It is a substantiated fact that areas of steep slopes, when developed into buildings and streets, present a significant threat of landslides or soil movement. This generally occurs on slopes exceeding fifteen (15) to twenty (20%) percent grades. (See: Landslides in the Nashville, Tennessee Area-Winter 1975, Robert A. Miller and John D. Wiethe, Tennessee Division of Geology, 1975) Oak Hill contains many such areas. Therefore, it is the policy of the City of Oak Hill to protect life and property by requiring special review procedures for construction on, or directly affecting, any steep slope where the area of the slope is one thousand (1,000) or more square feet and having a slope of fifteen percent (15%) or greater slopes. The applicant shall pay, as adopted by board of commissioners resolution, for review by the planning commission for steep slopes or in connection with the Radnor Lake Impact Ordinance. The following regulations shall apply:

(a)

Site plan required. No building permit shall be issued for construction on any area of fifteen (15%) percent or greater slopes until a site plan meeting the following requirements has been approved by the planning commission. Said site plan shall show:

(1)

The exact size, shape, and location of the lot, and the existing drainage pattern.

(2)

The proposed location of all buildings, driveways, drainage ways, and utilities.

(3)

Contours at vertical intervals of no more than five (5) feet taken from aerial photography or field survey.

(4)

The extent of natural tree cover and vegetation.

(5)

The location of any on-site soil absorption sewage disposal systems.

(6)

The type and location of erosion control methodology.

(7)

The exact area where any natural vegetation is proposed to be removed.

(8)

The size, type, and height of all buildings proposed to be constructed.

(9)

The location and extent of colluvial soil areas as determined by soil test borings.

(10)

The engineer's stamp that prepared the plan.

(11)

Certification as to the stability of the structures and slope and compliance with sound construction methods for areas with steep slopes and landslide problems by a registered geotechnical engineer. Said engineer shall also certify such features after completion of construction prior to issuance of the certificate of occupancy.

(12)

When the planning commission determines that additional information is required, an additional soils or geotechnical engineer may be employed to be funded by the developer. The planning commission may then require additional standards for development of the lot or tract if substantiated by the facts.

(b)

Development standards. The following standards shall be used as a guide in determining the suitability of the construction proposed for the particular site in question. The engineer's certification required in subsection 14-138(a) above shall address these standards:

(1)

Natural vegetation shall be preserved to the maximum extent possible. Existing vegetation on slopes fifteen (15%) percent or greater shall not be removed except as approved by the planning commission. The planning commission may require replacement of removed trees up to the caliper inches removed. Any grass areas shall be sodded.

(2)

Natural drainage ways and systems shall be maintained, except that surface water may be diverted around a house or slope area to a natural drain using acceptable construction techniques.

(3)

Development shall require a minimum of two (2) acres of land per parcel. The planning commission may require additional acreage when justified by the soil tests and/or slope of the site and limit development to a maximum of ten (10%) percent of the lot.

(4)

Off-road vehicles shall be prohibited from all such areas and may not be operated off streets and driveways.

(5)

Operations that increase loads, reduce slope support, and cause instability of the slope shall be prohibited to the maximum extent possible which will permit reasonable development of the site. These include filling, irrigation systems, accessory buildings, and on-site soil absorption sewage disposal systems.

(6)

Where sanitary sewers are not available, any on-site sewage disposal system shall be shown on the site plan and located to avoid slide prone areas. Said system shall be approved by the County Health Department prior to the planning commission's review taking into account these requirements.

(7)

Erosion control measures shall be employed to prevent all soil material from leaving the site. Additionally, soil from excavation on the site shall not be deposited as fill on a potential slide area. All aspects of the Metropolitan Nashville Storm Water Management Ordinance shall apply.

(8)

No construction, including for roads which would cut the toe of the slope shall be permitted, except as approved as a part of a soil stabilization plan submitted by a licensed geotechnical engineer on behalf of developer.

(Ord. No. 12-16, Jan. 2013; Ord. No. 2023-04, Exh. A, 2-27-2024)