Sunday, February 18, 2007

Driveway-be-gone!

I am happy to announce that our driveway has disappeared. It did not, as my sister guessed, elope with the neighbor's patio. Rather it was murdered, most deliberately and cruelly. Damn but am I proud!

Background

Until three weeks ago, we had a double-wide landing strip of a driveway, 15' wide (plus another 8" worth of railroad ties) and 80' long, stretching from the street all the way to the carport. With another chunk of asphalt up against the street and a walkway leading to and along the front porch, we had about 1400 square feet of impermeable surface, happily leaching toxins from the crude sludge petroleum of which asphalt is composed. From the day we moved in last year, we knew that there was way more driveway than we needed, and that it was only a matter of time until we narrowed it down to whatever footprint we actually need. That, however, didn't stop us from filling it up with anything and everything--wood to be split, potentially useful scrap lumber, painted and pressure treated wood to be recycled, metal posts, potted plants, wood chips, river rock from the yard, etc etc...cleaning the crap out of the driveway was a project in and of itself!

As part of the overall yard design I put together last fall, we decided to remove everything except the strip along the porch, which is in year-ronud full shade anyway, and the few feet extra extending from that strip to the driveway. We considered retaining a 4' asphalt path from the street to the house, carving it out from the rest of the driveway to be removed. But we decided against that, since it would still be leaching toxins into the surrounding soil. It would also have made the project more difficult, as the designated path curves around trees, so carving the path out of the asphalt to remove would have required much more precision and care than a wholesale removal.

I didn't know the first thing about do-it-yourself asphalt removal, and was frustrated not to find any detailed information online. There's some general info in Richard Register's Depaving the World, but other than that the only reference I found was to going "low tech and high sweat, using heavy-duty hand tools." None of this was detailed enough to walk me through what we needed to know. :/ Another challenge was that I didn't even know how thick the asphalt was, what sort of gravel layer was underneath, etc. Our jack-of-all-trades genius neighbor Terry thought it was 6" deep, based on the amount of material he saw brought in a few years back when the driveway was laid down, but he wasn't sure. I dug out the soil in two spots at the edge of the driveway to see what the asphalt layer looked like from the side, and made one exploratory hole about 5 feet into the driveway, using a hammer, shovel, and pickaxe. It looked to me like the asphalt was barely even 2" thick, but I wasn't sure whether the edges of the driveway would be indicative of the depth throughout, whether different places even in the interior of the driveway might be different depths, etc.

Research

I started by finding out what the disposal costs would be. The closest place, about two miles away, costs $25 per pick-up load or $30 for a dump truck load up to 12 cubic yards. I estimated that if we borrowed a pick-up, it'd cost at least $400 just for dumping fees, plus gas and wear and tear. Renting a u-haul would probably be a bit cheaper but would put extra pressure on us to get the job done fast. Next, I called around to get a few quotes on what it would cost to have someone come in and do the entire job for us. I was calling in late summer, and all but one contractor said they were overloaded with work and couldn't give me a bit at the time, or said they'd call back and never did. The one fellow who gave an estimate over the phone said it'd be about $1200-$1400.

Theressa got prices from rental equipment places for demolition hammers (jack hammers) and walk-behind cutting saws. The demo hammers cost about $60 per day or $150-$200 a week and came in weights from 60 to 85 pounds for electric hammers. (Compressed-air hammers exist and give the option of heavier hammers for faster cutting, but we didn't get prices since we didn't want to mess with the noise, hassle, and extra rental cost of a compressor.) Walk-behind saws cost about $100 per day, plus an expected $10-$20 for wear and tear on the saw blade, depending on how thick the driveway was. (With Terry's help we ruled out the saws, since he thought if the driveway were only 2" deep the saw wouldn't work well, and if the driveway were of uneven depth the blade height would require careful adjustment to avoid punching through the asphalt and losing the "channel" of water required for the blade to operate properly.) I also called a sawcutter outfit, to find out what it would cost to have them cut the driveway into approximately 3' x 3' chunks for us, which would be about 650 linear feet of cutting. They quoted over the phone a $1000 cost if the driveway were 6" deep, or $672 if 4" deep. Definitely way more than doing it ourselves, even if it took a full week.

