique environmental conditions where there is adequate justification to show that widespread dispersion by natural means will result in no significantly adverse environmental effects the discharged material may be intended to be spread naturally in a very thin layer over a large area rather than be contained within the disposal site Potential Applications of Initial Mixing There are three potential applications of initial mixing evaluations a b screen to determine the need for additional water column testing under Tier II evaluate dissolved contaminant concentrations by comparison with water quality standards after allowance for mixing under Tier II evaluate concentrations of suspended plus dissolved constituents by comparison with toxicity test results after allowance for mixing under Tier III C 3 C1 3 1 Screen to Determine Need for Additional Water Column Testing The screen determines the necessity for additional water column testing This determination is based on a standardized calculation comparing the bulk contaminatio
72. ified ambient water column the same conservation equations used in convective descent but now written for either an oblate spheroid or an ellipsoid are applicable For the case of collapse on the bottom a frictional force between the bottom and the collapsing cloud is included which accounts for energy dissipation as a result of the spreading Other than the changes noted above the same equations presented in Brandsma and Divoky 1976 apply C2 2 3 Transport diffusion When the rate of spreading in the dynamic collapse phase becomes less than an estimated rate of spreading due to turbulent diffusion in both the horizontal and vertical directions the collapse phase is terminated Laboratory experiments by Johnson et al 1994 as well as field data collected by Kraus 1991 imply that fine material is lost to the water column at the top of the collapsing cloud As these 13 particles leave the main body of material they are also stored in small clouds that are characterized by a Gaussian distribution 1 e lt 2 e 2 w 2 _ 6 2 1 2 7 o 7 X y 7 where m volume of solids in the cloud ft 0 0 0 standard deviations ft spatial coordinates ft X Y Z coordinates of cloud centroid ft At the end of each time step each cloud is advected horizontally by the input velocity field The new position of the cloud centroid is determined by X X u A
73. input execution and output 4 description of the dredged materials 5 description of the disposal operation and 6 model coefficients Ambient conditions include current velocity density stratification and water depths over a computational grid The dredged material is assumed to consist of a number of solid fractions a fluid component and conservative dissolved contaminants Each solid fraction has to have a volumetric concentration a specific gravity a settling velocity a void ratio for bottom deposition critical shear stress and information on whether or not the fraction is cohesive and or strippable For initial mixing calculations information on initial concentration background concentration and water quality standards for the constituent to be modeled have to be specified description of the disposal operation includes the position of the disposal barge or hopper dredge on the grid the barge or hopper dredge velocity dimensions and draft the volume of dredged material to be discharged Coefficients are required for the model to accurately specify entrainment settling drag dissipation apparent mass and density gradient differences These coefficients have default values that should be used unless other site specific information is available Table C 2 lists the necessary input parameters with their corresponding units Table C 2 also lists the input parameters for determining the contaminant of concern to be modeled
74. is example the active data file BARGE is selected If the active data file exists the program indicates the active data file already exists and requests to overwrite the file Therefore Y is entered to overwrite and the program then requests the entering or editing of a descriptive title for the file For this example the title Barge dump without specified mixing zone Tier II W Q is entered Sometimes a file is being edited but the original data file needs to be kept unchanged At this point a new file name can be selected using Fl Enter name of file to be saved the changes are then saved using option F4 After the data are saved the STFATE Input Selection Menu reappears and all of the selections show an asterisk indicating each selection has been completed The final step of the input process is to press ESC and return to the SFTATE Activity Menu which is the screen at which the input process began Once the input file is complete and saved the STFATE model can be executed by first selecting F2 Execute STFATE which then requests the input data file to be input BARGE is input to obtain results for this example which are discussed in the next section C2 8 1 2 Description of Barge Disposal Example Output A general description of the output available from the STFATE has been described The objective in this section is to illustrate and describe selected portions of the results The results concerning the accumulation of sediment on th
75. ivity Selection Menu 53 C2 8 2 2 1 Hopper Disposal Water Column Concentrations and Area Distribution In this example water column concentrations of the solids fractions and the fluid volume ratio volume of dumped fluid volume of ambient water are requested at 20 and 39 ft Thus the concentrations for sand silt clay and the fluid at every grid point location for both depths are contained in the output file provided the material has not settled to the bottom In addition results are also available showing the maximum concentration occurring at each grid point for anywhere in the water column as well as at the requested depths throughout the duration of the simulation The top portion of the selected output shown in Figure C 14 shows the output for fluid volume ratio volume of fluid from the discharge volume of water column at the grid point at 20 ft at the end of the model run 3600 s These values at each grid point are multiplied by the appropriate scale factor 0 01 as given at the top of the output These values would be multiplied by 100 if the results were desired with units of percent In this example the maximum value on the grid is 1 6 which is multiplied by 0 01 yielding a maximum fluid volume ratio of 0 016 at x and z grid locations of 21 and 16 respectively Recall from the input that the distance between x grid points is 150 ft and between z grid points is 50 ft Therefore the maximum concentration occurs 3000 ft from top of g
76. lts for this example which are discussed int the next section C2 8 2 2 Description of Example Hopper Disposal Output The objective of this section is to illustrate and describe selected portions of the hopper dredge disposal results Accumulation of sediment on the bottom is not discussed since the emphasis is on results for water column concentrations for Tier II and III evaluations The results discussed are concentrations of the solids fractions contaminant and the fluid associated with the dredged material in the hopper bins As previously explained in the barge example results are accessed through the STFATE Activity Selection Menu This screen provides two options for output F3 Print or view output and F4 Generate graphics If option F3 is selected the STFATE Output Data File Selection Menu appears and provides several possibilities First the option F1 Enter name of data file used during execution is used and the filename HOPPER is entered after selecting this option Once the filename is entered the options F4 Print selected output file or F5 View selected output file can be used There is considerable output from the model and all of the output is usually not desired The F5 option provides viewing of the output file by paging through it using the PAGE UP and PAGE DOWN keys The viewing software can be used to select specific portions of the output for printing a hard copy Pressing the ESC returns the STFATE Act
