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r� GEQMATRIX Lateral loads imposed on the pump station by an earthquake or wind will be resisted by the passive resistance of the adjacent soil acting on the sides of the footings and by sliding rr frictional forces. The passive soil resistance having an equivalent fluid pressure of 300 psf is recommended for seismic design for the types of materials that will be used as backfill for the ,.,. pump station structure footings. A coefficient of sliding resistance of�t =0.35 should be used when a footing is poured neat on a building pad of granular material that is placed on the native I� soil surfaces. This value assumes no factor of safety (i.e., a factor of safety equal to 1.0). ` Total and differential settlements of the new pump station should be negligible if the recommendations presented in this report are followed. 5.4 SLABS ON GRADE Slabs for equipment or minor surface structures/facilities should be placed on a 6-inch-thick La pad of compacted aggregate base material or crushed rock as described in Section 5.2.4, Building Pad. 1f damp-proofing of the slab-on-grade-floor of the pump station is desired, the slab should be • placed on 6 inches of crushed rock. The crushed rock should be covered with a waterproofing membrane followed by 2 inches of protective sand that is moistened and leveled before concrete is poured. 5.5 SEISMIC DESIGN CONSIDERATIONS As discussed in Section 4.0, the pump station site is close to potentially active seismic sources. Consequently, the site probably will experience strong earthquake ground shaking during its useful life. Based on the Uniform Building Code (UBC, 1997), the site is located in Zone 4, and subsurface conditions are consistent with those designated in SD in the code. According to maps prepared by the California Division of Mines and Geology (CDMG, 19998),the site is +- located more than 15 kilometers from the Greenvile fault, which is a Seismic Source Type B. 6.0 PAVEMENT DESIGN AND CONSTRUCTION New asphalitc concrete pavements will be constructed around the Lewis Manor Wall Pump ,M Station. One driveway is planned for construction along West 12th Street. We understand that traffic at the site will be light- Pickup trucks used by maintenance crews will occasionally V access the site; light weight cranes may be used to remove the well pump and other mechanical equipment. I:1Project15000s1531311.E W IS-MAN.DOC 11