The Role of Geocrete and Soluble Sodium Silicate as a Substitute to Control Leachate Leaking from Landfill Side Wall

Geocrete와 규산소다액을 이용한 매립지 사면 침출수 누출제어

There are two strategies to cope with the troubles in landfill site after closure. The first method is active in a way that the wastes are dug up and the recyclable materials are reutilized, meanwhile the materials not recyclable are incinerated in order to minimize the volume of residues to be disposed of. The second method is rather passive and defensive in a way that the source of contamination, that is, buried wastes are not treated. Instead, the transport of leaking leachate and gases generated from the wastes are intercepted and controlled. In this study, as a passive way of the efficient leachate blocking process, applicabilities of geocrete and soluble sodium silicate as a substitute to control leachate leaking from landfill sidewall were investigated. In case of compression test, the strength of mixture I (Geocrete:Sodium silicate=1:3.9 v/v) and mixture II (Geocrete:Sodium silicate=1:2.5 v/v), even after 7 days' curing was higher than the minimum allowance to tolerate the loading(5 kg/$\textrm{cm}^2$). Soaking in the acid fur 4 days and 7 days respectively, the compressive strength of the specimens reduced seriously. The toxicity of geocrete is not detected through the bioassay test, once it was mixed with sodium silicate and the complex was formed. The hydraulic conductivity of the mixtures even after 7 days' curing was lower than the threshold limit $(1.0\times10_{-7}cm/s)$.

비위생매립지 정비방안은 현장에 매립된 폐기물을 파내어 재활용 여부에 따라 처리방법을 달리하는 능동적 방법과 토질 역학적 안정을 피하여 사면부 불안정으로 야기되는 붕괴 및 폐기물, 침출수, 가스의 외부유출을 방지하는 수동적 방법이 있다. 이 논문에서는 매립지 사면부 붕괴에 따른 침출수 유출을 방지하기 위한 수동적 방법으로서의 지오크리트와 규산소다액의 적용가능성을 조사하였다. 배합비 I (지오크리트:규산소다액=1:3.9)과 배합비 H (1:2.5)의 7일 압축 강도는 5.95kg/$cm^3$, 17.05kg/$cm^3$으로 각각 나타나 매립지 공사 최소 허용강도인 5kg/$cm^3$을 상회하였다. 내산성시험 결과, 배합비 I, II의 압축강도는 급격히 감소하였다. 지오크리트와 규산소다액의 환경 독성을 판단하기 위한 어독성시험 결과, 주변환경에 대한 영향은 없는 것으로 나타났다. 한편 투수시험 결과, 배합비 I, II 모두 매립지 허용기준 $(1.0\times10_{-7}cm/sec)$을 만족하였다.