77. n An input data file may be written at any point to save all the data that have been entered up to that point After entering all of the data the data must be saved before returning to the STFATE Activity Selection Menu to avoid losing the changes The data are saved in input data and execution data files by selecting F7 from the Input Selection Menu to bring up the Input File Saving Menu Input File Saving Menu This menu provides the opportunity to write an input data file to save the input data for future editing under the STFATE Input Selection Menu and an execution data file for use during execution of the STFATE model Execution data files are the actual input data files used by the open water disposal model to perform the analysis and generate output These files are unique in structure to the input requirements of a particular open water disposal operation and contain data only for the specific options selected in the input The files are stored with the same name as the input data file but with an extension of DUE instead of DUI The input data file stores data for all possible options in evaluations disposal operations and methods of data entry allowing the user to perform comparisons between options without re entering 28 previously specified data This menu is similar to the Input Data Selection Menu see step The only difference is that the name of the file to be saved instead of read should be specified The same file a
78. n F4 Build or edit input data file is then selected to read the input data file if it exists or to initialize it if it is a new file A descriptive title Barge dump without specified mixing zone Tier II W Q is typed and entered Press ENTER The Disposal Operation Selection Menu is presented next Disposal from a Split Hull Barge or Scow is selected and the STFATE Input Selection Menu 31 Table C 3 STFATE Input Variables for Section 404 b 1 Regulatory Analysis of Navigable Waters Using a Scow Barge Disposal INPUT PARAMETER UNITS INPUT VALUE SITE DESCRIPTION Number of grid points L R z dir 32 Number of grid points T B x dir 32 Grid spacing L R f V ft 50 Grid spacing T B f V ft 200 Constant water depth ft 40 Bottom roughness ft 0 005 Bottom slope x dir de 0 Bottom slope z dir de 0 Number of points in density profile 2 Density at point one surface cc 1 0000 Density at point two bottom cc 1 0002 VELOCITY Type of velocity profile 2 pt Water depth 2 point profile ft 30 38 Vel for 2 point x direction ft s 0 5 0 3 Vel for 2 point z direction ft s 0 0 INPUT EXECUTION amp OUTPUT KEYS Process to simulate Disp from Split Hull Barge Scow Duration of simulation S 3600 Time step for diffusion f V S 300 Convective descent output Yes Collapse phase output option Yes Number of print times for diffusion Quarterly Upper left corner mixing zone ft 0 0 Lower right corner mixing zone
79. n of the dredged material with water quality standards considering the effects of initial mixing This worst case approach assumes that all of the contaminants from the dredged material are released to the fluid fraction and subsequently to the water column Mixing evaluations need only be made for the contaminant requiring the greatest dilution to meet its water quality standard The key parameter derived from the evaluation is the maximum concentration of the contaminant in the water column at the boundary of the mixing zone This concentration is compared with the applicable water quality standard to determine if additional water column testing is necessary This evaluation cannot be used to predict water column impacts but only to determine the need for additional water column testing C1 3 2 Evaluation of Dissolved Contaminant Concentrations by Comparison with Water Quality Standards If additional water column testing is necessary the potential for water column impacts may be evaluated under Tier II by comparison of predicted dissolved contaminant concentrations as determined by an elutriate test with the water quality standards considering the effects of mixing This approach is used if there are water quality standards for all contaminants of concern if these conditions are not met the procedure in Section C1 3 3 is used mixing evaluation need only be made for the contaminant requiring the greatest dilution to meet its water quali
80. nd what to plot Either the screen printer or plotter must be selected and then the material sand silt clay or fluid and depth 20 39 or peak Peak means the depth at which the maximum concentrations or fluid ratio occur The maximum fluid ratio versus time in this hopper disposal example Fig C 15 shows the maximum percent 12 2 on the grid occurs about 5 min after disposal begins and it drops to just below 1 6 near the end of the simulation The maximum fluid percent outside the mixing zone defined in the input is initially below the toxicity standard 0 490 but the standard is violated at about 49 min after disposal begins and remains in violation for the remainder of the simulation Referring back to Figure C 14 it can be seen that the peak depth is 20 ft HOPPER DISCHARGE WITH SPECIFIED MIXING ZONE TIER III 14 FLUID PESK FT C 0 N jp C i 4 7 6 b 4 y 2 eras eia ere 8 8 16 24 32 4 5 64 TIME minutes Mz STANDARD Figure C 15 Peak Fluid Ratio as a F Time for the Hopper Dredge Disposal Example 58 Selecting option F2 Concentration contours in horizontal plane displays a screen which provides the ability to graphically display the percent fluid contours or the solids fraction concentration contours As before the graphs can be output to the screen plotter or printer The contours are obtained by selecting the solid fraction fluid or mixing zone and then
81. ng the models are presented Background Whenever contaminant concentrations in a dredged material discharge are above water quality stan dards there will be some limited initial mixing zone or zone of dilution in the vicinity of the dis charge point where receiving water quality standards may be exceeded Guidelines recognize that it is not possible to set universal standards for the acceptable size of mixing zones since receiving water conditions vary so much from one location to another The Guidelines therefore instruct that as part of the dredging permit process the size of any proposed mixing zone should be estimated and submitted to the permitting authority permitting authority must then consider receiving water conditions at the proposed site and decide if the proposed mixing zone size is acceptable Many state regulatory agencies may specify a limit to mixing zone dimensions as a condition in grant ing the State water quality certification In this case the mixing zone necessary to meet applicable standards must be smaller than the specified limits The size of a mixing zone depends on a number of factors including the contaminant or dredged material concentrations in the discharge concentrations in the receiving water the applicable water quality standards discharge density and flow rate receiving water flow rate and turbulence and the geometry of the discharge vessel pipeline or outlet structure and th
