The Determination of Soil Infiltration Rate of Urban Bioretention Design Process in Chiang Mai, Thailand

Stormwater runoff is an issue that increasingly affecting urban areas because previously were permeable have been developed, and are now impermeable, comprising hard surface areas, whether concrete floors, roads, or buildings. As the size of problem area increases, amount stormwater needs to be cleared from it takes longer for cleared. The existing basic public drainage systems can no sufficiently support increasing runoff, directly commuting lifestyle. These problems led design concept bioretention, which used increase efficiency water infiltration soil since a higher rate help relieve burden on system alleviate abovementioned problems. Bioretention consists three layers: layer at bottom, transition layer, filter media top. critical objective (the top layer) greater than original soil. This research, therefore, comprises experiment in sand mixed with achieve these increased rates. Three different soil-to-sand ratios field tested within Faculty Engineering, Chiang Mai University, Mai, Thailand double-ring infiltrometer technique test rate, 1:1, 1:2, 1:4. research also applied Horton's Theory Perforation Prediction Equations; experiments demonstrated adding rate. rates 1:3 16.09, 21.53, 28.90 mm/hr., consecutively. 
 In addition, understanding relationship between ratio makes possible determine permeation as required. Furthermore, knowing useful future planning appropriate design.