共查询到20条相似文献,搜索用时 15 毫秒
1.
Liner design for waste disposal sites 总被引:5,自引:0,他引:5
Since the beginning of the 1980s waste disposal has become a particularly sensitive issue. This has led to the development
of new legislations in the European Community and internationally which resulted in an array of regulations concerning landfill
liner design. This paper comments on different "engineered" containment methods with particular reference to landfill liner
design. Suggestions based on the review of the different methodologies are given and a case study is presented.
Received: 25 February 1997 · Accepted: 16 December 1997 相似文献
2.
Two waste-disposal sites (old and new) in Calabar Municipality, SE Nigeria were evaluated to assess their suitability as
landfill sites and their impact on the groundwater. The field investigation included surface geological/hydrogeological and
geochemical studies. Leachate and groundwater were sampled and analysed for 3 months (April, May and June, 1997) for geochemical
characterisation. The results indicate that the two waste-disposal sites in the Calabar Municipality do not meet the requirements
as landfill sites. Physico-chemical analyses for temperature, pH, conductivity, dissolved oxygen, biological oxygen demand
after 5 days of incubation (BOD5), sulphate, nitrates, nitrite, trace and major elements in the leachate known to impact human health and the environment,
indicate high levels of pollution. The values for groundwater in the vicinity of the disposal sites were found to be within
the World Health Organisation (WHO) permissible limit.
Received: 29 March 1999 · Accepted: 3 January 2000 相似文献
3.
E. M. Frempong 《Environmental Geology》1999,37(3):255-260
An engineering geological investigation has been undertaken of a proposed landfill site in coastal southwestern Ghana which
is characterized by torrential rains, high relative humidity, shallow groundwater conditions and almost surrounded by a ridge.
The study shows that the site has some desirable characteristics such as availability of suitable soils for the construction
of the capping and bottom liners of the landfill, a large tract of land for landfilling operation and its location close to
a major highway. However, the groundwater table was shallow and there was a high potential for leachate intrusion into and
consequent contamination of nearby groundwater abstraction wells and surface potable water sources thereby constituting serious
threat to life. Construction costs could be prohibitive as extensive dewatering and backfilling of vast portions of the project
site would be required to enable the provision of a separation between the shallow water table and the bottom of the landfill.
Received: 20 January 1998 · Accepted: 26 May 1998 相似文献
4.
Drill cores from a Bavarian hazardous waste landfill were investigated for their mineralogical composition. Because of the
formation of many new minerals, geochemical equilibrium calculations were performed to find the most stable state of the waste
body. A comparison of mineralogical observations and geochemical modelling was undertaken. The remaining solubilities of the
newly formed secondary mineral assemblages were calculated. Newly formed minerals were shown using electron microscopy.
Received: 26 November 1999 · Accepted: 15 May 2000 相似文献
5.
Integrated use of hydrochemistry and resistivity methods in groundwater contamination caused by a recently closed solid waste site 总被引:6,自引:0,他引:6
In order to investigate the groundwater contamination by solid waste disposal using both hydrochemical and geophysical methods,
the Halkalı (I˙stanbul) solid waste disposal site which was closed in 1994 was investigated. The disposal site lies on a ridge
between two valleys filled with alluvium. A total of six boreholes were drilled on two lines across the Menekşe valley adjacent
to the Halkalı site. Groundwater samples collected from these boreholes were analyzed for various contaminant parameters.
The results indicate that TDS and chloride concentrations decrease horizontally away from the waste site whereas they increase
with depth. Electrical soundings carried out at 12 locations yielded high resistivity values at the upstream part of Menekşe
valley while lower values were obtained from the locations near the leachate seepage points.
Received: 11 November 1997 · Accepted: 23 February 1998 相似文献
6.
