A good article on Quarry Operations:

Limestone & Dolomite Resources of California (as of 1973)

Excerpts from

The Mineral Economics of The Carbonate Rocks: Limestone and Dolomite Resources of California,
Bulletin 194, by Oliver E. Bowen, Cliffton H. Gray, Jr., and James R. Evans,
California Division of Mines and Geology, Sacramento, 1973.

“Mining, Processing and Beneficiating Carbonate Rocks in California,” by Oliver E. Bowen, James R. Evans, and Clifton H. Gray, Jr. (Chapter 3, pp. 29-33)

“Unlike the middle west or southwest parts of the United States, California has few flat or nearly flat-lying limestone-bearing formations. More often than not, California limestone bodies are thick, rather structureless masses, unmarked by distinctive horizons and somewhat variable in Chemistry. Commonly, such bodies are mined en masse, and the problems of chemical variation are ovecome (sic) by blending the various grades of rock. Igneous intrusions and interbeds of rock of non-carbonate character often necessitate considerable selectivity during quarrying. Land-surface relief is often considerable and in some cases extreme. Consequently, one cannot mine a few select beds of rock over large acreages. Five deposits currently are mined underground (circa 1973) – one to an inclined depth of 1300 feet. One major cement plant is supplied almost wholly by underground mining.

Acquisition of Mineral Properties

“Many deposits of carbonate rock are privately owned, title to these deposits having passed from public to private ownership under various land and mining laws….”

Mining Methods

“Most California limestone and dolomite deposits are situated on hills where they can be readily quarried from level benches cut into the hillsides. In some places, however, it has been necessary to utilize pits sunk well below local base level, with resultant higher quarry costs. There are four large, and one small, underground mines from which limestone, dolomite, or both are obtained (circa 1973). At Davenport, Santa Cruz County, there is one large glory hole operation where the haulage ways and part of the rock-storage facilities are underground. Underground mines are found at: the Crestmore cement operation of American Cement Corporation, Riverside County; U.S. Lime Products Division of The Flintkote Company, Sonora, Tuolumne County; the El Dorado Limestone Company, Shingle Springs, El Dorado County; the Diamond Springs Lime Company near Auburn, El Dorado county; and the dolomite operation of Premier Marble Products near Keeler, Inyo County. Other underground mines have operated intermittently at Felton, Santa Cruz County, and near Keeler, southeast of Premier’s operation. Diamond Springs Lime Company’s mine was originally a glory hole operation under a previous operator.

“With a few exceptions, California limestone and dolomite deposits are so tenacious that blasting is required to break the rock into fragments of suitable size for handling and processing. Two notable exceptions are the Skyline limestone deposit near Crystal Springs Lakes in San Mateo County (currently inactive) (circa 1973) and the Westvaco dolomite deposit near Hollister in San Benito County. At both of these deposits, the rock has been shattered by faulting in the San Andreas fault zone, so that little or no blasting is required to break the rock.

Quarrying

“In common bench-quarrying practice in California, 20-, 30-, and 50-foot or even larger bench spacings (vertical distance between floor levels or height of the working face) are adopted, depending upon the topography, distribution of various grades of rock in the deposit, safety factors, and other considerations. A line of holes commonly is drilled at a suitable distance back of the working face, from the top of the face down to the approximate level of the quarry floor. The spacing of these holes and the distance from the working face is dependent upon the type of explosive being used, the breaking strength of the rock the degree of fragmentation desired, and other related factors. The diameter of the holes ranges from three inches to more than nine. Explosives manufacturers are continually improving explosives and blasting practice, which are adaptable to the needs of producers of carbonate rocks. Development and use of drill rigs capable of making large inclined blast holes in a renewed application of principles known since 1918. Some companies are contracting most of their blasting operations to explosives companies.

 Transportation

“Rock is transported from the quarry to the processing plant by truck. The trend is toward larger capacity rigs except for smaller operations. Skip loaders accomplish loading. Among new installations, the trend has been toward establishing primary and secondary crushing installations, chute-loading facilities and some sizing (screening) installations close to the quarries.