SS-01024
(New)

THE STANDARD SPECIFICATIONS, SERIES 2001, ARE AMENDED BY THE FOLLOWING MODIFICATIONS AND ADDITIONS. THESE ARE SUPPLEMENTAL SPECIFICATIONS AND THEY SHALL PREVAIL OVER THOSE PUBLISHED IN THE STANDARD SPECIFICATIONS.

01024.01  DESCRIPTION.
These Specifications cover the work of pre-splitting a rock slope cut by establishing a free surface in the rock by the controlled usage of explosives placed in properly aligned and spaced drill holes.  The contract documents may specify more than one elevation level of pre-split holes.

These Specifications also cover the work of production blasting an area to be excavated by the controlled usage of explosives placed in properly aligned and spaced drill holes.

01024.02  MATERIALS.
All blasting material for production blasting shall be in accordance with the explosive manufacturer's instructions. 

01024.03  CONSTRUCTION.

A.  Removal of Material Above the Top Pre-Split Hole Line Elevation.
The Contractor shall remove all material above the top elevation of the first level of pre-split drill holes.  The Contractor shall remove this material in accordance with Section 2102 of the Standard Specifications.

B.  Pre-Splitting.
For each elevation level of pre-split holes, the Contractor shall align the pre-split holes so that a finish slope is cut within reasonably close conformity with the design slope specified in the contract documents.  The Contractor shall space a line of pre-split holes so that uniform shear occurs between holes with minimum disturbance of the rock cut face.  The maximum spacing between pre-split holes shall be 48 inches (1.2 m).

For each elevation level of pre-split holes, the Contractor shall drill each hole with a maximum length of 40 feet (10.5 m).  The Contractor shall drill each pre-split hole with a maximum diameter of 3.5 inches (90 mm).

All blasting procedures for pre-splitting shall be in accordance with the explosive manufacturer's instructions.  Before placing the explosive charge the Contractor shall determine that the hole is free of obstructions for the depth of the required cut.  In no case shall the maximum diameter of the explosives used be greater than one-half the diameter of the hole.

After explosive charges have been placed in the pre-split holes and prior to detonation, the Contractor shall backfill the holes with granular stemming material to contain the explosion.  The granular stemming material shall be as specified by the explosive manufacturer.  The Contractor shall take all measures to ensure that all voids that may be present in the pre-split holes are backfilled with stemming material.  If it is not possible to backfill a void with stemming material, the Contractor shall place the explosive charges in the hole so that detonation does not occur within the void area.

For each elevation level of pre-split holes, the Contractor may set or detonate explosive charges the full length of the pre-split line or sections of the pre-split line.  If detonation is by sections, detonation for each section of pre-split line shall extend at least 50 feet (15 m) past each production blast area or to the end of the pre-split line.  The Contractor shall detonate all explosive charges within the pre-split line or a section simultaneously.

C.   Production Blasting.
For each elevation level of pre-split holes, the Contractor shall place production blasting holes in a pattern so that material suitable for excavation will be produced adjacent to the pre-split hole lines.  The Contractor shall not place production holes within 8 feet (2.4 m) of the pre-split hole line, except when otherwise approved by the Engineer.  For each elevation level of pre-split holes, the Contractor shall not drill production blasting holes deeper than the minimum depth pre-split hole.

All blasting procedures for production blasting shall be in accordance with the explosive manufacturer's instructions.  After placing the explosive charges and prior to detonation, the Contractor shall backfill the production blasting holes with granular stemming material or another suitable method to contain the explosion as specified by the explosive manufacturer and as approved by the Engineer.

The Contractor shall detonate the explosive charges in a production blast area separately from the detonation of explosive charges of an adjacent pre-split line section.  The Contractor may use appropriate time delays when detonating the explosive charges of the production blast area and an adjacent pre-split line section if the pre-split line section is fired first and production blasting progresses so that the holes nearest the pre-split line are fired last.

After detonation, the Contractor shall excavate material in the production blast area as Class 12 Excavation in accordance with Section 2102 of the Standard Specifications.

01024.04  METHOD OF MEASUREMENT.
The Engineer will determine the square yards (square meters) of Pre-splitting of Rock Cuts for payment by calculating the area of the pre-split face.

The work of removing material above the top elevation of the first level of pre-split holes will be measured for the specified class of excavation in accordance with Article 2102.13, A, of the Standard Specifications.

The work of production blasting (including drilling holes, setting and detonating explosive charges, and removing material from the production blast area) will not be measured separately for payment, but will be measured as part of the Class 12 Excavation in accordance with Article 2102.13, A, of the Standard Specifications.

01024.05  BASIS OF PAYMENT.
The Contractor will be paid the contract unit price per square yard (square meter) for Pre-splitting of Rock Cuts as determined in accordance with Article 01024.04 of this Specification.  This payment shall include full compensation for all labor, equipment, and materials necessary to drill the pre-split holes, place explosive charges, and detonate explosive charges to produce a finished acceptable slope cut for each elevation level of pre-split holes.

The Contractor will be paid for the work of removing material above the top elevation of the first level of pre-split holes for the class of excavation specified in the contract documents in accordance with Article 2102.14, A, of the Standard Specifications.

The Contractor will be paid for the work of production blasting, including drilling holes, setting and detonating explosive charges, and removing material from the production blast area as part of Class 12 Excavation in accordance with Article 2102.14, Paragraph A, of the Standard Specifications.