ITEM
208 rock blasting
208.01
Description
208.02
Regulations on the Use of Explosives
208.03 Product
Specifications
208.04
Stabilization
208.05 Blasting
Plan Submittal
208.06
Production Holes
208.07 Blasting
Test Sections
208.08 Safety
Procedures
208.09
Presplitting
208.10 Cushion
(Trim) Blasting
208.11 Sliver
Cuts
208.12 Blaster
208.13 Blasting
Consultant
208.14
Pre-Blast Condition Survey
208.15
Vibration Control and Monitoring
208.16 Airblast and Noise Control
208.17
Hydrologist
208.18 Flyrock Control
208.19 Public
Meetings
208.20 Record
Keeping
208.21 Method
of Measurement
208.22 Basis of
Payment
208.01 Description. This work consists of using
production and controlled blasting techniques to fracture rock or shale and to
construct stable final rock cut faces.
Controlled
blasting refers to the controlled use of explosives and blasting accessories in
carefully spaced and aligned drill holes to produce a free surface or shear
plane in the rock along the specified excavation backslopes.
Controlled blasting techniques include presplitting, cushion (trim) blasting,
and sliver cut blasting.
If
the designed cut slope is steeper than 1:1 and deeper than 5 feet (1.5 m), use
controlled blasting techniques, even if the main excavation is ripped or
excavated. In rare instances, the Department will specify presplitting for 1 to
1 slopes. For all slopes that do not require controlled blasting techniques,
rake, excavate, hoe ram, or mechanically shape these slopes to obtain a neat
and smooth appearance.
Production
blasting refers to the rock fragmentation blasts resulting from more widely
spaced production holes drilled throughout the main excavation area adjacent to
the controlled blast line. Detonate production holes in a controlled
delay sequence.
208.02 Regulations on the Use of Explosives. Perform
all blasting operations according to all applicable Federal, State, and local
laws and regulations, and the provisions of 107.09.
These regulated blasting operations include but are not limited to the
following:
A.
Storage and handling of explosives, blasting agents, and detonators.
B.
Use of explosives in character and amount as allowed.
C.
Storage plan, including the type of magazine or explosive storage facility to
be used on the job site.
D.
Record keeping, placarding, safe distances, and all other requirements
concerning storage.
E.
Obtaining and displaying magazine permits.
208.03 Product Specifications. Be aware
that delay elements in blasting caps may deteriorate with age. Aged
explosives are known to deliver much less than the rated energy.
If
evaporation occurs or if improperly mixed, bulk explosives (such as ammonium
nitrate and fuel oil) may not contain the proper amount of diesel oil.
Low diesel oil drastically reduces the energy content of the explosive and
commonly produces reddish brown or yellow fumes upon detonation even in dry
blast holes.
Use
products conforming to manufacturers’ specifications. Ship the
manufacturer recommended expiration dates with the products delivered to the
project. Do not use any blasting product that is either excessively old
or in a deteriorated condition. Cease all work until the product’s age or
quality is determined.
208.04 Stabilization. Remove or stabilize rock
along the cut face that is loose, hanging, or creates a potentially dangerous
situation during or upon the completion of the excavation in each lift.
Do not drill the next lift until this work is performed.
208.05 Blasting Plan Submittal. Submit
three copies of the Blasting Plan to the Engineer and one copy of the Blasting
Plan to the Office of Construction Administration for review at least two weeks
before beginning drilling and blasting operations, or at any time the drilling
and blasting methods change. If the drilling and blasting methods change,
submit four copies of the changed sections one week prior to the work.
The
Blasting Plan shall include, at a minimum, the following:
A.
General details of the drilling and blasting patterns
and controls proposed to use for both the controlled and production blasting.
B.
Station limits of proposed shots. Critical distances to structures.
Place the pre-blast survey limits detailed in 208.14
on the Right-of-Way or plan view sheets.
C.
One plan and section view for each main excavation cut showing the proposed typical
range of drill patterns including a range of values for the free face, burden,
blast hole spacing, blast hole diameters, blast hole angles, lift heights, and subdrill depths.
D.
A typical loading diagram showing the type and amount of explosives, primers,
and initiators and location and depth of stemming.
E.
Typical range of initiator sequence of blast holes including delay times and
delay system.
F.
Manufacturers’ data sheets for all explosives, primers, and initiators to be
employed.
