an average of 20 households in each community. At stage 4, a list of households in each community was obtained with the help of local project management officers and the team randomly picked up the households from the household list. Finally, a total number of 223 households were selected and interviewed and 221 households fully completed the questionnaires. Among the total of 223 households surveyed, 110 households are from where a waste collection and disposal system is available and the county capital is located, and the remaining 113 households are from towns which are proposed to be covered by the project (specifically, 32 from Sanyinxiang, 25 from Niujiexiang and 56 from Fengyuxiang). Among the 110 households which are covered by the existing system, 37 are located near to the existing garbage dumping site.

The survey questionnaire was developed by two authors of this paper with help from the local project team people. The final version of the questionnaire includes four parts: socioeconomic characteristics, environmental perceptions and attitudes, questions concerning the current situation of Eryuan residential solid waste collection and disposal and the proposed project, and finally the MBDC contingent valuation questions regarding the WTP to support the project. Repeated pre-tests and focus group discussions are organized to better understand the potential issues associated with the questionnaire presentation and the survey implementation.

Five specifically trained enumerators from Yunnan University, who can understand the local dialect and participated in the focus group studies and the survey pretests, conducted the in-person interviews in July 2007. Cares were specifically taken that only the heads of households selected should be interviewed, who were aware of overall situation of household income and expenditure and could determine the additional expenditures of the households. In the in-person surveys, respondents completed the questionnaires independently but with close guidance of enumerators.<sup>13</sup> Neutrality as well as anonymity of the survey was ensured at the beginning of each survey. Each survey was completed in about 20-30 minutes. At the end of each field day, field coordinators checked the returned questionnaires for completeness and accuracy according to a quality checklist.

The WTP question was presented as follows: As you may know, along with economic growth and population expansion, residential solid waste has become more and more frequently a social and environmental problem that affects the quality of life. Currently in Eryuan County, the residential solid waste is collected, transported and then simply dumped in a garbage dump site located in Sanyingxiang. The odor of the garbage affects the surrounding neighborhood and the school.

Now, Eryuan county government is considering building a new sanitary landfill in Shanglongmen, which is located in the southwest of Eryuan. With special considerations on location choice and necessary equipments, this new landfill infrastructure will have no negative impacts on the health of the nearby residents, nor on local environment. At the same time, besides continuing the collection of the solid wastes of Eryuan county town, the new project will also expand the solid waste collection and disposal service to cover Sanyingxiang,

> 13 The major intention in doing so is to minimize the potential interviewer bias. The interviewers read another copy of identical questionnaire to the respondents, but cannot directly work on the questionnaire that a respondent is working on, and the respondents do not need to speak out their answers to the interviewers. But just like with a mail survey, the final quality of the questionnaire completion cannot be controlled by the enumerators.

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