STANDARD SPECIFICATIONS FOR CONSTRUCTION OF ROADS AND BRIDGES ON FEDERAL HIGHWAY PROJECTS (FP-14) - page 4

 

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STANDARD SPECIFICATIONS FOR CONSTRUCTION OF ROADS AND BRIDGES ON FEDERAL HIGHWAY PROJECTS (FP-14) - page 4

 

 

Section 204
(3) Place layers of embankment material around each rock to a depth not greater than that
permitted by Subsection 204.10(b). Fill voids between rocks; and
(4) Compact each layer according to Subsection 204.11(a) before placing the next layer.
(c) Embankment outside of roadway prism. When placing embankment outside the staked roadway
prism, place material in horizontal layers not exceeding 24 inches (600 millimeters) in compacted
thickness. Compact each layer according to Subsection 204.11.
204.11 Compaction. For compaction, use AASHTO T 27 to determine the quantity of material retained
on a No. 4 (4.75-millimeter) sieve. Compact as follows:
(a) More than 80 percent retained on a No. 4 (4.75-millimeter) sieve. Adjust the moisture content
to a level suitable for compaction. Fill the interstices around rock with earth or other fine material as
practical. Use compression-type rollers at speeds less than 6 feet (1.8 meters) per second and vibratory
rollers at speeds less than 3 feet (1 meter) per second. Compact each layer of material full width with
one of the following and until there is no visible evidence of further consolidation:
(1) Four roller passes of a vibratory roller having a minimum dynamic force of 40,000 pounds
(180 kilonewtons) impact per vibration and a minimum frequency of 1000 vibrations per minute;
(2) Eight roller passes of a 20-ton (20-metric ton) compression-type roller; or
(3) Eight roller passes of a vibratory roller having a minimum dynamic force of 30,000 pounds
(130 kilonewtons) impact per vibration and a minimum frequency of 1000 vibrations per minute.
Increase the compactive effort for layers deeper than 12 inches (300 millimeters) as follows:
For each additional 6 inches (150 millimeters) or fraction thereof, increase the number of
roller passes in Subsection 204.11(a)(1), by four passes; or
For each additional 6 inches (150 millimeters) or fraction thereof, increase the number of
roller passes in Subsection 204.11(a)(2) and (3), by eight passes.
(b) 50 to 80 percent retained on a No. 4 (4.75-millimeter) 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 (4.75-millimeter) sieve. Multiply this
number by the percentage of material passing a No. 4 (4.75-millimeter) sieve, and add 2 percent to
determine the optimum moisture content of the material.
Use nonvibratory rollers at speeds less than 6 feet (1.8 meters) per second and vibratory rollers at
speeds less than 3 feet(1 meter) per second. Compact each layer of material full width according to
Subsection 204.11(a).
(c) Less than 50 percent retained on a No. 4 (4.75-millimeter) sieve. Classify the material according
to AASHTO M 145. For material classified A-1 or A-2-4, determine the maximum 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.
105
Section 204
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 layer 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. When required, use AASHTO T 224 to correct for
coarse particles.
204.12 Ditches. Slope, grade, and shape ditches. Remove projecting roots, stumps, rock, or similar matter.
Maintain ditches in an open condition and without sticks, and other debris.
Form furrow ditches by plowing or using other acceptable methods to produce a continuous furrow. Place
excavated material on the downhill side so the bottom of the ditch is approximately
18 inches
(450 millimeters) below the crest of the loose material. Clean the ditch using a hand shovel or other
suitable method. Shape to provide drainage without overflow.
204.13 Sloping, 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. Scale rock slopes.
If a slide or slipout 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 slide. Reshape the cut or
embankment slope to an acceptable condition.
(b) Stepped slopes. Where required, construct steps on slopes of 1⅓V:1H to 1V:2H. Construct the
steps approximately 18 inches (450 millimeters) high. Blend the steps into natural ground at the end of
the cut. If the slope contains non-rippable rock outcrops, blend steps into the rock. Remove loose
material found in transitional area. Except for removing large rocks that may fall, scaling stepped
slopes is not required.
(c) 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 cuts 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.
(d) Finishing. Remove material larger than
6 inches
(150 millimeters) from the top
6 inches
(150 millimeters) of the roadbed. Remove unsuitable material from the roadbed, and replace it with
suitable material. Finish roadbeds that are compacted according to Subsection 204.11(b) and (c) to
within ±0.05 foot (±15 millimeters) of the staked line and grade. Finish roadbeds that are compacted
according to Subsection 204.11(a) to within ±0.10 foot (±30 millimeters) of the staked line and grade.
Finish ditch cross-sections to within ±0.10 feet (±30 millimeters) of the staked line and grade.
Maintain proper ditch drainage.
204.14 Disposal of Unsuitable or Excess Material. Dispose of unsuitable or excess material according to
Subsection 203.05(a).
106
Section 204
When there is a pay item for waste, shape and compact the waste material in its final location. Do not mix
clearing or other material not subject to payment with the waste material.
204.15 Acceptance. See Table 204-1 for sampling, testing, and acceptance requirements.
Material for embankment and conserved topsoil will be evaluated 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.
Measurement
204.16 Measure 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 follows:
(1) Include the following volumes in roadway excavation:
(a) Roadway prism excavation;
(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;
(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) Slide and slipout material not attributable to the Contractor's method of operation.
(2) Do not include the following in roadway excavation:
(a) Overburden 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 when stepping cut slopes;
(g) Material excavated when rounding cut slopes;
107
Section 204
(h) Preparing foundations for embankment construction;
(i) Material excavated when benching for embankments;
(j) Slide or slipout 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; and
(m) Road pioneering for the convenience of the Contractor.
(3) When 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 when a pay item for subexcavation is not listed in the bid schedule;
(b) Slide and slipout material not attributable to the Contractor’s method of operations; and
(c) Drainage ditches, channel changes, and diversion ditches.
(b) Unclassified borrow, select borrow, and topping. When measuring by the cubic yard (cubic
meter) measure in its original position. If borrow excavation is measured by the cubic yard (cubic
meter) in-place, take initial cross-sections of the ground surface after stripping overburden. Upon
completion of excavation and after the borrow source waste material is returned to the source, retake
cross-sections before replacing the overburden.
Do not measure borrow excavation until 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 embankments;
(b) Material used to backfill subexcavated areas, 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 subsidence or settlement of the embankment or of the foundation on
which the embankment is placed; and
(c) Material used to round fill slopes.
(d) Rounding cut slopes. Measure rounding cut slopes horizontally along the centerline of the
roadway.
108
Section 204
(e) Waste. Measure waste by the cubic yard
(cubic meter) in its final position. Take initial
cross-sections of the ground surface after stripping over-burden. Upon completion of the waste
placement, retake cross-sections before replacing overburden.
(f) Slope scaling. Measure slope scaling by the cubic yard (cubic meter) in the hauling vehicle.
(g) Subexcavation. Measure subexcavation by the cubic yard (cubic meter) in its original position.
