On the surface, Liberty Lands is a neighborhood oasis of spacious lawn and shade trees, community gardens and live performances and movies.
But it’s what is happening below the stage and water garden that could make the park a model for water conservation and storm water management projects around the city, and perhaps nation-wide.
Since June 2009, most of the rain that falls on this section of 3rd Street does not enter the city’s already overburdened single pipe sewer system. Instead, it flows through a natural filtration system of rocks and a specialized flower gardens, then into two underground cisterns that keep the water on site, to be used later to water the park’s non-food producing plants at will.
Recent water tests confirm what those who built and manage the system were always confident about: While not potable, the water is safe for irrigation use.
The results “are exactly what we thought they would be,” said Janet Finegar, park coordinator with Northern Liberties Neighbors Association, which originally built the park in the late 1990s.
It’s the levels of e-coli bacteria in the cistern water that make it unsuitable for drinking, said Sue Patterson, a long-time park volunteer who works in planning and research on the wastewater division of the Philadelphia Water Department and took on the responsibility of water quality monitoring. She recently received the first batch of results from Lancaster Laboratories in Lancaster, Pa.
Any system that diverts rain water for use or to prevent it from entering a sewer system is pretty cutting edge, particularly in this country, said Matt Ries, managing director of technical and educational programs at the Water Environment Federation, a not-for-profit association that provides technical education and training for water quality professionals. Ries said Philadelphia is an “early adopter” of “rainwater harvesting,” joining other cities including Seattle, Chicago, and the city most often named as a leader in this area, Portland, Oregon.
It’s about grabbing street runoff …
Using cisterns to collect and use street water makes the Liberty Lands project especially unusual, Ries said, and success here could encourage other cities to give it a try.
The Pennsylvania Horticultural Society, which partnered with NLNA and the city water department to build the water system, showed off Liberty Lands on a recent tour for visitors from other cities. The organization will continue to share what has been learned at Liberty Lands with other places, said David Elliott, a PHS landscape architect who was involved with the Liberty Lands project. “We are also working with the water department to have some kind of educational brochures made,” Elliott said. These would explain to park visitors what is not obvious from the surface.
“It is a really nice model,” said Joanne Dahme, a water department spokeswoman. It’s especially interesting that public run-off is being absorbed by private land, she said. Success at Liberty Lands could mean the spread of such systems, but more information will be needed first, Dahme said, including how much maintenance of the system costs over time.
“There are not a whole lot of models, so we have to be conservative moving forward,” she said.
It was the relative rarity of using street water that caused some hesitation during the 2007 planning phases of the park’s rain water project, Finegar said.
PHS approached NLNA about working with the society and the city water department to build a project that would demonstrate best practices in storm water management and would be paid for with state and federal grant money. The original idea, Finegar said, was to divert the rainwater from the street, sidewalk and park into a rain garden, where water would foster flowers and other plants while taking a minimum of two or three hours to slowly seep into the ground, rather than rushing into the sewer.
There’s good reason for keeping rainwater out of the sewers. Philadelphia and many other older cities have combined sewer systems, meaning that rain that hits impervious surfaces, like roads, roofs and parking lots, and then runs into sewer grates, joins with sewage in a single system of pipes. That means that even in the best situations, money and resources are spent treating rain water just like waste water, and bringing all of it up to drinking standards. Big storms cause more problems: The runoff overwhelms the sewer system, sometimes causing street flooding – Finegar says she used to see cars floating in her neighborhood – and sometimes causing some really awful stuff to back up into basements or flow, untreated, into the river.
…. and keeping it in place on site
So the Liberty Lands advocates were thrilled to do that much, but they wanted to take it further by saving the water to use on site.
Finegar explains how the first part of the system works. See the rest in the video below.
Partners from PHS and the city water department found the idea intriguing, but were worried about liability issues, Finegar said. Street water potentially comes in contact with oil, gasoline, antifreeze and other substances left behind by vehicles. And, because dogs are welcome at Liberty Lands, e-coli bacteria could be present in rainwater that fell on the park itself, and sitting in a cistern could give the bacteria time to multiply. Using this water in a popular public place seemed too risky for some people, Finegar said. People worried a health hazard would be created. “Street water was like a total unknown and it made everyone very nervous,” she said.
But because NLNA owned the park, the association could take on the risk, Finegar said – something that it would be much harder for a municipal entity to do.
Besides, the street water/cisterns concept was not unknown to everyone. And in another example of how the park seems to find experts it needs in the neighborhood, the McDonald brothers, owners of the environmentally conscious Onion Flats development company, were volunteering with the park project. Patrick McDonald, who is a master plumber, said that he had trademarked a natural filtration system to allow for site use of rainwater even before he and his brothers started Onion Flats. He’s been building projects that use rain water for about 15 years now, he said in a recent phone interview. “Now, every single one of our projects has rainwater reuse,” he said. While not everyone includes street and sidewalk water in the mix, some do, including Rag Flats in Fishtown
(The McDonalds wound up not only helping to design the system, but serving as the contractor that installed it. PHS had to use a bidding process, and NLNA was not involved. But much to the delight of Finegar and company, the lowest bid came from their pals.)
The legal hurdles
Still, for the sake of legal caution, NLNA created a separate entity to own the park, keeping the association’s money out of any potential litigation, Finegar said. The remaining obstacle was that the grants of about $170,000 could not be used for the part of the project that went beyond accepted best practices, she said.
