207BLASTING FOR ROCK CUT SLOPE EXCAVATION

207.1DESCRIPTION—This work is excavation of rock using controlled blasting and production blasting

to achieve a uniform face in the rock along the plane of the specified excavation back slope.

spaced and aligned blastholes to produce a uniform surface in the rock along a specified excavation back slope. Controlled blasting methods include:

plane of the specified final excavation back slope. Presplitting uses reduced blasthole spacing, diameter, and explosive charges. The initiation of blasting in the presplit blastholes precedes the initiation of the adjacent production blasthole explosives by a delay. The delay decouples the final excavate d rock face from the excavation and prevents energy from production blasts from propagating to, and damaging, the final cut face.

and fractures in the finished rock face when there is an insufficient burden of 15 feet or less for production blasting. It is similar to presplit blasting, but without production blast holes.

controlled blastholes. Production blastholes are drilled in a pattern throughout the main excavation area adjacent to the controlled blast row. Production blastholes are detonated in a controlled delay sequence toward an open face or relief produced by blastholes firing on an earlier delay. Production blasting fragments the rock in the area to be excavated, to the size required for removal and placement.

207.2MATERIALS—

have not been exposed to weather. Non-electric detonators and initiating devices include, but are not limited to, all explosive materials, initiators, blasting caps, detonating cord, delays and timing devices, and all other materials and devices necessary to perform the work. While electric detonators are not allowed, electronic programmable detonators are permissible for use. Submit copies of the technical data sheets and safety data sheets for all materials to the Representative with the Blasting Plan. All blasting caps for any individual shot must come from one manufacturer.

207.3CONSTRUCTION—

methods cannot produce a uniform excavated surface at the specified slope angle. Conduct all blasting, explosive handling, and monitoring operations according to the latest OSHA standards, 29 CFR Parts 1926.900 through 1926.914 and Pennsylvania Code, Title 25 Environmental Resources, Article IV – Chapter 77, Chapter 210, Chapter 211, and all local requirements. Maintain a copy of all standards on site including health and safety requirements and make available upon request.

following qualifications: The blaster must submit to the Representative a list containing at least five successfully completed similar projects that, together, demonstrate a minimum of 3 years of experience in surface rock blasting including controlled blasting. Include a brief description of each project, and the name and telephone number of the owner’s representative knowledgeable in each project listed. The Department will review and approve the blaster. Receipt of written approval must be obtained before any blasting operations including drilling of blastholes are initiated. Allow at least 21 calendar days for approval.

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cut slope exceeding a vertical height of 10 feet and a slope equal to or steeper than 0.5(H):1(V). The Department may require controlled blasting to form the faces of more gradual slopes or excavations, even if the slopes could be formed by non-blasting methods. Conduct presplit test sections to determine the presplit blast pattern and design necessary to achieve the required results. The conditions of each presplit section will be evaluated by the Representative. Revisions to the presplit blast design must be made by the blaster, as necessary, to achieve the required results before drilling can proceed in adjacent presplit sections.

fragmented, in-situ rock that can be removed, processed , and/or placed as required. Locate and drill t he production blasthole as specified in Section 207.3(g). Prepare the production Blasting Plan so as not to affect the controlled blastholes. Where blasting is adjacent to highways with lane closure restrictions, the volume of rock cannot exceed the Contractor’s ability to remove t he blasted material from the highway within the established maximum allowable closure time.

The sequence of blasting at any blast is as follows:

• Conduct and submit the Pre-Blast Survey.

• Submit and obtain acceptance of the Blasting Plan.

• Submit and obtain acceptance of the Blasting Safety Plan.

• Before blasting operations, conduct and submit the Water Supply Monitoring Report.

• Notify appropriate entities of blasting schedule (property owners, utilities, traffic, flagging, and police).

• Schedule and conduct the Pre-Blast meeting.

• Obtain Department approval and selection of the test section.

• Drill and conduct test section blasting before the start of any full-scale blasting operations.

• Proceed with full-scale drilling and blasting.

