206.01 206-1 SECTION 206 EXCAVATION AND BACKFILL FOR STRUCTURES DESCRIPTION
206.01 This work consists of the excavation and backfill, or disposal of all material required
for the construction of structures. The excavation and disposal of excavated material for ditches and channels shall be accomplished per Section 203. All excavation and backfill for structures below the designed slope or subgrade line provided in the Contract shall be included under this item. Unless otherwise specified, structure excavation shall include all pumping, bailing, draining, and incidentals required for proper execution of the work. MATERIALS
206.02 General. All structure backfill, bed course material, and filter material will be accepted
in place.
a.Structure Backfill.
1.Structure Backfill (Class 1), (Class 2), and (Class 3). Class 1, Class 2, and Class 3 structure backfill shall be composed of non -organic mineral aggregates and soil from excavations, borrow pits, or other sources. Material shall conform to the requiremen ts of subsection 703. 08. Class of material shall be as specified in the Contract or as designated. Structure Backfill (Class 1) with mechanical reinforcement shall be used to backfill bridge abutments, unless otherwise shown on the Plans. Imported material used as structure backfill for pipes (storm sewer , cross culverts, side drains, etc.) shall meet the requirements of the Class specified and the requirements of subsection 206.02(a)3. The Contractor may substitute Structure Backfill (Flow -Fill) conforming to subsection 206.02(a)2 for Structure Backfill (Class 1) or Structure Backfill (Class 2) to backfill culverts and sewer pipes. The Contractor may also substitute Structure Backfill (Class 3) as backfill for culverts and sewer pipes.
2.Structure Backfill (Flow -Fill). Flow -Fill shall be a self -leveling low strength concrete material composed of cement, fly ash, aggregates, water, chemical admixtures or cellular foam for air -entrainment. Flow -fill shall have a slump of 7 to 10 inches, when tested per ASTM C143 or a minimum flow consistency of 6 inches when tested per ASTM D6103. Flow- Fill shall have a minimum compressive strength of 50 psi at 28 days when tested per ASTM D4832. Flash fill is a rapid setting Flow -Fill that may be used when approved by the Engineer and will be tested, accepted, and paid for as Flow -Fill. 206.02 206-2 Flow-Fill placed in areas that require future excavation, such as utility backfill shall have a Removability Modulus (RM) of 1.5 or less. Removability Modulus, RM, is calculated as follows: RM = W1.5 x 104 x C0.5 where: W = unit weight (pcf) C = 28- day compressive strength (psi) Materials for Structure Backfill (Flow -Fill) shall meet the requirements specified in the following subsections: Fine Aggregate *, 703.01 Coarse Aggregate# , 703.02 Portland Cement 701.01 Fly Ash, 701.02 Water 712.01 Air-Entraining Admixture 711.02 Chemical Admixtures 711.03 *Fine aggregate not meeting the requirements of subsection 703.01 may be used if testing indicates acceptable results for strength and air content. #Coarse aggregate not meeting the requirements of subsection 703.02 may be used if testing indicates acceptable results for strength and air content. Fly ash not meeting the requirements of subsection 701.02 may be used if testing indicates acceptable results for strength and air content. For industrial by -product aggregates (foundry sand, bottom ash, etc.) and fly ash not meeting the requirements of subsection 701.02 the Contractor shall submit a report from the supplier documenting the results of testing per the Toxicity Characteristic Leaching Procedure (TCLP) described in 40 CFR 261. The report shall include the results of TCLP testing for heavy metals and other contaminants. Materials shall not exceed the TCLP limits of 40 CFR 261.24 for heavy metals. Cellular foam shall conform to ASTM C869 and ASTM C796. Recycled broken glass (glass cullet ) is acceptable as part or all of the aggregate. Aggregate including glass must conform to the required gradations. All containers used to produce the cullet shall be empty before processing. Chemical, pharmaceutical, insecticide, pesticide, or other glass containers containing or having contained toxic or hazardous substances shall not be allowed and shall be grounds for rejecting the glass cullet. The maximum debris level in the cullet shall be 10 percent. Debris is defined as 206.02 206-3 any deleterious material that impacts the performance of the Structure Backfill (Flow - Fill) including all non -glass constituents. The Contractor may use aggregate that does not meet the above specifications if the aggregate conforms to the following gradation: Sieve Size Percent Passing 25.0 mm (1 inch) 100 75 μm (No. 200) 0 ‑10 1The amount of material passing the 75 μ m (No. 200) screen may exceed 10 percent if testing indicates acceptable results for strength and air content. The Contractor shall submit a Structure Backfill (Flow -Fill) mix design for approval before placement. The mix design shall include the following laboratory test data:
1.ASTM C231, Air content.