G.
Use the blaster’s plan form or the blasting plan forms in FHWA Publication FHWA-HI-92-001 Rock
Blasting and Overbreak Control. Adapt these
forms to meet the project requirements.
In
a subsequent submittal, submit one Detailed Plan for all test sections.
(Submit or fax at least 24 hours before the shot.) Detail the specific
proposed amounts of materials and work described in 208.05.A
through 208.05.G above
on this Detailed Plan.
The
Blasting Plan submittal is for quality control, informational, and record
keeping purposes. The review of the Blasting Plan does not relieve the
Contractor of the responsibility for using existing drilling and blasting
technology and for obtaining the required results.
If
specified in the Contract, use an approved blasting consultant, conforming to 208.13, to assist with the blast design and to ensure
that the Blasting Plan is carried out on the project.
208.06 Production Holes. Perform
all production blasting, including blasting carried out in conjunction with the
blasting test section requirements of 208.07,
according to the following requirements:
A.
Drill the production blast holes on the patterns and to the depths submitted in
the Blasting Plan and Detailed Plan, as specified in 208.05,
but not exceeding a depth of 60 feet (18 m). Drill the production blast
holes within two blast hole diameters of the staked
collar location. If the blaster does not drill the production holes then the
blaster shall inspect the holes and review the drilling logs prior to loading the
holes.
B.
Deepen or clean-out blast holes if they are plugged or unable to be fully
loaded. Check and measure blast holes before any explosives are loaded
into any of the holes to eliminate any safety hazard resulting from drilling
near loaded holes.
C.
Maintain a burden distance that is equal to or less than the bench height in
order to control the blasting effects.
D.
Drill the row of production blast holes immediately adjacent to the controlled
blast line on a plane approximately parallel to the controlled blast
line. Drill the production blast holes no closer than 6 feet (2 m) to the
controlled blast line. Drill the bottom of the production holes no lower
than the bottom of the controlled blast holes except by the amount of subdrilling used in the production holes. Do not
exceed 6 3/4 inches (170 mm) in diameter for the production blast holes. Delay
the detonation sequence of the production holes toward a free face.
E.
Maintain a stemming depth of at least 0.7 times the burden distance. If
water is present or when blasting within 200 feet (61 m) of a structure, use
crushed No. 8 coarse aggregate for holes less than 4 inches (100 mm) in
diameter and crushed No. 57 coarse aggregate for holes 4 inches (100 mm) in
diameter and larger for the stemming material. Use the coarse aggregate
gradations of Nos. 8 and 57 gradations on Table 703.01-1. If gravel is
used, use crushed material with a minimum of two mechanically fractured faces
on 60 percent of the material. In other locations, the Contractor may use
drill cuttings for stemming, if it does not compromise the shot integrity.
F.
Take all necessary precautions in the production blasting to minimize blast
damage to the rock backslope.
G.
Drill a line of buffer holes on a parallel plane adjacent to the presplit holes
if presplit results are not satisfactory and production holes are damaging the
presplit line. Drill the buffer hole 3 ± 1 inch (75 ± 25 mm) in
diameter. Drill the line of buffer holes approximately 3 feet (1 m) from
the presplit line, and space 3 to 5 feet (1 to 1.5 m)
center-to-center. Do not load the buffer holes with more than 50 percent
of the full explosive load that could be placed in a 3-inch (75 mm) production
hole. Delay the detonation sequence toward a free face.
208.07 Blasting Test Sections. Before
commencing full-scale blasting operations, demonstrate the adequacy of the
proposed Blasting Plan. Drill, blast, and excavate short test sections to
determine which combination of methods, hole spacing,
and charge works best. Use a test section with lengths up to 150 feet (45
m) for presplitting and 120 feet (36 m) for production blasting when field
conditions warrant.
Do
not exceed a production hole depth of 30 feet (9 m)
for the first test section.
Begin
the controlled blasting tests for presplitting with the controlled blast holes
spaced 36 inches (900 mm) apart, then adjust, if
needed, until the spacing for full-scale presplit blasting operations is
approved. A new test section is required to increase the spacing for the
presplitting to a maximum of 48 inches (1200 mm).
Perform
two test sections on every project. Use explosive depths greater than 20
feet (6.1 m) for these test sections. Use one test section for controlled
blasting and one test section for production blasting.
