«TehnoWELL» Company, Arkhangelsk, Russia:

Davydov A. S., Chief Executive Officer, e-mail: davydov@geo29.ru

«Severalmaz» Company, Arkhangelsk, Russia:

Kostylev A. A., Head of Dewatering Area
Shkil I. E., Chief Hydrogeologist

Open pit development of Arkhangelskaya pipe of Lomonosov deposit was held in hard hydrogeological conditions. In 2012, the total capacity of dewatering system with 103 meters of open pit`s depth exceeded 3300 m<sup>3</sup> per hour.
Water drawdown is realised by the in-pit drainage and by the contour system of dewatering wells, which are equipped for the Padun waterbearing complex. The decision about the input of the drainage contour wells was made for the protection support of open pits of Arkhangelskaya and Karpinsky-1 pipes from the underground waters on the industrial stage of a deposit development. The input of the drainage contour wells is realised in two stages. On the first stage of a water drawdown, the 38 dewatering wells are constructed, when the distance between wells is 200 meters. The pumps with a 120 m<sup>3</sup> per hour productivity are put on the wells. On the second stage, the number of wells increases to 75, the distance between them decreases to 100 meters, with the pumps` productivity of 65 m³ per hour.
The diameter of well drilling is 590 millimeters, with the reckoning that the layer thickness of gravel pack is more than 150 millimeters in the 273 millimeters hole clearance of the filter coloumn. Water dump system of a drainage waters of drainage contour wells consists of the bailing collectors with 219–630 millimeters diameter, which were constructed on the surface, along with the drainage contour wells` boundary. The normally pure waters are delivered to the bad-branch duct, using the drainage contour wells.

Implementation of these conditions leads to the recovery of the geological situation near open pits, along with providing the safe conditions for further development of deposit wastes.

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