Sometimes the drain pipe behind your retaining wall must be raised to accommodate outlets through the wall face. A shelf of low permeable granular soils, level with finished grade should then be created to prevent water from ponding below grade. See Allan Block Design Detail #4 – Alternate Drain, in the Allan Block Spec Book.
Drain pipes existing to daylight through the wall should be installed with rodent screen to prevent nesting within the pipe. Blocks can be cut to allow for installation of a manufactured drain cover, or Wall Drain Pro could be used without the requirement of cutting block. (ref. BP, Chapter 4.1)
Allan Block is working to achieve our industry initiative of Zero Wall Failures. With our Best Practices Manual and experience in the industry we are trying to expand the knowledge base for the design of segmental retaining walls (SRW's) by communicating and educating the professionals in the industry. To see the full Best Practices Manual, visit allanblock.com to download today and keep an eye out for more industry Best Practice recommendations here.