51-Sec 31 23 16.26 Rock Removal.pdf
PDF 92 KB Posted
- Attached to
- 2201256.01 - Whistlestop Park
- Solicitation number
- US.160528
- Issued by
- Montgomery County, Pennsylvania
About this file
This is a technical specification document for rock removal work that may be applicable to the Whistlestop Park project being procured by Montgomery Township in Pennsylvania. The specification establishes requirements for the removal of identified and discovered rock during excavation using both mechanical and explosive methods. The work includes drilling, wedging, blasting, and mechanical surface impact equipment to disintegrate rock that cannot be removed with standard heavy equipment weighing at least 70,000 pounds. Key requirements include engaging a seismic monitoring firm and an explosives firm, each with a minimum of five years documented experience, with all blasting performed by or under supervision of an individual holding a valid Commonwealth of Pennsylvania blaster's license. The contractor must conduct pre-blasting surveys and document conditions of nearby buildings, structures, and wells within 500 feet of excavation areas, including structural photography and water quality sampling. No blasting shall occur within 50 feet of utility lines being constructed or within 100 feet of recently placed concrete (within 48 hours), and paving must be pre-cut before blasting to prevent heaving beyond normal trench width.
The specification requires strict compliance with Pennsylvania Department of Labor and Industry regulations for storage, handling, and use of explosives, as well as NFPA 495 standards. All explosives must be stored securely on-site in quantities only as needed and only during active use periods, with caps and detonators stored separately. Rock excavation within ten feet of underground utilities must be performed by hand or with light explosive charges at the Owner's discretion. Utility trenches must be excavated to 6 inches below the pipe invert elevation and 12 to 16 inches wider than the pipe outer diameter with a minimum 6-inch clearance on each side. The contractor must provide visual inspection by the Resident Project Representative of all trench bottoms, foundation bearing surfaces, and cavities prior to further construction, and must repair any damage from blasting operations including damaged paving beyond trench width.
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Text version
ROCK REMOVAL
31 23 16.26-1
SECTION 31 23 16.26
PART 1 GENERAL
1.01 SECTION DESCRIPTION:
A. The Work of This Section Includes:
1. Removal of identified and discovered rock during excavation.
2. Mechanical methods and explosive methods to assist rock removal.
1.02 RELATED INFORMATION
A. Related Work Specified Elsewhere:
1. Section 31 20 00: Earthwork
2. Section 31 23 33: Excavation, Backfill and Compaction
1.03 QUALITY ASSURANCE
A. Reference Standards:
1. National Fire Protection Association (NFPA): NFPA 495 - Code for Manufacture, Transportation, Storage, and Use of Explosive Materials
B. Seismic Monitoring Firm: Company specializing in seismic surveys with five (5) years documented experience.
C. Explosives Firm: Company specializing in explosives for disintegration of rock, with five (5) years documented experience. All blasting shall be performed by or under the supervision of an individual with a valid Commonwealth of Pennsylvania blaster's license.
1.04 DEFINITIONS
A. Rock: Solid mineral material of a size that cannot be removed with a "Trac-Hoe" style machine with a minimum weight of 70,000 pounds (without use of drilling and wedging, blasting, and/or mechanical surface impact equipment).
1.05 REGULATORY REQUIREMENTS
A. Conform to "Regulations for the Storage, Handling and Use of Explosives" of the Pennsylvania Department of Labor and Industry; and to NFPA 495 for handling explosive materials.
B. Obtain all required permits from various local and/or State agencies among which are those noted in Items B, C and D of Paragraph 1.26 of the Supplementary Conditions (Document 00 73 00).
C. Comply with all permit conditions including timely notifications to all required agencies/officials.
31 23 16.26-2
1.06 PROJECT CONDITIONS
A. Advise owners of adjacent buildings or structures in writing, prior to performing any blasting operations to explain planned blasting operations, and pre-blast survey.
B. Conduct a pre-blasting survey and document conditions of nearby buildings, structures and wells, prior to blasting, in order to assess, record and photograph existing structural conditions of buildings (interior & exterior) identifying existing irregularities and to monitor water supply wells for water level along with samples for total coliform organisms and turbidity. Nearby buildings, structures and wells are considered to be those within 500 feet of any trench or site excavation requiring rock removal. Monitoring and sample results from the water supply wells and structural observations of buildings shall be immediately forwarded to Owner and Engineer.
