New base for roadway is needed
Before beginning the construction process of expanding Rising Star Park, Platte City officials have determined they must alter their road improvement plan.
Rising Star Park will eventually be home to a splash pad and other amenities at the site of the former Rising Star Elementary School (previously known as Platte City Elementary School) at 1009 Second St., Platte City.
The reason to alter the road improvement plan is that during initial road construction it “became apparent that the underlying road base was in such poor condition that any new road surface would fail within three to five years of installation,” wrote City Administrator D.J. Gehrt in a staff report.
Before carrying out its expansion of Rising Star Park- a buildout over a 20-year period, Gehrt says the city must install a suitably constructed access road.
The original plan called for a two-inch asphalt cap on the existing access roads and parking areas. Once civil construction workers began construction, it was discovered the poor condition of the existing road would only cause the surface access road improvements to fail upon construction.
“Installing an additional two inch asphalt cap (the original civil construction scope of work) without constructing a road base will result in almost immediate failure of the new road surface and would require full road base installation at a later date,” wrote Gehrt.
An alternative option is to correct the road base and install a full-depth road with concrete ribbon curb. This plan requires the removal of a 11-inch deep section of existing road and sub-soil, installing six inches of compacted gravel base rock, installing three inches of compact asphalt base, installing two inches of asphalt surface material, and installing 1,894 feet of flat ribbon curb along the access road.
Additionally, the proposed road construction will address stormwater runoff along problematic areas.
The cost to overcome all the obstacles is an additional $121,066.
“The full depth road improvements will support the full park buildout over the next 20 years,” wrote Gehrt.
“It is far less expensive and intrusive to correct the road base during this initial construction phase than to spend $35,000 for a two inch base that will fail very quickly and will result in a situation that will still require full depth road reconstruction within one to three years after completion of the phase 1 work,” wrote Gehrt in a staff report.
Gehrt recommended the Park Committee forward the proposed $121,066 change order to the Board of Aldermen.
While acknowledging it’s a costly option, Gehrt warns “delaying base and subsurface improvements until later phases will impact use of Phase I improvements, will close portions of the park when the subsurface work is constructed in the future and will be more difficult and costly due to the need to deconflict future base and subsurface work with the completed Phase I improvements
City officials have a third option on the table. This option calls for the construction of a full depth road base minus the concrete ribbon curb. Gehrt pointed out in a staff report that the edges of the roadway will likely wear out without the 1,890 linear feet of concrete ribbon curb.