Wick assembly and method for installing an underdrain

Abstract

A wick assembly for installation under a roadway according to the invention includes a perforated drain pipe, an inner sheet of a wicking fabric disposed on the perforated drain pipe in a manner effective to cover the perforations therein, an outer sheet of a wicking fabric, and a layer of filter aggregates confined between the inner and outer wicking fabric sheets to form a wick drain in combination with the perforated drain pipe. Water passes through the sheets and filter aggregates in order to enter the perforated drain pipe through the perforations therein. The wick drain may be disposed inside an outer pipe with the outer fabric sheet in slidable contact with the inner periphery of the pipe casing. The outer pipe casing serves to protect the wick drain during installation and is later removed once the wick drain is in position.

1 . A wick assembly for installation under a roadway, comprising:
 a perforated drain pipe;   a first sheet of a wicking fabric disposed on the perforated drain pipe in a manner effective to cover the perforations therein;   a second sheet of a wicking fabric; and   a layer of filter aggregate disposed between the first and second wicking fabric sheets to form a wick drain in combination with the perforated drain pipe to allow water to pass through the sheets and filter aggregates in order to enter the perforated drain pipe through the perforations therein.   
     
     
         2 . The wick assembly of  claim 1 , further comprising one or more lengthwise seams at which the first and second sheets are secured together, subdividing the layer of filter aggregate into a plurality of lobes. 
     
     
         3 . A method of forming a wick drain, the method comprising:
 sandwiching a layer of filter aggregate between a first sheet of fabric and a second sheet of fabric to form a wick layer;   wrapping the wick layer around a perforated drain pipe such that the wick layer covers the perforations therein; and   securing the wick layer to the perforated drain pipe.   
     
     
         4 . The method of  claim 3 , further comprising subdividing the filter aggregate into two or more partitions. 
     
     
         5 . The method of  claim 4 , wherein the two or more partitions are lobes defined between seams securing the first sheet to the second sheet along a lengthwise direction.