The purpose of this article is to establish impervious surface
standards to protect water quality and fish and wildlife habitat and
to protect against pollution of navigable waters. County impervious
surface standards shall apply to the construction, reconstruction,
expansion, replacement or relocation of any impervious surface on
a riparian lot or parcel and any nonriparian lot or parcel that is
located entirely within 300 feet of the ordinary high-water mark of
any navigable waterway.
A.ย
Percentage of impervious surface shall be calculated by dividing the surface area of the existing and proposed impervious surfaces on the lot or parcel by the total surface area of that lot or parcel and multiplied by 100. Impervious surfaces described in ยงย 396-20 shall be excluded from the calculation of impervious surface on the lot or parcel. If an outlot lies between the ordinary high-water mark and the developable lot or parcel and both are in common ownership, the lot or parcel and the outlot shall be considered one lot or parcel for the purposes of calculating the percentage of impervious surface.
B.ย
For properties that have been "condominiumized" the impervious surface
calculations apply to the entire property. The property is still under
one legal description and the proposed expansion to a unit is not
the only impervious surface calculated since the regulation states
lot or parcel and not a unit. Mitigation applies to the property as
a whole and not just to the portion of the frontage that might be
in front of the unit impacted.
A property may exceed the impervious surface standard under ยงย 396-18 provided the following standards are met:
A.ย
Impervious surfaces that can be documented to demonstrate they meet either of the following standards shall be excluded from the impervious surface calculations under ยงย 396-17:
(1)ย
The
impervious surface is treated by devices such as stormwater ponds,
constructed wetlands, infiltration basins, rain gardens, bioswales
or other engineered systems.
(2)ย
The
runoff from the impervious surface discharges to an internally drained
pervious area that retains the runoff on or off the parcel and allows
infiltration into the soil.[1]
[1]
Editor's Note: Former Subsection B, regarding decks, which
immediately followed, was repealed 4-17-2019 by Ord. No. 8-2019.
For existing impervious surfaces that were lawfully placed when constructed but that do not comply with the impervious surface standard in ยงย 396-18 or the maximum impervious surface standard in ยงย 396-19, the property owner may do any of the following:
A.ย
Maintain and repair the existing impervious surfaces;
B.ย
Replace existing impervious surfaces with similar surfaces within
the existing impervious surface envelope; or
C.ย
Relocate or modify an existing impervious surface with similar or different impervious surface, provided that the relocation or modification does not result in an increase in the percentage of impervious surface that existed on the effective date of this chapter, and the impervious surface meets the applicable setback requirements in ยงย 396-9 or 396-11.
Note: The impervious surface standards in this chapter shall
not be construed to supersede other provisions in this chapter. All
of the provisions of this chapter continue to apply to new or existing
development.
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