§ 19-411. Water Quality Protection Zone design standards.

A.

The Water Quality Protection Zone (WQPZ) for a stream system shall consist of a vegetated strip of land, preferably undisturbed and natural, extending along both sides of a stream and its adjacent wetlands, floodplains, or slopes. The width shall be adjusted to include contiguous sensitive areas, such as steep slopes, where development or disturbance may adversely affect water quality, streams, wetlands, or other water bodies.

B.

The required base width for all WQPZs shall be equal to:

1.

The greater of the following:

a.

One hundred (100) feet in width, measured from the top of the bank, on either side of the stream; or

b.

The designated Stream Planning Corridor as delineated on Exhibit 4-4 to the Storm Water Master Plan, dated October 2009, and accepted by City Council on November 10, 2009, and as available on the appropriate scale through the Public Works Department, or as indicated by the applicant's independent engineering analysis; or

c.

The FEMA floodplain; or

2.

An alternative width equal to twenty-five (25) feet in width, measured from the top of the bank, on either side of the stream when a reduction in nitrogen of at least seventy-five (75) percent and a reduction in phosphorus of at least fifty-eight (58) percent is achieved through the use of an engineered process that is certified by a licensed Professional Engineer. A development plan using an alternative width less than the SPC shall also document protection against flooding and bank erosion that would be anticipated during the one-percent-chance flood event in an given year assuming full build-out watershed conditions in those areas with forty (40) or more acres of drainage area in the Lake Thunderbird watershed. For the purpose of determining the applicable reduction in the base width of the buffer, the table below may be utilized to determine pollutant removal for a particular structural control, as long as such control is constructed in accordance with the specifications for said control contained in Wichita/Sedgwick County Stormwater Manual.

Table of Design Pollutant Removal Efficiencies for Stormwater Controls (%)
Structural Control	Total Suspended Solids	Total Phosphorus	Total Nitrogen	Metals
Stormwater Pond	80	55	30	50
Dry Extended Detention Pond	60	35	25	25
Enhanced Dry Swales	90	50	50	40
Grass Channel	50	25	20	30
Infiltration Trench	90	60	60	90
Soaking Trench	90	60	60	90
Vegetative Filter Strips	50	20	20	40
Surface Sand Filters	80	50	30	50

 

C.

For each portion of any twenty-five-foot segment of the buffer, as set forth in subsection 19-411(B), that has a slope over twenty (20) percent, twenty-five (25) feet shall be added to the width of the WQPZ. To determine the extent of steep slopes, a cross section of the topography every one hundred (100) feet shall be prepared and utilized by the applicant.

D.

In second-order streams with continuous water or in higher order streams, twenty-five (25) feet shall be added to the base width outlined in subsection 19-411(B) above.

E.

Drainage easements, of sufficient size to carry the runoff of a one-percent chance flood event from all drainage areas on the Plat greater than forty (40) acres within the WQPZ must be shown on dotted lines on the preliminary and final plats, along with a written legal description of any such easement, all certified by a licensed Professional Engineer. Such easement shall be granted to the City of Norman for the purpose of access for inspecting, repairing, and maintaining drainage channels.

F.

For all developments, particularly those containing some portion of the WQPZ, utilization of low impact development strategies are encouraged. For plats or Norman Rural Certificates of Survey that include portions of the WQPZ, the current Engineering Design Criteria may be modified when Low Impact Development strategies are utilized in accordance with City of Wichita/Sedgwick County Stormwater Manual.

G.

Water pollution hazards. The following land uses and/or activities are designated as potential water pollution hazards and must be set back from the top of the bank of any stream or waterbody by the distance indicated below:

1.

Storage of hazardous substances—(Three hundred (300) feet)

2.

Aboveground or underground petroleum storage facilities—(Three hundred (300) feet)

3.

Drainfields from onsite sewage disposal and treatment systems (i.e., septic systems)—(Two hundred (200) feet)

4.

Raised septic systems and raised mound septic systems—(Five hundred (500) feet)

5.

Solid waste landfills or junkyards—(Six hundred (600) feet)

6.

Subsurface discharges from a wastewater treatment plant—(Two hundred (200) feet)

7.

Land application of biosolids—(Two hundred (200) feet)

H.

WQPZ design restrictions. Except as required for initial construction, there shall be no clearing, grading, construction that disturbs vegetation on any portion of the WQPZ, the width of which is determined by subsection 19-411(B), (C) and (D) herein. Any development containing a WQPZ shall not be designed to contain within that zone any permanent structures or portions of septic systems, except for structural controls or other enhancing design features that will further the objectives of this ordinance.

I.

All applications for preliminary plats and Norman Rural Certificates of Survey that contain any portion of property within the WQPZ shall also submit a report outlining the Best Management Practices to be employed.

(Ord. No. 0-1011-52, § 4)