I have three very old Weeping Willows that sit in a low wet area. The water table fills a small pond at their base from October to May. The area is also medium traffic to horses and people. We have put in drainage to direct the water away, (we hope) and have put new soil about 1 to 2 feet thick around them. The total area of the three is close to 75 feet long and 25 wide as they are in a row. We are resoiling the entire area in hopes to create a slope to redirect water as well. We were told that putting soil at the base of willows will not harm them. I would like to know if this is true and if it is not, what can be done without harming them?