What If? Looking into the future, assuming a growth in tonnage of 175 percent, diversion of 50 percent, and that most of the diversion is into recycling and not composting (90 percent vs. 10 percent), a solution results where almost all landfills are actively used (see Figure 5; red dots indicate actively used facilities). All facilities used in the base case (still indicated with
yellow dots) are in use, and system-wide composting is almost at capacity. The Ostrom Road Landfill, which has no composting capacity, is the only facility not in use. At a higher rate of growth or a greater proportion of diversion to composting, the LP problem becomes infeasible.
Authors’ Note: The mathematical expressions for these primal LP and dual LP problems, along with an Excel implementation using the Excel Solver, are available under “GeoWorld Solid Waste Sustainability 2011” at pogodzinski.net.
J.M. Pogodzinski is professor of Economics at San Jose State University; e-mail: j.m.pogodzinski@gmail.com.
Paul E. Ledesma is the Trash Reduction Program coordinator for the city of San Jose’s Stormwater Management Program; e-mail: Paul.Ledesma@sanjoseca.gov.
lFigure 5. The optimal solution to the MIN-EXP LP problem indicates growth of the solid-waste stream and modest diversion
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