Apply
the requirements specified for controlled and production blasting operations to
the test section blasting.
For
controlled blasting and for production blasts within 10 feet (3 m) of the
finished slope, do not drill ahead of the test shot area until the test section
has been excavated and the results evaluated. If the test shots are
unsatisfactory, revise methods as necessary to achieve the required
results. Unsatisfactory test shot results include an excessive amount of
fragmentation beyond the indicated lines and grade, excessive flyrock, or violation of other requirements within Item 208.
If
the drilling and blasting methods do not produce the desired result of a
uniform slope and shear face, within the tolerances specified, drill, blast,
and excavate short sections, not exceeding 150 feet (45 m) in length for a
presplit line or 120 feet (36 m) for a production hole line, until a technique
produces the desired results.
The
blasting consultant shall witness the test sections drilling and loading
operations and be present when all test sections are shot. The time spent
witnessing these operations is considered part of the time required to observe
the loading, drilling, and blasting operations, as specified in 208.13.
A. Warnings and Signals. Establish a method of warning all employees on
the job site of an impending blast.
Define the limits of
the blasting area where there is a flyrock
danger. Control the access to the blasting area to prevent the presence
of livestock or unauthorized persons at least ten minutes before each blast.
Notify all employees
in the area that a blast shall be fired with a one minute signal. After the blast is over, sound an “all clear” signal so all
employees in the area understand that all blasting operations are finished.
One minute before the
blast, sound three long signals, lasting five seconds, on an air horn or
siren. For the all “clear” signal, sound one long signal, lasting at
least five seconds, to indicate that all blasting has ceased.
Fill out the
Department’s Blast Site Security Plan Form (CA-EW-11).
B. Lightning Protection. Furnish, maintain, and operate lightning
detection equipment during the entire period of blasting operations and during
the periods that explosives are used at the site. Use equipment similar
or equal to the Thomas Instruments SD250 Storm Alert as manufactured by DL Thomas Equipment, Keene, New
Hampshire. Install the equipment when approved. If the lightning
detection device indicates a blasting hazard potential, evacuate personnel from
all areas where explosives are present. If a lightning detector indicates
a blasting hazard, perform the following:
1.
Clear the blasting area of all personnel.
2.
Notify the Engineer of the potential hazards and precautions to be taken.
3.
Terminate the loading of holes and return the unused explosives to the day
storage area.
4.
If blast holes are loaded and would pose a hazard to traffic if detonated,
close the roads until the lightning hazard has passed.
5.
When the hazard dissipates, inform the Engineer that production blasting can
continue.
C. Check for Misfires. Observe the entire blast area for a minimum of
five minutes following a blast to guard against rock fall before commencing
work in the cut. The five minute delay between blasting and not allowing
anyone but the blaster to enter the area is needed to make sure that no
misfires have occurred.
During the five
minute delay, the blaster is responsible for going into the shot area and
checking all the holes to make sure that they have detonated. If any
holes have not fired, the blaster shall handle these misfires before others
enter the work area.
Halt the blasting
operations if the methods being employed result in the required slopes not
being in a stable condition or the safety and convenience of the traveling
public is jeopardized.
D. Misfire Handling Procedures. If a visual inspection indicates that complete
detonation of all charges did not take place, proceed as follows:
1.
If the system was energized and no charges fired for electric systems, test the
lead wire continuity before inspection of the remainder of the blast. For
nonelectric systems, check the lead in or tube to make sure that detonation has
entered the blast area.
2.
If an inspection of the electrical trunkline or lead
in tubing-line indicates that there is a break in the line or if the tubing did
not fire, repair the system and refire the
blast. If the inspection indicates that the trunkline
has fired, and misfired charges remain, the blaster shall do the following:
a.
Exclude all employees except those necessary to correct the problem.
b.
Close traffic, if a premature explosion could be a hazard to traffic on nearby
roads.
c.
Correct the misfire in a safe manner. If the misfire poses a problem that
the blaster cannot safely correct, the Contractor shall call a consultant or an
explosive company representative skilled in the art of correcting misfires to
correct the problem.
208.09 Presplitting. Perform all presplitting,
including that carried out in conjunction with the blasting test section
requirements of 208.07, according to the
following requirements:
A.
