All ground areas of the lot occupied by the facility that are not utilized for access to operate and maintain the installation, for berms and landscaping, for existing additional principal uses on the lot, or for agricultural uses, or that will remain forested, shall be planted and maintained with shade tolerant grasses for the purpose of soil stabilization. A seed mixture of native, noninvasive shade-tolerant grasses shall be utilized and specified in the landscaping plan. If it can be demonstrated by the applicant that an alternative vegetative ground cover consisting of a seed mix of native, noninvasive plant species and nonnative, noninvasive shade-tolerant species is acceptable for soil erosion control and soil stabilization and can be better sustained over the life of the facility, the approving authority may approve such an alternative to the requirement for native, noninvasive shade-tolerant grass mix. The use of stone, gravel, wood chips or shavings or any artificial material shall not be permitted for soil erosion control and soil stabilization. If land having a slope of greater than 20% is proposed to be disturbed, additional soil erosion and sediment control measures may need to be implemented, and shall be subject to approval, based upon the recommendations of the Township Engineer.