204.01 Description
This work is using blasting techniques to form cut slopes, remove rock obstructions and other objects to construct highway roads, bridges, and facilities.
204.02 Material
Furnish non-plastic crushed granular material for stemming, meeting the following gradation requirements: Sieve Size Percent Passing ⅝ʺ (16 mm) 100 No. 4 (4.75 mm) 0 – 10 Provide a minimum of 35% of the material retained on the No. 4 (4.75 mm) sieve with at least one fractured face.
204.03 Production Blasting
Production blasting refers to the main fragmentation blasting resulting from more widely spaced production holes drilled throughout the main excavation area adjacent to the controlled blast line.
204.03.1 Blasting Professional
A.Blasting Consultant. Retain a recognized independent Blasting Consultant to assist in the blast design. Ensure the Blasting Consultant is an expert in the field of drilling and blasting and is not an employee of the Contractor, blaster, driller, other subcontractor, an explosives manufacturer, or explosives distributor. Review the Blasting Consultant’s resume to ensure adequate experience in drilling and blasting. Submit the resume at the Pre-Construction Conference. The Blasting Consultant is professionally responsible when advising the Contractor on issues relating to blast safety, blast design, and public safety and convenience. The Contractor is responsible for all damage. The Blasting Consultant is the responsible charge for the blast monitoring, pre-blast and post-blast surveys, ground vibration monitoring, and air overpressure monitoring. Have the Blasting Consultant review all blasting plans and submit comments regarding the adequacy of the blast plans to ensure conformance to these specifications and all other applicable Federal, State, and local regulations. The Blasting Consultant and the Blaster-in-Charge must coordinate their efforts to ensure these requirements are met. Forward the Blasting Consultant’s comments, Master Blasting Plan, and all other ancillary plans required by the contract for review. The Blasting Consultant has the authority to require modification of any of the proposed blasting plans to meet project requirements, environmental requirements, or satisfy safety concerns. Submit these modifications for review as required. The Blasting Consultant must attend all blasting related meetings including the preconstruction meeting.
B.Prequalified Blasting Contractors. Use prequalified blasting contractors to complete the work required in the contract. A list of prequalified contractors is located at the following website: http://www.mdt.mt.gov/business/contracting/prequalified.shtml . Contractors not currently pre-qualified by the Department to perform blasting work can obtain pre-qualification information from the CES Bureau, 2701 Prospect Ave., 204 – BLASTING 2020 EDITION V5.1 204-2 Helena, Montana. A complete Statement of Qualifications (SOQ) must be received a minimum of 14 calendar days prior to the bid opening as specified in the Invitation for Bids.
204.03.2 Use of Explosives
Explosives refer to any commercial explosive products, materials, blasting agents, primers, delays, initiators, etc., used in blasting operations. Transport, store, handle, and load explosives and blasting agents following all laws and ordinances as well as the applicable requirements of Title 29, Title 30, and Title 49 of the Code of Federal Regulations and specifically the current Office of Surface Mining Reclamation and Enforcement (OSMRE) Blasting Guidance Manual when using, handling, loading, transporting, and storing explosives and blasting agents. Use only explosives permitted by the State, local laws and ordinances, and all respective agencies having jurisdiction over them. Use explosives without endangering life or property and be responsible for all resulting property damages, injury, or death. Only use persons experienced in the handling of explosives and do not fire explosives until sounding a warning and removing all persons from the radius of danger. Notify each property owner, Railway Company, and public utility Company having facilities near the blasting area of the intent to use explosives to enable them to take precautions to protect their property from injury. Be responsible for damage to property or injury to persons attributable to the use of explosives. Do not use explosives and explosive products containing the chemical compound perchlorate (ClO 4).
204.03.3 Master Blasting and Safety Plan
Submit a Master Blasting and Safety Plan on form MDT-CON-204-03-3, along with any comments from the Blasting Consultant, for review or at any time the drilling and blasting methods, or explosive type or product are changed. Include full details of the drilling and blasting patterns and controls to be used for production blasting in the blasting plan.
