Mcallen Daily Press

State Highway Department Acquires New Divining Rod To Locate Valuable Deposits

AUSTIN, Aug 19 - Recently an electrical instrument for determining natural formations of the earth to depths of 100 feet or more below the ground surface has been developed by the Public Roads Administration. The Texas Highway Department has been experimenting with the use of this instrument on Texas for locating hidden deposits of caliche gravel and rock, suitable for pavement base courses, and is effecting economies through the use of it. Hidden deposits of suitable materials have been found adjacent to construction projects, and where they were not previously known to exist. This instrument with its accessories, as developed, is easily transported as an engineer's transit or level, and with practice can be operated rapidly.

Examples of savings which have been made with the aid of this electrical resistivity instrument are as follows.

In one district a search by digging test holes had uncovered no suitable material in the vicinity of the project and it appeared that base material would have to be hauled quite a long distance. A search then was started with the electrical resistivity instrument and a large deposit of suitable material was located only one-half mile from the highway project. It is estimated that $5,150 in haul was saved by the finding of this local deposit with the electrical instrument.

On construction where the nearest known deposits of gravel for pavement base courses was 10 miles to the north. Sub-surface explorations with the electrical resistivity instrument revealed an abundance of concealed road gravel 2 miles from the highway. The difference between the cost of the 10-mile gravel haul and the 2-mile haul was $1150.00 per mile of highway to the bidder.

During the latter part of June 20000 cubic yards of base material were loaded on a contract where each material had been tested and a material saving was affected over the cost of shipping materials from another source.