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## AMWELLS > Pit dewatering >## Dewatering by in-pit sumps |

ANSPIT calculates groundwater inflows to an open pit based on a selected conceptual scheme, the pit layout, specified time and target drawdowns. It is assumed that dewatering is achieved by in-pit sumps. For the analytical schemes of unconfined aquifer and linear source in confined aquifer, the algorithm takes into account the excavation depth of the pit.

"In-pit sumps" tab

"Target drawdown" frame |
Defines target drawdown and the time, by which the target has to be achieved (based on excavation schedule) |

"Pit radius" frame |
Determines effective radius of the pit. It can be entered manually or ANSPIT can calculate this value based on entered parameters of pit layout |

List |
You can specify effective radius (ro) using one of the following five options: 1. Manually – by entering value in the text box "Radius". 2. Width / Length > 0.5 (area-based) – radius for non-elongated layouts is calculated using area of the pit (F) by the formula: 3. Width / Length > 0.5 (perimeter-based) – radius for non-elongated layouts is calculated using perimeter of the pit contour (P) by the formula: 4. Width / Length <= 0.5 – radius for elongated layouts is calculated by the formula: d – pit length, m; b – pit width, m; η – it is defined by a polynomial: for b / d <= 0.5: 5. Complex layout – radius is calculated using the formula: n – number of polygon segments; ri – distance from pit center to vertex of polygon |

"Area" or "Perimeter" text box |
Information field. Shows the pit area (or perimeter, if the perimeter-based formula is chosen). The value is used for determination of the effective radius for non-elongated pit |

"Width / length" ratio text box |
Information field. Shows the ratio between width and length of the pit. The value is used for determination of the effective radius for elongated pit |

"Inflow to in-pit sumps" frame |
Field shows the calculated pit inflow (m3/d) for in-pit sumps with de-activated abstraction wells. CTRL-LMB – opens the conversion table for time units. If a pit inflow value is entered in this field, the pit drawdown will be calculated and displayed in the frame "Target drawdown" |

"Plot" frame |
Fields and options for two types of plots: 1) hydrograph of pit inflow; 2) pit inflow versus drawdown |

"Xmax" text box |
Maximum bound of X-axis. Minimum bound is assigned equal to the values of time or drawdown entered in frame "Target drawdown" |

"Q - lg t" option |
Plots pit inflow versus logarithmic time. Time values range from the value assigned in text box "Time" of frame "Target drawdown" to the value specified in the text box "Xmax" |

"Q - s" option |
Plots pit inflow versus drawdown. Time values range from the value assigned in text box "Drawdown" of frame "Target drawdown" to the value specified in the text box "Xmax" |

"Plot" button |
Creates plots |

"Quick estimates of pit inflow" button |
Opens the window dialog "Pit inflow". Calculates inflow rates to in-pit sumps using referenced analytical solutions |