Disposition Summary

Approve the alternative design standard based on the justification provided by the applicant and recommendations of the Knox County Department of Engineering and Public Works.

Approve the Concept Plan subject to 13 conditions.

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Staff Recommendation

Approve the alternative design standard based on the justification provided by the applicant and recommendations of the Knox County Department of Engineering and Public Works.

Approve the Concept Plan subject to 13 conditions.

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1) Connection to sanitary sewer and meeting other relevant utility provider requirements.
2) Provision of street names consistent with the Uniform Street Naming and Addressing System within Knox County (County Ord. 91-1-102).
3) Providing a sight distance easement through the horizontal curve radius less than 250 ft and, if necessary, through lots 66 and 67 to maintain 250 ft of intersection sight distance looking west on Shadow Branch Lane at the southern intersection of Road 'B', per the requirements of Knox County Engineering and Public Works during the design plan phase. Any driveways that cannot be located outside the sight distance easement must have a 20 ft depth outside the sight distance easement.
4) Providing a 50-ft wide right-of-way stub-out from Shadow Branch Lane to the property to the west (parcel 021 04202). The stub-out shall be provided on the final plat and identified for future connection. The location of the stub-out shall be reviewed and approved by Knox County Engineering and Public Works during the design plan phase.
5) Installing the curbing and asphalt road surface through the intersection radii referenced in condition #4 and installing notification of future street connection as required by Section 3.04.C.2.d. of the Knoxville-Knox County Subdivision Regulations.
6) Submitting a geotechnical report for review and approval by Knox County Engineering and Public Works during the design plan phase to determine if any areas shown as closed contour sinkholes on the concept plan are 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. If any building construction proposed within the 50 ft buffer area around the designated sinkholes/depressions (including the depressions), 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 approval by the County following a review of the report. Engineered footings must be designed for these areas. For those lots that do not have a building site outside of the 50 ft buffer, approval by Knox County will be required prior to final plat approval. The sinkholes/depressions and 50 ft buffer shall be designated on the final plat even if they are approved to be filled.
7) If the approved geotechnical report determines that a closed contour identified by Knox County Engineering and Public Works is not a sinkhole, the certification to be provided by Knox County Engineering and Public Works must be placed on the final plat and sealed by the applicant's engineer.
8) Labeling the open spaces between lots 96 and 97 and south of lots 1-9 as common areas on the final plat.
9) Implementing the recommendations of the Whisper Ridge Subdivision - Phase 2 Transportation Impact Analysis (TIA) (Ardurra, 9/17/224) as required by Knox County Engineering and Public Works during the design plan phase (see Exhibit B). The design of the recommended traffic calming will be determined during the design plan phase with review and approval by Knox County Engineering and Public Works.
10) If during design plan approval or construction of the development, it is discovered that unforeseen off-site improvements within the right-of-way are necessary, the developer 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.
11) Meeting all applicable requirements of the Knox County Zoning Ordinance.
12) Meeting all applicable requirements of the Knox County Department of Engineering and Public Works.
13) Before certification of the final plat for the subdivision, establish a property owners association or other legal entity responsible for maintaining common facilities, such as common areas, amenities, private roads, and/or stormwater drainage systems.

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This proposal is Phase 2 of the Whisper Ridge Subdivision, which includes 102 detached residential lots on 34.26 acres at a density of 2.98 du/ac. Shadow Branch Lane will be extended onto the site from the existing subdivision.

BACKGROUND
The property was rezoned from A (Agricultural) to PR (Planned Residential) 1-3 du/ac in February 2005 (1-U-05-RZ). The Whisper Ridge Subdivision was approved for 119 lots over the entire 54 acres. Phase 1 was platted with 57 lots. However, 8 of the lots were never built and are being incorporated into Phase 2, and two other lots were combined with adjacent properties. As a result, Phase 1 has 47 lots on approximately 20.3 acres (2.3 du/ac). This proposal for 102 lots is an increase from the 70 lots originally proposed in the area of Phase 2. The typical lot width in Phase 1 is 90 ft, and in Phase 2, it is 55 ft.

TRANSPORTATION IMPACT STUDY (TIS)
The TIS studied the impact of the additional traffic on the intersection of Whisper Ridge Lane and Maloneyville Road, as well as the design of the proposed internal streets. The conclusions of the study are: 1) that turn lanes on Whisper Ridge Lane and Maloneyville Road are not warranted, and 2) that the straight stretches of roadway in the new internal streets can encourage higher vehicle speeds. The study recommends that traffic calming measures, such as speed humps and speed tables, be coordinated with Knox County Engineering and Public Works and for a certified land surveyor to verify that Maloneyville Road has adequate sight distance at the existing subdivision entrance. The minimum sight distance required is 300 ft, and the traffic engineer estimated the sight distance to be 465 ft looking right and 1,045 ft looking left.

ALTERNATIVE DESIGN STANDARDS
The applicant requests to reduce the minimum horizontal curve radius from 250 to 200 ft in the northern portion of Road 'B'. The reduced radius is needed because of the property's narrowness and to allow for a looped road system. A sight distance easement is required on the inside of the curve. In 2005, the subdivision was approved with two long cul-de-sac roads. The subdivision regulations recommend an interconnected street system when feasible.