The reason for stagnant water in artificial grass turf field

In some artificial grass field or gass turf application, there are stagnant water there and it is not so easy to clear, then why these stagnant water is kept there? The following is the main reason for that, 1) The artificial grass turf field base is not well processed, the base field is uneven and result in the stagnant water there. 2) The artificial grass turf field was not maintained periodical, then the turf field became hardened and the drainage system was blocked so that the water can not be drained normally. 3) Partial artificial grass fibers are badly damaged and the grass turf field is full of bumps and hollows where water can be easily reserved. 4) Infillings are not well-proportioned arranged. If you find reserved water among artificial grass turf field, check the field based on the last four reasons and deal with it accordingly.