ARCHIVED REPORTS_POST CLOSURE LAND USE PROPOSAL 2014

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County of Riverside Drainage facilities A network of lined drainage ditches and down chutes is present on the final cover to collect and manage runoff from precipitation events. The northwest portion of the landfill has been designed to drain northerly to a ditch along 26th Street and westerly to Hall Avenue. Storm water ditches on Hall Avenue collect and convey runoff to the drainage ditch adjacent to the southwest portion of the site. Surface drainage from the southwest portion of the site flows to the west, south, and east. An existing drainage ditch conveys flows south from the southwest corner of this portion of the site, then easterly along the southern border to a box culvert under State Highway 60 at the approximate midpoint of the south boundary. The eastern portion of the site is served on three sides by a drainage channel that also drains into the box culvert under State Highway 60. 4 SURFACE PREPARATION AND DESIGN LOADING The site may be stripped of vegetation in preparation for the racking and panel mounting systems. The Project Proponent shall request an MSHCP/nesting bird clearance survey through the County prior to scheduling any weed abatement/mowing activity. The County shall provide a calendar period when abatement activities may occur. County will also identify areas where abatement work is prohibited, if any. No excavation of the vegetative layer will occur in order to avoid damage to the landfill cover system. Additional soil and, or aggregate will be placed as shown on the design plans, Appendix C. The soil stabilization proposed will either be a low growth plant mix recommended by a horticulturist or aggregate base placed in the array field and access road to serve this purpose. Soil stabilization materials and application methodologies shall be subject to County and Regulatory Agency approval prior to implementation. The design load calculations for the ground-mounted and column supported solar arrays were prepared by Stronghold Engineering and are presented in Appendix C. The loads were used to size the pads under the ground-mounted arrays and to size the column footings. A geotechnical investigation and report was prepared by Geotechnical Professionals Inc. (GPI), February 2014. The recommendation of the report was to keep the ground pressure on the existing landfill soil cover less than a maximum bearing pressure of 750 pounds per square foot(psf). 5 ESTIMATED SETTLEMENT The maximum settlement of the cover in post-closure for self-weight and other general loads was estimated to be up tol6 feet. Approximately 4 feet of settlement has occurred thus far in post- closure. Additional settlement calculations have been prepared in Appendix D (page 192 of this PDF) for the design loads on the ground-mounted and column footings as part of this PCLUP. The maximum area settlement is estimated to be up to 12 feet with a maximum differential settlement of 1-foot over the Post-Closure period. Existing infrastructure may be impacted by 4