1919 112TH ST SW 2016-01-01 MF Import

vLfarch 2� 1994 ]3 943-1525 under conttol to a positive and permanent discharge system such as the storm sewer. We do not expect that aign�cant quantities of groundwater will be encountered in site excavations, however, it can be controlled using ditches, sumps, and pumps. 4.4.3 Euthworks The native till soil on site is compact to very dense and locally can be difficult to excavate. ln places it may require ripping. In addition, occasional cobbles or boulders may be encountered. The native, non-organic, site soils can be used as site fill provided they can be compacted near the optimum moisture con:ent as determfned by ASTM D-1557. The till is considered a moisture aensitive soil, due to the high silt content. DistUrbed till will rapidly degrade in wet weather conditions rendering adequate compaction impossible. Accordingly we recommend that the major earthworks be completed during the dry weather season. Winter construction may require the import of structural fill and the export and offsite disposal of unsuitable onsite soils. In addition, the use of geotextiles and/or rock may be required during the wet, winter season to stabilize sofr subgredes. Additional erosion control measures may be required during the wet weather season. The protection of exposed suhgrades is the responsibility oE the contractor. Efforta should be made to profect subgrades from damage in wet weather conditions. Subgrades disturbed as a result of wet weathrr should t repaired at the contractors expense. Excavation aafety is the responsihility of the contractor. All applicable OSHA safety standards for cut slopes, trenches and excavations should be followed. Temporary construction cuts greater than 4 feet in height should be no steeper than 1H:1V (Horizontal to Vertical). This slope recommendation assumes a dry cut slope. All atructutal fill placed within 2 feet of structures or pavements should be compacted to a minimum of 95 percent of ASTM D-1557. All other structural fill should be compacted to a minimum of 90 percent of ASTM D-]557. StruMural fll shall be e free draining sand and gravel soil, free from organics, and contain less than 5 percent by weight passing the #200 afeve. flasement walls should contain a footing drain as described in Section 4.4.3. We recornmend that the footing drain be covered with e minimum of three feet of drainage gravel. The backfill behind the wall should consist of free dreining send and gravel with lese than 5 percent by weight passing the #2U0 sieve size. Altematively, the wall can be covered with a geotextile drainage blanket such as Miradrain 6000 or equivalent, and backfilled with properly moisture conditioned onsite soils. The drainage blanket should provide a positive water (low connection to the gravel wrapped drain pipe. All existing above- and below-grade structures should be removed and properly disposed o(. This includes the existing house, sheds, pavements, septic tank, and tash pile located at the northeast corner of the site. Excavations created to remove such structure, should be backfilled with compacted fill to achieve permanent site grades. Golder Aesoclates