A.Blasting Plan. Include the following information, at a minimum, in the blasting portion of the plan:
1.Shot Number.
2.Date and proposed time of shot.
3.Top and bottom elevations of the blast.
4.Seismograph locations, elevations, and distances between the blast and vibration monitoring points.
5.The station limits of the proposed blast(s) and the number of holes to be drilled and shot per blast.
6.The hole diameter, hole depths, and explosive load for each hole (number of cartridges of each type, stemming depth, decks, and primers, etc.).
7.Explosive type; diameter; length; weight; and brand name.
8.Proposed quantities of production and presplit/cushion blasting for each blast and the entire project.
9.Appropriately scaled plan diagram(s) showing blast hole locations, blast hole diameter, blast hole pattern, blast hole angle(s), free face, burden, spacing, lift height, sub drill depth(s), delay periods, delay pattern, and relative location of nearby 2020 EDITION V5.1 BLASTING – 204 204-3 structures and appurtenances. Base all plan diagrams on the project plan sheets, including topography.
10.Appropriately scaled cross section diagram(s) showing blast hole depths, blast hole angle(s), loading, stemming, sub drill (as applicable), etc. Base all cross-section views on the project plan sheets, including topography.
11.Total pounds of explosives and number of cartridges to be used.
12.Total volume of blasted material.
13.Powder Factor and maximum pounds of explosives per delay.
14.Detailed calculations for predicted peak particle velocities and predicted vibration frequencies for ground and pertinent adjacent structures to ensure compliance with required peak particle velocity and vibration limits.
15.The signatures of the Blaster-in-Charge and the Blasting Consultant.
16.A storage plan for explosives, including the type of magazine or explosive facility, (if applicable) or a declaration indicating the use of daily explosive deliveries for the duration of the project. Provide a copy of the notification letter sent to the Federal Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF), signed by the magazine owner, if daily delivery will not be utilized at any time during the contract.
17.A detailed plan with the methods describing fly rock or blast debris prevention.
18.Manufacturer’s product data sheets or technical bulletins and MSDS information for all explosives to be employed.
19.Copies of the Blaster-in-Charge’s current State of Montana Blasters License. The State of Montana requires blasters to have a current Montana Blasters License. The Master Blasting Plan and required submittals will be reviewed and revised based on the results of the test blasts. After satisfactorily completing the test blast section(s) and incorporating all test blast results and Blasting Consultant’s comments, submit the reviewed and revised blasting plan as the Master Blasting Plan. Submit an individual production blast plan for all subsequent blasts at least 4 business days prior to the planned blast day. Include the items discussed above, in Subsection 204.03.3(A) , items (1) through (15), in each blast plan. Submit the production blasting plans on form MDT- CON-204-03-3A. Do not begin full scale production blasting until the master blast plan has been submitted and reviewed for conformance to the Contract. Review of the blast plan(s) does not relieve the Contractor of responsibility for the accuracy, adequacy, and safety of the plan when implemented in the field.
B.Safety Plan. Include the following information, at a minimum, in the Safety portion of the plan:
1.The name and telephone number of the Blaster-in-Charge. The Blaster-in-Charge is responsible for directing the day-to-day drilling and blasting operations, for clearing the blast site before excavation of the blasted material may proceed, for clearing local traffic through the blast zone, and for all required report preparation including daily blast logs, daily explosives consumption reports, and loss reports. Submit sample copies of daily blast logs, daily explosives consumption reports, and loss reports.
2.A detailed access control plan with the methods proposed to clear the blast area and to control access to the blast site and other closure locations required by the contract by unauthorized personnel during drilling, loading, blasting, and scaling operations. This plan will be followed exclusively by all parties concerned.
