205DRILLING AND BLASTING

205

2-31SECTION 205 – DRILLING AND BLASTING

205.01DESCRIPTION . This work shall consist of drilling and blasting of rock, in accordance with these

specifications, the Plans, and as directed by the Engineer.

205.02DRILLING AND BLASTING OF SOLID ROCK SUBGRADE . Solid rock subgr ade areas shall

be shattered in place to the dimensions shown on the Plans or directed by the Engineer. The area of blasted rock subgrade shall extend sufficiently beyond the beginning and end of cut areas to ensure the shattering of all rock to a depth of 4 feet below the bottom of subbase material elevation. After detonation, any rock protruding above the bottom of subbase shall be removed. When directed by the Engineer, the Contractor shall excavate a trench with conventional earth moving equipment across the blasted rock to determine if the rock is sufficiently shattered to a depth of 4 feet below the bottom of subbase. Afterwards, the trench shall be backfilled with the rock removed.

205.03DRILLING AND BLASTING USING PERIMETER CONTROL . Perimeter contr ol blasting

refers to the use of explosives and blasting accessories in carefully spaced and aligned drill holes to produce a final excavation surface or shear plane in the rock along the specified excavation backslope. These blasting techniques are used t o better distribute the explosive charge to minimize damage, such as fracturing and overbreak, backbreak, or endbreak, beyond the final excavation face. This is accomplished by using small diameter, decoupled charges in closely spaced blastholes placed on the perimeter of an excavation. Perimeter control blasting methods include line drilling, presplitting, and precision presplitting.

explosives for breaking rock. The blasting contractor shall be responsible for loading and firing each blast, as well as the design and management of blasting operations.

and security of explosives, and is responsible for coordinating, planning, and supervising explosives use. The blaster -in-charge shall be responsible for inspecting blast areas after each blast event. The blaster -in-charge will be required to be on -site during blasting.

205 2-32 (3) Blasting Consultant . The blasting consultant shall have specialized experience and academic knowledge of commercial explosives, perimeter control blasting applications, vibration, and air -overpressure control. The blasting co nsultant shall use this knowledge to evaluate, plan, and oversee the safe use of explosives in commercial applications in accordance with blasting industry and regulatory standards. The blasting consultant shall review and sign all blasting plans and requi red submittals provided by the blasting contractor. The blasting consultant shall not be an employee of the Contractor or any affiliated companies or suppliers of products to the project and shall not have any conflict - of-interest affiliations with the Age ncy, or other entities involved with the work. The Blasting Consultant shall be required per the Contract documents.

airblast monitoring for blasting events. The vibration specialist shall conduct the operation and deployment of seismographs, geophones, and airblast monitoring equipment for all blasting operations. The vibration specialist shall also be available to discuss vibration results at the request of the A gency. The vibration specialist shall not be an employee of the Contractor or any affiliated companies or suppliers of products to the project and must not have any conflict -of-interest affiliations with the Agency, or other entities involved with the work .

the work. Review and acceptance of submittals does not relieve the Contractor of responsibility for the blast results or liability. The Contractor is entirely responsible for the work associated with these submittals.

to the beginning of the work. Once a complete submittal has been received, the Agency shall be allowed 21 calendar days for the initial review period and shall be allowed 14 calendar days for review of each sub sequent resubmittal. The pre -construction submittals shall be submitted at least 10 working days prior to the pre -blast meeting, outlined in Subsection 205.03(d) . Drilling and blasting operations shall not begin until all of the submittals have been approved in writing by the Engineer.

205 2-33 a. Qualifications .

blasting contractor has successfully completed at least five blasting projects within the last 3 years with subsurface conditions and blasting of a similar scope and complexity to that anticipated. Docu mentation shall include the names of the general contractor and the owner, descriptions of each past project, and current contact information of a representative of the construction manager or project owner. Contact information shall include at least one v alid phone number.

