DESIGN FOR RAINWATER HARVESTING AND UTILIZATION IN SUWON SPORTS

  DESIGN FOR RAINWATER HARVESTING AND UTILIZATION IN SUWON SPORTS COMPLEX

Kim Jeong-Han¹⁾  Kim Sun-Heack²⁾,   Won Jeong-Yeon²⁾

 1)CEO,  GeoMarine Corporation.

 2)Environmental Policy Division, City of Suwon

1. Introduction

In Korea, we have suffered from the management of rainwater harvesting due to the peculiarity of monsoon climate and local torrential rainfall, especially in summer season.  The natural disasters such as flood, drought and etc. are expected to increase at the time of rainy season caused by high density of population, increase of non-permeability areas and huge mountainous topographical characteristics.  Forming a line in the chain of policy to decrease natural disasters, it is judged at present that the existing management systems such as dam, rainwater pumping station, swale and etc. are confronted with difficulties.

To solve these problems, we would like to suggest counterproposal with our unique design for rainwater harvesting and infiltration facilities to decrease of outflow in consideration of decrease of outflow at the time of flood and leveling-up of underground water, and hope to make a counterproposal with the new paradigm for the prevention against disasters caused by the problem of global warming.

2. Design for Rainwater Storage Tank

 2.1 General Summary

   Watershed area of Suwon Sports Complex is 2.81km2 and joining type sewer     lines running east and west ( 2.0 X 2.0 X 2 lines ) are passing through         baseball ground and same sized lines are running toward west through          football ground.  The total area of sports complex of 180,000 m2 is consist of     indoor gymnasium, football ground, baseball ground, auxiliary stadium and       park.

   We had an experience in severe rain storm falling 104mm per hour in 2000,     which corresponds with 200 years frequency.  The counter flow of this rain storm from down stream of Seohocheon made housing complex submerged. 

   To solve this problem, it is judged to be more economical that we had better to adopt the system to be well function at 20 years' probability rainfall of 87mm per hour than expansion of existing sewer lines designed for 10 years'  probability rainfall of 77.1mm per hour and the required quantity of storage  tank is calculated as 14,000m3. 

 2.2  Summary of Design

   The adopted design concept of this new paradigm is to save energy by         reducing of city water to operate facilities at Sports Complex.  And this design was approached to manage efficiently rather than prompt discharge of  rainwater by using water abundantly so that we can obtain desired results of  disaster prevention and reducing of heat island phenomenon.

   The rainwater storage tank is designed as round corrugated steel sheet of       4.5m's diameter, and infiltration facilities are designed as plastic

   Among designed rainwater utilization facility of 14,000㎥ capacity, storage        tank of 14,000m3 was installed dispersedly at 3 places ( 4,000㎥ - 1, 3,000㎥     - 2 ), and designed each storage tank to be connected to infiltration facilities  of 4,00㎥.  Rainwater storage tank is designed that baffles each 1,000㎥ to be     installed so that method of collecting of rainwater can be variable according to the purpose of use, and designed to flow from sewer line to storage tank  for flood control in an emergency. Especially, when the capacity of rainwater  storage tank exceeds more than 2/3 level,  it is considered that the water  shall overflow to infiltration facility through overflow pipe installed at  appropriate position for flood control and level-up of underground water.

   In consideration of variable uses of water, it is designed to supply irrigation     water for lawn grounds of baseball and football, and for fire fighting and        cleaning. And it is designed that water can be supplied through installed        sterilization tank by means of bubbles for the uses of water park and           drinking water.

   Also it is planned to install 3 types of infiltration facilities on the sides of       parking lot for reduce of outflow at the time of rainfall, and to recover the  upper part of rainwater storage tank with lawn type infiltration block.

   For the effective management of rainwater utilization facilities, we completed     the design for the system to manage and monitor the total storage tanks by     means of rain gauge combined with IT. Combining Suwon City's web site  with monitoring system, any citizen can observe these rainwater utilization facilities, which is the first trial in the world.

3. Expected Effects

1. Regarding prevention system against disaster, it was designed to  reduce lancet leakage by 50% against flood and not to be discharged 100mm per event in sports complex, and it can be expected to reduce  outflow by application of rainwater storage and infiltration facilities.

2. Present consumption of city water can be reduced 50% per year by means of improvement of self-supply and utilization of rainwater for  sprinkler, toilet and drinking water.

3. For filling of underground water, present level of underground water can be risen by 0.5 cm every year by means of installation of infiltration facilities (4,000m3.equi), infiltration holes at parking lot (3 places) and rainwater storage.

4. We can expect to induce visitors of about 50,000 per year for their study and observation by operation of monitoring room and P.R.  exhibition hall. 

5. It can be substituted for the development of water resources (90,000 ton) by utilization of rainwater.

   *180,000 m3 (catchment area) X 1,286mm (average rainfall, 1993~2007) X 40% (utilization rate on working drawing) = 92,592m3≒ 90,000 ton

Reference Document:

Report on basic and working drawings for rainwater storage facilities for Suwon Sports Complex, 2009