the waste soil e g caco 3 as calcite or aragonite ca oh 2 u2014 hydrated lime cao u2014 lime and others a variation of this technique with added matrix materials e g fly ash incinerator ash cement kiln slag and ash etc can be used to fill larger void spaces of coarse ground waste materials such as gravels coarse sands waste debris etc found in abandoned mine workings c introduction or impregnation of the waste zone which is waste and admixed soil or overburden with sequential solutions that react to produce a precipitate that fills pore space e g cacl 2 solution na 2 co 3 solution caco 3 precipitate 2nacl solution loss to external soil groundwater this application of the solutions can be repeated until refusal occurs other examples of these solutions include cacl 2 na 2 so 4 caso 4 precipitate nacl solution cacl 2 na 2 hpo 4 ca 3 po 4 2 precipitate nacl solution d sequential solution gas phase impregnation of the waste zone to produce a calcium carbonate precipitate and cementing action or result as the reaction proceeds for example another embodiment of this application is the admixture of solid hydrated lime or the introduction of slaked lime into the waste zone prior to the introduction of co 2 yet another embodiment of the above remediation applications is the introduction of silica gel into the waste zone as the pore filling agent this can be accomplished via infiltration or impregnation of an aqueous alkali silicate solution to which a suitable gelling agent.