Written by Doug Crouch
To implement an earthwork within a landscape can be a rather simple choice when the correct protocol are in place for its inception. Thus in this article we will look at some of those factors and complement it with design principles that help you to select the right earthwork in the right place from a well understood context. While it’s a simple choice, there are many factors involved and this regenerative technique should not be taken lightly, especially when done with the power of fossil fuels and machines.
Papaya circle planting, Dominican Republic, 2012
Due Diligence
This first checklist allows you to quickly check off some requirements as to know if you can implement an earthwork or not.
Stay away from foundations
You must go at least 10 feet or three meters away from any house foundations when it comes to water infiltrating earthworks.
Call before you dig
This is a popular phrase in the states because you don’t want to hit any utility lines. Thus with utility crews layout exactly where all lines are so you can design around that. If you are in a rural project, where wiring/piping has been done in not as a professional way, be sure to get an opinion of where every line is from as many people at the project as possible.
Only intervene when necessary
Earthworks are a disturbance, only do it if necessary, not cause you saw some video that made one of them look cool. If there is not an obvious flow coming into that area because of whatever reason then don’t do it. Again, simply don’t do it unless necessary. People want to do them sometimes without the right context of obvious water flow, the right soil types, the correct slope % correlating with the right earthwork, and other factors covered below.
swale jungle, a swale in my parents back yard which collects huge volumes of rainwater, which was easy to see the need for intervention because of large hardscape and landscape runoff
Ask for advice from professionals
If you have any doubts on what you are doing consult engineers, the drivers of the machines, and permaculture consultants. In some places of the world you need to ask for permission from the government and will require a design or approval from an engineer. Make sure you understand your local laws well and do not be afraid to consult an engineer. In some parts of the world, it is a highly beauracratic process to build a dam so make sure you know the laws before planning/ designing such a project. Rumor has it, so I can’t immediately verify this claim, that several well-known Permaculture Earthwork fanatics have brought down mountains, better known as landslides, from being too cavalier around this point. One I can verify is that one of these earthworks fanatics charged a client big bucks for a design in Southern Spain that included dams in a region where it’s practically impossible to build one because of water regulations. I consulted afterwards and recommended keyline, which is a great earthworks strategy because it uses a subsoiler and a tractor not heavy machinery at its most basic level. Therefor no government approval is needed and is the best choice on the Broadacre for many reasons including price.
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- Before contour bench terraces implemented at Edible Tree Crop, Nelson New Zealand 2007. I worked with an engineer to design it and his insight was vital
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- Atamai Ecovillage in Motueka, New Zealand 2007, same engineer designed these contour bench terraces where i was hired to plant trees.
Contextual Design Parameters
To make the correct decisions on earthwork inception into the land a few more tangible factors need to be examined.
Soil Examination
Over and Over again I hear people wanting to make things like water retention landscapes or even swales in soil contexts where it simply is impossible. If you are wanting to build water retention dams or ponds, you must examine the soils before ever approaching such an endeavour. Even if you are in clay soils, as we are at Suryalila Retreat Center in Southern Spain (2017), you may not be able to build dams. We were told this but the owners wanted to do a test dig anyway, which cost all of 50 Euros and we found exactly what the driver said we would. Broken junk base rock about 1.5 meters down making any dam digging of any size obsolete. Also, as it pertains to the next point below, if you are in an area, like my families land Treasure Lake in Kentucky, USA, with sandy soil and not a huge runoff potential say from a large road catchment, there is no need to build swales as the water seeps in the ground anyways. Thus in that part of the land there at Treasure Lake there is no need for intervention where across the valley in the heavier clay soils there is. Also if you have heavy clay soils, there is a much bigger risk of landslides and often warrants the advice of a professional.
Match Earthworks with runoff- observation leads to calculations
With observation of your site over a prolonged period, you can make a choice whether to intervene or not. Once you see visible runoff then determine the catchment for that particular areas runoff. It might be a roof, coming from a road or a broad acre landscape. Once you know the size of the catchment, do the calculations that help you to understand how much water would possibly be moving through the site in varying rainfall amounts. This allows you to design earthworks based on actual data so you are not over or undersizing earthworks in general.
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- runoff observed
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- Catchment area for a swales and terrace project, Suryalila, Spain 2016
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- For the same area the calculations, Suryalila, Spain 2016
Layout contour lines in the field
Using whatever surveying equipment is available, (A-frame, bunny, transit or dumpy level, or laser level) measure contour lines in the field to really get an accurate picture of lay of the land. Contour maps help but the detail in the field often comes out slightly different from what was on a topographic map. Place flags along these contour lines to mark them so you can read the landscape more accurately.
