Tag Archives: earthworks

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Woodland terraces Fall 2016

This was an earthworks project in the back woods of Waldo county.  The design process for this project started with a concept sketch for the client whose goal is to develop this piece of land into an agroforestry farm with a focus on chestnuts.  The design challenge in this case was the topography and the process of transitioning the species composition of an existing forest.  We got called to consult on the project after the logging operation had been done.

DC design 02 smThe consult led to this cursory design sketch which we then used as the starting point for construction.  We began with a ridge access road to build the first few terraces at the height of land near the northern border of this parcel, highlighted in yellow.  In this case the client was keen to begin construction of water conserving earthworks on this hillside as they had already purchased the chestnuts and wanted to get them planted as soon as possible.  Another challenge to the project was that while the client lives nearby, it is not the current residence, but likely will be for the client’s “next act.”  So establishment of this system may involve challenges of periodic neglect because there are no permanent residents living on site yet.

IMG_7555 IMG_7558The recent logging operation left quite a bit of slash across the landscape which presented a challenge for us to work around.  The slash made layout of the terraces in the landscape especially hard because we couldn’t see the surface of the ground as readily as we would have liked.

IMG_7576We used a water level to find our contour lines and make adjustments for BFRs, BFSs and between-row tree spacing.  I’ve been assured that BFR stands for “Big Fat Rock” and that BFS stands for “Bid Fat Stump.”  The spacing of the terraces was based on the mature crown diameter of chestnuts which we assumed to be about 40 feet in diameter given the forested conditions.  Normally in a field or pasture setting, i would plan on a chestnut growing a canopy of 50 feet or more.  The client’s stated goal was for a closed canopy chestnut grove so that meant we could space our terraces somewhat close together.  The in-row spacing will also be tight to encourage a fast, upright growth habit.

IMG_7584The excavator moved earth, rocks, stumps and large logs while the hand crew arranged slash on contour and constructed our hugel berms.  The terrace itself will serve as vehicle access, pasture and grazing lanes.  The chestnut trees themselves will be planted on or below the hugel berms, functioning as tree planting beds.

IMG_7636For this landscape we laid out the terraces from the middle and worked our way outward toward the ridges.  Since we are working with contour, you can see that the middle of the terraces are the closest points together and then flare out toward the ridge.  Since the middle is the pinch point we had to space our terraces from one another starting from this middle point.  It was a balancing act: we wanted to space the terraces at least 35 feet to allow for full crown expression of the mature chestnuts, but since the excavator was on the small side for this job, we also had to avoid big stumps and great big rocks.  We pulled small to medium stumps, but we wanted to avoid the larger pine stumps.  The result was a between-row spacing of between 30-40 feet.  It was the best compromise given all the other obstacles in the landscape we were designing around.  IMG_7650We did a final grading of these terraces by hand, and so we needed to remove any prominent debris.  Once the grading and construction of the downhill berm was complete we mulched the beds heavily with old round bales of hay we got from the dairy farm down the road.  The seeds present in the hay will introduce pasture species of grasses and forbs into the forest soil seedbank.  We also recommended sowing a pasture mix of seed or something like a deer forage seed mix.

IMG_76522016 was a year of drought in Maine, and while that made it easy for us to do our earthworks it also suggested another issue regarding establishment: irrigation.  I had put an irrigation tank at height of land in the cursory design, but there was no plan just yet for installing it.  I emphasized to the client the need for an irrigation plan given the changing and variable climate.  Under normal climatic regimes you wouldn’t need supplemental irrigation to get the chestnuts established.  But since we’re off the map now regarding climate, it seems critical to provide irrigation to the investment of nut trees.  Fortunately, the client does have a plan now for a gravity feed irrigation tank at the top of the hill.  They will use two 250 gallon IBC tanks placed at height of land to provide irrigation water.  Periodically the tanks will be topped off with a sump pump placed in a nearby dug well.

In the meantime, the chestnut trees got heeled in a temporary garden bed for the winter.  They will get planted out in the spring into the berms on the downslope side of the terraces.  IMG_7690We learned that a concept sketch is good for small residential garden construction projects, however a farm is much more complicated and involves more planning between the concept, construction, establishment, maintenance and how all of that fits into the overall business plans for the farm.  We were able to make this project work because no matter the business plan or the ultimate composition of trees and livestock, this hillside will need access.  We were able to provide that with a ridge path leading to all the terraces we built.

The client learned that starting the design from the tree or vegetation layer can cause problems of retrofitting a landscape design around that vegetation element.  We usually recommend starting with goals first, then topography, water, and access before moving on to designing the vegetation layer, in alignment with the Regrarians platform.  Even though you may read on the internet that permaculture is focused on planting trees early in the establishment of a project, that only applies if your earthworks, access (roads) and irrigation plans are all sorted out first.  And while all of that might be easy for a home residence situation where you already have a residential structure, electricity and plumbing; when developing a site without those assets, the phases of construction should be carefully considered with close attention to goals.

