Solarizing a Princeton High School Detention Basin

Earlier this fall, I was passing by Princeton High School on Walnut Street when I saw something I'd never seen before: 

a whole field covered with plastic. The field, next to the tennis courts and a parking lot, is actually a stormwater detention basin that the school wants to replant as native meadow. But before planting, they need to kill the existing turfgrass. 

I had contacted the schoolboard members on the Operations committee a number of times over the past year, promoting the meadow idea and encouraged them to contact a federal agency called Partners for Fish and Wildlife. Over the years, I had worked with Partners to convert, at no cost, a number of detention basins in town to native meadow--at Farmview Fields, Smoyer Park, Greenway Meadows, and even at the Princeton High School ecolab just down Walnut Street. 

Instead, the school hired at some expense an outside contractor to do the conversion. The plastic is probably a very plasticky attempt to avoid the use of herbicide. If you place clear plastic over grass, the heat from the sun gets trapped under the plastic. Like a greenhouse, or the earth's atmosphere, or the windows of a car parked in the summer sun, the clear plastic is transparent for light but opaque for heat. The sunlight travels through the plastic, hits the ground, turns into heat, and the plastic keeps the heat from escaping. Trapping solar heat to kill the grass is called solarization. I had accidentally done something similar when I laid a vinyl floormat on the grass next to the curb in the hopes someone else would find it useful. No one took it, and the grass under the mat was killed, leaving a brown spot for the rest of the summer.

This PHS environmental science teacher is one of several using this detention basin as well as the ecolab to teach about stormwater issues and habitats. 

Unfortunately, the plastic was installed late in the summer, as the sun's power was waning. When the plastic was removed this week, the results were less than impressive. A deep-rooted weed called plantain remains particularly abundant. 

It would be interesting to find out why herbicides were not used. The school may well have banned the use of herbicides when school is in session, but that doesn't preclude the use after hours or on weekends. Herbicides get a bad reputation for being heavily used to impose sterile lawns in suburbia, or on farms to eliminate every last weed, including milkweed. But they can also be used, in a targeted, minimalist, medicinal way, to kill invasive weeds that would otherwise be too difficult to control physically. We manage toxicity in our own bodies, taking only enough medicine to achieve a beneficial effect. Banning herbicides brings the comfort of absolutism, and makes people feel they're being green, all the while handicapping those who are actually doing the work to restore native diversity to the landscape. 

We'll see how the project goes. Not sure what happened to all of that plastic.

Working With Nature at the High School Ecolab Wetland

It wasn't easy to convince Tim to trim back the willow trees at the Princeton High School ecolab this past week. That's the detention basin that was only growing turf grass until the school gave permission for Tim's students and we community volunteers turn it into a very healthy native wetland. Maintenance isn't the right word for what we've done in the years since then, because though we "maintain" it, we also try to make it better and more diverse each year, while working to keep any one species from taking over. It's a kind of wild gardening.

Tim sees the willows as shade for the ponds (to keep them cool and discourage algae) and cover for the birds. I agreed, but also made the case that the rapidly expanding willows were making life harder for the 30 other native plant species meant to coexist there.

So we worked for a couple hours, trimming back the willows and doing general cleanup so that this detention basin can continue to thrive. Tim's turning the cut stems into a "corduroy" footpath.

Like any garden, this wild-looking wetland needs periodic rebalancing. The willows and the cattails--the two species most people associate with wet areas--are also the most aggressive and would over time displace the many shrubs, sedges and wildflowers that add to the diversity and beauty of the wetland.

The setting, with its elevated walkway and upscale fencing all around, is perfect for appreciating the tall wildflowers from above, as flying pollinators might. Even when the basin is performing its stormwater function, and fills completely with runoff during heavy storms, the plants bounce back after the water has drained out the next day.

Because the school sump pump that has serendipitously kept the wetland wet year-round was out of commission for awhile over the winter, there may need to be some restocking of crayfish and other aquatic species that have otherwise thrived from the beginning.

But that's all part of the ongoing balancing act, the periodic, strategic human interventions that are minor compared to the weekly mowing a lawn would have required. Our role is to make sure all the basic pieces of the puzzle--the sump pump, the plant and aquatic diversity--are present and in balance. Nature does the rest.

The Thriving Marsh at Princeton High School

All the finest native wetland wildflowers of the DR Canal, Carnegie Lake, Rogers Refuge and Mountain Lakes continue to thrive in that walled-in marvel of serendipity called the PHS Ecolab. The "PHS Ecolab" sounds like a ship, and it is in a way, an ark that survives flooding just fine but whose long term botanical prosperity and diverse portfolio of native species depends on the sweet, cool waters that flow from Princeton's version of Old Faithful--the sump pump that delivers doses of water from the high school basement every fifteen minutes or so, day in, day out. Yes, when the day is done, the property taxes paid, and Princeton's mood turns to romance without finance, many an evening walk begins with "Honey, lets go watch the sun set over the athletic fields, and see what's blooming in the high school wetland."

