AWWA WQTC58907

Deeper brackish ferrous and manganous water intrusion in freshwater aquifers is a frequentproblem that can affect the quality of water resources.In San Lorenzo, a city of 30,000 inhabitants in Argentina, historical problems of water quality,provided by downtown wells, concerned water utilities from its origin in the 50s: highsulfates, chloride, sodium, ferric and manganese contents. Obstructions and occurrence ofblack water were common problems in the distribution system.Hydrogeological studies determined that brackish reduced aquifer underlies the freshwateraquifer used by the production wells. As a result of pumping, the hydraulic potentialequilibrium of the aquifer was disturbed, causing saline, manganous and ferrous water intrusion todegrade the well water.A project was initiated consisting of restoring the hydraulics equilibrium of the aquifer by anextraction of brackish water by means of "a correction well" near the production well. Thissolution was firstly studied by modeling and, after a comparative analysis with otheralternatives, implemented on site.The project has been ongoing since the beginning of 2000. At the source point and in the waternetwork total dissolved solids (TDS) diminished from 2.5 to 1.2 g/L. Fe and Mn total contentspassed from 0.9 and 0.7 mg/L respectively to <0.05 and <0.03 mg/L. A drastic reduction oftaste and color customer claims and maintenance intervention over the network wereregistered in San Lorenzo city.Regarding investments, groundwater management was 8% less expensive than the classicaltreatment solution of reverse osmosis (RO). The operation cost was estimated to be more than 50% less expensive for this case in comparison to the RO solution. Includes 4 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

11/02/2003

Number of Pages:

7

File Size:

1 file , 450 KB