Completely remove all overburden soil and loose or decomposed rock along the
top of the excavation for a distance of at least 30 feet (9 m) beyond the end
of the production hole drilling limits, or to the end of the cut, before
drilling the presplitting holes.
B.
Remove potentially dangerous boulders or other material located beyond the
excavation limits.
C.
Drill the presplit holes 3 ± 1 inch (75 ± 25 mm) in diameter.
D.
Control the drilling operations by using proper equipment and technique to
ensure that no hole deviates from the plane of the planned slope by more than
12 inches (300 mm) either parallel or normal to the slope.
E.
Extend presplit holes a minimum of 30 feet (9 m) beyond the limits of the
production holes to be detonated, or to the end of the cut as applicable.
F.
Drill the presplit holes for any individual lift to a vertical depth of less
than or equal to 30 feet (9 m). Demonstrate that the blast can stay
within the above tolerances and produce a uniform slope. If more than 5
percent of the presplit holes are misaligned in any one lift, reduce the depth
of the lifts until the 12-inch (300 mm) alignment tolerance is met.
G.
If a cut height requires more than one lift or if there is a slope change (for
example, when changing from a 1:1 slope to a 0.75:1 slope), use a maximum
2-foot (0.6 m) offset between lifts for drill equipment clearances. Begin
the presplit blast hole drilling at a point that allows for the necessary
offsets and adjust to compensate for any drift that may occur in the upper
lifts. Move the controlled blast line back if required to accommodate for
these conditions.
H.
The Contractor may drill 2 feet (0.6 m) below ditch bottom to remove the toe
berm.
I.
Before placing charges, determine if the hole is free of obstructions for its
entire depth. Exercise all necessary precautions so that the placing of
the charges will not cause caving of material from the walls of the holes.
J.
Drill hole conditions may vary from dry to filled with
water. Use whatever types of explosives and blasting accessories
necessary to accomplish the specified results.
K.
Use a maximum diameter of explosives that is not greater than one-half the
diameter of the presplit hole.
L.
Do not use bulk ammonium nitrate and fuel oil (ANFO)
in the presplit holes.
M.
Use only standard explosives manufactured especially for presplitting in the
presplit holes.
N.
If using a continuous column cartridge type of
explosives with detonating cord, assemble and affix the detonating cord
according to the explosive manufacturer’s instructions. Furnish a copy of
the instructions to the Engineer.
O.
The Contractor may make the bottom charge of a presplit hole larger than the
line charges but not large enough to cause overbreak.
Place the top charge of the presplitting far enough below the collar, and
reduce the charge sufficiently, to avoid overbreaking
and heaving.
P.
Stem the upper portion of all presplit holes, from the topmost charge to the hole collar. Use stemming material conforming to the
stemming specified for the production holes in 208.06.
Q.
As long as equally satisfactory presplit slopes are obtained, either presplit
the slope face before drilling for production blasting or presplit the slope
face and production blast at the same time, provided the presplitting drill
holes are fired first. If required to reduce ground vibrations or noise,
delay the presplit holes, except that the hole-to-hole delay must be less than 25
milliseconds.
R.
Do not deviate the presplit slope face more than 1
foot (0.3 m) from a plane passing through adjacent drill holes, except
where the character of the rock is such that irregularities are
unavoidable. Measure the 1-foot (0.3 m) tolerance perpendicular to the
plane of the slope. Do not encroach on the roadbed with any portion of
the slope.
S.
Use the same diameter and drilled in the same plane and to the same tolerance
as the presplit holes when using unloaded and unstemmed
guide holes between presplit holes.
T.
Detonate the presplit line before detonating any production holes, except when
the closest horizontal distance between the production line and presplit line
is greater than 50 feet (16 m).
208.10 Cushion (Trim) Blasting. If the
horizontal distance from the cut face to the existing rock face is less than
15 feet (4.5 m), the Contractor may use cushion blasting instead of
presplitting. Perform cushion blasting according to 208.09, except as follows:
A.
Detonate along the cut face after the detonation of all production holes.
B.
Between the trim line and the nearest production row, use a difference in delay
time of 25 to 75 milliseconds.
208.11 Sliver Cuts. For sliver cuts, pioneering
the top of cuts and preparing a working platform to begin the controlled
blasting and drilling operations may require unusual working methods and use of
equipment. Use angle drilled holes or fan drilled holes during the
initial pioneering operations to obtain the desired rock face. Apply the hole diameter requirements for controlled blasting for
pioneering work. Do not exceed a hole spacing of
36 inches (900 mm).
