Section 204 — Excavation and Embankment
Description
204.01This work consists of excavating material and constructing embankments. This work also includes providing, hauling, stockpiling, placing, disposing, sloping, shaping, compacting, and finishing earthen and rocky material.
204.02Definitions.
(a)Excavation. Excavation consists of the following:
(1)Roadway excavation. Material excavated from within the right- of-way or easement areas, except subexcavation covered in Subsection 204.02(a)(2) and structure excavation covered in Sections 208 and 209. Roadway excavation includes all material encountered regardless of its nature or characteristics. (2) Subexcavation. Material excavated from below subgrade elevation in cut sections or from below the original ground- line in embankment sections. Subexcavation excludes the work required by Subsection 204.05 or 204.06.
(3)Borrow excavation. Material used for embankment construction that is obtained from outside the roadway prism. Borrow excavation includes unclassified borrow and select borrow.
(b)Embankment construction. Embankment construction consists of placing and compacting roadway or borrow excavation. This work includes:
(1)Preparing foundations for embankments;
(2)Constructing roadway embankments;
(3)Benching for side- hill embankments;
(4)Constructing dikes, ramps, mounds, and berms; and
(5)Backfilling subexcavated areas, holes, pits, and other depressions.
(c)Conserved topsoil. Excavated material conserved from the roadway excavation and embankment foundation areas that is suitable for growth of grass, cover crops, or native vegetation. (d) Waste. Excess or unsuitable roadway excavation and subexcavation that cannot be used.
Material
204.03Conform to the following Section and Subsections:
Crushed aggregate
Geosynthetic material Select borrow 703.06 714 704.02 Soil and soil- aggregate materials 704.01 Water for construction 725.01(c)
Construction Requirements
204.04Preparation for Roadway Excavation and Embankment Construction . Clear the area of vegetation and obstructions according to Section 201 and 203. Road pioneering may proceed concurrently with excavation and embankment. Maintain drainage during pioneering operations.
204.05Conserved Topsoil . Conserve topsoil from roadway excavation and embankment foundation areas. Stockpile conserved topsoil in low windrows less than 4 feet i n height and located immediately beyond the rounding limits of cut and embankment slopes or in other approved locations. Separate topsoil from other excavated material. Do not drive or park on conserved topsoil. Place conserved t opsoil on completed slopes according to Section 624 within 1 year of stockpiling.
204.06Roadway Excavation. Excavate as follows:
(a)Rock cuts. Verify the top portion of the rock cuts during pioneer access or initial excavation. Construct the final soil cut before starting drilling for rock blasting or other rock excavation methods unless approved. Blast rock according to Section 205. Excavate rock cuts to 6 inches below subgrade within the roadbed limits. Backfill to subgrade with select borrow. Compact the material according to Subsection 204.11.
(b)Earth cuts Scarify earth cuts to 6 inches below subgrade within the roadbed limits. Compact the scarified material according to Subsection 204.11 . Conserve 6- inch minus material from the roadway excavation to use for finishing the roadbed. Dispose of unsuitable or excess excavation material according to Subsection 204.14 . Replace shortage of suitable material caused by premature disposal of roadway excavation. At the end of each day’s operations, shape to drain and compact the work area to a uniform cross -section.
204.07Subexcavation. Excavate material to the required limits. Dispose of unsuitable material according to Subsection 204.14. Take measurements before backfilling. Backfill with select borrow in horizon tal lifts no more than 12 inches in compacted thickness and compact according to Subsection 204.11. Place earthwork geosynthetics according to Section 207 as shown in the plans . Place crushed aggregate according to Section 302 as shown in the plans. Prevent unsuitable material from mixing with backfill.
204.08Borrow Excavation. Use suitable roadway excavation in embankment construction. Do not use borrow excavation if it results in excess roadway excavation. Deduct excess borrow excavation from the total borrow excavation quantity. Obtain borrow source approval according to Subsection 105.02. Develop and restore borrow sources according to Subsections 105.03 and 105.06. Do not excavate beyond the establishe d limits. If applicable, shape the borrow source to allow accurate measurements when excavation is complete.
