Assessing the effectiveness of drywells as tools for stormwater management and aquifer recharge and their groundwater contamination potential

Abstract

s u m m a r y Drywells are gravity-fed, excavated pits with perforated casings used to facilitate stormwater infiltration and groundwater recharge in areas where drainage and diversion of storm flows is problematic. Historically, drywells have predominantly been used as a form of stormwater management in locations that receive high volumes of precipitation; however the use of drywells is increasingly being evaluated as a method to supplement groundwater recharge, especially in areas facing severe drought. Studies have shown that drywells can be an effective means to increase recharge to aquifers; however, the potential for groundwater contamination caused by polluted stormwater runoff bypassing transport through surface soil and near surface sediment has prevented more widespread use of drywells as a recharge mechanism. Numerous studies have shown that groundwater and drinking water contamination from drywells can be avoided if drywells are used in appropriate locations and properly maintained. The effectiveness of drywells for aquifer recharge depends on the hydrogeologic setting and land use surrounding a site, as well as influent stormwater quantity and quality. These parameters may be informed for a specific drywell site through geologic and hydrologic characterization and adequate monitoring of stormwater and groundwater quality.

Adapting aquifer storage and recovery technology to the flood-prone areas of northern Ghana for dry-season irrigation

“…these are subsurface techniques and the first of this method is infiltration of the vadose zone (i.e., unsaturated zone), which involves dug trenches (5-15 m deep) or wells in the vadose zone for vertical infiltration of water (Bouwer 1989(Bouwer , 2002Edwards et al 2016;Gale and Dillon 2005). It is usually inexpensive and suitable where there are insufficient lands or impermeable soils for the surface infiltration described earlier.…”

“…It is usually inexpensive and suitable where there are insufficient lands or impermeable soils for the surface infiltration described earlier. The direct recharge well is suitable in areas where techniques such as surface infiltration and vadoze zone infiltration are not applicable, and aquifers are often deep or unconfined (Bouwer 2002;Edwards et al 2016). The use of ASR, which is a relatively new technique, employs a combination of recharge and a pumped well (Pyne 1995;Bouwer 2002).…”

“…This study will concentrate on ASR using a borehole to infiltrate and abstract water. As an artificial recharge method, ASR can be viewed as a way of augmenting the natural movement of surface water into underground formations by some method of construction or artificially changing natural conditions (Todd 1980;Asano 1985;Bear 2012;Edwards et al 2016). ASR is a water conservation technique, and it is useful for boosting groundwater levels in semi-arid areas where rainfall variability leads to insufficient groundwater recharge (Asano 1985).…”

“…The Bhungroo is designed and sited with the aim of freeing farmlands from waterlogging; relatively flat terrains or locations of adjoining floodplains are potentially useful in this context (Naireeta Services 2015;Paul 2013). The infiltration component is designed with different materials of unique sizes to remove unwanted matter and odor (when activated, a charcoal layer is added) from the water source before transmitting it underground (Bouwer 2002;Pyne 2005;Edwards et al 2016). The Bhungroo borehole is connected with a pipe system, which may have screens at various sections, and is labelled '1' in Figure 2.…”

“…surface runoff and/or rainwater. Both the quantity and quality of water are crucial for the success of a Bhungroo scheme, in terms of sufficient capture and efficiency of water infiltration (Bouwer and Rice 2001;Bouwer 2002;Edwards et al 2016). …”