in-charge and any alternates assigned to the project. The Contractor shall provide documentation of valid licenses for each blaster -in-charge, including sta te of Vermont Department of Public Safety Explosive License and U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives License. Documentation shall be provided showing that each blaster -in-charge has a minimum of 10 years of experience in blasting with p ast projects of scope and complexity similar to that anticipated. University education in the field of explosive engineering may be submitted by the Contractor to supplement experience per approval of the Engineer. Documentation shall include resumes, refe rences, certifications, project lists, experience descriptions and details. References shall include valid phone numbers for the representatives of the construction manager or project owner from at least 3 past projects involving similar perimeter control blasting. The Contractor shall also provide documentation that each blaster -in-charge attended at least 5 blasting seminars, short courses, or blasting conferences in the last 10 years, and shall include a signed statement from the proposed blaster -in-charge certifying that during the past 5 years they:

205 2-34 i. Have not been involved in incidents where flyrock traveled within the active travel way, out of the construction right -of-way, onto private property, caused damage of property, or resulted in injury. ii. Have not had a blasting license restricted or revoked in any state. iii. Have not been fined or sanctioned personally in any way by a regulating authority.

blasting consultan t has a minimum of 10 years of experience in using perimeter control blasting on projects of scope and complexity similar to that anticipated. The blasting consultant shall have directly participated in at least three projects of similar scope and complexi ty. Documentation shall include the names of the general contractor and the owner, descriptions of each past project, and current contact information of a representative of the construction manager or project owner. Contact information shall include at lea st one valid phone number.

vibration specialist has directly participated in at least five rock slope and rock removal projects. The documentation shall contain a description of t he projects, details of the vibration control plans, and modifications made during the project. The documentation shall include the names of the general contractor and the owner, and current contact information of a representative of the construction manager or project owner. Contact information shall include at least one valid phone number.

beginning drilling, when revised drilling or blasting methods are proposed, or a s directed by the Agency. The preliminary blast plan shall clarify the means and methods anticipated to be used during construction to meet blasting tolerances stated in the Contract. The preliminary blast plan shall include, but not be limited to:

205 2-35 1. A description of the sequence and procedures to be employed to execute the anticipated blasting operations including the drilling, blasting, fragmentation size, number of blasts, benching details if applicable, and proposed blasting schedule.

and perimeter control holes as applicable, the type of drills, size and type of drill bits, drill hole inclinations, anticipated subdrill depths, burden between rows, hole spacing within rows, and hole diameter.

sectional views, free faces, burden, bench or lift heights, station limits, blast limits, hole types, burden, hole spacing, depths, diameters, subdrill depths, and inclination.

to be used, detonators, boosters, blasting agents, type and amount of stemming, method of primary initiation, sequence of delays, any blank or unloaded holes, and detonation methods and timing and loading di agrams.

material and equipment proposed, including the type of explosives, blasting agents, cartridge sizes and weights, detonators, blast initiation devices, and other equipment required to perform the blast.

type, size, weight, and number.

equipment, materials and waste, and other significant aspects of the work related to drilling and blasting.

for the portion of the work involving drilling and blasting.

205 2-36 11. Examples of all forms used in the Contractor’s submissions. Individual forms may require revision for the Agency’s approval.

preliminary blast plan.

include a pre -blast condition survey of all buildings, structures, or utilities within a radius of the blasting a rea limits as specified on the Plans. The Contractor shall also notify the residents and owners of these buildings, structures, or utilities of the scheduled blasting activities. At a minimum, notification shall include a certified letter. The pre -blast condition survey shall be conducted by the vibration specialist. Additional buildings, structures, or utilities outside of the radius of the blasting area limits may require a survey and notification , as directed by the Engineer. The vibration and noise co ntrol plan shall include, but is not limited to:

survey, including the address or location, owner, and date and time of the

survey.

its existing condition included in the pre-blast condition survey. The

Contractor shall also furnish the Engineer with a list of the residents and

owners who were contacted and proof of notification.

otherwise deteriorated structural conditions documented in the pre-blast

condition survey. Photos and digital recordings shall contain an accurate

date stamp.

utility within the radius of the blasting area limits.

to be used to estimate ground vibrations and airblasts.

scaled map showing locations and the distance from the center of the blast

area to the instrument location.

205

at the project location.

recorders, seismographs, sensors, and microphones. The records shall show

that the monitoring equipment has been calibrated within 12 months.

forms may require revision for the Agency’s approval.