208.12 Blaster. Use an experienced blaster in
charge of all blasting operations. Use a blaster with at least five years
of proven experience in heavy construction or highway rock blasting and with a
sufficient amount of proven experience of the type of highway rock blasting
required by the Contract.
Before
or at the preconstruction conference, submit a resume of the credentials of the
proposed blaster. Include in the resume a list of at least five heavy construction or highway rock blasting projects on which the
blaster was responsibly in charge of the rock blasting. List a description
of the projects, with details of the blasting operations. List the names
and telephone numbers of project owners with sufficient knowledge of the
projects to verify the submitted information. Obtain approval of the
blaster before beginning any drilling and blasting work. Allow 30 days
for the review of this documentation. The blaster shall perform the
following:
A.
Control the ground vibrations by the use of properly designed delay sequences
and by using allowable charge weights per delay.
B.
Base the allowable charge weights per delay on vibration levels that will not
cause damage.
C.
Establish the allowable charge weights per delay by carrying out trial blasts
and measuring the vibration levels.
D.
Independently measure the vibrations and airblast at
the closest structure using the criteria and limits set in 208.15 and 208.16.
Ensure that only trained and certified personnel set up the seismographs.
E.
Use appropriate blast hole patterns, detonation
systems, and stemming to prevent venting of blasts and to minimize airblast and noise levels produced by the blasting
operations.
F.
Carry out the trial blasts according to the blasting test section requirements
of 208.07.
G.
Report the vibrations (velocity and frequency) and airblasts
on both seismographs before the next blast. This report shall denote
whether or not these numbers exceeded the allowable set by the vibration
specialist.
H.
Modify 208.12.A through 208.12.F above as
required to limit ground vibrations and airblast to
the levels established by the vibration specialist, and the airblast
and noise control specialist.
I.
Coordinate and review the blast hole layout and
drilling operations.
The
blaster, blasting contractor, or the Contractor shall obtain insurance as
specified in 107.12. Present a certificate of insurance 10 days
before the blasting operations begin.
208.13 Blasting
Consultant. If specified in the Contract, retain an
experienced and recognized blasting consultant to assist in the blast
design. The blasting consultant shall
assist in the design of both the controlled and production blasting.
Retain
a blasting consultant with at least five years of proven experience in heavy
construction or highway rock blasting design and with a sufficient amount of
proven experience of the type of highway rock blasting design required by the
Contract. The Contractor shall not use a
blasting consultant that is an employee of the Contractor, explosives
manufacturer, or explosives distributor.
Before
or at the preconstruction conference, submit a resume of the credentials of the
proposed blasting consultant. Include in
the resume a list of at least five heavy construction
or highway rock blasting projects on which the blasting consultant was
responsibly in charge of the rock blasting design. List a description of the projects, with
details of the blast plans and modifications made during the project. List the names and telephone numbers of
project owners with sufficient knowledge of the projects to verify the
submitted information. Obtain approval
of the blasting consultant before beginning any drilling and blasting
work. Allow 30 days for the review of
this documentation.
The
blasting consultant shall observe the loading, drilling, or blasting operations
for at least 8 hours per week if these operations are in progress for 40 or
more hours per week. The blasting
consultant shall witness the drilling, loading and blasting of the first shot
in each major cut. At a minimum, the blasting
consultant shall witness the drilling, loading and blasting of every 20th shot
on the project. The blasting consultant
shall write a written report to the Engineer at least once a month detailing
the blasting operations. The time spent
writing this report is not considered part of the time required to observe the
loading, drilling, and blasting operations.
The Contractor shall coordinate the blasting consultant’s hours with the
Engineer.
208.14 Pre-Blast
Condition Survey. If specified in the Contract, conduct a
pre-blast survey of any buildings, structures, or utilities within 1500 feet
(460 m) or to the nearest structure up to a 1/2-mile (0.8 km) radius of the
blasting operations. Use a greater
radius if the structures are potentially at risk from blasting damage. The Contractor shall use a survey method
acceptable to its insurance company. The
Contractor is responsible for any damage resulting from blasting.
If
owners or occupants fail to allow access to the property for the pre-blast
survey, send a certified letter to the owner or occupant. Make the notification effort and the
certified letter part of the pre-blast survey records.
