• KOREAN JOURNAL OF CROP SCIENCE
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• v.57 no.3
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• pp.238-247
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• 2012

To determine the possibility of solidified se wage sludge for use as a soil cover material in reclaimed land, the growth of energy crops and soil chemical properties investigated in each experimental plots during 2 years (2010 and 2011). The experimental plots consisted of the mixing with solidified sewage sludge plot (SS50), the covering with solidified sewage sludge plot (SS100), and the original reclaimed land plot (ORL) on reclaimed land for the intended landfill in Sudokwon Landfill Site Management Corporation (SLC). Plant height, measured in the second year (2011), was highest in the Geodae 1 grown at plots treated with solidified sewage sludge. The growth of energy crops cultivated in both SS50 and SS100 were better than in ORL. The contents of organic matter (OM) and total nitrogen (T-N) at both SS50 and SS100 were considerably higher than that of the ORL over 2 years. However, the soil from ORL showed higher salinity with high contents of exchangeable $Na^+$ cation than that of SS50 and SS100 over 2 years. We consider that soil chemical and physical properties on reclaimed land used in this study could be improved by the application of solidified sewage sludge due to following reasons. Firstly, the application of solidified sewage sludge may provide soil nutrients on reclaimed land i.e. the growth of energy crops better than in ORL, resulted in more OM and T-N contents in SS50 and SS100. Secondly, the top layers mixed or covered with solidified sewage sludge on reclaimed land may be prevented the salinity accumulation due to capillary rise to surface soil, and improved the cultivation layer for effectively propagating the rhizomes of energy crops. Thus the solidified sewage sludge may be a great soil cover materials for cultivation of bioenergy crops in reclaimed land.

• Journal of the Korean Society of Safety
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• v.14 no.4
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• pp.135-141
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• 1999

This study is an experimental study to investigate the possibility of the utilization of paper ash as the cover, liner in waste disposal landfill and other construction materials. The sample used in these tests was obtained from Daehan paper mill. A series of tests were peformed to evaluate basic properties, compaction, permeability, compressive strength, consolidation, leaching, and CBR of paper ash. In order to investigate the soil engineering properties of paper ash, the test results were compared with those obtained of fly ash. The results of unconfined compression tests show that paper ash had a larger strength than the fly ash. Also, the maximum dry unit weight of paper ash was approximately 59～76.9% less than that of the fly ash. It was found from the results of leaching test that paper ash is classified as non-detrimental general wastes according to the waste management law.

• Proceedings of the Korean Geotechical Society Conference
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• 1995.10a
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• pp.15.1-20
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• 1995

일반적으로 일반 및 유해폐기물 매립지에서 진흙층의 기능적 수행목적은 다음과 같다고 할 수 있다. 지표면 유출의 증진을 위하고, 우수의 침투억제 및 폐기물의 표면 노출 시 완충작용, 따라서 최종복토의 붕괴는 이러한 중요 기능을 마비시키고 있다. 본 연구는 추운 날씨상태의 폐기물 매립지 최종복토의 거동을 수행하였으며, 실제로 설계된 세 개의 거대한 실험실 Tank에서 복토에 대한 실험이 시행되었다. 이 거대한 실험장비의 제원은 0.75m x 2.4m와 2.0m 깊이로 되어 있다. Tank안은 시방서적으로 폐기물 매립지가 요구하는 진흙층과 최종복토를 위한 물질로 채워졌다. 그들의 실험결과는 동질/융해에 따른 진흙과 복토층의 붕괴현상은 물리적, 공학적인 측면에 영향을 주는 것으로 나타났다. 본문은 실험에 사용된 복토층의 묘사, 그들의 실험결과들과 실험을 통한 결과분석 및 결론을 설명하고 있다. 실험결과로서는 각 모형들의 우수와 침출수 자료, 온도변화의 배경과 최종복토에서의 Water Balance를 포함하고 있다. 또한 결과로서 시험된 세 개의 모형들은 매립지에서의 동결깊이(29cm~32cm)를 나타내주며 그들 중 하나의 모형은 배수층을 가지고 있어 침출수억제에 효과적이므로 다른 모형보다 복토층으로서 우위에 있다는 것을 지적하고 있다.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.672-679
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• 2008

During recent years, the large soft ground improvements very rapidly increase with industrial development and it is the types and scales of structure that is enlarged by degree. Then, we must enter construct equipment to improve soft ground and we fulfilled works by carrying out soft clay soil to gain trafficability for them. For improving the soft ground, we lay geotextile on soft clay ground and fill the filter sand that can drain the pore water. Then, we landfill cover soil for come by trafficability of construction tools. Ater that we penetrate vertical drain for dehydration through soft ground. there are very complicated works. For these reason we suggest the methods of soft ground improvement constructions.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.177-184
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• 2003

