Special Provision Item P-152 Excavation and Embankment

Transcription

1 Special Provision Item P-152 Excavation and Embankment DESCRIPTION This item shall be constructed in conformity with FAA Standard Specification "Item P-152 Excavation and Embankment, except as herein modified by this Special Provision. The following modify, change, delete from or add to the FAA Standard Specification. Where any paragraph, subparagraph or clause of the Standard Specification is modified or deleted by these provisions, the unaltered parts of that paragraph, subparagraph or clause shall remain in effect a. Unclassified Excavation. Add the following: Unclassified Excavation shall include all excavation, including topsoil salvaging and stockpiling, embankment, and subcut in excavation areas below finished subgrade as required. All areas shown on plans as "Grade to Drain" shall require surface shaping with a blade to provide a path for water to drain away from the area or ditch section. The cost of this grading shall be incidental b. Borrow Excavation. Add the following: Borrow Excavation shall include all excavation from sources shown on the plans or from sources provided by the Contractor. Topsoil removed from borrow areas will not be considered borrow. Borrow areas available on-site are shown on the plans. The Contractor shall provide and maintain the haul roads required to transport borrow from the borrow pit to the embankment areas. Any temporary culverts or approaches shall be incidental to the cost of borrow and shall be removed by the Contractor when no longer needed. When finished, the Contractor shall leave the borrow site in a neat condition that is acceptable to the Owner. CONSTRUCTION METHODS General. Delete first paragraph and replace with the following: Water hauling equipment shall be equipped with water-tight connections and a water-tight tank having a minimum capacity of 1000 gallons. The distributor shall be equipped with a spraying device and be capable of evenly distributing water uniformly over the designated area. The Contractor shall provide his own source of water for compaction. If no separate bid item for water is included in a Division in the Bid Proposal, the cost of providing necessary water shall be incidental to the work performed under that division. The Contractor shall furnish and continuously operate heavy duty discs with serrated blades a minimum of 18-inch in diameter which meet the approval of the Engineer whenever embankment material is placed in the proposed work to accomplish the following results: a) To thoroughly mix the soils as each lift is placed in the embankment areas. SP Item P-152 Excavation and Embankment 1

2 b) To mix and attain uniform moisture content throughout each lift of embankment before the compaction process is started. c) To aid the penetration of water into each soil layer in the excavation and borrow areas before it is placed into the embankment. d) To reduce the moisture content in the soils proposed for use or are already in place in the embankment areas in order to meet the moisture requirements of the governing specifications or special provisions. Provide and utilize, as required to mix thoroughly, one (1) tractor disc unit for 60 cubic yards of working scraper capacity or portion thereof. The Contractor shall furnish both rubber-tired or sheepsfoot rollers for the compaction procedure. Generally, these types of compaction equipment will produce the required densities with a reasonable number of passes when moisture conditions and thickness of lift are properly controlled. Both types of rollers are required because variable soil characteristics may require different equipment or a combination of the both types. Rubber-tired equipment is generally needed for rolling during the final shaping operations for most soils. Such a roller shall be of a capacity so that the minimum contact pressure is 90 psi. The contact pressure is defined as the "average ground contact pressure", expressed in psi, obtained when the wheel load in pounds is divided by the gross contact area in square inches of the tire. The Contractor shall furnish the Engineer with any data necessary to determine the contact pressure for the full range of the manufacturer's recommended wheel loads and tire inflation pressures. The sheepsfoot roller to be furnished may be any one (1) of the following types: Single drum, dual drum, self-propelled having one or more drums, vibratory sheepsfoot or a self-propelled segmented steel-lugged type. Some soils, such as clean sands of uniform size, cannot be successfully compacted by a sheepsfoot roller. The roller shall also be of a type that it may be filled with water or sand in order to gain the weight desired for the compaction of the soils encountered on the project. It shall be the Contractor's responsibility to meet the requirements of the specifications for moisture control and compaction requirements with the equipment and construction procedures specified herein without any additional costs to the Owner. Therefore, the Contractor shall exercise special attention to the existing predominant types of soils on the project and base the selection of roller types to be furnished based on that knowledge. The Contractor shall also determine the moisture conditions in the proposed excavation, borrow areas to his own satisfaction, and base the size and quantity of water tanks needed to keep the rate of watering consistent with the progress of the embankment construction based on that information. The excavation of the subsoil material may not be able to be accomplished with normal earthmoving equipment and/or operations. The Contractor shall consider this in determining excavation methods for these items. If more material is required to construct the section to planned grade as shown, the Engineer reserves the right to modify planned ditch slopes or width to obtain additional material. The additional material will be paid for at the bid price for Unclassified Excavation EXCAVATION. Delete the first sentence of paragraph one and replace with the following: No excavation shall be started until the work has been staked out by the Engineer and the Engineer has obtained elevations and measurements of the ground surface. Add the following: If directed by the Engineer, waste excavation material not suitable for embankment shall be hauled to the borrow or waste area and disposed of there. The cost of removing and replacing topsoil from waste areas shall be paid for one 2 SP Item P-152 Excavation and Embankment

