Analysis of Effect and Necessity of Perforated Pipes by Type of Runoff in Bio-retention

Abstract

As urbanization progresses, the impervious area has rapidly been increasing. Accordingly, the need to build eco-friendly water circulation system is demanding. In particular, in order to prevent flooding caused by the increasing impervious area and to prevent non-point pollution damage from rainfall runoff, low impact development (LID), which is based on nature solution had been developed. Bio-retention which is one of many LID technologies have been installed in several regions in Korea. That is consisting of a soil layer with plants, a sand layer, and a gravel layer, and at the same time reducing nonpoint pollutants by adding planting soil layer in the underground penetration process. The design elements and parameters of such bio-retention include the soil layer, width, depth, water quality treatment capacity, and types of vegetation. Perforated pipes have not been considered to factor the design of the system. However, the current manual provided by the Korean government agency for non-point pollution reduction facilities (Ministry of Environment, 2020) does not well describe the storage effect or pollutant reduction effect when a perforated pipe is installed, and it is not clear on what kind of basis the perforated pipe be installed, and the standards about the perforated pipes are not determined as well. Therefore, the effect of perforated pipes in the bio-retention according to the types of runoff is studied through rainfall monitoring and its analysis in the bio-retention in this study. And then comparative study with international case studies was made with these results.