204.09Preparing Foundation for Embankment Construction. Prepare foundation for embankment construction as follows:
(a)Embankment over natural grou nd. Remove topsoil and break up the ground surface to a minimum depth of 6 inches by plowing or scarifying. Compact the ground surface according to Subsection 204.11.
(b)Embankment over an existing asphalt, concrete, or gravel road surface. Scarify gravel roads to a minimum depth of 6 inches. Scarify or pulverize asphalt and concrete roads to 6 inches below the pavement. Reduce particles to a maximum size of 6 inches and produce a uniform material. Compact the surface according to Subsection 204.11. (c) Embankment across ground that cannot support equipment. Dump successive loads of embankment material in a uniformly distributed lift to construct the lower portion of the embankment. Limit the lift thickness to the minimum depth necessary to support the equipment.
(d)Embankment on an existing slope steeper than 1V:3H. Cut horizontal steps in the existing slope to a sufficient width to accommodate placement and compaction operations and equipment. Step t he slope as the embankment is placed and compacted in lifts. Start each step at the intersection of the original ground and the vertical cut of the previous step.
204.10Embankment Construction. Incorporate only suitable roadway excavation material into t he embankment. When the supply of suitable roadway excavation is exhausted, provide unclassified borrow to complete the embankment. Construct embankments as follows:
(a)General. At the end of each day’s operations, shape to drain away from the embankment and compact the embankment surface to a uniform cross -section. Eliminate ruts and low spots that could hold water. During all stages of construction, route and distribute hauling and leveling equipment over the width and length of each lift of material. Compact embankment side slopes with a tamping foot roller, by walking with a dozer, or by over- building the fill and then removing excess material to the final slope line. For slopes 1V:1¾H or steeper, compact the slopes as embankment construction progresses.
(b)Embankment within the roadway prism. Place embankment material in horizontal lifts no more than 12 inches in compacted thickness. Construct the top 12 inches of the embankment using 6 -inch minus material. Incorporate oversize boulders or rock fragments into the lower lifts by reducing them in size or placing them individually as required below. Compact each lift according to Subsection 204.11 before placing the next lift. Material composed pred ominately of boulders or rock fragments too large for 12 -inch lifts may be placed in lifts up to 24 inches thick. Incorporate oversize boulders or rock fragments into the 24 -inch lift by reducing them in size or placing individual rock fragments and boulders greater than 24 inches in diameter as follows:
(1)Reduce rock to less than 48 inches in the largest dimension.
(2)Distribute rock within the embankment to prevent voids.
(3)Place lifts of embankment material around each rock to a depth not greater than allowed b y Subsection 204.10(b) . Fill voids between rocks.
(4)Compact each lift according to Subsection 204.11(a) before placing the next lift.
(c)Embankment outside of roadway prism. If placing embankment outside the staked roadway prism, place material in horizontal lifts less than 24 inches in compacted thickness. Compact each lift according to Subsection 204.11.
204.11Compaction . For compaction, use AASHTO T 27 to determine the quantity of material retained on a No. 4 sieve. Compact each lift of material to a firm and stable condition and until there is no visible evidence of further consolidation or deflection. Compact as follows :
(a)More than 80 percent retained on a No. 4 sieve. Compact as follows:
(1)Adjust the moisture content to a level suitable for compaction.
(2)Fill the voids around rock with earth or other fine material as practical.
(3)Use compression -type rollers at speeds less tha n 6 feet per second and vibratory rollers at speeds less than 3 feet per second.
(4)Compact each lift of material full width with one of the following:
(a)4 roller passes of a vibratory roller with a minimum centrifugal force of 40,000 pounds impact per vibration and a minimum frequency of 1000 vibrations per minute; (b) 8 roller passes of a 20 -ton compression- type roller; or
(c)8 roller passes of a vibratory roller with a minimum centrifugal force of 30,000 pounds impact per vibration and a minimum frequency of 1000 vibrations per minute.