Any equipment used to monitor the condition of any existing conditions revealed

during the pre-blast surveys shall be installed and maintained per the direction and

recommendation of the vibration specialist. The vibration specialist shall be

responsible for recommending the appropriate equipment to be used.

work procedures and safety precautions for the storage, transportation, and

handling of explosives including:

transportation, storage, handling, and use of explosives; copies of all

required blasting permits regarding explosive use and storage; and copies

of necessary blasting licenses or authorizations obtained from the state and

pertinent localities.

day boxes or delivery vehicles while on site.

guarded to prevent unauthorized use of explosives.

and safety precautions for the detonation of explosives including:

procedures; signage; and equipment details.

and other natural resources.

205

employed to ensure personnel, staff, visitors, and all other persons are at

safe locations during blasting. This information shall include details

regarding visible warning signs or flags, audible warning signals, method

of determining blast area zones, access blocking methods, guard placement

and guard release procedures, primary initiation method, and the system by

which the blaster-in-charge will communicate clearing and guarding

procedures.

the approach of lightning storms and, in the event of such, evacuation and

site safety security plans. This includes specifications of the lightning

detection equipment.

limitations for work involving any open flames or sparks, description and

location of all firefighting equipment, and firefighting and evacuation plans.

Engineer no later than 8:00 a.m. on the weekday prior to the proposed upcoming blast. The

Agency shall be allowed 8 hours to review the submittal and each resubmittal. Reviews

will only be conducted on weekdays. Explosive materials shall not be delivered to the site

until the submittals have been approved in writing by the Engineer.

Engineer. The review of a blasting plan by the Agency shall not relieve the

Contractor of responsibility to produce adequate rock breakage, to limit breakage

to within the design excavation final lines and grades, that project vibration limits

are not exceeded, and to ensure that flyrock does not result from the blasting

operation. The pre-blast plan shall include, but not be limited to:

depth of blastholes relative to the specified stations, slopes, lines, and

grades.

205

stemming used in all charged holes, rock volume calculations, and powder

factor calculations.

potential.

not intended to be removed or disturbed by the blast.

and instruments that will measure ground and air blast vibrations. Locations

shall be in degrees latitude and longitude, recorded with a hand-held GPS

unit.

different angles or locations. Videos must be obtained from a location that

is close enough to adequately show the blast occurring.

drilling logs.

that includes a record of all holes drilled. An example drill log form is available

from the Agency Geologist per request. At a minimum, drill logs shall include:

drilling equipment used.

operation.

205

holes, buffer holes, presplit or precision presplit holes, and line drilling

holes shall be identified as appropriate.

borehole inclination, and any deviation from planned angle at each borehole

drilled.

encountered during drilling of each hole, including but not limited to:

ii. Zones where loss or gain of fluid or air is encountered.

iii. Changes in lithology.

iv. Changes in the rate of drilling not due to equipment.

vi. Odors emanating from the drill hole.

vii. Soil types encountered.

viii. Water bearing zones.

in the drill log.

contained in the drill logs.

205

report. An example borehole tracking report form is available from the Agency

Geologist upon request. For each perimeter control blasthole, this shall include, but

is not limited to:

borehole path).

5.. Average inclination.

6.. Deviation from the inclination shown on the Plans.

of the borehole).

specification tolerances for inclination, the number of holes not in

conformance, and the amount to which they are out of tolerance.

tolerance.

not less than 48 hours after each blast and before any further blasting operations can

continue. Post-blast reports must be completed and accepted by the Agency before the next

pre-blast plan is submitted. The Agency shall be allowed 8 hours to review the submittal

and each resubmittal. Reviews will only be conducted on weekdays.

205

a full detailed account of the blast. An example post-blast report is available from

the Agency Geologist upon request. This shall include, but is not limited to:

ii. Final burden, spacing and number of holes blasted.

iii. Calculated volume of blast.

iv. Explosive details, including, load parameters, including type,

quantity, size, weight of explosives, per type, overall total, and

stemming type and depths.

perimeter control blastholes.

vi. Total number and type of delays used, number of holes for each

delay period, and sequence of time delay.

vii. Typical blasthole profiles showing the details of the loading,

including subdrilling.

viii. Number of blasting mats used, type, placement, or other methods to

control flyrock.

bottom areas.

ii. Evidence of backbreak, overbreak, endbreak or blast damage along

the new slope face including within any half barrel casts. Include

station limits and estimated dimensions of damage.

