Q.leaves dropping in an aggressive fashion
I am a beginner landscaper with my own business just starting a year ago. A good client of mine was very sick in Nov and Dec and I was in need of dirt for the tree wells due to showing roots from the majority of 7 hedges 13 diff. trees. I added pure sand from the sand wash and am I ever paying for it now. How can I balance back out the soil and fast? I have lost one evergreen hedge already and fear 2 more are not far behind. Also, 1 of 2 fruitless mulberry leaves are turning pale yellow and looks terrible. Please help!

The sand is not able to sustain your tree and shrub plantings.
You would need to dig and amend with compost and adequate soil.
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/amending-sandy-soil.htm