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.

More White Pines and Spruce Dying

The latest white pine fatality in the neighborhood is at the edge of my backyard and Potts Park. Across the street from my house is a dead spruce. The township arborist believes that the drought last summer, plus another drought this year in late June and July, may have stressed some of the local white pines and spruces beyond their limits.

Another arborist tells me that the herbicide Imprelis, mentioned in a previous post as a possible culprit, would only affect the more manicured areas where herbicides are more likely to be used. Spruce and white pine have been dying in many unmanicured areas, and he sees climate shift as a likely cause. White pines and spruce were introduced to Princeton from their more natural range to the north, suggesting they'd be the first to show stress from increasing heat and drought.

Though all urban trees eventually have to be removed, typically at a cost of $1000 or more, one can speculate that the weather extremes associated with climate change are making those costs come due earlier than they would otherwise.

This particular tree had a scar that surely didn't help.

Flood Alert--Basement Recall

Heavy rains in late August can cause major mischief in Princeton, with many people gone on vacation and a lot of basements left unwatched. This is a good time to recall someone who's out of town, and consider contacting them to ask if their basement is prone to flooding. Typically, the worst flooding happens during the last of a series of downpours, after the ground has already become saturated from previous rains.

For my part, as the last downpour was easing up at dusk, I headed out across flooded streets to the high school ecolab wetland, where past overwhelmings of the stormdrains had caused water on Walnut Street to flow under the back doorway into the performing arts center, ruining the stage floor. Since that fiasco, the school has sandbagged the doorway during heavy rains. But in late August, it's quite possible that the staff who know about the sandbagging procedure are on vacation.

 

The first evidence of heavy flooding was a green frog playing the role of refugee from its own wetland,

which was filled to the brim with water from nearby roofs, parking lots and streets. It's supposed to fill up like that; the design flaw is in the overflow, which sends extra water not out into the street but instead towards the school. The hallway of the performing arts center looked a little wet. I slogged home, called the borough police and asked them to have someone at the school check for flooding indoors.

Of course, it would be nice if product recalls could include flood-prone buildings and basements. Simply send them all back to the original builders for a redesigned version.

White Pines Turning Brown

When this neighbor's white pine started turning brown, I was secretly pleased. Growing to the south of my house, it had started to block out the sun's warmth in the winter. I had hoped the neighbor would take it down, to save the fig tree underneath it, and to give growing room to a nearby red oak. He had said he would, but didn't. Usually such an impasse continues for years, given the power of procrastination, but this year my wish came true in an unexpected way. The tree simply died.

Lest I think there be power in a wish, a recent email from former Princeton Environmental Commission member Grace Sinden implicated the herbicide Imprelis, manufactured by DuPont and approved last year by the EPA. It's used only by landscape professionals. Several other white pines around town have turned brown recently, though there's no definitive word on cause.

Harrison Street Raingarden in July

Another sight to be seen from Hamilton Avenue is the raingarden at Spruce Circle, just up from the intersection of Hamilton and Harrison Street. Type "raingarden" into the search box at the upper left of this blog and you'll find posts showing the raingarden in various seasons.

In July, the switchgrass (foreground) is fully grown, and the JoePyeWeed is in full flower (tall and purple).

A view uphill from the raingarden shows the long roof that feeds the garden during rains.

Here's a view from uphill looking down. Rain flows through the downspouts and out onto the grass, then down to the raingarden, where it collects and infiltrates into the ground over the next 24 hours or so, creating a nice underground reservoir of moisture to feed the roots of the wildflowers through droughts. Only in the most extreme droughts, such as the two-month long drought last year, does watering prove necessary.

Scattered through town, taking advantage of wet, sunny spots, raingardens like this one serve as lifelines for pollinators otherwise starved by the trees n' turf landscaping dictated by convention.

New Sprout Next To Princeton's "Mother Elm"

Keep riding up Hamilton Ave. and it starts changing names, which is one of the exciting things about living in Princeton. You think you're on one lazy street, when suddenly, unbeknownst to you, it has changed itself into another.

Hamilton Ave. is one of the most dynamic stretches of asphalt in this respect, perhaps in all the world, because it begins as Tyson Lane down in the lowlands of the east, then transforms itself in the blink of an eye into Littlebrook Road. Before you know it, it's changed again into Rollingmead Street, then settles into Hamilton Avenue for a good six blocks before whimsically becoming Wiggins Street. Subtle clues, which I have yet to discern, tell you if you're on a lane or a road or a street or an avenue.

Just before Wiggins is about to give up the ghost to become Paul Robeson Place, across from the public library, a glance into the cemetery will reveal a new American Elm growing next to the stump-shaped gravestone of the great "mother elm". Unlike many distinguished denizens of Princeton, the "mother elm" did not win a Nobel Prize, but it did earn an article in the NY Times at the time of its passing in 2005, telling of its glorious past and contributions to society. Those are some big shoes for the new tree to fill, but it appears unfazed.