3.A detailed plan with the methods proposed to notify local residents, and all project personnel involved with field operations within the blast area, of an impending blast. Include the method(s) of notification and the proposed timeline(s) in the plan. 204 – BLASTING 2020 EDITION V5.1 204-4
4.A detailed plan with methods to document, assess, and control ground vibration and air overpressure as well as calculated scale distances to each structure or appurtenance within a minimum of 1,320 feet (400 m) from the blast. Structures and appurtenances include, but are not limited to culverts, bridges, other drainage facilities, wells, gabion walls, bin walls, other retaining structures, utilities, buildings, residences, railroads, etc.
5.A detailed vibration and blast monitoring plan, including a current calibration certification of any seismographs to be used.
6.A detailed fire prevention and protection plan.
7.A detailed plan to identify all potential blast site electrical hazards including, but not limited to, a lightning detection and protection plan.
8.A detailed emergency plan outlining the procedures to be followed in the event of an injury, accident, or unanticipated road closure in excess of one hour. Details of this plan must contain provisions for emergency vehicle traffic and personnel including potential detour routes, length of emergency detour, and estimated time to traverse the emergency detour.
9.A detailed blasting day protocol to be followed by all parties concerned. Information in the blasting day protocol must include, but is not limited to:
a.Notifications made to impacted local residents, all project personnel, local emergency response organizations, utilities, or other entities that may be impacted by the blast.
b.A contact list and appropriate phone numbers of all parties impacted by or involved in the blasting. Post the contact list in the field office and submit list to the Project Manager.
10.A copy of a sign-up sheet documenting attendance of mandatory safety meetings by all project personnel involved with field operations within the blasting area.
11.A detailed scaling plan including the methods proposed and the entity responsible for conducting scaling operations on the project.
12.The signature of the Blaster-in-Charge and the Blasting Consultant. Blasting and Safety Plan submittals must be complete. They may be submitted as 2 separate submittals, but each plan must be a complete document. The review time does not start until the complete package is received. Electronic documents (.pdf) are encouraged but may also be in the form of portable storage devices.
204.03.4 Blasting Test Section(s)
Prior to conducting full-scale blasting operations, demonstrate the adequacy of the proposed Master Blasting Plan by drilling, blasting, and excavating test sections 100 feet (30 m) in length. Use the test sections to demonstrate which combination of methods, burden, spacing, other blast design parameters, and charge perform the best based on in-situ field conditions. When warranted by field conditions, test sections shorter than 100 feet (30 m) may be required, as determined by the Project Manager. Requirements for production blasting operations covered elsewhere in this specification also apply to the blasting operations carried out in conjunction with the test blasts. Do not drill ahead of the test blast area until the test section has been excavated and the results are evaluated by the Project Manager. If the results of the test blast(s) are unsatisfactory, adopt revised methods as necessary to achieve the required results at no additional cost to the Department. If methods of drilling and blasting do not produce a uniform slope and shear face or adequate fragmentation within the tolerances specified in the contract, drill, blast, and excavate in short 2020 EDITION V5.1 BLASTING – 204 204-5 sections, not exceeding 100 feet (30 m) in length, until a technique is arrived at producing the desired results, with no additional cost to the Department. Unsatisfactory blast results include but are not limited to fragmentation beyond the indicated lines and grade (over break), excessive oversize material, poor fragmentation, fly rock, excessive ground vibration, excessive air overpressure, or violation of other requirements within these specifications. All costs incurred in adopting revised blasting methods necessary to produce an acceptable test blast are the sole responsibility of the Contractor.
204.03.5 Safety
Comply with all State and Federal requirements for blasting safety, including the OSMRE Blasting Guidance Manual, which provides guidance on the use of explosives and certification of blasters.
A.General. Prior to each blast, conduct a safety meeting to discuss the safety requirements for blasting operations and the blast day protocol. Attendance for this meeting is mandatory for all project personnel that may be involved in field operations within the blasting and closure areas. Document attendance with a sign-up sheet and provide a copy of this sheet to the Project Manager. If there any changes to the safety requirements or blast day protocol, conduct another mandatory meeting and document attendance as required above.
