13-10-009

Division 13-10-009
Structural Section

Sections:

A. For all new public and private streets, a structural section shall be designed by a registered professional engineer licensed in Arizona specializing in geotechnical engineering. A structural section design shall be performed based upon an adequate number of soil samples. The minimum number of samples shall be one (1) every five hundred (500) feet, or as determined by the engineer. The pavement shall be designed for a twenty (20) year life and meet the requirements of the Western Technologies, Inc., 1983 report (or most current revision): "Asphalt Concrete Pavement Design for the City of Flagstaff." The final street construction shown on the construction plans shall meet the recommendations of the design or the minimal structural section requirements of Detail 10-09-010, whichever is greater.

B. Overall street sections are shown in the Standard Drawings. Other design considerations shall be based on the following standards:

1. On projects where the contractor causes excessive damage to an existing paved street or there are multiple street cuts (maximum of four (4) in five hundred (500) feet), an asphalt overlay shall be required.

2. Except on super-elevated curves and at intersections, all new street sections will have a crown to provide drainage from the centerline to each gutter. The slope provided by the crown shall not be more than two percent (2%) or less than one percent (1%) as measured from centerline to edge of pavement.

3. Finish slope resulting from excavation or embankment shall not exceed 2:1 unless approved by the City Engineer upon receipt of a sealed certificate in writing by the engineer via a soils report that the steeper slope, as constructed, will be stable.

4. All publicly and privately constructed cut and fill slopes shall be adequately protected to prevent erosion. Cut and fill slopes greater than two (2) horizontal to one (1) vertical shall not be permitted unless the slope is determined to be stable as demonstrated by a quantitative geotechnical analysis prepared by a registered geologist or other qualified registrant. Slopes of two (2) horizontal to one (1) vertical exceeding six (6) feet in height shall use rigid or semi-rigid erosion protection products including, when appropriate, reseeding pursuant to Chapter 13-17, Erosion Control. All slopes of three (3) horizontal to one (1) vertical slopes or greater, including two (2) horizontal to one (1) vertical slopes of less than six (6) feet in height, shall be reseeded pursuant to Chapter 13-17, Erosion Control. To provide retention of the required seeding, the City Engineer may require the use of filter fabrics to prevent erosion of the seeding and/or mulch prior to the establishment of vegetation growth.

5. A chip seal fee is required for all new public pavement improvements including streets, turn lanes, pavement matchups, trench repairs, and all other cases where a new asphalt surface course is constructed. The fee shall be payable to the City of Flagstaff and shall be calculated as defined in Section 3-10-001-0002. The fee shall be paid at the time of the applicable construction permit. (Ord. 2017-22, Rep&ReEn, 07/05/2017)

13-10-009-0001 Structural Section