A field survey and modelling of the oxidation and carbonate buffering reactions inside the alum-shale-containing waste rock
dumps located in Maardu, Estonia, was accomplished. In the slope areas, the shale has been altered at high temperatures due
to the spontaneous combustion and the pyritic acidity has been eliminated through migration of SOx gases out from the dump. In the central parts of the waste rock plateaus, low temperature pyrite oxidation fronts develop
towards the dump depth and towards the centres of individual shale lumps. The main secondary phases precipitating in the weathering
profile are gypsum, ferric oxyhydroxide, K-jarosite and smectite. The respective field data made it possible to calibrate
the two-stage oxygen diffusion model and the characteristic pyrite oxidation rate 0.06–0.08 mol of pyrite reacted per kg of
available water (pyrox/H2O value) was estimated to describe the first tens of years of dump performance. The model is capable to compare different
shale disposal strategies that are illustrated with two case scenarios. The buffering of sulphuric acid by Mg-calcite appears
to be an incongruent reaction with gypsum precipitating that leads to the build-up of the high Mg/Ca ratio in the leachate.
Application of the Mg/Ca method estimates the pyrox/H2O value in the range of 0.05–0.14 mol/kg.
Received: 26 January 1999 · Accepted: 23. February 1999 相似文献
7.
The Nanjido Landfill is the largest uncontrolled landfill in Korea and it causes various kinds of environmental problems.
Landfill gases and leachate are recognized as the most serious environmental problems associated with the landfill. This study
employs a series of numerical models and uses test data to interpret the distribution and flow of landfill gases and leachate.
Leachate seepage appears about 40–60 m higher than the estimated basal groundwater table. Thus, seepage data indicate that
perched or floating leachate layers are formed in the unsaturated zone of the landfill. The leachate production rate is estimated
using infiltration test data and a model for unsaturated groundwater flow. Geochemical data indicate that the landfill leachate
degrades the basal groundwater quality along the downgradient zone. The environmental impact of the leachate on river water
is estimated.
Received: 17 June 1996 · Accepted: 2 October 1996 相似文献
8.
Cover systems are widely used to safeguard landfills and contaminated sites. The evaluation of the water balance is crucial
for the design of landfill covers. The Hydrologic Evaluation of Landfill Performance (HELP) model of the US Environmental
Protection Agency was developed for this purpose. This paper discusses some limitations of version 2 of this model and some
operational difficulties for the use of this model in Germany, which has been developed for the United States. The model results
are tested against field data of the water balance, measured on test fields on the Georgswerder landfill in Hamburg. Theoretically,
HELP considers gravitational forces as driving forces of water flow only. Therefore capillary barriers cannot be simulated.
Furthermore, the formation of and the flow through macropores are not considered, a main critical process that the diminishes
the effectiveness of compacted soil liners. In the output comparison, the matching of measured and simulated data is quite
good for lateral drainage, but failed for surface runoff and liner leakage through compacted soil liners. A further validation
study is planned for HELP version 3 using a broader range of test field data.
Received: 10 January 1995 · Accepted: 14 November 1995 相似文献
9.
Analysis of flow behavior in a landfill with cover soil of low hydraulic conductivity 总被引:1,自引:1,他引:1
Y. -S Jang 《Environmental Geology》2000,39(3-4):292-298
This paper presents the results of field tests of hydrologic parameters in a landfill and the results of numerical simulation
to find the efficiency of the pumping method to reduce leachate levels in the landfill. The field hydraulic conductivity and
storativity of waste and buried cover soils in the landfill are measured by pumping and slug tests. The hydrologic condition
inside the landfill is first calibrated using the drawdown-time curve obtained from the pumping test, and the flow behavior
of leachate during pumping in the landfill, when various layers of waste and buried cover soil exist, is analyzed through
three-dimensional numerical simulation of flow. The results of the field investigation show that the buried cover soil of
low hydraulic conductivity forms an impermeable layer preventing the downward flow of leachate and upward flow of landfill
gas. The hydraulic conductivities of the pumping test and slug tests were quite close on the same order of magnitude. It was
also possible to match the drawdown-time data of the field tests with those of the model using input data close to the hydrologic
property obtained from the field tests. The numerical flow analysis showed that pumping was possible up to 120 tons/day for
a single well without a drain, while the pumping rate could be increased to 300 tons/day for the same well with the drain.
From the vertical section of the flow vector with a horizontal drain, the barrier role of buried cover soil is identified,
which was proposed by examining the water contents of the disposed cover soil and waste in the field.