1.Post required blasting signage prior to the start of the shift on the day of the blast. Signage must meet requirements of Section 618 and the traffic control plan.
2.Do not blast during hours of darkness (one-half hour before sunset to one-half hour after the following sunrise).
3.Do not load holes during hours of darkness (as defined above).
4.Do not load explosives prior to Department review of applicable blast plans.
5.Keep all personnel and equipment not involved in loading or blasting operations a minimum of 100 feet (30 m) from the blast site during loading operations.
6.Keep all equipment and personnel a minimum of 1,000 feet (305 m) from the blast site during blasting operations.
7.Remove and properly dispose of all explosives packaging material prior to each blast.
B.General. The blasting day protocol is to be followed exclusively by all parties concerned. Information in the blasting day protocol includes, but is not limited to, the information listed in Subsection 204.03.3(B)(9) .
1.Convene the following personnel one hour prior to blasting to coordinate traffic control, required closures, and blast procedures: Blasting Consultant, Blaster-in- Charge, Traffic Control Contractor, Project Manager (or Representative), Contractors or Subcontractors Foreman, and other pertinent personnel.
2.Road closures due to blasting operations and clean-up may not exceed the requirements of the contract. Clean-up activities include, but are not limited to, scaling or clean-up of loose rock or blasting related debris for safety purposes.
3.If road closures due to blasting operations exceed the required time limit, the Project Manager will suspend all work not directly related to blasting activities in accordance with the following:
a.Closures up to 15 minutes beyond the allowed closure will result in a 2-day suspension of all work as defined above and time charged to the contract.
b.Closures of 15 to 30 minutes beyond the allowed closure will result in a 3-day suspension of all work as defined above and time charged to the contract.
c.Closures of greater than 30 minutes beyond the allowed closure will result in a 4- day suspension of all work as defined above and time charged to the contract. 204 – BLASTING 2020 EDITION V5.1 204-6
d.The Project Manager will rescind the suspension of work after receipt of a written plan from the Contractor detailing the measures to be taken to ensure compliance with the required road closure times. No adjustment to contract time will be made for work suspensions resulting in excessive road closures.
C.Warnings and Signals. Provide a detailed explanation and description for the signals that will be used. The warning signals must be clearly audible for ½-mile (800 m) from the blast site. The Blaster-in-Charge must demonstrate to the Project Manager that the method of warning meets this requirement.
1.Sound an initial warning signal 5 minutes prior to blast initiation to notify all in the area of the start of blasting within a 5-minute period. Sound a second warning signal one minute prior to blast initiation.
2.After the blast is over, the Blaster-in-Charge and the Blasting Consultant are required to observe the entire blast area for a minimum of 5 minutes to determine if all explosives have detonated and to guard against rock fall before commencing cleanup work and excavation.
3.The Blaster-in-Charge is responsible for clearing the site. If any holes have not detonated, the Blaster-in-Charge, with the assistance and advice of the Blasting Consultant, is required to address the misfire(s) and eliminate the hazard before other personnel enter the worksite. The blast site is off limits to unauthorized personnel during this time. The Contractor is responsible for all costs resulting from misfires. If a misfire occurs on a blast, notify the Project Manager. Submit a written report of existing conditions and remedial action taken within 24 hours.
4.Once the Blaster-in-Charge and the Blasting Consultant indicate the area is free from misfires, blast damage, overhangs, or other hazards, sound an all-clear signal to indicate to all personnel in the area that blasting operations are finished. Do not allow traffic to proceed until the all-clear signal is given.
204.03.6 Pre-Splitting Rock Slopes
A.General. Pre-split rock cuts to a smooth plane using loaded, timed, and spaced drill holes. Produce a continuous or semi-continuous fracture between drill holes and a stable rock cut by eliminating over break in the back slope during primary blasting.
