99 SECTION 206 DESCRIPTION
206.01.01 General. This work consists of the removal of material encountered for the construction of selected
structures and other excavation specifically designated as structure excavation. This work also includes the work of disposing of surplus material and cleaning up the sites. Structure excavation includes dewatering and the construction or installation of all cofferdams, cribs, shoring, and other facilities which may be necessary to perform the excavations and the subsequent removal of such facilities except where they are required or permitted to remain in place. It also includes the necessary clearing and grubbing within the proposed structure area and removing old structures or parts thereof as required if the proposal does not include separate bid items for such work. For specific requirements pertaining to the excavation involved in the installation of pipe culverts and underground piping, attention is directed to those Sections of these specifications governing such work. Design and construct shoring, cribbing, or cofferdams as required. Construct safe and adequate shoring, cribbing, or cofferdams to provide the necessary rigidity and support the loads imposed. Submit 6 sets of design calculations along with detailed drawings of the shoring, cribbing, or cofferdams for approval according to Subsection 105.02. Such design calculations and drawings shall be prepared and stamped by a professional engineer registered as a Civil Engineer in the State of Nevada. If such plans are not satisfactory make such changes in them as may be required. Do not begin construction of such shoring, cribbing, or cofferdams until the drawings are approved. Allow 30 days for Department review and approval of complete excavation shoring shop drawings. Allow an additional 60 days for such shop drawings that also require Railroad approval. Do not begin excavation shoring construction until shop drawings have been approved. No additional time will be provided for shop drawings submittals that are returned for correction by either the Department or the Railroad. Follow OSHA safety regulations (29 CFR, Part 1926, Subpart P, Excavations) for sloping the sides of excavations, using shoring and bracing, and for using other safety features. When sides of excavations are sloped for safety considerations submit, for informational purposes, one copy of the design that demonstrates conformity with OSHA regulations. Where support systems, shield systems, or other protective systems are to be used, submit design calculations along with detailed drawings that demonstrate conformity with OSHA regulations. Submit the design calculations and detailed drawings according to Subsection 105.02.
206.01.02 Classification. Classification of structure excavation will not be made on the basis of materials or
conditions encountered. Classification of excavation, if made, will be on the basis of the material removed between certain elevations, and such classification as shown on the plans or set forth in the Special Provisions shall not be changed regardless of the material encountered. CONSTRUCTION
206.03.01 General. Give notification at least 2 weeks in advance of the beginning of excavation so that
elevations and measurements may be taken of the existing ground before it is disturbed and of existing substructure units within the limits of excavation for structures before they are removed. Material excavated or removed before these measurements have been taken will not be paid for. Excavate to the established elevations and dimensions. Consider the elevation of the bottoms of footings as shown on the plans as approximate only. Changes in dimensions or elevation of footings as may be necessary to secure a satisfactory foundation may be ordered in writing. Compact culvert pipe and structure foundations to not less than 90% of the maximum density as determined by Test Method No. Nev. T108. The in-place density will be determined by Test Method No. Nev. T102 or T103. Cut rock or other hard foundation material to a firm surface, either level, stepped, or serrated. Clean the excavation of loose material. Clean out and fill seams and crevices with concrete mortar or grout. Should foundation excavation be below grade, backfill to the required elevation with backfill or foundation fill with no additional payment. 206 STRUCTURE EXCAVATION 100 Dewater wet excavations for inspection and for construction of foundations unless otherwise provided. Utilize suitable excavated material for backfilling or in embankments. Dispose of surplus or un suitable material so as to cause no obstruction to flow of streams, or otherwise impair the efficiency or appearance of the structure. Dispose in such a manner as to prevent damage to property or the creation of unsightly conditions, and do not place where it will interfere with the operation of drains or impair the roadway ditches, etc.
