500 LAUREL DR 2016-01-01 MF Import

Geotechnical Eng:neering Study Page 15 00-2267 Three Story Addition - 500 Laurel Strt.et, Everett January 31, 2001 dump truck, though the somewhat restricted spacs at this site is likely to eliminate this as an option. Proofrolling involves the roller (or loaded dump tn�ck) making one pass over the subgrade to determine if the subgrade �:umps or �veaves or exhibits any visible in�+.ability. One pass is considered to be a single passage of the roller or loaded dump truck in each direction, forwards and backwards, over the same strip of subgrade. The purpose of the proofrolling is to determine the presence and define the approximate areal extent of any soft or unstable areas. Soil in any soft or unstable areas should be moisture conditioned, as appropriate, and recompacted. If after recompaction these areas remain soft or unstable, they should be overexcavated and the unsuitable materials removed and replaced with compacted structural fill, or a crushed rock, to a depth that provides a stable base. Typically, a depth of two to three feet is adequate for this purpose. Redensification: In our professional opinion, because of the relatively loose cor.dition of the shallow su�cial soils, redensification of the bearing soils will be required in the general building pad area. Redensification may be achieved by having the comp��ction equipmeni make a minimum of four and a maximum of six passes. (As described above, one pass is a passage ofthe roller in each direction, forwards and backwards, over the same strip of subgrade.) On this site, this redensification process showd be camed out overthe whole of the additions excavated subgrade area. If conducted undercontrol this process should help enhance the degree of in-situ density within the upper approximately two to three feet of underlying soil. Structural Fill: Although we do not anticipate a need for any structural fill on this project, should it become necessary a structural fill is �efined as any fill placed under buildings, driveways, slabs, or any other load-bearing areas. Ideally, but particularly for wet weather construction, structural filis should consist of a free- draini�zg granular material with � maximum size flf three inches. The material should have about 75% passing the number 4 mesh sieve and no more than 5 percent fines (silt and clay sized materia! passing the No. 200 mesh sieve). During U