Nut Sedge and Bindweed

My daughter says that what she likes about bike riding is that you're going just the right speed to see everything as you go by. A bike ride up Hamilton Ave. offered some fine displays of weeds for general edification. Most people would see in this photo a royal spread of turf meant to set off Westminster Conservatory to its best advantage. But what I noticed is the expanse of Nut Sedge spreading through the lower parts of the lawn. It's the light green in the photo, contrasting with the darker green of the turfgrass.

You likely have Nut Sedge growing in your garden. Like all sedges, it has a triangular stem. Most sedges are native and perennial. This one is non-native and an annual. It pulls out of the ground very easily, but is intimidating in its abundance. Either keep it well pulled, or suppress it with mulch, or, if you don't mind it taking over your garden, enjoy the attractive inflorescence it constructs on top of the stem.

As to what can be done about such an invasion of traditional turf, it's doing a good job of defining where Westminster could plant an expansive raingarden to feed the local pollinators and birds.

Further up Hamilton Ave., a fine display of Bindweed, the weedy member of the morning glory family, here seen crawling over boxwoods and a fence. Like Nut Sedge, it can be very hard to get rid of, but staying on top of the weeding will slowly starve the underground portion.

Struggling Trees Amidst the Splendor

Walking home from the Dinky through Princeton University's campus, my eye was drawn to two struggling trees amidst the splendor:

Why browned oak leaves in early summer?

Maybe this newly planted tree, with only a few green leaves left at the tips of branches, simply didn't get enough water, but another factor is its size. The bigger the tree being transplanted, the bigger the shock, not to mention the sticker shock. Hopefully it will recover and leaf out fully next spring.

Signs telling of recent pesticide application don't give one the warmest feeling,

but it's the only way to keep some of the university's remaining American elms alive (probably through injection into the trunk). This one isn't as graceful as some elms, but shows the distinctive vase-like shape that made elms such a wonderful street tree before Dutch Elm disease arrived on the continent.

Early Summer Wildflowers

A nice native combination this time of year is black-eyed susan in front of bottlebrush grass. These, along with cutleaf coneflower, tall meadow rue, wild senna and other local natives, I included in a miniature raingarden planting along the sidewalk at Whole Earth Center on Nassau Street.

Some white flowers to keep an eye out for are bottlebrush buckeye (in front of Mountain Lakes House),

buttonbush (along the edge of Carnegie Lake and the canal),

and Lizard's Tail (also found along the edge of Carnegie Lake).

On Tree Planting, And Believing in the Future

Having followed my kids to many a playground, I've noticed that parks often lack strategically placed shade trees. The result is burning hot play equipment in the summer. You'd think the planting of shade trees would be almost automatic in such situations, given that direct sun can otherwise render the equipment untouchable for hours at a stretch.

But even when I suggest trees be planted, I'm told that big trees are too expensive, and little trees take too long to grow.

This tree in Potts Park, then, is something of a contrary act. Donated by parents who wanted to celebrate their new son's arrival, it was planted with the conviction that time passes, trees grow, and the future will come.

Farming Princeton

The gradual conversion of Princeton's lawns to food production continues.

Community Park Elementary just got a new fence, paid for by the school district, to expand its school garden project and outdoor classroom. In the background, Dorothy Mullen, best known for her garden project at Riverside Elementary, is teaching a class.

Long in the making, the fence expansion provides more space for raised beds and a small orchard.

Meanwhile, passing by an Italian neighbor's sideyard farmlet on the other side of town, I noticed a strange-looking green and purple flower. He emerged from his productive jungle of vegetables and fruit trees to tell me it's a persimmon tree he started growing twenty five years ago. Over the years, he said, they've grown taller, and he's grown shorter.

Gravity Plus Rainwater= Backyard Waterfall

Garrison Keillor  made a disparaging remark about drainage during his show at McCarter Theater this past winter, but for many Princetonians, what seems like a mundane subject can raise considerable passion, particularly when the runoff is coming from the neighbor just up the hill, or results in basement flooding.

My advice is to give the water a good ride through the yard. Don't spurn it, or consign it to underground pipes. Water can be mischievous, but its obedience to gravity is absolute. Herded away from the foundation, it can flow on the surface to make attractive ephemeral streams and waterfalls, and feed plantings.

There's no reason, for instance, why water must fall from roof gutters in the obscure confines of a downspout. In this project, water emerges from a gutter (obscured by the shrub) in a small waterfall that is carried away from the house on a rockstrewn "streambed" underlain by black plastic.

The roof runoff flows down the rocks some 20 feet into a small raingarden (not in photo), where it collects and seeps into the ground, feeding nearby trees and any roots that reach it from the vegetable garden. In a deluge, the raingarden in turn overflows onto the lawn, where the water continues downhill as sheetflow. Whatever doesn't get absorbed eventually flows between the two neighboring houses down the slope and into a storm drain.

