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|Title:||Acid attack of concrete caused by sulphur bacteria action, Piedmont and Clendening Lakes outlet tunnels, Muskingum watershed, Ohio|
|Authors:||United States. Army. Corps of Engineers. Huntington District.|
Thornton, Henry T.
|Publisher:||Concrete Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||Miscellaneous paper (U.S. Army Engineer Waterways Experiment Station) ; C-77-9.|
Abstract: This investigation was conducted to determine the cause of extensive deterioration of concrete above the flow line in the outlet tunnels of two lakes, and to provide guidance in the development of remedial repair schemes if necessary. The cement paste was being reduced to a "mush" consistency to depths up to 1-1/4 in. Anaerobic bacterial action was indicated by preliminary tests. The program of investigation included: a. An extensive literature review on sulfur bacteria. b. Collection of water samples, deterioration products, and concrete cores at each site. c. Physical, chemical, and bacteriological testing of samples including identification of sulfate-reducing bacteria. d. Obtaining other pertinent data from Huntington District. Physical tests showed the original concrete to be of good quality and that some form of acid attack was in progress. Chemical tests revealed that the water contained high concentrations of sulfate& and sulfides. Bacteriological tests confirmed that sulfate-reducing bacteria were present. Data furnished by Huntington District reveal that thermal stratification occurs during the summer causing almost complete depletion of dissolved oxygen at depths greater than 20 ft in both lakes providing an environment where sulfate-reducing bacteria are able to reduce the sulfates present in the water, producing hydrogen sulfide as a waste product. Conditions in the outlet tunnels meet the criteria for the deposition and proliferation of sulfur-oxidizing bacteria which produce sulfuric acid from the hydrogen sulfide. It is concluded that the deterioration is due to acid attack and is the final stage of a corrosive process caused by sulfur bacteria action. Attack by acid water is not indicated, since all the deterioration occurs above the line of normal flow. Possible remedial measures including ventilation to remove the hydrogen sulfide, flushing the walls to remove the substrate, and raising the siphon intakes to draw water from above the sulfide-rich hypolimnion are offered for consideration for immediate implementation in both lakes. Further study will be necessary to determine the applicability of each of these remedial measures to the problem. It is also recommended that a long range program be formulated to deal with the problems produced by the high sulfate-sulfide concentrations in the lakes. Attention is drawn to the fact that there may be other structures undergoing this type of deterioration, and that the corrosion may be proceeding undetected.
|Rights:||Approved for public release; distribution is unlimited.|
|Appears in Collections:||Miscellaneous Paper|
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