Disposition Summary

Approve the requested variance to reduce the minimum vertical curve K value from 25 to 23 on Vista View Lane at STA 116+25, based on the following evidence of hardship presented by the applicant.
a. This phase of the subdivision needs to be slightly higher than the prior phases to drain into the previously constructed detention basin properly. Reaching this higher elevation was done as quickly as possible along the proposed vertical alignment, resulting in a K value of 23 instead of 25.
b. Shallow rock is a unique condition to the property encountered on this proposed roadway from approximately Station 117+00 through the end of the alignment. The lowered K value request results from trying to get the vertical alignment above the rock layer as quickly as possible.
c. The granting of the variation will not be detrimental to public safety, health, or welfare because easements through the curves in question allow for adequate sight distance.

Approve the alternative design standards 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 8 conditions.

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Staff Recommendation

Approve the requested variance to reduce the minimum vertical curve K value from 25 to 23 on Vista View Lane at STA 116+25, based on the following evidence of hardship presented by the applicant.
a. This phase of the subdivision needs to be slightly higher than the prior phases to drain into the previously constructed detention basin properly. Reaching this higher elevation was done as quickly as possible along the proposed vertical alignment, resulting in a K value of 23 instead of 25.
b. Shallow rock is a unique condition to the property encountered on this proposed roadway from approximately Station 117+00 through the end of the alignment. The lowered K value request results from trying to get the vertical alignment above the rock layer as quickly as possible.
c. The granting of the variation will not be detrimental to public safety, health, or welfare because easements through the curves in question allow for adequate sight distance.

Approve the alternative design standards 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 8 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) Implementation of all recommended improvements identified in the Transportation Impact Study for Neals Landing, Unit III, prepared by Ajax Engineering, dated September 21, 2018, as revised and approved by the Knox County Department of Engineering and Public Works, Tennessee Department of Transportation (TDOT), Knoxville Department of Engineering, and Planning Commission staff.
4) Obtaining all applicable permits from TDOT for the required intersection improvements on Asheville Highway as identified in the Transportation Impact Study (See condition 3 above). The intersection improvements must be completed and bonded per the requirements of Knox County Engineering and Public Works before any additional house lots can be platted in the Neals Landing Subdivision.
5) Providing a 250 ft sight distance easement through the lots inside curves C1 and C5 per the requirements of Knox County Engineering and Public Works. Any driveways located within the sight distance easement must have a depth of 20 ft beyond the sight distance easement.
6) Meeting all applicable requirements of the Knox County Zoning Ordinance, including but not limited to, the intersection spacing requirements of Article 3, Section 3.51.02.C. of the Knox County Zoning Ordinance.
7) Meeting all applicable requirements of the Knox County Department of Engineering and Public Works.
8) 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 a redesign of a portion of the previously approved Neals Landing, Unit 3 (7-SD-20-C / 7-D-20-UR), which had 141 house lots, and 1 lot for an existing business. This proposal reconfigures Vista View Lane and Road A and the 40 lots that front them and adds one lot (lot 143) to Neals Landing Road where Vista View Lane was previously proposed to connect. If this proposal is approved, Neal Landing, Unit 3, will be approved for up to 142 house lots and one non-residential lot (lot 142).

According to the 2020 concept plan, Unit 3 is 25.1 acres. There is a final plat on the current agenda for a portion of Unit 3 that includes the non-residential lot (lot 142) at the corner of Neals Landing Road and Limelight Lane, which is 0.85 acres. The acreage dedicated to the non-residential use cannot be counted towards the allowed residential density. The gross density of Unit 3, excluding lot 142, is 5.85 du/ac.

VARIANCES AND ALTERNATIVE DESIGN STANDARDS
The reduction of the vertical curve from K=25 to K=23 is supported by staff because of the justification stated by the applicant. In addition, the proposed vertical curve meets the minimum standards of AASHTO for crest vertical curves on a 25 MPH street (K=12), and the minimum crest vertical needed to maintain 250 ft of continuous sight distance (K=20).

The reduction of the horizontal curve in Vista View Lane, from 250 ft to 127 ft, requires a 250 ft sight distance easement through lot 81. The driveway for lot 81 must be from Road A to eliminate the risk of vehicles backing into the road with limited visibility.

TRANSPORTATION IMPACT STUDY (TIS)
The transportation impact study submitted with the original Neals Landing, Unit 3 concept plan in 2018 (10-SC-18-C / 10-C-18-UR) concluded that the Asheville Highway eastbound left turn lane had to be extended due to this project. The turn lane extension must be completed or bonded before additional lots in Neals Landing, Unit 3, can be certified and recorded.