Theressa had the bright idea of asking for advice from a fellow neighborhood association board member who runs the asphalt recycling place nearby. He clued us in to the disposal option of having a 10 cubic yard dumpster dropped off on a Friday for us to fill up (asphalt only--no loose gravel or soil) and have hauled away again for $150 total. Bingo!

The Plan

So we had our plan: rent a demolition hammer with a 6" spade bit (essentially a 6" wide, thin chisel) to cut up the driveway in advance into 3' x 3' squares, small enough to be manageable by two people. We'd line up a 10 cubic yard dumpster over a weekend and fill it up. (At 2" thick, the 1200 square feet of asphalt should take up a bit less than 8 cubic yards.) Then a big work party to load the asphalt into the dumpster, and off it goes! It'd be pretty spiffy if we could coordinate things tightly enough to have a load of chips arrive just after the asphalt were cleared off, to have the work party spread the chips out, but we figured that'd be too hard to pull off, so the chip spreading would just have to be up to me in the days after the work party. We had seven trees in the design for planting once the driveway was cleared out. I was tempted to just plant them all as soon as possible, but decided to minimize chip-spreading work by allowing the chip truck to dump a load at the end of the former driveway closest to the house, spreading those chips in the immediate vicinity and planting the appropriate tree(s) in the area just covered, waiting for the next load of chips to be dumped up to the limits of the former pile's spread, distribute the new chips and plant the new tree(s), repeat etc repeat. Much less work than planting all the trees and having to wheelbarrow chips from the street up to the house.

We expected two major problems with the soil reclaimed from beneath the asphalt: serious compaction and potential contamination from the asphalt. For these reasons we decided the only plants we'd plant now would be the trees, from which we wouldn't eat for two years anyway. In the meantime we'll let the woodchips, worms, and soil life do some loosening up of the soil. We'll also try to establish some tap-rooted plants like chicory and daikon radish to bust up the compacted soil and send organic matter deep down. We'll also try to inoculate the woodchips with oyster mushrooms to help out with breaking down any hydrocarbons still present from the asphalt. After two years of such remediation, we'll feel comfortable eating non-toxin-concentrating plant parts from this soil (avoiding things like the leaves of mustard greens, which are said to concentrate lead from soil and may pick up other heavy metals too?). The understory guilds for a few of the trees include berries like blueberries (half-high and lowbush), lingonberries, and kinnick-kinnick. Depending on how difficult it is to dig in the soil, we'll plant them out either this fall or fall '08.

Execution

I rented a 65 pound electric demolition hammer and found that it cut through the asphalt with no trouble at all. Between myself and Terry, who came over to help out since he misses his old days of construction work, it took 5 or 6 hours max to do the whole driveway! I started by running the hammer a few seconds in one spot, lifting it and sliding it 5" along the line, running a few seconds, repeat ad nauseum. This was very effective. I also tried running the hammer continuously, nudging it along the line as it jumped around. It took me a little while to get the hang of this method, but it's what Terry used when he came over, so I stuck with it and found it to be a bit faster than going bit by bit. Much harder to control the cuts, though, so if you need a straight clean line the bit by bit method is the way to go. The hammer wasn't that heavy, and I didn't even feel sore afterwards. A 70 pound hammer might have been the ideal weight, making the job that much faster and easier without being much of a strain. More than 70 pounds might have gotten into the realm of hard work just moving the hammer around. Ear protection was important, but eye protection turned out to be unnecessary--no flying chunks of asphalt or anything.

A few days later the dumpster arrived and we were ready for the Saturday work party! We set up a few 2" x 6" boards as ramps to get wheelbarrows up into the dumpster. Theressa did a great job of sending out work party invites and rounding up wheelbarrows, sledgehammers, and flat shovels. The day of the work party we had 12-15 people throughout the day, some staying all day, others for a few hours in the morning or afternoon. People organized into teams to break up the asphalt squares into smaller pieces, load them into wheelbarrows, and unload them into the dumpster. My preferred method was to lift up a square on edge by myself or with another person, then hurl it back to the ground. Ideally it would break into two to four pieces, though often it would break into more than that, or require another lift and hurl. Other people propped squares up on rubble and whacked them with sledgehammers to break them up. Clean-up crews followed the main square action, scooping up crumbly asphalt bits into recycling bins to be wheelbarrowed and dumped like the larger chunks.

