The purpose of this report is to present further substantiation of the filter readjustment hypothesis, to compare the action of corrugated metal subdrains with perforations located at the top of the pipe with drains having the holes at the bottom of the pipe, and to indicate the hydraulic capacity of various types of subsurface drain pipes. Principal conclusions obtained from the present test program include: 1. Initial compaction is a major factor in the development of filter stability. Over- compaction of a concrete sand filter may lead to failure of the bed, and will materially reduce the infiltration capacity of the system. 2. Stability of the filter at the pipe opening is not established by washing out the fines and bridging of the remaining large particles. Stability is established by the binding of pore spaces near the opening with fine particles which were moving toward the opening. 3. Corrugated metal subdrains should be installed with perforations at the bottom of the pipe for maximum security from filter failure. 4. Concrete sand may suitably be used as filter material with either clay drain tile or plastic pipe if the conduit is properly installed.

Media Info

  • Features: Figures; References;
  • Pagination: 16 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00083044
  • Record Type: Publication
  • Source Agency: Association of American Railroads Research Center
  • Report/Paper Numbers: #ER-29
  • Files: TRIS
  • Created Date: Mar 26 1975 12:00AM