C. Store all explosives in a secure and safe manner in strict conformance to all State and local municipal regulations; storage locations shall be clearly marked "DANGEROUS EXPLOSIVES", and shall be in care of a competent watchman at all times. In no case shall caps or other detonators be stored or transported with explosives. Explosives shall be kept on the site only in such quantities as anticipated to be required for the Project and only during the time when being used.
D. Rock excavation within ten (10) feet of underground utilities or structures shall be done by hand or with light charges of explosives with exercise of utmost care to avoid disturbance.
Owner reserves the right to direct that rock be removed by methods other than blasting in such cases.
E. No blasting shall be performed within 50 feet of the utility lines being constructed as part of the Work nor for a period of at least 48 hours after concrete has been placed within 100 feet of the blasting operation.
F. Special care shall be exercised in areas where high tension power lines are located.
G. Paving shall be pre-cut before blasting within roads to prevent paving from heaving beyond normal trench width.
H. Areas to be pre-blasted to allow for future construction are noted on the Drawings.]
1.07 SCHEDULING
A. Schedule Work under the provisions of Section 01 33 00 concerning the submittal for a Construction Progress Schedule.
B. Schedule Work to avoid disruption to occupied buildings nearby.
PART 2 PRODUCTS
2.01 MATERIALS
A. Explosives: Type recommended by explosives firm.
B. Delay Device: Type recommended by explosives firm.
C. Blast Mat Materials: Type recommended by explosives firm.
D. Mechanical Disintegration Compound: Grout mix of materials that expand on curing.
31 23 16.26-3
PART 3 EXECUTION
3.01 EXAMINATION
A. Verify site conditions and note subsurface irregularities affecting work of this section.
3.02 PREPARATION
A. Identify required lines, levels, contours, and datum.
3.03 ROCK REMOVAL BY A MECHANICAL METHOD
A. Excavate and remove rock by the mechanical method.
B. Drill holes and utilize expansive tools, wedges, and/or mechanical disintegration compound to fracture rock.
C. Cut away rock at bottom of excavation to form level bearing.
D. Remove shaled layers to provide sound and unshattered base for footings and foundations.
E. In utility trenches, excavate to 6 inches below invert elevation of pipe and 12-16 inches wider than pipe outside diameter (minimum 6 inches on each side).
F. Shattered or fractured rock may be allowed by Owner as trench backfill where native backfill material is permitted provided that the size requirement in Section 31 23 33 (Item 2.03) is achieved. Otherwise, excavated rock must be removed from site.
G. Correct unrequired rock removal in accordance with the requirements of Section 31 23 33.
3.04 ROCK REMOVAL BY EXPLOSIVE METHODS
A. If rock is uncovered requiring the explosives method for rock disintegration, notify Engineer and execute as follows.
B. Provide seismographic monitoring during progress of blasting operations. Keep and submit to Owner upon request an accurate record of each blast which includes the general location of the blast, the depth and number of drill holes, the kind and quantity of explosive used, particle velocity and displacement, decibels, and other data as required for a complete record.
C. Drill blasting holes, prepare blasting charges and cover area with blasting mats.
D. Perform blasting to disintegrate rock and remove from excavation. Use such quantities and strengths of explosives and perform blasting in such manner as will break the rock approximately to the desired lines and grades, yet will leave rock not requiring excavation in an unshattered condition.
E. Remove rock at excavation bottom to form level bearing.
F. Remove shaled layers to provide a sound and unshattered base for footings, foundations, and utility construction.
G. In utility trenches, excavate to 6 inches below invert elevation of pipe and 12-16 inches wider
31 23 16.26-4 than pipe outer diameter (minimum 6 inches on each side).
H. Shattered or fractured rock may be allowed by Owner as trench backfill where native backfill material is permitted provided that the size requirement is in Section 31 23 33 (Item 2.03) is achieved. Otherwise, excavated rock must be removed from site.
I. Correct unrequired rock removal in accordance with the requirements of Section 31 23 33.
J. Repair any damage from blasting operations including damaged paving beyond trench width.
3.05 FIELD QUALITY CONTROL
A. Contractor shall provide for visual inspection by Resident Project Representative all trench bottoms, foundation bearing surfaces and cavities formed by removed rock prior to further construction.
END OF SECTION
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