Occ. Code 7251300

 

CORE DRILL OPERATOR, GRADE 8

 

New York State Department of Civil Service

 

Classification Standard

 

These employees utilize equipment specifically designed to obtain samples of soil, rock, cores of Portland cement concrete pavement, structural Portland cement concrete and asphaltic concrete pavements for engineering testing and evaluation.

 

Core drilling equipment is operated to take sample cores of concrete and bituminous pavements at locations designated by engineering personnel. These cores are laboratory tested prior to final approval of contract work. In general, the crews travel between construction projects and operate the equipment on high­ways being used by the traveling public. The core is cut with a thin walled diamond bit, rotated by the engine of the core drill unit. The bit is fed vertical­ly by the hydraulically actuated, manually controlled mechanism of the core drill unit; the bit is cooled and the cuttings flushed by water circulated through a positive action rotary pump which is powered by the core drill unit engine.

 

Drill rig crews obtain subsurface information including soil and rock samples in advance of, or concurrent with, the design of engineering projects so that engineering personnel can determine the character and foundation strength of the earth for foundation and earth engineering purposes. The drill rig crews are responsible for progressing subsurface explorations using equipment specifically designed and manufactured to recover samples of soil and rock from borings progressed below the ground surface. The equipment utilized is capable of obtaining soil and rock samples to depths of over two hundred feet. Basically, the soil sampling operations consist of the following steps:

 

1.               Install drive pipe five feet into the ground using a 300 lb. weight, free falling 18 inches, using the cathead on the drill rig. Record the number of blows required to drive the pipe each foot.

 

2.               Clean out the pipe, using chopping bits and water under pumped pressure.

 

3.               Drive the soil sampler into the undisturbed soil below the bottom of the casing using a 300 lb. weight, free falling 18 inches. Record the number of blows required to drive the soil sampler each 6-inch increment.

 

4.               Withdraw the sampler and carefully remove the soil sample. Visually identify the soil material with respect to its color, moisture condition and components, i.e., sand, silt, clay, gravel, etc.

 

5.               Place the sample in a jar that is properly labeled to identify the project, station and offset, and the boring number, the sample number and the depth of the sample.

 

6.               Repeat 1 through 5 until the required depth of the boring is reached.

 

7.               If ledge rock or boulders are encountered, the soil sampling tools are re­placed by rock coring tools which may consist of single or double tube core barrels equipped with diamond bits. These core barrels are rotated by the drill rig. The operator must determine the optimum speed of rotation, the correct hydraulic pressure, the optimum rate of advance, and the correct water pressure to yield a true representation of the rock formation to achieve efficient production without damaging the diamonds set in the matrix of the bit.

 

8.               Data obtained in the borings is recorded in the field and includes the following: elevation of the boring; job identification; boring number; drilling method; sample elevations; limits of strata; groundwater data; detailed description of each soil and rock layer encountered; and penetra­tion resistance and rate of recovery.

 

All positions in this series maintain and make operating repairs to assigned equipment, except those repairs that require the services of a journey level mechanic.

 

Positions which operate other pieces of mechanical equipment used in high­way, canal, grounds and structural repair and maintenance are classified in the Highway Maintenance Worker title series Occ Code 6933100. Positions of Tractor Trailer Operator are described in Occ Code 7614000.

 

CORE DRILL OPERATOR operates a core drill apparatus to take samples of finished concrete or bituminous pavement or from a concrete structure: takes necessary measurements to locate points where cores are to be taken; if a sample indicates inadequate or defective pavement, takes additional samples nearby; labels cores with appropriate markings and ships the sample to the District Office; main­tains work activity reports; oils, greases and maintains the drilling equipment and the truck. He supervises a Laborer assigned to assist him on a project-to-project basis. QUALIFICATIONS: Although competitive examinations are not held for this class, candidates must possess a license to operate a motor vehicle in New York State and must have had one year of experience operating mobile power-driven equipment or machinery.

 

 

Reviewed:  4/03

 

NOTE:  Classification Standards illustrate the nature, extent and scope of duties and responsibilities of the classes they describe.  Standards cannot and do not include all of the work that might be appropriately performed by a class.  The minimum qualifications above are those which were required for appointment at the time the Classification Standard was written.  Please contact the Division of Staffing Services for current information on minimum qualification requirements for appointment or examination.