Submit
a copy of the pre-blast survey records to the Engineer before beginning the
blasting operations at the critical blasting locations.
Notify
occupants of local buildings before the commencement of blasting.
208.15 Vibration
Control and Monitoring. If specified in
the Contract, use vibration control and monitoring if blasting near buildings,
structures, or utilities that may be subject to damage from blast induced
ground vibrations. The vibration
specialist interprets the seismograph records to ensure that the seismograph
data is effective in the control of the blasting operations with respect to the
existing structures.
Retain
an experienced vibration specialist to establish the safe vibration
limits. Use a vibration specialist with
at least five years of proven experience in monitoring vibrations on heavy
construction or highway rock blasting projects and with a sufficient amount of
proven experience of the type of highway rock blasting vibration monitoring
required by the Contract.
Use
a vibration specialist that is an expert in the interpretation of the vibration
data. The Contractor shall not use a
vibration specialist that is an employee of the Contractor, explosives
manufacturer, or explosives distributor.
Before
or at the preconstruction conference, submit a resume of the credentials of the
proposed vibration specialist. Include
in the resume a list of at least five heavy construction
or highway rock blasting projects on which the vibration specialist was responsibly
in charge of monitoring the rock blasting vibrations. List a description of the projects, with
details of the vibration interpretations made on the project. List the names and telephone numbers of
project owners with sufficient knowledge of the projects to verify the
submitted information. Obtain approval
of the vibration specialist before beginning any drilling and blasting
work. Allow 30 days for the review of this
documentation.
The
vibration specialist shall perform the following:
A. Monitor each blast with an approved
seismograph located between the blast area and the closest structure subject to
blast damage.
B. Use a seismograph capable of recording
particle velocity for three mutually perpendicular components of vibration in
the range generally found with controlled blasting.
C. Furnish the data recorded for each shot
before the next blast and include the following:
1. Identification of instrument used.
2. Name of approved observer and
interpreter.
3. Distance and direction of recording
station from blast area.
4. Type of ground at recording station and
material on which the instrument is sitting.
D.
Ensure that the peak particle velocity of each component of the safe
limits of the nearest structure subject to vibration damage is not exceeded.
E. The vibration specialist may elect to
summarize and report this information monthly, when the blaster measures the
vibration and airblast with its own seismograph and
reports the measurements on the vibration specialist’s seismographs.
F. Establish what vibration limits are being
used and explain why they are being used to the Engineer before blasting begins
near structures denoted in the pre-blast survey in 208.14.
G. Stop all operations if the vibration
limits are exceeded until the vibration specialist reports to the Engineer that
no damage has occurred or will occur and that corrective action has been taken
to lower the vibration.
208.16 Airblast
and Noise Control. If specified
in the Contract, install an airblast monitoring
system between the main blasting area and the nearest structure subject to
blast damage or annoyance.
Retain
an experienced airblast and noise control
specialist. Use an airblast
and noise control specialist with at least five years of proven experience in airblast and noise control on heavy construction highway
rock blasting projects and with a sufficient amount of proven experience of the
type of rock blasting airblast and noise control
monitoring required by the Contract. Use
an airblast and noise control specialist that is an
expert in airblast and noise control. The Contractor shall not use an airblast and noise control specialist that is an employee
of the Contractor, explosives manufacturer, or explosives distributor.
Before
or at the preconstruction conference, submit a resume of the credentials of the
proposed airblast and noise control specialist. Include in the resume a list of at least five
heavy construction or highway rock blasting projects
on which the airblast and noise control specialist
was responsibly in charge of the airblast and noise
control of the rock blasting operations.
List a description of the projects, with details of the airblast and noise control monitoring made on the
project. List the names and telephone
numbers of project owners with sufficient knowledge of the projects to verify
the submitted information. Obtain
approval of the airblast and noise control specialist
before beginning any drilling and blasting work. Allow 30 days for the review of this
documentation.
The
airblast and noise control specialist shall perform
the following:
A. Use equipment of the type specifically
manufactured for the purpose to make the airblast
measurements. Hold peak overpressure
below 134 dB at the nearest structure or other designated location. Lower the overpressure limit if it proves too
high based on damage or complaints.
B. The airblast
and noise control specialist may establish the peak overpressure limits higher
than 134 dB.