Payment
204.17 The 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.
109
Section 204
Table 204-1
Sampling, Testing, and Acceptance Requirements
Material or
Type of
Characteristic
Category
Test Methods
Sampling
Point of
Split
Reporting
Product
Acceptance
Specifications
Frequency
Sampling
Sample
Time
(Subsection)
(Subsection)
Source
Topping
Measured and
Classification(1)
-
AASHTO
1 per
Source of
Yes
Before
(704.05)
tested for
M 145
soil type
material
using in
conformance
and
work
(106.04 & 105)
source of
material
Unclassified
"
"
-
"
"
"
"
"
borrow
(704.06)
Select borrow
"
"
-
"
"
"
"
"
(704.07)
Gradation
-
AASHTO
"
"
"
"
T 27 & T 11
Liquid limit
-
AASHTO
"
"
"
"
R 58 & T 89,
Method A
110
Section 204
Table 204-1 (continued)
Sampling, Testing, and Acceptance Requirements
Material or
Type of
Characteristic
Category
Test Methods
Sampling
Point of
Split
Reporting
Product
Acceptance
Specifications
Frequency
Sampling
Sample
Time
(Subsection)
(Subsection)
Production
Topping
Measured and
Moisture-
-
AASHTO
1 per
Processed
Yes
Before
(704.05)
tested for
density
T 180, Method D(2)
soil type,
material
using in
conformance
or
but not less than
work
(106.04)
T 99, Method C(2)
1 per each
13,000 yd3
(10,000 m3)
Density
-
AASHTO
1 per
In-place
No
Before
T 310 or
3500 yd2
placement
other approved
(3000 m2),
of
procedures
but not less
next layer
than 1 per layer
Unclassified
"
Moisture-
-
AASHTO
1 per
Processed
Yes
Before
borrow
density
T 180, Method D(2)
soil type,
material
using in
(704.06)
or
but not less than
work
T 99, Method C(2)
1 per each
13,000 yd3
(10,000 m3)
Density
-
AASHTO
1 per
In-place
No
Before
T 310 or
3500 yd2
placement
other approved
(3000 m2),
of
procedures
but not less
next layer
than 1 per layer
111
Section 204
Table 204-1 (continued)
Sampling, Testing, and Acceptance Requirements
Material or
Type of
Characteristic
Category
Test Methods
Sampling
Point of
Split
Reporting
Product
Acceptance
Specifications
Frequency
Sampling
Sample
Time
(Subsection)
(Subsection)
Production (continued)
Select
Measured and
Classification
-
AASHTO
1 per
Processed
Yes
Before
borrow
tested for
M 145
soil type,
material
using in
(704.07)
conformance
but not less
work
(106.04)
than 1 for
each day of
production
Gradation
-
AASHTO
"
"
"
"
T 27 & T 11
Liquid limit
-
AASHTO
"
"
"
"
R 58 & T 89,
Method A
Moisture-
-
AASHTO
1 per
"
"
"
density
T 180, Method D(2)
soil type,
or
but not less than
T 99, Method C(2)
1 per each
13,000 yd3
(10,000 m3)
Density
-
AASHTO
1 per
In-place
No
Before
T 310 or
3500 yd2
placement
other approved
(3000 m2),
of
procedures
but not less
next layer
than 1 per layer
112
Section 204
Table 204-1 (continued)
Sampling, Testing, and Acceptance Requirements
Material or
Type of
Characteristic
Category
Test Methods
Sampling
Point of
Split
Reporting
Product
Acceptance
Specifications
Frequency
Sampling
Sample
Time
(Subsection)
(Subsection)
Production (continued)
Earth
Measured and
Classification
-
AASHTO
1 per
Source of
Yes
Before
embankment
tested for
M 145
soil type
material
using in
(204.11)
conformance
work
(106.04)
Moisture-
-
AASHTO
1 per
"
"
"
density
T 180, Method D(2)
soil type,
or
but not less than
T 99, Method C(2)
1 per each
13,000 yd3
(10,000 m3)
Density
-
AASHTO
1 per
In-place
No
Before
T 310 or
3500 yd2
placement
other approved
(3000 m2),
of
procedures
but not less than
next layer
1 per layer
Top of
"
Density
-
AASHTO
1 per
In-place
No
Before
subgrade
T 310 or
2500 yd2
placement
(204.11)
other approved
(2000 m2),
of
procedures
but not less than
next layer
1 per layer
Finished Product
Roadbed
Measured and
Final
-
Field measured
Determined
Determined
No
Before
(204.13)
tested for
placement
line & grade
by the CO
by the CO
conformance
of
(106.04)
next layer
(1) Not required when using Government-provided source.
(2) Minimum 5 points per proctor.
113
Section 205
Section 205. — ROCK BLASTING
Description
205.01 This work consists of rock fragmentation blasting using production and controlled blasting
techniques to construct engineered rock cuts.
205.02 Definitions.
(a) Production blasting. Blasting using widely spaced blast holes that typically contain larger
explosive charges to expedite movement and fragmentation for rock removal.
(b) Controlled blasting. Blasting that includes presplit blasting and cushion blasting hole
techniques. Controlled blasting uses closely-spaced and carefully aligned blast holes that typically
contain lighter charges than production holes to produce stable, aesthetically pleasing rock faces
with minimal blast damage. Controlled blast holes are the first row of blast holes, normally located
within 24 inches (600 millimeters) of the top of the staked slope.
(1) Presplit blasting. Presplit blasting detonates closely spaced backslope holes before drilling
for production blasting or before detonating the production blasting holes to produce a highly
controlled, smooth cut face.
(2) Cushion blasting. Cushion blasting is similar to presplitting, except that the detonation of the
cushion holes along the backslope is detonated immediately after the detonation of the
production and buffer holes, generally resulting in a more natural cut face appearance.
Construction Requirements
205.03 Regulations. Comply with Federal, state, and local regulations for the purchase, transportation,
storage, and use of explosive material. Federal regulations include the following:
(a) Safety and health. OSHA, 29 CFR Part 1926, Subpart U.
(b) Storage, security, and accountability. Bureau of Alcohol, Tobacco, and Firearms (BATF),
27 CFR Part 555, Commerce in Explosives.
(c) Shipment. DOT, 49 CFR Parts 171-179, 390-397.
(d) National Park Service. For projects in National Park Service lands, comply with National Park
Service Director’s Order No. 65, Explosives Use and Blasting Safety.
205.04 Qualifications. Submit the following for approval at least 14 days before drilling and blasting
operations begin:
(a) Blaster-in-charge. Furnish an individual who can directly supervise the drilling and blasting
crew during drilling, loading, and detonation of charges. Include the following:
(1) Name of blaster-in-charge;
114
Section 205
(2) A résumé showing at least 5 years’ experience as a blaster-in-charge on projects with similar
work;
(3) Copy of a valid blaster license accepted by the state where the project is located for the type
of blasting required; and
(4) Five references with knowledge of qualifications and reliability. Include name, relationship,
and current telephone number for each reference.
(b) Blasting crew personnel. Names of personnel and evidence they have completed at least
24 hours of blasting safety training in the last
5 years’ or have at least
2 years’ of blasting
experience.
(c) Drillers. Names and evidence they are proficient in drilling methods required to perform the work.
(d) Vibration specialist. Name and résumé showing at least 5 years’ experience as a vibration
specialist on projects with similar work.
205.05 Blasting Plans. Submit proof of applicable permits, licenses, and a general blasting plan signed by
the blaster-in-charge at least 14 days before drilling and blasting operations. Blasting plans are not
required for boulder reduction blasts (mudcapping or blockholing).
(a) General blasting plan. Submit a general blasting plan for review and approval by the CO. Include
the following:
(1) Procedures and safety precautions for transporting, handling, storing, loading, and detonating
explosives, conducting pre- and post-blast surveys, monitoring blasts, managing misfires, and
removing and disposing of excess explosives.
(2) Explosives transportation and storage plan, including:
(a) Name, address, and telephone number of explosives suppliers;
(b) Description and license number of explosives transport vehicles, routes to be traveled,
proposed hours of travel, and driver qualifications;
(c) Magazine and day-box locations;
(d) Explosives and accessories inventory system; and
(e) Contact information for the person responsible for security of project blasting material
and supplies.
(3) Area security plan including explosives and general site security, methods of site
communication, pre- and post-blast signage and audible signaling systems, road closure
requirements, and pre-blast notification for affected agencies or entities.
(4) Manufacturer’s MSDS and product data sheets for proposed explosives, primers, initiators,
and related blasting devices and accessories.
(5) Excavation plans and equipment lists for pre-blast scaling and pioneered access roads, and
benches for drilling and blasting operations.
