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5-14 monument will be surveyed upon completion of all closure construction activities. In accordance with 27 CCR requirements, Forward Inc. will update the aerial survey of the landfill every five years throughout the post -closure maintenance period. An iso -settlement map and report is to be submitted to the RWQCB included as part of the survey information. 5.3.5 Leachate Generation The majority of the existing WMUs at the Forward Landfill contain a blanket LCRS. However, there is no LCRS underlying the Austin Road Unit and portions of the eastern part of the Forward Unit. There is, however, a LCRS placed above the closed portion of the Austin Road Unit as part of the consolidation of the Forward and Austin Road Units and to allow the placement of additional refuse to the permitted heights. The LCRS calculations for the Forward Landfill development include calculations for LCRS lateral spacing based on infiltration modeling, pipe capacity based on tributary flows, and LCRS pipe wall thickness based on deflection analysis (see Appendix H). The sections that follow present the background and results for the LCRS calculations. Leachate Generation Analyses Modeling of potential leachate generation within the entire planned vertical and horizontal landfill expansion was completed using the United States Army Corps of Engineers 10 Hydrologic Evaluation of Landfill Performance, Version 3.06 (HELP3). This modeling simulated a refuse fill placed over the entire liner development system, including liner placed over existing wastes. Input and output files are included as Appendix H. The calculated rate of leachate generation and accumulation were the primary parameters used in designing the LCRS. F-1 L Model Description and Setup HELP is a quasi -two-dimensional model that simulates moisture flux into and out of landfills. It has become the standard method for evaluating the potential performance of landfill liner and cover systems. The model calculates water balances in daily increments, and can provide output for daily, monthly, and annual values for precipitation, run-off, evapotranspiration, percolation, and lateral drainage. The calculations integrated the user selected variables shown in Appendix H. With the exception of the iterative moisture contents described below, all soil and refuse parameters used in modeling the LCRS are default values selected from the HELP program as typical for municipal solid waste landfills. Weather data was synthetically generated by the program for the Stockton area and corrected for the latitude of the landfill, yielding an average annual rainfall total of approximately 15.5 inches. Forward Landfill SWT Engineering Joint Technical Document - April 2014 z:\projects\allied waste\forward\five year permit rvw 2013\jtd-5 yr pr 2013\text\sec 5_final.doc