Received: 15 May 1998 · Accepted: 4 January 1999 相似文献
10.
Chemical composition of landfill leachate in a karst area with a Mediterranean climate (Marbella, southern Spain) 总被引:2,自引:0,他引:2
I. Vadillo F. Carrasco B. Andreo A. García de Torres C. Bosch 《Environmental Geology》1999,37(4):326-332
Between March 1994 and April 1997, the physical and chemical parameters and chemical composition of the urban solid waste
leachate of the Marbella landfill (southern Spain) were determined. The data obtained show an ammonium and sodium chloride
and bicarbonate type, a pH>7 and high mineralization, effectively described by the following parameters: Na+, K+, NH4
+, Cl– and alkalinity. The chemical composition depends on the rainfall: in dry years, the mineralization and component concentrations
have values as much as double those found in normal rainfall years. After storm events, a major and rapid dilution (within
several hours) is seen in the leachate.
Received: 28 January 1998 · Accepted: 2 June 1998 相似文献
11.
Testing the ability of bentonite-amended natural zeolite (clinoptinolite) to remove heavy metals from liquid waste 总被引:2,自引:0,他引:2
The design of environmentally sound liquid waste containment structures has become a crucial task in engineering applications
due to ever increasing groundwater contamination from such sites. Construction of such structures usually requires a bottom
liner of low hydraulic conductivity as part of the design. In order to reduce the hazards associated with liquid wastes including
landfill leachate, bentonite-amended natural zeolite is proposed as an alternative to conventional earthen liners. Among many
contaminants associated with liquid wastes, heavy metals are the most dangerous ones. This paper deals with determining the
ability of natural zeolite to remove heavy metals from aqueous waste. For this purpose, crushed natural zeolite (clinoptinolite)
is amended with commercial powdered bentonite to yield a soil mixture low in permeability and high in ion-exchange capacity.
Leachate from a conventional landfill is used as the percolation fluid. Concentrations of certain heavy metals in the effluent
fluid percolated through the bentonite-zeolite mixture are compared with that of initial leachate. The conclusion is reached
that certain metals are efficiently removed from the influent solution by the soil matrix whereas some ions do not show significant
reduction in concentration. This is attributed to high hydraulic conductivity of the bentonite-zeolite mixture. 相似文献
12.
Validation of the hydrologic evaluation of landfill performance (HELP) model for simulating the water balance of cover systems 总被引:4,自引:0,他引:4
Klaus Berger 《Environmental Geology》2000,39(11):1261-1274
Simulation models can be efficient tools for several tasks especially in planning. In the USA, the HELP model was developed
to simulate the water balance of landfill liner systems, especially of cover systems. HELP version 3 was examined in a German
climate in an extensive validation study, and a German adaptation was developed. The validation study consists of three parts:
a methodological part (meaning, aims and procedure of validation), a theoretical part (comparison of the modelling approach
with the state of science, comparison of documentation, literature and source code), and a practical part (sensitivity analyses
and operational validation). In the operational validation, measured and simulated discharges and actual evapotranspiration
data of test fields on the landfill Hamburg-Georgswerder from 1988 to 1995 were compared. Limitations, weak points, and errors
of the HELP model are shown. The HELP model is a suitable tool for experts in hydrology; but good knowledge of the model and
its behaviour and critical review of the simulation results are essential.
Received: 14 May 1999 · Accepted: 23 September 1999 相似文献
13.
Permeability and its susceptibility to changes with time or exposure to chemicals are major factors in selection of earthen
liners for use in hazardous liquid-waste containment systems. Earthen liners often consist of mixtures including both granular
soil and fine matrix. Six different solid mixtures were tested to investigate the influence of hazardous liquid waste on their
permeability. The granular part of the mixtures included sand and crushed natural zeolite, whereas the matrix was composed
of bentonite and microcement. Highly acidic solutions, bases, leather industry leachate and municipal waste leachate were
used as permeants. Of the mixtures tested, only two mixtures performed well against the attack of chemicals. The testing method
was the falling head system with the compaction mold permeameter. The period of experiments varied from two to eight weeks.
