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Geotechnical Engineering Report <br /> Proposed Flight Line Steam Line Project lrerracon <br /> ' Boeing Everett Facility• Everett, Washington <br /> January 17, 2012 ■ Terracon Project No.: 81115085 <br /> 4.8 Pavement Restoration Considerations <br /> Subgrade soils, base course, and pavement adjacent to the top edge of the trench is typically <br /> ' loosened or disturbed during excavation. This area should be rebuilt during pavement <br /> restoration, by additional pavement sawcuts and removal/replacement at least 12 inches back <br /> from the trench top edge. Borings B-3 and B-4 encountered fill soils with relatively low fines <br /> contents. These soils may tend to cave, particularly in the presence of perched groundwater <br /> seepage. For preliminary planning purposes, we recommend pavement restoration/replacement <br /> in these areas be considered for a distance back from the trench top edge equal to 12 inches, or <br /> Y2 the thickness of the fill, whichever is greater. In addition, pavement restoration should include <br /> consideration of existing concrete panel joint locations. <br /> Preliminary plans indicate that the new pavement section will consist of 11 inches of concrete over <br /> 4 inches of WSDOT Crushed Surfacing Top Course. We recommend a Modulus of Subgrade <br /> ' Reaction (k) of 250 pci for rigid pavement design provided that the Crushed Surfacing Top <br /> Course and underlying engineered fill are repaired and compacted in accordance with the <br /> recommendation presented in this report. <br /> 5.0 GENERAL COMMENTS <br /> Terracon should be retained to review the final design plans and specifications so comments <br /> can be made regarding interpretation and implementation of our geotechnical recommendations <br /> in the design and specifications. Terracon should also be retained to provide observation and <br /> testing services during earthwork related construction phases of the project. <br /> The analysis and recommendationspresented in this report are based upon the data obtained <br /> Y P P e <br /> ' from the borings performed at the indicated locations and from other information discussed in <br /> this report. This report does not reflect variations that may occur between explorations, across <br /> the site, or due to the modifying effects of construction or weather. The nature and extent of <br /> ' such variations may not become evident until during or after construction. If variations appear, <br /> we should be immediately notified so that further evaluation and supplemental <br /> recommendations can be provided. <br /> ' The scope of services for this project does not include either specifically or by implication any <br /> ' environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or <br /> prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the <br /> potential for such contamination or pollution, other studies should be undertaken. <br /> ' This report has been prepared for the exclusive use of our client for specific application to the <br /> project discussed and has been prepared in accordance with generally accepted geotechnical <br /> 1 <br /> Responsive • Resourceful • Reliable 19 <br />