B.Drilling. Use drills equipped with mechanical devices that accurately determine the angle the drill steel enters the rock. Do not drill if the devices are missing or inoperative. Perform grading, as necessary, to remove overburden soil and loose or decomposed rock along the top of the excavation to establish a uniform and stable platform for drilling activities. Use pre-split hole diameters that are between 2½ and 3 inches (65 to 75 mm). Drill pre-split holes within 3 inches (75 mm) of the staked collar location. Holes drilled outside the 3-inch (75 mm) tolerance will be rejected and not measured for payment. Drill hole intervals may vary between 24 and 36 inches (610 to 915 mm). A 30-inch (765 mm) interval is used to estimate the quantity of pre-split drilling in the contract. When the cut height exceeds 30 feet (10 m), and after completion of the top excavation lift, an offset from the staked slope line, not to exceed 2 feet (610 mm) is allowed at the top of each lift after the top lift. The actual slope cannot deviate from the plan slope by more than 1-foot (305 mm). Control the drilling operations to ensure that no hole deviates from the slope plane by more than 9 inches (230 mm). This tolerance applies to deviations left or right of an apparent vertical 2020 EDITION V5.1 BLASTING – 204 204-7 projection of the hole when viewed from a right angle to the slope face or deviations into or out of the planned slope plane when viewed parallel to the slope face. Pre-split holes exceeding these limits will not be paid for. Drilling 2 feet (610 mm) below ditch bottom to aid in removing the toe berm is permitted. Extend pre-split holes a minimum of 30 feet (9.1 m) beyond the limits of the production holes or to the end of the cut. Maintain the length of pre-split holes for any individual lift at no more than 30 feet (9.1 m). The Project Manager may approve a written request to increase the hole length to a maximum of 60 feet (18.2 m) if it is demonstrated that the above pre-split hole tolerances and a uniform slope can be maintained. If over 5% of the pre-split holes are misaligned in any one lift, reduce the lift heights until the 9-inch (230 mm) tolerance is met.
204.03.7 Blasting Operations
A.General. All blasting operations, including the transport, storage, handling, and loading of explosives, are the direct responsibility of the Blaster-in-Charge. Conduct all blasting operations in accordance with the contract and all applicable Federal, State, and local regulations. Store all explosives in accordance with the submitted storage plan and all applicable Federal, State, and local regulations. Provide each cap period from one lot number. Mixing of lot numbers for any one cap period is prohibited. Any blasting materials in excess of one year of age are prohibited. If any explosives are determined to be of either excessive age or in a deteriorated condition, cease all blasting work until the explosives age or quality can be verified. Do not use explosives that do not meet the manufacturer’s specifications. Remove and properly dispose of explosives, not meeting the manufacturer’s specifications, at no cost to the Department. Explosives missing date codes are prohibited and cannot be brought to the site. The Blasting Consultant is responsible for verifying that the above requirements are met. The Project Manager has the authority to: • Require the explosives to be tested by an independent organization to determine its performance compared to the manufacturer’s product data sheet. • Approve the independent testing organization prior to performing the tests. • Reject any lot number if the explosives performance and/or composition deviates more than 10% in any manner from the manufacturer’s product data sheet. All costs for testing and replacement of the explosives are the Contractor’s responsibility if the explosives’ performance or composition deviates by more than 10%. The Department will pay the testing costs if the explosives meet the manufacturer’s product data sheet.