2.ASTM D6023, Unit Weight.
3.ASTM C143, Slump or ASTM D6103 flow consistency.
4.ASTM D4832 28- day Compressive Strength.
5.Removability Modulus (RM). The Contractor shall submit a Process Control (PC) Plan with the mix design to the Engineer. The PC Plan shall address the batching, mixing, testing, and placement of the Structure Backfill (Flow -Fill).
3.Imported Structure Backfill for Pipes . Imported Material used as structure backfill for pipes (storm sewer, cross culverts, side drains, etc.) shall be tested for compatibility with the selected pipe material. When nonreinforced concrete pipe or reinforced concrete pipe is used, the imported material shall be tested for sulfate and pH. When corrugated steel pipe , bituminous coated corrugated steel pipe or precoated corrugated steel pipe is used, the imported material shall be tested for sulfates, chlorides, pH and resistivity. When aramid fiber bonded corrugated steel pipe or corrugated aluminum pipe is used, the imported material shall be tested for pH and resistivity. When plastic pipe is selected, the imported material does not need to be tested for sulfates, chlorides, pH and resistivity. Sulfates, chlorides, pH and resistivity shall be determined by the following procedures:
1.Water soluble sulfates using CP -L 2103 Method B.
2.Chlorides using CPL 2104.
3.Resistivity using ASTM G57.
4.pH using ASTM G51. 206.02 206-4 The average of three consecutive tests shall show the imported material’s sulfate, chloride, pH and resistivity is not greater than the limits corresponding to the Pipe Class in Table 206 -1 or 206- 2 for the pipe class specified on the plans. No single test shall have a result more than 20 percent greater than that corresponding to the limit in Table 206 -1 or Table 206- 2 for sulfates, chlorides and resistivity. No single test shall have a result more than 5 percent outside the limit in Table 20 6-1 for pH. The remaining sample material from a single failing test shall be split into three equal portions. CDOT shall receive one portion, the Contractor shall receive one portion, and the remaining portion shall be retained by the Project. CDOT and the Contractor’s Lab shall retest the failed sample; if the results from those tests are within 10 percent of each other, the results will be averaged. The averaged result will be used for Contract compliance. If the results from the Labs are not within 10 percent of each other, the remaining sample portion will be sent to an independent laboratory for testing using the testing requirements specified above. The independent laboratory shall be mutually agreed upon by the Department and the Contractor. T he Independent Lab’s test result will be used for Contract compliance. If the imported material’s sulfates, chlorides, and resistivity are less than the limits and the pH is within the limits in Table 206 -1 or 206- 2, CDOT will bear all costs associated with the independent lab test. If the imported material’s sulfates, chlor ides, and resistivity is greater than the limits and the pH is outside the limits in Table 206 -1 or 206 - 2, all costs associated with independent lab testing shall be at the Contractor’s expense. Structure backfill represented by failing tests shall be removed from the project and replaced at the Contractor’s expense. Table 206 -1 SULFATE, CHLORIDE AND pH OF IMPORTED MATERIAL Pipe Class Soil Sulfate (SO4) % max. Soil Chloride (Cl) % max. Soil pH 0, 7 0.05 0.05 6.0-8.5 1, 7 0.1 0.1 6.0-8.5 2, 8 0.2 0.2 6.0-8.5 3, 9 0.5 0.5 6.0-8.5 4, 9 1 1 5.0-9.0 5, 10 2 2 5.0-9.0 6, 10 >2.00 >2.00 <5 or >9 206.03 206-5 Table 206 -2 RESISTIVITY AND pH OF IMPORTED MATERIAL SOIL SIDE Resistivity R (Ohm – cm) SOIL SIDE pH ≥ 1500 5.0-9.0 ≥ 250 3.0-12.0
b.Bed Course Material . Material shall conform to the requirements of subsection 703.07. Upon approval, aggregate base course conforming to the requirements of subsection 703.03 may be used in lieu of bed course material.
