ITEM P-152 EXCAVATION AND EMBANKMENT

152-1.1

DESCRIPTION

DESCRIPTION. This item shall consist of excavating, removing, and satisfactorily disposing of all materials within the limits of the work required to construct the landing strips, runways, taxiways, aprons, intermediate and other areas for drainage, building construction, parking, or other purposes, in accordance with these specifications and in conformity with the dimensions and typical section shown on the plans and with the lines and grades established by the engineer.

All suitable material taken from excavation shall be used in the formation of embankment, subgrade, and for backfilling as indicated on the plans or as directed by the engineer.

In case the volume of the excavation exceeds that required to construct the embankments to the grades indicated, the excess shall be used to grade the areas of ultimate development, or wasted as directed. In case the volume of excavation is not sufficient for constructing the fill to the grades indicated, the deficiency shall be supplied from borrow sources at the locations within the airport or other authorized

areas.

152-1.2

CLASSIFICATION. All material excavated shall be defined as "Unclassified Excavation" unless, in the proposal form, prices are asked and bids are taken for "Solid Rock Excavation" and "Common Excavation."

"Unclassified Excavation" shall include all excavation performed under this item regardless of the material encountered.

"Solid Rock Excavation," when this classification is provided for in the proposal, shall include all solid rock in ledges, in bedded deposits, in unstratified masses; also conglomerate deposits so firmly cemented as to present all the characteristics of solid rock and which cannot be removed without drilling and blasting. All boulders containing a volume of more than one-half (1⁄2) cubic yard will be classified as "Solid Rock Excavation."

"Common Excavation," when this classification is provided for in the proposal, shall consist of all excavation not included in "Solid Rock Excavation."

Frozen condition of any of the different classified materials taken from excavation shall constitute no claim for higher classification or for extra work on the part of the contractor.

CONSTRUCTION METHODS

152-2.1 GENERAL. The rough excavation shall be carried to such depth that sufficient material will be left above the designated grade to allow for compaction to this grade. Likewise, on embankments, sufficient material shall be placed above the designated grade to allow for compaction and settlement. Should the contractor through negligence or other fault excavate below the designated lines, he shall replace such excavation with approved materials, in an approved manner and condition, at his own expense. The engineer shall have complete control over the excavation, moving, placing, and disposition of all material, and shall determine the suitability of material to be placed in embankments. All material determined unsuitable shall be disposed of in waste areas or as directed. In general, the layer of topsoil shall not be used in fills or in subgrades but shall be handled and placed as directed.

The contractor shall inform and satisfy himself as to the character, quantity, and distribution of all material to be excavated. No pay. ment will be made for any excavated material which is used for purposes other than those designated. All spoil areas shall be leveled to a uniform line and section and shall present a neat appearance before project acceptance. The surface elevation of spoil areas shall not extend above the surface elevation of adjacent or contiguous usable areas of the airport.

Those areas outside of the pavement areas in which the top layer of soil material becomes compacted, due to hauling or to any other activity of the contractor, shall be scarified and disced to a depth of four (4) inches, as directed to loosen and pulverize the soil.

If it is necessary in the prosecution of the work to interrupt existing surface drainage, sewers, or underdrainage, conduits, utilities, or similar underground structures, or parts thereof, the contractor shall be responsible for and shall take all necessary precautions to protect and preserve or provide temporary services for same. When such facilities are encountered, the contractor shall notify the engineer who shall arrange for their removal if necessary. The contractor shall, at his own expense, satisfactorily repair all damage to such facilities or structures which may result from any of his operatïons or from negli. gence during the period of the contract.

152-2.2 EXCAVATION. Excavation shall be performed at such places as are indicated on the contract plans, to the lines, grades, and elevation shown or as directed by the engineer, and shall be made in such manner that the requirements for formation of embankments can be followed. No excavation shall be started until the engineer has taken cross-sectional elevations and measurements of the existing ground surface and has staked out the proposed work. All material encountered of whatever nature within the limits indicated shall be removed and disposed of as directed. During the process of excava tion, the grade shall be maintained in such condition that it will be well drained at all times. When directed, temporary drains and

drainage ditches shall be installed to intercept or divert surface water which may affect the prosecution or condition of the work.

The excavation material shall be handled in such a manner as to allow the selected material to be properly placed in the embankment and in the capping of pavement subgrades as determined from the soil profile and soil characteristics. This material shall be deposited within the designated areas of the airport as shown on the plans or as directed by the engineer.

If at the time of excavation it is not possible to place any material in its proper section of the permanent construction, it shall be stockpiled in approved areas for later use.

Where rock, shale, clay, hardpan or other material unsatisfactory for subgrade is encountered, it shall be excavated to a depth of at least twelve (12) inches, or such greater depth as the engineer may direct, below the contemplated surface of the subgrade. All material so excavated shall be paid for at the contract unit price per cubic yard for "Unclassified Excavation" or for "Common Excavation" or for "Solid Rock Excavation" as the case may be, when the classification for the last two items is provided for in the proposal. The portion so excavated shall be refilled with suitable selected material as specified, obtained from the grading operations or borrow and thoroughly compacted by rolling as specified. The necessary refilling will constitute a part of the embankment. Where rock cuts are made and refilled with selected material or where trenching out is done to provide for a course of pavement, the depths thus created shall be ditched at frequent intervals to provide adequate outlets for drainage.

The contractor shall make the distribution as indicated on the plans, and the widening or narrowing of the section, raising or lowering of the grade to avoid haul will not be permitted. The right is reserved to make minor adjustments or revisions in lines or grades if found necessary as the work progresses, due to discrepancies on the plans or in order to obtain satisfactory construction.

