Finalized Contract Agreement Packet

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June 13,2023 HWA Project No. 2022-188-2 I For the buried portions of the retaining walls, an allowable passive pressure equal to an equivalent fluid pressure of 360 pounds per cubic foot may be considered. Passive seismic earth pressure equal to that generated by a fluid with a unit weight of 250 pounds per cubic foot may be used in design. The upper 2 feetof passive pressure should be ignored. A factor of safety of 1.5 should be applied to the passive static earth pressure and a factor of 1.1 should be applied to the passive-seismic earth pressure. Traffic surcharges should also be included in the wall design, as appropriate. We recommend that the surcharge pressure from vehicular loading be assumed to be equivalent to an additional uniform lateral pressure over the entire back of the wall equal to 108 pounds per square foot for a non-yielding wall and 68 for a yielding wall. This is based on a vehicular load of 250 psf acting on the slab behind the wall. This traffic load does not account for temporary construction surcharge loading that may exist above the wall during the course of construction, which should addressed by the contractor during construction. 4.7.3 Wall Drainage A minimum 4-inch diameter, perforated, rigid plastic drain pipe should be placed on the up-slope side at the bottom of retaining walls and be discharged into the local storm drain system or other suitable outlet. These wall drains should not be connected to the perimeter footing drains in a manner that would allow water to run from the perimeter drains down into the wall drain. Wall and foundation drains and roof downspouts should not be tightlined into the same pipe. 4.8 PnnivrnnrNT FILL Sr,opns Permanent fiIl slopes are planned for the perimeter areas sulrounding the transfer station. All permanent fills should be no steeper than2H1V. Consideration may be given to providing a five-foot wide restricted-entry catchment zone along the base of all permanent fills 10 feet or higher. Movable concrete barriers can be positioned along the outside edge of this zone to prevent any material that may ravel off the slope from entering an area where it may encounter vehicles, County personnel and the public. All permanent fill slopes should be protected from erosion as prescribed in Section 4.12,6. 4.9 Covnosr ARna (Nonrnwosr AREA) The compost Area is situated in the northwest portion of the site and will consist of a paved working area roughly 5.07 acres in size that will accommodate grinding, mixing, curing and storing of composted organic and soil materials. It is anticipated that heavy equipment such as trommel screens, windrow turners, grinders andtractorlloaders will traverse the pad. Periodic transfers of material in and out by large tractor trailer haulers are also anticipated. Results of the soil boring explorations we conducted and review of the pre-existing exploration logs in this area indicate that the proposed compost pad area footprint is underlain by 4 to 8 feet of topsoil and 2022-188-21 KCTS - Final Geotechnical Report l3 HWA GEOSCIENCES INC.