【正文】 (v) Finally, Member States should develop economic incentives to favor the recovery of methane gas, the use of technologies, and the reduction of the amount of anic matter deposited in landfills. Decision 99/296/CE published on April 26, 1999, modified Decision 93/389/CEE regarding the monitoring of CO2 and other greenhouse gases such as methane. This decision affirms that Member States should make an inventory of the sources of gas emissions and their elimination by drainage sites, as well as describe the policies and national regulations adopted to reduce such emissions, and thus facilitate their total elimination. As can be observed, these regulations are somewhat ambiguous in reference to the measures to be taken for the efficient management of biogas. Nevertheless, what is clear is the message regarding the need to reduce and minimize the negative impact that uncontrolled biogas emission has on the environment. 5 2. An urban waste landfill in Granada (Spain) . Profile of the landfill The landfill studied in this article is located 2 km northeast of Granada, a city in southern Spain with a population of 300,000 inhabitants. The landfill, with a surface area of Has, was in active operation from 1984 to 1999. During this period, the waste was deposited on a hillside running along the river Beiro with an average altitude of 870 and 500 m (see Fig. 1). The landfill is of medium density, and over the years was progressively covered with layers of soil from the same area and similar to that found in the bed of the landfill. The waste pacting process was carried out by means of pacting equipment, with a waste pacting degree of – Tm/m3. The leachate was collected in pools where it was pumped out again to be recirculated in the landfill. The extraction of the gas was carried out by a series of gas extraction wells separated by distances of 30–35 m. In 1999 with a view to mitigating the negative environmental impact, the landfill was sealed. Subsequently, plans were drawn up to construct installations to extract biogas and reuse it to create electrical energy. The project was carried out that same year by INAGRA (pany belonging to CESPA3). The average annual precipitation in this region fluctuates from 66 to 400 mm during the seasons of autumn and winter. The average annual temperature in Granada largely depends on the weather station where the measurements are obtained. The average temperature is 1C as measured at the Cartuja weather station in the city, whereas it is at the airport weather station, 10 km outside the city. The temperature in Granada is influenced by the proximity of the Sierra Nevada mountain range. The highest temperatures occur during the summer months, while the lowest ones occur in December and January. The thermal variation in the average annual temperatures is significant, and amounts to almost 20 1C. This is the same variation that exists between daytime and nighttime temperatures. The potential evapotranspiration of the area, as calculated by the Thornthwaite Method, reaches values ranging from 700 to 900 mm. There is generally a period of draught in the summer months. The landfill is located on the Alhambra formation, made up of conglomerates and sands, immersed 6 in a large clayey basin, reducing the capacity of water transmission in the subsoil. There are no aquifers or signs of surface or groundwater at the landfill site. After the landfill was sealed, urban waste from Granada, as well as that from other neighboring cities and towns, was treated at the Planta de Recuperacio180。 (iii) In the case of new landfills, the permits granted to controlled anaerobic deposits should be strictly monitored. In any case, it is always necessary to verify whether there are other ways of limiting methane emission, and at the same time incorporate highly efficient systems for its reception and energy evaluation。 (iv) Gas should be monitored at each section of the landfill. In those landfills in which gas cannot be reused to create energy, it will be monitored at the site where such gas is emitted or burnt. . Resolution 97/C76/01 on an EU waste management strategy Resolution 97/C76/01 was passed on February 24, 1997. In Article 35 it specifically affirms that members of the European Union should take the necessary cleanup measures to guarantee the restoration of former landfill sites and other contaminated locations to a satisfactory state [25]. 4 . Communication regarding a strategy for the reduction of methane emissions In order to take into account the potential effect of methane emissions on the climate, this munication points out the need to analyze the problems derived from such emissions as well as the need to identify sources and drainage sites. It also underlines the necessity of establishing a mon strategy. This would basically consist of methods of reducing emissions as well as a set of guidelines in this regard that would be incorporated into the legislation of Member States. Among the measures to be implemented would be the establishment of an objective for the reduction of emissions to be achieved in a given time period. The political measures established would be evaluated according to their cost–benefit in terms of potential economic and social consequences. According to a previous study, the main focus should be on those sectors that make the largest contributions to methane emissions, notably agriculture, waste and energy which in 1990 accounted for 45, 32 and 23% of EU methane emissions, respectively. The main source of the methane emissions derived from waste management is the anaerobic fermentation of the anic material deposited in landfills. Communication COM(96)557 includes the following remendations [26]: (i) A distinction should be made between existing landfills