Low Impact Development (LID) is a paradigm shift in how we develop land and address rainfall which falls on these developed areas. LID requires an evaluation of the natural hydrologic system on and near a site with the focus being that the post-development conditions mimic the natural hydrologic conditions. LID also focuses on small, frequent rainfall events, generally being 2.5 cm/24 hours instead of large, infrequent rainfall events as current stormwater management commonly does. However, as LID is being implemented around the world, many places are experiencing concerns with the design, installation and maintenance of LID systems. In the United States, we have experienced many failures of various types of LID systems. In some cases, the design is at fault, in others the installation was not done properly. However, the lack of any or proper maintenance of LID systems has resulted in the highest number of failures. South Korea is taking a unique approach to addressing these issues.
Land & Housing Institute (LHI) is researching various aspects of LID and how they can be applied on projects built by Land & Housing Corporation for existing and proposed cities. LHI has implemented LID concepts, such as rainwater harvesting, swales and infiltration systems for several projects, including an expansion of the city of Asan. When the completed project is turned over the city government of Asan, there has be resistance from the city to maintain the LID systems. As a result, often no or inadequate maintenance is done which adversely affects the functionality of the LID systems and basically defeats the purpose of using LID in the first place.
Dr. Choi, a Senior Research Fellow at LHI is leading an effort with other researchers at LHI are trying to address these issues this report. They have development a document entitled “A Study on Introduction Plan of Low Impact Development Techniques in Multi-Functional Administrative City
(MAC) (I)” for a project Sejong city, which will be published sometime in 2018. The plan is for this
report to be used as a template for all cities in South Korea to facilitate the implementation of LID. The report discusses the importance of the natural hydrologic conditions and why it is important to maintain these conditions for post-development conditions. The report proposes to create a template approach to apply LID concepts to new develop areas in South Korea. As LID is not a one-size fits all approach to development, the report discusses different LID approaches for different types of development, from single family residential to multifamily to commercial development. A key aspect of this approach is the inclusion of a discussion of the construction and maintenance issues associated with each type of development. Design guidelines and details are provided for the various types of LID systems to be considered for the expansion of cities. The report also provides maintenance protocols to be implemented for each type of LID system which is very important as well as education for the end user, be it homeowners or municipal government.
There are several key outcomes from this project:
• Establish design guidelines for LID systems, as well as providing detailed design drawing for these LID systems,
• Create LID checklists to ensure that each LID system is constructed in accord with the design,
• Create LID maintenance manuals for the municipalities who will ultimately responsible for these LID systems,
• Create educational and promotional material to improve the acceptance of LID systems in South Korea,
• Create cost estimations for LID systems for both design/construction as well as maintenance,
• Transference of this knowledge to other cities in South Korea and potentially in other countries to further the implementation of LID.