This summer was a busy time for me on the property. Between finishing the scratch coat on the 10×10 and bringing the utilities to the pad, I was working there about 20 hours a week. Since the septic was one of the bigger projects, I wanted to be sure to recap the highlights here. It took me about 2-1/2 months to complete and get inspected (though certainly not many hours in labor time). Overall, it was one of the easier tasks that I’ve undertaken so far and I saved about $12k in labor by doing it myself.
Earlier last year, I had worked with a perk tester to measure the soil percolation rate and determine the leach field size. I then laid out the septic plans on paper and processed the permit. Although, the percolation rate seemed quick to me (18 minutes per inch), I was surprised that it still required 360 ft. of leach line, according to county guidelines, for my small 3 bedroom, 2 bath house.
For the holding tank, I bought a 1250 gallon plastic tank and lifted it down into place with my backhoe. Because the house sanitary drain will enter the tank about 40″ below grade, the excavation ended up over 9 ft. deep! Digging it out with my non-extend-a-hoe backhoe was a challenge. The dig had to be planned carefully to ensure that it was in the correct location (over 5 ft away from the house foundation) and that I could reach the depth while maneuvering around the excavated dirt piles.
Starting excavation for the septic tank. 
Septic tank installed. 
Backfilling around the tank.
For the leach field, I dug four trenches, each about 90-95 ft. long on contour and leveled along their lengths to within +/-1 inch. I used a perforated pipe over a 12″-thick bed of 1-1/2 inch gravel. The pipes in each trench are connected with a slightly raised (3-4″) section of pipe that runs between the trenches called an “inverted siphon“.
Installation of the gravel was somewhat of a challenge because I only used the minimum allowed spacing between trenches (10 ft.), making it impossible to fill the trench with my tractors, since their wheel base would have been wide enough to collapse the trench walls. In the end, I used a co-worker’s skid-steer and a gravel chute cobbled together from spare wood and an old sheet of corrugated roofing. The 10′-width was just wide enough to drive the skid-steer between the trenches and dump the gravel into the chute. Once in the trench, the gravel had to be spread by hand. (Although, this old-school gravel-perforated pipe method worked out fairly well for me, I probably would use the newer infiltrator-bed type system if I did it again.)
Laying the perforated leach line. 
Vertical pipes at the end of the lines function as “observation ports”. 
The cross-over “siphon” connects from one trench to the next lower one. 
Covering the leach line with 2″ of gravel backfill. 
Laying down geotextile on top to help prevent dirt infiltrating the gravel bed. 
Almost done! 
Adding forms for the dams after the first inspection. 
Dad placing concrete in the forms. 
Completed dam and siphon. 
Caution tape about 12″ below the surface 
Beginning the final backfill… 
All done!
After back filling gravel over the leach pipe and laying the geotextile material, I called my county’s health department for an inspection. The inspector came out a couple days later and looked it over. Unfortunately, I didn’t pass but it was a good learning experience. I had used push-to-fit triple-wall polyethylene drain line from the tank to the leach field, which I learned didn’t meet the code requirement that it be a “tight line”. The inspector also noted that I was missing concrete “dams” on the uphill side of the siphons to prevent the leach water from the uphill trench from seeping into the lower trench rather than passing thru the inverted siphon connector.
Fixing the inspection problems was fairly easy but it took a couple weeks to get everything completed. The inspector was nice enough to allow me to send in pictures of the re-work for final inspection which saved me a re-inspection fee. After the final sign off on the project, I spent about two days back-filling uneventfully. Overall, it was a good project.
