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HomeMy WebLinkAboutTrench Restoration and Street Overlay notes.docxCITY OF RENTON STANDARDS All materials and workmanship shall be in accordance with the City of Renton Standard and Supplemental Specifications (current adopted version) except where otherwise noted in these standards. Materials and workmanship are required to be in conformance with standards for the Standard Specifications for Road, Bridge, and Municipal Construction prepared by the Washington State Chapter of the American Public Works Association (APWA) and the Washington State Department of Transportation (WSDOT) and shall comply with the current edition, as modified by the City of Renton Supplemental Specifications. An asphalt paver shall be used in accordance with Section 5-04.3(3) of Standard Specifications. A “Layton Box” or equal may be used in place of the power-propelled paver. Rollers shall be used in accordance with Section 5- 04.3(4) of the Standard Specifications. “Plate Compactors” and “Jumping Jacks” shall not be used in lieu of rollers. Trench backfill and resurfacing shall be as shown in the City of Renton Standard Details, unless modified by the City permit. Surfacing depths shown in the standard details are minimums and may be increased by the Engineer to meet traffic loads or site conditions. Requirement for Patching, Overlay, and Overlay Widths: All trench and pavement cuts shall be made by sawcut or by grinding. Sawcuts or grinding shall be a minimum of one foot (1') outside the trench width. The top two inches (2") of asphalt shall be ground down to a minimum distance of one foot (1') beyond the actual outside edges of the trench and shall be replaced with two inches (2") of Class B asphalt, per City of Renton Standard Plans. At the discretion of the engineer, a full street width overlay may be required. Lane-width or a full street-width overlay will be determined based upon the location and length of the proposed trench within the roadway cross-section. Changes in field conditions may warrant implementation of additional overlay requirements. Trenches (Road Crossings): The minimum width of a transverse patch (road crossing) shall be six and one-half feet (6.5'). See City of Renton Standard Plans. Any affected lane will be ground down two inches (2") and paved for the entire width of the lane. The patch shall be a minimum of one foot (1') beyond the excavation and patch length shall be a minimum of an entire traveled lane. If the outside of the trenching is within three feet (3') of any adjacent lane line, the entire adjacent traveled lane affected will be repaved. An area including the trench and one foot (1') on each side of the trench but not less than six and one- half feet (6.5') total for the entire width of the affected traveled lanes will be ground down to a depth of two inches (2"). A two-inch (2") overlay of Class B asphalt will be applied per City standards. Trenches Running Parallel with the Street: The minimum width of a longitudinal patch shall be four and one-half feet (4.5'). See City of Renton Standard Plans. If the trenching is within a single traveled lane, an entire lane-width overlay will be required. If the outside of the trenching is within three feet (3') of any adjacent lane line, the entire adjacent traveled land affected will be overlaid. If the trenching is greater than or equal to 30% of lane per block (660 foot maximum block length), or if the total patches exceed 12 per block, then the lanes affected will be overlaid. Minimum overlay shall include all patches within the block section. The entire traveled lane width for the length of the trench and an additional ten feet (10ʹ) at each end of the trench will be ground down to a depth of two inches (2ʹʹ). A two-inch (2ʹʹ) overlay of Class B will be applied per City standards. Potholing: Potholing shall meet the same requirements as trenching and pavement restoration. Potholing shall be a minimum of one foot (1') beyond the excavation. All affected lanes will be ground down to a depth of two inches (2") and paved not less than six and one half feet (6.5') wide for the entire width of the lane. Potholes greater than five feet (5') in length, width or diameter shall be restored to trench restoration standards. In all cases potholes shall be repaired per Renton Standard Plans. Restoration requirements utilizing vactor equipment will be determined by the Engineer. Pavement Removal in Lieu of Grinding: The contractor in all cases can remove the pavement in the replacement area instead of grinding out the specified two inches (2") of asphalt. Full pavement replacement to meet or exceed the existing pavement depth will be required for the area of pavement removal. Patching of pervious concrete shall follow American Concrete Institute (ACI) 522.1-13. Porous asphalt shall be specified on a project-by-project basis by the engineer. Permeable materials should be replaced in-kind where feasible. Patching porous asphalt with conventional asphalt is acceptable if it is no more than ten percent (10%) of the total facility area or does not impact the overall facility function. Appropriate precautions shall be taken during pavement repair and replacement efforts to prevent clogging of adjacent surfaces. Trench Backfill and Restoration Construction Requirements: Trench restoration shall be either by a patch or overlay method, as required and indicated on City of Renton Standard Plans. All trench and pavement cuts, which will not be overlaid, shall be made by sawcut or grinding. Sawcuts shall be a minimum of two feet (2') outside the excavated trench width. All trenching within the top four feet (4') shall be backfilled with crushed surfacing materials conforming to Section 4-04 of the Standard Specifications. Any