A Guide to
Drainage
FOLLOW US ONLINE TWITTER.COM/RUGBYCLUBMAG
It is worth stating that as the name says slits
and bands are ‘secondary’ drainage – they overlay
and link to a primary piped drainage system.
This needs emphasising because sand slits
and gravel bands are often thought to be stand
alone drainage schemes. By themselves they will
temporarily alleviate a surface water problem for a
short while but if there is nowhere for the water to
go they will soon cease to function.
Sand slits and gravel bands are installed at right
angles to the pipe and intercept the permeable
backfill above the pipe to provide a connection to
the piped system. Their purpose is to provide a
more speedy short cut for surface water to reach
the piped drainage system rather than going
through the soil. This is why they are sometimes
referred to as ‘by-pass’ systems because they bypass the soil, transporting surface water direct to
the drainage system and thus to an outfall.
DRAINAGE LAYOUT
16 Issue 67
Traditional layout for drainage schemes was the
‘herringbone’ with a centre main drain and laterals
running off it an angle like the backbone of a fish
which is why it got its name.
Though it is still used, a grid system is now
more common especially in sportsturf drainage. In
any drainage scheme wherever there is a junction
between a lateral and a main drain there is more
concentration of pipe at that point and more
permeable backfill over the pipe and around the
junction. Hence there is a higher rate of drainage
at that point which results in uneven plant growth.
In some situations this doesn’t matter but in
sportsturf if you use a herringbone layout with the
main drain running down the centre of a pitch, or
fairway, this uneven grass growth will be clearly
visible in certain conditions. So aesthetically it is
not pleasing, also it is more expensive in time and
materials because there are more junctions and
shorter runs of laterals for a given area.
This is why a grid system is more common for
sportsturf areas. The main drain can be positioned
off the playing surface. For pitches this can be
beyond the side-line, for golf courses this can be