206.03.02 Inspection. After each excavation is completed, give notification , and do not place materials therein
until the depth of excavation and the character of the foun dation material ha ve been approved. METHOD OF MEASUREMENT
206.04.01 Measurement. Structure excavation will be measured by the cubic meter (cubic yard) of material
excavated and placed as required. The estimated quantities shown on the plans, plus or minu s authorized quantity changes, will be the quantity used for payment. The Engineer or the Contractor may, however, request recalculation of quantities. Submit request for recalculation of quantities in writing. When quantities are recalculated, the recalc ulated quantities will be used for payment. The volume of water or any other liquid will not be included in the measurement for payment. The volume of mud, muck, or similar semi -solid matter not resulting from construction operations and which cannot be p umped or drained away shall be included. BASIS OF PAYMENT
206.05.01 Payment. The accepted quantities, measured as provided above, will be paid for at the contract
price per unit of measurement for the pay item listed below that is shown in the proposal. Payment will be full compensation for the work prescribed in this Section. No compensation will be made for the removal and disposal of material which may come into an excavation from outside the designated limits or for the removal and disposal of swell material resulting from the driving of piles in an excavation. The limits of structure excavation shown in the plans shall be used for the method of measurement and payment only. Make the structure excavation limits outside the vertical planes 450 mm (18 in.) outside the structures according to the OSHA safety regulations. There will be no additional compensation for protective systems required by the OSHA regulations. When plan quantities of structure excavation are based upon the use of shoring, no incr ease in structure excavation quantity will be allowed when shoring is eliminated. When an item for structure excavation does not appear in the proposal, structure excavation will be considered as incidental to the installation of the structure and compens ation shall be considered as being included in the contract prices for other items of work. Payment will be made under: Pay Item Pay Unit Structure Excavation ................................ ................................ ................................ ................................ ......... Cubic Meter (Cubic Yard) 101 SECTION 207 BACKFILL DESCRIPTION
207.01.01 General. This work consists of placing and compacting backfill or granular backfill material in
excavations for bridges, retaining walls, headwalls, culverts, and other structures. This work also consists of furnishing and placing slurry cement backfill as shown on the plans, or as an alternative to backfill or granular backfill. Applications include use as structural fill, pipe encasement, or pipe and trench backfill as approved. For placement adjacent to bri dge structures, prior approval by the Bridge Engineer is required. MATERIALS
207.02.01 General. Material shall conform to the following Subsections:
Backfill ................................ ................................ ................................ ................................ ................................ .... Subsection 704.03.10 Granular Backfill ................................ ................................ ................................ ................................ ...................... Subsection 704.03.11
207.02.02 Slurry Cement Backfi ll. Slurry cement backfill shall consist of a workable mixture of various
combinations of aggregate, cement, mineral admixtures, liquid admixtures, and water. Aggregate shall consist of a concrete, grout, or mortar aggregate as specified in Section 706. Cement shall meet the requirements of Section 701. All approved cement types and blended cements or combination thereof may be used. Mineral admixtures shall meet the requirements of Section 702. For ap proval, submit a mix design stamped by a Professional Engineer registered in the State of Nevada to ensure accordance with performance specifications listed herein. The mix design shall include a list of all ingredients, the source of materials, gradations of aggregates, types of admixtures, dosage rates, and batch weights. A change in the source of materials, gradation, or addition or deletion of admixtures may necessitate a new mix design and trial batch. Provide test data from a n accredited laborator y showing that the proposed mix design meets the performance specifications herein. Accreditation shall be obtained from the American Association of State Highway and Transportation Officials (AASHTO) or the American Association for Laboratory Accreditation (A2LA). A mix design having prior acceptance by the Department, local municipalities, or utility companies may be approved if documentation of test results and past field performance is provided. Submit slurry cement mix designs conforming to one of the following classes of flowable fill, A or B, de pending on the application. The type of application shall be shown on the plans or be as determined by the Contractor and approved. Determine proportioning as shown on the approved mix design. The trial batch and subsequent placements shall produce a mix c onsistency that will result in a flowable self -leveling product at the time of placement. Excavatable Non-Excavatable Class A B 28 Day Strength .......................... 340-1,400 kPa (50 -200 psi) ............. 1,400 -6,900 kPa (200 -1,000 psi) Air Content ................................ ............. 5% Min. ................................ ............... 5% Min. Subsidence ................................ ............ 1% Max. ................................ ............. 1% Max. The use of air entrainment, air generators, or foaming agents may be needed to meet the performance specifications. The 28 day compressive strength testing and sampling will follow the procedure set forth in Test Method Numbers Nev. T 428 and ASTM C39, except cylinders shall not be rodded during sampling. The air content will be determined by Test Method No. Nev. T431 or T432 . Subsidence will be tested according to ASTM C940, except a standard 152 mm by 305 mm (6 in. by 12 in.) cylinder may be used for measurement purposes. Subsidence is defined as settlement or bleeding and shall not exceed 1%. Mixtures that require placement by use of a concrete or grout pump will be allowed a maximum subsidence of 2%. Slump tests may be performed on a random basis using Test Method No. Nev. T438 for the purpose of controlling consistency at the job site.