"The Pinnacles National Monument is located in San Benito and Monterey Counties about 130 highway miles south of San Francisco, California. Because of unusual patterns in volcanic rocks, the Monument was set aside as a recreation area on January 16, 1908, by President Theodore Roosevelt. It encompasses an area of approximately 12,818 acres.
Water quality and supply problems were experienced at the Monument in the few years prior to 1961. In 1961, a collection trench system was installed to alleviate the water supply condition. A horizontal trench system, 215 feet long and four feet below the dry season water table, was installed in the creek bed of Chalone Creek.
Driven well-points were used to determine fluctuations of the water level under pumping conditions. The use of well-points in a coarse alluvium, such as Chalone Creek alluvium, is not recommended by the author. Only 8 out of 18 well-points were successfully installed. Ripped screens in the well-points and bent pipe strings were the chief reasons for lack of success.
A channel sample was collected from the alluvium to determine the laboratory coefficient of permeability. The value was determined to be 5.5 x 102 gal/day/ft2. A mechanical analysis was conducted on the channel sample giving a mean grain size of 16mm,sorting coefficient of 6.7, phi skewness value of 0.6, and phi kurtosis of 0.33.
A pumping test was conducted to determine the field permeability and transmissibility of the Chalone Creek alluvium. It was calculated to have a permeability of 6.3 x 102 gal/day/ft2. The transmissibility was calculated as 3.2 x 104 gal/day/ft. The storage coefficient of the aquifer was determined to be .029.
Chemical analysis of water samples from Chalone Creek and Willow Spring, the largest of three springs in the area, indicated the quality of water is good for drinking purposes.
Utilization of the horizontal trench collection system should adequately supply the water demands of the Monument. Calculations indicate the trench could be pumped at a rate of 75 gal/min. for 1000 days without lowering the water table more than four feet"--Abstract, pages ii-iii.
Maxwell, James C.
Spreng, Alfred C., 1923-2012
Gevecker, Vernon A. C., 1909-1992
Muir, Clifford D.
Geosciences and Geological and Petroleum Engineering
M.S. in Geology
Missouri School of Mines and Metallurgy
vii, 86 pages
Chalone Creek, California
© 1962 Donald Lee Brown, All rights reserved.
Thesis - Open Access
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Electronic OCLC #
Link to Catalog Record
Brown, Donald Lee, "Investigation and development of ground water of Chalone Creek, (Pinnacles National Monument, California)" (1962). Masters Theses. 2725.