A Modeling Framework for the Design of Collector Wells

Abstract

We present results of a design study performed for the Saylorville Wellfield in Iowa, which is owned and operated by the Des Moines Water Works. The purpose of this study was to estimate wellfield capacity and provide a preliminary design for two radial collector wells to be constructed in the outwash aquifer along the Des Moines River near Saylorville, Iowa. After a field investigation to characterize the aquifer, regional two-dimensional and local three-dimensional, steady-state groundwater flow modeling was performed to locate and design the wells. This modeling was the foundation for design recommendations based on the relative performance of 12 collector well designs with varying lateral numbers, elevations, screen lengths, and orientations. For each site, alternate designs were evaluated based on model estimates of the capacity, the percent of surface water captured, and the production per unit length of screen. Many of our results are consistent with current design practices based on experience and intuition, but our methods allow for a quantitative approach for comparing alternate designs. Although the results are site-specific, the framework for evaluating the hydraulic design of the Saylorville radial collector wells is broadly applicable and could be used at other riverbank filtration sites. In addition, many of the conclusions from this design study may apply at other sites where construction of radial collector wells is being considered.

Recent advances in modeling of well hydraulics

“…For the hydraulic design of collector wells, Moore et al [258] developed a model based on the analytic element method to discuss the challenges and comparisons associated with alternate designs. Similarly, Patel et al [263] also developed a model based on the analytic element method to simulate the steady-state discharge-drawdown relation for a radial collector well in an unconfined riverbed aquifer.…”

“…In addition, numerical modeling can also be used for the design of collector wells or the determination of well field capacity. Several different numerical approaches were used for the simulation of flow induced by radial collector wells in the past; for example, finite difference method [260], finite element method [261,262], analytic element method [258,262,263], and boundary element method [264].…”

“…A radial collector well generally comprises two main components: the central concrete caisson and lateral well screens or, simply named as laterals. Moore et al [258] mentioned that the laterals may be constructed in many configurations and the use of the configuration influences well performance and filtering water quality. They also provided five lateral geometric design alternatives.…”

Hydrodynamic simulation and analysis of groundwater regime as impacted by radial collector wells: A case study of Belgrade's water supply source

“…U poslednjih 15-tak godina se za simulaciju BHD u svetu uspešno primenjuju različiti višeslojeviti, trodimenzionalni numerički modeli analitičkih elemenata [10][11][12]. Ova metoda, međutim, nije našla primenu u detaljnoj analizi bunara na beogradskom izvorištu.…”

Predicting Collector Well Yields with MODFLOW

“…Their code is based on TimML Bakker 2004, a Bessel AEM code that allows for variable aquifer properties in horizontal layers. However, a major computational effort is required for the Bessel elements; for field applications, a regional 2D model is often used to derive boundary conditions for a local 3D TimML model (see Moore et al 2011). Detailed analysis of 3D flow near the collector well laterals, including pathline tracing, is supported.…”