115
Section 205
(6) Typical plan and section views for both production and controlled blasting, including
stationing intended for each typical plan, maximum blast length, free face, burden, hole spacing,
hole inclination, hole depth, hole diameter, stemming depth, subdrill depth, powder factor,
charge per delay, initiation method and sequence, and delay times.
(7) Methods for limiting dust and noise.
(8) Fire watch plan including number of post-blast observers and duration of the fire watch.
(9) Contingency plan for blast flyrock containment, including the names and qualifications of
those responsible for preparing containment system designs.
Do not deliver explosives to the project until the general blasting plan is accepted. Submit revisions
and updates within 48 hours of changes in the above information.
(b) Site-specific blasting plans and general plan revisions and updates. Submit site-specific
blasting plans after approval of the general blasting plan or at times there is a change in drilling and
blasting methods provided in the general blasting plan. Allow 3 days for approval. Do not begin
drilling until the plan is approved. Include the following:
(1) Proposed excavation sequence;
(2) Station limits and plan view of the proposed blast, showing how the proposed blast fits into
the lift excavation sequence;
(3) Elevations of the tops and bottoms of each lift;
(4) Scaled drawings for each blast showing access, containment, plan and section views of drill
patterns, clearing limits, free face, burden, blast hole locations, blast hole spacing, subdrill
depths, lift height, blast hole diameters, and blast hole angles;
(5) Loading diagram for each blast showing powder factor, charge per delay, type and quantity
of explosives, primers, initiators, locations of decking, and range of stemming depths for
substantial variations within the drill pattern;
(6) Initiation method and sequence of blast holes for each blast. Include delay times, delay
system, and down hole firing times;
(7) Flyrock control measures;
(8) Estimated volume of in-place rock to be blasted. Include the total length of production and
controlled blast hole;
(9) Location and orientation of significant joints, fractures, faulting, bedding planes or other rock
mass structural features to be accounted for in the site-specific blasting plan; and
(10) Post-blast rockfall containment designs and procedures.
205.06 Pre-Blast Condition Survey and Vibration Monitoring and Control. The Contractor is
responsible for damage resulting from blast related ground vibrations and air-blast over-pressures.
Determine the need for vibration monitoring depending on soil and rock conditions, blasting parameters as
outlined in the blasting plan, and proximity of buildings, structures, utilities, and sensitive natural features
that may be subject to damage from ground vibrations or air-blasts. If vibration monitoring is required
conform to the following requirements:
116
Section 205
(a) If not specified in the contract, establish referenceable blasting criteria for buildings, structures,
utilities and natural features that conform to federal, state, or local regulations. Present blasting criteria
in terms of distance of the facility or feature from blasting, maximum allowable peak particle velocity
limits versus structure type, maximum allowable peak particle velocity versus peak frequency, and air
over-pressure structure damage limits.
(b) Conduct a pre-blast condition survey of nearby buildings, structures, utilities, and natural features
potentially damaged by blasting-related ground vibrations or air-blast. Document the natural frequency
of each affected structure or feature. Use a survey method acceptable to the Contractor’s insurance
company. Submit a copy of pre-blast condition survey records with the site-specific blasting plans for
CO review.
(c) Control ground vibrations and air-blast over-pressures with properly designed delay sequences and
maximum allowable charge weights per delay. Verify allowable charge weights per delay by
conducting representative trial blasts and measuring ground vibrations and air-blast over-pressure
levels. Conduct test blasts with blast plan modifications that limit ground vibrations and air-blast
over-pressures to levels that will not cause damage to nearby buildings, structures, utilities and natural
features as determined by the vibration specialist.
(d) When ground vibration or air-blast damage is possible, monitor each blast with digital recording
seismographs and air-blast monitoring equipment calibrated within the last year and approved by the
CO. Locate monitoring equipment as directed by the vibration specialist. Place at least three recording
stations between the blast area and closest susceptible structures, utilities, or natural features. Place at
least one station on the structure. For ground vibration monitoring, use seismographs capable of
recording particle velocity, displacement and acceleration for three mutually perpendicular
components of vibration. Use a seismograph with a lower linear response limit over the response
frequency range of not more than 2 hertz and upper limit not less than 50 hertz. Use sensors having
lower thresholds not higher than 0.005 inches (0.13 millimeters), 0.05 inches (1.3 millimeters) per
second, and 0.02g. Use seismographs capable of producing a permanent digital time history file for
each ground motion episode.
Ensure blasting operations incorporate collected data and findings from vibration monitoring by having the
vibration specialist interpret seismograph and air-blast records.
205.07 Test Blasting. Before beginning full-scale drilling and blasting, demonstrate adequacy of the
site-specific blasting plan by drilling, blasting, and excavating a test blast of up to 100 cubic yards
(75 cubic meters) with proposed containment measures in-place. Conduct the test at an approved
location within the planned excavation area.
A test blast is unacceptable when it results in oversized fragmentation, excessive or uncontrolled
flyrock, potentially damaging ground vibrations or air-blasts, unplanned overbreak, excessive damage to
the final rock face, or unwanted overhangs. When a test blast is unacceptable, revise the site-specific
blasting plan and conduct an additional test blasts until the combination of blast hole pattern spacing,
controlled blast hole alignment, and charges produce acceptable results.
205.08 Blasting. Use explosives and initiating devices less than
1-year old. Locate explosives
magazines at sites approved by the CO.
Inspect the pre-blast area and submit the proposed extent of pre-blast clearing and scaling for approval.
117
Section 205
Use angle- or fan-drilled holes as needed during initial pioneering operations to obtain the desired face.
Controlled blasting requirements are applicable to pioneering work.
Record and maintain a log of each blast hole drilled identifying the depth, color, and character of the
cuttings, penetration rate, hole collar location and hole orientation, and other pertinent information. Before
initiating the blast, prepare a blast plan map and submit it showing designated hole numbers along with
individual hole logs completed, dated and signed by the driller.
Ensure blast holes are free of obstructions for the entire depth before placing charges. Take necessary
precautions when placing charges so, caving of material from the walls of the holes and the hole collar will
not occur.
Mitigate uncontrolled gas pressure loss during blasting and excessive blast noise by stemming the upper
portion of blast holes with appropriate dry granular material passing the ½-inch (12.5-millimeter) sieve.
Do not stem holes with drill cuttings.
Blast according to the approved site-specific blasting plan. Use blasting mats, rockfall containment
systems, and other protective devices to prevent damage to surrounding features.
Stop drilling and blasting operations, and submit a revised site-specific blasting plan according to
Subsection 205.05(b), when the following occur:
Slopes are unstable;
Slopes exceed overbreak tolerances;
Unwanted overhangs, ridges, or ledges are created;
Excessive blast damage occurs;
Poor fragmentation results in oversize material requiring secondary blasting and rehandling;
Safety of the public is jeopardized;
Property or natural features are endangered;
Excessive or uncontrolled flyrock is generated;
Excessive ground vibration or air-blast over-pressures occurs where damage to buildings,
structures, utilities or natural features is possible; or
Desired slope or rock face conditions are not produced.
Remove or stabilize cut face rock that is loose, hanging, or potentially dangerous after each blast. Scale
by methods approved by the CO. Leave minor irregularities or surface variations in place if they do not
create a hazard. Excavate and remove material outside of the planned neat line slopes which is unstable
and constitutes a potential hazard. Do not drill the next lift until slope stabilization and blast cleanup
work is complete.
(a) Production blasting. When conducting cushion blasting or presplitting, drill a lighter-loaded
buffer row of production holes on a parallel plane adjacent to the controlled blast line to minimize
blast damage to the final slope.