A tighter attention to goals rather than elements makes for an easier decision making process.  In this case most of our decisions were focused on keeping the chestnut trees alive because they had been purchased in the spring before the logging operation had been done.  The client jumped down the hierarchy of design and skipped to thinking about vegetation and trees without consideration of access, water or geography, all of which are higher in the hierarchy of design.  During the drought this year, water proved to be an especially important limiting factor for this design.

IMG_7691There is some distortion in this shot because it’s a panoramic photo, but on the right you can see the ridge road that provides access to all the terraces.  IMG_7701Here are the finished terraces showing the slope we were working with and the lay of the contour lines on the hillside.  The hugel berms are also visible and will provide the chestnut seedlings their planting beds.  Width, size, lineal distance.

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Construction of terraces July 2010

This was the first terrace construction project at my house where i felt compelled to use an excavator to move as much earth as i needed.  This is on a hillside site in Rockland, ME with southeast facing aspect and fine sandy loam soil that drains readily.  The goals for this project are to catch and store water and biomass, establish perennial polyculture gardens and integrate small livestock.

Austrian permaculture farmer Sepp Holzer was very inspirational to me with this construction project.  At first the slope was the primary design challenge.  After watching Holzer’s video “Farming with Nature” it all clicked.  By using the contour lines to my advantage, i could create a series of terraces and ponds.  I had to adapt the patterns of path design to something that would work on a hillside.  My wife wanted mandala gardens with concentric rings of paths and beds.  At first I did too, and it would have been nice, but i learned that that sort of ornate path geometry works best on flat ground.  Sure, you can draw the paths on paper, but when you go to marry the paper design to the real world, that’s when things get ‘ground-truthed’.  So in this case where initially i wanted nested concentric rings as the garden path pattern, i had to adapt it instead to more of a branching pattern.  Larger arterial paths for carts connected to smaller keyhole-style footpaths.  We’ll show a detail of the path geometry in a future article.

IMG_2729This was the height of the verge before i started.  Former lawn that we let revert to meadow.  My daughter is for scale. She’s 2’3″, exactly half my height…give or take…  The first order of business was to cut the tall biomass and set it aside so that we could see the ground and mark out our contour lines.  The verge was separated into herbaceous biomass to be used as mulch and woody biomass to be used as the base of the hugelkultur.

IMG_2736The verge was cut into windrows with the scythe for ease of collection. I used a tarp to pile up herbaceous biomass and move the whole pile.
IMG_2742I had to cut this black locust so i could get the machine down the northern property line.  It yielded some nice logs to use as fence posts, some firewood, and lots of material to use as the hugelkulture base for a couple terraces.
IMG_2761This gives a little better perspective on the slope we’re working with.

IMG_2764This is the lowest-most terrace, the place i started so i could get used to working the controls.  I used a Kubota KX121 rented from Union Farm. I rented it for 12 hours, clocked 14 and burned probably 100 energy slaves (that’s a guess!). The wonders of internal combustion engines and hydraulic pistons! 14 hours and a machine or 10-12 guys and a month of hard labor?  It had a 24″ bucket with 6′ wide blade that could lift, pivot and tilt. Talk about tractor envy!  The thing was so new it still smelled like a new car.
One thing i discovered while learning the controls on the machine was that sometimes there is plumbing below ground!  Luckily it was just a perforated foundation drain pipe, and was easily repaired.  I’m just glad it wasn’t a piece of rigid PVC pipe headed to the septic tank!  I only tore up two sections of foundation drain. The valuable lesson here was that there was subterranean infrastructure.
IMG_2768Here we’re placing large rocks in the retaining wall.  The elevation drop between each terrace is only between 24-36″.  For the 36″ drop i decided to use the big rocks i found in the earth to use as a retaining wall.  For the other terraces, the angle of repose is close to 1:1 which is self-stable and doesn’t need reinforcement.

IMG_2776By now i was calibrated to the controls of the machine that i could scrape off only sod. Probably the top 2-3″ of earth and no deeper. The septic tank was only about 8″ under the surface.
IMG_2777While the load of an excavator is distributed evenly across the tracks, i didn’t want to risk driving over the septic tank, so for this terrace i had to scrape and move earth from either side of the tank.  The advantage of a tracked vehicle is that even weight distribution, as opposed to a wheeled vehicle which has point loads on the bottom of each wheel.  On balance, i think of this as a wise use of remaining petrol resources. These earthworks may well be here for generations, catching all rain runoff and recharging groundwater. The underground water lens will be used to feed an edible landscape.

IMG_2784Once i was past any more underground pipes i could relax and dig a little deeper and go a little faster.  I rented the machine for a long weekend (which meant 12 hours). I clocked 14.

IMG_2787The terraces are not so much dead level as they are slightly pitched backward into the hillside. This way, the terrace can settle and become more level. In the meantime, all rain that falls is caught right where it falls and percolates into the earth.  In the foreground you can see woody debris partially buried. By burying the woody debris from the trees, i turned a waste product into an asset. This buried wood will hold moisture, support the terrace, provide habitat for mycelium and other life, and slowly give up nutrient as it decomposes. I left this part of the terrace slightly high, anticipating some settling over the years.

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