B.Procedure. Drill production blast holes in accordance with the patterns shown on the submitted blasting plan(s). Drill the production blast holes within two blast-hole diameters of the staked collar location. Do not drill the production hole bottoms lower than the presplit hole bottoms. The maximum allowable diameter for production holes is 6 inches (150 mm). Locate and stake the blast holes. If more than 5% of the holes are drilled outside of this tolerance, fill the holes with crushed stone or approved material and re-drill the blast holes at the proper location. 204 – BLASTING 2020 EDITION V5.1 204-8 Detonate production holes on a delay sequence toward a free face. Stem production holes a minimum of 3 feet (915 mm) or 0.7 times the burden distance, whichever is greater, with stemming meeting the requirements of this specification. Take all precautions necessary in the blasting operations to prevent blast damage to the final rock slope. Production blasting is incidental to and included in the measurement and payment for unclassified excavation. Do not use bulk ammonium nitrate and fuel oil in the pre-split holes. Use only standard explosives manufactured specifically for pre-splitting. Fit blast holes with a temporary plug to prevent overburden, drill cuttings, or other foreign material from falling into the hole after drilling. Verify that the drill holes are free of obstructions for their entire depth before placing charges. Take precautions to prevent material from entering the drill holes during loading operations. Stem all presplit holes a minimum of 3 feet (915 mm) with stemming meeting the requirements of this specification. The Contractor may pre-split the slope face before production drilling or pre-split the slope face and production blast at the same time if the pre-split drill holes are fired simultaneously at least 100 milliseconds before the production blast. Do not delay pre-split holes more than 25 milliseconds, hole to hole, to reduce noise and ground vibration. Prior to loading any blast holes, check and measure holes for conformance to the submitted blast plan. The Blasting Consultant is responsible for verifying the location and depth of these holes. If the blast holes are not drilled to the correct depth, are plugged, or are unable to be fully loaded, clean out or re-drill those holes not meeting the contract requirements or the submitted blast plan. The Blasting Consultant is responsible for verifying that all explosives and stemming are installed in accordance with the submitted blast plan. Notify the Project Manager of any variations or deviations from the submitted blast plan. Submit a detailed written report on the discrepancies observed and recommended remedial action as soon as possible.
204.03.8 Scaling
Scale slopes throughout the duration of the contract, and at such frequency as required, removing all loose rocks, overhangs, or other hazards. Scale during or upon completion of excavation in each lift. Do not allow drilling of the next lift until this work has been completed. Scaling must be performed to industry standards and contract requirements. Perform additional stabilization or scaling, required as a result of the blasting, at no additional cost to the Department. The Project Manager has the authority to prohibit or halt blasting operations if: • The required slopes are not being obtained in a stable condition. • The safety and convenience of the traveling public is being jeopardized; or • Unsatisfactory blast results are being obtained as defined in Subsection 204.03.4 . All costs incurred in adopting revised blasting methods necessary to produce acceptable blasting results are the sole responsibility of the Contractor.
204.03.9 Records
A.Drilling Logs. Daily, and prior to loading any explosives, provide copies of the daily drilling logs to the Blasting Consultant, the Blaster-in-Charge, and the Project Manager. Include all of the following information, at a minimum, for each hole drilled:
1.Drill hole location within the blast pattern (i.e., row number and hole number).
2.Drill hole diameter. 2020 EDITION V5.1 BLASTING – 204 204-9
3.Total depth of drill hole.
4.Drill hole angle.
5.Depth of overburden.
6.Depth to any changes in material hardness (e.g., clay seams, sand seams, soft rock, coal seams, etc.).
7.Depth and length of any voids encountered.
8.Depth to water if encountered.
9.Date drilled.
10.Driller’s name.
B.Blasting Logs. On a weekly basis, provide the daily logs of blasting operations. Include the numbers, times, dates, blasting locations, and patterns of all blasts in the logs for that week. Additionally, include all of the following information:
1.Any variations from the reviewed blasting plan.
2.Trade names and sizes of all explosives.
3.Explosives consumption and loss reports.
4.All ground vibration and air overpressure records.
5.Signature of Blaster-in-Charge.
204.03.10 Survey
A.Pre-Blast Condition Survey. Have the blast consultant arrange for a pre-blast survey of any nearby buildings, structures, utilities, or other appurtenances that may potentially be at risk from blasting damage. Use a survey method acceptable to the Contractor’s insurance company. Submit copies of all pre-blast survey records for review before blasting operations begin. Notify occupants/owners of local buildings, structures, utilities, or other appurtenances a minimum of 48 hours prior to the start of blasting operations.
