Small wastewater facility or septic system? Whatever you call it, still beats an outhouse!
We thought about doing a grey water system incorporating a couple composting toilets, but the cost nearly doubled, as Laramie County still insisted on a septic tank. Our hope was that the grey water would augment the 13 inches of average moisture we get here on the high plains, to keep the 54 ash trees planted three springs ago, not to mention the lilacs and baby pines viable. This essay is a report of our experience that led to the completion of a small wastewater facility. With Agenda 21 considerations, and local UDC codes now coming into play, you could expect a much different result, if, in fact, you're allowed to proceed at all.
In order to obtain a septic permit, a building permit requirement had to be satisfied. Even though the building was started prior to the building code enactment, I could not get the effort grandfathered in. A building permit did appear after paying a nominal amount.
The diameter of the holes could be four, six, or 12 inches. A do-it-yourselfer might go with a four-inch hole, as they could be completed by hand with clamshell diggers. We had access to a three point hitch/power take-off posthole auger with a 12-inch auger attachment, and tractor to do the job. Before I forget, call diggers hotline to make sure no utilities have been buried in the area. The holes for the percolation test were spaced accordingly, and located within the absorption field. (See Ill. #1)
Six wooden yardsticks were nailed to chunks of 2 x 4 and placed down in the holes for ease of reading measurements. The county required the holes to be filled with water 12-24 hours prior to the test. This would cause the soil particles around the hole to swell, simulating a wetter condition.
The area chosen for the leach field in this scenario is mostly sand and gravel, with a little over a foot of topsoil. Needless to say, the water didn't stick around long. There are USDA reports out regarding soil types, but the county makes you go through the exercise anyway. I filled the holes with water, and waited the 30 minutes, then started taking readings. As I recorded a reading, I topped the holes off with water, and moved to the next hole. By the time I reached hole #6, I'd go back to hole #1, and repeat the process, as it took about 10 minutes per cycle. Of course, the county had to come out to the ranch and see the holes, before filling them; apparently to make sure no endangered species or other undesired behaviors were not carried out. Besides the government, no other persons are trusted in the 21st century I guess. I figure we saved nearly $500 performing the task ourselves.
The county took those measurements I provided, and used an algorithm to produce the estimated length of the leach field. Consideration as to the size of the structure, number of bathrooms, etc., are also factored into the determination, I'm sure.
The computer recommended a 1,000-gallon septic tank (plastic not allowed), and 150 running feet of drain line. Apparently, you can use any configuration as long as it adds up to the desired distance from the tank. We determined that two legs 75 feet in length would be incorporated into the scheme.
There are minimums in the permit instructions. The well to septic tank couldn't be closer than 50 feet, and the well to final disposal needed a distance of 100 feet or greater. The site is 40 acres total, so none of the parameters developed any concerns. I am a little perplexed why water gradient is not considered. Seems like ground water movement would dictate the placement of the absorption field, as much as the other factors.
I mentioned the 54 ash trees we planted a couple years ago. They had four-to six-inch diameter trunks, and stood 15-to 20-feet high. The balls were enormous, and it was all the little John Deere 30 horsepower tractor could do to lift them off of the flatbed trailer, and maneuver the trees into position. Once placed in their holes, the tractor could not lift them back up again. We had used a small Caterpillar Excavator to dig the waterline trenches and holes for the trees with a 16-inch bucket, and realized the smaller excavator would not be adequate for the task at hand.
The septic tank and leach field called for something much bigger. The trenches required a three-foot width to accommodate the infiltrators, or chambers, depending on whom you talked to. Plus, the tank needed to be placed in a fairly deep hole over 10-feet long and probably eight-feet deep. The logic went, that a big excavator would be preferred to expedite the job. The operator didn't have to fool around with adjusting the machine's footing that a backhoe demands, after a stretch of ditch had been completed, and it is actually somewhat easier to operate. Turns out, the bigger Cat is much easier to maneuver than the smaller versions.
