The Ohio Department of Transportation is expected to start construction of a retaining wall in January 2017 to stabilize the slope that supports State Route 315 between Jewett Road and the Powell city limits.
According to ODOT District 6 officials, the bank between the river and the State Route 315 is monitored on a biweekly basis. They said the river is moving toward the slope supporting State Route 315. In order to maintain the highway and prevent further damage, the slope must be stabilized.
ODOT has determined that the best method with the least impact to the natural scenic value of the river bank is to construct a “plug pile” wall. The wall is constructed by drilling holes into the bedrock then inserting steel beams into the holes of the rock and pouring concrete into the holes to fill in around the beams.
“The retaining wall work will stay out of the river, with most of the wall buried in the existing hillside,” said Nancy Burton, ODOT 6 public information officer.
“There will be some small amounts of rock placed at the outlets of several culverts that are being replaced with the project. The rock is placed to control erosion from the pipes. The erosion control includes the normal silt fence/seeding and a turbidity curtain.”
Only the concrete top of the wall will be visible to the public while the steel beams will remain hidden. By using a “plug pile” wall to stabilize the slope, the vegetation is preserved as much as possible. The method doesn’t require a causeway, disturbs less of the natural environment and results in a reduction of runoff into the Olentangy River.
Other options to stabilize the slope would have required excavation of the bank and removal of the natural vegetation along the slope.
“Many trees within the project location will be trimmed to allow for the retaining wall construction and utility pole relocation,” Burton said. “We have minimized the amount of trees cleared to be necessary for the work and have called for trimming of branches where possible, as opposed to a clear cut or full removal.”
Burton said some trees will be removed.
“We do not have an exact count until we meet with the contractor and review the plans together which is expected to happen within the next two weeks,” she said. “Seeding is included to restore disturbed areas and a limited number of small trees are included in the plans.”
According to ODOT, the daily traffic using the State Route 315 and State Route 750 intersection are 16,250 vehicles per day west of the intersection; 18,460 vehicles per day east of the intersection; 8,450 vehicles per day north of the intersection and 17,860 vehicles per day south of the intersection.
The construction plans include the closure of SR 315 both north and south of SR 750.
“We will close 315 north of 750 over the winter for 100 days and then close 315 south of 750 for 50 days over summer,” said Burton. “There will also be a 14-day closure this winter of 315 south of 750 to relocate power lines and perform clearing.”
Burton said she did not have the exact dates, but there will be prior notification of the closings. Construction is expected to be completed in October 2017.
D. Anthony Botkin may be reached at 740-413-0902 or on Twitter @dabotkin.