Evaluation of Critical Parameters to Improve Slope Drainage System

Table 3

Materials used for single- and double-pipe experiments.

Amount of pipes	Mass of soil (kg)		Mass of water (kg)		Mass of filter material (kg)
	Sand	Lateritic soil	Sand	Lateritic soil	Oil palm shell	Quarry gravel
Single	167.28	139.41	31.11	30.67	1.674	4.9192
Double	161.76	—	30.09	—	3.348	9.8384