82. ngs of pairs of hopper bins and the velocity of the hopper dredge For this example there are three discrete openings of sets of two hopper bins Also the hopper dredge is assumed to travel at a constant 51 SET 3 HOPPER Sars DREDGE SET 1 FORWARD Figure C 13 Schematic of Hopper Dredge with 6 Bins In this example the bins are opened in sets of two bins 1 amp 2 bins 3 amp 4 and bins 5 amp 6 velocity of 6 ft s during all three discrete openings After entering these data and pressing PAGE DOWN the next screen requires data entry concerning disposal in a pre existing depression and for this example values of zero are accepted PAGE DOWN is pressed again and the STFATE Input Selection Menu reappears on the monitor C2 8 2 1 6 Coefficients The STFATE Input Selection Menu is now on the monitor and the next selection is F6 Coefficients Default Values Highlighting this selection and pressing ENTER pressing F6 displays the numerical model coefficients In most cases the default values should be chosen and this was done for the example by pressing PAGE DOWN If other values are required they may be entered in the appropriate highlighted box before pressing PAGE DOWN Expert advice should be obtained before using coefficient values different from the default numbers C2 8 2 1 7 Saving Input Data Menu The entering of data is now complete as indicated by the asterisks by each data entry option The next
83. ntal Protection Agency PA 600 3 90 012 Environmental Effects Laboratory 1976 Ecological evaluation of proposed discharge of dredged or fill material into navigable waters interim guidance for implementation of Section 404 b 1 of Public Law 92 500 Federal Water Pollution Control Act Amendments of 1972 Miscellaneous Paper D 76 17 U S Army Engineer Waterways Experiment Station Vicksburg MS 79 Fischer R et al 1979 Mixing in Inland and Coastal Waters Academic Press New York NY Gowda T P H 1984a Critical point method for mixing zones in rivers J Environ Engineer Am Soc Civil Engineers 110 244 262 Gowda T P H 1984b Water quality prediction in mixing zones of rivers J Environ Engineer Am Soc Civil Engineers 110 751 769 Jirka G H et al 1981 Buoyant surface jets J Hydraul Engineer Am Soc Civil Engineers 107 1467 1487 Johnson B H 1990 User s guide for models of dredged material disposal in open water Technical Report D 90 5 US Army Engineer Waterways Experiment Station Vicksburg MS Johnson B and M B Boyd 1975 Mixing zone estimate for interior guidance Unpublished Memo Mathematical Hydraulics Division Hydraulics Laboratory U S Army Engineer Waterways Experiment Station Vicksburg MS Johnson B H D N McComas D C McVan and MJ Trawle 1994 Development and verification of numerical models for predicting the initial fate of dredged material dis
84. nto STFATE As these clouds move downward material and fluid with dissolved contaminants may be stripped away Stripped material is handled through the concept of Gaussian clouds discussed below The amount of material stripped away and stored in the Gaussian clouds is computed as a coefficient times the downward velocity of the cloud times the cloud surface area The value of the stripping coefficient is selected so that approximately 2 5 percent of the total volume of fine material is stripped away at disposal sites of 100 ft or less Based upon field data collected by Bokuniewicz et al 1978 this will result in the amount of stripped material being on the conservative side 2 2 2 Dynamic Collapse Whether by disposal from a split hull barge or scow or discharge from a multi bin hopper dredge the disposed material cloud grows during convective descent as a result of entrainment Eventually either the material reaches the bottom or the density difference between the discharged material and the ambient water column becomes small enough for a position of neutral buoyancy to be assumed In either case the vertical motion is arrested and a dynamic horizontal spreading occurs The basic shape assumed for each collapsing cloud is an oblate spheroid if collapse occurs in the water column whereas a general ellipsoid is assumed for collapse on a sloping bottom With the exception of vorticity which is assumed to have been dissipated by the strat
85. o empty all hopper bins S 60 Number of bins opening simultaneously 2 Number of discrete openings of bins 3 Vessel velocity in x dir for each set ft s 6 6 6 Vessel velocity in z dir for each set ft s 0 0 0 Bottom depression length x direction ft 0 Bottom depression length z direction ft 0 Bottom depression average depth ft 0 Predisposal draft ft 18 Postdisposal draft ft 5 COEFFICIENTS Settling coef BETA 0 0 Apparent mass coefficient CM 1 0 Drag coefficient CD 0 5 Form drag collapse cloud CDRAG 1 0 Skin friction collapse cloud CFRIC 0 01 Drag ellipse wedge CD3 0 1 Drag plate CD4 1 0 Friction between cloud and bottom FRICTN 0 01 4 3 Law horizontal diffusion coefficient ALAMDA 0 001 Unstratified vertical diffusion coefficient AKYO 0 025 Cloud ambient density gradient ratio GAMA 0 25 Turbulent thermal entrainment ALPHAO 0 235 Entrainment collapse ALPHAC 0 1 Stripping factor CSTRIP 0 003 Concluded 48 z direction Thus the disposal site Fig C 11 is 1550 ft wide and 4650 ft long constant water depth is entered as 40 ft and the bottom roughness is input as the mid range value of 0 005 A flat bottom is assumed so a slope of zero is entered for the x and z directions Once the data entry screen is complete the PAGE DOWN key is pressed to move to the next screen 0 ft 1550 ft Grid Pt 1 Grid Pt 32 Grid Pt 1 1050 ft 750 ft Boundary 0 4 Grid 3000 ft Boundary Water Current
86. of milligrams per liter of dissolved constituent for Tier II evaluations or in percent of initial concentration of suspended plus dissolved constituents in the dredged material for Tier evaluations maximum concentration within the grid and the maximum concentration at or outside the boundary of the disposal site are tabulated for specified time intervals Graphics showing the maximum concentrations inside the disposal site boundary and anywhere on the grid as a function of time can also be generated Similarly contour plots of concentration can be generated at the requested water depths and at the selected print times C2 6 General Instructions for Running the Model C2 6 1 Target Hardware Environment The system is designed for the 80386 based processor class of personal computers using DOS This does not constitute official endorsement or approval of these commercial products In general the system requires a math coprocessor 640 KB of RAM and a hard disk The STFATE executable model requires about 565 KB of free RAM to run therefore it may be necessary to unload network and TSR software prior to execution The model is written primarily in Fortran 77 but some of the higher level operations and file management operations are written in BASIC and some of the screen control operations in the Fortran 77 programs are performed using an Assembly language utility program C 22 C2 6 2 Installation and Starting An executable version