205

iii. Amount and measured distance of flyrock ejected.

iv. Any intersections or areas of over loading or under loading as shown

in the constructed rock slope face.

blasting consultant of the blast performance.

vi. Corrective actions to the blast design and methods should the results

of the blasting violate any section of the specification, or the

tolerances and intent shown on the Plans.

camera (e.g. Blast 01 – Position A).

ii. Video recordings shall begin at least 10 seconds before the blast and

continue recording until there is no evidence of visible dust.

vibration and airblast data. This shall include, but is not limited to:

elevation) and the blast area center location (station and offset, latitude and

longitude, and elevation).

station and the coupling method.

205

ii. Peak particle displacement.

iii. Peak acceleration.

iv. Peak vector sum.

vi. Maximum charge weight per delay.

vii. Airblast overpressure.

viii. Confirmation that the vibration data shows conformation with the

vibration limits.

ix. Calibration verification.

(square root) to peak particle velocity, and scaled distance (cube root) to

airblast pressure level.

and airblast readings.

construction right-of-way, onto private property, causes damage of property, or

results in injury, the blasting contractor shall file a flyrock report. This report shall

be reviewed by the blasting consultant and submitted to the Engineer for approval

before blasting operations resume. This shall include, but is not limited to:

205

flyrock.

report. This report shall be reviewed by the blasting consultant and submitted to the

Engineer for approval before blasting operations resume. This includes, but is not

limited to:

overburden, and boulders prior to beginning blasting work. Use of explosive charges is not

permitted to blast boulders or remove less than 3 feet of rock above grade. Boulders shall be broken

in a manner that shall not dislodge them and cause them to move downslope. The methods allowed

for boulder breaking include hydraulic splitter and hydraulic hammer. Alternative methods of

boulder removal may be proposed by the Contractor and submitted to the Engineer for approval.

and shall be attended by the Agency, the Contractor, the blasting contractor, blaster-in-charge,

blasting consultant, and vibration specialist. The pre-blast meeting shall be conducted to clarify

the construction requirements for the work, to coordinate construction activities, and to identify

contractual relationships and responsibilities. The pre-construction submittals, outlined in

Subsection 205.03(b)(1), shall be submitted at least 10 working days prior to the pre-blast meeting.

the request of the Engineer, the Contractor shall make their blasting consultant, blasting contractor,

and vibration specialist prepare for and participate in a public meeting conducted by the Engineer.

The participants shall be prepared to answer any questions regarding the blasting operations,

ground vibrations, airblast overpressure, and flyrock expected to impact the public.

205

the project to review the progress of the blasting operations, discuss modifications to the methods

and procedures of the written blast plan, or discuss issues with upcoming blasts. Blasting progress

meetings shall be attended by the Agency, the Contractor, the blasting contractor, and other

interested parties.

controlled, stored, and monitored in accordance with Subsection 107.10.

shall drill, blast, and muck test sections, up to 100 feet in length, to determine if their proposed

blast design, including hole spacing, timing, and charges, will meet the objectives of the Contract.

If more than one blast design is tested in one test blast, each design section shall be at least 20 feet

in length along the final face surface.

All requirements for blasting operations covered elsewhere in this specification shall apply to the

blasting carried out in conjunction with the test blast.

The blasting contractor will not be allowed to drill ahead of the test blast until the results have

been evaluated and approved by the Engineer. If the results of the test blasts are unsatisfactory,

then, notwithstanding the Engineer’s prior review of such methods, the blasting contractor shall

adopt revised methods as necessary to achieve the required results.

Unsatisfactory test blast results include an excessive amount of overbreak, backbreak, or endbreak

beyond the indicated lines and grade, flyrock, ground vibration, airblast or violation of other

requirements within these specifications, or unsatisfactory condition of the constructed rock slope

face, such as not producing a uniform rock slope face. No additional compensation will be allowed

for costs incurred by the blasting contractor in adopting revised blasting methods necessary to

produce an acceptable test blast.

If the Engineer suspends blasting operations after full scale blasting has begun, test blasts will be

required before full scale blasting can resume.