On this particular day, peering through the bars is a swamp rose, with a refreshing fragrance that cuts through the summer heat.

Green frogs and crayfish hide amongst the pickerel weed that continue blooming through the summer.

The blooms of lizard's tail don't last as long, but have a jazzier look. Impress your sweetheart by offhandedly pointing out that, unlike pickerel weed, Lizard's tail need not be in standing water to thrive.

See deeper meanings in the miracles a little basement water can work if allowed to see the light of day.

Note, with a knowing nod of the head that suggests great wisdom, that even metaphors for personal growth need tending. As in the story of Noah, there are points along the way where human intervention is necessary, where the natural energy must be steered, lest this highly naturalistic garden tip out of balance. Small interventions, really--countering the imperialistic tendencies of otherwise lovable cattail, pulling out any stiltweed or carpgrass that sneaks in. Maybe undercut the curly dock and plantain if they're getting too numerous on the elevated ground. Pull some of the goldenrod that's leaving no room for the cutleaf coneflower.

Or else, don't mention all the mechanics and let it all seem easy and natural. It is easy, except for a few hours a year, because working with nature rather than against it makes life easier in so many ways.

Wetland Wildflower Walks and Wednesday Workdays

The following activities, free and open to all, are sponsored by Friends of Princeton Open Space

WETLAND WILDFLOWER WALKS IN PRINCETON

Saturday, August 8, 10am : We'll meet at the Princeton High School Ecolab--a retention basin converted to a wetland that is now in full bloom--then walk to other rain or wetland gardens nearby. Meet at the ecolab wetland on Walnut Street, next to the HS performing arts center. All walking will be on pavement or lawn.

Sunday, August 16, 10 am: A walk along the canal towpath and nature trail loop to see a diverse floodplain plant community with an open canopy of oaks and rich understory that is reminiscent of fire-maintained savannas that would have been common in pre-colonial America. Meet at the towpath, just west of Harrison Street.

WEDNESDAY WORKDAYS AT MOUNTAIN LAKES, 10-12

Some folks have expressed interest in helping out at Mountain Lakes Preserve during the week. This month, I'll be leading volunteer sessions from 10-12 on Wednesday mornings. Rain date is Thursdays, same time. We'll only work when foliage is dry.

Our focus this summer is going after an exotic shrub called Asian Photinia, which has been invading Princeton's natural areas and Mountain Lakes in particular. We're cutting as much as we can now before the seeds ripen. These sessions are also a good opportunity for teenagers to get out and about.

Loppers, clippers, pruning saws, sturdy work shoes and gloves--all are useful. An r.s.v.p. is helpful for an estimate of numbers. Meet at Mountain Lakes House, up the driveway at 57 Mountain Ave.

Monarchs Bring Dance, Delight and Larger Meanings to a Backyard

These are the glory days for monarch watching, with the backyard packed with flowers--a veritable feast that we are grateful to provide.

Lovely as it is, the levitated landscape of pinks and yellows, reds and whites, gains a deeper meaning when a monarch arrives to animate the garden with its fanciful, danciful flight. Brilliance of color is matched by brilliance of movement, with glides and hairpin turns, sudden dips or dartings upward, gracing a garden's contours as if its flight were a form of affection. With an uncanny mix of power and whimsy, the monarch looks to know what it's looking for, as it approaches then darts away or doubles back, each minute of its flight a hundred instant decisions. What makes it land on one flower after approaching and rejecting so many others, seemingly the same, is a mystery.

This morning we saw four at once, two of which flew together, then collapsed upon the carport roof, there to mate for a minute while I ran to grab my camera. The one in front looks to be the female, with thicker veins and no little black spot on the wing.

This one here is a male, judging from the less prominent veins,

and those little black spots on either side of its abdomen.

The monarchs were especially drawn to the joe-pye-weed that with the summer's heat and rain have grown to ten feet high, like a mountain range of flowers.

Sometimes, when a monarch flew and flew around the garden, looking, looking, I thought it might be searching not for nectar but for a milkweed plant to lay its eggs on. Our swamp milkweed disappeared some years back, and this year my wife bought this kind, with orange and yellow flowers. Turns out to be tropical milkweed, native to Mexico but not here. It's pretty, easy for nurseries to grow, and rebounds quickly if ravenous monarch larva consume its leaves. It's also said to have some aspects, given the nature of its more tropical growth, that would make our northern native species of milkweed a better option,

like this butterflyweed that is flourishing in a neighbor's garden.

