ARCHIVED REPORTS_1996_1 - Laserfiche WebLink

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II. Project Description excavation of approximately 1.9 million cubic yards(mcy)of soils. The proposed excavation and site preparation are shown in Figure 11.3. The excavation for the creek realignment, floodplain and surface water detention facility would result in a total of 2 mcy of soil. The conceptual design indicates that the proposed landfill expansion would require 6.3 mcy of soil materials in total,including approximately 1.8 mcy of clays suitable for the liner and/or final cover,and approximately 4.5 mcy suitable for daily and intermediate cover. For the purpose of determining excavation quantities,it was assumed that a 3:1 ratio of refuse to cover would be required. This is a more conservative estimate than the 4:1 ratio used to determine refuse capacity. There is a material volume loss due to compaction and other operational considerations when the fill is constructed. Soils excavated during construction and suitable for the liner or covers would be stockpiled on site until needed. Some of the materials would be stockpiled on top of the existing landfill after it is properly closed. These stock piles would preload the existing landfill and maximize settlement prior to construction of the vertical expansion. It is also anticipated that preloading the landfill would squeeze out the leachate being collected by a leachate remediation system for the existing landfill. The remaining soils would need to be excavated from the borrow area,imported,and/or an alternative cover would be needed. The current landfill has a problem with applying daily cover during wet weather . because of the difficulty of excavating soils. The operator has submitted an application to the California Integrated Waste Management Board(C )to use alterative daily cover ) material(ADC)(Wickes, 1993). In order to use ADC,the applicant would need to submit a request to the CIWMB and the Local Enforcement Agency )to implement a demonstration program. The request must contain detailed information on the type of ADC selected,an evaluation of the functional properties of the ADC,a comparison of the properties of the ADC with corresponding properties of soil,and information on the site. If the request is approved, C could be used initially on an experimental basis and if,after the program is implemented, the LEA and C B staff find that the material can function as a suitable daily cover,ADC could be used on a non-experimental basis. Details of the base liner for the Austin Road Landfill are shown in Figure IIA. The purpose of the base liner is to contain leachate within the landfill so that it can be channeled and collected. For the horizontal expansion,the base liner would be placed upon the prepared excavation at the site. For the vertical expansion,the base liner would be placed upon the final cover of the • existing landfill. From top to bottom,the typical base liner design includes an 1&inch IN