Stormwater Capture Efficiency of Dry Wells and Effects of Precipitation Conditions and Deployment Strategies

Abstract

Dry wells are increasingly used for stormwater capture and groundwater recharge in drought- and flood-prone regions like California, yet their performance and optimal deployment strategies remain poorly understood. This study developed a computational model and conducted a case study using long-term rainfall data and dry wells from the Laurel Canyon Boulevard Green Street Project in Los Angeles, CA, to evaluate the effects of precipitation conditions and deployment strategies on dry well performance. Results showed that the studied dry wells captured 28.8 ± 14.0 acre-feet of stormwater annually─sufficient to meet 10–30% of indoor residential demand within the catchment. When measured as a percentage of rainfall captured, dry well performance remained stable across years despite annual rainfall variability but was higher for long, mild storm events. The analysis also identified a maximum effective infiltration rate per system. Below this threshold, increasing the infiltration capacity of dry wells may be cost-effective, while above it, more wells are needed to improve capture. Additionally, dry wells in series at the catchment outlet maximize water capture, while distributed systems better mitigate flooding. These findings support improved dry well design and siting strategies and provide a foundation for planning under future climate conditions.