Most of Princeton's milkweed is common milkweed, which is less ornamental, spreads underground, and can be found in fields, along roadsides, and in this case growing at the nearby Princeton High School ecolab wetland. Other species include purple milkweed, a few of which grow at Herrontown Woods, and green milkweed, found years back in the meadows at Tusculum.

The dominant ideology of our day has deprived us of the satisfaction of contributing to something beyond ourselves. I grow more garden and less lawn because I love native plants, but the monarchs connect the garden to something much larger. Each March, starting out from their wintering home on just a few acres in the mountain forests of Mexico, the monarchs stretch themselves across all of eastern North America, ambassadors of beauty, as if to tell us that all our small efforts, spread across the land, are additive in and to nature, that we can contribute to something profound. May the monarch teach us how to find that satisfaction in other aspects of our lives as well.

Trenton Students and Science Mentors, Healing the Earth and Themselves

Last month, I found myself sitting at a table in the NJ State Museum, with a budding hyacinth for a centerpiece and a conference room full of high school students showing a budding interest in science. This trip to Trenton began with a surprise email that had arrived out of the blue two months prior:

"My Name is Tatyana and I am in a program called Science Mentors where teens are paired with a mentor and come up with a question that they will solve in order to enter their experiment and project into the Mercer Science and Engineering Science Fair. My mentor and I are very interested in the environmental factors of floods and while searching around the Internet we came upon a little information on water gardens. After visiting your blog we found out how knowledgable you are on this topic. Would you be able to meet with my mentor (Lisa Olson) and I in order to give us more information on water gardens and even be able to give us a tour of your water gardens so we could see them in person?"

So Tatyana came up to Princeton with her mentor for a tour of Princeton High School's ecolab wetland (fed by the school's "Old Faithful" sump pump) and the recreated stream corridor in my backyard. That gave her some ideas for two spots in Trenton, one being the empty lot next to her house, which gets lots of sun and could have some water directed to it from nearby roofs. 

The other is an empty field downtown with a river that runs through it. Well, actually, the river is a creek called Assunpink Creek, and it's been flowing underneath the field rather than through it, ever since the creek was buried to make room for urban development. That may change before too long, if plans put together by the city and the Army Corps of Engineers to daylight the creek are finally realized. 

We discussed what would be a good project having to do with raingardens. Identify what plants are growing in the field? Create a small raingarden there? I encouraged Tati and Lisa to consider inventorying the existing raingardens in Trenton, and see how they're doing. There's a great feeling of promise and achievement when a raingarden is planted, but birth is only the beginning. For a raingarden to thrive, it needs periodic infusions not only of rainwater but also of a love that expresses itself in the form of plant knowledge and periodically remembering to stop by to pull a few weeds. 

Science Mentors operates on a similar principal, that kids will thrive if given ongoing attention and caring. "If you have unconditional love, you can achieve anything, " says Maureen Quinn, the nonprofit's leader and soul. It was touching to see science so clearly paired with the healing power of love, and the awareness that one receives through giving. That is, after all, what drives a raingarden, and our lives.

Each student spoke in front of the group, describing their project.

You know, the world doesn't lack for sad stories. In the corridor leading to the museum's conference room, the story is very well told of the loss of the Carolina Parakeet,

and the passenger pigeon.

But those sad endings only make more moving the stories of thriving and renewal, stories that continue to be told through organizations like Science Mentors.

Nature's Upside Down Pecking Order

On June 19, the Princeton High School ecolab wetland was one of the stops on the Green Building and Garden Tour, organized by the Princeton Environmental Commission. The intention of this tour stop was to focus on how a retention basin can be converted into wetland habitat, but an airborne drama pulled our attention skywards.

A red-tailed hawk flew over from Westminster campus, chased by a pack of crows.

The scolding and intimidation continued for several minutes, as the crows took turns dive-bombing the hawk. The hawk kept an eye out, but seemed generally unconcerned. They'd all been through this before.

After the crows left, the hawk lay down and draped its wing over the edge of the roof, as if injured, or simply wishing to gather some warmth from the sun.

The crows returned, the hawk flew off, but one of the crows hung around long enough to in turn become the target of intimidation by a still smaller bird with white markings on it tail.

During summer break, it's feistiness rather than size that makes for a schoolyard bully.