Overbreak, including slides, is that portion of any material displaced or loosened beyond the finished work as planned or authorized by the engineer. The engineer shall determine if the displacement of such material was unavoidable and his decision shall be final. All overbreak shall be removed by the contractor and disposed of as directed. Payment will not be made for removing and disposing of overbreak which the engineer determines to have been avoidable. Unavoidable overbreakage will be classified as "Unclassified Excavation" except when the contract provides for the classification of "Common Excavation" and "Solid Rock Excavation" in which case unavoidable overbreakage from slides will be classified as such.

The removal of existing structures and utilities required to permit the orderly prosecution of the work will be accomplished by local agencies unless otherwise shown on the plans. All existing foundations shall be excavated for at least two (2) feet, below the top of the subgrade and the material disposed of as directed. All foundations

thus excavated shall be backfilled with suitable material and compacted.

In cut areas the top of the subgrade under areas to be paved shall be sacrificed and compacted to a minimum depth of six (6) inches to not less than ninety-five (95) percent density as determined by the CAA compaction control tests T-611 for the class of airport involved. When the required density cannot be obtained the material shall be undercut and replaced with suitable material as directed. The depth of the undercut necessary shall be determined by the engineer. The material placed to refill the undercut portion shall be handled and compacted as specified for embankments.

Stones or rock fragments larger than four (4) inches in their greatest dimension will not be permitted in the top six (6) inches of the subgrade. The finished grading operations conforming to the typical cross section shall be completed and maintained at least one thousand (1,000) feet ahead of the paving operations.

In cuts, all loose or protruding rocks on the back slopes shall be barred loose or otherwise removed to line or finished grade of slope. All cut and fill slopes shall be uniformly dressed to the slope, cross section and alignment shown on the plans, or as directed by the engineer.

Blasting, when necessary, will be permitted only when proper precautions are taken for the protection and safety of all persons, the work, and the property. All damage done to the work or property shall be repaired at the contractor's expense. All operations of the contractor in connection with the transportation, storage, and use of explosives shall be approved by the engineer. Any approval given will not relieve the contractor of his responsibility in blasting operations.

152-2.3 BORROW EXCAVATION. When provided for the proposal, borrow excavation shall consist of excavation made from borrow areas within the limits of the airport property outside the normal grading limits, and/or from areas outside the airport, when specified, for the completion of the embankments or for other purposes. Borrow area or areas within the airport property from which borrow may be obtained will be designated. Borrow excavation shall be made only at these designated locations and within the horizontal and vertical limits as staked or as directed. On completion of borrow operations, the borrow area shall be finished to a neat and uniform grade acceptable to the engineer.

When borrow sources are outside the boundaries of the airport property, it shall be the contractor's responsibility to locate and obtain the supply subject to the approval of the engineer. The contractor shall notify the engineer sufficiently in advance of the beginning of excavation in order that necessary measurements and tests can be made. All objectionable material shall be disposed of as directed. All borrow pits shall be opened up immediately to expose the vertical face af various strata of acceptable material to obtain a uniform product. Borrow pits shall be excavated to regular lines so as to permit accurate

measurements, and shall be drained and left in a neat and presentable condition with all slopes dressed uniformly.

The borrow excavation shall be handled and placed as specified in these specifications for excavation and embankment.

152-2.4 DITCH EXCAVATION. Ditch excavation shall consist of excavating for drainage ditches such as intercepting, inlet, outlet, offtake, temporary levee construction, or any other type as designed or as shown on the plans. The work shall be performed in the proper sequence with the other construction. The location of all ditches or levees will be established on the ground. All satisfactory material shall be placed in fills; unsatisfactory material shall be placed in spoil areas or as directed. Waste or surplus material shall be disposed of as shown on plans or as directed. Intercepting ditches shall be constructed prior to the starting of adjacent excavation operations. All handwork as is necessary shall be performed to secure a finish true to line, elevation, and cross-section as designated.

The ditches constructed on the project shall be maintained to the required cross section and shall be kept free from debris or obstructions until the project is accepted. Where necessary, sufficient openings shall be provided through spoil banks to permit drainage from adjacent lands. Unless otherwise specified, no separate payment will be made for ditch excavation other than for the material removed which will be paid for at the unit price for "Unclassified Excavation" or for "Common Excavation" or "Solid Rock Excavation," as the case may be, if the proposal includes classification of these excavated materials.

152-2.5 PREPARATION OF EMBANKMENT AREA. Embankment areas shall be cleared and grubbed in accordance with the provisions and requirements in Item P-151. All depressions or holes below the ground surface, whether caused by grubbing or otherwise, shall be back-filled with suitable material and compacted to the ground surface before the construction of the embankment will be permitted

to start.

Immediately prior to the placing of the fill materials, the entire area upon which the embankment is to be placed, except where limited by rock, shall be scarified and broken by means of a disc harrow or plow or other approved equipment to a depth of six (6) inches. Scarifying shall be done approximately parallel to the axis of the fill. All roots, debris, large stones, or objectionable material that would cause interference with the compaction of the foundation or fill shall be removed from the area and disposed of as directed. A thin layer (approximately three (3) inches) of the fill material shall be spread over the scarified foundation and the whole area compacted as required in the specifications.

Where embankments are to be placed on natural slopes steeper than 3 to 1, horizontal benches shall be constructed as shown on the plans or as directed by the engineer. Suitable excavated material shall be incorporated in embankments. Payment will be made for the material excavated at the unit price for grading.

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