87. of averaged velocity ft 40 Vertically averaged x dir velocity ft s 0 5 Vertically averaged z dir velocity ft s 0 INPUT EXECUTION amp OUTPUT KEYS Process to simulate Disp from Multiple bin Hopper Dredge Duration of simulation S 3600 Time step for diffusion f V S 300 Convective descent output No Collapse phase output option No Number of print times for diffusion Quarterly Upper left corner mixing zone ft 1000 450 Lower right corner mixing zone ft 3000 1050 Toxicity standard for dilution 0 4 Number of depths for output 2 Depths of transport diffusion output ft 20 39 MATERIAL DESCRIPTION Number of solids fraction 3 Solid fraction descriptions sand silt clay Solid fraction specific gravity 2 7 2 65 2 65 Solid fraction volume concentration yd yd 0 1 0 07 0 04 Solid fraction fall velocity ft s 0 1 0 01 0 002 Continued 47 Table C 4 continued STFATE Input Variables for Section 404 b 1 Regulatory Analysis of Navigable Waters Using a Multiple bin Hopper Dredge Disposal Solid fraction depositional void ratio 0 6 3 0 5 0 Solid fraction critical shear stresslb ft 0 025 0 01 0 002 Cohesive Y N N N Y Stripped during descent Y N N Y Y redge site water density g cc 1 0 INPUT PARAMETER UNITS INPUT VALUE DISPOSAL OPERATION Disposal point top of grid ft 1300 Disposal point left edge of grid ft 750 Length of vessel bin ft 60 Width of vessel bin ft 20 Distance between bins ft 5 Time required t
88. onal Celsius Optional 3 yd ft sec ft sec 20 Table C 2 STFATE Model Input Parameters continued Disposal Operation Parameter Types Units Option Disposal Operation Data Location of disposal point from top of grid H B ft Location of disposal point from left edge of grid H B ft Length of disposal vessel bin H B ft Width of disposal vessel bin H B ft Distance between bins H ft Pre disposal draft of Hopper H ft Post disposal draft of Hopper H ft Time required to empty all Hopper bins H sec Number of Hopper bins opening simultaneously H Number of discrete openings of sets of Hopper bins H Vessel velocity in x direction during each opening of a set of Hopper bins H ft sec Vessel velocity in z direction during each opening of a set of Hopper bins H ft sec Bottom depression length in x direction H B ft Optional Bottom depression length in z direction H B ft Optional Bottom depression average depth H B ft Optional Pre disposal draft of disposal vessel B ft Post disposal draft of disposal vessel B ft Time needed to empty disposal vessel B sec Coefficients Settling coefficient H B Apparent mass coefficient H B Drag coefficient H B Form drag for collapsing cloud H B Skin friction for collapsing cloud H B Drag for an ellipsoidal wedge H B Drag for a plate H B Friction between cloud and bottom H B 4 3 Law horizontal diffusion dissipation factor H B Unstratified water vertical diffusion coefficient H
89. oncluded C 42 the bottom before 900 s so there is no history for those sediment fractions Concentrations for clay are shown to decrease with time for both requested depths and the quarterly time entered in the input data The lead concentrations are shown for every time step for the two depths of 15 and 39 ft as well as depths 0 10 20 30 and 40 ft The model evaluates concentrations at five additional depths based on the location of clouds to better estimate the peak concentration of contaminant in the water column The last section of Figure C 7 shows the snapshot mixing zone at a instant in time and accumulated mixing zone from the beginning of simulation The snapshot columns show the area that exceeds the water quality standard at the time of the results For example at 300s a region 570 ft long 171 ft wide and 97 500 ft in area has a lead concentration that exceeds the water quality standard Areas were in violation up to and including 2400 seconds The accumulated columns show the area that exceeds or previously exceeded the standard at the time of the results appropriate required mixing zone has an area of 277 500 2 a length of 1395 ft and a width of 199 ft C2 8 1 2 3 Plots of Concentration Following Barge Disposal From the STFATE Activity Selection Menu F4 Generate Graphics is selected to receive the STFATE Graphics File Selection Menu which has several options First the name of the data file used during execu
90. opper with the dredged material solids the example the density is entered directly YES to first question and the value of 1 000 g cc is accepted If the density is different it can be entered in the highlighted box If salinity and temperature data are only available then NO 15 selected and another screen will appear to allow for the input of that data At this point PAGE DOWN is selected and the STFATE Input Selection Menu returns C2 8 2 1 5 Operation Data To describe the disposal operation F5 Disposal Operation Data is selected and the first data entry screen is used to enter data concerning location of disposal point length and width of disposal vessel hopper bin distance between bins pre and post disposal hopper draft total time needed to empty all bins and the number of bins that are opened simultaneously A schematic of the hopper dredge bin layout is illustrated in Figure C 13 actual data are entered into the respective highlighted boxes and the input data values are given in Table C 4 For this example the disposal point is 1000 ft from the top edge of grid and 750 ft from left edge of grid Fig C 11 The length and width of each is 60 and 20 ft respectively and the distance between the edge of bins is 5 ft The pre and post disposal drafts are 18 and 5 ft respectively and it takes 60 s to empty all bins Press PAGE DOWN to get next screen which requests information concerning the number of discrete openi
91. other difference in the menu is that it has an option to view the output on the monitor using the LIST COM utility program Instructions on using the LIST program are provided on the menu bar and on line by pressing the key The output is an ASCII text file having 132 characters per line and should be printed using compressed print or wide paper The program will automatically use compressed print on some printers mainly Epson and IBM printers It may be necessary to turn on compressed printing on your printer prior to printing the output or to print the output outside the STFATE program using the DOS print command or a word processor The output contains an interpretive listing of the input data computational indicators convective descent results collapse results information on cloud generation for transport diffusion simulation accumulation and thickness of deposited materials spatial distribution of concentrations of materials in the water column and water quality comparisons with standards for determining water quality violations or mixing zone requirements 29 m Generate Graphics Selecting F4 from the Activity Selection Menu brings up the Graphics File Selection Menu which is similar to the other file selection menus Unlike the other file selection procedures there are three graphics files not one as for input execution and output three files have the same name as the execution file used to generate the output and graphic