Calculate slope to match earthworks
Many people have asked the question to me about putting swales in steep country. I point this out because you must match your slope percent to the earthwork. If the land is steep you must switch from swales to terraces for example. Use a bunyip level and a measuring tape to see the drop of the land over a given distance. You can also do this with topographic maps but they may not match up to the in-the-field reality. However it can be done as a helpful first step, but should again be measured in the field.
Before contour bench terraces implemented at Edible Tree Crop, Nelson New Zealand 2007. I worked with an engineer to design it and his insight was vital
Design Earthworks
I like to do schematic designs on computer maps or paper maps to get a rough idea of what earthworks I will implement based on the above factors. Again because contour maps don’t always line up to the in the field reality, I then go to the field and lay them out with much more precision. I use varying colored flags to easily be able to communicate with the drivers of the machines of crews working by hand the design and subsequent implementation.
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- Contour layout
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- lines marked for earthworks
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- Schematic design of plantings
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- Earthworks capacity calculations corresponding runoff with earthworks size limits
Project management/ have all resources set to go afterwards
If you are to intervene in the land with earthworks, you should have all necessary inputs needed for land restoration ready to go before the digging ever commences. Of course this repair work comes in waves so you may not have all of it totally in order but it will require certain facets be ready to go immediately. These include way to cover the soil like cover crop seeds and/or mulch, ways to repair soil biology like compost extract or compost itself, water, and ways to stabilize the earthwork like trees and possibly their associated guilds. Be sure to do the digging/ land alteration when the soil moisture is correct leading to the timing aspect of project management. Budgets should be laid out and communicated well to the client and the earthworks again are only one of the budget items as these other necessary items must have budgetary allowances. Accrue all the resources then press play on your implementation including labour as the final earth sculpting, tree planting, cover cropping, watering, mulching, and all of that process requires skillful direction and hard labour.
Home made nursery at Suryalila to receive the hundreds of trees, bare root and in pots for planting after earthworks.
Save top soil
If there is any top soil to be saved, plan that into how the project will flow and the design. I find that where I am doing earthworks rarely has much top soil since this is part of the reason why the water is running off. However if you do have both, set it aside for a later top-dressing to help repair the site sooner.
Design guidelines
These guidelines mimic the principles set out from Brad Lancaster in his book Rainwater Harvesting for Drylands and Beyond: Volume II yet I blend them with Mollison’s principles to keep a basic language. They are meant to be a sense for analysis and assessment then planning forward.
Begin with long and thoughtful observation= pato
As do all systems management, it starts with observation, and the longer it can be the more effective it will be. There are various signs of water runoff if you are not able to see runoff during rainfall events, as if you are in consultancy timing. Look for hardscapes, obvious signs of erosion, organic matter movement and deposition, valley to ridge relationships, steepness of the slope, aspect, and soil types. Examine both the landscape itself, satellite images, topographic maps and contour lines staked in the field to get the full picture. Also ask questions to anyone who might know any info about runoff on that land or in the area with similar soils.
Start at the highpoint of your watershed and work your way down- energy cycling/slope
If water accumulates volume and speed, a greater need for larger earthworks exists where if you start at the top of a watershed it is the opposite. This isn’t always possible because of landform and boundary lines but sometimes it is. Also roofs are technically a highpoint on the land and never forget to look to them as immediate sources of runoff, quickly building speed and volume from them. Thus we examine the slope context, just as Bill asserted in his energy-efficient planning. From here we zig zag it around the land with the energy cycling principle by beginning at the top so our earthworks can be smaller and more manageable.
Start small and simple= scale intensive/ least change greatest effect= slow, spread, sink= plan overflow=
When you start at the top you can initiate with smaller earthworks and make your earthworks embody the least change for the greatest effect. From there you can stair-step down the hillside and throughout the watershed that you have influence over. In this way you are able to develop nuclei in the sense of small-scale intensive work. These nuclei consist of the earthwork, the planned overflow route and the multifunctional living sponge that comes after; stacked in space and time. Also by starting small its much easier to do the project management, implementation and subsequent management to make sure the earthworks stabilizes and succeeds. Also if you receive feedback loops and need to make adjustments then it is much easier. Furthermore each earthwork will have an overflow as once it fills to capacity it will need to spill-out and onto the next earthwork or your planned overflow route. This is a critical choice in the design process so you can do this stair stepping down the landscape.