118
Section 205
Drill production blast holes a maximum of 4 inches (100 millimeters) in diameter to a sufficient
depth such that unbroken rock does not extend above the finish surface. Drill production blast holes
to the design depth. If more than 5 percent of the production blast holes in a lift do not conform to
the design depth requirements, redrill the shallow holes to the proper. Except when subdrilling, do
not drill production blast holes, below the base plane of the controlled blast holes.
Drill production blast holes within two drill hole diameters of the planned collar location. If more
than 5 percent of the drill hole collars in a lift are out of tolerance, fill each hole outside of the
location tolerance with crushed stone and redrill at the proper.
Detonate production holes in a controlled delay sequence.
(b) Controlled blasting. Use angled or fan drilled holes for pioneering the tops of rock cuts and
preparing working platforms. Use equipment or methods approved by the CO for areas not accessible
to track drill equipment.
Before drilling, completely remove overburden, soil, and loose or decomposed rock along the top of
the excavation for a distance of at least 30 feet (9 meters) beyond the end of the production hole
drilling limits, or to the end of the cut.
Use controlled blasting to form the final cut face on rock cuts where the staked slope ratio is
1⅓V:1H or steeper and the slope height is more than 10 feet (3 meters) above the ditch grade.
Use drilling equipment that accurately controls the angle the drill as it enters the rock. Select a lift
height and conduct drilling operations so the blast hole spacing and down-hole alignment does not
vary more than 8 inches (200 millimeters) from the proposed spacing and alignment. If more than
5 percent of the holes exceed the variance, reduce the lift height and modify drilling operations until
the holes are within tolerance.
Drill holes a maximum of 3 inches (75 millimeters) in diameter and within 3 inches (75 millimeters)
of the staked collar location. Fill and redrill blast holes outside of the location tolerance when more
than 5 percent of the hole collars in a lift are outside of the location tolerance Use crushed stone to
fill the blast holes before redrilling. Drill the controlled blast hole line at least 30 feet (9 meters)
beyond loaded production holes or to the end of the cut.
Do not exceed 30 feet (9 meters) for bench height or drill hole length. Limit subdrilling of holes to
one-half of the hole spacing or 24 inches (600 millimeters) whichever is deeper.
Offset lifts up to 24 inches (600 millimeters) horizontally to allow for drill equipment clearance.
Remove benches resulting from the drilling offset.
Compensate for drift that may occur in the upper lifts. Adjust the drill inclination angle or the initial
drill collar location to obtain the required typical section. Limit drilling to one-half of the hole spacing
or 24 inches (600 millimeters) whichever is deeper.
Do not use bulk ammonium nitrate and fuel oil for controlled blasting. Only standard explosives
manufactured specifically for controlled blasting will be used in controlled blast holes, unless
approved by the CO.
119
Section 205
Maximum diameter of explosives used in controlled blast holes will be no greater than one-half the
diameter of the presplit hole.
(1) Presplitting. Do not presplit final slopes and rock faces. When presplitting is allowed in the
plans, either presplit along the slope face before drilling for production blasting or presplit the
slope face in conjunction with production blasting.
(2) Cushion blasting. Perform cushion blasting to produce rough, natural looking rock slopes. Use
the existing geologic structure to create rock surfaces, terraces, and ridges that blend with adjacent
undisturbed rock faces. Preserve existing rock outcrops to the extent practical to vary the cut face
slope, composition, color, and texture.
(3) Horizontal blasting. With CO approval only, use horizontal drill holes instead of or in
conjunction with vertical cushion blasting drill holes to produce natural looking rock slopes,
mitigate drill hole traces, assist pioneering access for drill bench excavation, or to excavate sliver
rock cuts where vertical drilling is not feasible.
When required, preserve or create soil pockets and ledges for revegetation. Locate, size, and shape
these features to replicate the vegetated areas on the undisturbed rock faces. Incorporate these
features into the site-specific blasting plans. Do not create features by overshooting or selectively
removing damaged rock.
205.09 Reporting.
(a) Post-blast. Prepare an post-blast report for blasts. Submit the report within 3 days following a blast
and before drilling for the next blast. Include the following:
(1) Results of the blast (overbreak, blast damage, noise levels, flyrock, drill trace retention,
fragmentation, material containment, material rehandling requirements, and misfires);
Submit proposed changes for future site-specific blasting plans that will produce acceptable results
if blasting objectives were not met. Submit proposed repairs or stabilization plans for unstable or
blast damaged backslopes;
(2) A detailed blasting plan amended to show significant changes in pattern, loading, or timing;
(3) Drilling logs for each hole completed (dated and signed by the driller) that identify the depth,
color, and character of the cuttings. Also include the penetration rate, hole collar location, hole
orientation, and conditions that adversely affected drilling or explosives loading operations;
(4) Depth measurements of production and controlled blast holes;
(5) A drawing or sketch showing the direction of blast, the face, or faces, hole numbers, and the
physical blast layout;
(6) Measurement of overbreak quantities following lift mucking;
(7) Date and time of loading and detonating the blast; and
(8) Name and signature of the blaster-in-charge.
(b) Vibration and air-blast reporting. Submit a vibration and air-blast report within 3 days of a blast
for review by the CO. Do not drill until directed by the CO. Include the following:
(1) Type of vibration or air-blast recording station used and instrument identification numbers;
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Section 205
(2) Name of vibration specialist observing the blast and interpreting vibration and air-blast data;
(3) Blast identification number and location of blast;
(4) Distance and direction of ground vibration and air-blast over-pressure recording stations from
the blast area;
(5) Type of material ground vibration recording stations were sitting on at the time of the blast;
(6) Maximum applicable charge weight per delay;
(7) Peak displacement, particle velocity and frequency recorded at each ground vibration sensor
location;
(8) Peak over-pressure recorded at each air-blast sensor location;
(9) Dated and signed copy of all instrument records;
(10) Post-blast condition survey noting changes from the pre-blast survey; and
(11) Comments on success of the blast in terms of adherence to established ground vibration or air-
blast criteria and management practices.
When failing to meet ground vibration and air-blast criteria and management objectives, submit
proposed changes to future site-specific blasting plans that will produce acceptable results.
(c) Close-out. Submit a written statement signed by the blaster-in-charge certifying:
(1) Blastholes loaded with explosive material have been either detonated or unloaded and
disposed of properly; and
(2) Blasting is complete and explosive material has been removed from the project site.
205.10 Acceptance. Material for rock blasting will be evaluated under Subsections 106.02 and 106.03.
Rock blasting will be evaluated under Subsections 106.02 and 106.04.
Measurement
205.11 Measure the Section 205 pay items listed in the bid schedule according to Subsection 109.02 and
the following as applicable:
When measuring controlled blasting by the square foot (square meter), measure the face blast as shown in
the blasting plan.
When measuring controlled blast holes by the linear foot (meter), measure the actual length of drilling
recorded in the post blast reports. Controlled blast hole includes the row of holes lying closest to the trim
line.
Do not measure presplit blast holes whose misalignment is more than 8 inches (200 millimeters.)
Do not measure production blast holes.
121
Section 205
Payment
205.12 The accepted quantities will be paid at the contract price per unit of measurement for the Section
205 pay items listed in the bid schedule. Payment will be full compensation for the work prescribed in this
Section. See Subsection 109.05.
122
Section 206.RESERVED
123
Section 207
Section 207. — EARTHWORK GEOSYNTHETICS
Description
207.01 This work consists of furnishing and installing geotextile in separation, stabilization, and filter
applications, geogrid in stabilization applications, and geomembrane in moisture barrier applications.
Geosynthethics are designated according to the tables in Section 714.
Material
207.02 Conform to the following Subsections:
Geomembrane
714.05
Geotextile
714.01
Stabilization geogrid
714.03
Construction Requirements
207.03 General. Identify, store, and handle geosynthetics according to ASTM D4873 and the
manufacturer’s recommendations. Elevate and protect geosynthetic rolls with a waterproof cover if stored
outdoors. Limit geosynthetics exposure to less than 10 days of ultraviolet radiation.