92. owing parallel to the bank of the receiving water f The major cause of dispersion in the receiving water body is the turbulence and shear flow associated with the horizontal water flow g The effluent plume is vertically well mixed so that contaminant concentrations do not vary significantly with depth h The width of the effluent plume is small enough that its lateral dispersion is not restricted by the opposite bank of the receiving water body Step 2 Identify critical contaminant It is necessary to calculate the dilution required within the mixing zone in order to reach applicable water quality standards for all contaminants of concern This requires an estimate of the effluent concentrations of regulated contaminants The contaminant that requires the greatest amount of dilution should be calculated as described in Section 5 3 The maximum boundary of the mixing zone will be defined as the isopleth line of constant concentration where the concentration of the most critical contaminant is reduced to the concentration specified by the appropriate water quality standard It should be noted that if background concentrations exceed the water quality standard the concept of a mixing zone is inapplicable Also this approach for calculating required dilution is not applicable to turbidity an optical property of water which is reduced in an nonlinear fashion by dilution A correlation curve for TSS versus turbidity should be used to
93. posed in open water Report 1 Physical model tests of dredged material disposal from a split hull barge and a multiple bin vessel Draft Technical Report U S Army Engineer Waterways Experiment Station Vicksburg MS King I P 1992 Finite Element Model for Stratified Flow RMA10 User s Guide Version 4 3 Report prepared by Resource Management Associates for U S Army Engineer Waterways Experiment Station Vicksburg MS Koh R C Y and Y C Chang 1973 Mathematical model for barged ocean disposal of waste Environmental Protection Technology Series EPA 660 2 73 029 U S Army Engineer Waterways Experiment Station Vicksburg MS Kraus 1991 Mobile Alabama field data collection project 18 August 2 September 1989 Report 1 dredged material plume survey data report Technical Report DRP 91 3 U S Army Engineer Waterways Experiment Station Vicksburg MS 80 Lin H J Jones L and Richards D 1991 Microcomputer Based System for Two Dimensional Flow Modeling Proceedings of the 1991 National Conference on Hydraulic Engineering ASCE Nashville TN MacIntyre D F 1987 Interim procedures for estimating mixing zones for effluent from dredged material disposal sites Technical Note EEDP 04 5 US Army Engineer Waterways Experiment Station Vicksburg MS Motz L H and B A Benedict 1972 Surface jet model for heated discharges J Hydraul Div Am Soc Civil Engineers 98 181 199 Prakash
94. ption of Barge Disposal Example Barge Disposal Water Column Concentrations and Area Distribution os a see LM RE n bei ede Barge Disposal Water Column Concentrations Plots of Concentration Following Barge Disposal Multiple bin Hopper Dredge Example Entering STFATE and the Input Data File Selection Menu Site Description Data Velocity Data for Hopper Disposal Example Input Execution and Output Keys Material Description Operation Data Coefficients V sins s puk su RWV WE Saving Input Data Menu Description of Example Hopper Disposal Output Hopper Disposal Water Column Concentrations and Area Distribution 2 m OR ae a ee OR eee xen Hopper Water Column Concentrations Hopper Maximum Concentration and Contour Graphs CORNELL MIXING ZONE EXPERT SYSTEM CORMIX MACINTYRE ANALYTICAL METHOD FOR CDF DISCHARGE IN RIVERINE CONDITIONS Introduction s ee eee Ree Data Requirements Calculation Procedure
95. r is entered Press ENTER The Disposal Operation Selection Menu appears and Disposal from a Multiple Bin Hopper Dredge is selected F2 key which brings up the STFATE Input Selection Menu Entering of the input data given in Table C 4 now begins C2 8 2 1 1 Site Description Data From the STFATE Input Selection Menu F1 Site Description is selected by pressing key or by using arrow keys to highlight selection and pressing ENTER the first data entry screen the number of grid points is selected as 32 in both the x direction top to bottom and z direction left to right The spacing is picked as 50 ft in the z direction and 150 ft in the x direction These spacings are selected because the water velocity described later is 0 5 ft s in the x direction and 0 0 ft s in the 46 Table C 4 STFATE Input Variables for Section 404 b 1 Regulatory Analysis of Navigable Waters Using a Multiple bin Hopper Dredge Disposal INPUT PARAMETER UNITS INPUT VALUE SITE DESCRIPTION Number of grid points L R z dir 32 Number of grid points T B x dir 32 Grid spacing L R f V ft 50 Grid spacing T B f V ft 200 Constant water depth ft 40 Bottom roughness ft 0 005 Bottom slope x dir de 0 Bottom slope z dir de 0 Number of points for density profile 2 Density at point one surface cc 1 0000 Density at point two bottom cc 1 0002 VELOCITY Type of velocity profile pt depth ave logarithmic Water depth
96. r edit input data file F2 Execute STFATE F3 Print or view output Generate graphics F5 Perform hardware configuration for graphics Esc Quit Plotter Select Manufacturer Paper size Port Baud Video Select Graphic Card Display F1 STFATE Activity Selection Menu F5 ADDAMS HARDWARE CONFIGURATION ter Select Manufacturer Model Resolution Figure C 3 Menu Tree for STFATE Model C 23 STFATE Evaluation Selection Menu F1 General Open Water Disposal Analysis F2 Section 103 Regulatory Analysis for Ocean Waters F3 Section 404 b 1 Reg Analysis for Navigable Waters F4 Determine Contaminant of Concern Based on Dilution Needs Esc Return to STFATE Activity Selection Menu F3 Figure C 4 STFATE Execution Data File Selection Menu F1 Enter name of data file to be used during execution F2 Enter DOS path to data file storage location Optional Display directory of execution data files F4 Execute STFATE with selected file Esc Return to STFATE Activity Selection Menu STFATE Output Data File Selection Menu F1 Enter name of data file used during execution F2 Enter DOS path to data file storage location Optional Display directory of output data files F4 Print selected output file F5 View selected output file Esc Return to STFATE Activity Selection Menu STFATE Graphics File S
97. r near the mixing zone may not always travel parallel to the bank Therefore simple mixing zone equations may not be applicable to the wide open low velocity sections of estuaries Also mixing zone equations are not theoretically applicable as the mean velocity tends to zero This is because the equations are dependent upon the process of advection which does not exist in the absence of a flow velocity and also because the primary source of dispersion is assumed to be the turbulence caused by the horizontal movement of water However in a real water body as the velocity tends to zero the primary sources of turbulence and dispersion are the wind and waves The rate of change of water velocity due to tidal effects can also cause problems The time taken for material to travel the length of the mixing zone should be an order of magnitude smaller than the time taken for a 10 percent change in the mean water velocity It may be possible to satisfy this condition 8 in a river but it will probably not be possible to do so in most estuaries during a significant portion of the tidal cycle Another potential difficulty in estuaries is the phenomenon of stratification Estuaries with low water velocities sometimes have a layer of relatively fresh water near the surface with a much more saline denser layer of water near the bottom and with quite a distinct interface between the two layers The abrupt change of density at the interface tends
