The method of calculation of vertical drain performance when using siphon drains for infiltration water intake

The efficiency of the vertical air-lift drainage systems of the left bank of the Kakhovka water reservoir within the Kamenskiy Pod massif is analyzed. It is established that air-lift drainage systems are not effective because of low efficiency of air-lift systems caused by a constant decrease in production rates due to the flotation of their filters with flakes of ferric hydroxide that is formed as a result of the interaction of air pumped by compressor stations to the wells and drainage water containing colloidal hydrogen carbonate gland. It is proposed to increase the efficiency of the operation of anti-filtration structures by means of re-equipping the air-lift system from the drainage wells to the siphon system. The technique for calculating vertical drainage with a siphon drainage system of gravity groundwater is presented on the basis of hydraulic, hydrogeological and technical-economic calculations of the joint operation of all interacting structures of the anti-filtration protection system. Based on the calculation of the interacting drainage wells, an algorithm for calculating vertical drainage with a siphon tapping system has beendeveloped to determine the flow rate from each well and to reduce the static water level. The algorithm includes nine interrelated blocks and calculations using the formulas of the above methodology. It has been established that the water flow from the drainage wells with the siphoning method of water abstraction depends on the depth H, the number of interacting wells , the distance between the wells , the specific hydraulic resistance A, the radius of the water intake well r, the vacuum height Hvac., The aquifer layer filtration coefficient, a depression funnel R of a well, well production rate and many other factors, and the optimum parameters of a siphon system for withdrawing water from drainage wells aredetermined by calculations according to the proposed technique by iteration.