Recently, Low Impact Development (LID) technology has been developed and used to collect, infiltrate, filter and confine runoff in order to enhance the storm water quality and to preserve the natural water cycle. In this study, two technologies were employed in order to treat runoff from an impervious surface such as a paved road and a parking lot. The infiltration trench which was constructed to manage stormwater runoff from a paved road abates and temporarily holds stormwater runoff and removes sediments and attached pollutants within the sub-surface structure prior to infiltration into the subsoils. On the other hand, the tree box filter which incorporates trees and other gardening plants to regulate and treat runoff drains the stormwater from a parking lot. The infiltration trench and tree box filter represent only 1% of the catchment area that they drain. This research was conducted to evaluate the hydrologic and water quality effects of the infiltration trench and tree box filter after LID. Storm event monitoring was conducted for the infiltration trench from May 2009 to August 2014 with a total of 38 storm events and 24 storm events in the tree box filter from July 2010 to July 2014. Hydrologic (i.e., total rainfall, antecedent dry day (ADD), runoff volume, etc.) and water quality (i.e. particulates, nutrients, organics, and heavy metals) parameters were analyzed before and after LID. The major findings of this study are as follows: The runoff before LID was discharged directly to the sewers and could lead to local flooding of transport systems and pollution to receiving waters during intense storm events. But, after LID the runoff was partially reduced for atleast 50% on the two (2) urban landuses. Furthermore, the pollutant concentration before LID was observed to be at high concentrations. However, it was reduced to an approximate of 60% after LID. With the combined processes of infiltration, filtration, retention and evapotranspiration that were provided by the infiltration trench and tree box filter, the runoff was partially reduced and a significant decrease in pollutant concentration has been observed. The results and findings of this study will help facilitate the LID for further application.

Urban stormwater runoff was considered to be more contaminated than the runoff from other land uses due to vehicle and human activities. Specifically, road runoff was commonly regarded as the primary pollutant (e.g. particulates and heavy metals) in the urban environment. Effectiveness of stormwater management strategies and treatment facilities in treating road runoff were highly based on the accuracy of the stormwater quantity and quality estimation. Although direct sampling of runoff during a storm event effectively quantifies the contaminant contributions in a specific area, it is expensive and time consuming. In order to efficiently design these treatment facilities based from the typical pollutant and hydrologic processes, the operation of modelling techniques were recommended. In this research, the physical characteristics of an existing tree box filter treating road runoff were adjusted using stormwater management model (SWMM) to determine the most suitable design configuration for better volume and pollutant reduction. The catchment area (CA), storage volume (SV) and surface area (SA) of the facility was increased or decreased by an increment of 25%. These changes were simulated by SWMM and would predict the influence of larger or smaller CA, SV or SA with respect to the facility performance. The hydrologic, hydraulic and water quality data used in the modelling were gathered from the 10 storm events monitored from July 2012 to July 2013. The total suspended solids were considered as the main target pollutants for this research however, the results will be correlated with the common heavy metal constituents present in the sampled runoff. Various design installations (e.g. series and parallel installation of tree box filter) were also modelled to accurately justify the obtained design configurations. Among the different configurations simulated, increasing the original values of the CA, SV and SA between 0.75% and twice the original value would result to better performance for the system. As for the installations being modelled, a centralized system would provide better volume and pollutant reduction than a divided system.

도로는 포장지역으로 불투수율이 높고 차량의 운행으로 인하여 비점오염물질의 축적이 큰 토지이용이다. 도로는 대부분 수계와 연관되어 강우시 처리되지 않은 비점오염물질 및 첨두유량으로 인하여 환경수리학적 문제를 야기하여 수생태계에 악영향을 미친다. 이에 미국, 유럽 및 일본을 비롯한 선진국에서는 각종 수리학적 문제를 해결하기 위하여 환경 친화적인 기술을 개발, 저영향개발 기술 (Low Impact Development) 기술을 적용함으로써 도시내 건전한 물순환 구축 및 수생태 보전을 위한 효율적인 유역관리를 하고 있다. 이러한 기술은 강우유출수의 유출을 지연시켜 개발 이전의 지역이 가지고 있던 수리학적 기능을 최대한 흉내 내는 효율적 유역관리로 도시개발사업 등에 적용되어 지고 있다. 따라서 본 연구에서는 도시지역 물순환 시스템의 왜곡 및 수생태계 복원을 위하여 저류 및 여과 기작이 적용된 도로 LID 기술을 개발하고자 수행되었으며, 현장에 적용된 1.4m×1.4m×2.0m (L×W×H) 규모의 Test-bed를 통하여 수목여과시설에 대한 평가를 실시하였다. 본 연구를 통하여 수목여과시설의 비점오염저감 능력에 대한 평가 결과, 10mm 이하의 소규모 강우에서는 대부분의 비점오염물질 항목에서 유입량 대비 70% 이상의 저감되었고, 10mm 이상의 대규모 강우의 경우 40% 이상의 저감효율을 나타내는 것으로 조사되었다. 또한 물순환 기여도 평가를 통하여 10mm 이하의 소규모 강우가 발생할 시 유입수의 73.7%가 시설 내 저류되었으며 10mm 이상의 큰 강우 발생 시에도 유입수의 30.7%가 저류되어 물순환 기여에 도움이 되는 것으로 나타났다. 따라서 본 연구의 수목여과시설이 도로에 적용시 비점오염물질의 유출 저감에 기여하여 개발과 환경이 공존될 수 있으며 도시내 물 보유를 높여 자연적인 물순환에 기여 할 수 있을 것으로 판단된다.