CITY OF WILSON. Public Services Engineering. Backfilling, Compaction, & Patching Policy on Existing Pavements

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1 CITY OF WILSON Public Services Engineering Backfilling, Compaction, & Patching Policy on Existing Pavements

2 INTRODUCTION The City of Wilson recognizes that proper backfilling, compaction, and patching of excavations within the pavement on city streets is necessary to maintain the integrity of the pavement, ensure the life expectancy of the street before resurfacing, and provide a smooth and safe ride for the traveling public. Any cut made in the pavement shall be carefully analyzed prior to performing the work to verify it is the proper size, location and time of the year. By following these policies, resources (personnel and money) shall be used in the most efficient manner. The following guidelines apply to all city departments, as well as, private companies with approved encroachments opening excavations on city maintained streets. Any deviations from these policies must be approved, before any work is done, by the City Engineer. There must be compelling reasons or unusual circumstances for any exceptions. Any city department planning to open cut the pavement on a city maintained street shall notify the Streets Division in advance of doing the work. DEFINITIONS: Backfilling The replacement of earth or the placement of other material into a trench or excavation around and against utility lines (water, sewer, storm sewer, gas, electric, phone cable TV, or fiber). Compaction The process of increasing the density of backfill material in order to increase the strength of the backfill, making it more stable for patching to allow vehicles to pass over the excavation without sinking. Hand and/or mechanical tamps shall be used to achieve the desired compaction. Haunching The process of backfilling up to the spring line of any pipe with a handheld tamp to prevent the pipe from deflecting from side to side during and after construction. Patching - The permanent replacement of asphalt removed during the opening of an excavation in the pavement for any reason. This permanent patch shall be made with hot mix asphalt (S 9.5). Pavement box On streets with curb and gutter: The area under the street pavement and curb & gutter. On streets with no curb and gutter: The area under the pavement. 1

3 A. BACKFILLING ( See detail C01.03 in City of Wilson Manual of Specifications, Standards, and Design) 1. Taps (including water, sewer, and gas) Materials: Within the pavement box (see definitions), gravel screenings shall be used for the entire depth of the excavation. Outside the pavement box but within the R/W, suitable material shall be used for the entire depth of the excavation. Backfill shall be placed in layers, not to exceed twelve (12) inches and compacted to the required densities in Section B Materials not allowed for backfill include: wet materials, frozen materials, construction materials, or organic materials. If tap is punched (dry bored) under curb, no screenings are needed except for the portion that is open cut in the pavement 2. Trenches (including water, sewer, storm sewer, gas, electric, fiber, telephone, cable TV) Materials: Within the pavement box, gravel screenings shall be used for the top three (3) feet of backfill. Select backfill shall be used for any part of the excavation deeper than three (3) feet. Outside the pavement box, but within the R/W, suitable material shall be used for the entire depth of the excavation. Backfill shall be placed in layers, not to exceed twelve (12) inches and compacted to the required densities in Section B. Materials not allowed for backfill include: wet materials, frozen materials, construction materials, or organic materials. 2

4 3. Emergency Repairs For waterline or sewer line breaks resulting in the saturation of the soil from water, the following procedure will be followed: Once the repair is made, all wet material shall be removed from the trench and replaced with clean dry material as outlined in Section A and compacted as outlined in Section B. In no case shall any excavated wet material be put back into the trench. If weather conditions are unfavorable (heavy rains, damaging winds, bitter cold) or work is being done at night, trench may be temporarily backfilled to get the trench to a safe condition for traffic. As soon as conditions improve, the trench shall be re-excavated, backfilled as outlined in Section A, and properly compacted as outlined in Section B. 4. Potholing Any excavation opened for the purpose of locating existing underground utilities prior to installation of other utilities (gas, fiber, etc.) shall be backfilled properly. Materials: Within the pavement box (see definitions), gravel screenings shall be used for the entire depth of the excavation Backfill shall be placed in layers, not to exceed twelve (12) inches and compacted to the required densities in Section B Materials not allowed for backfill include: wet materials, frozen materials, construction materials, or organic materials. B. COMPACTION 1. Within the Pavement Box All excavations (taps, trenches and emergency repairs), within the pavement box, shall be backfilled with proper materials, as stated in Sec. A, in lifts not to exceed twelve (12) inches, and compacted to a 95% density. This shall be accomplished using a proper tamping device. A hand tamp shall be used to a minimum of twenty-four (24) inches above any tap and a minimum of twelve (12) inches over any main lines. 3

