§ 10-4.327. Topographic alterations.

All projects involving alteration of the contour, topography, use or vegetation cover of land, shall comply with the following minimum standards:

(1)

Sedimentation and erosion controls.

a.

Installation of controls. No clearing, grading, cutting, or filling shall commence until erosion and sedimentation control devices have been properly installed, in accordance with an approved plan, between the area to be disturbed and adjacent property, water bodies, watercourses (including inlets and culverts), and wetlands. Clearing and excavation required for installation of erosion and sedimentation control devices is allowed provided no activity occurs more than five feet from the location of control devices as specified in an approved plan.

b.

Methods of controls. Erosion shall be minimized and sediment retained on the site of development through the application of best management practices approved as part of the environmental management permit. Methods of control shall be suitable for site size, vegetative cover, soil type, slope, design features and proposed construction sequence and activities. Allowable methods include:

1.

Limiting the amount of clearing necessary.

2.

Staging clearing activities to minimize the length of time any area is left unstabilized and to minimize the total area cleared at any one time.

3.

Temporary gravel construction entrances.

4.

Straw bale barriers.

5.

Silt fences.

6.

Storm drain inlet protections.

7.

Temporary diversion dikes.

8.

Temporary sediment traps.

9.

Temporary sediment basins.

10.

Temporary stream crossings.

11.

Seeding so as to establish an appropriate vegetative ground cover.

12.

Sodding.

13.

Erosion control and seeding mats.

14.

Other suitable methods as approved by the county administrator or designee.

c.

Maintenance of controls. Once properly installed, erosion and sediment controls shall be maintained pursuant to section 10-4.210 until a permanent vegetative ground cover is established. Any site or portion thereof where work is not being performed as part of the current phase of development, and which remains cleared for over 30 days, shall be stabilized through the establishment of appropriate ground cover. All disturbed areas shall be permanently stabilized through the establishment of appropriate vegetative ground cover upon completion of development activities on the site.

(2)

Grade change limitations. It is the intent of this article to minimize alterations of the natural topography of land within the county.

a.

The type, intensity, and structural design of each proposed development project shall be consistent with and compatible with natural pre-development topography and characteristics of the proposed site.

b.

Alterations of natural topography shall not exceed the absolute minimum necessary to develop a site safely. Design criteria shall emphasize site designs that fit the topography to the best extent possible, not change the topography to fit the design. Any development proposed for a site shall be appropriate to the existing natural topographical characteristics of the site, while recognizing that minimal grade changes are essential to site development.

c.

The intent of protecting sloped areas of ten percent and greater is to maintain local topography, prevent erosion, protect water quality, and maintain existing vegetation. Manmade slopes shall not be regulated. Changes to grades that will adversely impact stormwater or ecological quality through long-term erosion shall be prohibited. This provision is not intended to preclude short-term impacts normally associated with development activity. Development in sloped areas of ten percent and greater shall be permitted as follows:

1.

Inside the urban service area:

(a)

Off-grade construction techniques shall be utilized to minimize clearing and topographic alteration, and shall provide (and clearly delineate on-site) specific clearing limits to restrict clearing and topographic alterations to the minimum area necessary for construction of the permitted facilities and reasonable construction access.

(b)

A minimum of 50 percent of significant (ten percent to 20 percent slope) grade areas must be left undisturbed if located adjacent to or within 100 feet of wetlands, waterbodies, watercourses, floodways, floodplains, karst features or special development zones. This requirement may be met by preserving 50 percent of each individual area or 50 percent of the total grade areas.

(c)

Severe grade areas (greater than 20 percent slope) shall remain undisturbed if located adjacent to or within 100 feet of wetlands, waterbodies, watercourses, floodways, floodplains, karst features or special development zones. Small areas (¼ acre or less) of severe grade areas located within significant grades may be regulated using the criteria for significant grades.

(d)

All significant and severe grades required to be undisturbed shall be preserved in their pre-development state by conservation easement.

(e)

The county administrator or designee may allow limited exemption from these grade change limitations for approved roadway projects, provided that the permit application related to such project includes: appropriate restrictive limits of areas as to clearing and topographic alteration; approved erosion and sediment control plans; and an evaluation of alternatives which support the allowance of an exemption.

(f)

Downtown overlay exception. Developments within the downtown overlay (section 10-282 of the city's land development code) are exempt from all severe grade regulations.

2.