Some Native White Flowers of June

Arrowood Viburnum (V. dentatum)

Virginia sweetspire (Itea virginica)

A new one in the yard, and on this blog: foxglove beardtongue (Penstemon digitalis)

Elderberry at the Princeton High School ecolab wetland

High School Ecolab Wetland--Early Summer Edition

Planted two years ago, the Princeton High School wetland is coming along. We've been nurturing the natives, pulling out the weeds or covering them with black plastic. Each year, a few new species get added. Here's what's blooming:

Pickerelweed blooms all summer long, and likes its feet in water.

Black-eyed Susans were bought from Pinelands Nursery and planted in drier areas of the wetland several years ago. It grows naturally in the meadows at Tusculum in Princeton.

Sweet Bergamot, rather than its red-flowered relative Beebalm, is native to the Princeton area.

Daisy Fleabane, a weedy but attractive native that shows up of its own accord.

Red Clover, though not native, is not invasive.

Joe Pye by the End of July

Judging from the corn fields around Princeton, the old adage "knee-high by the 4th of July" needs to be updated. Corn was at least head-high earlier in the month. The rhythm and rhyme can be applied to the classic mid-summer flowers of Princeton's floodplains, whether along the canal towpath or planted ten years ago on the higher ground at the Princeton High School ecolab wetland: JoePye by the End of July. That's Joe Pye Weed, which comes in several species, the most common around here seeming to be hollow-stemmed (not in the photo).

That's rose mallow hibiscus in the background of the first photo, thriving with its feet in water consistently supplied by the school's sump pump.

Wild senna is another classic mid-summer native flower, in the pea family. Planted in this case at the new botanical garden at Herrontown Woods, it has yet to be browsed by the deer. The white spires in the background are Culver's Root, a purchased native that I have yet to encounter growing naturally in NJ.

Another common mid-summer classic is cutleaf coneflower, not shown here, but popping out at the various places we've planted them in town.

Princeton High School Floods Again

Yesterday, with Hurricane Irene headed our way, I stopped by the Princeton High School to check on preparations for the coming deluge. This part of the school had stormwater seep under the doors a week ago, and was most emphatically flooded two years prior when Hurricane Bill paid a visit. I've heard from several sources that the bill for Hurricane Bill included a new stage floor for the high school's performing arts center, which had become warped by flooding damage. Even if insurance paid for the replacement, one has to wonder if the district school's insurance rates took a jump afterwards.

Here's how the flooding happens: The retention basin in the photo (a.k.a. "ecolab", which we have planted with native wetland species), is surrounded on three sides by the high school and receives runoff from the high school roofs and also from nearby parking lots. The basin in turn drains into the system of stormwater pipes underneath Walnut Street. If it rains long enough and hard enough, however, the street's underground stormdrain system becomes filled to the brim, water has nowhere to go, and the basin overflows. At that point, pipes no longer matter and surface flow dictates where floodwater goes. Since water flows downhill, the only way to get rid of the water is for it to flow out to Walnut Street and safely away from the building. Unfortunately, Walnut Street is higher than the high school doorway thresholds. In these heavy rains, Walnut Street floods and becomes a river, and stormwater actually flows towards the high school rather than away.

The highschool has responded to this by placing sandbags in front of all the doorways during heavy rains. These help, but when I stopped by at 1am this morning, after Irene's fury had begun to ease, the music room and hallway into the performing arts center showed signs of having again been flooded. (These photos were taken this morning, after stormwater had receded.)

Exasperated school staff were trying to pump water out of the school. The custodians had just finished prepping all the floors for the return of students, and now they would have to do it all over again. The cafeteria had flooded, and it looked like utility rooms in the basement were now under water.

One staff member tried to blame the vegetation in the retention basin, but all around him was evidence that the vegetation had played no role in the flooding whatsoever.

 

The drain, photographed this morning, showed no signs of blockage, which is no surprise given that, when the street storm drains become overwhelmed, the water reverses flow and heads in to the retention basin from the street, rather than out.

At 1am this morning, this whole area was a lake.

A curb cut meant to carry surface water away from the retention basin was instead carrying water towards it.

The only solution I see is to lower the curb on the other side of Walnut Street so that the mighty Walnut Street River can flow into the field owned by Westminster Conservatory.

This, in fact, is what some water was doing last night, but to an insufficient extent.

A pond formed in this field last night, next to the Westminster parking lot. Last year, the field was declared by Westminster's own consultants to be a wetland that could not be developed. Since the conservatory uses the highschool performing arts center for some of its performances, utilizing this field more effectively to prevent flooding of the high school seems to be a solution that would benefit all involved.






What needs to be made clear to decision-makers is that the native plantings in the retention basin have no impact on flooding, lest this ecologically vibrant and educational planting become the victim of an invasion of red herring.