Hi XXXXXX;
The two things you need to be carefull with are the soil the pipe rests on, and the first 6-8" of soil you put over it.
The soil it rests on must be natural grade undisturbed soil with 6" of clean sand or fill with no rocks bigger then the end of your thumb (1") in direct contact with the pipe.
Alternativly you can use fill dirt, and mechanicly compact it with a "Whacker-Packer".to prevent any 'sink hole' effects from breaking the pipe.
The last thing you want is the soil under the pipe to start backing away from the pipe in a few years. Not only can unsupported pip[es break but any bowing can cause the effluent to pool at that low point. This will eventually cause all kinds of problems in the future.
The main purpose of the 6-8" of clean sand or fill dirt (commonly called "shadeing") above and below is to discourage large sharp rocks from penitrating the pipe over a period of many years. Unless specificly called out for on the permit approived set of plans you can use the existing natural soil to burry the line.
Some areas require that sand, slurry, or possibly even concrete be used depending on the soils annalysis of the area, and other factors. This must be refered to the engineer of rercord. That way it will be their tail end that is hangeing out in the wind if the system fails.
One other concern is trees and other plant life getting into the system. Laying a strip of 8 mil black plastic over the pipe prior to top shadeing and cutting any roots back as far as is practical Will help prevent root incursion for many years to come.
Please post any other concerns here.
Best, THS
I just need to know the proper way to backfill a replaced sewer line to
prevent soil erosion and leave a ditch in my back yard.
Preventing errosion can be done in many ways.
Planting grass is the easiest method and also the cheapest. A bag of grass sead is less than 10 bucks. Once the grass is established it will hold the soil against quite a bit of run off.
Stepping the soil with landscaping materials is a good option. Something like placeing an old railroad tie every 4-6 feet will prevent the run off from gathering speed and washing the soil away.
Other than that all you really need to do is fill the ditch with soil. To keep the ditch from sinking and leaving a low point for run off to gather water the backfill down as you put it in the trench. Walking it down every foot or so will compact the dirt pretty good if you wet the fill dirt good. Dont make mud but add enough water so that if you picked a handfull of dirt up and squeeze it it retains the shape.
Once you have the trench filled add a little bit more and leave it rounded instead of flat.
That should keep you from having a low point where the trench was.
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