• Submit required Blasting Report including Vibration and Airblast Monitoring Reports.

• Remove rock and scale if required.

• Inspect and evaluate rock face/excavation results (including any required modifications).

• If applicable, submit a modified Blasting Plan for adjacent blasts in that project work area.

• Conduct and submit the Post-Blast Survey.

• Post blasting operations, conduct and submit the Water Supply Monitoring Report.

utilities within 300 feet of the blasting site, and within 1,000 feet of the blasting site if the blast is designed for a peak particle velocity (PPV) exceeding 0.5 inches per second (confirm by vibration monitoring). If no structure or building is located within these limits, complete one survey, at a minimum, on the closest structure or building within 1 mile of the blasting operations. Begin the Pre-Blast Survey no sooner than 6 weeks before the beginning of blasting operations . Submit the completed Pre -Blast Survey at least 1 week before the Pre-Blast meeting. Complete the Exterior and Interior Pre -Blast Survey using Form TR -42. Alternative forms/reports are acceptable for use if they contain the information required on Form TR-42. Include structural observations

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and descriptions, locating any existing cracks, including length and size. Where significant cracks, structural defects, or damage exists, collect digital images to supplement the written description. Provide a scale and a date stamp on each digital image taken. Capture digital images at a minimum 8-megapixel resolution and submit electronically with the Pre-Blast Survey. Request, in writing, property access from each property owner where a Pre-Blast Survey is necessary. If the property owner does not allow access to the property for the Pre -Blast Survey, notify the Representative. If the property owner declines the Pre -Blast Survey, submit a notification letter and Form TR-43 that is signed by the property owner to the Representative. If the property owner refuses to sign, the qualified independent blasting consultant must indicate this and sign the waiver. Keep a copy of the letter and waiver on file as part of the Pre-Blast Survey Records. Do not enter any private property without written permission. The Pre-Blast Survey must be conducted by a qualified independent blasting consultant in the presence of the property owner. At the end of the Pre-Blast Survey, ensure the property owner signs both Exterior and Interior Pre-Blast Survey Forms and provide them a copy. Submit the Exterior and Interior Pre-Blast Survey Forms, including diagrams and digital images, at least 1 week before the Pre-Blast meeting. Notify the respective utility company within a minimum of 7 days before blasting of any utility within 300 feet of the blasting site and within 1,000 feet of the blasting site if the blast is designed for a PPV exceeding 0.5 inches per second. Provide notice in writing at 2 weeks and again 48 hours before blasting begins to all property owners where a Pre-Blast Survey was performed. Inform the residents that blasting signals will be issued according to Title 25 Pa. Code § 211.155 to warn of imminent blasting.

Meeting and before the start of drilling for blasting for each proposed rock cut excavation that requires blasting, and at any time the drilling and blasting operations change. The Blasting Plan will be reviewed by the Department and any concerns will be discussed with the Contractor before acceptance of the Blasting Plan. Do not drill any blast holes until the Blasting Plan is accepted by the Department. Schedule and attend a pre -blast meeting at least 1 week before any explosives being brought onto the project site to review the following: the Blasting Safety Plan including requirements concerning explosives being brought onto the project site, the restrictions and requirements during the loading of explosives; the sequence of operations before, during, and after each blast; all required traffic control; all inspection procedures of blast zones for misfires, stability, blast material debris clean up; and any other relevant issues. At a minimum, the following must attend the pre -blast meeting: The Representative, the blaster, the Contractor, the qualified independent blasting consultant(s), and other personnel designated necessary by the Representative. Review and acceptance of any Blasting Plan by the Department does not rel ieve the Contractor of full responsibility for the accuracy of the plans, safety of operations, quality of work, or conformance to specification performance requirements, when implemented in the field. Complete the Blasting Plan using Form TR -40 and include in the submittal of the Blasting Plan along with any necessary documentation. Alternative forms/reports are acceptable for use if they contain the information required on Form TR -40. Submit information and documentation with the Blasting Plan that includes, but is not limited to, the following:

• A completed Blasting Activity Permit approved by the DEP Bureau of Mining and Reclamation. Include any other necessary permits required to complete blasting activities according to current applicable federal, state, and local requirements.

