Sprinkling and Well Infiltration in Managed Aquifer Recharge for Drinking Water Quality Improvement in Finland: Fid-Bau Portal

Sprinkling and Well Infiltration in Managed Aquifer Recharge for Drinking Water Quality Improvement in Finland

Jokela, Petri / Kallio, Esa

There are 26 managed aquifer recharge (MAR) plants in Finland. The main objective of MAR in Finland is the removal of natural organic matter from surface waters. A typical Finnish MAR plant consists of infiltration of lake water in an esker or other glaciofluvial sand and gravel formation and withdrawal of water from wells downstream. Basin infiltration is used most often. Some MAR plants use sprinkling infiltration and well infiltration. Sprinkling and well infiltration can be attractive for areas not suitable for the construction of basins, e.g., eskers with slopes and forest areas having recreational values with restrictions of tree cutting. Tavase Ltd. aims to construct a MAR plant (capacity $70,000 m^{3} / d$ ) in the neighborhood of the city of Tampere, Finland to provide potable water. Extensive on-site tests were conducted. The objective of this paper was to study the applicability of sprinkling infiltration and well infiltration in an infiltration site planned for potable water production of $20,000 m^{3} / d$ . Groundwater was pumped from two wells 1.6 km upstream to infiltration using a temporary, aboveground pipeline. Infiltrated water flowed underground back to the wells for recirculation. The tests lasted for 308 days and the maximum infiltration rate was $7,000 m^{3} / d$ . Two separate sprinkling rakes were built with altogether more than 100 valves to ensure an even distribution of water. Three infiltration wells (diameter 400 mm, depths 35–50 m) were constructed. Sprinkling infiltration worked well with all hydraulic loadings [ $0.03 - 0.17 m^{3} / (m^{2} h)$ ]. The design loading [ $0.07 m^{3} / (m^{2} h)$ ] could easily be doubled. Well infiltration worked well in all wells. Infiltration rate of $7,000 m^{3} / d$ could be achieved in each well. Both sprinkling and well infiltration were found suitable for MAR.