(5)Increase the compactive effort for lifts deeper than 12 inches as follows:
(a)For each additional 6 inches or fraction thereof, increase the number of roller passes in Subsection 204.11(a)(4)(a) , by 4 passes; or
(b)For each additional 6 inches or fraction thereof, increase the number of roller passes in Subsection 204.11(a) (4)(b) and (c) , by 8 passes.
(b)50 to 80 percent retained on a No. 4 sieve. Classify the material according to AASHTO M 145. Adjust the moisture content of material classified A -1 through A -5 to a moisture content suitable for compaction. Adjust the moisture content of material classified A -6 and A -7 to within 2 percent of the optimum moisture content. Use AASHTO T 99 to determine the optimum moisture content of the portion of the material passing a No. 4 sieve. Multiply this number by the percentage of material passing a No. 4 sieve and add 2 percent to determine the optimum moisture content of the material. Use nonvibratory rollers at speeds less than 6 feet per second and vibratory rollers at speeds less than 3 feet per second . Compact each lift of material full width according to Subsection 204.11(a) .
(c)Less than 50 percent retained on a No. 4 sieve. Classify the material according to AASHTO M 145. For material classified A -1 or A -2-4, determine the m aximum density according to AASHTO T 180, Method D. For other material classifications, determine the optimum moisture content and maximum density according to AASHTO T 99, Method C. For material with more than 30 percent retained on the ¾-inch sieve, compact according to Subsection 204.11(a) . Adjust the moisture content of material classified A -1 through A -5 to a moisture content suitable for compaction. Adjust the moisture content of material classified A -6 and A -7 to within 2 percent of the optimum moisture content. Use compression -type or vibratory rollers. Compact each lift of material full width to at least 95 percent of the maximum density. Determine the in -place density and moisture content according to AASHTO T 310 or other approved test procedures.
204.12Ditches . Slope, grade, and shape ditches. Remove projecting roots, stumps, rock, and similar matter. Maintain ditches in an open condition and without debris. Form furrow ditches by plowing or using other approved methods to produce a continuous furrow. Place excavated material on the downhill side so the bottom of the ditch is approximately 18 inches below the crest of the loose material. Clean the ditch using a hand shovel or other suitable method. Shape to provide drainage without overflow.
204.13Sloping, Shaping, and Finishing. Complete slopes, ditches, culverts, riprap, and other underground minor structures before placing aggregate courses. Slope, shape, and finish as follows:
(a)Sloping. Leave earth slopes with uniform roughened surfaces, except as described in Subsection 204.13(b) , with no noticeable break as viewed from the road. Except in solid rock, round tops and bottoms of slopes including the slopes of drainage ditches. Round material overlaying solid rock to the extent practical. Remove loose or unstable rocks and dress all rock slopes as the excavation process progresses and slopes are still accessible to the equipment. Do not round slopes in wetlands or other sensitive areas. Do not place topsoil or mulch on slopes until approved. If a shallow landslide occurs on a cut or embankment slope, remove or replace the material and repair or restore damage to the work. Bench or key the slope to stabilize the sli de. Reshape the cut or embankment slope to an acceptable condition.
(b)Shaping. Shape the subgrade to a smooth surface and to the cross -section required. Shape slopes to gradually transition into slope adjustments without noticeable breaks. At the ends of cut s and at intersections of cuts and embankments, adjust slopes in the horizontal and vertical planes to blend into each other or into the natural ground.
(c)Finishing. Remove material larger than 6 inches from the top 6 inches of the roadbed. Remove unsuitable material from the roadbed and replace it with suitable material. Finish roadbeds and ditch cross -sections to within ±0.10 foot of the design or staked line and grade. Maintain proper ditch drainage.