98. ration of hopper dredges result in a mixture of water and solids stored in the hopper for transport to the disposal site At the disposal site hopper doors in the bottom of the ship s hull are opened and the entire hopper contents are emptied in a matter of minutes the dredge then returns to the dredging site to reload This procedure produces a series of discrete discharges at intervals of perhaps one to several hours Upon release from the hopper dredge at the disposal site the dredged material falls through the water column as a well defined jet of high density fluid which may contain blocks of solid material Ambient water is entrained during descent After it hits bottom 5 most of the dredged material comes to rest Some material enters the horizontally spreading bottom surge formed by the impact and is carried away from the impact point until the turbulence of the surge is sufficiently reduced to permit its deposition C1 4 3 Pipeline Dredge Discharge Pipeline dredges are commonly used for open water disposal adjacent to channels Material from this dredging operation consists of a slurry with solids concentration ranging from a few grams per liter to several hundred grams per liter Depending on material characteristics the slurry may contain clay balls gravel or coarse sand material This coarse material quickly settles to the bottom The mixture of dredging site water and finer particles has a higher density than the disposal
99. rid and 750 ft from left edge of grid The disposal began at an x and z distance of 1000 ft grid point 8 and 750 ft grid point 16 Both the hopper dredge and water velocity were in the positive x direction so it is reasonable to find the maximum concentration down grid from the disposal point Since the hopper and the water current are moving in the positive x direction it is expected that the distance in the x direction affected by the discharge should be longer than that in the z direction The display of the area with concentrations greater than 10 vol vol in Figure C 14 appears to be wider than it is long but that is because of the difference in grid spacing between the x and z direction It is actually 800 ft wide z direction and 1500 ft long x direction C2 8 2 2 2 Hopper Water Column Concentrations The water column concentrations over the duration of the simulation are tabulated in Figure C 14 This shows the clay and percent fluid values versus time sand settled to the bottom before 900 S so there is no history for this sediment fraction Maximum concentrations for silt and clay on the entire grid are shown to decrease with time for both requested depths and the quarterly time entered in the input data while outside the mixing zone the concentrations increased as the plume moved out from the mixing zone The fluid volume ratio is shown for every time step and at the two depths of 20 and 39 ft as well as the model selected d
100. s files but have different extensions graphics file selection procedure uses the graphics file with an extension of DUT for its directory listing and file searching Selecting F4 Generate Graphics with Selected File brings up the Graphics Generation Menu from which there are three options for plotting the data one for each of three types of graphics files The three options are F1 Maximum Concentrations Versus Time using the file with a DUP extension F2 Concentration Contours in Horizontal Plane using the file with a DUC extension and F3 Deposition Thickness at End of Simulation using the file with a DUT extension The plots can be viewed on the monitor or sent to a printer or plotter as desired However before plots can be generated the software must be configured for the hardware present n Perform Hardware Configuration for Graphics Select F5 from the Activity Selection Menu to choose the proper printer plotter and video information for the computer system being used o Endin To exit the program press Esc repeatedly until you obtain a DOS prompt During execution of a particular application s program the user has to wait until the sometimes lengthy computations are computed program can also be terminated by a Control Break which will stop the execution after the next screen update and provide partial output Alternatively the program can be stopped by turning off or rebooting the computer but loss of
101. s read can be used but the input and execution data files will be overwritten If the input data are complete an execution data file will also be saved After the files are saved the program returns control to the Input Selection Menu At this point data entry is complete and the user should return to the Activity Selection Menu by hitting the Esc key Execute Selecting F2 from the Activity Selection Menu see step b initiates execution by bringing up the Execution Data File Selection Menu After selecting the execution data file same procedure as the other file selection menus pressing F4 begins the simulation This option uses the execution data file to generate an output file and three graphics files of the same name as the execution data file selected but with an extension of DUO DUP DUC and DUT respectively instead of DUE The execution may take a few minutes or several hours depending on the simulation selected and the computer hardware used but typically 30 minutes is sufficient After termination of the simulation the program returns to the Activity Selection Menu Print or View Output Select F3 from the Activity Selection Menu to print or view text output A STFATE Output Data File Selection Menu will be displayed that is similar to the other file selection menus The output files have the same name as the execution data files used to generate them except that they have a DUO extension instead of a DUE extension The
102. selecting the depth desired 20 39 or peak in this example Default contours are selected by answering YES or user specified contours are selected by answering NO Figure C 16 shows one fluid percent contour at 20 ft for 3600 s after initiation of disposal The contour value was specified for only one contour and the toxicity value 0 496 was entered Thus Figure C 16 shows the standard was exceeded just outside the predefined mixing zone at that time Figure C 17 shows the required mixing zone boundary up to 3600 s after disposal as outlined by the 0 4 contour Since this contour falls outside the specified mixing the figure shows a violation of the standard The highlighted box with Mixing is selected from the screen appearing after pressing the F2 option on the STFATE Graphics Generation Menu to obtain this result The ESC key is now pressed repeatedly to return to the STFATE Activity Selection Menu HOPPER DISCHARGE WITH SPECIFIED MIXING ZONE TIER 111 FLUID a PERCENT 28 08 FT 3688 SEC D I i CONTOUR URLUES ME 1 4 888E 01 P 0 N 3608 4800 1608 Z DIRECTION Figure 16 Fluid Ratio Contours for 20 ft Depth at 3600 sec for the Hopper Dredge Disposal Example 59 HOPPER DISCHARGE WITH SPECIFIED MIXING ZONE TIER 111 MIXING B PERCENT PE K FT 36BB SEC X 1288 D I R CONTOUR VALUES 2488 1 x 4 BBBE O1 T I 0 N 3688 4800 8 1688 Z DIRECTION Fi