For seams sewn on-site, conform to the manufacturer’s recommendations. Obtain approval of the seam
before installation. Use thread consisting of high strength polypropylene or polyester. Do not use nylon
thread. Use thread that is resistant to ultraviolet radiation and a contrasting color to the geotextile.
Submit a seam assembly description and a sample of the sewn material at least 14 days before installation
when geosynthetic joints are sewn as follows:
(a) Assembly description. Include the seam type, seam allowance, stitch type, sewing thread tex ticket
numbers and types, stitch density, and stitch gauge.
(b) Sewn seam samples. Sew seam samples using the same equipment and procedures used to sew
production seams. Submit samples that have at least 6 feet (1.8 meters) of sewn seam and are at least
5 feet (1.5 meters) wide. If production seams are sewn in both the machine and cross-machine
directions, provide sewn seam samples that are oriented in both the machine and cross-machine
directions.
Replace or repair geosynthetic that is torn or punctured. Remove the damaged area and place a patch of the
same type of geosynthetic overlapping 36 inches (900 millimeters) beyond the damaged area or sew a
seam around the damaged area.
207.04 Geotextile and Geogrid Separation and Stabilization Applications.
(a) Surface preparation. Before placing the geotextile, geogrid, or both, prepare the surface as
follows:
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Section 207
(1) Existing ground. Cut trees and shrubs flush with the ground surface. Do not remove the
topsoil and vegetation mat. Clear the area of vegetation and obstructions according to Sections
201 and 203. Remove sharp objects and large rocks. Fill depressions or holes with suitable
material to provide a smooth surface.
(2) Subgrade. Prepare the subgrade according to Subsections 204.13(c) and (d).
(3) Subexcavation. Perform subexcavation according to Subsection 204.07.
(b) Geotextile or geogrid placement. Place geogrid on top of geotextile when both are shown at the
same elevation in the plans. Place the geosynthetic smooth, taut, and wrinkle free on the underlying
surface. Conform to curves. Overlap in the direction of construction. Overlap at least 24 inches
(600 millimeters) at the ends and sides of adjoining sheets or sew the joints according to the
manufacturer’s recommendations. Do not place longitudinal overlaps below anticipated wheel loads.
Hold the geosynthetic in place with pins, staples, or piles of cover material.
(c) Backfilling.
(1) First layer placement and compaction. End dump the backfill material onto the geotextile or
geogrid from the edge of the geosynthetic or from previously placed cover material. Do not operate
equipment directly on the geosynthetic. Spread the end-dumped pile of cover material maintaining
a 12 inch (300 millimeters) lift over the geosynthetic. Avoid sudden stops, starts, or turns of the
construction equipment. Fill ruts from construction equipment with additional cover material. Do
not blade material down to remove ruts. If rutting exceeds 3 inches (75 millimeters) during
placement, decrease the construction equipment size, decrease the equipment weight, or increase
the first lift thickness as directed by the CO.
Compact according to Subsection
204.11. Do not use sheepsfoot or studded compaction
equipment. Compact the cover material with pneumatic-tire or nonvibratory smooth drum rollers.
(2) Subsequent layer placement and compaction. Place subsequent layers according to
Subsection 204.10.
Compact according to Subsection 204.11. Vibratory rollers may be used unless pumping or
foundation failures occur. Repair damaged areas and then use only nonvibratory rollers.
207.05 Reinforcement Geotextile and Geogrid. See Section 261 for reinforcement geotextile and
geogrid placement.
207.06 Geotextile Filter Applications.
(a) Geotextile placement. For slope or wave protection, place the long dimension of the geotextile
down the slope. For stream bank protection, place the long dimension of the geotextile parallel to the
centerline of the channel.
Overlap or sow seams at the ends and sides of adjoining sheets.
(1) Overlapping. Overlap the uphill or upstream sheet over the downhill or downstream sheet. For
above water applications, overlap the geotextile at least
12 inches
(300 millimeters). For
underwater applications, overlap the geotextile at least 36 inches (900 millimeters).
125
Section 207
(2) Sewing. Sew the geotextile seam according to the manufacturer’s recommendations.
Offset end joints of adjacent sheets at least 5 feet (1.5 meters). Use key trenches or aprons at the crest
and toe of slopes to hold the geotextile in place. As an alternative use anchor pins, at least 18 inches
(450 millimeters) long and spaced at 36 inch (900 millimeters) centers to hold the geotextile sheets in
place.
(b) Backfilling. Place aggregate, slope protection, or riprap on the geotextile starting at the toe of the
slope and proceeding upward. Place riprap onto the geotextile from a height of less than 12 inches
(300 millimeters). Place slope protection rock or aggregate backfill onto the geotextile from a height
less than
36 inch
(900 millimeters). Do not allow stones weighing more than
100 pounds
(45 kilograms) to roll down the slope. In underwater applications, place the geotextile and cover
material in the same day.
207.07 Geomembrane Applications. Submit a geomembrane installation plan at least 10 days before
installing the geomembrane. Include a drawing of the panel layout identifying the location of seams.
Include a seam detail and a written description of the seaming procedure.
(a) Surface preparation. Provide a smooth, flat, firm, unyielding foundation for the geomembrane
with no sudden, sharp, or abrupt changes or break in grade. Remove rocks, stones, sticks, sharp
objects, and debris protruding more than ½ inch (13 millimeters) above the prepared surface.
(b) Geomembrane placement. Orient seams parallel to the line of maximum slope. Use sandbags or
piles of cover material to hold the geomembrane in place. Do not drive equipment directly on the
geomembrane.
(c) Backfilling. Place backfill material within the same work shift that the geomembrane is installed.
End dump backfill material onto the edge of previously placed cover material and roll it into place. Do
not push material along the geomembrane which can result in damage or wrinkling.
207.08 Acceptance. Geosynthetics will be evaluated under Subsection 106.03. Submit a production
certification with each shipment of geosynthetics.
Geosynthetic installation will be evaluated under Subsections 106.02 and 106.04.
Sewn joints will be evaluated under Subsection 106.02.
Measurement
207.09 Measure the Section 207 pay items listed in the bid schedule according to Subsection 109.02.
When measuring geosynthetics by the square yard (square meter), measure on the plane parallel to the
slope face.
Do not measure overlapping material.
126
Section 207
Payment
207.10 The accepted quantities will be paid at the contract price per unit of measurement for the Section
207 pay item listed in the bid schedule. Payment will be full compensation for the work prescribed in
this Section. See Subsection 109.05.
127
Section 208
Section 208. — STRUCTURE EXCAVATION AND BACKFILL
FOR SELECTED MAJOR STRUCTURES
Description
208.01 This work consists of excavating material for the construction of selected structures. This work
also includes preserving channels, shoring and bracing, constructing cofferdams, sealing foundations,
dewatering, preparing foundations, backfilling, and subsequent removal of safety features and cofferdams.
Material
208.02 Conform to the following Section and Subsections:
Foundation fill
704.01
Neat hydraulic cement grout
725.13(a)(2)
Structural backfill
704.04
Structural concrete
552
Construction Requirements
208.03 General. Follow OSHA safety regulations 29 CFR, Part 1926, Subpart P, Excavations for sloping
the sides of excavations, using shoring and bracing, and using other safety features. When sides of
excavations are sloped for safety considerations, submit one copy of the design that demonstrates
conformity with OSHA regulations. Where support systems, shield systems, or other protective systems
are to be used, design the shoring according to Section 562. Submit drawings and construction details
according to Subsection 104.03.
Clear the area of vegetation and obstructions according to Sections 201 and 203.
Request approval from the CO as to the character and suitability of the foundation material when the
excavation is complete. Provide a firm foundation of uniform density throughout its length and width.