• Station limits of the proposed shots, critical distances and directions to structures, buildings, or utilities, and pre-blast survey limits detailed on the plan view sheets. Also, include scaled distance and estimated PPV.

• One plan and section view for each rock cut excavation showing the proposed drill pattern for any blastholes, including blasthole spacing, blasthole diameters, blasthole angles, lift height, drill depth, buffer rows, and burden. Accurately show to scale each cut area to be blasted.

• Loading diagram(s) detailing the type, amount, and specific gravity of explosives, primers, and initiators. Also include the location and depth of stemming.

• Initiation sequence(s) of any blastholes including delay times and delay system(s)

• Schedule and timeframes for notification of the blasting sequence.

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• Manufacturer’s product data sheets for all explosives, primers, and initiators to be used in the work.

• A Maintenance and Protection of Traffic Plan which details how traffic will be protected and managed during blasting.

• Methods to control site security, vibration, flyrock, and airblast levels.

• Method and quality control of the depth, direction, and alignment of the drilled blastholes for blasting.

• Licensing information, experience, and qualifications of the blaster who will be directly responsible for the loading and firing of each shot.

• The name and qualifications of the licensed blaster in the State of Pennsylvania responsible for designing and directing the blasting operation.

• The qualified independent blasting consultant(s) proposed to conduct and complete the Pre - and Post- Blast Surveys, and the Airblast, Vibration, and Water Supply Monitoring Reports.

and delivery locations, blasting procedures, and the use of explosives at the project work area at least 3 weeks before the start of drilling for blasting. The Blasting Safety Plan must include, but is not limited to, the following:

• Details about hazard communication programs for employees.

• Equipment that will be used to monitor the approach of lightning storms, and evacuation and site security plans in the event of a storm.

• Methods for preventing spills or losses of explosives, drilling fluids, oil, or any other pollutants into the ground during all handling and blasthole loading operations. Include details of all containment and contingency plans for quickly and effectively cleaning up any spilled materials.

• A safe and approved disposal method of all explosive packaging materials.

• Detailed contingency plan(s) for handling misfires of explosives resulting from cutoffs or other causes.

• Fire prevention plan details, including smoking policies, procedures and limitations for work involving any open flames or sparks, and description and location of all firefighting equipment and evacuation plans.

• One hard or electronic copy of the blaster’s valid Pennsylvania blasting license and the Contractor’s ATF blasting license.

• Other required county or state permits required for explosive use and storage.

• An explanation of how the explosive transport vehicles will meet all applicable ATF, OSHA, federal, state, county, and local regulations.

• If applicable and/or when underground mining is identified during design, provide air quality monitoring plans for local buildings.

Post and maintain in a visible area all current licenses required for blasting and explosive handling. Provide a certificate of insurance to the Representative showing that the Contractor retained the required insurance to the applicable limits to meet all local, state, and federal regulations. Store explosives on and off the project site according to OSHA standard, 29 CFR Part 1926.904, Title 27 CFR 181, Part 55, Subpart K, and in compliance with local requirements. The explosive transporters’ valid commercial driver’s

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license(s) with HazMat endorsements must be available and provided upon request. Maintain enough magazine records for stored explosives. Do not store bulk blasting agents such as Ammonium Nitrate and Fuel Oil (ANFO) on-site. Remain on-site once the blastholes are loaded with explosives until any misfires are resolved or remediated and the blast is completed. Do not leave explosives, blasting agents, detonators, or loaded blastholes unguarded or unattended at any time.

• Remove all overburden soil and loose rock along the top of the proposed cut and lay back to a stable condition before drilling and blasting.

• Drill blastholes one pattern at a time. When conditions justify simultaneous drilling and loading of blastholes, separate the two operations as widely as practical and not less than 50 feet apart.

• Check, measure, and record the depth of all blastholes when the drill is retracted from the blasthole. If any blasthole is found not to be open to the drilled depth, re-drill the short blastholes to the proper depth at no additional cost. If any blastholes are too deep, fill with stemming as specified in Section 207.2(a)1.

