J. David Rogers, Ph.D., P.E., R.G., C.E.G.
Karl F. Hasselmann Chair in Geological Engineering
Department of Geological Engineering
University of Missouri-Rolla
129 McNutt Hall, 1870 Miner Circle
Rolla, MO 65409-0230

ROCK EXCAVATION

A.  Rock excavation shall include removal and disposal of the following: (1) all boulders measuring 1/3 of a cubic yard or more in volume; (2) all rock material in ledges, bedding deposits, and un-stratified masses which cannot be removed without systematic drilling and blasting; (3) concrete or masonry structures which have been abandoned; and (4) conglomerate deposits which are so firmly cemented that they possess the characteristics of solid rock and which cannot be removed without systematic drilling and blasting. Except where trees are indicated to be removed, trees shall be protected from injury during construction operations.  No tree roots over 2 inches in diameter shall be cut without express permission of the ENGINEER.  Trees shall be supported during excavation by any means previously reviewed by the ENGINEER.

B.  It is expected that nearly all excavation can be accomplished using conventional equipment.

1.  For general excavation, a D-9N Caterpillar tractor with a single shank ripper, or equivalent equipment, is considered conventional equipment, if it can rip at a production rate of at least 300 bank cubic yards per hour.

2.  For trench excavation, a 235C Caterpillar excavator with a medium stick and a rock ripping bucket, or equivalent equipment, is considered conventional equipment, if it can excavate at a production rate of at least 30 bank cubic yards per hour.

C.  If material is encountered which the CONTRACTOR believes cannot be excavated by conventional equipment, the ENGINEER shall be immediately notified. The CONTRACTOR shall provide performance tests of the specified conventional or equivalent equipment.  If the ENGINEER confirms in writing that the specified conventional equipment cannot perform at the production rates specified, the excavation shall be considered rock excavation.

D.  In areas to be later rip-rapped, large rock found during excavation of the stream channel may, upon approval of the ENGINEER, be left in place, excavated around and incorporated into the final riprap.

E.  Should the CONTRACTOR encounter bedrock or excessive large boulders within the stream channel which will require extensive excavation to achieve final grade, the CONTRACTOR shall immediately notify the ENGINEER.  The ENGINEER shall review the hydraulic requirements of the stream in the affected area in a timely manner and advise the CONTRACTOR on acceptable alternate excavation.

F.  Payment for rock excavation shall be as provided in the bid form as a unit price item, where provided.  If a unit price item for rock excavation is not provided in the bid form, the extra cost for excavation of rock shall be treated as a change order.

G.  Explosives and Blasting

1.  General: It is not anticipated that blasting will be required for this project. Should the CONTRACTOR exhaust conventional equipment and methods for rock excavation and removal and desire to use explosives to accomplish this WORK, it shall comply with the following:

a.  Blasting and storage and handling of explosives shall be in accordance with the Construction Safety Orders of the Division of Industrial Safety of the California Department of Industrial Relations, Federal Safety Requirements, the San Mateo County Sheriff, and other authorities which have jurisdiction.

b.  The CONTRACTOR shall obtain all necessary permits and furnish copies to the Engineer before explosives are transported to the site.  The CONTRACTOR shall pay for permits at no additional cost to the OWNER.

c.  Blasting shall be done only by skilled operators under the direction of a licensed foreman.

d.  The CONTRACTOR shall identify all property, structures, and persons which may be affected by blasting and shall take all safety precautions and protective measures to prevent damage or injury to same.  All personal injury or damage to persons or property of any nature, whether in the WORK or appurtenant to it, shall be the responsibility of the CONTRACTOR.

e.  The CONTRACTOR agrees by submission of a bid to indemnify and hold the OWNER, its officers, agents, employees, and the ENGINEER harmless from any and all liability claims, costs, expenses including expenses of investigation and defending against same in regard thereto.

f.  Blasting shall only be permitted between 9:00 AM and 4:00 PM, Monday through Friday, unless otherwise approved by the ENGINEER and regulatory agencies having jurisdiction.  Blasting will not be permitted on legal holidays.

2. Pre-Blasting

a.  Inspections of all structures within [300-feet] of the blast site shall be made more than 2 weeks prior to commencement of blasting.  A qualified independent inspector shall perform the inspections for the purpose of detecting and documenting any visible or reasonable recognizable pre-existing defects or damages in structures.

b.  Waiver of inspections shall be in writing, signed by structure owners or persons with control or custody of the structures.

c.  Complete inspection reports listing findings with photographs or waivers shall be signed by the inspector.  One copy of inspection reports and waivers, shall be submitted to the ENGINEER before blasting commences.

d.  The CONTRACTOR shall give 30 and 5-day notices to all residence and businesses, and utility owners which may be affected by blasting.

3. Blasting

a.  The CONTRACTOR shall perform instrumented seismographic monitoring on blasting. A seismograph shall be placed at [the nearest structure to the blast] to monitor the ground motion particle velocity and frequency during each blast. One copy of each daily seismograph chart shall be furnished to ENGINEER.

b.  Fly rock from blasting shall be contained within the project site and shall not represent a hazard to persons, vehicles, existing improvements, or vegetation.

c.  The blasting site shall be cleaned of all debris at the end of each day.

d.  No blasting shall be done within 100-feet of concrete which has been placed in less than 7 days, except by permission of the ENGINEER.

4. Post-Blasting

a.  The independent inspector shall investigate each complaint of property damage and a written report shall be furnished to the ENGINEER within 30 days of receipt of the complaint.

 

Questions or comments on this page?
E-mail Dr. J David Rogers at rogersda@umr.edu.