B.Post-Blast Condition Survey. If complaints of damage or annoyance are made, have the blast consultant arrange for a post-blast survey of any nearby buildings, structures, utilities, or other appurtenances affected by blasting. Use a survey method acceptable to the Contractor’s insurance company. Be responsible for any damage as described in Subsections 107.15 and 204.03.2 . Submit all post-blast survey records for review within 48 hours of completing the survey. Notify the Project Manager of any damage or annoyance claims from occupants/owners of local buildings, structures, utilities, or other appurtenances a within 24 hours of the complaint.
C.Vibration Control and Monitoring. Have the blast consultant establish a vibration control and monitoring program. Submit the vibration control and monitoring program for review or at any time the drilling and blasting methods are changed. When blasting near buildings, structures, or utilities, or other appurtenances that may be subject to damage from blast induced ground vibrations; control the ground vibrations by using properly designed delay sequences and allowable charge weights per delay. Establish allowable charge weights per delay by carrying out test blasts and measuring vibration levels. Confirm that the test blasts, in accordance with Subsection 204.03.4 and modified as required, limit ground vibrations to below damage thresholds. Monitor each blast using an approved seismograph(s) located, in accordance with the submitted Master Blasting Plan, between the blast area and the closest structure(s) subject to blast damage whenever vibration damage to adjacent structures is possible. Use a seismograph(s) capable of recording peak particle velocity for three mutually perpendicular components of vibration in the ranges typical for blasting operations. All 204 – BLASTING 2020 EDITION V5.1 204-10 seismographs employed for monitoring are required to be calibrated within the preceding 12 months. Submit current calibration certifications. Do not allow peak particle velocity or frequency of each component to exceed the safe limits of the nearest structure subject to vibration damage. Have the Blasting Consultant interpret the seismograph records to ensure that the seismograph data is effectively utilized in the control of the blasting operations with respect to the existing structures. Provide the data recorded for each blast prior to the next blast and include the following:
1.Identification of instrument used.
2.Name of qualified 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/placed.
5.Maximum peak particle velocity and frequency in each component.
6.A dated and signed copy of photographic records of seismograph readings. Table 204-1 lists suggested conservative limits for maximum peak particle velocity and minimum frequency. TABLE 204-1 SEISMOGRAPH TOLERANCES Structure Type Maximum Peak Particle Velocity, inches per second Minimum Vibration Frequency, Hertz Green concrete (less than 7 days) 1.00 18 All other structures; utilities; wells; springs; and aquifers 2.00 30 The Blasting Consultant has the authority to modify the above parameters to safely meet contract and environmental requirements. Older deteriorated structures, utilities, or structures housing computers or other sensitive equipment may require lower peak particle velocity and different frequency limits than given in Table 204-1. Additionally, buried pipelines, fiber optic cables, or other appurtenances owned by private utility companies or structures owned by other entities may be subject to lower limiting values imposed by the owner. On critical projects where vibration and frequency control is important, have an experienced vibration specialist establish safe vibration limits. In special cases, the Blasting Consultant may use the Blasting Level Chart, (Figure 1, page 24, OSMRE Guidelines) to determine maximum allowable ground vibration. This figure provides alternative blasting level criteria based on blast vibration frequency and maximum allowable peak particle velocity. The Blasting Consultant is responsible for; all necessary materials and equipment utilized in the performance of this work, for providing a high-speed film or video record of each blast, to be available to perform evaluation, monitoring, and record keeping as described above and as directed by the Project Manager.