205

technique consisting of a series of closely spaced holes that are not loaded with

explosives and are drilled along the excavation line. The line drill hole spacing shall

be no greater than twice the line drill hole diameter as stated in the Plans.

row of closely spaced, lightly loaded blastholes placed on the perimeter of the

excavation and fired before the production holes.

The presplit blastholes shall be a minimum of 2 inches and maximum of 3 inches

in diameter. The presplit holes shall be drilled with a minimum spacing of 10 times

the presplit hole diameter and a maximum spacing of 12 times the presplit hole

diameter. Presplit hole loads are limited to 0.35 pounds of explosive per foot of

blasthole. The maximum diameter of explosives used in presplit holes shall not be

greater than half the diameter of the presplit hole.

Presplit blastholes shall be fired before production holes. If presplitting and

production holes are fired within the same blast, all presplit blastholes shall be fired

at least 25 milliseconds before the production blastholes are detonated. Line drilling

along final walls may be required at corners where presplit lines meet. Subdrilling

2 feet below ditch bottom will be allowed to facilitate removal of the toe berm.

spaced blastholes than presplitting with lighter explosives loads. This method of

perimeter control matches the strength of the explosives to the strength

requirements of the rock to cause the web of rock between the precision presplit

holes to fail in tension with the minimum energy needed and to create the split

without damaging the constructed rock cut face.

The precision presplit blastholes shall be a minimum of 2 inches and maximum of

3 inches in diameter. The precision presplit holes shall be drilled with a minimum

spacing of 4 times the precision presplit hole diameter and a maximum spacing of

8 times the precision presplit hole diameter. Subdrilling 2 feet below ditch bottom

will be allowed to facilitate removal of the toe berm.

205

and shall be designed to control flyrock, minimize ground vibration and airblast, and result

in loosened and fragmented rock suitable for excavation using conventional earth moving

equipment.

Production blastholes shall be in a consistent pattern that does not affect the perimeter

control blastholes. To control blasting effects, the blasting contractor shall maintain a

burden distance that is not more than one half the bench height and between 25 times and

35 times the diameter of the explosive charge in the blasthole. If the first row of production

holes adjacent to the presplit face are intended to be buffer holes, they shall be drilled no

less than 4 feet from the presplit line and shall maintain a stand-off distance between the

production explosive charges and the presplit line of no less than three 3 feet. Sub drilling

2 feet below ditch bottom will be allowed to facilitate removal of the toe berm.

control blast line. Buffer holes may be battered at the same angle as the presplit face or

may be vertical.

overburden and debris from falling into the holes. All blastholes shall be marked

with the hole number and depth. Blastholes shall be free of obstructions for their

entire depth.

equipment and techniques to ensure that no hole deviates from the tolerance set for

both depth and alignment.

All drilling equipment used to drill blastholes shall be equipped with an electro-

mechanical or electronic device that accurately determines the angle, within 1

degree, at which the drill steel enters the rock. Drilling will not be permitted if these

devices are either missing or inoperative.

205

unit affixed to a laser profiler to determine blasthole orientation on all perimeter

control blastholes. The blasting contractor shall submit the borehole tracking data

as outlined in Subsection 205.03(b)(2)c. This requirement may be waived

temporarily when, in the opinion of the Engineer, the borehole alignment is

satisfactory. Required borehole tracking may be reinstated at the discretion of the

Engineer.

Any blastholes deviating from alignment on the plane of the planned slope, either

parallel or normal to the slope, by more than the tolerances shown on the Plans,

shall be refilled with crushed stone stemming or cementitious grout, re-drilled at

the proper location and at the proper alignment, and borehole tracked, at no

additional cost to the Agency.

collapses, or other debris, including removal of water if using non-water-resistant

explosives. All blastholes shall be checked and measured before any explosives are loaded

into any of the holes to eliminate any safety hazard resulting from drilling near loaded

holes.

Stemming material used in production holes shall consist of dry, unfrozen, angular crushed

stone having an optimum average diameter of 0.05 times the diameter of the blasthole.

Drill cuttings shall not be used as stemming, with the exception of precision presplit

blastholes.