So the grant money paid for re-contouring the land, which both funneled water to the rain garden and created amphitheater seating for movies and music, and it paid for a specialized storm grate that funnels water from the street and sidewalk into the park’s system, and through gabions – basically small rocks surrounded by larger rocks, held into a rectangular shape with wire – that spreads the water from the small inlet pipe out to an exposed stream. The stream, which flows only when it is raining, goes into a rain garden of plants that can tolerate a temporary influx of rain and the relatively dry conditions that exist there when no rain is present.
The storage and pump portion of the system had to be paid for with other money, Finegar said. Another local developer, Bart Blatstein (the man behind the Piazza at Schmidt’s, which is a short walk from the park) had planned on donating $25,000 to the park to create an emergency fund. NLNA asked if it could use the money for their water project instead.
With the liability and funding issues taken care of, Finegar said the NLNA’s partners became very excited to see what the project would yield.
How it works
The rain garden collects water in its 12 inches of soil, which then filters down to 12 inches of stone storage bed beneath the garden, which is lined with a type of plastic, Elliott said. From the storage bed, a pipe takes it into the cisterns, which can hold up to 6,000 gallons of water. It would take quite a storm or a series of storms to do it, but should the cisterns become full, the rain garden would pond up to four inches of water, then the water would flow into the sewer system.
The park volunteers were confident the system would work. But they did include a way to shut down the cistern portion, in case of a failure. Should that ever happen, the system could still be used as a retaining pond, holding the four inches of water before any goes into the sewer. In the system’s first year of operation, that has never happened. In fact, on a recent visit to the park during a persistant dry spell, the cisterns were dry and Finegar had to use city water to keep newly planted trees and flowers alive. The grass, she said, was on its own.
Finegar said the water system was a sort of science experiment, and “scientists have to be willing to fail.” That said, she’s thrilled that the tests came back the way they did.
Hydrocarbons were below the detection limit, as was chromium – a substance PWD’s Patterson was curious about because of the site’s former tannery use. Arsenic, which occurs naturally in many soils, was present, Patterson said, but not at a harmful level. And yes, the e-coli – suspected because some of the park’s fans are of the canine variety – was there, but the level was such that a person would “have to drink a gallon of it” to get sick, Finegar said.
Access to the cistern water is restricted by locks and the water is only used when someone from NLNA is there to make sure park users don’t take a drink, Finegar said. Finegar’s daughter plays in it sometimes, and she has had no problems.
Finegar continues a tour of the system.
Why it matters
Ries, from the Water Environment Federation, said that in many other parts of the world less water-rich than Philadelphia, people do not expect water used for irrigation and other non-consumption purposes to be safe for drinking. “We’ve been spoiled (in much of the United States) by the fact that we use potable water to wash our cars and our lawns.”
But bringing water up to drinking standards wastes environmental, financial and other resources, he said. People are starting to realize it, Ries said, even outside of places that face drought conditions. Signs are popping up on golf courses, for example, that say the irrigation water is not potable. The more this kind of thing happens, Ries said, the less people will assume that water coming out of a hose or irrigation system is safe to drink. And with that new mindset, the risk factor for using reclaimed water in public spaces will decrease dramatically.
Finegar said that without the grant money and a discounted price from the McDonalds, the water system would not have been financially possible for NLNA. Despite the free water the system provides Patterson said, it would have been much cheaper to pay Philadelphia’s water rates and use potable water for irrigation.
Elliott said while PHS hopes to be part of more projects that keep stormwater from inundating the sewers, it is likely that most of them would include systems that collect water on site and use it for rain gardens or in other ways allow it to slowly soak into the ground. Such systems are already in place at Cliveden Park in Germantown and Herron in South Philadelphia, he said. Both these parks received their water systems within the last two years.
“The concept of re-using water on site, that is an expensive endeavor requiring electric pumps, cisterns, and excavations,” he said. It may take a community group like NLNA that could get funding to build more cistern systems, he said.
And even with that, the water department’s Dahme said, caution would be needed, especially if a neighborhood group is taking on some of the responsibility. Not every community organization would have the capability of hiring a lab to do the testing, for example, she said.
The triple bottom line
Ries talks about the triple bottom line concept. Rainwater harvesting of any kind may or may not be the best for the financial bottom line of a business or homeowner, he said. But factor in the social and environmental benefits, and it makes all kinds of sense to a lot of people and, increasingly, governments.
In addition, he said, “there are lots of drivers that will eventually tip the scales. As the population grows, demand increases. And as energy costs increase, the cost of getting and treating water increases.” In some places, like Las Vegas, the costs have already begun to tip, he said.
Patrick McDonald, of Onion Flats, says the triple bottom line theory does not apply. “Don’t be fooled, it’s the all mighty buck,” he said. “Everybody and their mother can say ‘green, green, green,’ but the bottom line is cost engineering.”
That said, McDonald thinks systems akin to that at Liberty Lands – perhaps simpler, perhaps smaller, perhaps cheaper – are coming soon to a parking lot, business, or even single family home near you. His reasoning: The city’s new way of billing for stormwater management, which is being phased in starting this year, will charge customers based on the size of their properties, and the portion of the property that is covered in surface through which water does not penetrate. That means things like typical paved driveways, sidewalks and roofs. But users who can prove that their surfaces allow water penetration, or that water is collected from them and does not enter the sewer system will not be charged.
Collection systems add the benefit of free water. “The idea here is to collect the water when it’s free and clean it and use it for all kinds of things – hydrating plant life, flushing your toilets,” McDonald said.
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