RESULTS OF TRACER TESTS IN ROCK-PLANT FILTERS

Most commonly used design procedures for rock-plant filters (RPFs) assume the hydraulic regime to be plug flow. However, an increasing number of investigators now believe this assumption to be an oversimplification. The purpose of this research was to examine the flow pattern through two sets of filters: one set with an L:W ratio equal to 5:1 and the other with an L:W ratio of 1:5. The RPFs used for this research study are located on Interstate 49 near Grand Prairie, Louisiana. These filters were built by the Louisiana Department of Transportation and Development as an inexpensive, low-maintenance method for treating waste from a newly constructed rest area and also to research their feasibility for possible use at other interstate rest areas. Tracer tests were used to determine mean detention time and dispersion number (D/ul), a measure of departure from plug flow, for each cell. Results showed that the "long" cells (large L:W ratio) exhibited an intermediate amount of dispersion whereas the wide cells (low L:W ratio) exhibited a large amount of dispersion. The flow in the wide cells appeared substantially two-dimensional in nature. The effects of two-dimensional flow are manifested as dispersion when analyzed using one-dimensional equations. Thus, the value of a dispersion number computed from tracer data assuming one-dimensional flow is dependent, in part, on the L:W ratio of the cell. In this study, the wide cells produced higher dispersion numbers than the long cells even when the detention times were approximately equal.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/oclc/8675387
• Corporate Authors:

  American Society of Civil Engineers

  345 East 47th Street
  New York, NY  United States  10017-2398
• Authors:
  • Bhattarai, R B
  • Griffin Jr, D M
• Publication Date: 1999-2

Language

• English

Media Info

• Features: Appendices; Figures; References; Tables;
• Pagination: p. 112-125
• Serial:
  • Journal of Environmental Engineering
  • Volume: 125
  • Issue Number: 2
  • Publisher: American Society of Civil Engineers
  • ISSN: 0733-9372
  • Serial URL: http://ojps.aip.org/eeo

Subject/Index Terms

• TRT Terms: Chemical dispersions; Chemical tracers; Detention; Dyes; Filters; Flow; Hydraulics; Interstate highways; Plants; Roadside flora; Roadside rest areas; Rocks; Tests; Wetlands
• Geographic Terms: Louisiana
• Subject Areas: Geotechnology; Highways; Hydraulics and Hydrology; Terminals and Facilities; I26: Water Run-off - Freeze-thaw;

Filing Info

• Accession Number: 00759726
• Record Type: Publication
• Files: TRIS
• Created Date: Feb 11 1999 12:00AM