Kenton County Planning Commission’s Subdivision Regulation Committee has completed its review of more than 600 suggested revisions to its draft subdivision regulations for Kenton County. That review resulted in a consensus between competing interest groups in most cases. The single issue that prompted the most discussion was street design and subsurface drainage.
“Since the Kenton County Planning Commission adopted its first subdivision regulations in the late 1970’s, the provisions haven’t included any requirement for subsurface drainage except in limited locations,” said Scott Hiles, NKAPC’s director of infrastructure engineering. “Staff was directed this time to change that and add new requirements that would achieve better performing streets that have fewer pavement failures over time.”
The draft regulations developed by staff included those provisions.
After months of review and comments from four main interest groups—the Northern Kentucky Homebuilders Association, the Northern Kentucky Society of Professional Engineers, Henry Fischer of Fischer Homes, and the Kenton County Mayor’s Group—the committee directed staff to revise the draft to:
• limit concrete to crushed limestone aggregate to reduce D-cracking and surface deterioration;
• increase pavement and subgrade cross-slopes for better pavement drainage;
• increase the quality of expansion material at all expansion joints to increase their effectiveness and longevity;
• increase amounts of expansion material at driveways, on the outside of street curves, and the terminus of the street to reduce the effects of street creep;
• require edge drains under the curb where 51% of the adjoining lot drains toward the street and also in sag locations for increased subsurface drainage; and
• require a detailed pavement analysis performed by a geotechnical engineer for each project to determine any other pavement and drainage enhancements that should be utilized.
The noted requirement for edge drains is similar to the design proposal made by the engineers’ group. While committee members did not direct staff to require a full drainage blanket under all pavements as the Mayor’s Group recommended, they attempted to address the issue by requiring a detailed pavement analysis on every project.
“The committee agreed that a drainage blanket is needed in certain situations,” said Hiles. “But it also believed that requiring them everywhere as a minimum standard was overkill. In the end they determined that a geotechnical engineer should decide precisely where they were needed following the required pavement analysis. The geotechnical engineer could also require other improvements such as more edge drains or longitudinal drains.”
Staff is currently in the process of crafting the new street design standards established by the committee. When complete, the committee will distribute the new standards to the four interest groups in preparation for a roundtable meeting tentatively scheduled for February 28th. The goal will be to give these four groups the opportunity to discuss the design proposal and to provide the committee with additional feedback. After this meeting, the committee will give staff a final directive on what design proposals should be included in the draft regulations.
The final step will be to schedule the resulting draft to a public hearing before the full county planning commission membership. The plan is to hold that hearing and adopt the new regulations this spring.