§ 25-8-63. IMPERVIOUS COVER CALCULATIONS.

(A)

Impervious cover is calculated in accordance with this Section and the Environmental Criteria Manual.

(B)

Impervious cover calculations include:

(1)

roads;

(2)

driveways;

(3)

parking areas;

(4)

buildings;

(5)

concrete;

(6)

impermeable construction covering the natural land surface;

(7)

for an uncovered wood deck that has drainage spaces between the deck boards and that is located over a pervious surface, 50 percent of the horizontal area of the deck; and

(8)

the portion of a site used for the storage of scrap and metal salvage, including auto salvage.

(C)

Impervious cover calculations exclude:

(1)

sidewalks in a public right-of-way or public easement;

(2)

multi-use trails open to the public and located on public land or in a public easement;

(3)

water quality controls, excluding subsurface water quality controls;

(4)

detention basins, excluding subsurface detention basins;

(5)

drainage swales and conveyances;

(6)

the water surface area of ground level pools, fountains, and ponds;

(7)

areas with gravel placed over pervious surfaces that are used only for landscaping or by pedestrians and are not constructed with compacted base;

(8)

porous pavement designed in accordance with the Environmental Criteria Manual, limited to only pedestrian walkways and multi-use trails, and located outside the Edwards Aquifer Recharge Zone;

(9)

fire lanes designed as prescribed by the Environmental Criteria Manual, that consist of interlocking pavers, and are restricted from routine vehicle access;

(10)

an access ramp for an existing single-family and duplex residential unit if:

(a)

a person with a disability requires access to a dwelling entrance that meets the requirements of the Residential Code, Section R320.6 ( Visitable dwelling entrance );

(b)

the building official determines that the ramp will not pose a threat to public health and safety;

(c)

the ramp:

(i)

is no wider than 48 inches, except that any portion of a landing for the ramp required for turns may be no wider than 60 inches; and

(ii)

may have a hand railing, but may not have a roof or walls; and

(d)

the ramp is located in a manner that utilizes existing impervious cover to the greatest extent possible if:

(i)

impervious cover on the property is at or above the maximum amount of impervious cover allowed by this title; or

(ii)

if placement of the ramp would result in the property exceeding the maximum amount of impervious cover allowed by this title; and

(11)

a subsurface portion of a parking structure if the director of the Watershed Protection Department determines that:

(a)

the subsurface portion of the structure:

(i)

is located within an urban or suburban watershed;

(ii)

is below the grade of the land that existed before construction of the structure;

(iii)

is covered by soil with a minimum depth of two feet and an average depth of not less than four feet; and

(iv)

has an area not greater than fifteen percent of the site;

(b)

the structure is not associated with a use regulated by Section 1.2.2 of Subchapter F of Chapter 25-2 ( Residential Design and Compatibility Standards );

(c)

the applicant submits an assessment of the presence and depth of groundwater at the site sufficient to determine whether groundwater will need to be discharged or impounded; and

(d)

the applicant submits documentation that the discharge or impoundment of groundwater from the structure, if any, will be managed to avoid adverse effects on public health and safety, the environment, and adjacent property.

Source: Subsections 13-2-595 (a), (b), and (g); Ord. 990225-70; Ord. 000406-85; Ord. 010329-18; Ord. 031211-11; Ord. 20060831-068; Ord. 20131017-046; Ord. No. 20140522-078, Pt. 2, 6-2-14 ; Ord. No. 20170615-102 , Pt. 12, 6-15-17.