Saw cut existing pavements or concrete structures adjacent to the area to be excavated that are designated
to remain.
Where necessary, blast rock according to Section 205.
Conserve suitable material for structural backfill from excavated material. Do not deposit excavated
material in or near a waterway. Do not stockpile excavated material or allow equipment closer than
24 inches (600 millimeters) from the edge of the excavation. Use suitable material in embankment
construction when approved. Dispose of unsuitable or excess material according to Subsection 204.14.
Remove safety features when no longer necessary. Remove shoring and bracing to at least 24 inches
(600 millimeters) below the surface of the finished ground.
128
Section 208
208.04 Channel Preservation. Perform work in or next to a running waterway as follows:
(a) Excavate and conserve material inside cofferdams, sheeting, or other separations (such as dikes or
sandbags);
(b) Do not disturb the natural bed of the waterway adjacent to the work; and
(c) Backfill the excavation to original ground-line with conserved material.
208.05 Cofferdams. Use cofferdams when excavating under water or when the excavation is affected by
groundwater.
Submit drawings showing proposed methods and construction details of cofferdams according to
Subsection 104.03 and Section 562. Design and construct cofferdams that conform to the following:
(a) Extend below the bottom of the footing;
(b) Brace to withstand pressure without buckling and secured in place to prevent tipping or movement;
(c) Construct watertight as practical;
(d) Provide sufficient clearance for the placement of forms and the inspection of their exteriors;
(e) Provide for dewatering;
(f) Protect fresh concrete from damage; and
(g) Prevent damage to the foundation by erosion.
Remove cofferdam material down to the natural bed of the waterway or to the top of seal, whichever is
lower. Remove cofferdam material outside the waterway to at least 24 inches (600 millimeters) below the
surface of the finished ground.
208.06 Foundation Seal. Seal the foundation area from water by placing seal concrete when the area
cannot be pumped reasonably free of water. Design seal concrete mix according to Subsection 552.03.
Furnish and place seal concrete according to Section 552. Maintain the water level inside the cofferdam at
the same level as the water outside the cofferdam while placing a foundation seal. Vent or port the
cofferdam at low water level when a foundation seal is placed in tidal water.
Do not dewater a concrete-sealed cofferdam until the seal concrete strength is sufficient to withstand the
hydrostatic pressure.
208.07 Dewatering. Remove water as necessary to perform the work. Dispose of water according to
Federal, state, and local regulations.
129
Section 208
208.08 Foundation Preparation. Prepare foundations as follows:
(a) Footings placed on bedrock. Excavate to the specified elevation. Clean the foundation surface of
deleterious material. Clean and grout seams and crevices. Place foundation fill to provide a level
bearing pad for footing.
(b) Footings placed on an excavated surface other than bedrock. Excavate material to foundation
grade and compact the foundation before footing is placed.
(c) Footings keyed into undisturbed material. Excavate the foundation to the limits of the footing
and compact the foundation. Where material does not stand vertically, fill the space between the limits
of the footing and the undisturbed material with concrete. Fill only to the top of the excavation if the
excavation is below the top of the footing. Concrete placed against steel sheet piles in cofferdams is
considered as being against undisturbed material.
(d) Unstable material below footing elevation. Excavate unstable material below foundation grade as
directed by the CO and backfill with foundation fill. Place foundation fill in horizontal layers that do
not exceed 6 inches (150 millimeters) in compacted thickness. Compact each layer according to
Subsection 208.10.
(e) Foundations using piles. Where foundation seals are required drive the piles before placing seal
concrete unless otherwise specified. Remove loose and displaced material and reshape the bottom of
the excavation to the foundation elevation. Grade and compact the bed to receive the footing.
208.09 Backfill. Place structural backfill in horizontal layers that do not exceed 6 inches (150 millimeters)
in compacted thickness. Compact each layer according to Subsection 208.10.
Place structural backfill layers evenly on all sides of the structure as appropriate. Extend each layer to the
limits of the excavation or to natural ground.
Do not place structural backfill against concrete until 80 percent of the design strength is achieved.
Backfill in or next to a running waterway according to Subsection 208.04.
208.10 Compacting. Determine optimum moisture content and maximum dry density according to
AASHTO T 99, Method C. Adjust the moisture content of the backfill material to a moisture content
suitable for compaction.
Compact material placed in all layers 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.
Do not apply density requirements as measured by AASHTO T 310 to material incapable of being tested
or compacted to maximum values determined by AASHTO T 99. For these material, fill the voids around
the rocky material in each layer with earth or other fine material. Compact each layer until there is no
visible evidence of further consolidation.
208.11 Acceptance. See Table 208-1 for sampling, testing, and acceptance requirements.
Material for structural backfill and foundation fill will be evaluated under Subsections 106.02 and 106.04.
130
Section 208
Material for grout will be evaluated under Subsections 106.02 and 106.03. Grout will be evaluated under
Subsections 106.02 and 106.04.
Structure excavation and backfill work will be evaluated under Subsections 106.02 and 106.04.
Clearing and removal of obstructions will be evaluated under Sections 201 and 203.
Seal concrete will be evaluated under Section 552.
Shoring, bracing, and cofferdams will be evaluated under Section 562.
Measurement
208.12 Measure the Section 208 pay items listed in the bid schedule according to Subsection 109.02 and
the following as applicable:
When measuring structural excavation by the cubic yard (cubic meter) in its original position; do not
include the following volumes in structure excavation:
(a) Material excavated outside the vertical planes located 18 inches (450 millimeters) outside and
parallel to the limits of the footings or foundations;
(b) Material included within the staked limits of the excavation (such as contiguous channel changes
and ditches) for which measurement is covered under other Sections;
(c) Water or other liquid material;
(d) Material excavated before measurement of the original ground;
(e) Material re-handled, except when the contract specifically requires excavation after embankment
placement; or
(f) Excavation for cofferdam seals.
When measuring foundation fill and structural backfill by the cubic yard (cubic meter) in place; measure
the volume placed inside the vertical planes located 18 inches (450 millimeters) outside and parallel to the
limits of the footings or foundations.
Payment
208.13 The accepted quantities will be paid at the contract price per unit of measurement for the Section
208 pay items listed in the bid schedule. Payment will be full compensation for the work prescribed in this
Section. See Subsection 109.05.
Payment for structure excavation, shoring and bracing, and cofferdams will be full compensation for
excavation to a depth of 6 feet (1.8 meters) below the lowest elevation shown in the plans for each
foundation structure. When the excavation exceeds 6 feet (1.8 meters), either the Contractor or the CO
may request an equitable price adjustment for the depth in excess of 6 feet (1.8 meters).
131
Section 208
Table 208-1
Sampling, Testing, and Acceptance Requirements
Material or
Type of
Characteristic
Category
Test Methods
Sampling
Point of
Split
Reporting
Product
Acceptance
Specifications
Frequency
Sampling
Sample
Time
(Subsection)
(Subsection)
Source
Foundation
Measured and
Classification
AASHTO
1 per
Source of
Yes
Before
fill(1)
tested for
M 145
soil type
material
using
(704.01)
conformance
in work
(106.04 & 105)
Gradation
AASHTO
"
"
"
"
T 27 & T 11
Structural
"
Plasticity index
AASHTO
"
"
"
"
backfill(1)
R 58, T 89, & T 90
(704.04)
Gradation
AASHTO
"
"
"
"
T 27 & T 11
Production
Foundation
Measured and
Moisture-
AASHTO
1 per
Source of
Yes
Before
fill
tested for
density
T 99,
soil type
material
using
(704.01)
conformance
Method C(2)
in work
(106.04)
Density
AASHTO
1 per
In-place
No
Before
T 310
300 yd3
placing
or other approved
(250 m3)
next layer
procedures
Structural
"
Moisture-
AASHTO
1 per
Source of
Yes
Before
backfill
density
T 99,
soil type
material
using
(704.04)
Method C(2)
in work
Density
AASHTO
2 per
In-place
No
Before
T 310
lift
placing
or other
next layer
approved procedures
(1)Not required when using Government-provided source.