204.03.11 Noise and Debris Control
A.Air Overpressure and Noise Control. Have the Blasting Consultant install an air overpressure monitoring system, if appropriate, between the main blasting area and the nearest structure subject to blast damage or other detrimental effects. Ensure the 2020 EDITION V5.1 BLASTING – 204 204-11 equipment used to make the air overpressure measurements is the type specifically manufactured for that purpose. Hold peak overpressure below 0.05 psi (0.34 kPa) at the nearest structure or other designated location. Use appropriate blast hole patterns, stemming, and detonation systems to prevent venting of blasts and to minimize air overpressure and noise levels produced by the blasting operations. Lower the overpressure limit if it proves too high based on damage or complaints. Immediately after each blast, furnish a permanent signed and dated record of the peak overpressure measurements.
B.Fly Rock Control. Where necessary, use approved blasting mats, soil, or other equally serviceable materials or containment methods to prevent fly rock and/or debris. Permit violations, resulting from blasting operations, are the sole responsibility of the Contractor.
204.03.12 Controlled Blasting
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 back slope. Controlled blasting techniques include presplitting and cushion (trim) blasting. All final slopes identified in the contract as pre-split slopes must be excavated with controlled blasting methods. Ripping is not allowed within 10 feet (3 m) of the final slope face.
A.General. Meet all requirements of Subsection 204.03 , as well as the following:
1.When presplitting, detonate the presplit line before detonating any production holes.
2.Cushion blasting is similar to presplitting, except detonation along the cut face is after the detonation of the production holes.
3.Unless otherwise approved by the Project Manager, begin tests using controlled blast holes spaced 2½ feet (760 mm), adjusting, if necessary, to a maximum spacing of 3.0 feet (915 mm), until the Project Manager approves the spacing to be used for a full- scale controlled blasting operation.
B.Controlled Blasting Methods
1.Presplitting. Perform all presplitting, including the blasting test sections, in accordance with Subsection 204.03.4 .
2.Cushion (Trim) Blasting. Cushion blast, in lieu of presplitting, where the horizontal distance from the cut face to the existing rock face is less than 15 feet (5 m). The difference in delay time between the trim line and the nearest production row cannot be more than 75 milliseconds or less than 25 milliseconds.
204.04 Method of Measurement
204.04.1 Drill Pre-Splitting Holes
A.Production Blasting. Production blasting is incidental to and included in the measurement for Unclassified Excavation in accordance with Section 203 .
B.Controlled Blasting. Drill pre-splitting holes are measured by the linear foot (m) of controlled blast hole. The measurement is made from hole collar to a depth of 2 feet (610 mm) below finished ditch grade. Holes with alignments not meeting the requirements of Subsection 204.03.3 are not measured for payment. Quantities shown in the contract are based on 2½-foot (760 mm) hole spacing. Actual quantities will depend on field conditions and results from test sections. The quantity of drill pre-splitting holes shown in the contract is not guaranteed, and the Department reserves the right to increase or decrease this item with no adjustment in the contract unit price. 204 – BLASTING 2020 EDITION V5.1 204-12
204.04.2 Blasting Consultant
Blasting Consultant is measured by the lump sum.
204.05 Basis of Payment
Payment for the completed and accepted quantities is made under the following: Pay Item Pay Unit Blasting Consultant Lump Sum Drill Pre-Splitting Holes Linear Foot (m) Equipment to perform vibration and air overpressure monitoring, pre-blast and post-blast surveying, film, videotape, and other expendable materials are incidental to Blasting Consultant work and are not paid separately. Payment for all costs associated with Blasting Consultant work is included in the lump sum bid price for Blasting Consultant.
204.05.1 Production Blasting
Payment for all costs associated with production blasting including materials, explosives, labor, tools, and equipment is included in the contract unit price per cubic yard (m3) of Unclassified Excavation.
204.05.2 Controlled Blasting
Payment for all costs associated with controlled blasting including materials, explosives, labor, tools, and equipment is included in the contract unit price per linear foot (m) of drill pre- splitting holes.
Referenced in this section
Blasting in other states
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Source: Standard Specifications for Road and Bridge Construction, 2020 (v5.1) Edition. Pages 161–172 of 611. View official source ↗