Two way traffic must be maintained at all times unless special arrangements have been made with the Pima County Department of Transportation. Trenching operations crossing a traveled roadway must be segmented as shown on Detail Supplement, pages 18 and 19, to maintain two way traffic.
Trenching or open trench parallel to a roadway shall not exceed the distance from the edge of one crossing street to the edge of the next crossing street, or a length no greater than 300 lineal feet maximum.
Trench material (bedding, shading, backfill) shall be divided into two classes: Class I is required for any excavation within the effective roadway prism. Class II material shall be permitted outside the effective roadway prism.
Backfilling shall be divided into two classes, Class I and Class II. Class I is required for any excavation within the effective roadway prism. Class II backfilling shall be permitted outside the effective roadway prism.
For the purpose of this Article, the effective roadway prism for a fully developed section shall be defined as the area used as the
traveled road, the area under the curbs, the area from back of curb to outside edge of sidewalk, and an area one-half the depth of the trench from the outside edge of the sidewalk. If the roadway consists of strip paving and shoulders, the effective roadway prism shall consist of the area used as the traveled road, the roadway shoulders, and the area one-half the depth of the trench from the outside edge of the shoulder.
Class I bedding, shading, and backfill conforming to the requirements of the Standard Specifications shall be placed in lifts not exceeding eight (8) inch lifts of premoistened material and mechanically compacted to a minimum 95% of the testing laboratory maximum density (Section 501).
Class II material can be any material not containing trash, or organic material. Trench material may be placed in eighteen inch lifts and, if the material is granular in nature, it may be compacted by water settling with a jetting probe if approved by the Engineer. Flooding shall not be permitted.
Class II material in the road right-of-way but outside the road prism shall be compacted to a minimum 90% of the laboratory maximum density. In public easements not subject to vehicular traffic the compaction shall be a minimum of 85% of the maximum laboratory density.
Trench material compaction tests will be performed in accordance with ADOT 225-227, 230, and 232, a minimum of every third lift, at least one every 500 feet.
The Pima County Department of Transportation Inspector may also order load tests to be performed to determine the suitability of
the backfill before paving. Such tests are to be performed with a vehicle of approximately eighteen thousand-pound axle loads. Excessive movement or settlement of backfill shall be cause for rejection of the work.
In the event the contractor elects not to make the permanent pavement repair immediately after backfilling and compaction, he shall provide a temporary one-inch thick cold-mix asphalt patch over the area or areas which will ultimately receive a permanent patch. He will also be responsible to assure the temporary patch is maintained at all times. A permanent patch shall be placed within fifteen (15) calendar days of the initial work or sooner if requested, in writing, to do so by the County Engineer or his representative.
PAVEMENT REPLACEMENT STANDARD DETAILS:
Whenever existing pavement is cut and removed it shall be replaced in accordance with a Type 1, Type 2, or a Type 3 patch, as per the Standard Details for Public Improvements, Standard Detail No. 216
It will be mandatory to use a Type 3 pavement replacement on any existing concrete roadway, when the trench width is no more than 4'-0".
A Type 1 pavement replacement patch will be required on any roadway, which is not concrete, within Pima County when the trench width is no more than 4'-0".
A Type 2 pavement replacement patch will be required when the trench widths exceed 4'-0".
If a pavement cut is made in the roadway, parallel to the centerline, within either traffic lane, that lane shall require a full lane pavement replacement and a single chip and seal application on the full width of the roadway.
If a pavement cut is made in the roadway, parallel to the centerline, which is within the center of the roadway, or disturbs both lanes, pavement replacement shall be the full width of the roadway. If only the edge of the roadway is disturbed, a pavement patch is required per the Standard and that one lane shall require a single chip and seal application.
For excavations made in the roadway shoulder, the surface materials will be replaced with aggregate base course. For all other excavations inside the right-of-way, but outside the roadway prism, the surface material will be replaced with material of equal quality.
Permanent pavement replacement may be performed by the contractor, provide the pavement materials from an approved materials plant, and work is performed per the Standard Construction Methods and Specifications.
The work site shall be maintained in a neat and acceptable condition. Care shall be taken to prevent spillage on streets and roadways over which hauling is done, and any such spillage shall be cleaned up immediately. All waste materials shall be removed and the general condition of the site shall be as good or better than before construction. Final approval of the cleanup shall be given by the Department of Transportation Inspector.
EXCAVATION IN AN UNPAVED ROADWAY:
Excavation in an unpaved roadway where the wearing surface is native material shall be regulated to minimize particulate air pollution from becoming airborne as fugitive dust. Unpaved roadways, where excavation or grading has taken place, shall be restored to their original condition. If the roadway surface has been treated with a dust palliative, the restored surface shall be treated with a palliative of equal suppressing capacity.
In no case, shall the trench backfill be water settled. The minimum allowable surface treatment for unpaved roads shall be to add water until the surface soil layer is at optimum moisture and fairly well compacted.