On the Alewife, small flaws hint at things to come

Water has cut lazy curves into the side of the path north of Mass. Ave. View is south, with mass. Ave. in the background.

Water has cut lazy curves into the side of the path. View is south, with Mass. Ave. in the background.

Several months after its formal dedication, the Alewife Greenway is already gently aging.

With only one exception, the erosion and other signs of wear and tear are minor and do not interfere with the use or enjoyment of the path.

However, these small signs indicate what will need continual maintenance over time.

In particular, the path’s stone-dust surface is clearly eroding in places that were rebuilt or repaired as recently as August 31.

I walked the whole Greenway at the end of the year to see how things were doing, just before the snow. Come with me for a report.

One of the biggest repairs of the summer was to the path entrance here at Cottage Ave., where runoff had cut deep ruts in the entryway and was collecting in standing pools that persisted for a week or longer.

The repairs, for as long as they last, have resolved both problems. A heavy storm on December 28 dumped a lot of water on the path, as the below photo, taken an hour after the rains let up, suggests:

East and southeast from Cottage Ave. Note watter pooled on the path, and also that the drainage swale at left is completely inundated.

East and southeast from Cottage Ave. Note water pooled on the path, and also that the drainage swale at right is completely inundated. Click any photo for a closer look. Wooden curbing, center right, was added last fall.

There’s water on the path and the drainage swale at far left is full of water.

By the next day, however, the swale had drained and all of the standing water was gone, though the path was still soft in spots.

Water stands athwart the path after a storm. View is east from Cottage Ave.; that's Cambridge in the background.

Standing water athwart the path after a storm. View is east from Cottage Ave.; that’s Cambridge in the background.

That is how this material is supposed to work: it gets wet (and soft) but then drains and dries quickly. As my photos show, there were people walking on the path an hour after the storm ended.

Looking SE from the same spot. The drainage swale is inundated.

Southeast from the same spot. The drainage swale is flooded.

When completely dry, it’s quite firm; furthermore flaws that are introduced when wet and soft, like bicycle tracks or paw prints, get erased and smoothed out by subsequent softening storms.

The problems come when the path is not level or when storm-water runoff enters the path, sometimes with great force. Then the water both softens and moves the pavement, which after all is only stone dust.

Looking uphill (and west) to Boulevard Road, where runoff has dug a deep ditch in the entrance.

View uphill (and west) to Boulevard Rd.

The worst example of this on the path, now that the Cottage Ave entrance has been repaved, is a small entrance across  from the intersection of Boulevard Rd. and Lafayette St.

Here water drops a few feet from Boulevard Rd. to the path. The force of it has carved a deep channel through the stone dust and the underlying gravel foundation, which is thrust downhill.

The wash of stone dust and gravel extends in a broad semicircle over the opposite (eastern) edge of the path.

I think this entrance must somehow have been overlooked on August 31, when a work crew rolled fresh stone dust to make repairs or (in the case of Cottage Ave.) to complete work left undone all along the path.

Wetting and rolling activates binders in the stone dust, causing it to set fast. This procedure was not always followed in the first installation.

Runoff has washed a mixture of stone dust and gravel across the path onto the grassy bank to the east. View is south.

Runoff has washed a mixture of stone dust and gravel across the path onto the grassy bank to the east. View is south.

The Boulevard Rd. entrance is so badly worn that I do not believe it could have been included in these repairs. Consequently, it is a good place to see how fragile this material can be, and how things might start to look elsewhere in a year or so.

Back at Cottage Ave, things are holding together pretty well so far, but there are warning signs of erosion.

Footprints of Cottage Ave. runoff (view SSW from entrance path).

Footprints of Cottage Ave. runoff (view SSW from entrance path).

The entryway there has been under a pile of leaves for most of the fall, but even before leaf-fall there were small channels cut into the new surface.

I saw plenty of examples of this along every segment of the path, south (Minuteman Path to Mass. Ave.), central (Mass. Ave. to Broadway), and especially north (Broadway to Mystic River Parkway).

Except for Boulevard Rd., all parts of the path were in good enough shape for almost anyone to use, and the channels and flaws I found were essentially cosmetic. The question is, though, how long will they stay that way? Until then, these flaws are markers for future problems.

Other than that, the projects is of course weathering and aging in other ways.

There’s new graffiti on a bench south of Mass. Ave. The delightful painted Alewife continue to swim (the wrong way) on the sidewalk to connect the path segments, except on Broadway where the old sidewalk has been replaced.

Grass seed planted on banks and verges last fall have sprouted. And branches and whole trees continue to come down all along the path.

Windfalls smashed the new fence in three places. View is west from the path.

Windfalls smashed the new fence in three places. View is west from the path.

By far the most treefall-prone segment is the one near my house. You would think after two microbursts and a hurricane, not to mention extensive clearing of trees for this project, that most of the vulnerable wood should have been pruned away.

Nonetheless, trees and branches felled by Superstorm Sandy smashed the new fence in three places, and there is a small forest of tree limbs piled up on the path just north of the entrance at Cottage Ave.

If you have a wood stove, come and get this stuff, but bring a saw. Otherwise we will see how long it takes the DCR to clear things up and repair the fence.

The point is, life goes on. The path is built and now needs taking care of. How much, by whom, and how often, are details we can start to figure out in the new year.

Happy 2013 from the Word on the Street, a blog about Mass. Ave. and also, it turns out, sometimes about the Greenway path. Here’s the previous report in that series, and also the very first ca. July 2010. (Update: And the next.)

Cheers!

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5 comments so far

  1. dr2chase on

    How’s the section doing that was underwater in the flood?

    • Adam Auster on

      That is an awesome photo!

      It appears to be the view north from a point somewhere near Herbert St.

      Hard to say how it’s doing today, since the whole path is covered with snow. (Except for the paved Cambridge–Somerville side, which got plowed!)

      Despite the flooding, though, I think this area should wear pretty well. The path surface is wet and soft, but should firm right up again once dry. It’s actually an argument for this sort of self-repairing pavement, where it’s flat and there’s no runoff.

      Slanted ramps with runoff, like at Lafayette St., not so much.

  2. Douglass Davidoff on

    Adam, thanks for this report. The Boulevard Place connection needs attention. Perhaps a series of steps rather than a sloped path? The rises in the steps would hold back the erosion. Just my $0.02.

  3. Jeff Dearman on

    Thats why stone dust paths don’t work. Paved pathways are the best.

    • Adam Auster on

      @Jeff, they certainly don’t work as well as pavement in as many situations.

      By the way, the problematic areas have, predictably, continued to deteriorate. The stone dust is holding up well in the flat areas, though.


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