CFE agenda 051115 - Laserfiche WebLink

Browse Search

Attachment 1 Harvey said under certain circumstances the State of North Carolina allows a larger area of impervious surfaces on a property through the installation and continued maintenance of on -site stormwater retention measures, such as permeable pavement. Such a device would be designed to capture runoff and allow it to infiltrate the soil. Harvey said permeable pavement is not counted as totally impervious, which translates to an allowance for installing additional "impervious surface area." Harvey said the board of county commissioners has directed Planning staff to evaluate how the County might incorporate language similar to what the State uses for the treatment of permeable pavement in its impervious surface calculations. He said the County considers gravel, asphalt, and concrete, along with more impenetrable building surfaces (roofs, etc.), within its current definition of impervious surfaces. Harvey said the proposed amendment to County rules would allow permeable concrete and some other permeable surfaces to be counted as 50 percent toward the impervious surface area. The County would require an engineer to certify there would be no net increase in the stormwater runoff leaving the property. The County would also require an operations agreement be signed and recorded at the Orange County Registry. The County would also require there be annual inspections and reporting of maintenance. Finally, Harvey said the County would obtain a permanent access easement to the property in order for staff to monitor and enforce the UDO standards. Harvey said it is his impression that a property with 8% impervious cover that includes certain best management practices would result in less stormwater runoff than a property with 6% impervious cover. Craig Benedict (Orange County Planning Director) noted that the current watershed overlay districts were established in 1994 and in many areas of the county the standards are more stringent that the State guidelines for watershed protection areas. He agreed with Harvey that the intent of the rule change was for there to be no net increase in stormwater runoff from any permitted site. Harvey and Benedict responded to questions from CFE members • Hintz noted that such devices always fail at some point. Harvey said the County would require a binding operations and maintenance agreement, and possibly also a letter of credit with no expiration date. • Davis asked what would happen if a device failed after 10 years. Harvey said the County would issue a notice of violation. If the landowner did not take corrective action the County would remediate the site at the owners' expense. • Welch asked what difference do 6% and 12% impervious limits have on water quality. Harvey said he feels the proposed allowance of increased impervious surfaces in the form of permeable concrete would not harm water quality. Benedict added that Orange County is the most restrictive in the state in terms of watershed protection. • Becker asked what motivated the County is pursuing this amendment. Benedict said many residents had complained that the rules are too stringent in some watersheds, notably the University Lake, Little River, and Cane Creek overlay districts. He explained how quickly 6% of a property could be covered with impervious surfaces — especially if roads and driveways are included. Benedict said he did not expect a lot of extra staff time would be required to implement the proposed rule change. 3