c.Filter Material . Class A, Class B, and Class C Filter Material shall conform to the requirements of subsection 703.09. Class of material shall be as specified or designated. CONSTRUCTION REQUIREMENTS
206.03 Structure Excavation and Structure Backfill . Unsuitable foundation material shall be
removed and wasted in a manner acceptable to the Engineer, and the excavated material will be paid for as structure excavation. Excavation and backfill for areas in excess of 3 feet below designed elevation will be paid for as provided in subsections 104.0 3 and 109.04. Unsuitable foundation material that is suitable for embankments and suitable surplus excavated material shall be used in the construction of embankments. Unsuitable material removed below designed elevation shall be replaced with approved material. If asbestos containing material (ACM ) is suspected or found, the ACM and the suspected ACM shall be managed per the Air Quality Control Commission Regulation N o. 8 Part B or Section 5.5 of the solid Waste Regulation 6 CCR 1007 -2, whichever applies. All work conducted on site shall be per the Colorado Department of Public Health and Environment’s Asbestos -Contaminated Soil Guidance Document or the State of Colorado’s Asbestos Contaminated Soil Statewide Management Plan (ACS), whichever is more recent at the time of advertisement, and per subsection 250.07(d). Rock, hardpan, or other unyielding material encountered in trenches for culvert pipe or conduit shall be removed below the designed grade for a minimum depth of 12 inches. This extra depth excavation shall be backfilled with loose Structure Backfill (Class 1) or other approved material. The base of structure backfill shall be scarified to a depth of 6 inches and compacted with moisture and density control before placement of any structural element or structure backfill. The type of compaction shall be the same as that required for Structure Backfill (Class 2), as specified below. Backfill shall consist of approved materials uniformly distributed in layers brought up equally on all sides of the structure. Each layer of backfill shall not exceed 6 inches and shall be compacted to the required density before successive layers are placed. Structure Backfill (Class 1) shall be compacted to a density of at least 95 percent of maximum dry density determined per AASHTO T 180 as modified by CP 23. Backfill shall be compacted at plus or minus 2 percent of Optimum Moisture Content (OMC). 206.03 206-6 Structure Backfill (Class 2) shall be compacted to a density of at least 95 percent of maximum dry density. The maximum dry density and OMC for A -1, A-2-4. A-2-5 and A -3 materials will be determined per AASHTO T 180 as modified by CP 23. The maximum dry density and OMC for all other materials will be determined per AASHTO T 99 as modified by CP 23. Materials shall be compacted at plus or minus 2percent of Optimum Moisture Content (OMC). Materials having greater than 35 percent passing the 75 µm (No. 200) sieve shall be compacted at 0 to 3 percent above OMC. Pipes, culverts, sewers, and other miscellaneous structures outside the roadway prism and not subjected to traffic loads shall be backfilled in layers as described above but shall be compacted to the density of the surrounding earth. The excessive use of water during backfilling operations will not be permitted. Compaction equipment or methods that produce horizontal or vertical earth pressures, which may cause excessive displacement or overturning, or may damage structures, shall not be used. Backfill material shall not be deposited against newly constructed masonry or concrete structures, until the concrete has developed a compressive strength of 0.8f'c, except in cases where the structures support lateral earth pressure. Concrete compressive strength for structures supporting lateral earth pressure shall conform to subsection 601.12(o). Concrete compressive strength shall be determined by maturity meters . Backfill at the inside of bridge wingwalls and abutments shall be placed before curbs or sidewalks are constructed over the backfill and before railings on the wingwalls are constructed. Unless otherwise indicated in the Contract or directed, all sheeting and bracing used in making structure excavation shall be removed by the Contractor before backfilling. Structure backfill placed at bridge piers in waterways and water channels, that does not support embankments, pavements, or slope protection, will not require compaction. Structure Backfill (Flow -Fill) shall not be compacted. The maximum layer thickness for Structure Backfill (Flow -Fill) shall be 3 feet unless otherwise approved by the Engineer. The Contractor shall not place Structure Backfill (Flow - Fill) in layers that are so thick that they cause damage to culverts, pipes, and other structures or that they cause formwork or soil failures during placement. Structure Backfill (Flow -Fill) shall have an indention diameter less than 3 inches and the indention shall be free of visible water when tested per ASTM D6024 by the Contractor before placing additional layers of Structure Backfill (Flow - Fill). Testing Structure Backfill (Flow -Fill) per ASTM D6024 will be witnessed by the Engineer. Damage resulting from placing Structure Backfill (FlowFill) in layers that are too thick or from not allowing sufficient time between placements of layers shall be repaired at the Contractor’s expense. The Contractor shall secure culverts, pipes and other structures to prevent floating and displacement of these items during the placement of the Structure Backfill (Flow -Fill). 