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Looking for truth on the ground: PSU Harrisburg students find clues to how stormwater system works

By Dan Miller

danmiller@pressandjournal.com

717-944-4628
Posted 11/29/17

Penn State Harrisburg students wearing yellow vests have been out “groundtruthing” all over Middletown and Lower Swatara Township.

Translated from civil engineer-speak, the students …

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Looking for truth on the ground: PSU Harrisburg students find clues to how stormwater system works

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Penn State Harrisburg students wearing yellow vests have been out “groundtruthing” all over Middletown and Lower Swatara Township.

Translated from civil engineer-speak, the students are in the field to see if the stormwater system that exists in these two municipalities is actually working the way it is supposed to.

The research is for a study that the Penn State Harrisburg students are doing of the stormwater system for the borough of Middletown.

The goal is to come up with recommendations that can help reduce the amount of flooding that occurs when the borough is hit with a significant rain event, such as on July 23 of this year when almost 5 inches of rain fell in one hour.

You don’t have to be standing in the middle of a torrential downpour to know if a stormwater system is functioning properly.

Rain and stormwater leave all kinds of forensic evidence — much of which is not obvious unless you know what to look for.

For example, a rust-colored trail shows how stormwater flows in the parking lot behind the Campus Heights student housing complex along Route 230 in Middletown.

Water runs downhill west to east, and is supposed to flow into the stormwater drains in the parking lot.

But students Sarah Ryan and Huzeifa Amiji found a drain sitting too high in the ground above the macadam. So most of the water that should be going into the drain is going around it.

Another sign that water isn’t going into the drain is that the bottom of the drain is clean, with little evidence of sediment and debris, said Ryan, who is a graduate student. Amiji is a senior.

Water going around — not in — one stormwater drain doesn’t by itself account for the flooding that was made manifest on July 23.

It’s just one small sign of how the system is performing below its intended capacity.

Something else that caught the eyes of the students was seeing stormwater drains in the grass behind Campus Heights.

You normally don’t need stormwater drains in the grass. The grass itself is supposed to help drain the stormwater.

But this land was part of the former Olmsted Air Force Base. Over time, the grass was probably “compacted” to where it became like an impervious surface, more like macadam than grass, Ryan said. When Campus Heights was built, the developers put stormwater drains in the grass to compensate for that.

The way land was used in the past is a factor in how well the land drains stormwater today, Ryan noted.

Examples like these also show that while the principle behind a stormwater system — water flows downhill — is simple, the system itself can be enormously complex, Ryan said.

Maybe that’s why a typical stormwater system study done by a consulting engineering firm can cost up to $50,000.

The Penn State Harrisburg students are doing the study for the borough for free.

The students are constrained by certain realities. But they hope to make a difference.

“At the end of the day, Middletown is at the bottom of the Swatara watershed,” Ryan said. “That is something that (Middletown) is always going to have to deal with.”

“But can we implement upstream solutions to help mitigate the impact of that? Can we slow down the water and time it so that it is not all coming down to the bottom of the water shed at one time? We’re really just trying to find what’s happening for real, what’s actually happening with the water in the system, and then look at how can we make some adjustments to help minimize some of those impacts.”

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