• Do not allow horizontal blastholes.

• Complete and submit with the Blasting Report, the Blasthole Drill Log, using Form TR -39. Alternative forms/reports are acceptable for use if they contain the information as required on Form TR-39. Keep accurate drilling logs on each blasthole to show the depth of the geological features such as zones of soft or weathered rock, mud or clay seams, voids, and color of drill cuttings. Also include the drilling rate (drill footage per work shift).

• If necessary, revise the Blasting Plan to address concerns during drilling. Obtain Department acceptance of the revised Blasting Plan before proceeding.

• Before loading of blastholes, post warning signs at points of access to the blasting site.

• Cover and design b lastholes to keep material from falling into the blastholes after drilling. Place reusable plastic hole markers in each blasthole to identify all blasthole locations.

• Measure blastholes before loading any explosives into the blastholes to ensure each blasthole is open to the original drilled depth and free of obstructions before placing a charge. Use precaution to prohibit caving of material from borehole sidewalls during placement of the charges.

• While loading the explosives into the drilled blastholes, allow only the blaster and those persons necessary for the loading process within 50 feet of a blast area.

• Stem all unloaded portions of the blastholes between 0.7 and 1.3 times the burden distance. The actual ratio may need to be refined after the initial blast ( i.e., test blast section or production blast). Stemming material must be as specified in Section 207.2(a)1.

• Employ appropriate explosives and accessories for the various conditions to achieve the specified cut slope design.

• If blasting is allowed on structure foundations, repair any over break beyond the desired Bottom of Footing Elevation (BOFE) by excavating broken materials and leveling off to the BOFE with Class C concrete, or as required.

• Furnish and use approved blasting mats when necessary to hold and suppress flyrock and prevent subsequent damage to property and roadway.

• Repair roadway, structures, utilities, and any property damage as a result of blasting at no additional cost.

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• The Contractor is liable for all injuries or deaths of persons and/or farm/domestic animals, and any damage to property caused by blasting.

specified in Section 207.3(e), and with the following:

• Conduct initial test blast section as one presplit blast pattern using variable spacing of 18 inches over 18 feet, 24 inches over 24 feet, 30 inches over 30 feet, and 36 inches over 36 feet using a maximum lift of 30 feet.

• Maintain hole to hole spacing requirements for 18 -inch and 24 -inch presplit patterns within 75 to 125 percent of the intended spacing. For 30-inch and 36-inch presplit patterns, hole to hole spacing must be within 6 inches of the intended spacing. Maintain h ole to hole spacing throughout presplitting. If the deviation of presplit blastholes exceeds the allowable tolerance, provide the Representative alternative drilling methods in a revised Blasting Plan to reduce deviation within the above specified tolerances. Obtain Department acceptance of the revised Blasting Plan before proceeding. Do not exceed 110 feet for test sections.

• Ensure the test section demonstrates the suitability of the proposed blast plan relative to fragmentation requirements, over break control, flyrock control, adequacy of stemming, and other appropriate or necessary factors.

• When results of the drill logs are unusual (i.e., encountering zones of soft or weathered rock, mud or clay pockets, voids; rate of penetration; and the color and character of drill cuttings), revise the Blasting Plan as necessary and obtain Department acceptance of the revised Blasting Plan before proceeding.

• When rock of different characteristics is encountered, perform a blasting test section.

• Excavate the blasted test section to fully expose the presplit face and provide the means to access the face so that the Representative can examine and evaluate the results of the blasted test sections. The Representative will examine the completed test section and select the blasthole spacing that demonstrates the best presplit face quality. If no acceptable conditions are found by the Representative upon examination of the test section, revise and submit to the Representative a new Blasting Plan for review and acceptance. Suspend drilling and blasting until the Blasting Plan is accepted. At no additional cost, conduct additional test sections at the same blasthole diameter and spacing used for the previous test section and adjust the explosive load until desired/acceptable results are obtained without exceeding the established PPV as specified in Section 207.3(j). Unsatisfactory results include, but are not limited to, excessive fragmentation beyond the indicated lines and grade, excessive flyrock, and poor timing delays. Upon completion of test blasting, obtain written approval from the Department to proceed with full scale blasting operations.