103. site water and therefore can descend to the bottom forming a fluid mud layer Continuing the discharge may cause the fluid mud layer to spread There will be a vertical gradient of fine suspended solids forming a turbidity layer above the fluid mud layer created by the discharge momentum and resulting turbulence and entrainment of disposal site water into the discharge plume The suspended solids concentration of the fluid mud layer is typically 10 g L or greater while the overlying turbidity layer is defined as less than 10 g L Characteristics of the plume are determined by discharge rate characteristics of the slurry both water and solids water depth currents meteorological conditions salinity of receiving water and discharge configuration C1 4 4 Confined Disposal Facility CDF Effluent Discharge Dredged material hydraulically placed in a confined disposal area settles resulting in a thickened de posit of material overlaid by a clarified supernatant The supernatant waters are discharged from the site as effluent during active dredging operations effluent may contain both dissolved contaminants and suspended colloidal particles with associated adsorbed or held by ion exchange contaminants Supernatant waters from confined disposal sites are discharged after a retention time of up to several days Furthermore actual withdrawal of the supernatant is governed by the hydraulic characteristics of the ponded area and the discharge w
104. so NO is selected Also particular 50 times for printing time diffusion results are not of importance since summary concentration data are provided for all time steps so NO is chosen which causes output to be produced quarterly 900 1800 2700 and 3600 s Again PAGE DOWN is pressed and the STFATE Input Selection Menu 15 returned C2 8 2 1 4 Material Description Data The material description data are entered after choosing the F4 Material Description Data from the STFATE Input Selection Menu next data entry screen appears and requests information on the total volume of dredged material in the hopper dredge total of all bins and the number of solids fractions in the material For this hopper disposal example the total volume is 3000 yd and the number of solid fractions is 3 The next screen is used to enter the physical characteristics of the solids fractions which are entered in the highlighted boxes on the screen Typical values and their ranges are shown at the top of the screen and the input values are shown at the bottom of the data entry screen and are tabulated in Table C 4 Press PAGE DOWN to get the next screen which asks if the adjustment of the entrainment and drag coefficients based on the moisture content are desired Typically this is not necessary and NO is selected as is done in this example The final screen for material description requests input on the density of the dredging site water which is in the h
105. step is to save the input data file for use in the execution of STFATE On the STFATE Input 52 Selection Menu press the F7 key or highlight F7 Saving Input Data Menu and press ENTER The Saving Input Data Menu appears and requests input as to whether a new file name is desired or the active data file should be used for storing the data The file name entered at the beginning of the input process appears as the active data file Sometimes a file is being edited but the original data file needs to be kept unchanged At this point a new file name can be selected using option Fl Enter name of file to be saved and then option F4 Save data in or to the active data file is chosen to save the data For the example the active data file HOPPER is selected If the active data file exists the program indicates so and requests permission to overwrite the file In this example Y is entered and the next screen requests a descriptive title for the file title Hopper Discharge with specified mixing zone Tier is entered Next the STFATE Input Selection Menu reappears and all of the selections show an asterisk indicating each selection has been completed complete the process ESC is pressed and the STFATE Activity Menu appears Now the input file is complete and saved and the STFATE model can be executed by selecting F2 Execute STFATE which then requests the input data file to be entered HOPPER is entered to obtain resu
106. t been developed and verified for national application for the indicated discharges However the fundamental far field processes contained in TABS are applicable for the indicated discharges and this model can be adapted for use on a regional basis Note that the TABS model computes far field effects only Some independent near field analysis is usually required 10 C2 0 SHORT TERM FATE MODEL FOR OPEN WATER BARGE AND HOPPER DISCHARGES STFATE C2 1 Introduction The model described in this section is the STFATE Short Term FATE of dredged material disposal in open water model Johnson et al 1994 developed from the DIFID Disposal From an Instantaneous Discharge model originally prepared by Koh and Chang 1973 This model is used for discrete discharges from barges and hoppers STFATE is a module of the Automated Dredging and Disposal Alternatives Management System ADDAMS Schroeder and Palermo 1990 and can be run on DOS based personal computers PC having 80386 or higher processors with math coprocessors ADDAMS is an interactive computer based design and analysis system in the field of dredged material management The general goal of ADDAMS is to provide state of the art computer based tools that will increase the accuracy reliability and cost effectiveness of dredged material management activities in a timely manner An executable version of the STFATE model for use on IBM compatible microcomputers can be downloaded from the
107. ta entry on this screen is complete so the PAGE DOWN is pressed next screen requests information describing the water density profile at the site First the number of points required to describe the density profile is entered as 2 This is the minimum number because the surface zero depth and the bottom 40 ft must be entered Additional depths may be needed to describe more complicated profiles with the maximum number of depths being 5 Next the method of entering density data is determined by selecting YES for direct entry of depth and density or for entering depth salinity and temperature from which density is automatically computed For this example YES is selected and highlighted boxes are presented for entering depth ft and density g cm of 0 0 1 0000 and 40 0 1 0002 respectively The data entry is now complete and pressing PAGE DOWN results in the return of the STFATE Input Selection Menu C2 8 1 1 2 Velocity Data The selection of F2 Velocity Data from the STFATE Input Selection Menu brings the Velocity Profile Selection Menu up on the monitor For this example a 2 point velocity profile Fig C 6 for a constant depth is selected by pressing the F2 key or highlighting the selection using arrow keys and pressing PAGE DOWN or ENTER velocity profile data entry screen appears and the velocity and depth data are entered by typing the data in the highlighted box and then pressing ENTER A x direction
108. ted dredged material concentrations at the boundary of the mixing zone are compared to the allowable concentrations as determined by bioassay tests A description follows for entering the required example data and the use of the STFATE module C2 8 2 1 Entering STFATE and the Input Data File Selection Menu Many of the steps and procedures for entering the STFATE model for application to a multiple bin hopper disposal operation are the same as that previously described for the barge disposal Section 2 8 1 2 Therefore some repetition is contained in this section and a complete description is given for the purpose of clarity The STFATE is executed from the DOS prompt and the STFATE Activity Selection Menu is reached as described previously To proceed the Build or edit input data file option is selected This results in the STFATE Short Term Fate of a Disposal in Open Water Evaluation Selection Menu being presented For this example the option F3 for Section 404 b 1 Reg Analysis for Navigable Waters is selected As a result the STFATE Input Data File Selection Menu appears and key F1 is pressed to enter the name of the input data file to be built or edited In this example HOPPER is typed in the highlighted box and then the ENTER key is pressed Option F4 is then selected to read the input data file if it exists or to initialize it if a new file descriptive title Example hopper dredge disposal with specified mixing zone Tie