Outside the urban service area:

(a)

Off-grade construction techniques shall be utilized to minimize clearing and topographic alteration, and shall provide (and clearly delineate on-site) specific clearing limits to restrict clearing and topographic alterations to the minimum area necessary for construction of the permitted facilities and reasonable construction access.

(b)

A minimum of 50 percent of significant (ten percent to 20 percent slope) grade areas must be left undisturbed or have an approved vegetation management plan and shall be placed so as to provide downhill buffers, protect forested areas, and buffer other conservation or preservation areas. This requirement may be met by preserving 50 percent of each individual area or 50 percent of the total grade areas.

(c)

Severe grade areas (greater than 20 percent slope) shall remain undisturbed. Small areas (¼ acre or less) of severe grade areas located within significant grades may be regulated using the criteria for significant grades.

(d)

All significant and severe grades required to be undisturbed shall be preserved in their pre-development state by conservation easement.

(e)

The county administrator or designee may allow limited exemption from these grade change limitations for approved roadway projects, provided that the permit application related to such project includes: appropriate restrictive limits of areas as to clearing and topographic alteration; approved erosion and sediment control plans; and an evaluation of alternatives which support the allowance of an exemption.

(3)

Flood zone grade change restrictions. The wetland protection provisions of article IV shall first be complied with prior to considering the provisions of this section. It is the intent of this subsection to allow selective alterations and redevelopment activities in those specific portions of a floodplain meeting the definition of altered floodplain, provided that the requirements of all other applicable portions of this article are met and that the applicant demonstrates in the permit application that a net improvement in the hydrologic function of the adjacent unaltered floodplain will result post-development.

a.

No fill or other alteration shall be made to the topography or vegetative cover in any floodplain. An exception to this provision is to allow up to a maximum of five percent disturbance to the unaltered floodplain located on-site, if the applicant demonstrates, to the satisfaction of the county administrator or designee, that there is no reasonable alternative. The following provisions apply to altered floodplains and to unaltered floodplains qualifying for the five percent disturbance:

1.

Minimum fill or alteration in a floodplain may be allowed for an approved road right-of-way, driveway, water management area, or septic tank, provided that all other applicable state and local standards are met and that the applicant demonstrates, to the satisfaction of the county administrator or designee, that there is no reasonable alternative to intruding into the floodplain and that the activities will not increase water stages (for the same event) on offsite properties, increase water stages onsite to an extent that this could cause degradation of onsite wetland vegetation, or increase flow velocities more than ten percent in unhardened stream beds adjacent to the area of the alteration.

For newly permitted roads within the floodplain under this subsection, which could be either public road rights-of-way or those that will be accepted by Leon County for public dedication, the applicant shall demonstrate that at full basin buildout, upstream backwater stages will be raised no more than one-half foot for a ten-year flood event, no more than one foot for a 100-year flood event, and no higher than one foot below the finished floor elevations of existing upstream occupied structures during a 100-year flood event. If flow velocities are increased to an extent that erosion of the streambed can result, the streambed shall be lined or energy dissipation devices shall be installed to lower flow velocities.

2.

For projects where placement of fill is allowed in a floodprone area or in the floodplain pursuant to subsection 1., compensating volume shall be provided. The compensating volume required shall be located so as to mitigate the ecological and hydrologic impacts of the fill.

3.

There shall be a prohibition against the placement of fill within FEMA designated floodways, except for the placement of piles, piers, or abutments as required for bridge construction and such construction shall comply with the provisions of subsection 1.

4.

Where fill is to be placed within a 100-year floodplain, as deemed necessary by the county administrator or designee based on technical criteria, compliance with the provisions of standards for flood hazard reduction, subsections 10-8.301(f)(1) through (6) shall be demonstrated.

b.

Fill for single-family home foundations located within the 100-year floodplain will be allowed as long as it is in full compliance with the technical policy as set forth by the county administrator or designee, "Policy Concerning the Placement of Fill in the Floodplain on Single-family Residential Lots" or its successor. This policy only applies to previously platted nonconforming lots where there is no reasonable alternative to the limited placement of foundation fill. This subsection or policy shall not be interpreted to facilitate in any way whatsoever the creation of new lots of record that would cause a single-family home to be constructed within the 100-year floodplain.

(Ord. No. 07-20, § 2, 7-10-07; Ord. No. 08-03, § 5, 1-29-08; Ord. No. 09-23, § 14, 7-14-09; Ord. No. 12-07, § 7, 5-8-12; Ord. No. 13-18, § 1, 9-24-13; Ord. No. 14-10, § 12, 6-10-14)