About 230 diseased trees are being removed throughout Hilliard during the second season of a five-year program to rid the city of trees infested by the emerald ash borer.
Emerald ash borers kill ash trees within three to five years of infestation, according to the Ohio Department of Agriculture.
Butch Seidle, Hilliard's public-services director, said prior to the proliferation of ash borer-infested trees, the city's budget allowed for the removal and replacement of 200 trees a year for any reason, including lightning strikes, those struck by vehicles or those with diseases.
The funding for the annual tree-replacement program was approximately $50,000 per year.
Seidle said 2012 was the first year in which nearly all of the 200 trees that were removed and replaced had been infested by the emerald ash borer.
To supplement the program budget, in 2013, Hilliard City Council set aside $200,000 in the capital-improvements budget for the removal and replacement of trees specifically infested by the emerald ash borer.
Seidle said it was estimated the city could remove and replace infested trees based on criteria that would be reviewed and subject to change each year in a five-year period.
"We did an assessment the first year and the result was a policy to remove all the infected trees that had a canopy loss of 80 percent or greater," he said. "We first looked at replacing those with a canopy loss of 50 percent, but it was too many trees (for the $200,000 budget), then we looked at 60 percent, and it was too many trees."
When city officials arrived at 80 percent, they determined the trees could be removed and replaced for $200,000, Seidle said.
It costs about $488 to remove and replace each tree, he said.
In 2012 and 2013, 556 emerald ash borer-infested trees were removed and 577 replacements were planted. This year, 227 trees are slated for removal and 454 for replacement.
The number of trees removed and replaced each year is not equal because some trees are replaced the year after they are removed, Seidle said.
Prior to the 227 infested trees slated for removal this year, the city had identified 1,047 ash trees infested by at least 5 percent in all quadrants of the city, Seidle said.
This year, all infested trees with a canopy loss of 70 percent are being replaced Seidle said.
"We've done a study this year but have not yet determined (a replacement policy for next year)," Seidle said. "The disease is not a linear progression.
"Some trees are at a 10 percent (canopy loss) one year and 50 the next; some are at 30 one year and 40 the next; some are unchanged. We've even seen a few recover somewhat. We don't know why."
The tree inventory is inspected each spring; replacement and removal takes place in the fall.
Residents are notified with a door hanger if a tree on their property is slated for removal and replacement, and the tree generally is marked in some fashion, Seidle said.
Apart from the emerald ash borer, the city also is treating an increasing number of diseased elm trees with a spray believed to be effective, Seidle said.
The city also identifies and removes trees with root systems that have caused residential sidewalks to buckle or separate.
"Maintenance of the sidewalk is the responsibility of the property owner, regardless of the cause for the disrepair," Seidle said.
However, in a good-faith effort to assist property owners whose sidewalks are raised or damaged by the root system of a tree in the public right of way, the city sets aside $50,000 a year to fund the replacement and removal of such trees.
If a sidewalk is raised one inch or more by a tree in the public right of way, the homeowner still is required to repair it but can apply for inclusion in the program, Seidle said.
The city would foot the bill for residents accepted into the program.
The cost to remove and replace a tree is about $488, plus about $300 to remove and replace 48 square feet of concrete -- or three slabs -- typically needed for sidewalk repairs.
"We use the $50,000 every year," Seidle said.
The city also compiles a waiting list for the following year, he said.
Those who choose to wait are liable for any accident that might occur prior to repairs, Seidle said.
The repairs must be made as the city requires. The city will not pay for pruning a root system or changing the level of the sidewalk, he said.
"We take out the tree and replace the sidewalk," said Seidle, adding that other solutions are generally temporary in nature.