109. the cursor within a selected cell to edit the cell s contents The Backspace key is used to clear a single character The spacebar will insert a space in alphanumeric cells PgDn key advances the cursor to the next data entry screen and the PgUp key returns control to the previous data entry screen The Esc key returns control to exit to the previous menu without loss of data The Home key permits the user to exit from the current data entry screen to the Main Menu for the application without loss of data Results from computations are generally displayed in tabular format on the screen and or written to print files or devices C2 7 Steps in Using the Model The menu driven environment for applying the model is illustrated in Figures C 3 and C 4 The general steps and menus used in applying the model for a disposal operation are as follows 1 2 3 4 5 6 7 8 9 Esc SETTLE Confined Disposal Facilities CDFs Design DYECON Hydraulic Retention and Efficiency of CDFs PCDDF Consolidation and Desiccation of Dredged Fill STFATE Short Term Fate of Disposal in Open Water EFQUAL Modified Elutriate Test Analysis WET Wetlands Evaluation Technique List data file names for all applications ADDAMS Application Selection Menu D2M2 Dredged Material Disposal Management Perform hardware configuration for graphics End current ADDAMS session Prin F1 Build o
110. tion is entered after selecting Fl Enter name of data file used during execution Next the F4 Generate graphics with selected file is pressed to receive the STFATE Graphics Generation Menu The first option is to select Fl Maximum concentrations versus time which brings up a screen with selections for how the graph is to be displayed screen printer plotter which solids fraction or contaminant clumps sand clay or lead in this example is desired and what depth 15 39 or peak are desired Peak means the water column depths at which the maximum concentrations occur The maximum concentration versus time for lead in this barge disposal example Fig C 8 shows the maximum 0 039 mg L occurring 5 min after disposal and rapidly dropping to below the mixing zone standard 0 0032 mg L at 41 min It then stays under the standard for the remainder of the simulation Referring back to the middle sections of Figure C 7 it can be determined that the depth where the peak occurred is 20 ft Selecting the option F2 Concentration contours in horizontal plane displays a screen which provides the ability to graphically display the concentration contours of the contaminant or the solids fraction It also provides capability for graphically displaying the predicted mixing zone required As before the graphs can be output to the screen plotter or printer Concentration contours are obtained by selecting the solid fraction or contaminant clumps sand
111. to inhibit vertical mixing through the entire depth of the water column C1 5 3 Recommended Models and Techniques Several models and approaches for evaluation of initial mixing are provided in this appendix Table C 1 provides a summary of the characteristics of the various types of dredged material discharges hydrodynamic environments and the models recommended for use in evaluation of initial mixing for those conditions Descriptions of each of the models and details on applying the models are provided in the following sections of this appendix 9 Table C 1 Summary of Discharge Types Hydrodynamic Conditions and Applicable Models and Methods for Evaluation of Initial Mixing Type of Characteristics Near Field Applicable Model Section Discharge of Discharge Effects Model or Hydrodynamics Discrete BARGE Discrete Strong STEATE STFATE Steady Non uniform HOPPER Semi Discrete Moderate STFATE Steady Non uniform PIPELINE Continuous Moderate Steady Uniform Unsteady Non uniform Continuous MacIntyre Steady Uniform EFFLUENT CORMIX Steady Uniform TABS Unsteady Non uniform Dilution Steady Volume Uniform Method 1 CD CORMIX has not been developed and verified for national application However the fundamental processes contained in CD CORMIX are applicable for continuous pipeline discharges and this model is currently under investigation for future use 2 TABS has no
112. tration down grid from the disposal point The lead concentration area at 15 ft is evaluated by determining the number of grid rectangles which have a value representing lead concentration and multiplying it by the area of the grid rectangle 50 x 1500 7500 ft total of 129 grid points have a lead concentration above background of at least 10 mg L an area of 9 675 x 10 2 Since the barge and the water current are moving in the positive x direction it is expected that the distance in the x direction should be longer than that in the z direction The display of this area in Figure C 7 appears to be wider than it is long but that is because of the grid spacing It is actually 1000 ft wide and 1200 ft long x direction C2 8 1 2 2 Barge Disposal Water Column Concentrations The water column concentrations over the duration of the simulation are tabulated in the middle sections of Figure C 7 This shows the clay and lead concentrations The clumps and sand settled to 39 CONCENTRATIONS ABOVE BACKGROUND OF LEAD MG L IN THE CLOUD 3600 00 SECONDS AFTER DUMP 15 00 FT BELOW THE WATER SURFACE MULTIPLY DISPLAYED VALUES BY 0 1000 02 LEGEND 01 LT 0001 O 111 000001 MN 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 2 OO00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 30000 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
113. ty standard The key parameters derived from the model are the maximum dissolved concentration of the contaminant at the boundary of the mixing zone This concentration is compared to the applicable water quality standard to determine if the discharge complies with the Guidelines C1 3 3 Evaluation of Concentrations of Suspended Plus Dissolved Constituents by Comparison with Toxicity Test Results If additional water column testing is necessary the potential for water column impact may be evaluated under Tier III by comparison of predicted concentrations of the suspended plus dissolved constituents of the dredged material with toxicity test results considering the effects of mixing For this case the dilution of the dredged material elutriate expressed as a percent of the initial volume of disposed fluid in a given volume of water column is calculated The key parameters derived from the evaluation are the maximum concentration of dredged material elutriate in the water column at the CA boundary of the mixing zone These concentrations are compared to 0 01 of the LC or EC as determined by toxicity tests to determine if the discharge complies with the Guidelines 4 Physical Characteristics of Dredged Material Discharges Knowledge of the physical characteristics of dredged material discharges is necessary for proper selection of a technique or model for evaluation of initial mixing Dredged material can be placed in open water sites

evaluation of dredged material proposed for discharge in waters of

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