• Consulting the Representative may be justified to consider review of the findings and make an informed decision regarding an acceptable borehole deviation if repeated test blasts are conducted using different drilling techniques, the height of the lift in an attempt to meet the borehole deviation limits has been reduced, evidence is provided that the magnitude and direction of deviation between each blasthole has remained constant, and if it is determined that because of geologic conditions deviation tolerances are not achievable.

• The Department’s approval of the test blasting program and the techniques and procedures associated with test blasting does not relieve the Contractor of any responsibilities to employ appropriate safety measures and exercise proper supervision of blasting operations.

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207.3(e), and as follows:

• Employ a surveyor licensed in the Commonwealth of Pennsylvania to locate and mark each presplit blasthole shown on the Blasting Plan to produce an excavated slope to the lines and grade as indicated. Drill presplit blastholes within 3 inches of the staked location. Blastholes drilled beyond this limit will be rejected.

• Control the angle and bearing at which the drill steel enters the rock with an electro -mechanical or electronic device (smart level meeting accuracy conditions of plus or minus 0.2 degree) by attaching to or resting on the drilling equipment. Blasthole drilling will not be allowed if this device is missing or inoperative.

• Complete a borehole deviation survey of each presplit blasthole before loading the blastholes using an electronic, borehole deviation measuring system with a probe resolution of 0.2-degree accuracy. Provide a report of each blasthole deviation survey to the Representative including blasthole alignment and graphical output data. Also, the report must show that the alignment will produce the excavated face as indicated. Terrestrial Surveying may be employed as necessary to produce this report. The output software must be capable of plotting vertical profiles parallel and perpendicular to the slope. No blasthole must deviate by more than 6 inches parallel and perpendicular from the planned slope. Maintain hole to hole spacing throughout presplitting as specified in Section 207.3(f)1.

• Drill a replacement presplit blasthole if the blasthole is 12 or more inches from the intended spacing at no additional cost. Abandon presplit blastholes not meeting the accuracy requirements using stemming as specified in Section 207.2(a)1 at no additional cost.

• Drill presplit blastholes between 2.5 and 3 inches in diameter. If drilling accuracy requirements cannot be achieved during test blast sections, blastholes with a diameter not exceeding 4 inches may be drilled.

• Do not exceed a length of 30 feet in blastholes for any lift. The Department maintains the right to decrease the length of the presplit blastholes at any time because of poor performance.

• Drill presplit blastholes a minimum of 30 feet longitudinally beyond the limits of the production blastholes to be detonated or to the end of the cut.

• If the cut height requires more than one lift, offset a maximum of 24 inches between lifts for drill equipment clearance. Begin the presplit blasthole drilling at a point that allows for the necessary offsets and adjust to compensate for any drift that may occur in the upper lifts.

• Use only explosives manufactured specifically for presplitting in presplit blastholes. Bulk ANFO is prohibited in presplit blastholes. The maximum diameter of the explosives must not exceed one half the diameter of the presplit blasthole.

• Detonation of explosives in each blasthole in a presplit shot may be simultaneous or delayed because of noise or vibration concerns provided the hole-to-hole delay does not exceed 25 milliseconds.

• Initiate the blasting in the presplit blastholes before initiating the production blasthole explosives by a minimum of 25 milliseconds.

less than 15 feet, the Contractor may use trim blasting. Perform trim blasting as specified in Section 207.3(f)1 and 2, except there are no production blastholes.

• Do not exceed 6.25 inches in diameter for the production blastholes.

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• Drill the production blastholes in the patterns and to the depths established in the Blasting Plan. Do not drill blastholes to a depth that exceeds 30 feet.

• Drill the row of production blastholes adjacent to presplit blastholes. Drill the row of production blastholes on a plane parallel to the presplit blastholes. The distance between production blastholes and presplit blastholes will be based on a distance of 1 foot per inch in diameter of production blasthole.

