Test Area Location. The proposed test area measures 160 feet by 200 feet and is located within the southwestern portion of Subcell 8-4 (see Attachments IV and VIII). The waste volume in this area is approximately 95,500 cubic yards (waste depth from surface to liner is approximately 80 to 85 feet). The test area is a plateau with a 2 percent slope toward the landfill s side slope. The test area is adjacent to an existing haul road which makes it accessible to tank trucks for easier liquid injection. The County determined that this area had the best conditions for the bioreactor pilot project. Subcell 8-4 began accepting MSW in October 1992. The site has accepted only small quantities of curbside MSW since 1997; it now accepts primarily construction debris. Thus the lowermost portion of the waste in Subcell 8-4 contains typical MSW, while the uppermost portion contains waste that is proportionately higher in construction debris and lower in decomposable organic materials. The County recently completed (summer 1999) a waste composition study to provide more detailed information about recent waste placement in the area of the proposed test. A March 1995 waste sort report will also be consulted. The County used soil as a daily cover at the site until March 1993. Since then, the County has primarily used removable and reusable tarpaulins (tarps) throughout Cell 8 as the cover (approximately 97 percent of the time, depending on weather conditions). Previous use of tarps (rather than soil cover, for example) presents good conditions for a bioreactor study, as there is less potential for the creation of barriers (e.g., compacted soil cover) to limit vertical penetration of liquid into the waste mass. The base liner for each constructed Subcell in Cell 8 is a double synthetic system consisting of the following, from top to bottom (refer to Attachment VI):
Test Area Location. The proposed test area measures 160 feet by 200 feet and is located within the southwestern portion of Subcell 8-4 (refer to Attachment IV). The waste volume in this area is approximately 95,500 cubic yards waste top elevation is approximately 218 feet and bottom elevation is between 135 and 140 feet) and the depth is approximately 80 to 85 feet. The test area is a plateau with a 2 percent slope toward the landfill’s side slope. The test area is adjacent to an existing haul road which makes it accessible to tank trucks for easier liquid injection. The County determined that this area ha d the best conditions for the bioreactor pilot project. Subcell 8-4 began accepting municipal solid waste (MSW) in October 1992; Subcell 8-6 accepted waste beginning in September 1997. The site has accepted only small quantities of curbside MSW since 1997; it now accepts primarily construction debris. Thus the lowermost portion of the waste in Subcell 8-4 contains typical MSW, while the uppermost portion contains waste that is proportionately higher in construction debris and lower in decomposable organic materials. The County recently completed (summer 1999) a waste composition study to provide more detailed waste stream information. A March 1995 waste sort report will also be consulted. The County used soil as a daily cover at the site until March 1993. Since then, the County has primarily used removable and reusable tarpaulins (tarps) throughout Cell 8 as the cover ( approximately 97 percent of the time, depending on weather conditions). Use of tarps for a bioreactor study is ideal, as there is less potential for the creation of barriers (e.g., compacted soil cover) to limit vertical penetration of liquid into the waste mass while data is being collected. The base liner for each constructed Subcell in Cell 8 is a double synthetic system consisting of the following, from top to bottom (refer to Attachment VI):
