§ 30-5-281. CRITICAL ENVIRONMENTAL FEATURES.

(A)

Drainage patterns for proposed development must be designed to protect critical environmental features from the effects of runoff from developed areas, and to maintain the catchment areas of recharge features in a natural state. Special controls must be used where necessary to avoid the effects of erosion, or sedimentation, or high rates of flow.

(B)

A residential lot may not include a critical environmental feature or be located within 50 feet of a critical environmental feature.

(C)

This subsection prescribes the requirements for critical environmental feature buffer zones.

(1)

A buffer zone is established around each critical environmental feature described in this subchapter.

(a)

Except as provided in Subsection (C)(1)(b), the width of the buffer zone is 150 feet from the edge of the critical environmental feature.

(b)

For a point recharge feature, the buffer zone coincides with the topographically defined catchment basin, except that the width of the buffer zone from the edge of the critical environmental feature is:

(i)

not less than 150 feet;

(ii)

not more than 300 feet; and

(iii)

calculated in accordance with the Environmental Criteria Manual.

(2)

Within a buffer zone described in this subsection:

(a)

the natural vegetative cover must be retained to the maximum extent practicable;

(b)

construction is prohibited; and

(c)

wastewater disposal or irrigation is prohibited.

(3)

If located at least 50 feet from the edge of the critical environmental feature, the prohibition of Subsection (C)(2)(b) does not apply to:

(a)

a yard or hiking trail; or

(b)

a recharge basin approved under Section 30-5-213 ( Water Quality Control Standards ) that discharges to a point recharge feature; or

(c)

an innovative runoff management practice approved under Section 30-5-151 ( Innovative Management Practices ).

(4)

Perimeter fencing with not less than one access gate must be installed at the outer edge of the buffer zone for all point recharge features. The fencing must comply with the Standard Specifications Manual.

(5)

The owner must maintain the buffer zone in accordance with standards in the Environmental Criteria Manual to preserve the water quality function of the buffer.

(D)

When voids in the rock substrate are uncovered during development, the following protocol must be followed:

(1)

construction in the area of the void must cease while the applicant conducts a preliminary investigation of the void as prescribed by the Environmental Criteria Manual.

(2)

The applicant shall contact a City of Austin Environmental Inspector to schedule further investigation by the City of the void as prescribed by the Environmental Criteria Manual if the preliminary investigation indicates that the void:

(a)

is at least one square foot in total area;

(b)

blows air from within the substrate;

(c)

consistently receives water during any rain event; or

(d)

potentially transmits groundwater.

(3)

Construction may only proceed after mitigation measures are reviewed and approved by the Watershed Protection Department.

Source: City Code Section 25-8-281; Ord. 031211-11; Ord. 031211-42; Ord. 20131017-046.