(2) Minimum of 5 points per proctor.
132
Section 209
Section 209. — STRUCTURE EXCAVATION AND BACKFILL
Description
209.01 This work consists of excavating material for the construction of structures, except those
specifically designated under Section 208. This work also includes preserving channels, shoring and
bracing, sealing foundations, dewatering, preparing foundations, bedding, and backfilling.
Material
209.02 Conform to the following Sections and Subsections:
Backfill material
704.03
Bedding material
704.02
Foundation fill
704.01
Lean concrete backfill
614
Structural concrete, Class S (Seal)
552
Unclassified borrow
704.06
Construction Requirements
209.03 General. Clear the area of vegetation and obstructions according to Sections 201 and 203.
Excavate trenches or foundation pits according to Subsection 208.03. Excavate to foundation grade
without disturbing the trench or foundation surface. Foundation grade is the elevation at the bottom of the
bedding for installing the structure.
209.04 Channel Preservation. Preserve channels according to Subsection 208.04, except excavate inside
separations such as dikes or sandbags.
209.05 Foundation Seal. When foundation seals are necessary, construct a foundation seal according to
Subsection 208.06.
209.06 Dewatering. When dewatering is necessary, dewater according to Subsection 208.07.
209.07 Foundation Preparation. Excavate unsuitable material when encountered at foundation grade as
directed by the CO.
Where a footing is required to be keyed into undisturbed material, prepare foundation and construct
footing according to Subsection 208.08(c).
Backfill and compact with foundation fill according to Subsection 208.08(d).
209.08 Bedding. Place bedding as follows:
(a) For box culverts and structures other than pipe culverts. Construct bedding when specified.
Place and grade bedding material in compacted layers not exceeding 6 inches (150 millimeters) in
depth. Compact each layer according to Subsection 209.10.
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Section 209
(b) For pipe culverts. Level the foundation. Place uncompacted bedding material over the foundation
in a layer of uniform thickness. Lay a 4-inch (100-millimeter) thickness of bedding for pipes with
diameters of 12 to 54 inches (300 to 1350 millimeters). Lay a 6-inch (150-millimeter) thickness of
bedding for pipe with diameters larger than 54 inches (1350 millimeters). Recess the bedding to
receive the joints for pipes with belled joints. Place the culvert on the uncompacted bedding layer and
backfill according to Subsection 209.09(b).
209.09 Backfill. Backfill as follows:
(a) General. Place backfill layers evenly on all sides of the structure. Extend each layer to the limits of
the excavation or natural ground.
Place backfill material in compacted layers not exceeding 6 inches (150 millimeters) in depth.
Do not place backfill material against concrete until 80 percent of the design strength is achieved.
Compact each layer according to Subsection 209.10.
(b) Pipe culverts. Backfill according to one of the following:
(1) Pipe culverts. Place and compact backfill material in evenly balanced layers on each side of
the pipe to a height of 12 inches (300 millimeters) above the top of the pipe culvert.
Complete backfilling to the top of the trench. Place and compact backfill material in the trench in
layers not exceeding 6 inches (150 millimeters) in depth according to Subsection 209.10.
(2) Pipe culverts with lean concrete backfill. Place and anchor pipe to prevent floating and
movement. Backfill using lean concrete according to Section 614.
(c) Structural plate structures. Place and compact backfill material to a height of 12 inches
(300 millimeters) above the top of the structural plate structure. When applicable, complete backfilling
and compacting according to Subsection 204.10.
(d) Repair existing pavement areas. See Subsection 418.04.
209.10 Compacting. Determine optimum moisture content and maximum dry density according to
AASHTO T 99, Method C. Adjust the moisture content of the backfill material to a moisture content
suitable for compaction.
Compact material placed in all layers 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.
Do not apply density requirements as measured by AASHTO T 310 to material incapable of being tested
or compacted to maximum values determined by AASHTO T 99. For these material, fill the voids
around the rock in each layer with earth or other fine material. Compact each layer until there is no
visible evidence of further consolidation.
209.11 Acceptance. See Table 209-1 for sampling, testing, and acceptance requirements.
Material for backfill, bedding, and foundation fill will be evaluated under Subsections 106.02 and 106.04,
except lean concrete for bedding or backfill will be evaluated according to Section 614.
134
Section 209
Structural excavation and backfill work will be evaluated under Subsections 106.02 and 106.04.
Shoring and bracing will be evaluated under Subsections 106.02 and 106.04.
Clearing and removal of obstructions will be evaluated under Sections 201 and 203.
Seal concrete will be evaluated under Section 552.
Measurement and Payment
209.12 Do not measure structure excavation and backfill for payment. See Subsection 109.05.
Measure foundation fill under Section 208.
Do not measure excavation and concrete for cofferdam seals for payment.
135
Section 209
Table 209-1
Sampling, Testing, and Acceptance Requirements
Material or
Type of
Characteristic
Category
Test Methods
Sampling
Point of
Split
Reporting
Product
Acceptance
Specifications
Frequency
Sampling
Sample
Time
(Subsection)
(Subsection)
Source
Backfill
Measured and
Classification
AASHTO
1 per
Source of
Yes
Before
material(1)
tested for
M 145
soil type
material
using
(704.03)
conformance
in work
(106.04 & 105)
Gradation
AASHTO
"
"
"
"
T 27 & T 11
Bedding
"
"
"
"
"
"
"
material(1)
(704.02)
Foundation
"
Classification
AASHTO
"
"
"
"
fill(1)
M 145
(704.01)
Gradation
AASHTO
"
"
"
"
T 27 & T 11
Unclassified
"
Classification
AASHTO
"
"
"
"
borrow(1)
M 145
(704.06)
136
Section 209
Table 209-1 (continued)
Sampling, Testing, and Acceptance Requirements
Material or
Type of
Characteristic
Category
Test Methods
Sampling
Point of
Split
Reporting
Product
Acceptance
Specifications
Frequency
Sampling
Sample
Time
(Subsection)
(Subsection)
Production
Backfill
Measured and
Moisture-
AASHTO
1 per
Source of
Yes
Before using
material
tested for
density
T 99,
soil type
material
in work
(704.03)
conformance
Method C(2)
(106.04)
Density
AASHTO
2 per
In-place
No
Before placing
T 310 or other
lift
next layer
approved procedures
Bedding
"
Moisture-
AASHTO
1 per
Source of
Yes
Before using
material
density
T 99,
soil type
material
in work
(704.02)
Method C(2)
Density
AASHTO
2 per
In-place
No
Before placing
T 310 or other
lift
next layer
approved procedures
Foundation
"
Moisture-
AASHTO T 99,
1 per
Source of
Yes
Before using
fill
density
Method C(2)
soil type
material
in work
(704.01)
Density
AASHTO
2 per
In-place
No
Before placing
T 310 or other
lift
next layer
approved procedures
Unclassified
"
Moisture-
AASHTO
1 per
Source of
Yes
Before using
borrow
density
T 99,
soil type
material
in work
(704.06)
Method C(2)
Density
AASHTO
2 per
In-place
No
Before placing
T 310 or other
lift
next layer
approved procedures
(1) Not required when using Government-provided source.
(2) Minimum of 5 points per proctor.
137
Section 210. — RESERVED
138
Section 211
Section 211. — ROADWAY OBLITERATION
Description
211.01 This work consists of obliterating or closing roadways and other areas outside the roadway prism.
Roadway obliteration methods are designated as follows:
(a) Method 1. Obliterate the roadway by restoring to approximate original ground contours. Keep
excavated material within the original construction limits. Finish slopes to provide gradual transitions
in slope adjustments without noticeable breaks.
