2″ of rain and drainage worked

We had two inches of very hard rain last night and our Fairview drainage solution worked like a charm.  I spoke with the neighbor and he said that when they had rains all of the water and dirt from this area would cascade over the wall and into his pool by the wheel barrow full.  He checked it at two this morning (which shows how big a problem it was for him) and he had no dirt.  What’s the secret?  The water was following the RR tie retaining wall making a river to the pool.  Instead of installing drainage pipes, we installed 4″ river rock.  The water still follows the same path but the rock puts the brakes on its speed and lets it filter to other areas.