After just an hour or an hour and a half, we were already about halfway done! The only problem was that we had filled about 2/3 of the dumpster. Apparently there was a lot more dead space created in the dumpster as the asphalt was loaded in than I had expected. Luckily, the dumpster company was able to come out with an hour's notice to pick up the full dumpster and drop off an empty one. So by the time lunch rolled around, we'd filled the first dumpster to the top; while we ate the dumpsters were swapped out and we were able to resume work without a hitch. We filled the second dumpster about half to 2/3 full, so it seems like a good rule of thumb is to double the actual amount of asphalt to figure how much dumpster space it'll take up.

As the main asphalt moving work wound down, people raked and shoveled the remaining gravel into piles dotted across the driveway. It's a good thing we didn't have wood chips delivered, since although there wasn't a whole lot of loose gravel, we definitely weren't ready for spreading anything else out yet! The other final driveway task was to dig out the railroad ties, for which, conveniently, one of our helpers had a good use...so he drove them all away without our having to bother with craigslist, etc.

All in all, the work party was a wild success for getting rid of the driveway. After the driveway project was pretty much done, we set those folks who still had energy left over to hacking back the laurel hedge between the former driveway and the next door neighbor, to open up planting spots and light for a new hedgerow of evergreen edibles. My main lesson from the work party is the importance of advance organization of all the tasks we wanted to get done. We did a great job of figuring out as many of the driveway details as we could, but didn't do as good a job of arranging for pruning tools for the hedge, and didn't discuss in advance how we'd coordinate the two projects. There could have been teams of people working on the hedge while the driveway was still being moved out, preventing the bottleneck in tools we suffered by waiting until the driveway was done. There were also other small projects we'd thought of to which we could assign people, but we weren't organized enough to actually set anyone up with those projects. Directing people, answering questions, and making decisions to deal with unexpected situations takes a lot of your energy and focus!

The Aftermath

The piles of gravel went away via craigslist and the next door neighbor the next day. The revealed soil is almost as badly compacted as I'd feared, requiring a pickaxe to get through the first 4-8" (which seems to be some sort of fill layer of gravel & sand) before finding real soil. I've planted out the seven planned trees, making generous holes and trying to make sure the trees have enough room to expand their roots for at least the first year before hitting compaction. I've also hacked away randomly at different spots in the driveway to make a few starts of holes...hopefully that'll encourage water percolation, root penetration from the taprooted cover crops, and worm wriggling at least in those spots. A more focused application of the pickaxe has helped open up the soil right next to the street, where a natural trough creates a swale. When it was asphalted, we had standing water in heavy rains. After some hacking, the rain seems to be percolating, slowly but surely. Unfortunately, so long as cars are still operating, that area won't be fit for growing, as it's a natural gathering place for oil and other street-surface contaminants. :\ But we have successfully reclaimed a solid 1200 square feet of growing space...go us, and thanks to all those who helped!

3 comments:

greenInk said...

That's awesome! Well done. Less asphalt is always a good thing. More trees and stuff to eat is even better.

Anonymous said...

what are the edible evergreens??? i am so curious.

FarmerScrub said...

Hi greenink,

Thanks for your encouragement!

anonymous,

The laurels are being replaced by a continuous evergreen hedge along the entire east boundary to act as a windbreak for the cold winter winds. Evergreen huckleberries on 6' spacing under the black locusts (which are nitrogen fixers), and nitrogen fixing Silverberries (Elaeagnus sp., using hybrid silverberry and golden silverberries from One Green World) on 6' spacing in non-locust areas, plus salal halfway between all the 6' spaced larger shrubs. There's one relatively sunny part of the hedge in which we're planting two Darwinian barberries (Berberis darwinii) as the main 6' spaced shrubs.

You can see more details on the whole yard plan in my "Fall Plantings" post. One of these days I'll get around to uploading scans of the yard design map and some updates...