(b) Method 2. Close roads by filling ditches and outsloping the roadbed to drain. Remove and slope
embankment material at localized drainages to restore the natural drainage patterns. Eliminate ruts and
low spots that could hold water.
Construction Requirements
211.02 Conform to the following when obliterating or closing roadways:
(a) Rigid material.
(1) Nonasphalt material. Break concrete pavements, curbs, gutters, sidewalks, and other
nonasphalt rigid material into pieces with maximum dimension of 12 inches (300 millimeters)
when burying according to Subsection 203.05(c). As an alternative to breaking and burying,
remove the rigid material from the project and dispose of it according to Subsection 203.05(a).
(2) Asphalt material. Dispose of asphalt material in a manner consistent with state and local
regulations. Asphalt material may be considered hazardous waste. Submit copies of the disposal
permits. Where no regulations exist, dispose of the material as described in
Subsection 211.02(a)(1).
(b) Nonrigid material.
(1) Nonasphalt material. Scarify or rip the gravel, crushed stone, or other nonrigid surface,
base, and subbase material. Mix the scarified or ripped material with the underlying soil. Bury
the mixture under at least 12 inches (300 millimeters) of soil.
(2) Asphalt contaminated material. Dispose of asphalt contaminated material according to
Subsection 211.02(a)(2).
211.03 Waterbars and Barriers. Construct barriers to prevent vehicle access and waterbars as shown in
the plans.
211.04 Acceptance. Roadway obliteration will be evaluated under Subsection 106.02.
139
Section 211
Measurement
211.05 Measure the Section 211 pay items listed in the bid schedule according to Subsection 109.02.
Payment
211.06 The accepted quantities will be paid at the contract price per unit of measurement for the Section
211 pay items listed in the bid schedule. Payment will be full compensation for the work prescribed in this
Section. See Subsection 109.05.
140
Section 212
Section 212. — LINEAR GRADING
Description
212.01 This work consists of constructing roadbeds within the specified alignment and grade tolerances.
Construction Requirements
212.02 Roadway Preparation. Clear the area of vegetation and obstructions according to Sections 201
and 203.
212.03 Roadway Excavation and Embankment. Construct the roadbeds according to the applicable
requirements of Section 204, except as modified herein.
Adjust the moisture content of embankment material to a moisture content suitable for compaction. Place
embankment material in 12-inch (300-millimeter) layers and compact each layer according to Subsection
204.11(a). Where compacting with rollers is not practical, use approved mechanical or vibratory
compaction equipment.
Construct approach connections to existing roads, parking areas, and trails. Construct new approaches.
212.04 Grading Tolerance. Do not encroach on stream channels, impact wetlands, or extend beyond
right-of-way or easement limits. Do not make alignment or profile grade adjustments that adversely affect
drainage. Construct the roadbed within the following grading tolerances:
(a) Alignment (centerline). Alignment may be shifted a maximum of 10 feet (3 meters) left or right of
the planned centerline. Curve radii may be reduced by up to 50 percent. Do not construct curves with
radii less than 100 feet (30 meters). Compound curves are permitted.
(b) Profile grade. Profile grade may be shifted a maximum of 5 feet (1.5 meters) up or down from the
plan elevation provided the new grade tangent does not vary more than 2 percent from the plan grade
tangent. Connect revised forward and back grade tangents with a uniform vertical curve consistent
with the design.
212.05 Acceptance. Linear grading will be evaluated under Subsections 106.02 and 106.04.
Clearing and removal of obstructions will be evaluated under Sections 201 and 203.
Measurement
212.06 Measure the Section 212 pay items listed in the bid schedule according to Subsection 109.02 and
the following as applicable.
Do not measure changes in the clearing and grubbing quantity caused by alignment adjustments under
Subsection 212.04.
141
Section 212
Payment
212.07 The accepted quantities will be paid at the contract price per unit of measurement for the Section
212 pay items listed in the bid schedule. Payment will be full compensation for the work prescribed in this
Section. See Subsection 109.05.
142
Section 213
Section 213. — SUBGRADE STABILIZATION
Description
213.01 This work consists of processing and incorporating lime, lime/fly ash, or hydraulic cement into the
upper layer of subgrade.
Material
213.02 Conform to the following Subsections:
Chemical admixtures
711.03
Fly ash
725.04(a)
Hydraulic cement
701.01
Lime for soil stabilization
725.03(b)
Water
725.01(c)
Construction Requirements
213.03 Proportioning. Submit a subgrade stabilization mix design at least 30 days before production.
Include compressive strength values for at least three application rates with at least one application rate
above and one below the strength shown in Table 213-1.
Table 213-1
Subgrade Stabilization Compressive Strength Requirements
Stabilization
Test
Average Unconfined Compressive
Mixture
Procedure
Strength (minimum of 3 specimens)
Lime/Soil
ASTM D5102,
100 pounds per square inch
Procedure B
(0.70 megapascals)(1)
Lime/Fly ash/Soil
ASTM D5102,
150 pounds per square inch
Procedure B
(1.0 megapascals)(1)
Cement/Soil,
ASTM D1633,
200 pounds per square inch
Cement/Fly ash/Soil,
Method A
(1.4 megapascals)(2)
or Fly ash/Soil
(1) At 7-day cure at 105 °F (40 °C).
(2) At 7-day cure.
Include the following with the mix design as applicable:
(a) Source of each component material;
(b) Results of the applicable tests including optimum moisture content (after treatment), hydration
moisture rate, maximum dry density (after treatment), Atterberg limits (before and after treatment),
and recommended application rates of stabilizing material; and
143
Section 213
(c) When requested by the CO:
(1) 200-pound (90-kilogram) sample of the subgrade soil;
(2) 25-pound (12-kilogram) sample of the fly ash;
(3) 25-pound (10-kilogram) sample of the lime;
(4) 25-pound (10-kilogram) sample of the cement; and
(5) 2-pound (1-kilogram) sample of each chemical admixtures.
Begin production after the mix design is approved. Furnish a new mix design if there is a material source
change.
213.04 Production Start-Up Procedures. Conduct a pre-stabilization preparatory phase meeting at least
7 days before the start of stabilizing operations according to Subsection 153.04(a).
Provide at least 7 days notice before beginning production.
213.05 General. Store lime, fly ash, hydraulic cement, and chemical admixtures in closed, weatherproof
containers.
Prepare the subgrade according to Subsection 303.05. Scarify or pulverize the subgrade to the required
depth. Use a rotary mixer with direct water injection capabilities to adequately blend the material and to
produce a homogeneous mixture within 2 percent of the optimum moisture content.
At the end of each production day, shape the subgrade surface to provide positive drainage. Provide a
construction joint according to Subsection 305.11 for tying into existing stabilized subgrade.
213.06 Application. Do not apply lime, fly ash, or hydraulic cement when weather conditions cause
excessive material loss or when the air temperature may fall below 32 °F (0 °C) within 48 hours. Apply
material when the subgrade material temperature is at least 40 °F (5 °C).
Adjust the subgrade material moisture content to 2 to 3 percent above optimum.
Apply fly ash by the dry method. Apply lime and cement by either the dry or slurry method.
(a) Dry method. Uniformly apply the stabilizers using a metered spreader approved by the CO. A
motor grader is not an approved spreader. Apply water using approved methods to obtain the proper
moisture content for mixing and compaction. If quicklime and fly ash are pre-blended, limit the
maximum particle size of the quicklime to ⅛ inch (3 millimeters) to avoid segregation.
(b) Slurry method. Mix material with water. Report the percent solids in the slurry to the CO for each
production day. Apply the slurry using either trucks with approved distributors or rotary mixers. Equip
the distributor truck or rotary mixer tank with an agitator to keep the stabilizers suspended in water.
Make successive passes over the material to obtain the proper moisture and additive content.
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