204.14Disposal of Unsuitable or Excess Materi al. Dispose of unsuitable or excess material according to Subsection 203.07. If there is a pay item for waste, shape and compact the waste material in i ts final location. Do not mix clearing or other material not subject to payment with the waste material.
204.15Acceptance. See Table 204-1 for sampling, testing, and acceptance requirements. Material for embankment will be evalu ated under Subsections 106.02 and 106.04. Excavation and embankment construction will be evaluated under Subsections 106.02 and 106.04. Subexcavation will be evaluated under Subsections 106.02 and 106.04. Clearing will be evaluated under Section 201. Crushed aggregate will be evaluated under Section 302. Earthwork geosynthetics will be evaluated under Section 207. Placing conserved topsoil will be evaluated under Section 624 . Removal of obstructions will be evaluated under Section 203. Rock blasting will be evaluated under Section 205.
Measurement
204.16Measure the Section 204 pay items listed in the bid schedule according to Subsection 109.02 and the following as applicable:
(a)Roadway excavation. Measure roadway excavation in its original position as foll ows:
(1)Include the following volumes in roadway excavation:
(a)Roadway prism excavation. Use the design volume. The design volume is defined as the bid schedule quantity less any allowance, as shown in the summary of quantities sheet in the plans. This volume i s subject to adjustments resulting from changes to slope stakes according to Subsection 152.05(d) ;
(b)Rock material excavated and removed from below subgrade in cut sections;
(c)Unsuitable material below subgrade and unsuitable material beneath embankment areas, when a pay item for subexcavation is not listed in the bid schedule;
(d)Ditches, except furrow ditches measured under a separate pay item;
(e)Conserved topsoil stripped from cut s;
(f)Borrow material used in the work when a pay item for borrow is not listed in the bid schedule;
(g)Loose scattered rocks removed and placed as required within the roadway;
(h)Conserved material taken from pre -existing stockpiles and used in Section 204 work, except topsoil measured under Section 624; and
(i)Shallow landslide material not attributable to the Contractor’s method of operation.
(2)Do not include the following in roadway excavation:
(a)Overbur den and other spoil material from borrow sources;
(b)Overbreakage from the backslope in rock excavation;
(c)Water or other liquid material;
(d)Material used for purposes other than required;
(e)Roadbed material scarified in place and not removed;
(f)Material excavated wh ile rounding cut slopes;
(g)Preparing foundations for embankment construction;
(h)Conserved topsoil stripped from fill;
(i)Material excavated while benching for embankments;
(j)Shallow landslide material attributable to the Contractor’s method of operation;
(k)Conserved material taken from stockpiles constructed at the option of the Contractor;
(l)Material excavated outside the established slope limits;
(m)Pioneering for temporary roads outside of the proposed roadway prism; and
(n)Material removed during sloping, shaping, and finishing of rock slope excavations.
(3)If both roadway excavation and embankment construction pay items are listed in the bid schedule, measure roadway excavation only for the following:
(a)Unsuitable material below subgrade in cuts and unsuitable material beneath embankment areas if a pay item for subexcavation is not listed in the bid schedule;
(b)Shallow landslide material not attributable to the Contractor’s method of operations; and
(c)Drainage ditches, channel changes, and diversion ditches.
(b)Unclassified borrow and select borrow. When measuring by the cubic yard, measure in its final position. Measure borrow only after suitable roadway excavation is depleted.
(c)Embankment construction. Measure embankment construction in its final position. Do not make deductions from the embankment construction quantity for the volume of minor structures.
(1)Include the following volumes in embankment construction:
(a)Roadway prism embankments;
(b)Material used to backfill holes, pits, and other depressions;
(c)Material used to restore obliterated roadbeds to original contours; and
(d)Material used for dikes, ramps, mounds, and berms.
(2)Do not include the following in embankment construction:
(a)Preparing foundations for embankment construction;
(b)Adjustments for subside nce or settlement of the embankment or of the foundation on which the embankment is placed;
(c)Material used to round fill slopes; and
(d)Material used to backfill subexcavated areas.
