There is a maximum impervious surface requirement in most zoning districts that cannot be exceeded. However, in the Open Space zoning district, the impervious surface coverage can be increased from 20% to 25% if there is mitigation. One possible mitigation strategy would be to install a professionally designed and City approved rain garden. Also, if a project creates more than 6,000 square feet of impervious surface area a Valley Branch Watershed District permit will be required which also may require a rain garden. Below you will find links to rain garden information.