I live in the suburbs west of Portland Oregon, 140 feet above sea level, on the side of a long-extinct, eroded, 1000-foot-tall volcanic ridge. The nearby houses and towering trees obscure the severe slope of my neighborhood. I once tried to laser-level my front yard, and discovered the south end was 3 feet lower than the north end.
I occupy the lowest of the eighteen houses on my block. The north end of my 900-foot-long block is about 60 feet higher than my yard at the south end. When it rains, everyone’s back yard drains downhill and through my back yard.
Welcome to Backyard Science’s (The) Daily Bucket. Here folks comment on what’s happening in the natural world around us. The clouds cloaking the moon, the squirrel destroying your bird feeder, the deer chewing on your pretty flowers, and the heavy snowfall that broke branches from your favorite tree are all fine topics. Please include your general area, and any related photos. We love photos!
We’d always wondered why the azalea and and variegated Pieris Japonica fared poorly along the north edge of our back yard. This fall I dug them up and potted them. Then I raked away the leaves where the plants had been, so I could see how that area drained. I knew it might be wet there, especially for the Pieris.
I also put down paving stones on the adjacent dirt path. My engineering firm Rube Goldberg, Homer Simpson & Associates had designed a path underdrain system that used up every scrap of waste pipe and rock that had been piled behind the shed. I wanted to see how it drained before proceeding further.
Then it snowed. The official figure was 12 inches. But I’m on the south slope and only had 6 inches in my yard. Then it rained six inches and melted the snow.
Many of the back yards above mine have 60-foot-high trees in the corners. Those huge trees suck up all the nutrients so little else can grow. Most of those back yards are bare hardpan, veined by surfaced tree roots, as pictured below. Storm water cannot soak into those firm surfaces. Instead it plummets downhill, towards my yard.
Decades of leaves and needles, trapped under my fence, did slow this creek down and diverted some water towards my neighbors to the east.
But over a day, thousands of gallons surged into my yard, right where that belegured azelea and Pieris once struggled to avoid drowning.
The good news was my french drain and piping under my newly paver-stoned path seemed to function well, discharging about 5 to 10 gallons a minute.
To my shock, 5-10 gallons/minute of outflow, about the flow of a strong garden hose, was not enough to drain my yard. Instead, water flowed in even faster, pooled, and backed up towards our house. I am thinking this might be the original stream bed of a creek that tumbled down this hillside decades ago.
I was surprised, but not worried. The paved areas would channel the storm water away from the house and down a paved path, that functioned like an open aqueduct.
Yet Mother Nature got the best of me once again, because snow and ice clogged the engineered aqueduct, forming a dam.
The storm water flows backed up, blocked by ice dams, and flowed uphill, carrying thousands of gallons of silty water into my largest pond. There’s an extra thousand turbid gallons pooled in the following picture, even while the pond drains from the upper right corner.
When I first set up this pond, if this had happened 10 years ago, I’d have been out there in 20 degree weather, sobbing, on my knees, spooning turbid water through a coffee filter to remove the silt.
These days?
“Heh,” I remarked to Salmon Woman,”Lots of extra nutrients in the pond today.”
“Hrumph,” she responded.
Between you and me, I like the flooded look. I like a bigger pond. That flooded path is shoreline frontage for my tool shed. We’ll move those ornamentals and plant some bog loving plants in the depressions.
And in summary, be glad that I wasn’t in charge of keeping the plutonium leachate pond from overflowing at the nuclear ��processing plant.
I’ve often reviewed storm water control plans for construction sites, and tried to utilize any common-sense regulations into my own DIY projects, for instance don’t dig up more area than you are going to work on that day. I even had two storm water collection ponds on site for this job. But I made the classic mistake; my storm water collection ponds were already full by the time the big storm started.
NOW IT’S YOUR TURN
What have you noted in your area or travels? As usual, please post your observations and general location in your comments. I’ll respond in between working on an endless list of flood control projects.
Be sure to peruse Meteor Blade’s valuable "Spotlight on Green News & Views,” every Saturday at 5pm Pacific Time and every Wednesday at 3:30 Pacific Time on the Daily Kos front page. Please recommend and comment in the diary.