Design of vertical landfill gas collection wells considering non-homogeneity with depth. (December 2018)

• Record Type: Journal Article
• Authors: Zheng, Qi-Teng; Rowe, R. Kerry; Feng, Shi-Jin
• Is Part Of: Waste management. Volume 82(2018)
• Page Start: 26
• Page End: 36
• Publication Date: 2018-12
• Subjects: Variable gas permeability -- Variable gas generation -- Vertical well spacing -- Cover properties -- Vacuum pressure -- Design method; Hazardous wastes -- Periodicals; Refuse and refuse disposal -- Periodicals; 363.728
• DOI: 10.1016/j.wasman.2018.10.012
• Languages: English
• ISSNs: 0956-053X

Abstract

Highlights: Identify the design parameters for 90% gas recovery for typical waste properties. Define spacing of vertical wells as a function of vacuum and waste/cover properties. A generalized design method for the spacing considering waste non-homogeneity. Study the effect of waste non-homogeneity in design process with some guidelines. Abstract: Considering variable gas permeability and gas generation of waste with depth, different combinations of cover properties, vacuum pressure, and horizontal spacing of vertical wells giving rise to a 90% gas recovery rate are identified for typical waste properties. The effects of passive and active gas collection on horizontal well spacing are quantified. The normalized well spacing for 90% recovery is examined as a function of the cover resistance and the vacuum pump capacity. Design charts dependent on changes in gas permeability and gas generation rate with depth are presented to aid in the design of vertical gas wells. It is demonstrated that the non-homogeneity in gas permeability of waste is of great importance. For a conservative design, uncertainty in the non-homogeneity in gas permeability should be overestimated while uncertainty with respect to the non-homogeneity in LFG generation should generally be underestimated. The use of the proposed method for the design of the spacing of vertical gas wells in a situation with waste non-homogeneity is illustrated by a practical example.