(d)Rounding cut slopes. Measure rounding cut slopes horizontally along the center line of the roadway. (e) Waste. Measure waste by the cubic yard in its final position. Take initial cross -sections of the ground surface after stripping overburden. Upon completion of the waste placement, retake cross-sections before replacing overburden.
(f)Sube xcavation. Measure subexcavation by the cubic yard in its original position.
Payment
204.17The accepted quantities will be paid at the contract price per unit of measurement for the Section 204 pay items listed in the bid schedule. Payment will be full compensation for the work prescribed in this Section. See Subsection 109.05 . Table 204-1 Sampling, Testing, and Acceptance Requirements
Material or
Product
(Subsection) Type of
Acceptance
(Subsection) Characteristic Category Test Methods
Specifications Sampling
Frequency Point of
Sampling Split
Sample Reporting
Time Remarks
Source
Unclassified
borrow (704.01 ) Measured & tested for conformance (106.04 & 105) Classification(1) – AASHTO M 145 1 per soil type & source of material Source of material Yes Before using in work –
Select borrow
(704.02) Measured & tested for conformance (106.04 & 105) Classification(1) – AASHTO M 145 1 per soil type & source of material Source of material Yes Before using in work – Gradation – AASHTO T 27 & T 11 " " " " – Liquid limit – AASHTO R 58 & T 89, Method A " " " " –
Production
Unclassified
borrow (704.01 ) Measured & tested for conformance (106.04 ) Moisture - density – AASHTO T 180, Method D(2) or T 99, Method C(2) 1 per soil type but not less than 1 per each 13,000 yd3 Processed material Yes Before using in work – Density – AASHTO T 310 or other approved procedures 1 per 3500 yd2 but not less than 1 per lift In-place No Before placement of next lift – Table 204-1 (continued) Sampling, Testing, and Acceptance Requirements
Material or
Product
(Subsection) Type of
Acceptance
(Subsection) Characteristic Category Test Methods
Specifications Sampling
Frequency Point of
Sampling Split
Sample Reporting
Time Remarks
Production (continued)
Select
borrow (704.02 ) Measured & tested for conformance (106.04 ) Classification – AASHTO M 145 1 per soil type but not less than 1 per each day of production Processed material Yes Before using in work – Gradation – AASHTO T 27 & T 11 " " " " – Liquid limit – AASHTO R 58 & T 89, Method A " " " " –
Moisture -
density – AASHTO T 180, Method D(2) or T 99, Method C(2) 1 per soil type but not less than 1 per each 13,000 yd3 " " " – Density – AASHTO T 310 or other approved procedures 1 per 3500 yd2 but not less than 1 per lift In-place No Before placement of next lift – Table 204- 1 (continued) Sampling, Testing, and Acceptance Requirements
Material or
Product
(Subsection) Type of
Acceptance
(Subsection) Characteristic Category Test Methods
Specifications Sampling
Frequency Point of
Sampling Split
Sample Reporting
Time Remarks
Production (continued)
Earth
embankment (204.11 ) Measured & tested for conformance (106.04 ) Classification – AASHTO M 145 1 per soil type Source of material Yes Before using in work –
Moisture -
density – AASHTO T 180, Method D(2) or T 99, Method C(2) 1 per soil type but not less than 1 per each 13,000 yd3 " " " – Density – AASHTO T 310 or other approved procedures 1 per 3500 yd2 but not less than 1 per lift In-place No Before placement of next lift –
Top of
subgrade (204.11 ) " Density – AASHTO T 310 or other approved procedures 1 per 2500 yd2 but not less than 1 per lift In-place No Before placement of next lift –
Finished Product
Roadbed
(204.13) Measured & tested for conformance (106.04) Final line & grade – Field measured As directed As directed No Before placement of next lift –
(1)Not required if using Government- furnished source.
(2)At least 5 points per proctor.