3620 36TH PL NE 2018-01-02 MF Import

• Construction activities should be scheduled so that the length of time that soils are left exposed to moisture is reduced to the extent practical. 4.2.9 Temporary Slopes We recommend temporary slopes constructed in fill placed to raise site grades and the native organic silt soils be inclined no steeper than 1 V2H:IV. Flatter slopes may be necessary if seepage is present on the face of the cut slopes or if localized sloughing occurs. In addition, vibrations from construction equipment can cause sloughing of temporary slopes and thus slopes may have to be flattened if soughing is observed. For temporary slopes at the site, we recommend that: • No traffic, construction equipment, stockpiles or building supplies be allowed at the top of the cut slopes within a distance of at least 10 feet from the top of the slope. • Exposed soil along the slope be protected from surface erosion using waterproof tarps or visqueen • Construction activities be scheduled so that the length of time the temporary cut is left open is reduced to the extent practical. • Erosion control measures be implemented as appropriate such that runoff from the site is reduced to the extent practical • Surface water is diverted away from the excavation. • The general condition of the slopes be observed periodically by a geotechnical engineer to confirm adequate stability. Since the contractor has control of the construction operations, the contractor should be made responsible for the stability of cut slopes, as well as the safety of the excavations. All shoring and temporary slopes must conform to applicable local, state and federal safety regulations. 4.2.10 Permanent Slopes We recommend that permanent cut and fill slopes be constructed no steeper than 2H:1V. To achieve uniform compaction, we recommend that fill slopes be overbuilt by about 2 feet and subsequently cut back to expose properly compacted fill. To minimize erosion, newly constructed slopes should be planted or hydroseeded shortly after completion of grading. Until the vegetation is established, some sloughing and raveling of the slopes shou!d be expected. This may require localized repairs and reseeding. Temporary covering, such as clear heavy plastic sheeting, jute fabric, loose straw or rolled erosion control mats should be used to protect the slopes during periods of rainfall. 4.3 PRELOAD FILL 4.3.1 Preload Height The purpose of placing a preload fill is to pre -induce a major portion of the settlement that would otherwise occur when site fill and structure loads are applied. We recommend that each settlement sensitive structure area be preloaded to the minimum height shown in Table 1. iT G e 0 E n g i n e e r s 14 He No. 10625-001-02/123003