206.04 206-7 When Flash Fill is used, it shall be batched with a volumetric mixing truck. Volumetric mixing trucks used to produce Flow -Fill and Flash Fill shall have a computer batching system, capable of producing the approved mix design and printing tickets. For Flash Fill, the batch weights of cement and fly ash per cubic yard shall be within 2 percent of the mix design batch weights and the batch weight of water per cubic yard shall be within 2 percent of the mix design batch weight. Before the placement of structure backfill (Flow -Fill), the Contractor shall sample the structure backfill (Flow -Fill) per ASTM D5971. The Contractor shall test the structure backfill (Flow -Fill) unit weight per ASTM D6023. For Flash Fill, the measured unit weight shall be within 5.0 percent or 5.0 pounds per cubic foot, whichever is larger, of the approved mix design unit weight. The Contractor shall test the structure backfill (Flow -Fill) for slump per ASTM C143 or flow consistency according to ASTM D6 103. The Contractor shall sample and test the first three loads of Structure Backfill (Flow -Fill) for each placement and then randomly once every 50 cubic yards. Sampling and testing will be witnessed by the Engineer. When Structure Backfill (Flow -Fill) is placed in areas that require future excavation, the unit weight of the placed Structure Backfill (Flow -Fill) shall not exceed the unit weight of the approved mix design by more than 2.0 pounds per cubic foot. Structure Backfill (Flow -Fill) shall not be allowed to freeze during placement and until it has set sufficiently according to ASTM D6024. Frozen Structure Backfill (Flow -Fill) shall be removed and replaced at the Contractor’s expense. When the Contractor substitutes Structure Backfill (Flow -Fill) for Structure Backfill (Class 1) or (Class 2), the trench width may be reduced to provide a minimum 6 -inch clearance between the outside diameter of the culvert and the trench wall.
206.04 Bed Course Material. Construction requirements for bed course material for sidewalks
and curbing shall conform to the applicable requirements of Sections 608 and 609.
206.05 Filter Material. Construction requirements for filter material for subsurface drains
shall conform to the applicable requirements of Section 605. Filter material shall be placed behind bridge abutments, wingwalls, and retaining walls as provided in the Contract and per the following requirements: When provided in the Contract, wall drain outlets shall be backed with sacked filter material conforming to the gradation requirements for coarse aggregate No. 3 or No. 4 set forth in Table 703-2. Filter material shall be placed in horizontal layers along with and by the same methods specified for structure backfill. 206.06 206-8 METHOD OF MEASUREMENT
206.06 Structure excavation, structure backfill, and bed course material will not be
measured but will be the quantities designated in the Contract. When field changes are ordered or when there are errors on the plans, quantities will be measured as follows:
a.For bridges and irregular shaped structures, quantities will be computed to neat lines 18 inches outside and parallel to the outline of the revised foundation plan or as shown on the plans.
b.For pipes, a profile will be made along the bottom of the center line extending 18 inches beyond the end of the structure, including end sections. Material excavated between this profile and a profile 1 foot above the top of the pipe will not be measured for payment but shall be included in the bid price for the pipe. In excavation sections the area above the profile 1 foot above the top of the pipe and below the limits of roadway excavation will be multiplied by the width shown on the plans to obtain the volume of structure excavation measured for payment. In embankment sections the area above the profile 1 foot above the top of the pipe and below the natural ground will be multiplied by the width shown on the plans to obtain the volume of structure exca vation measured for payment.
c.Backfill and filter material will be the calculated volume of material lying within the prism shown on the plans, from which shall be deducted the volume occupied by the structure.
