CCP 01-31-1994 - Laserfiche WebLink

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I ~ pavement thickness ranging from l'h to 3',4-inches and a non-crushed gravel base ranging from 4'% to 6'h-inches in thickness. The subgrade again consists of clayey fill soils underlain by sandy lean clay and clayey sand natural soils. A wet silty sand layer was present above the till at boring #12 presented on Exhibit 4. The alligator cracking and the presence of moisture in the sample collected at boring #12 again indicate the need for subgrade I corrections and drainage improvements along Dunlap Street. The Am soils report is presented in Appendix A. I Keithson Drive Keithson Drive is a street that is approximately 800 feet in length and 10 years in age. The I street is currently constructed to the City's 32-foot wide, 9-ton design standard with sunnountable concrete curb and gutter. The pavement contains limited cracking and no distress that might be associated with soft subgrade conditions or water trapping/frost distress. I The sewer and water utilities installed on Keithson Drive were completed in 1983 and are not in need of repairs or maintenance. I The problems with the pavement surface on Keithson Drive appear to be associated with utility service trench settlement rather than differential frost heaving. Three soil borings were I advanced along the length of Keithson to evaluate the pavement conditions, subgrade conditions and any differences between apparent utility trenches and native subgrade areas. The pavement consists of 2'h to 3-inches of bituminous pavement underlain by 5 to 7'h- . inches of crushed limestone base. A 2 to 2'h-foot granular borrow layer lies beneath the base material, beneath which are sandy lean clay and clayey sand fill soils. The soils were determined to be suitable by Am. Significant pavement problems associated with sub grade I soils should not be an issue in the future as a very limited amount of settlement will occur after the roadway has been in-place for several years. I Boring #2 was intentionally located in a utility trench to attempt to determine possible causes of differential settlement. There were no significant differences in the material at the time of testing, which would indicate that future settlement should not occur, thus reducing the I probability of future pavement deflection. The locations of the soil borings are presented on Exhibit 5. I Storm drainage improvements were implemented with the street construction in the 1980's and these improvements appear to adequately contain and route the storm drainage runoff into Keithson Pond. I PROPOSED IMPROVEMENTS I The various options of street rehabilitation for these four streets have been reviewed and discussed with City staff and the City Council. The roadways are clearly in need of improvements, three methods of which are outlined below: I {' 9 I