Camp Meeker Beat by Tom Austin - April 2018
April already? And I was just getting used to winter. Time flies like an arrow. If you can’t fly like an arrow, you’ll probably need to drive. And if you drive, watch out for potholes. You’ve probably noticed some new ones after the recent storms. How is it that potholes form so fast and get so deep? It’s not as quick as it looks. Like tomato plants or an angry outburst, the process has been going on for weeks before the bloom. Water seeps into the roadbed through cracks in the asphalt, then spends time down there eroding the material that supports what you think of as the road (that asphalt thing), then finally washes enough of it away that nothing supports the asphalt, and it cracks. And lo, there is your pothole.
Why am I talking about potholes? Last month I started talking about roadwork and ran out of space. Now I have space. I will start with the burning question? When, oh when, is Bohemian Highway going to get fixed? One wag in particular, the one making the humorous graffiti on the bumpy parts of the road going up the hill to Occidental and down the hill to Monte Rio, particularly wants to know. Anyone who navigates the moguls in those spots wants to know: Bohemian Highway is less than smooth sailing these days.
According to the Sonoma County “Pavement Preservation” web page (just google those four words and you’ll find it), we are on the docket for some time in 2018 or 2019. The original plan was 2017, but there was such extensive damage (and, apparently, required ADA compliance sidewalk stuff in Occidental) across the county from the storms last winter that we got pushed back.
Well, gee, you might think. What’s so hard about paving a road? Glad you asked, because it gives me a chance to talk about civil engineering. Now, now –don’t glaze those eyes over yet! I promise it will be at least slightly entertaining. As a mechanical engineer myself, we used to gently rib the civil guys because their math wasn’t quite as fancy as ours. Now after a decade or three in the professional ranks, I must give grudging respect. Mechanical engineers get to deal with solid things like stainless steel and aluminum. Civil guys have to work with dirt- and like the Inuit, they have seventeen different words for dirt, including six alone for different kinds of “slurry”. Slurry is kind of the crunchy peanut butter of dirt: oily, buttery, and full of nuts. When thinking of road construction, think of a layer cake: First you scrape down to the road bed, then you start putting down some slurry. Unless your road wends over hill and dale as Bohemian Highway does: then you also have to worry about the dirt UNDER the roadbed, because this dirt has an annoying tendency to move around. But back to the slurry: This slurry will contain some aggregate. This is another of those Civil Engineering terms for “dirt”, in this case the aggregate would be the nuts in the crunchy peanut butter: crushed up rocks, sand, gravel (three more words for dirt). Eventually you have your roadbed laid down, and you are ready to put some asphalt on top of it, along with an emulsion to seal it up against the water ingress we started this column with.
So when you get right down to it, a paved asphalt road is just a fancy form of dirt road. There’s nothing permanent about it: Road engineers figure a brand new roadway has about thirty years of life in it. This is where it gets tricky: because our road dollars are not infinite, Bohemian may not get the full thirty-year treatment, the “full depth reclamation” like the one recently completed on Cazadero Highway that is supposed to last for the full thirty years. We might get economy models like the asphalt concrete overlay (15 years), the Bonded Wearing Course (10 years), the Chip Seal (5-7 years), or even my personal favorite, the Slurry Seal (fifteen minutes). No, just joking: slurry seal and its cousin fog seal are only for roads that are sort of in good shape. As we can all attest, good old Boho Highway cannot be mistaken for a road in “good shape”. Okay, here endeth the lesson: keep this column tucked away for the day when they announce when Boho will be worked on, and what kind of dirt solution we will get. Then you can pounce.