d.Bed course material will be the calculated volume of material lying within the prism shown on the plans. BASIS OF PAYMENT
206.07 The accepted quantities will be paid for at the contract unit price for each of the
pay items listed below that appear in the bid schedule. Payment will be made under: Pay Item Pay Unit Structure Excavation Cubic Yard Structure Backfill (Class ) Cubic Yard Structure Backfill (Flow -fill) Cubic Yard Bed Course Material Cubic Yard Filter Material (Class ) Cubic Yard Compaction, water, and all other work necessary to complete the above items will not be measured and paid for separately but shall be included in the work. Structure backfill, including bed course material, for pipes and end sections will not be measured and paid for separately, but shall be included in the work. Where only end section work is required the structure excavation quantity and the structure back fill quantity will not be measured and paid for separately but shall be included in the work. When the Contractor substitutes Structure Backfill (Flow Fill) for Structure Backfill (Class 1) or (Class 2), there will be no adjustment in the price or the quantity paid for structure excavation or structure backfill as a result of reducing the trench width. 206.09 206-9 SHORING DESCRIPTION
206.08 This work consists of shoring specific areas designated in the Contract.
MATERIALS AND CONSTRUCTION REQUIREMENTS
206.09 The Contractor shall locate, size, design, and construct shoring that provides all
necessary rigidity, and supports the loads imposed to facilitate construction as shown on the plans. Shoring used to facilitate construction is considered temporary and shall have a design life 1 -1/2 times the expected construction service lif e, with a maximum design life of three years. When the height of shoring exceeds 5 feet above the base of the excavation, the Contractor shall submit working drawings per subsection 105.02. The drawings shall be submitted to the Engineer for information only. The drawings shall be electronically sealed by the Contractor’s Engineer. The Contractor shall design for internal and external stability of temporary shoring such as but not limited to bearing capacity, settlement, sliding, overturning, internal compound stability, and global stability. All proof and verification testing of the shoring elements shall be the responsibility of the Contractor and results shall be reported to the Engineer the day after the testing was performed. All proof and verification testing of the shoring elements shall be the responsibility of the Contractor. For soil nail walls, a minimum of one proof test shall be performed per the Revision of Section 504 Soil Nail Wall, and test results shall be reported to the Engineer the day after the testing was performed. The Contractor shall conduct additional proof and verification testing at the Engineer’s request. Sufficient corrosion protection shall be provided in consideration of the temporary shoring design life and is the responsibility of the Contractor. Temporary shoring shall be designed for actual construction- related loads, such as phasing, stockpiles, and operation of large cranes or other large equipment near the area of the shoring. These drawings shall be signed by the Contractor and provided to the Enginee r at least 10 days before start of work. Shoring construction shall conform with the shoring drawings provided to the Engineer. The Contractor shall conduct any necessary site -specific evaluation necessary to ensure shoring design, construction and performance. The Contractor shall have performed and documented an independent review of their shoring design and drawings at designated areas before submittal. The Contractor’s Engineer shall electronically seal the independent review shoring design and drawings . The shoring plans shall detail the methods to control site drainage during the life of the shoring. The Contractor shall actively control drainage and surface runoff during the duration of construction to direct run off away from the shoring areas above an d behind the shoring. A shoring site drainage quality control plan shall be included as part of the Contractor’s Engineer’s shoring plans and shall be part of the submittal to the Engineer. The plan shall include measures to prevent ponding water near the shoring area and maintenance of drainage to convey water away from and around the shoring excavation vicinity. 206-10 If the embankment, construction, traffic, or any other surcharge is in excess of what the original shoring was designed for and is to be placed adjacent to the shoring, the Contractor shall provide a signed letter from the Contractor’s Engineer before the load placement stating that the shoring will support the additional load. Shoring shall be designed and constructed per the requirements listed in this specification along with requirements in current AASHSTO and FHWA design manuals including, but not limited to:
1.AASHTO Construction Handbook for Bridge Temporary Works including Division I.
2.Section 5 of the AASHTO LRFD Bridge Design Specifications for allowable stress or load factor design ; or
3.AASHTO LRFD Bridge Design Specifications including current interims for load and resistance factor design. If a shoring type is to be used that is not detailed in these three documents, the shoring type design method will need to be submitted to the Engineer. The Contractor’s Engineer shall be on-site and perform construction inspection of the shoring during the first two days of active shoring construction, during any shoring element verification testing, and at the completion of shoring construction. Shoring drawings shall include the following information:
1.The size and grade of all structural materials
2.Design notes, including design assumptions, including loading, and construction details.
3.Detailed plans for managing and maintaining shoring surface and subsurface drainage conditions for the project duration.
