Devices may help ease flood pain
More than a century of flooding caused by overflows of Grafius Run may be coming to an end.
Over the past two years, the city has seen volumes of water from thunderstorms and deluges considered to occur once every 200 years, according to discussion Thursday night at the second of three public meetings on flood-mitigation of Grafius Run.
The meeting, held at St. Luke Lutheran Church at 1400 Market St., was attended by about a dozen people.
“Once the overflow of water gets passed here it’s too late,” said Jim Caldwell, project manager with Rettew, a firm hired by the city to find a solution to the street and property flooding and damage it leaves behind.
His finger touched a map showing Market and Elmira streets and showed how flood water can reach south to Hawthorne Avenue and flows west close to UPMC Susquehanna campus.
Caldwell was joined by Jeri McClune, chief engineer for water resources. They want the city to consider conceptual designs to control debris and increase the amount of water getting into the channel and not in basements.
“We have culverts … we want to minimize the overflows,” McClune said. “We want to maximize what goes into the culverts.”
A device shown was a self-cleaning trap with sharp teeth on it that can pull up as much as 3,000 pounds of debris like trash, logs and other materials that get swept downstream.
It was be installed near the intersection of Bloomingrove Road and Freedom Road.
It operates on limited horsepower and dumps the trash in the rear. It is small, about 15 feet, and doesn’t take much space.
A small wall is built upstream from the racks, enabling water to build up deep and increase pressure, meaning more flow into the culvert.
Excess trash can be collected by city Streets and Parks Department and hauled away.
Another option is larger and with two sides of trash racks operating with an open channel. The water flows through the open channel to an inlet leading into the culvert.
“These can be up to 400 feet long,” McClune said. However, the need for the flood mitigation on the run might require 200 feet of trash rack extension.
The trash racks would operate as a conveyor belt does at the sanitary authority treatment plant but with teeth and larger volume of trash collected. Riprap or other natural material would be on the bottom of the unnamed channel.
Additionally, an earth berm could be installed on Grafius Run to increase the capacity of water going into the culvert by as much as 50 percent, McClune said.
“It could triple water flow into the culvert,” he said.
Other solutions in the future may include building detention basins upstream in Loyalsock Township, where the headwaters of Grafius Run begin.
A question arose about whether Loyalsock Township would join with the city to seek funding sources for the equipment, design, installation and permitting requirements.
Such efforts are under way, and a meeting is planned with the township in a week, said Rebecca Haladay, city engineer.
A third meeting on Grafius Run flood mitigation solutions and final design proposals is planned for 7 p.m. Wednesday at the Trade and Transit Centre II.