Engineers look to green infrastructure to alleviate flooding

RAVENA — When there is a substantial rain storm, areas in the village of Ravena can get flooded — in some areas the water can actually get a couple of feet deep.

Finding ways to alleviate that flooding, and removing or redirecting the water, can be a pricey proposition. The village of Ravena is looking at finding green solutions to the problem.

Green infrastructure can include adding trees, rain gardens, planter boxes, permeable pavements, bioretention areas and the like.

On Monday, Sept. 24, village and town officials and residents met with Crawford and Associates Engineering to discuss the firm’s findings and what can be done about the problem in a cost-effective way.

“We are here to present our study of green infrastructure opportunities for the village of Ravena,” said General Manager Donna Verna from Crawford and Associates Engineering and Land Surveying.

Verna and senior engineer Michelle Mormile presented possible options the village could pursue, as well as a grant application that has already been submitted on the village’s behalf for a specific project.

The goal was to look at possible ways to “manage stormwater in the village and relieve pressure on the undersized stormwater system and reduce occurrence of stormwater entering the village’s sanitary system,” Verna said.

The firm applied in December 2017 for a grant to the Hudson River Estuary Grant Program to pay for a feasibility study, and that grant was awarded. Over the winter, work got underway to analyze possible green infrastructure solutions to the village’s flooding problems. In July of this year, that feasibility study was completed by Crawford and Associates, in particular looking at flooding and possible solutions with regard to the municipal parking lot on Main Street.

Several homeowners with properties near that parking lot — across the street from the post office — also attended the meeting to discuss the flooding problems they experience at their homes.

The firm also looked at several other potential sites for green infrastructure, including five village-owned properties — the Ravena Village Hall on Main Street, the Main Street parking lot, Ravena Senior Projects and the Rescue Squad, the parking lot on Central Avenue, and portions of Main Street.

Four non-village-owned properties were also studied — Coeymans Town Hall, Faith Plaza, Pieter B. Coeymans Elementary School, and the parking lot at St. Patrick’s Church on Main Street.

Verna said they started with an “initial desktop site review” by considering a soil survey, wetlands, flood plains, hotspots, and potential green infrastructure practices. Then they went to each site to see “what would be practical and make sense,” she said.

Once that was done, they developed cost estimates for each possible project. Verna said the numbers came out seemingly high, but there are reasons for that.

“I learned that cost varies considerably for green infrastructure because of things like site conditions, space limitations, existing utilities, but one of the biggest factors is aesthetics,” Verna said. “If you have ever had landscaping done, it can get expensive pretty quickly. In some areas the aesthetic doesn’t matter, but in others the aesthetics come into play a bit more.”

Verna said that while costs for green infrastructure can be high, there are other factors to consider which can be difficult to quantify.

“There is additional value that green infrastructure can bring to a community,” she said. “It improves community livability, community aesthetics, increases recreational opportunity, reduces noise pollution, improves community cohesion.”

“If things are compared on a dollar-to-dollar basis, green infrastructure is going to look more expensive,” Verna said. “For that reason, many communities just go with gray [infrastructure] because it is known and it’s cheaper. But there are other benefits that are harder to quantify but also may be considered.”

There are ways to cut down on costs, though, such as putting in green infrastructure when another project is already underway or being planned.

“For instance, if you are going to redo sidewalks, that would be the time to look at putting in strips of green or a rain garden,” she said. “It would be more cost effective to do it that way than to put in the sidewalk and then put in green space later.”

You can also use economies of scale to cut down on costs.

The grant that the village is being considered for would pay up to 90 percent of the cost of the Main Street parking lot project and would replace the rear end of the lot, which is essentially unused right now, with green space. That green space would presumably absorb stormwater which currently just collects on the paved areas.

The village would be responsible for at least 10 percent of the cost of the project, which would be paid for through in-kind services, with village employees doing much of the labor to cover the village’s portion.

The cost of the Main Street parking lot project is estimated to be roughly $418,800, with the village covering at least 10 percent of that cost, possibly through in-kind services.

At the other sites that were considered in the feasibility study, there are a number of green options the village can consider, including adding porous pavement (for example, in parking lots), bioretention areas, rain barrels and stream restoration, Mormile said.

The ultimate goal is to add more green space to the community that can better absorb stormwater, in contrast with nonporous pavement.

In some areas of the village, homes have been damaged by flood waters, especially at properties near the Main Street parking lot. In some cases, the flooding can be downright dangerous.

“You don’t want to be there [when there is flooding off Main Street]. You could die there,” Ravena Deputy Mayor Bill Bailey said. “In a really heavy, heavy rain, you do not want to be in the back of that building because you can be whipped right off your feet.”

One homeowner said the water can get as high as half the height of her garage.

Mormile said some of those “storm events” are extreme, and this project can only resolve the problem to a degree.

“Green infrastructure is not meant to collect water in extreme storm events. This is for one-inch storm events,” Mormile said.

Village Foreman Henry Traver said green infrastructure could still prove valuable by slowing down floodwaters.

“You still may have flooding, but you may only have 15 minutes of flooding instead of two hours before it drains out. It won’t stop it, but it will slow it down so hopefully we can get manhole covers off and slow it down even more,” Traver said.