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Staff Recommendation

Approve the development plan for one detached residential lot, subject to 6 conditions.

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1) Meeting all applicable requirements of the Knox County Health Department for the construction of a subsurface sewage disposal system.
2) Meeting all applicable requirements of the Knox County Zoning Ordinance.
3) Meeting all requirements of the Knox County Department of Engineering and Public Works.
4) If during permitting or construction, it is discovered that unforeseen off-site improvements within the right-of-way are necessary as caused by this development, the property owner will either enter into a memorandum of understanding (MOU) with the County for these improvements or reimburse the County for their direct expenses (if completed by County crews) to make corrections deemed necessary.
5) Submitting a geotechnical report for review and approval by Knox County Engineering and Public Works to determine if the closed contour on the plot plan is required to be shown on the final plat as a closed contour sinkhole with a 50-ft buffer as required by Section 3.06.B of the Subdivision Regulations. If any building construction is proposed within the 50-ft buffer area around the designated sinkholes/depressions (including the depression), a geotechnical report must be prepared by a registered engineer to determine soil stability, and that report must be submitted to the Knox County Department of Engineering and Public Works for consideration. Any construction in these areas is subject to County approval following a review of the report. Engineered footings must be designed for these areas. If the lot does not have a building site outside the 50-ft buffer, approval from Knox County will be required prior to final plat approval. The sinkholes/depressions and the 50-ft buffer shall be designated on the final plat, even if they are approved for filling.
6) If the closed contour sinkhole must be shown on the recorded plat, the property owner must submit a plat for review and approval by Planning staff and Knox County Engineering and Public Works and record the plat with the Knox County Register of Deeds. The plat must show the outer extent of the closed contour and list all plat notes required by Knox County Engineering and Public Works.

With the noted conditions, this plan meets the requirements for approval in the PR district and the criteria for a development plan.

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This request is to construct a detached residential house on this 4.3-acre property located in the River Island Plantation Subdivision. The subject property was approved on the concept plan as an amenity area for the subdivision (8-SG-01-C). However, the property owner and the homeowners association have agreed to allow the lot to be used for a residence and it will be included under the subdivision's covenants and restrictions (see Exhibits B and C).

Most of the subject site lies within the outer extent of a closed contour, which may indicate the presence of a sinkhole. The applicant submitted a geotechnical study limited to the area near the location of the proposed house, which concluded that the "site conditions are not indicative of active karst solutioning." Since the geotechnical study examined only a limited area, it does not conclusively rule out the possibility that this is a sinkhole. Therefore, the house must be located outside of the rim (highest elevation) of the closed contour, and if constructed within 50 ft of the rim, the house must have engineered footings. The site plat indicates that the rim of the closed contour is at the 879 contour; however, the highest spot elevation around the closed contour on KGIS is 879.8. The house location may have to be moved further to the south if its proposed location is determined to be within the closed contour's rim.

DEVELOPMENT PLAN ANALYSIS PER ARTICLE 6, SECTION 6.50.06 (APPROVAL OR DENIAL) In exercising its administrative judgment, the Planning Commission shall determine whether the proposed plan is in harmony with the general purpose and intent of the zoning ordinance and adopted plans.

1) ZONING ORDINANCE PR (Planned Residential) up to 2 du/ac:
A. Converting the subject parcel to a residential lot results in a gross density of 0.64 du/ac for the entire PR zone district, which is well below the maximum allowed density. The individual site will have a density of 0.23 du/ac.
B. The PR zone allows houses as a permitted use.
C. The proposed 20-ft front and 15-ft side setbacks are generally consistent with the surrounding neighborhood. The rear setback is unspecified, so it will be the 15-ft default setback for the PR zone per Article 5.13.09. The neighborhood's covenants and restrictions may require larger setbacks.
D. The house and accessory structures must remain outside the closed contour on the site, unless approved by Knox County Engineering and Public Works during permitting.

2) KNOX COUNTY COMPREHENSIVE PLAN - IMPLEMENTATION POLICIES
A. The proposed house lot is compatible with the other residences in the River Islands Plantation Subdivision, consistent with Implementation Policy 2, to ensure that development is sensitive to existing community character.

3) KNOX COUNTY COMPREHENSIVE PLAN - PLACE TYPE
A. The property is classified as the RL (Rural Living) place type. Single-family homes on a wide range of lot sizes are a primary use.

4) KNOXVILLE - FARRAGUT - KNOX COUNTY GROWTH POLICY PLAN
A. The property is located within the Rural Area on the Growth Plan Map. According to the Growth Policy Plan, the Knox County Zoning Ordinance and Zoning Map shall determine land uses permitted in the Rural Area. The rural designation shall not impede the right of a property owner to use or develop the property for a purpose permitted by that property's zoning. - The proposed house lot is consistent with the rural designation.