매립장 내의 설치된 중간 복토층(intermediate cover)은 매립 도중 혹은 매립완료 후 종종 침출수가 하부의 침출수 집배수관으로 이동하는 것을 막아 매립장 내에 일정 침출수위를 형성시킨다. 이렇듯 중간 복토층은 침출수의 원활한 순환을 막아 매립장 바닥에 형성되어야 하는 침출수위가 중간복토층 위에 형성되도록 하는데, 이는 매립장의 구조적 안정성을 깨뜨리고 주변으로 침출수 누출을 유발시키게 된다. 본 연구에서는 이처럼 중간복토층 상부에 형성된 침출수위를 저하시키기 위하여, 폐기물 매립시 중간복토층에 투수성이 뛰어나고 역학적 강도와 화학적 내구성을 갖는 배수파일(Drain Pile)을 설치할 것을 제안하였다. 배수파일은 중간복토층 상부에 형성될 수 있는 침출수를 매립장 바닥으로 배수시키고, 침출수 집배수정으로 이송이 가능하게 만든다. 또한 배수파일은 매립장 내부에 설치됨으로써 폐기물의 자체 강성을 증가시키고, 동시에 매립장의 측방유동을 막아 구조적 안정성을 확보하는 효과도 기대할 수 있다. 실내시험을 통해 배수파일 충진재로서 굴패각의 활용가능성을 확인한 결과, 산업 폐기물인 굴패각이 침출수의 pH를 중화시키고 유해물질인 NH$_{4}$$^{+}$를 제거하는데 효과적임을 확인할 수 있었다. 한편, 실제현장의 침출수흐름을 모사하기 위해 범용 프로그램(SEEP/W)을 이용하여 매립지 내에서 배수 파일의 효과를 확인하였다.

• Journal of the Korean Geotechnical Society
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• v.15 no.2
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• pp.43-71
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• 1999

This research is an experimental work of developing a construction material using municipal wastewater sludge as liner and cover materials for waste disposal landfill. Weathered granite soil and flyash, produced as a by-product in the power plant, were used as the primary additives to improve geotechnical engineering properties of sludge. For secondary additives, bentonite and cement were mixed with sludge to decrease the permeability and to increase the shear strength, respectively. Various laboratory test required to evaluate the design criteria for liner and cover materials, were carried out by changing the mixing ratio of sludge with the additives. Basic soil properties such as specific gravity, grain size distribution, liquid and plastic limits were measured to analyze their effects on permeability, compaction, compressibility and shear strength properties of mixtures. Laboratory compaction tests were conducted to find the maximum dry densities and the optimum moisture contents of mixtures, and their effectiveness of compaction in field was consequently evaluated. Permeability tests of variable heads with compacted samples, and the stress-controlled consolidation tests with measuring permeabilities of samples during consolidation process were performed to obtain permeability, and to find the compressibility as well as consolidational coefficients of mixtures, respectively. To evaluate the long term stability of sludges, creep tests were also conducted in parallel with permeability tests of variable heads. On the other hand, for the compacted sludge decomposed for a month, permeability tests were carried out to investigate the effect of decomposition of organic matters in sludges on its permeability. Direct shear tests were performed to evaluate the shear strength parameters of mixed sludge with weathered granite, flyash and bentonite. For the mixture of sludge with cement, unconfined compression tests were carried out to find their strength with varying mixing ratio and curing time. On the other hand, CBR tests for compacted specimen were also conducted to evaluate the trafficability of mixtures. Various test results with mixtures were assessed to evaluate whether their properties meet the requirements as liner and cover materials in waste disposal landfill.

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.179-189
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• 2000

The purpose of this research is to complement the existing researches on landfill bottom liners behavior during the periods of freeze and thaw. Landfill-related researches have been typically focused on small-scale soil samples that are often compacted under conditions different from those used in the field. Although these tests have been invaluable in clarifying the problem of freeze and thaw, extending the results of such experimental studies to prototype landfills are questionable. In this investigation, the author utilized a large scale laboratory simulation allowing inclusion of the field depth of the cover systems, layered soil profiles, rainfall simulation, a cold climate and boundary conditions similar to those encountered in the landfill. The soil materials were stabilized soils (mixed clays, cements, and minerals) instead of clays. The bottom liners are made up of drainage layer (30 cm), stabilized layer (75 cm), and leach collection layer (60 cm). The stabilized layers are made up of supporting layer (45 cm) and low permeable layer (30 cm) - consisting of $P_A\; and\; P_B$ layer. As a results, depths of penetration increased by about 2~5 more centimeters at rainfall simulated designs than those at no rainfall simulated designs (that is design 3, design 5 and design 7) - it increased by about 20mm/day in the bottom liners and frost heaves also increased it by a few millimeters. Also, a few cracks appeared partly. According to these results, we can surmise that the compacted stabilized soil is more reliable than the compacted clay liners for construction of the landfill liners.

