ABSTRACT: The leachate containment system is the most critical and expensive element of the landfill ... The protection of groundwater against leachate of old.
Groundwater Protection System for Old Landfill Leachate Containment System des Grundwasserschutzes vor Rückflüssen von alten Versturzplätzen Dr. Koda, Eugeniusz – Department of Geotechnical Engineering SGGW, Warsaw, Poland
ZUSAMMENFASSUNG: Das Protektionsystem, das die Rueckfluesse schliesst, ist ein den wichtigsten und teuersten Elementen von dem Bau von einem Sturzplatz, besonders fuer alte Sturzplatze. In Artikel wurden die mit Gruntwasserprotektion verbudenen Loesungen presentiert. Diese Loesung wurde auf zwei Sturzplaetze in der Naehe von Warschau benutzt. Die Gruntwasserprotektion vorRueckfluesse von alten Sturzplaetze kan mit Benutzung von vertikalen Antifiltrazionbarrieren und Draenage reaslisiert werden. Mit solcheinem System sind die Rueckfluesse isoliert – von Seite durch die Barriere und von unten durch die natuerliche undurchlaessige Schicht. ABSTRACT: The leachate containment system is the most critical and expensive element of the landfill construction, particular for that old one. The paper presents groundwater protection solutions used for two old sanitary landfills found nearby Warsaw. The protection of groundwater against leachate of old landfills can be realised by the cut-off wall and peripheral drainage (pipe drains or drainage trench, “finger” drains). This system allows leachate to flow freely to the water table zone, which is contained by a perimeter cut-off wall barrier and natural geohydrologic barriers. It enhances containment by including a counterflow condition, in which “clean” groundwater flows towards the polluted zone and will also protect the bentonite material against degradation, caused by the leachate. Introduction Both, landfills and other waste utylisation facilities are the main sources of the high leachate pollution, particularly in old landfills when the leachate transport in subsoil has been continued for many years. If not designed properly, this leachate may pollute groundwater, soil and surface water. Remedial works on old sanitary landfills need the solution of many problems in the framework of geotechnics (1, 2). Particular attention must be paid to old landfills to protect against groundwater pollution by leachate. This is connected with the design of drainage systems, completed by the cut-off wall barriers. Development of proper drainage system should be proceeded by long-term experience, taking into consideration specific properties of the sanitary landfill leachate. The leachate from drainage can be partly utilised on the landfill or discharged to a treatment plant and then surface streams.
The paper describes solution designs and observation of effectiveness of groundwater protection systems in the two selected old landfills found nearby Warsaw, i.e. Radiowo and Łubna. Effective remedial works are based on precise definition of the landfill conditions as well as its closer and further vicinity. The submerged counterflow system consists of a bentonite cut-off wall barrier in order to protect the first aquifer against the transport of pollutants. In the framework of the remedial design, the peripheral drainage around the landfills was constructed (Figure 1). Moreover, at the bottom of berms, the “finger” pipe drains were also installed so that to direct the leachate to the peripheral drainage. A peripheral drainage sink recovers leachate. This design enhances containment by including a counterflow condition, in which clean groundwater flows towards the contaminant zone. This system is effective, easy to design and build, reliable for environment protection, and applicable to various site conditions.
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Figure 1. Scheme of the groundwater protection system against the transport of pollutants from old landfill (cut-off wall and drainage system). Old landfills threat Sites characteristics The threat resulting from old landfills mainly Radiowo landfill is located in the north-west depends on: hydrogeographical and part of Warsaw. Since early 60’s to 1991 the hydrogeological conditions, age and kind of landfill was used as a place, where municipal wastes as well as the methods of waste disposal. wastes from Warsaw were disposed. Actually, it Effective remedial works should be based on covers ca. 15 ha area, and it is higher than 55 m. precise definition of the landfill condition, its It is planned to be closed in the year 2005. Now, closer and further vicinity. Basic investigations only non-composted wastes from Radiowo of old sanitary landfills should mainly include: compostory (the biggest in Poland) are stored on study of exploitation files (if any) defining the landfill. The organic matter content for nonthe kind and age of wastes as well as composeted wastes is ca. 4% (3). Central and unpredictable events (fire, landslides, etc.); south parts of the landfill are filled with 10-30 waste disposal survey; years of old municipal wastes, while the upper hydrogeological conditions; layers in the north part are filled with fresh non evaluation of waste mechanical parameters; composted products. This significant difference description of protected areas and objects in between the two kinds of wastes stored on the vicinity of landfill (if any); landfill influences the diversification of leachate. assessment of gas volume. Subsoil consists of sands the thickness of 2-15m, The above mentioned information is necessary underlayed by boulder and Tertiary clays. for designing the remedial works. Advantageous Groundwater level is at the depth of 0.2-1.0m. landfill location conditions are such, when in the Łubna landfill is located at the distance of subsoil there is a natural continuous aquitard layer approximately 35km to the south of the centre of (thickness min. 3 m, permeability k