5 Once fill is over these minimums, a mechanical tamp shall be used to compact the remaining backfill in the excavation. Hand tamp Whacker tamp Ramex tamp Plate tamp For all work performed by city departments, proper compaction densities of each lift shall be verified in the field using a Soil Compaction Supervisor 2 (SCS2) manufactured by MBW, Inc. Standard operating guidelines for this unit, as provided by the manufacturer, shall be strictly followed. Soil Compaction Supervisor kit Handheld unit & disposable recording disc Once the excavation has been properly backfilled, the data for the unit shall be downloaded and the data maintained for future reference. NOTE: Proper moisture content of all backfill material must be maintained to achieve the desired compacted densities. 2. Outside the Pavement Box Any excavations and trenches outside the pavement box but within any R/W s or easements shall be backfilled with proper materials as outlined in Sec. A, in lifts not to exceed twelve (12) inches, and compacted to 90% density. This includes existing areas and new construction. Any area disturbed within a public right-of-way or easement shall be backfilled and compacted properly. 4

6 NOTE: Proper moisture content of all backfill material must be maintained to achieve the desired compacted densities. C. MAINTENANCE OF CUTS After an excavation in the pavement has been properly backfilled and compacted, notice shall be given to the proper agency requesting the cut be patched. Between the time of backfilling and compacting of the excavation and the patching of the cut, any maintenance required to keep the cut safe and passable shall be the responsibility of: 1. For private contractors working with an encroachment from the city, the contractor shall be responsible for maintaining the cut until it is patched. 2. For city departments, the department making the cut shall maintain the cut For ten (10) days after the street division is notified in writing that the cut is ready for patching. However, the cut shall have proper compaction prior to notification or the cut is the responsibility of the party making the cut. Once the cut is properly compacted, the ten (10) days shall start over. 3. All cuts shall be saw cut appropriately by the person opening the pavement. All edges shall be saw cut to provide clean, straight, and vertical sides. Excess asphalt within the saw cut shall be removed by the Street division when patching is done. On trenches, the existing pavement shall be saw cut as shown in detail C01.03 in the City of Wilson Manual of Specifications, Standards, and Design. D. PATCHING (Hot mix) All patches shall adhere to the following requirements: 1. All cuts shall be patched within five (5) days after notification. 2. Patches shall be rectangular in shape with no more than four (4) interior angles of approximately 90 degrees. All edges shall provide clean, straight, and vertical sides. On trenches, the existing pavement shall be saw cut as shown in detail C01.03 in City of Wilson Manual of Specifications, Standards, and Design. 3. All edges shall be tacked. 4. Patch shall not overlap the existing pavement. 5

7 5. The depth of the patch shall be of the same thickness as the existing asphalt, with a minimum of two (2) inches. 6. All patches over two (2) inches in depth shall be placed in lifts not to exceed two (2) inches and compacted with a plate tamp if necessary. 7. Asphalt shall be placed and rolled to produce a smooth, level patch. There should not be a bump or dip. 8. Any patch which is over 20 feet long and 10 feet wide shall be patched using a machine. 9. Any excavation found not to compacted properly, shall not be patched and the party that did the excavation shall be notified and required to compact the backfill properly. A probe rod shall be used to check compaction prior to patching. Materials: Asphalt shall be S 9.5 mix. D-1. PATCHING (Asphalt overlay on top of a concrete street) Any patch in an asphalt overlay on top of a concrete street shall be prepared as outlined in Section D above with the following additional conditions: 1. The asphalt shall be cut and removed a distance of one (1) foot from the edge of the trench on the concrete on all sides. The concrete shall not be cut. 2. The new asphalt patch shall be placed over the excavation and this one (1) foot concrete shoulder. 6

8 D-2. PATCHING (Cold mix) 1. If hot mix is not available for patching, commercial cold patching material may be used. 2. It shall be installed according to the manufacturer s guidelines for installation. 3. All patches made with commercial cold patching are TEMPORARY and shall be replaced with a permanent patch using hot mix as described in Section C above. 4. Removal and replacement of cold patch with hot mix shall be done by the Streets Division. This shall be done as soon as hot mix becomes available. 5. No cold patch shall be used in any cut larger than three feet by three feet. (3 x 3 ) 7