Oak Island staff and the majority of the planning board are again asking town council to consider restricting the total amount of built-upon area for new single, two and three-family houses.
Council previously rejected a similar proposal and also a related suggestion that would have established guidelines for the tree canopy. Staff is revisiting the issue after multiple complaints about flooding following Hurricane Florence.
Development Services Director Steve Edwards said the idea is to limit the built-upon area to a maximum of 45-percent of the building lot. This measure would help control stormwater runoff, preserve open space and protect the water quality of creeks, the marsh and the ocean, he said.
A review of recent building permits showed the average built-upon area, also called the impervious surface, was 34.4-percent. The lowest among the 100 plans reviewed was 13.9-percent and the highest was 48.8-percent.
Edwards said one homeowner who was upset about flooding on her lot had a built-upon area of 67-percent.
“The goal of this text amendment is to mitigate runoff issues by restricting the amount of impervious surface that can be installed on a lot and to preserve open space,” a memorandum to council states.
“Generally, the more impervious surface on a lot, the more likely runoff/flooding issues (are) a problem.”
The change would require an engineered stormwater management system for new home construction that exceeds 30-percent of the lot size. Smaller homes would still require a stormwater plan, but not necessarily one prepared by a registered engineer.
Currently, the town requires an engineered system if impervious surfaces exceed 45-percent. The proposed change would set 45-percent as a maximum.
Impervious surfaces include buildings, pavement and gravel. Not included are wooden slatted decks and the water area of a swimming pool.
Some innovative designs can lessen the impervious surface area, such as tire runners with grass between them instead of a solid concrete or gravel driveway. Also excluded from the calculation is a surface with number 57 stone, laid at least four inches thick over geotextile fabric and porous concrete with a specific hydraulic conductivity.
The planning board voted 6-1, with Willie Williams dissenting, to recommend the proposal. After the meeting, Williams said he thought the 45-percent limit was too restrictive.
Neighboring Caswell Beach restricts the built-upon area to 30 or 36-percent, depending on the zoning district.
Town council is scheduled to consider the proposal at its regular June 11 meeting at 6 p.m.