Wednesday, January 16, 2008

Coastal Stormwater Rules - Environmental Management Commission

Jan. 10 – As expected, the Environmental Management Commission approved an amendment to the state’s coastal stormwater rules this week. The rules will now go before the Rules Review Commission on February 21st; it is expected that they will then be forwarded to the General Assembly for legislative review. If no action is taken by the General Assembly, the rules could be effective as early as August 2008.
The rules have been revised somewhat from what was presented for public hearing back in the fall; attached is a copy of the rules that were approved. Check out the state’s website for more information about the rules http://h2o.enr.state.nc.us/su/coastal.htm. These rules affect ALL LAND in the twenty coastal counties!
Summary:
The new rules require a stormwater permit for non-residential development of over 10,000 sq. ft. land disturbance and a stormwater permit for residential development of over one acre of land disturbance. The following is also included under this provision:
o Vegetative buffers of 50 ft. for new development, 30 ft. for redevelopment.
o All wetlands will be excluded from will be excluded from impervious surface area calculations.
o When structural stormwater controls are required, they must discharge the storage volume at a rate equal or less than pre-development discharge rate for the 1-year, 24-hour storm. For controls that require separation from the seasonal high-water table, a minimum separation of two feet is mandated with at least 12 inches of naturally occurring soil above the seasonal high-water table. (Look out Hatteras!)
o If within ½ mile of SA (shellfishing) waters and built-upon area is greater than 12% (high density), structural stormwater control systems must be installed. They can consist of infiltration systems, wet detention ponds, bioretention systems, constructed stormwater wetlands, sand filters or other alternative stormwater management systems. Whether low or high density and within ½ mile of SA waters, no new points of stormwater discharge or increase in stormwater discharge to the waters will be allowed; stormwater discharge cannot flow beyond the property boundary.
o If outside of ½ mile of SA waters and built-upon area exceeds 24%, structural stormwater systems must be installed to store, control and treat runoff generated by one and one-half inch of rainfall.

The rules also include provisions if you do not fall under the permitting threshold as described above but have residential development activities with over 10,000 sq. ft. of land disturbance (which covers just about any development project) AND have more than 12% built-upon area within ½ mile SA waters/greater than 24% built-upon area outside of SA waters. They include:
o Within ½ mile SA waters, you must collect rooftop runoff form the one-year, 24-hour storm. You can install rains cisterns or rain barrels and use pervious materials or pervious pavement on all uncovered: driveways, parking areas, walkways and patios. You can also direct rooftop runoff to a rain garden and then use pervious materials on all to-be-paved surfaces. This provision also allows the installation of any other stormwater best management practice.
o Outside of SA waters, you must collect or direct rooftop runoff from the first one and one-half inch of rainfall. You can use the same methods as described within ½ mile of SA waters.

FYI: Built-upon area is defined as that portion of a project that is covered by impervious or partially impervious surface including, but not limited to, buildings; pavement and gravel areas such as roads, parking lots, and paths; and recreation facilities such as tennis courts. "Built-upon area" does not include a wooden slatted deck, the water area of a swimming pool, or pervious or partially pervious paving material to the extent that the paving material absorbs water or allows water to infiltrate through the paving material.

We are continuing to monitor this issue. As you are already aware, these rules are going to have a big impact on the cost of new development and just what you may be able to do with your property.

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