A. A down-gradient analysis shall be required for all high risk sites unless waived by the Director. The analysis is meant to identify and evaluate down-gradient adverse impacts that could result from the proposed development. Common adverse impacts of land development may include erosion, flooding, slope failures, altered runoff patterns, increased presence of groundwater, or reduced groundwater recharge (to springs, streams, wetlands, and wells, etc.) Site disturbance plans shall be designed to mitigate adverse impacts identified in the down-gradient analysis. Typically, the analysis should extend 500 feet down gradient and may be limited in scope by lack of access to adjacent properties.
B. If there are existing or potential off-site drainage problems down-gradient of the development, it shall be demonstrated that the proposed stormwater disposal system has been designed to meet all of the following conditions:
1. The stormwater runoff leaves the site in the same manner as that of the pre-developed condition;
2. Reduced or increased groundwater recharge has been considered with respect to potential adverse impacts on the down-gradient features; and
3. The proposed design does not aggravate an existing drainage problem or create a new drainage problem. (Ord. 546, 10-17-2019)