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June 13,2023 <br />HWA Project No. 2022-188-21 <br />should be excavated a minimum of 22 inches below the proposed top of pavement subgrade to <br />accommodate the proposed pavement section, as discussed in Section 4.1 1.3. The subgrade <br />should then be proof rolled using a with a heavyweight smooth drum roller (on static mode) <br />under the observation ofthe geotechnical engineer. Any subgrade areas that appear to be <br />unstable or incapable of supporting construction equipment or traffic should be stabilized as <br />described below. <br />We recommend that after subgtade proof rolling is conducted as described above, unstable areas <br />ofthe subgrade be sub-excavated at least 12-inches (ifnecessary depending upon finish grade) <br />then covered with a woven geotextile fabric consisting of Tensar HP 570 or equivalent, followed <br />by a layer of Tensar Triax 160 geogrid prior to placement of l2-inches of compacted CSBC. <br />All other pavement subgrade areas should be covered with a woven geotextile fabric, such as <br />Tensar HP 570, or equivalent, prior to placement of structural fill and pavement layers. <br />Material used to raise site grades, or placed directly under pavement structure is classified as <br />structural fill. Imported structural fill should consist of either Crushed Surfacing Base Coarse or <br />Select Borrow depending on application as specified herein and meeting the requirements of <br />WSDOT Standard Specifications Section 9-03.9(3) and 9-03.14(2), respectively. <br />4.11.2 Design Traffic Volume <br />Traffic information, provided by SCS, Inc., indicated that the site could be divided into 4 discrete <br />zones that support varying traffrc loads (K. Shah, electronic communication,2023) as described <br />below. <br />Southwest Area: This area includes the tire recycling area and consists of a paved rectangular <br />area situated just of the compost area. The area serves as a laydown and loading area for tires. <br />The pavement will support pickups, pickup with trailers, and occasional heavyrveight 40 cyd <br />trailers. Based on the traffrc data provided we estimate a total design ESAL's factor of 2,337 for <br />this area as presented in Table 2. <br />Southeast Area: The southeast area encompasses the recycle area which consists of a broad <br />paved area where a series of containers are arranged within a median to accept paper, glass, <br />metal and other recyclable materials. The area also includes access and parking for the MRW <br />and administration buildings. The pavement will support pickups and passenger vehicles, and <br />occasional heavyweight roll-on/roll-off trucks and 24-fooL long 3-axle trucks. Based on the <br />traffrc data provided we estimate a total design ESAL's factor of 275,000 for this atea as <br />presented inTable2. <br />Northeast Area: The paved area includes the scale and transfer station facilities situated in the <br />northeastern portion of the site. All vehicles carrying loads that require a tipping fee will need to <br />2022-188-21KCTS - Final Geotechnical Report I6 HWA GEOSCIENCES INC.