Submit information explaining why higher limits are needed and are safe
to the Engineer before blasting begins near structures denoted in the pre-blast
survey in 208.14.
C. Furnish a permanent signed and dated
record of the peak overpressure measurements to the Engineer immediately after
each shot or use the same reporting procedures and time frames denoted for
vibration in 208.15.
D. Stop all operations if the overpressure
limits are exceeded until the airblast and noise
control specialist reports to the Engineer that no damage has occurred or will
occur and that corrective action has been taken to lower the airblast.
208.17 Hydrologist.
If specified in the Contract, use a qualified
hydrologist to monitor before, during, and after blasting or major excavation
the quantity and quality of the water supplies within 1500 feet (460 m) of the
blasting or major excavation areas. The
water supplies shall include, but not be limited to, all wells, springs, or
other water supplies for human consumption.
Retain
an experienced hydrologist. The
Contractor shall not use a hydrologist that is an employee of the Contractor,
explosives manufacturer, or explosives distributor.
Before
or at the preconstruction conference, submit a resume of the credentials of the
proposed hydrologist. Include in the
resume a list of at least five heavy construction or highway projects on which
the hydrologist was responsibly in charge of monitoring water quality and
quantities. List a description of the
projects, with details of the water monitoring or modeling performed on the
projects. List the names and telephone
numbers of project owners with sufficient knowledge of the projects to verify
the submitted information. Obtain
approval of the hydrologist before beginning any major excavation, drilling, or
blasting work. Allow 30 days for the
review of this documentation.
The
hydrologist shall perform, at minimum, all of the following:
A. Review the available public records,
including Ohio DNR well logs, to obtain background
information and to identify the locations and geology of water supplies within
1500 feet (460 m) of the blasting areas or major excavations.
B. Examine private wells, and public and
industrial water supplies (as allowed by property owners or occupants), and
measure water levels and well depths with a water level meter. Clean the water level meter before and
between each use.
C. Collect water quality data (pH, e-coli,
specific conductivity, turbidity, sulfur, and iron) from private wells, and
public and industrial water supplies to determine the major excavation work or
blasting effects on the water supplies by using field instruments.
D. Measure the water quality and water level
for a minimum of two times per week for two weeks before, during, and two weeks
after major excavation or blasting within 1500 feet (460 m) of the water
supplies.
E. Perform an associated field survey of the
locations and elevations of wells and springs.
F. Evaluate the need for piezometers to
monitor the ground water conditions.
Place and monitor the piezometers as necessary.
G. Provide a monitoring plan report
detailing the proposed activities, frequencies, testing, and any
recommendations for monitoring the water supplies as detailed in 208.17.A through 208.17.F
above. Submit this report at least 10
days before beginning the scheduled blasting or major excavation.
H. Provide a monthly report of the
conclusions and results of the monitoring plan.
I. Provide a final report on the final
condition or effect of the blasting or major excavation on the water
supplies. Submit this report within 30
days after the blasting or major excavation is completed on the project.
J. Meet with the Engineer in order to
coordinate this work and provide input, update the project schedule, report
progress (including completed work and updated schedule), and make
recommendations. Allow for ten meetings.
The
Contractor is not responsible for damages to the above denoted water supplies
if the blasting or excavation is done according to this specification. The Contractor is responsible for damage
caused by negligence, vibration or noise above the allowable limits, flyrock, or back break.
208.18 Flyrock
Control. Before firing any blast in areas where flying
rock may result in personal injury or unacceptable damage to property or the
work, cover the rock with blasting mats, soil, or other equally serviceable
material to prevent flyrock.
If
flyrock leaves the construction site or lands on a
traveled road, the Contractor shall cease all blasting operations until the
blasting consultant specified in 208.13 reviews
the site and determines the cause and solution to the flyrock
problem. Before blasting proceeds,
submit a written report addressing the following:
A. Why the flyrock
left the construction site or landed on a traveled road.
B. What corrective measures were taken to
prevent this from reoccurring?
208.19 Public
Meetings. If a blasting consultant, vibration
specialist, airblast and noise control specialist, or
hydrologist are specified in the Contract, make the
consultant, specialists, Contractor’s superintendent and blaster available for one
day to prepare for and participate in a public meeting organized by the
Engineer and conducted by the Contractor to inform the public about anticipated
drilling and blasting operations. The
consultant and specialists shall be prepared to answer any questions dealing
with the magnitude of seismic motion, vibrations, airblast
overpressure, flyrock, and water problems that may
affect the public.