White On Green

 White must be a cheap and easy color for nature to produce, because there are so many white-flowered shrubs and trees this time of year. Among the natives, elderberry and silky dogwood have been blooming lately, having followed the Viburnums and flowering dogwoods that got the white theme going earlier in the spring.

Most thoroughly white is the Korean dogwood (Cornus kousa), which two weeks back was at its peak.

It blooms later than the native Cornus florida (florida as in florid), and this year was so prolific that the blooms completely obscured the green leaves underneath.

Planting the Extension With Something Other Than Grass

This spring I couldn't take it anymore. The sparse, beaten down patch of grass and weeds along the extension, that is. With hostas coming up in the backyard, as they have year after year, in places where I'd rather have something more interesting and dynamic, I decided to finally dig them out and test their florid toughness on the street extension. In the process, I'd be relieved of mowing a piece of lawn that grew more dandelions than grass.

I spaced the hostas every couple feet, and dug soil away from the edges of the curb and sidewalk. The edging accomplishes two things. It removes all the grass and weeds that might have grown up along the edge of the mulch, and also serves as a wall to keep the mulch from spilling out onto the street or sidewalk.

Edging, along with the dirt displaced by the hostas, also provided several wheelbarrows worth of dirt that I could use elsewhere. It's always good to be thinking about where you need some extra dirt. A garden is like a miniature town, with a certain amount of excavating going on here, filling going on over there. Throw in a miniature farm (vegetable garden), a nature preserve (wildflower bed), a landfill (compost heap) for kitchen scraps, and a yard can have its own economy.

These loads of dirt were headed for the intersection of my yard with the neighbor's driveway. The water runs off his driveway and would head straight for my house if I didn't make a berm that directs the water instead into a garden bed far from my foundation.

 While digging out the edges along the sidewalk, I noticed just how impervious is the soil in the extension, which explains why the grass was so ratty. You can see the thick red clay underlying sparse grass. Suddenly, the project took on a whole new civic and environmental dimension. All over town, the thin strips of grass between sidewalk and street likely have similarly poor, porosity-challenged soil that absorbs very little of the runoff from the sidewalk. Close-mown grass has very shallow roots that do little to improve the soils porosity. Changing to deep-rooted vegetation, such as these sacrificial hostas, combined with mulching to discourage weeds and provide cool, shady habitat for earthworms and other soil life, will over time change a bit of impervious ground into an absorber of rainwater, reducing by some small increment the flooding downstream.

Here's the completed planting, with hostas hopefully positioned so that they won't grow out over the sidewalk. Ideally, a good rain would have followed to wash the dirt off the sidewalk, but a bit of sweeping finished the job. If all goes well and the plants don't get too big, the area will need little or no attention for the rest of the year.

Update: One helpful step, not taken in this project, is to lay several thicknesses of newspaper or a single layer of overlapping cardboard down over the grass and weeds. This is primarily to prevent dandelions, curly dock and plantain from pushing up through the mulch. Unseen under a covering of woodchips or other mulch, the paper or cardboard decompose slowly, remaining intact long enough to exhaust the weeds of energy reserves.

Spring Cleaning in the Raingarden

 One of the easiest and most rewarding spring tasks is preparing a raingarden for a new season of growth. This raingarden was installed by Curtis Helm and me at Princeton borough's Senior Resource Center on Harrison Street. Water from the roofs is channeled into the garden, where it accumulates to several inches in the hollowed out area and then slowly seeps into the ground. Mosquitoes are not an issue because the water does not stand long enough for them to breed. A list of the plants, all adapted to wet soils, can be found in another post.

All that was needed was a pair of pruning shears, gloves, and a plastic grocery bag that was conveniently found amongst all the paper and plastic trash caught by the raingarden over the winter.  

 Though the spring cleaning of a raingarden is easy and rewarding, I nonetheless postponed it until the last minute. One more week and the new growth would have become tangled in last year's dead stalks.

First step was to cut the brown stems of joepyeweed, green bulrush and other native perennials.

 It's important to check the downspouts that conduct water to the garden,

one of which had lost its underlying stones and needed a little tightening of the joints.

Pulling the occasional weed like false strawberry (Duchesnia indica, also called Indian strawberry, because it is native to India),

and gill-over-the-ground ( Glechoma hederacea, also called creeping charlie, or ground ivy) is a piece of cake if the soil is still soft after recent rains. 

Garlic mustard is a common weed that will spread by seed if not pulled out before it flowers. I've heard it makes good pesto, but have never tried it out.

 All that was left was to pick up the trash and toss the stalks back in the woods. No need to burden the borough crews with yardwaste that can easily decompose unnoticed back near a fenceline.

Less than an hour and it was done. Now to figure out how to make a raingarden grow cake.