I have a customer who had a tree removal service take down a 80' dead red oak. They left a giant version of a pitcher's mound composed of stump grindings. The mound's been there 8 months, been through this hellacious Michigan winter. Now the customer wants me to grow grass, or maybe some wildflowers there. I'm assuming the mound is too damn acidic for anything to grow. Any suggestions? Excavating the mound and replacing with soil is not an option ( too costly ). Thanks.