• The Journal of Engineering Geology
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• v.17 no.1 s.50
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• pp.125-133
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• 2007

The environmental and geotechnical properties are investigated to the 8th landfill area made of only sewage sludge in Nanji-Do. To do this, the soils are sampled in this area, and leaching tests, heavy metal content tests, and so on are performed to research the environmental properties. As the result of heavy metal content tests, Pb, Zn, Cu, Ni, Cd and Cr were leached from the sewage sludge. Because the leaching concentration of Cu is more than the standard value of California state, Cu content have to bring down during the recycling of the sewage sludge. Meanwhile, a series of tests concerning specific gravity, liquid and plastic limits, compaction, permeability and shear strength is performed to research the geotechnical properties. The sewage sludge is consisted of sand, silt and clay, and is classified into non-organic silt or organic clay with 42.3% of plastic index. As the result of compaction test, it is expected that the compaction effect according to variation of water contents is low relatively because the dry unit weight is low and the curve of compaction forms flatness. Also, as the result of direct shear tests, the cohesion is $0.058kg/cm^2$, and the internal friction angle is $14^{\circ}$. Taking everything into consideration, the various problems are happening in case of recycling the sludge like the cover layer of landfill and so on because the compaction is bad, and the shear strength is low. Also, it is expected that the ground water pollution caused by leaching the heavy metal into the sludge. To do recycling the sewage sludge in this site, supplementary and treatment programs should be prepared.

• Journal of the Korean GEO-environmental Society
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• v.4 no.4
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• pp.25-34
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• 2003

This paper is focused on an experimental study in order to investigate the utilization of sewage sludge ash as the cover and liner materials for the waste disposal landfill or as construction materials. A series of tests were performed to evaluate the basic properties, compaction, compressive strength, consolidation, permeability, and CBR of sewage ash. Specially, clay bricks were made as increasing replacement ratio of sewage ash (such as 5, 10, 15, 20, 25, 30%). And tests were fulfilled for its quality. Bentonite and lime were used as the additives to improve permeability properties of sewage sludge ash. As a result of tests, it was shown that the permeability coefficient decreases as increasing bentonite content and the percentage of bentonite was roughly needed 20% to keep the permeability coefficient below $1{\times}10^{-7}cm/sec$. The results of unconfined compression tests show that sewage ash meets the criteria of the unconfined compression strength for cover material. It was shown that the compressive strength decreases as increasing the replacement ratio of sewage sludge ash and the maximum replacement ratio of sewage sludge ash to satisfy the quality standards of the third degree bricks was about 15%.

• Journal of Environmental Impact Assessment
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• v.13 no.4
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• pp.187-196
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• 2004

매립지에서 배출되는 메탄가스는 이산화탄소에 이어 두 번째로 많이 배출되는 지구온난화 가스이지만 열을 흡수하는 능력에 있어서는 이산화탄소 보다 25에서 35배 정도 더 크기 때문에 지구 온난화 현상에 대한 메탄가스의 영향은 중요하다고 할 수 있다. 매립지로부터 배출되는 메탄가스는 호기성 상태의 매립지 복토층을 통과 할 때 산화될 수 있으므로 매립지 복토층은 메탄가스의 배출을 저감시키는 바이오필터의 역할을 할 수 있다. 본 연구에서는 batch 실험을 통하여 매립지 복토층에서의 메탄산화속도에 대한 토양수분과 온도의 영향을 연구하였다. 최대 산화속도는 토양수분 15%(w/w), 배양온도 $35^{\circ}C$의 환경조건에서 $1.03{\mu}mol\;CH_4g^{-1}soil\;h^{-1}$으로 나타났다. 이러한 실험결과를 이용하여 토양수분과 온도를 함수로 하는 회귀모형을 개발하였다. 또한 전국에 4 군데 지역을 선발하여 각 지역의 토양수분과 온도 데이타를 수집하고 개발된 모형을 이용하여 각 지역에 위치하고 있는 매립장에서의 월 평균 메탄산화량을 예측하였다. 예측 결과 환경조건이 양호한 지역의 매립지 복토는 메탄의 배출량을 저감시킬 수 있는 효율적인 바이오필터의 효과를 가지지만 환경조건이 불리한 지역의 매립지 복토에서는 바이오필터의 효과가 크지 않는다고 할 수 있다.