Received: 24 September 1998 · Accepted: 5 January 1999 相似文献
14.
An expert system is developed for evaluating failure potential of cut slopes and embankments. The fuzzy sets theory is used
with the modified Monte Carlo simulation technique to obtain the Slope Failure Potential Index (SFPI) incorporating factors
affecting slope stability, such as geology, topography, geomorphology, precipitation, vegetation and drainage conditions.
The developed Cut Slopes and Embankments Expert System (CSEES) includes a classification system for evaluating failure potential
of cut slopes and embankments, and a data bank on landslides in Jordan. The proposed classification system and slope failure-potential
method proved to be successful for the areas that experienced landslides in the past. The expert system can be used directly
for areas with the same geological formations as those areas in which landslides occurred in the past and can be used for
areas with other geological formations by modifying the rock type or foundation-material type factor incorporated in the expert
system.
Received: 18 February 1998 · Accepted: 19 October 1998 相似文献
15.
16.
Distribution and environmental impact of coal-mining wastes in Upper Silesia, Poland 总被引:8,自引:0,他引:8
About 50 million tonnes/year of waste rock from coal-mining is generated in the limited area of the thickly populated Upper
Silesian Coal Basin (USCB) in Poland. There are 380 coal-mining waste dumps, including 76 active dump sites covering over
2,000 ha. About 15-16 million tonnes/year of waste rock is being reused for civil engineering purposes in the same area. This
brings about a problem of ground water deterioration by constituents leached from waste rock exposed to atmospheric conditions.
The major factors determining the ground water contamination potential from waste rock are chloride salinity, sulfur content
and acid generation potential. The concept behind the presented studies was to provide data for correct evaluation and prediction
of contaminant release from the waste rock, based on the characterization of coal-mining waste properties, as well as on long-term
laboratory, lysimetric and field studies. The results show that coal-mining waste dumps can be a long-term source of ground
water contamination, lasting for decades and increasing with time. Ground water down-gradient from the disused 15–30-years-old
part of the studied dump displays high and increasing acidification, high TDS, SO4, and the highest, still increasing concentrations of Mn, Fe and Zn. Cost-effective and efficient pollution control measures,
similar to the presented design and construction elements of the dump site, can mitigate the negative environmental impacts.
Received: 3 July 1997 · Accepted: 9 September 1998 相似文献
17.
Scale aspects of groundwater flow and transport systems 总被引:3,自引:1,他引:2
Wouter Zijl 《Hydrogeology Journal》1999,7(1):139-150
Flow-system analysis is based on the concept of hierarchical groundwater flow systems. The topography of the water table, which is strongly related to the topography of the land surface, is a major factor in the hierarchical nesting of gravity-driven groundwater flow, resulting in flow systems of different orders of magnitude in lateral extent and depth of penetration. The concept of flow systems is extremely useful in the analysis of spatial and temporal scales and their mutual relationships. Basic equations on the laboratory scale are extended to larger, regional scales. Making use of Fourier analysis further develops Tóth's original idea of topography-driven flow systems. In this way, the different spatial scales of the water table are separated in a natural way, leading to a simple expression for the penetration depth of a flow system. This decomposition leads also to the relationship between spatial and temporal scales. Analogous to flow systems, water bodies with different water quality may be called 'transport systems.' Field studies, numerical micro-scale modeling over macro-scale domains, and stochastic dispersion theory indicate that between systems with steady transport, the interfaces are relatively thin. The interfaces are much thinner than the relatively large mixing zones predicted by the conventional engineering approach to macrodispersion, in which relatively large, time-independent macrodispersion lengths are applied. A relatively simple alternative engineering approach is presented. For macrodispersion of propagating solute plumes, the alternative dispersion term gives the same results as the conventional engineering approach and gives correct results for steady-state transport. 相似文献
18.