4.Where applicable, restrictions on heavy equipment placement at specific locations adjacent to the shoring
5.Areas determined by the Contractor’s Engineer where dewatering of the shored excavation will be required, and a description of the requirements (i.e., head added by the pump, flow rate, minimum pump size, etc.) and methods to be used for dewatering.
6.All other information determined by the Contractor’s Engineer to be pertinent to the design and successful construction of the shoring. Drawings for temporary shoring that requires structural designs shall include the following information:
1.Individual site- specific geotechnical properties for each shoring location based on the plan, review of the Geotechnical Report per subsection 102.05, or from a geotechnical evaluation performed by the Contractor at their own expense.
2.Global stability analysis showing that the shoring will be stable under the loads placed on it and construction conditions encountered during construction. 206.11 206-11 The Contractor’s Engineer may assign an on -site representative, to perform construction field oversight, by submitting documentation of experience to the Engineer 10 days before starting shoring construction for review and the Engineer’s acceptance. Before placing construction or traffic loads on or immediately adjacent to the supported earth, the Contractor’s Engineer for the shoring shall certify in a n electronically sealed letter that shoring materials and construction have been inspected and that all shoring, materials, and construction are in conformity with the shoring drawings. A copy of this certification shall be submitted to the Engineer. METHOD OF MEASUREMENT
206.10 Shoring will not be measured but will be paid for as a single lump sum for each Area
described on the plans. Incidental shoring work or shoring in locations other than those described on the plans will be as determined by the Contractor and will not be measured and paid for separately but shall be included in the work. BASIS OF PAYMENT
206.11 The accepted quantities of shoring measured as provided above will be paid for at the
contract unit price bid. Payment will be made under: Pay Item Pay Unit Shoring (Area ___) Lump Sum Payment for shoring will be full compensation for all labor, materials, and equipment required to design, construct, test, maintain, and dewatering. Removal of the shoring shall include removal of all shoring elements. The removal area shall be specified in the plans. Removal of shoring will not be measured and paid for separately but shall be included in the work. The Department will pay for additional proof and verification testing, as requested by the Engineer, per subsection 109.04. Other incidental shoring that is not included as a pay item will not be measured and paid for separately but shall be included in the work. 206.11 206-12 THIS PAGE INTENTIONALLY LEFT BLANK 207.01 207-1 SECTION 207 TOPSOIL DESCRIPTION
207.01 This work consists of salvaging and stockpiling topsoil , and excavating suitable topsoil
from stockpiles, contractor sources, available sources, or from the approved natural ground cover to place on designated areas. P lacing of topsoil upon constructed cut and fill slopes after grading operations are completed is included . MATERIALS
207.02 Topsoil shall consist of loose friable soil from the zone of major root development free
of subsoil, refuse, stumps, woody roots, rocks, brush, noxious weed seed and reproductive plant parts from current state and county weed lists, heavy clay, hard clods, toxic substances, or other material that would be detrimental to its use on the project. Wetland topsoil material shall consist of the moist, organic soil, including any existing wetland vegetation and seeds, to be excavated from areas as shown on the plans or as directed. CONSTRUCTION REQUIREMENTS
207.03 Wetland topsoil material shall be excavated from the designated area to a maximum
depth of 12 inches, or as otherwise designated, and placed within 24 hours in the specified area. The Contractor shall prepare the relocation site to elevations specified and approved by the Engineer before excavating the wetlands. If the Engineer determines that this is not possible, then the Contractor shall stockpile the material in an approved area, to remain undisturbed until the relocation site has been prepared. Storage time within the stockpile shall be as short as possible. Wetland topsoil material shall be placed over the prepared relocation areas to a depth of 12 inches, or as otherwise designated. Topsoil within the limits of the roadway shall be salvaged before beginning hauling, excavating, or fill operations by excavating and stockpiling the material at designated locations in a manner that will facilitate measurement, minimize sediment damage, and not obstruct natural drainage. Topsoil shall be placed directl y upon completed cut and fill slopes whenever conditions and the progress of construction will permit. Topsoil shall be placed at locations and to the thickness provided in the Contract and shall be keyed and tracked to the underlying material without creating a compacted surface by the use of harrows, bulldozers, rollers, or other equipment suitable for th e purpose. Salvaged topsoil exceeding the quantity required under the Contract shall be disposed of at locations acceptable to the Engineer.
Source: Colorado Standard Specifications for Road and Bridge Construction, 2023 Edition. Pages 217–228 of 943.