07-24-2014, 02:44 PM
Recharge trenches are suitable for buildings having roof area of 200-300 sq.m. and where permeable strata is available at shallow depths.
Trench may be 0.5 to 1 m wide, 1 to 1.5m. deep and 10 to 20 m. long depending upon availability of water to be recharge.
These are back filled with boulders (5-20cm), gravel (5-10 mm) and coarse sand (1.5-2 mm) in graded form – boulders at the bottom, gravel in between and coarse sand at the top so that the silt content that will come with runoff will be coarse sand at the top of the sand layer and can easily be removed.
A mesh should be provided at the roof so that leaves or any other solid waste/debris is prevented from entering the trenches and a desilting/collection chamber may also be provided on ground to arrest the flow of finer particles to the trench.
By-pass arrangement be provided before the collection chamber to reject the first showers.
The top layer of sand should be cleaned periodically to maintain the recharge rate.
![[Image: harvesting1.png]](http://www.frontdesk.co.in/big/bs/harvesting1.png)
Trench may be 0.5 to 1 m wide, 1 to 1.5m. deep and 10 to 20 m. long depending upon availability of water to be recharge.
These are back filled with boulders (5-20cm), gravel (5-10 mm) and coarse sand (1.5-2 mm) in graded form – boulders at the bottom, gravel in between and coarse sand at the top so that the silt content that will come with runoff will be coarse sand at the top of the sand layer and can easily be removed.
A mesh should be provided at the roof so that leaves or any other solid waste/debris is prevented from entering the trenches and a desilting/collection chamber may also be provided on ground to arrest the flow of finer particles to the trench.
By-pass arrangement be provided before the collection chamber to reject the first showers.
The top layer of sand should be cleaned periodically to maintain the recharge rate.