• Drill the bottom of the production blastholes at an equal depth/elevation to the bottom of the controlled blastholes, except for the bottom lift for sub drilling.

• Do not blast within 5 feet above of an at-grade separation to minimize disturbance. Remove remaining rock above the top of the at grade separation by mechanical methods.

• Drill a line of buffer holes on a parallel plane adjacent to the presplit blastholes. Buffer hole spacing can range from one half the production blasthole spacing to two times the presplit blasthole spacing. Drill buffer holes between 2.5 and 3 inches in d iameter, and 3 feet from the presplit line. Do not load the buffer holes with more than 50 percent of the full explosive load that could be placed in a 3 -inch production blasthole.

• Maintain a burden distance that is not more than one half the bench height to control blasting effects. Determine the required burden distance so as not to over or under confine the blast and to prevent flyrock and backbreak of the presplit face.

• Drill the production blastholes within two blasthole diameters from the staked drill collar location. Survey the elevation at the collar of each drilled production blasthole to foundation grade and verify the production blastholes are not sub -drilled below final foundation grade. Blastholes drilled outside either tolerance must be backfilled with stemming and re -drilled at the proper location and grade as directed by the Representative and at no additional cost.

• Detonate production blastholes on a delay sequence toward the free face as specified in the Blasting Plan. Delay the detonation sequence from hole to hole within a row by a minimum of 2 milliseconds per foot of hole spacing. A delay of less than 2 milliseconds is acceptable if vibration, pre-spilt performance, and flyrock can be controlled. Delay the detonation sequence from row to row by a minimum of 2.5 times the hole-to-hole delay.

• Take all necessary precautions to minimize blast damage to the rock backslope during production blasting.

• Remove or stabilize rock along the cut face that is loose, hanging, or creates a potentially dangerous condition during or on completion of the excavation in each lift. Do not drill the next lift until this work is performed.

after making any blast and obtain acceptance before drilling of the next blast section is initiated. Alternative forms/reports are acceptable for use if they contain the information required on Form TR-41. Only the blaster who was reviewed and approved by the Department may perform blasting operations including the drilling of blastholes. At a minimum, the Blasting Report must include the following:

• Drill logs, drilling remarks, and loading and timing delays used in each blasthole of the blast.

• All blast monitoring documentation, which includes vibration and airblast monitoring data.

• Contractor’s evaluation of the blast performance.

• Two High-definition (minimum 1080p resolution and 60p frame rate) digital video recordings submitted in MPEG-4 file format (or acceptable variant as determined by the Representative) on a CD, DVD, or flash

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drive of any test, controlled, and/or production blasting. The two videos must be recorded at opposite angles of the blast and, if feasible, from an elevated angle and a ground angle.

• All damage incurred and details of complaints or comments.

• Blast area description, weather, Contractor/crew, and layout and timing diagram.

