11632 EVERGREEN WAY BASE FILE 2018-01-01 MF Import

Proposed Retail Dcvelopment J-1443 1121h Street and Hwy.99 February 26,2004 ( Everett,Weshington Page 20 Department of Transportation, Standard Specifications for Rocds, Bridges, and Municipal Construction. Wc recommend that the crushed aggtegate top course and pit-run subb�se r.iaterial conform to Sections 9-03.9(3) and 9-03.14(1), respcctivcly. It is our opinion that the on-site glacial till soils azc not suitable for subbase applicarions. In licu of crushed gravel top course, asphalt-treated base (ATB) can be substituted. The ATB would provide a more durable wearing surface if the pavement subgrade azeas will be exposed to consWction traffic prior to final paving with Class B asphalt. The following table presents recommended pavement sections for anticipated standard- and heavy-duty traffic levels, based on our calcwations and ihe minimums in the Geotechnical L:vestigation 5pecifications and RepoK Requirements. Recommended As halt Pavement Sections for 20-Year Lifes an Pit-Run ATB Substitute for Tra(xic Asphalt Crushed Top/Base Subbase Crushed Top Thiclmcss in. Course in. "Inches Course nc6es " Heaw, 167,900 ESALs 4 4 6 3 � Standard 73,000 ESALs 3 4 5 3 *ATB: Asphalt Trcated Dase may be substituted for crushed Top Course beneath Class B asphalt. Glacial till is not swtable for subbasc applications. If thc compaction standatd is reduced to 90 percent of the modified Proctor maximum dry density, wc recommcnd ihat the subbase thickness be increas:d by 4 inches for both standard and heavy-duly sections. I'avcment design recommendations assume proper drainage and construction monitoring and are based on AASHTO Design parametecs for a 20-year design period. However, continual . flexible maintenance along �vith major rehabilitation after about 8 to 10 years should be cxpected to obtain a 20-ycar service life. If possible, construction traffic should be limited lo unpavcd and untreated roadways, or specially consttucted haui roads. If this is not possible, the pavement design should include an allowance for conslruction traffia ' 5tabilizing thc subgrade with a faUric such as Amoco 2006 or Mirafi 600X,or equivalent, may bc necessary during wet wcather construction or wet subgrade cottditions. Proper geotextile fabrics will maintain segrcgation of the �ubgrade soil and base coutse materials. If the subgrade soils are allowed to migrate upwazd into the base course, the result would be decreased pavement support. Thc usc of stabilizaHon fabric will not reduce the necessary base rock thickness, as J-1443,022C04 � :�..4) "