The recent wet winters have produced problems on many winter sports pitches. Often the first line of approach is to install an intensive pipe drainage scheme. Clubs commonly expect such a system to work immediately, to require limited maintenance and, worse still, are frequently forgotten about.
Problems often encountered following drainage installation.
Steve Gingell, STRI Southern Area Manager
POST DRAINAGE BLUES
• Poor drainage and compact surfaces
Each of these will be examined below and causes and solutions presented. Drain line subsidence
T
his article assesses the common problems often associated with new installations and attempts to provide some solutions. However, it is vitally important to gain advice from your consultant, as specific situations will require specific solutions.
The problems!
Typical issues and problems that occur are: • Drain line subsidence
• Difficulty to grow grass in the summer, especially over drain lines
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A frequent reason for subsidence is that clay soils can shrink in long spells of dry, late spring/summer weather. As this happens the drain trenches often get slightly wider and the backfill over the pipe settles, often creating a depression over the drain. Subsidence can be as much as 100-150mm but, more typically, is 25-50mm (see image 1). Sometimes, however, the material in the drain trenches settles as the trench widens due to soil shrinkage, but the turf on the immediate surface does not settle, thus leaving a void underneath. This can be a particularly worrying condition, as the first you may know about it is when someone’s foot goes through the surface into the underlying void, often sustaining
an injury in the process.
It must be pointed out that these are natural problems but, occasionally, there may be problems due to installation techniques or the use of inappropriate materials. Certainly, great care is needed to avoid settlement as a consequence of these inadequacies. The first solution to
settlement/subsidence is to top up the drain lines with a similar topdressing to the top 150mm of the drain. This should be targeted during the early summer (maybe on a few occasions) to allow regrowth of the grass over the drains. The application of irrigation during the summer to prevent or control the clay moisture content, and thus minimise settlement, is also an effective way forward. This should also help favour the development of good swards. However, in dry regions of the country, this could have a high cost, both financially and
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