3 (1) time at price bid for "Unclassified Excavation" as measured in the stockpile by either the average end area method or prismoidal method. Should any on-site gravel deposits be discovered during excavation activities, the gravel material shall be placed in embankment areas as directed by the Engineer e Compaction Requirements. Delete first paragraph and replace with the following: The subgrade shall be compacted to a density of not less than 90 percent of the maximum density as determined by ASTM D 698. Moisture content of compacted subgrade shall be between minus two (2) percent and plus two (2) percent of optimum moisture. One (1) in place density test shall be made per each 2000 square yard area of subgrade under all areas BORROW EXCAVATION. Add the following: When borrow sources are outside the airport property, the Contractor shall be responsible for any royalty fees or other charges by the pit owner PREPARATION OF EMBANKMENT AREA. Delete the first paragraph and replace with the following: Remove, salvage and stockpile four (4) inches of topsoil from where embankment is to be constructed, and stockpile for later reuse on seeded areas. Subgrade shall be scarified to a minimum depth of 12 inches and mixed prior to placing or compacting fill or base material. This area shall then be compacted as indicated in section FINISHING AND PROTECTION OF SUBGRADE. Delete the last paragraph and replace with the following: The subgrade shall be proof-rolled by the Contractor using suitable equipment (such as a fully loaded water truck or fully loaded dump truck or a tractor-trailer combination), approved for this purpose by the Engineer, before placing and/or spreading operations are started for the next course of the pavement section. Any ruts or soft yielding areas shall be corrected at the Contractor's expense before the next course of material is placed thereon. Material shall not be placed on frozen subgrade. All costs associated with proof-rolling shall be included in the price bid for Unclassified Excavation P TOPSOIL. Delete and replace with the following: When topsoil is specified or required as shown on the plans or under Item T-905, it shall be salvaged from stripping or other grading operations as follows: Topsoil shall be removed from all excavation and embankment areas and stockpiled on the right-of-way outside the grading limits. If additional area outside the right-of-way is required to stockpile topsoil, the Contractor is responsible for obtaining this additional area. Topsoil shall be removed to a depth of four (4) inches. If additional topsoil exists below the four (4) inches removed, the remaining topsoil shall be removed and placed in the embankment under areas not to receive pavement and mixed thoroughly with other soil types. All stockpiled topsoil shall be respread evenly over the entire area disturbed by the construction operations that are scheduled to be seeded. Payment will be paid for under the price bid for Topsoiling (On-site) as provided in Item T-905. Topsoil from on site borrow areas shall be removed to its full depth and stockpiled. The Engineer shall determine the depth of the topsoil. Salvaging, stockpiling, and respreading of topsoil from the stockpile for on-site borrow areas shall be measured separately in the stockpiles and paid for as Borrow Area Topsoil (On Site). Borrow area topsoil removal and replacement will not be included for payment as "Borrow (On Site)" or Unclassified Excavation. Salvaging and stockpiling topsoil which originated from excavation and embankment areas will not be measured separately, but will be included and paid for as Unclassified Excavation as provided for in Item P-152. The quantities shown for unclassified excavation include existing topsoil removed along with subgrade excavation. SP Item P-152 Excavation and Embankment 3

4 The re-handling of the stockpiled topsoil from excavation, embankment, preparing the ground surface, and spreading and compacting the topsoil shall be paid for under the price bid for "Topsoil (On Site)" as provided in Item T Add the following: METHOD OF MEASUREMENT Contract Quantity Payment. The plan quantities of excavation for which unclassified payment will be made are those shown in the contract for the various items, provided the project is constructed essentially to the lines and grades shown on the plans. Final field cross-sections shall be employed if the following changes have been made: a) Plan width of embankments or excavations are changed by more than plus or minus 1.0 foot (0.3 meter); or b) Plan elevations of embankments or excavations are changed by more than plus or minus 0.5 foot (0.15 meter). When disagreement exists between the Contractor and the Engineer as to the accuracy of the plan quantities in the entire project, either party shall have the right to request and cause the quantities involved to be measured. When the quantities are measured for payment, the original plan cross-sections shall be used as the original field cross-sections. Additional cross-sections may be interpolated at points where necessary to more accurately determine the quantities. If the Contractor requests field measurement of the final quantity and the final quantity so determined varies by less than three (3) percent of the original contract quantity shown on the plans and/or bidder's proposal, the cost for re-measuring and computing the earthwork quantity will be deducted from the moneys due to the Contractor for the completed item. Topsoil shall be measured as per SP-T-905. Water used for compaction purposes on subgrade, subbase, subgrade preparation or aggregate base will be measured by the 1,000 gallon ('M'gal.) in the hauling vehicle if shown for payment in the Bid Proposal. Water used for dust control or haul road maintenance shall be incidental to other items. Scarify and Recompact Subgrade, as shown in the project plan sheets, shall not be measured for payment and shall be considered incidental to Unclassified Excavation Add the following: For payment specified by the cubic yard (cubic meter), measurement for all excavation can be computed by the prismoidal method. The Engineer shall determine the measurement method depending on the shape of the area to be measured. Add the following provision to this item: BASIS OF PAYMENT When contract quantity is shown for payment on the bidder's proposal, payment will be made at the unit price bid per cubic yard for the quantity of unclassified excavation shown therein, unless additional quantities of unclassified excavation are added or deleted due to changes during construction. Water will be paid for at the unit price bid per 'M'gal. If no quantity for water is indicated on the Bid Proposal, it will be incidental and no direct payment will be made. 4 SP Item P-152 Excavation and Embankment

5 Topsoil soil shall be paid for as per SP-T-905. All costs for the on-site borrow shall be included in the bid price and paid for one time as Borrow (On Site). Scarify and Recompact Subgrade, as shown in the project plan sheets, shall be considered incidental to Unclassified Excavation and no direct payment will be made. Delete the last paragraph of this section and replace it with the following: Payment will be made under: Item P Item P Item P Unclassified Excavation-per cubic yard (cubic meter) Water-per M Gal. Borrow (On Site)-per cubic yard (cubic meter) END OF ITEM SP-P-152 SP Item P-152 Excavation and Embankment 5