trenching over four feet (4') in depth may use materials approved by the Engineer or Materials Lab for backfilling below the four-foot (4') depth. If the existing material (or other material) is determined by the Engineer to be suitable for backfill, the contractor may use the native material except that the top six inches (6") shall be crushed surfacing top course material. The trench shall be compacted to a minimum ninety-five percent (95%) density, as described in Section 2- 03 of the Standard Specifications. In the top six feet (6') of any trench, backfill compaction shall be performed in eight (8) to twelve-inch (12") lifts. Any trench deeper than six feet (6') may be compacted in twenty-four inch (24") lifts, up to the top six-foot (6') zone. All trench backfill shall be firm and unyielding but in no case shall be compacted to more than ninety-two percent (92%) of maximum density in permeable pavement areas. All compaction shall be performed by mechanical methods. The compaction tests may be performed in four-foot (4') vertical increments maximum. The test results shall be given to the Engineer for review and approval prior to paving. The number and location of tests required shall be determined by the Engineer. Temporary restoration of trenches for overnight use shall be accomplished by using MC mix (cold mix), Asphalt Treated Base (ATB), or steel plates, as approved by the Engineer. ATB used for temporary restoration may be dumped directly into the trench, bladed out and rolled. After rolling, the trench must be filled flush with asphalt to provide a smooth riding surface. If the temporary trench restoration does not hold up, the contractor shall repair the patch within eight hours of being notified of the problem by the City. This requirement applies 24 hours per day, seven days per week. In the event that the City determines to repair the temporary patch, the contractor shall reimburse the City in an amount that is double the City’s costs in repairing the patch, with the second half of the reimbursement to represent City overhead and hidden costs. Asphalt Concrete Class E or Class B shall be placed to the compacted depth as required and indicated on City of Renton Standard Plans or as directed by the Engineer. The grade of asphalt shall be AR-4000W. The materials shall be made in conformance with Section 9-02.1(4) of the Standard Specifications. Tack coat shall be applied to the existing pavement at edge of saw cuts and shall be emulsified asphalt grade CSS-1, as specified in Section 9-02.1(6) of the Standard Specifications. Tack shall be applied as specified in Section 5-04 of the Standard Specifications. Asphalt Concrete Class E or Class B shall be placed in accordance with Section 5-04 of the Standard Specifications; except those longitudinal joints between successive layers of asphalt concrete shall be displaced laterally a minimum of twelve inches (12"), unless otherwise approved by the Engineer. Fine and coarse aggregate shall be in accordance with Section 9-03.8 of the Standard Specifications. All street surfaces, walks or driveways within the street trenching areas shall be feathered and shimmed to an extent that provides a smooth-riding connection and expeditious drainage flow for the newly paved surface. Feathering and shimming shall not decrease the minimum vertical curb depth below four inches (4") for storm water flow. The Engineer may require additional grinding to increase the curb depth available for storm water flow in areas that are inadequate. Shimming and feathering as required by the Engineer shall be accomplished by raking out the oversized aggregates from the Class B mix as appropriate. Surface smoothness shall be per Section 5-04.3(13) of the Standard Specifications. The paving shall be corrected by removal and repaving of the trench only. Asphalt patch depths will vary based upon the streets being trenched. The actual depths of asphalt and the work to be performed shall be as required and indicated on City of Renton Standard Plans. Compaction of all lifts of asphalt shall be a minimum ninety-two percent (92%) of density as determined by WSDOT Test Method 705. The number of tests required shall be determined by the Engineer. Testing shall be performed by an independent testing lab with the results being supplied to the Engineer. Testing is not intended to relieve the contractor from any liability for the trench restoration. It is intended to show the inspector, and the City, that the restoration meets these specifications. All joints, except those associated with permeable pavement, shall be sealed using paving asphalt AR- 4000W. When trenching within the unpaved roadway shoulder(s), the shoulder shall be restored to its original condition, or better. The final patch shall be completed as soon as possible and shall not exceed fifteen (15) working days after first opening the trench. This time frame may be adjusted if delays are due to inclement paving weather or other adverse conditions that may exist. However, delaying of final patch or overlay work is subject to the Engineer’s approval. The Engineer may deem it necessary to complete the work within the fifteen (15) working day time frame and not allow any time extension. Should this occur, the contractor shall perform the necessary work, as directed by the Engineer. A City of Renton Temporary Traffic Control Plan (from Renton Transportation Engineering) shall be submitted and approved by the Engineer a minimum of three (3) working days prior to commencement of work. Removal of Utility Locate Markings from Sidewalks Required: The permittee will be required to remove utility locate marks on sidewalks only within the Center Downtown Zone. The permittee shall remove the utility locate marks within 14 days of job completion.