A new approach to the definition of design criteria for radial collector wells in anoxic settings

Milan Dimkic,Milenko Pusic

doi:10.2298/gabp1879031d

Abstract

The outcomes of a study on groundwater flow from a river to a radial collector well are presented in the paper. The considered well, RB-16, is part of a groundwater source that provides water supply to Belgrade (Serbia). The source relies on the alluvial aquifer of the Sava River. The groundwater is mildly anoxic (Eh ~ 125 mV, Fe2+ = 0.46 mg/L, NO3 ~ 0.24 mgN/L, O2 ~ 0.1 mg/L). The paper is specific in the sense that it presents a novel approach to the definition of water well susceptibility to iron incrustation in an anoxic alluvial setting. Maximum permissible screen entrance velocities, as well as the structural characteristics of the horizontal screens and the radial collector well itself, are determined based on correlations established between the rate of well incrustation, redox potential, iron concentration in groundwater, and screen entrance velocities. One of the criteria is that the hydraulic resistances, caused by the precipitation of iron on the horizontal screens, are being lower than specified. The correlations between maximum permissible screen entrance velocities (the velocities that still allow a lower-than-specified increase in local hydraulic resistances at the entrance to the screens) and biochemical indicators (Eh, Fe2+) were taken from previous papers by the same authors and their associates. Original software was used for hydraulic analysis of the potential capacity of the location of well RB-16. The software supports 3D analysis, including boundary conditions, and was adapted for this particular purpose.

Highlights

Urban agglomerations generally rely on the nearest water resource for their water supply
Numerous authors have studied groundwater source issues, which can be classified into several groups
Colmation is a process through which hydraulic resistances increase due to mechanical, biochemical and microbial processes (DIMKIĆ et al, 2008, 2011b, 2011c; DIMKIĆ & PUŠIĆ, 2014)

Summary

Introduction

Urban agglomerations generally rely on the nearest water resource for their water supply. The authors of this paper and their associates have correlated anoxic aquifer conditions, iron concentration in groundwater, intensity and kinetics of screen incrustation and increase in hydraulic resistances at the screens, and established functional relations between them (item d above). In the immediate vicinity of the horizontal screens of well RB-16, where the concentration of groundwater leakage through the interbed (interlayer) is the greatest, the piezometric head difference between the strata above and below is as large as ten meters. This has been established by a pair of piezometers near the said well (Fig. 2). Colmation is a process through which hydraulic resistances increase due to mechanical, biochemical and microbial processes (DIMKIĆ et al, 2008, 2011b, 2011c; DIMKIĆ & PUŠIĆ, 2014)

Methods

Findings

Discussion and conclusions