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Calculations for open pits inflow are based on published analytical solutions for the following hydrogeological conceptual schemes:
•Confined aquifer;
•Unconfined aquifer;
•Confinedunconfined aquifer; and
•Leaky aquifer
Most schemes account for Ist or IInd types of boundary impacts. The aquifer can be modelled as infinite, bounded, stripped or radial (circlebounded).
The calculations are performed from the graphical window dialog "Pit Inflow". The dialog contains pit sketches in plan and profile as well as required fields for inflow calculations. The module will determine drawdown in a pit, when pit inflow is entered. When entering values in text box "Q, m^3/d" and "t, d"), inflow rate and time can be converted to other units using SHIFT (or CTRL) + MB.
To access this module, use "Hydrogeologist workbench > Pit inflow" or the button "Quick estimates of pit inflow" in the tab "InPit sumps" of the dialog window "Pit" (use button "Pit" on the dialog window AMWELLS).
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Dialog window "Pit inflow"
"Q, m^3/d" text box 
Information field showing the result of pit inflow calculations. If pit inflow is entered manually in this field, the calculations are conducted for drawdown 
"so, m" text box 
Drawdown in the pit (the same drawdown is assumed for the whole pit area) 
"ε, m/d" text box 
Recharge rate. This field is required for calculation of Radius of influence using the formula with recharge input 
"Q', m^3/d" text box 
Additional inflow. Use for circle aquifer for Neumann boundary 
"s, m" text box 
Drawdown in an observation well. This field is required for calculation of Radius of influence using the formula with drawdown in the observation well 
"k, m/d" text box 
Hydraulic conductivity 
"B, m" text box 
Leakage factor that is required for the "leaky aquifer scheme 
"H, m" text box 
Hydraulic head that is calculated in meters above the aquifer bottom. This field is required for calculations of confinedunconfined hydrodynamic conditions 
"m, m" text box 
Thickness of confined aquifer or initial saturated thickness of unconfined aquifer 
"ro, m" text box 
Effective radius of the pit. Can be entered manually or calculated (see frame "Pit radius") 
"R, m" text box 
Effective radius of the pit. Can be entered manually or calculated (see frame "Radius of influence"). This field is required for infinite aquifers. For an aquifer with circular boundary the entered value should correspond to the aquifer radius 
"r, m" text box 
Distance from the pit center to an observation well. This field is required for calculations of Radius of influence using the formula with drawdown in an observation well 
"L1, m" text box 
Distance from the pit center to the aquifer boundary (for aquifers with one boundary) or to the 1st boundary (for aquifers with two boundaries) 
"L" text box 
Width of strip aquifer 
"L2, m" text box 
Distance from the pit center to the 2nd aquifer boundary (for aquifers with two boundaries) or to the center of the aquifer (for aquifer with radial boundary) 
"Conceptual scheme" list 
Conceptual scheme for an aquifer (i.e. confined, unconfined, confinedunconfined or leaky aquifer) 
"Boundaries" list 
Hydrodynamic boundaries (infinite aquifer, stripped aquifer, square aquifer etc.) and boundary types (Neumann or Dirichlet) 
"Pit radius (ro)" frame 
Options to calculate pit radius using pit area, length and perimeter 
"Area", "Perimeter" text box 
Pit area (perimeter) that is required for calculations of Radius of influence for the nonelongated pits (ratio Width/Length > 0.5) 
"Length", "W / L" text box 
Pit length and its ratio to pit width. These fields are required for elongated pits with Width/Length ratio less than 0.5 
"Radius of influence" list 
Selects the method of calculation for Radius of influence: manually, using formula with recharge input, water level in observation well or storage properties 
"Transient conditions" frame 
This field is required when Radius of influence is changing with time and is calculated using hydraulic diffusivity (text box "a") or specific yield (text box "Sy") and time (text box "t"). Use this parameter for infinite aquifers and also for aquifers with boundaries that can not be modeled in steady state 
Button "Heterogeneous stratified aquifer" 
For unconfined aquifers. See section "Heterogeneous stratified aquifer" 
Button "Report" 
Creates report. This option is available in Russian language only 
Analytical solutions for calculations of pit inflow (Q) and pit drawdown (so) for confined, unconfined and confinedunconfined aquifers
Boundaries 
Confined aquifer 
Unconfined aquifer 
Confinedunconfined aquifer 
Unlimited aquifer (radius of influence is required) 

Radius of influence can be estimated outside of the module and entered manually. Other option is to use inbuilt formulas of the dialogue window: 1) general formula for transient groundwater flow:
2) general formula with recharge: 

Unlimited aquifer(drawdown in observation well is required ) 

One boundary of the Ist type (Dirichlet) 

One boundary of the IInd type (Neumann) 

Strip aquifer with two Dirichlet boundaries 

Strip aquifer with two Neumann boundaries 

Strip aquifer with one Neumann boundary and one Dirichlet boundary 

Square aquifer with Dirichlet boundaries 

Square aquifer with Neumann boundaries 

Square aquifer with Dirichlet and Neumann boundaries 

Aquifer with radial boundary (Dirichlet) 

Aquifer with radial boundary (Neumann) 

Analytical solutions for calculations of pit inflow (Q) and pit drawdown (so) for leaky aquifers
The pit inflow is calculated using the formula for unlimited aquifer and drawdown formulas for each type of boundary
Boundaries 
Leaky aquifer formula 
Unlimited aquifer 

One boundary of the Ist type (Dirichlet) 

One boundary of the IInd type (Neumann) 

Strip aquifer with two Dirichlet boundaries 

Strip aquifer with two Neumann boundaries 

Strip aquifer with one Neumann boundary and one Dirichlet boundary 

Square aquifer with Dirichlet boundaries 

Square aquifer with Neumann boundaries 

Square aquifer with Dirichlet boundaries 

Aquifer with radial boundary (Dirichlet) 

Aquifer with radial boundary (Neumann) 