If fractional portions of standard explosive cartridges are used, they shall be firmly affixed

to the detonating cord in such a manner that the cartridges will not slip down the detonating

cord nor bridge across the hole. Spacing of fractional cartridges along the length of the

detonating cord shall not exceed 30 inches center to center and shall be adjusted to produce

the desired results.

Continuous column cartridge types of explosives used with detonating cord shall be

assembled and affixed to the detonating cord in accordance with the explosive

manufacturer’s instructions, a copy of which shall be furnished to the Engineer.

The bottom charge of a presplit or precision presplit hole may be larger than the line

charges but shall not be large enough to cause overbreak. The top charge of the presplit or

precision presplit hole shall be placed far enough below the collar, and reduced sufficiently,

to avoid overbreaking and heaving. The upper portion of all presplit and precision presplit

holes, from the topmost charge to the hole collar, shall be stemmed.

205

following each blast to allow inspection of the rock cut, approval of the blast face, and

allow for adjustments to the blast design for subsequent blasts. All rock on the constructed

cut face that is loose, hanging, or which creates a potentially dangerous situation due to

risk of rockfall occurring shall be removed to the satisfaction of the Engineer during or

upon completion of the mucking. Drilling and loading for the next blast will not be allowed

until the required mucking of the previous blasts has been completed and the face is

approved. If subsequent blasting causes damage to an already approved area, then the

damaged areas will be readdressed to the satisfaction of the Engineer.

as directed by the Engineer, as needed.

If subsequent blasting causes damage to an already approved stabilized area, then the area may be

required to be restabilized at the discretion of the Engineer.

as outlined in Subsection 205.03(b)(1)c. The vibration specialist shall establish the safe ground

vibration and airblast limit for each building, structure, and utility within the radius of the blasting

area limits, as specified on the Plans.

and airblast at each building, structure, and utility within the radius of the blasting area

limits, as specified on the Plans.

vibration specialist shall be responsible for guaranteeing the appropriate

number of seismographs are used in blasting operations. Locations shall be

included in the vibration and noise control plan, as outlined in Subsection

(b)(1)c., and be approved by the Engineer. The vibration data

collected by these seismographs will be used to ensure excessive vibration

is not being transmitted into the rock mass beyond the presplit face.

concurrence of the Agency and the vibration specialist.

205

contractor shall monitor each blast with approved seismographs located

between the blast area and the closest structures subject to blast damage.

natural soils to ensure full coupling.

standards established by the Vibration Section of The International Society

of Explosives Engineers.

in the three mutually perpendicular components of vibration in the range

generally found with perimeter control blasting, the vector sum of these

peak particle velocities, and the frequency history of the vibrations.

the time of use and operated by properly trained personnel.

shall not be allowed to exceed the safe limits of the nearest structure subject

to vibration damage or at areas designated in the Plans, as determined by

the vibration specialist, and as approved by the Engineer.

each blast.

appropriate number of airblast monitoring instruments are used in blasting

operations. Locations shall be included in the vibration and noise control

plan, as outlined in Subsection 205.03(b)(1)c., and be approved by the

Engineer.

205

area and the nearest structures subject to blast damage, annoyance, or at

areas designated on the Plans.

manufactured for that purpose and shall be approved by the Engineer.

operated by properly trained personnel.

or other designated locations when measured using a 0.1 Hz high-pass linear

peak method.

used to prevent venting of blasts and to minimize airblast and noise levels

produced by the blasting operations.

damage or complaints.

and airblast data and report as outlined in Subsection 205.03(b)(3)b.

The vibration specialist shall keep an up-to-date database of the vibration data that shall

include ground vibration and airblast data for each blast event. The database shall include

regression analysis of both ground vibration and airblast data. The information from this

database shall be made available to the Agency upon request.

following shall apply:

205

blasting and immediately repair or replace any utilities damaged by the blasting

operations. If the blasting contractor wishes to temporarily relocate any utility lines

that lie near a blast zone, they shall have written approval from the governing

utilities and pay all relocation costs.

with blasting mats or other suitable materials to prevent formation of any flyrock.

The method of covering shall be approved by the Engineer.

of-way, onto private property, causes damage to state or private property, or results in

injury, the blasting contractor shall file a flyrock report as outlined in Subsection

(b)(3)c

Subsection 107.10.

if it is apparent that through the methods being employed the blasted slopes are unstable or that

the safety and convenience of the traveling public is being jeopardized.

