Notes from Windward: #70

Installing a Culvert

late winter is the time to dig!


     A key concept behind what we do, and how and when we do it, is that we're nature's servants--we strive to do things when conditions are right for the task, because doing otherwise involves the unnecessary expenditure of resources.

     Organisms and organizations that waste resources reduce their ability to go forward--ones that do that too often don't survive.

the track-hoe arrives

     Late winter, our ground is wet and plastic, and easy to dig. At least half of the soil in this location is rocks which average about the size of an apple. Stick those rocks together with clay, and when it's dry, it's almost as tough to dig as concrete. When bone dry, that rock/clay composite is great for running heavy loads over, but digging a major ditch is not something you'd want to tackle in the summer heat.

starting to dig on the up-hill side

     When there's a heavy rain or snowmelt, water gathers in the southeast end of the sheep's summer pasture, and flows out onto the driveway. Following one of the tire tracks, it runs down our driveway eroding away the packed rock. Each spring we have to do driveway repairs; this year our goal is to fix the problem by diverting the water away from the driveway.

two-thirds through digging the trench

     The first step was to dig a small pond for the water to accumulate in. In order to ensure that passing loads don't crush the culvert, it needs to be well buried under the road; the catchment pond will gather the runoff and feed it into the culvert.

smoothing out the bottom of the trench

     The next step was to smooth and set the slope of the bottom of the trench. The culvert needs to have enough pitch so that water won't collect inside. In order to protect the conduit, we were careful to remove any rocks that might press up into the culvert when it's pressed down by the top fill.

installing the culvert

     The culvert came in six-foot sections that joined together with coupling rings; quick and easy.

starting to back-fill the trench

     Next, the track hoe started the process of filling in the ditch by placing some of the excavated dirt back into the trench. We then walked along each side of the culvert to pack the fill down around the pipe to give it more support.

the dozer takes over to finish the backfill

     Then the track hoe got out of the way so that the bulldozer could push the remaining fill dirt back into the trench. After pushing the fill into the trench, the bulldozer moved back and forth over the culvert, a process called "walking it in," to pack it firmly around the culvert.

back-fill in place

     As you can see from the pic, the fill dirt is about two diameters above the culvert, enough to protect it from heavy traffic. But the job's not finished because the jumbled up fill dirt won't form a surface that's strong enough to stand up to vehicular traffic, especially there where cars are turning off of Windward Lane into the main area.

bringing in a load of crushed shale

     To create a traffic worthy surface, the next step involved bringing in a load of crushed shale rock from a quarry about ten miles away. Because it's angular and composed of a range of sizes, the shale will pack down and form a strong surface.

spreading out the shale and walking in it

Notes From Windward - Index - Vol. 71