Small scale as high up in the landscape as possible to meet dome runoff, Suryalila, Spain, 2016
Living sponge/ accelerate succession
The living sponge is a mix of trees, herbs, compost and mulch along with creative human interaction to rehabilitate the ecosystem also known as accelerating succession. Forests naturally absorb more water then beat up ecosystems by infiltrating more water so with infiltrating earthworks you are already accelerating succession through these edges in the landscape. “Plant the water before you plant the trees”, as Mr. Phiri said. But then once you plant the water have those seeds, those plants, those trees, and those resources to rehabilitate the soil as soon as possible. Compost or compost extract, if compost is limited, helps to get the microbes seeded again, which is vital to the earthwork becoming a sponge. As the microbes work and live with living and dead plant material they will build soil organic matter percentage thus holding more water and also increasing the infiltration rate. The plants themselves help to cycle organic matter, create shade, symbiotically combine with micro and macro organisms, slow wind, and hopefully be multifunctional.
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- Swale dug with trees planted, compost added, and mulch and guild plants added after that
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- Swale dug
Make it multifunctional
When implementing an earthwork also make it have multiple functions by making it beautiful, produce food, produce biomass, and even create access or social spaces. There is a myriad of combinations but tap into that creativity to make these functional interconnections occur and have the abundance that follows. The plant selection should focus on this as well thus matching inputs and outputs; relative location.
Swales dug with two terraces, one above not seen, for social space creation while also acting as a water infiltrator with food producing and bee fodder vegetation added on terraces, Suryalila, Spain, 2016
Keep going with observation/ feedback loops
As you implement, as the rains come, as soil moves, as plant grow and mature, always be observing with that keen eye to make those much-needed small interventions to tweak. And at exactly the right time, in the right place, this is what it means to be a sculptor of the earth!
Swale filling with very light rain, seeing adjustments that need to be made. Suryalila, Spain, 2016
During and After Implementation
Ask for permission from land
Coming into the land with an aggressive tone can disturb the subtle vibration of a land even with the best of intentions. A simple few moments of “letting the land know” will go a long way. Let it know that this quite violent action is there to help in the end. This might sound a but far off but trust me, it helps.
Doug Crouch PDC terra mae Permaculture Portugal terraces rain garden. a land we should have asked permission from
Design explanation
When the crews arrive and/or the machine driver, clearly communicate the design and what the flags mean. If you have examples on site already make sure they see it beforehand so the picture lets them see it already. Ask the driver what he/she thinks and make sure the equipment you have there is going to do the job right. Ask the driver the capabilities of the machine in case you are in tight territory as they will know the equipment capabilities better than you.
Observation and Execution
Always keep a careful eye on drivers of machines and crews of people working. As fatigue sets in corners can be cut and precision lessened. Make sure you keep a watchful eye and a motivated attitude. With machine drivers most of the communication is done through hand signals and eye contact after the initial design is explained. Never hesitate to slow the drivers down or the implementation crews so things are done to the specs of the design. Be prepared for in the field alterations as once you move the earth there are always small adjustments to be made.
Finishing by Hand
If working with a machine, make sure you have the right hand tools and enough labour to finish the job correctly. Machines can do very fine work but with a crew the project can be hastened with the machine, which is often very costly, and human labour can finish the earthworks.
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- Crew with tools, getting ready to hand finish one swale while terraces and other swale being worked on. Suryalila, Spain, 2016
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- Sam capping the edge of a swale, Suryalila, Spain, 2016
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- Swale fine tuning, Suryalila, Spain, 2016
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- Hand finishing as the machine goes down the line, Suryalila, Spain, 2016
Stabilizing the system
As mentioned in the project management section above, you should have all the necessary trees, compost, seeds, plants, tools and labour ready to finish. Once the earthwork is complete it most often by the following combination but there is always a variety of approaches:
- Sow a cover crop to get a ground covering biomass producing plant mix going quickly and cheaply
- plant trees immediately and subsequent guild plants if possible to stabilize earthwork, protect exposed edges from erosion and drying effects
- Add compost to the disturbed earthwork or spray a compost extract if the solid resource is limited. This helps to repair badly damaged soil biology that occurred during the digging process.
- Mulch around trees thickly and lightly the rest of the earthwork where the trees aren’t and the seeds are.
- water in trees and seeds
Ongoing maintenance
One key to earthworks longevity is in the beginning keep a watchful eye on them. See what needs to adjust and how, in particular, soil movement in the beginning. You may need to clean some of this up after the first rains and make adjustments. Also you should keep going with restoring soil biology by again applying compost or compost extract. Keep planting trees and guilds and mulching to keep the earthwork stabilizing if it wasn’t all done straight away. Plants will die, some will thrive, some can be propagated while others will spread through seeds as the seasons roll over. In essence you earthworks become one more element in the bigger scheme of things and will need skilled management and attention. However when earthworks have been given the correct attention to building a well understood context, they are a fantastic choice in the landscape for doing ecosystem restoration.
Written by Doug Crouch
Header Art Bonita Edwards
