Controlling sediment

Abstract

Sediment control devices include a planar apertured threshold member, a planar apertured outflow member, and a planar filter member between the threshold and outflow members. The members lie in parallel planes, and there is substantially no hollow space between the threshold member and the outflow member.

1 . A sediment control device (SCD) which comprises
 (1) a substantially planar elongate threshold member,   (2) a substantially planar elongate outflow member, and   (3) a substantially planar elongate filter member between the threshold and outflow members,   
       the threshold, outflow and filter members lying in parallel planes and being secured together so that there is substantially no hollow space between the threshold member and the outflow member, 
       each of the threshold and outflow members being apertured sheet materials having multiple relatively large apertures therethrough, the apertures having an area of 0.01 to 1.0 in. 2 , and 
       the filter member having a mesh size of 80 to 600 micron. 
     
     
         2 . A sediment control device according to  claim 1  wherein each of the threshold member and the outflow member is composed of a multiplicity of polymeric strands. 
     
     
         3 . A sediment control device according to  claim 1  wherein the apertures in the threshold member are the same size as the apertures in the outflow member. 
     
     
         4 . A sediment control device according to  claim 3  wherein the threshold member and the outflow member are different parts of a single piece of apertured polymeric material. 
     
     
         5 . A sediment control device according to  claim 1  wherein the apertures in the outflow member have a size which is less than 0.45 times the size of the apertures in the threshold member. 
     
     
         6 . A sediment control device according to  claim 1  wherein the apertures in the threshold and outflow members have an area of 0.02 to 0.25 in. 2 . 
     
     
         7 . A sediment control device according to  claim 1  which comprises
 (a) a first substantially planar portion and 
 (b) a second substantially planar portion which is coplanar with the first portion, and which comprises at least part of the threshold member, at least part of the outflow member, and at least part of the filter member. 
 
     
     
         8 . A sediment control device according to  claim 7  wherein the first portion consists of part of the threshold member, part of the outflow member, and part of the filter member; and the second portion consists of the remainder of the threshold member, the remainder of the outflow member, and the remainder of the filter member. 
     
     
         9 . A sediment control device according to  claim 7  wherein the first portion consists essentially of part of the threshold member and part of the outflow member; and the second portion consists of the remainder of the threshold member, the remainder of the outflow member, and all of the filter member. 
     
     
         10 . A sediment control device according to  claim 1  which, when subjected to a test which consists of
 (i) completely immersing the SCD in water for  0 . 5  hour, 
 (ii) removing the SCD from the water, 
 (iii) placing the_SCD on a horizontal apertured surface, and 
 (iv) leaving the SCD to drain for 0.5 hour in still air at 20° C., has a weight after the test which is not more than 1.1 times the weight of the SCD before the test. 
 
     
     
         11 . A sediment control device according to  claim 1  which, when subjected to a test in which clean water is directed towards the SCD at right angles to the threshold member, is capable of passing 200-400 gallons of water per square foot per minute of the area of the threshold member, and the volumes of water entering and leaving any particular length of the SCD do not differ by more than 20%, based on the volume of water entering the particular length of the SCD. 
     
     
         12 . A sediment control device (SCD) which consists essentially of
 ( 1 ) a substantially planar elongate threshold member,   ( 2 ) a substantially planar elongate outflow member, and   ( 3 ) a substantially planar elongate filter member between the threshold and outflow members,   
       the threshold, outflow and filter members lying in parallel planes and being secured together so that there is substantially no hollow space between the threshold member and the outflow member, 
       each of the threshold and outflow members being composed of an apertured sheet material comprising a multiplicity of polymeric strands and having multiple relatively large apertures therethrough, the apertures having an area of 0.01 to 1.0 in. 2 , and the filter member having a mesh size of 80 to 600 micron. 
     
     
         13 . A sediment control device according to  claim 12  wherein the apertures in the threshold member are the same size as the apertures in the outflow member. 
     
     
         14 . A sediment control device according to  claim 12  wherein the threshold member and the outflow member are different parts of a single piece of apertured sheet is material. 
     
     
         15 . A sediment control device according to  claim 12  wherein the apertures in the outflow member have a size which is less than 0.45 times the size of the apertures in the threshold member. 
     
     
         16 . A sediment control device according to  claim 12  wherein the apertures in the threshold and outflow members have an area of 0.02 to 0.25 in. 2 . 
     
     
         17 . A sediment control device according to  claim 12  which consists of (a) a first portion which consists of part of the threshold member, part of the outflow member, and part of the filter member, and (b) a second portion which is coplanar with the first portion and which consists of the remainder of the threshold member, the remainder of the outflow member, and the remainder of the filter member. 
     
     
         18 . A sediment control device according to  claim 12  which consists of (a) a first portion which consists essentially of part of the threshold member and part of the outflow member; and (b) a second portion which consists of the remainder of the threshold member, the remainder of the outflow member, and all of the filter member. 
     
     
         19 . A sediment control device according to  claim 12  which, when subjected to a test which consists of
 (i) completely immersing the SCD in water for 0.5 hour, 
 (ii) removing the SCD from the water, 
 (iii) placing the_SCD on a horizontal apertured surface, and 
 (iv) leaving the SCD to drain for 0.5 hour in still air at 20° C., has a weight after the test which is not more than 1.1 times the weight of the SCD before the test. 
 
     
     
         20 . A sediment control device according to  claim 12  which, when subjected to a test in which clean water is directed towards the SCD at right angles to the threshold member, is capable of passing 200-400 gallons of water per square foot per minute of the area of the threshold member, and the volumes of water entering and leaving any particular length of the SCD do not differ by more than 20%, based on the volume of water entering the particular length of the SCD.