Geophysical investigations using 2-D DC resistivity were carried out on old parts of two similar landfills, with waste of
different ages. The data sets, which included high data density in both vertical and horizontal directions, were interpreted
with 2-D smoothness constrained inversion. The landfills were excavated after the surveying. The objective was to test the
capability of the resistivity method as a pre-characterization technique. The objectives were only partially fulfilled. First,
the moisture content was the parameter that appeared to exert the dominant control over the resistivity distribution of the
landfill. The most important potential information that can be recovered is, therefore, an indication of the waste piles hydraulics.
Second, it was neither possible to estimate the amount of recoverable soils, nor to correlate the type of waste with the resistivity
models. However, discrete anomalies were identified, and if specific materials are searched for, the resistivity models indicate
possible places to search.
Received: 23 July 1998 · Accepted: 20 October 1998 相似文献
19.
An integrated geochemical and toxicological assessment of environmental mercury contamination and attendant human exposure
in Honda Bay, Palawan was undertaken in 1995 following a nationally reported pollution scare centered on a coastal jetty,
Sitio Honda Bay, constructed using approximately 1 million tons of tailings and beneficiation waste from a cinnabar mine.
Mercury (Hg) data for marine and fluvial sediments, fish tissues and human hair indicate that the toxicological hazard is
considerably lower than initially reported by state environment and health officials. Typical Hg concentrations in surficial
Honda Bay sediments were found to lie within the global background range (<60 μg/kg). Downcore profiles provide no evidence
of enhanced Hg fluxes coincident with the onset of mining and/or coastal tailings disposal. The mean and median Hg concentrations
recorded in tissues of six species of Honda Bay fish are compliant with thresholds established by the US Environmental Protection
Agency (US-EPA) for marketable stocks. Earlier reports of 'Minamata range' Hg concentrations in fish and shellfish from Honda
Bay remain unsubstantiated. Geochemical analyses of samples of the Sitio Honda Bay substrate have confirmed the prevalence
of solid-phase Hg concentrations to ca. 340 mg/kg. The speciation of Hg is, however, dominated by secondary oxides of low
bioavailability. The mean Hg concentration in hair from Sitio Honda Bay residents (4.41 mg/kg) was found to be statistically
analogous to that for a neighbouring coastal community unimpacted by the coastal disposal of mine waste. A negligible residential
exposure factor is thus inferred for the former. Relatively high hair Hg burdens prevail throughout the coastal Honda Bay
population, consistent with significant methyl Hg ingestion through daily fish consumption. The data presented provide no
environmental or toxicological justification for immediate remedial action.
Received: 14 May 1998/Accepted: 1 September 1998 相似文献
20.
Water vulnerability assessment in karst environments: a new method of defining protection areas using a multi-attribute approach and GIS tools (EPIK method) 总被引:42,自引:12,他引:30
Groundwater resources from karst aquifers play a major role in the water supply in karst areas in the world, such as in Switzerland.
Defining groundwater protection zones in karst environment is frequently not founded on a solid hydrogeological basis. Protection
zones are often inadequate and as a result they may be ineffective. In order to improve this situation, the Federal Office
for Environment, Forests and Landscape with the Swiss National Hydrological and Geological Survey contracted the Centre of
Hydrogeology of the Neuchatel University to develop a new groundwater protection-zones strategy in karst environment. This
approach is based on the vulnerability mapping of the catchment areas of water supplies provided by springs or boreholes.
Vulnerability is here defined as the intrinsic geological and hydrogeological characteristics which determine the sensitivity
of groundwater to contamination by human activities. The EPIK method is a multi-attribute method for vulnerability mapping
which takes into consideration the specific hydrogeological behaviour of karst aquifers. EPIK is based on a conceptual model
of karst hydrological systems, which suggests considering four karst aquifer attributes: (1) Epikarst, (2) Protective cover,
(3) Infiltration conditions and (4) Karst network development. Each of these four attributes is subdivided into classes which
are mapped over the whole water catchment. The attributes and their classes are then weighted. Attribute maps are overlain
in order to obtain a final vulnerability map. From the vulnerability map, the groundwater protection zones are defined precisely.
This method was applied at several sites in Switzerland where agriculture contamination problems have frequently occurred.
These applications resulted in recommend new boundaries for the karst water supplies protection-zones.
Received: 27 October 1997 · Accepted: 4 July 1998 相似文献