1600 MADISON ST 2016-01-01 MF Import

Mc Chris Lark February 20, 2001 6.0 CONSTRUCT[ON CONSIDERATIONS 6.1 SITE PREPAI4:TIUN AND REMEDIAL GRADING After demolition of the existing buildings, the site prepazation should begin with removal of debris, vegetation, topsoil, and deleterious matter from the azea of the proposed improvements. Undesirable material not suitable for landscaping should be exported &om ihe site. Following remova: of deleterious material and rough grading, the subgrade exposed beneath the building and pavements should be compacted to a dense and unyielding condition and then proof-rolled with a fully-loaded dump truck or a lazge, self-pmpelled vibratory roller. In azeas where very dense glacial till is exposed, proof rolling will not be required. We recommend that the proof rolling be observed by our geotechnical engineer to identify any soft, yielding azeas that may need to be over-excavated and replaced with shucturai fill. The structural fill should be placed in accordance with the compaction criteria presented in Section 6_2, below. Areas of existing (to be demolished) or former USTs may require local over excavation and backfilling to create a subgrade suitable for tne suppoR of the building. Areas that may require such additional work include the former (gas) UST located on the west side of the existing building and the existing (diesel) UST on the north side of the building (See Figure 2). 1'he diesel UST should be removed and replaced with a compacted backfill before the new fire station is constructed. 6.2 STRUCTURAL FILL AND COMPACTION Structural fill should consist of clean, free-draining granulaz soils that aze relatively free from oTganic matter or other deleterious materials. The on-site soils contain a significant amount of fines and may be suitable for use as structural fill during dry weather conditions only. Imported swctural fill should contain materials no larger than 4 inches and the material should also contain less than 7 percent fines (portion passing the U. S. Standazd No. 200 sieve). Materials meeting this requirement include Gravel Sotrow as specified in Section 9-03.14(1) of the 2600 WSDOT Standard Specifications for Road, Bridge, and Muxicipal Constnretion (WSDOT, 2000). The fine-grained portion of structural fill soils should be non-plastic. A fines content greater than 7 percent, however, may be acceptable if the earthwork is performed during relatively dry weather and the contractor's methods are conducive to proper compaction of the soil. The use of materia! with a fines content greater than 7 percent sheuld be approved by the geotechnical engineer prior to use. i� i � � � � �p i t� : n :� ;� ;f ;'s � � 00-046- l00 Geotech Repod 6 PanGEO, Inc. �` ,,.