The stormwater plan for the proposed Gettysburg Station project drew criticism from Borough Engineer Chad Clabaugh at last night’s Gettysburg Stormwater Authority (GSWA) meeting. Clabaugh said the project will require significant redesign. “We’re nowhere close to having any approval,” he said.
Committee members weighed in during Harbaugh’s lengthy presentation, asking technical questions and debating maintenance, liability, and long-term functionality.
Clabaugh noted technical concerns with the applicant’s submission and said the site presents unusual challenges. The parcel is “a really crappy site for stormwater management,” he said. Clabaugh said there were 40 comments on the plan.
A central focus of the presentation was the developer’s proposed large underground rainwater holding facility, known as a Managed Release Concept (MRC). The system is designed to store stormwater in a subsurface chamber and then release it slowly through a ¾” opening. While the engineering calculations may meet state standards, Clabaugh argued the approach could prove problematic in practice.
Clabaugh said the impermeable design might be due to the site’s history as a former junkyard and cold storage facility. “A lot of stuff got buried over there,” he said.
Clabaugh explained that the proposal does include two manholes with 22 underground openings connected to the MRC discharge system. However, he cautioned that key portions of the system still would not be readily accessible without excavation for inspection and maintenance.
Because the design would leave a mostly-permanent pool of water underground, Clabaugh warned that sediment buildup and freezing could become long-term issues.
Another major problem, Clabaugh told the committee, involves the routing of pipes through the building footprint. “They have a pipe that goes through their parking garage structure that literally can’t work, because you would run a car into the concrete structure,” he said. Although the proposed pipe would be plastic, the borough generally tries to prevent pipes under buildings based on past failures elsewhere in town.
He noted that the Pennsylvania Department of Environmental Protection (DEP) is also involved in reviewing aspects of the plan and has recently tightened guidance on some of the stormwater credits the applicant is relying upon.
Summing up his view, Clabaugh described the proposal as “really overengineered,” but said he understood why the applicant pursued such a complex approach given the constraints of the site.
“These sites are really hard when you have existing impervious area like that and there’s nowhere around to take this water to. They’re trying to meet these standards, they have to come up with these fancy things to get the numbers to work; it’s really difficult.”
Clabaugh said borough staff intend to work cooperatively with the developer to explore simpler, more maintainable stormwater solutions before the project returns for formal consideration next month.
