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Title: ALKALINE LEACHATE AND CALCAREOUS TUFA ORIGINATING FROM SLAG IN A HIGHWAY EMBANKMENT NEAR BALTIMORE, MARYLAND
Accession Number: 00666223
Record Type: Component
Availability: Find a library where document is available Abstract: A series of springs located along the lower contact of a slag bed 3 to 7 m thick sandwiched within an embankment for Interstate 695 in Baltimore County, Maryland, discharges water with a pH of 12.5 to 13 and a dissolved calcium concentration of roughly 1000 mg/L. Further reactions with atmospheric CO2 cause this leachate to precipitate copious quantities of calcite (CaCO3) in the form of surficial tufa, interstitial cement within the fill, or fine powdery sediment in surface water. Because of its high pH, the leachate is classed as a hazardous waste, and the Maryland State Highway Administration has been required to construct a fenced enclosure and containment pond for the springs and to haul away the leachate or treat it before discharge. The cost of remediation had reached $1,000,000 by early 1994, when a treatment plant using hydrochloric acid to neutralize the leachate was about to begin operation. This case history demonstrates that great caution should be exercised in use of industrial by-products as construction materials. Although other recent studies have clarified the mechanism of tufa formation, unanswered questions remain regarding the mobility and fate of labile constituents other than calcium. Such questions must be answered before such reactive materials are dispersed into the environment in the name of recycling.
Supplemental Notes: This paper appears in Transportation Research Record No. 1434, Subsurface Drainage, Soil-Fluid Interface Phenomena, and Management of Unpaved Surfaces. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved
Monograph Title: Subsurface drainage, soil-fluid interface phenomena, and management of unpaved surfaces Monograph Accession #: 01401242
Language: English
Authors: Boyer, Bruce WPagination: p. 3-7
Publication Date: 1994
Serial: ISBN: 0309055113
Features: Figures
(1)
; References
(10)
; Tables
(2)
TRT Terms: Uncontrolled Terms: Subject Areas: Environment; Finance; Geotechnology; Highways; Materials; I33: Other Materials used in Pavement Layers; I42: Soil Mechanics
Files: TRIS, TRB
Created Date: Sep 16 1994 12:00AM
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