On Saturday, May 10, 2014, a few heavy downpours made their way through North Granby. The result was a stream of sediment pouring down Peck Orchard Road from the Peck Orchard Knoll sand mining stockpile building site.
Not only did this wash across the road higher up, but water poured down to the foot of the road. When the drainage culvert further uphill got clogged with sand, it reached the lower culvert…
…which empties directly into Fox Brook.
The brook, which was running clear above the culvert, turned brown from the runoff coming through the culvert.
This picture is only a few hundred feet upstream from where Fox Brook discharges into Salmon Brook.
How did this happen? The evidence was there on Sunday. It all starts with the gigantic funnel created by the huge mounds of sand that have been bulldozed up and left exposed. These mountains were created weeks ago, and have stood untouched since then. Notice the pile on the right, which extends far above the original topography of the site. There’s another on the left, hidden behind a hill.
That part in the middle? That’s a “road” dug into the sand. Rain from these hills sheds down into this new artificial valley. Despite R. R. Hiltbrand’s presentation at the special permit hearing, wherein their engineer claimed that this sandy soil was incredibly quick-draining and it could absorb the runoff from a hundred-year storm, this summer thundershower obviously created damaging runoff.
Looking closer at that hillside, you can see the deep gullies created from erosion. It’s obvious that a lot of water ran down that hill, and that it wasn’t being absorbed by the sand.
When it hit the bottom of the sand ramp, it left a huge pile of silt on top of the traprock apron that Simscroft-Echo Farms installed.
That runoff was then funneled off to the side of the driveway… mostly. POK had a small pit in the sand here to catch sediment; it filled up in the previous storm. This time, it didn’t help.
The runoff went out and around the silt fence and hay bales that were supposed to contain it. It washed onto the “bituminous” driveway apron: chunks of loose asphalt material packed into a firm, but not solid surface. Why didn’t the silt fence work?
It was full. The design of this “erosion control measure” was laughably inadequate to cope with a spring thundershower; one can imagine how it would perform in a serious summer thunderstorm. It will take a lot more hay to stop a pile of naked sand this size from washing away.
Besides,a few wooden stakes pounded not very far into the ground are no match for hydraulic pressure. Once the stakes flop over, the fence does nothing to control runoff. However, it does present a serious hazard to traffic.
Past that silt fence, there’s evidence of a large, erosive water flow. Possibly it was enhanced by runoff from the hillside that has been stripped of trees but not yet stripped of topsoil.
The result was a veritable river delta stretching across Peck Orchard Road. On Saturday, this part of the road was a brown mass of silty runoff. On Sunday, it was a potentially deadly hazard to bicycle and motorcycle traffic.
Remember that bituminous driveway material? Here’s a whole bunch of it, several hundred feet down Peck Orchard Road. It may be more permeable than pavement, but it’s not permeable enough to stop this much water… and it doesn’t stay put.
Then we come to the first storm drain on the side of Peck Orchard Road.
If you’re looking for it, it’s right near the construction sign. (The one that isn’t reflective, and therefore can’t be seen well at night—which is why Connecticut DOT requires reflective signs for state contracts.)
You still can’t see it? That’s because it’s buried.
A few leaves and a whole lot of mud make for a clogged storm drain…
…but not before the whole pipe fills with sediment, and the outlet swale loses a few inches of depth.
Cleaning out that drainage pipe and runout is going to be a time-consuming, expensive job for Granby Public Works. I wonder if Granby taxpayers will be footing the bill?
Having filled up the first storm drain, the water kept flowing downhill, carrying silt with it.
Very little of this is from winter salt-and-sand spreading. Most of this is fresh silt.
Both sides of the road had torrents of water running down it. Here’s the erosion on the other side of the road. Fox Brook is about 25 feet to the right from this next shot.
By the time the water reached the second storm drain, it was still carrying substantial silt. It made a good start on clogging this drain, too.
You can still see the new layer of sediment in Fox Brook at the other end of that culvert.
But at least it’s not like there’s any environmental threat from this sand, is there?
I think that filling Salmon Brook’s tributaries with sand might have an effect on any juvenile salmon that might be present.
Since these photos were taken, Peck Orchard Knoll has dug out some, but not all, of the silt from behind their silt fence, and they’ve pounded those wooden stakes back into the ground. The road has been swept, but it still raises clouds of fine sand dust when people drive past. (The past few days haven’t been kind to the paint on cars traveling Peck Orchard Road!) Even so, if we get another fast-moving downpour like last Sunday, this will happen again. The same erosion controls are in place, and they are demonstrably inadequate.
And Granby still hasn’t gotten around to making it illegal to do this again.
