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H. Project Description enclosing this facility, allowing for the stormwater to be collected with that from the scale house. The design of the surface water control system for landfill run-off includes stormwater from the temporary hazardous storage facility and the scale house. As previously mentioned,Little Johns Creek would be realigned to the north and west of the existing landfill,to exit the landfill at the same location at which it now exits. The realignment, would increase the length of the creek by 290 feet and include a proportionate reduction in the slope of the channel. After realignment the creek would be lined with a geomembrane liner covered with dirt and riprap. Realigning the creek would eliminate flood plain areas from the horizontal expansion areas; eliminate the primary potential run-on source from the horizontal expansion areas,allow for maximum use of the landfill;eliminate the potential for subsurface water migration into the existing landfill; and eliminate the potential for groundwater and landfill gas into the surface water of Little Johns Creek. The existing and proposed landfill would have a perimeter surface water ditch system to route landfill run-off to the detention facility and intercept any surface water run-on that could be directed towards the expansion phases. In addition,an intermediate perimeter ditch would be provided to collect run-off from the existing landfill and to prevent run-on toward active landfilling areas. Design of the perimeter ditches would provide for capacity of the 100-year, 24- hour storm. Run-off from areas with intermediate closure would be directed to the perimeter surface water ditches,provided that the run-off is not contaminated by leachate. Side slopes would be carefully monitored for leachate seepage. Silt fences would be used as necessary in active and intermediate landfill closure areas to control soil erosion. Once the proposed landfill is closed,surface water would be collected by a network of interception ditches on the slope. Interception ditches would have an appropriate lining based on design velocities. The interception ditches would feed into catch basins connected to the Lq perimeter ditch system. The perimeter ditch system would take the water to the detention facility. Culverts in the catch basins would be designed to include outlet control structures to protect the perimeter ditch lining. This system is designed to handle a 100-year, 24-hour storm. II.15