with the Department for any portion(s) of roadway that must have temporary closures or lane restrictions during blasts. The MPT Plan for any partial or full roadway closures and detours must be approved by the District Traffic Engineer (DTE). At a minimum, all traffic must be stopped during blasting operations on roadways where the Contractor or the Representative has determined that road users may be impacted by blasting operations. Traffic may be halted for periods not to exceed 15 minutes, or unless otherwise approved. Traffic may not resume after a blast until the area is clear of any debris, the excavated slope face is free of any loose material, and the blasted material is stockpiled into a stable mass until it can be removed from the site. Place enough of a barrier to temporarily separate blasted material between active roadway lanes and blasted material. Time between traffic stoppages will be determined by the Department. Blasting operations will not be allowed during peak traffic hours as determined by the Department’s DTE. Roadway closures are allowed Monday through Friday, 9:00 A.M. to 3:00 P .M. or as determined acceptable by the DTE. No blasting is allowed during holiday periods or local events as determined by the Department’s DTE. Notify the Department RTMC and State/local Police two times before each blasting event. The initial notification must be made 24 hours in advance of the expected blast time. A second notification must be made 15 minutes before stopping traffic for the blas t work. Provide enough flaggers to control traffic on all impacted roadways. When traffic is stopped for blasting, monitor the traffic queue. Provide a shadow vehicle on each affected approach, one in each direction, at least 300 feet in advance of the las t vehicle in the traffic queue. This vehicle must remain at least 300 feet in advance of the last vehicle as the length of the queue increases. It may be necessary to provide two of these vehicles with drivers working as a team if enough shoulder or roadside is not available for a single vehicle to safely drive in reverse along the roadway. Furnish, erect, and maintain on all affected roadways, appropriate standard signing according to the MUTCD, Part 6 Figure 6H -1 Blasting Zone (TA -2). These signs are in addition to any temporary traffic control devices as indicated or according to Publication 213. Provide patrol vehicles, one in each direction, to drive through the blast area, to determine the site has been completely cleared before the blast is detonated. Employ suitable precautionary measures and devices to prevent roadway damage (including pavement, drainage features, signing, traffic barrier and/or guide rail, lighting, traffic control devices, and any other roadway element). Precautionary measures and devices may include barriers, blasting mats, and other protective and control measures and devices. As soon as the blasting has been completed, inspect the work area for any unsafe conditions. An inspection of the roadway by one patrol vehicle in each direction must be completed before traffic is released. Provide excavation equipment on standby to clear any rock debris from the roadway immediately following inspection.

Use a minimum of five portable seismographs for each blast according to the International Society of Explosives Engineers Performance Specifications for Blasting Seismographs. Use seismographs capable of measuring particle velocities for three perpendicular components of vibration within a frequency response range from 2 to 250 Hz. Use seismographs that have received a factory calibration within the 12-month period preceding the blast recorded and according to the following:

• Complete the Vibration Monitoring Report using Form TR-44. Alternative forms/reports are acceptable for use if they contain the required information required on Form TR-44.

• Place four of the seismographs north, south, east, and west of the blast at the approved locations. Place the remaining seismograph at the nearest critical structure subject to blast induced damage.

• Monitor and record PPV and frequency for each blast.

• Provide the data recorded for each shot to the Representative before the next blast.

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• Do not blast within 10 feet of the closest structure.

• Do not blast within 250 feet of less than 3-day old concrete.

• Do not blast within 30 feet of newly placed concrete until it has reached 28 -day strength unless approved by the Department. For blasting greater than 30 feet away from new concrete, the ground vibration limits apply according to Table A.

Table A Age of Concrete Maximum PPV Less than 3 days No blasting After 3 days 1.0 in/sec After 28 days 2.0 in/sec

• Before test blasting, calculate the value of maximum powder charge per delay permissible using an initial conservative scaled distance of 50 for the distance between the critical structure and shot. The scaled distance is calculated by dividing the true distance (feet) from the blast to a point of concern by the square root of the maximum charge weight in pounds per delay.

• Plot the PPV measured from each seismograph versus the scaled distance between the blast and seismograph location on a logarithmic -logarithmic graph. From this plot determine the site -specific working scaled distance factor for a maximum particle velocity of 1.6 inches per second.

• The Representative and the qualified independent blasting consultant will confirm that the PPV of each component does not exceed the safe limits of the nearest structure subject to vibration damage. The limits for any of the three mutually perpendicular co mponents of PPV must be determined using Figure 1 of Title 25 Pa. Code § 211.151.

• For all subsequent blasts, the qualified independent blasting consultant will evaluate the resulting PPV measured by the seismographs by plotting the recorded PPV versus the scaled distance on a logarithmic- logarithmic graph and submit it for approval. If at any time a maximum particle velocity of 2.0 inches per second is exceeded a modification to the initially established working scaled distance is required.

• Stop all blasting operations if the vibration limits are exceeded until the Contractor reports to the Representative that no damage has occurred to structures covered in the Pre -Blast Survey and that corrective measures are in place to lower vibrations to required limits to minimize the potential for any damage from future blasting.

to blast damage or annoyance. Monitor airblast at a second location as determined by the Representative and according to the following requirements:

• Use airblast monitoring equipment of the type specifically manufactured for airblast measurements.