107.10

following a blast to guard against rockfall before commencing work in the cut. The

delay between blasting and allowing anyone but the blaster-in-charge to enter the

area is needed to make sure that no misfires have occurred.

It is the blaster-in-charge’s responsibility to go into the blast area and check all

holes to make sure that they have detonated. If any holes have not fired, these

misfires will be handled by the blaster-in-charge before others enter the work area.

205

occur, only critical personnel involved in the blasting operation or excavation of

the unexploded material will be allowed within the established blasting area.

Access to the site shall be restricted until the blaster-in-charge indicates that the site

is safe.

If the misfire poses problems that cannot be safely corrected by the blaster-in-

charge, a consultant, or an explosives company representative skilled in correcting

misfires shall be consulted to resolve the problem. Compliance with this or any

other provision in the Contract shall not relieve the Contractor of responsibility for

any damage or injuries caused by, related to, or arising out of blasting or associated

blasting activities. Costs associated with resolving misfire problems will be the sole

responsibility of the Contractor.

report as outlined in Subsection 205.03(b)(3)d.

205.04METHOD OF MEASUREMENT. The quantity of Drilling and Blasting of Solid Rock Subgrade

to be measured for payment will be the number of square yards of subgrade plan area drilled and detonated

in accordance with this section, measured at the bottom of subbase. The number of cubic yards of

excavation required by the Engineer to inspect the depth of shattered and rearranged rock, computed at a

maximum width of 30 inches, will be measured for payment as Trench Excavation of Earth. Any area

designated as Trench Excavation of Rock will not be included in the measurement and payment for

Drilling and Blasting of Solid Rock Subgrade.

The quantity of Drilling and Blasting Using Perimeter Control to be measured for payment will be the

number of cubic yards of rock blasted and mucked to the constructed rock slope face limits shown on the

Plans.

205.05BASIS OF PAYMENT. The accepted quantity of Drilling and Blasting of Solid Rock Subgrade

will be paid for at the Contract unit price per square yard. Payment will be full compensation for

performing the work specified including any necessary stripping of rock below the bottom of subbase and

refilling with approved material to the bottom of subbase, the removal of blasted subgrade rock that may

swell above subgrade, and its disposition on the project as shown in the Plans or as directed by the

Engineer. Excavation and backfill required to inspect the depth of broken rock below subgrade will be

paid for at the Contract unit price per cubic yard for Trench Excavation of Earth.

205

The accepted quantity of Drilling and Blasting Using Perimeter Control will be paid for at the Contract

unit price per cubic yard. Payment will be full compensation for clearing, grubbing, and removing

overburden prior to blasting; drilling, borehole profiling, loading of blastholes; performing blasting;

mucking and removal of the excavated rock; vibration and noise control; and for furnishing all labor, tools,

equipment, and incidentals to complete the work.

Payment for preparing and making required submittals will not be made separately but will be considered

incidental to the work under this section.

Payment will be made under:

Pay Item Pay Unit

205.1000 Drilling and Blasting of Solid Rock Subgrade .........................................Square Yard

205.2000 Drilling and Blasting Using Perimeter Control ........................................Cubic Yard

206

2-56SECTION 206 – ROCK SLOPE SCALING

206.01DESCRIPTION . This work shall consist of excavating loose and dilated rock on slopes. This work

includes high -angle construction to be completed via hand scaling using industrial rope access methods or machine scaling.

206.02SUBMITTALS . The Contractor shall submit to the Engineer the following information for

completing the work. Work shall not begin until the submittals have been approved in writing by the Engineer.

Contractor shall provide qualifications of Contractor’s personnel to the Engineer. The Contractor shall provide written evidence that the rock slope hand scaling foreman has a minimum of 5 years of demonstrated scaling experience as a foreman and rock slope hand scalers have a minimum of 2 years of demonstrated scaling experience. Operators for machine scaling shall have at least 1 year of demonstrated experience in machine scaling rock slopes.

a detailed work plan for each rock slope to be scaled. The plan shall include:

and qualified scalers in each crew.

the roadway from scaled rock.