Sewickley residents in the Dickson Road area had plenty of concerns Tuesday night regarding the borough’s plans to fix a landslide-prone area in their neighborhood.
About a dozen residents attended a public meeting in council chambers to learn more about the sliding issue that encompasses Dickson Road and Miller and Farren streets, as well as the borough's commitment to fixing the problem before a potential slide shuts down the road or affects homes and properties.
A geotechnical report from Pittsburgh-based Garvin Boward Beitko Engineering, Inc. indicates the Dickson Road hillside area is located within an "ancient land-slide zone," meaning it has the potential to slide.
"That doesn't mean it's going to slide in two days, two years or 200 years," Borough Manager Kevin Flannery explained to residents.
Flannery was joined by engineers Joe Boward, of Garvin Boward Beitko, and Bob Firek of Lennon, Smith and Souleret, to discuss the report's findings. The report indicates that a road reconstruction would require stabilization of the hillside on both sides of the road, costing anywhere from $7 million to $15 million.
Flannery said those costs aren't feasible, but assured residents, many of whom have lived there for years, that the borough is looking at other solutions to what is essentially a road issue.
Boward said the best, most cost-effective option will be to construct retaining walls to stabilize two trouble spots-- the horseshoe bend on Dickson Road at Miller Street and a sliding section of Miller Street further up where the street has sunken down a bit.
Estimated costs on Miller Street only for the wall would range from $175,000 to $235,000, and for the horseshoe bend on Dickson Road from $45,000 to $70,000. Those figures don't include other associated costs, officials said.
Boward said the project involves drilling holes into stable bedrock and installing steel I beams, or soldier beams, and filling them with concrete.
Flannery said the goal is to construct the two retaining walls in 2014. In the meantime, he said the plan in 2013 will be to monitor water flow to see where the water is coming from and potentially reroute the flow. Officials will also monitor for movement in the hillside on a monthly basis.
Residents expressed concerns that a slide could affect their homes or the road. One resident said her home and others shook when fireworks were set off from the nearby cemetery for Light Up Night. They also wondered if the borough had a short-term plan should a slide occur before a fix.
Flannery said there is no such plan, but reassured residents they wouldn't have to move and that the borough would work to keep the road open.
"We're going to make the road passable as best we can. It's just that we cannot go in there and do any type of reconstruction," Flannery said.
Flannery and Boward said putting down asphalt or bringing heavy equipment, including firetrucks, onto the streets would only cause further damage.
Fire Chief Jeff Neff said the department already has an emergency plan in place for firetrucks responding to that area.
Boward said the slide isn't something that happens in one moment, rather it shifts and adjusts incrementally, and has been happening for thousands of years.
Sewickley is 10 years into an overall 30-year plan to fix every road in the borough. Earlier this year, Flannery said borough officials noticed water ponding at the top of the hill and requested engineering tests. Water is the single most deterrant to damaging the roads, he said.
Engineers drilled six test borings to look for groundwater and to get an idea of the strength and density of the soils. What they discovered, Boward said, were “Pittsburgh red beds,” a type of red soil or rock primarily composed of clay.
“If you find this material on your site, you immediately know you have a land-slide prone site, period,” Boward told residents.
Flannery agreed with a resident that weight limit signs should be placed on the roads. He said the borough will keep residents updated through email and urged anyone with questions and concerns in the meantime to contact the borough offices.