A. Daily Explosive Material
Consumption. Keep a daily record of the
transactions at each storage magazine.
Update inventory records at the close of every business day. Show on the records the class and quantities
received and issued and total remaining on hand at the end of each day. Check the remaining explosive inventory each
day and report any discrepancies that would indicate a theft or loss of
explosive material.
B. Report of Loss. If a loss or theft of explosives occur,
report all circumstances and details of the loss or theft immediately to the
nearest Bureau of Alcohol, Tobacco and Firearms, as well as to the local law
enforcement authorities and the Engineer.
C. Daily Drilling and Blasting Logs. On a weekly basis, provide a daily log of the
drilling and blasting operations. Update
the log at the close of each business day.
Fill
out the Department or blaster’s drilling form to document the following:
burden, spacing, bench height, hole depth and
diameter, and subdrill depth. Document additional
information about the drilling such as voids, mud seams, air pressure loss and
lack of cuttings. The driller
shall give this form to the blaster and the Department.
Document
on the blasting log the number of blasts, times and dates of blasts, the
blasting locations and patterns, and all of the following information:
1. Station limits of the shot.
2. Plan and section views of drill pattern
including free face, burden, blast hole spacing, blast hole diameters, blast
hole angles, lift height, and subdrill depth.
3. Loading diagram showing type and amount
of explosive, primers, and initiators and location and depth of stemming.
4. Initiators sequence of blast holes
including delay times and delay system in each blast hole.
5. Trade names and sizes of all explosives,
primers, and initiators employed.
6.
Signature of the blaster in charge.
7. Use the blaster’s blasting form or the
Blasting Report form in FHWA
Publication FHWA-HI-92-001 Rock Blasting and Overbreak
Control. Adapt these forms to meet the
project requirements.
The
drilling and blasting logs are for quality control, informational, and record
keeping purposes. Review of the blast
log by the Engineer does not relieve the Contractor of responsibility for the
accuracy and adequacy of the drilling and blasting log.
D. Video Recording of Blasts. Record video of each blast. Index the recordings in a manner that permits
easy and correct identification of each blast.
Submit copies of the blast recordings on a
weekly basis. If submitting the video
recordings as electronic data files, furnish them in a video format acceptable
to the Engineer and capable of being viewed on the Department’s computers.
208.21 Method
of Measurement. The Department will measure Presplitting by
the number of square yards (square meters) along the slope face of the
cut. The horizontal measurement will
begin at the first hole and end at the last hole of the cut, and the vertical
slope measurement will be along the sloped drill hole.
208.22 Basis
of Payment. The Department will not make separate payment
for the production blasting operations.
Payment for the production blasting is incidental to the other work
items in the Contract requiring blasting.
The Department will pay for additional excavation volume resulting from
the 2-foot (0.6 m) offsets at the Contract unit price for Item 203
Excavation. The Department will pay
for the removal of this material beyond the excavation limits under 109.05.
The
Department will pay lump sum for all work for the Pre-Blast Condition Survey,
Blasting Consultant, Airblast and Noise Control,
Vibration Control and Monitoring, and Hydrologist. The same person or consultant may perform the
pre-blast survey, vibration control and monitoring, airblast
and noise control, and the work required of the hydrologists. The Department may make intermediate payments
based on the percentage of the work completed for Pre-Blast Condition Survey,
Blasting Consultant, Airblast and Noise Control,
Vibration Control and Monitoring, or Hydrologist.
Payment
for guide holes is incidental to Presplitting.
Payment for all of controlled blasting is included in the payment for
Presplitting.
The
Department will pay for stabilization under 109.05
if caused by geology. The Department
will not pay for stabilization if caused by the Contractor’s blasting
operations.
The
Department will pay for the placement and monitoring of piezometers according
to 109.05.
The
Department will pay for accepted quantities at the contract prices as follows:
Item Unit Description
208 Square Yard Presplitting
(Square Meter)
208 Lump Sum Pre-Blast Condition
Survey
208 Lump Sum Blasting Consultant
208 Lump Sum Airblast
and Noise Control
208 Lump Sum Vibration Control and
Monitoring
208 Lump Sum Hydrologist