We had new concrete front steps installed a few weeks ago. There are 10 steps running up the slope with bushes on both sides of the steps and pachysandra on the hill. We have had a few heavy rains since the installation and the water has run down the outer sides of the steps following the channels made by the wooden forms. The soil has eroded along the sides of the steps as well as underneath the outer edges of the steps about 6 inches in. How do I stop further erosion and fill in underneath the steps where the soil has washed away?