Expansive soils which create heave and shrinkage related distresses are considered to be extremely problematic globally. When these soils are used alone or in conjunction with fiber-reinforcement as hydraulic barriers in waste containment systems, their prime purpose is to impede flow. Polypropylene fiber materials are durable and sustain improvement in soil properties in the long run. In order to have intact bonding between the randomly mixed fiber and clay, an additive in the form of lime is considered. In this study, the combined effect of lime and randomly oriented polypropylene fiber inclusion on the hydraulic conductivity behavior of an expansive soil is evaluated. The dosage of lime was fixed at 6% resorting to soil-pH response. The effect of fiber type (fibercast and fibermesh), fiber dosage (0.2, 0.4, and 0.6% by weight of soil) and fiber length (6 mm and 12 mm) on the hydraulic conductivity behavior was studied. Statistical analysis was performed to correlate the hydraulic conductivity of treated expansive soil with dosage and length of randomly oriented polypropylene fibers. Two exponential best fit equations are proposed for estimating the hydraulic conductivity of treated expansive soils in terms of dosage and length of two types of polypropylene fibers. Further, reliability analysis was performed to examine the suitability of treated expansive soils for waste containment in municipal solid waste (MSW) landfills. © ASCE.