• Maintain a peak overpressure below 128 dB (0.007 pounds per square inch) for residential structures. Provide a dated record of the peak overpressure measurements to the Representative immediately after each shot or use the same reporting procedures and time intervals designated for vibration monitoring.

• Stop blasting operations if the established overpressure limits are exceeded until the airblast monitoring specialist reports to the Representative that no damage has occurred or will occur, and that corrective action has been taken to lower the peak airblast.

Representative before and after blasting operations, and when issues arise during blasting operations. The water supplies must include all wells, springs, or other ground water supplies used for human consumption.

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Retain a qualified independent blasting consultant to oversee and complete the water supply monitoring program. Complete the Water Supply Monitoring Report using Form TR -45. Alternative forms/reports are acceptable for use if they contain the required information on Form TR -45. The following information is required for the completion of the water supply monitoring program:

• Determine the quantity and quality of water by identifying and monitoring water supplies within 1,000 feet of the blasting location(s). If geologic conditions warrant, water supplies beyond 1,000 feet may be included if there are concerns for potential impact, or if deemed appropriate for risk management.

• Two weeks before the start of blasting operations and between 6 and 8 weeks after blasting operations conclude, where allowed by the owners, for all water supplies identified, measure and record water levels, well depths, existing flow rates, well yield, and any other pertinent information.

• Two weeks before the start of blasting operations and between 6 and 8 weeks after blasting operations conclude, complete field and laboratory analyses for the following field water quality data parameters (and any other requested parameters) from all identified water supplies: pH, Temperature, Specific Conductance, Turbidity, Total Coliforms, Fecal Coliforms/E. Coli, Nitrate, Nitrite, Chloride, Hardness, Iron, and Sulfates.

• Collect water samples using sample collection and preservation techniques specified by the testing laboratory.

• Complete water analyses by a DEP certified laboratory.

Within 10 weeks after completion of blasting operations provide the Representative a final report of the conclusions and results of the water supply monitoring program and, if applicable, indicate any impacts to local water supplies from blasting activities. The Department will investigate indicated impacts to determine the cause of a water supply loss.

of all blasting and rock excavation of all utilities, buildings, or structures for which a Pre -Blast Survey was performed unless a waiver was/is obtained from the property owner. Complete the Exterior and Interior Post- Blast Survey using Form TR-42. Alternative forms/reports are acceptable for use if they contain the required information on Form TR-42. Follow the procedures as specified in Section 207.3(b), to obtain arrangements for property access and submittal procedures to the Representative. The Post-Blast Survey must be completed by a qualified independent blasting consultant in the presence of the property owner. At the end of the Post-Blast Survey, the property owner must sign both Exterior and Interior Post-Blast Survey Forms and be provided a copy. Submit the duly witnessed and signed Exterior and Interior Post-Blast Survey Forms to the Representative. Include in the report any diagrams and 8-megapixel resolution minimum digital images of structures indicating size and location of cracks, separations or damage in foundations, walls, ceilings, floors, or other structural components. Also, include documentation of any reported damage to water supplies including wells and springs and any differences from the Exterior and Interior Pre-Blast Survey Forms. The Department will in no way relieve the Contractor of the responsibility for damage resulting from vibration or noise above the established allowable limits, and any other damages, including damages from flyrock, inadequate control or retention of blasted materials, improper or poor blast area security, or other damages resulting from improper or careless blasting practices or construction techniques.

207.4MEASUREMENT AND PAYMENT—Blasting for Rock Cut Slope Excavation is incidental to excavation

or borrow excavation. All material, explosives, labor, tools, and equipment needed for blasting operations including monitoring and survey activities will be considered incidental to the class of excavation specified and will not be paid for separately except as specified in Section 207.4(a).

Measured on linear foot of acceptable presplit or trim blasthole depth for blastholes drilled within the tolerance as specified in Section 207.3(f).