A Cat 315 Excavator with the 110 horsepower diesel engine, and 36-inch bucket (one-yard capacity) worked just fine. Barely burned any fuel it seemed. At $575/day, the price could be considered steep, but the digging concluded in less than seven hours of use, whereas the smaller excavator would have taken so much longer, and besides, it wouldn't have been able to handle the tank hole, as deep as we needed. (See Ill. #2)
Running Soil Pipe from the Structure to the Septic Tank
Figuring out the drop from the structure exit to the tank is pretty straightforward. Remember, for every foot in length of soil pipe, there should be a quarter-inch in drop. The soil pipe leaves the structure at two feet in depth. No gain yet, but the initial depth is set. It travels seven feet to the south (pick up 1-3/4-inch), then heads east for 40 feet (a 10-inch gain). So, at the tank, it drops a total of 35-1/2 inches below the surface. This figure is helpful in knowing how far down to dig the trench for the soil line. I watched a contractor put in soil line at another location on the ranch 20 years earlier. He told me the rule of thumb was a half bubble off center at the end of each stick of soil pipe, using a four-foot level.
Length x .25 = Drop at the end, be it a tank, turn, "T", etc. If the soil pipe continues, the drop must be factored in. (See III. #3)
The Septic Tank
The manufacturer of the septic tank will give you some important figures to get the hole ready for delivery of the tank. This tank is 9' 10-1/2" in length, I believe six feet wide, and 5' 6" tall. The important number is the distance from the bottom of the input pipe to the bottom of the tank. That determines how deep you have to dig. In this case it was 4' 6" inches.
The bottom of the hole must be perfectly level, and tamped down to prevent shifting or any kind of tilt. Once the tank is lowered into the hole, adjustments are impossible. The soil pipe can now be run through the tank entrance for in-flow, and the final "T" glued on inside. This can be done from the cleanout hole at the top of the tank. The manufacturer provided a clamp to seal the rubber collar around the pipe on the outside.
I ordered both 12-inch risers and 24-inch risers. As it turned out, the tank lay pretty close to the surface, and the 12-inch risers were kept for the job. We chalked around the inside where the riser rested on the tank top to keep out runoff. Since the caps had wire handles, a steel bar could be used to pick up the four-inch thick cap to complete the tank installation for the entrance side.
Trenching the Absorption Field for the Infiltrators/Chambers
The infiltrator trenching was done the same time the soil line from the structure to the tank, and the tank hole were dug. The grade was fairly slight, but required consideration. The county wanted the chambers at least three feet below the surface. The trenches needed to be straight and the floors level. This dictated that the lowest point along the lines laid out for the trenches, needed to be found. An industrial laser level had been rented, along with a calibrated telescopic truth stick, for the work. The contraption sat on a tripod positioned next to the septic tank hole.
With the laser on and spinning, the truth stick was packed along the intended trenches until everyone was satisfied that the lowest spot had been located by the highest number reached on the truth stick. The trenches would run along the hillside, so the northern trench would be appreciably deeper than its counterpart 24 feet further down the incline. The point where the laser came in higher is value "X" and noted. The three feet the county wanted is added to "X," and an additional foot added for the height of the chambers, to arrive at the floor of the trenches. (See Ill. #4.)
The value "X" came in at around six feet, plus the three feet, plus the one-foot, for a total of 10 feet. The laser never moves. One of us would follow the excavator to monitor the progress. The trench is dug out to the 10-foot mark on the truth stick. If the laser lights up more than the 10-foot mark, the trench is too deep, which is kind of okay. Pulling dirt in to level the floor would be easier than trying to dig it out. If the laser lit up the stick less than the 10-foot mark, the operator would be flagged, and another pass made at cleaning the trench out. In this way, the trench was pretty close to level length and width wise.
The next day, the bottom of the trenches were leveled, and the chambers snapped together. There is no gluing involved. As a side note, the company manufacturing the chambers claims the chambers can withstand loads of 16,000 pounds/ axle with 12 inches of cover. That alleviates concerns about driving over the absorption field and crushing or caving in a chamber. There are end caps that terminate the chamber run, as well as act as entrances, when the desired four-inch plug is removed.
The exit hole (out-flow) received attention. A 10-foot stick of soil pipe was inserted back into the tank where another "T" has attached inside, same as the entrance exercise. A 45-degree PVC angle would direct a short piece of soil pipe to the lateral line that feed both chamber trenches. I found out a "T" would be accepted in place of a cement distribution box, which did the same thing, only cost a bunch more.
The inspection was scheduled for the next day. We wanted to make any corrections deemed necessary while my friend, Sherwood, had his Skid Steer on site. I arrived early to pull tools together and generally redd up the area. The whole system looked gorgeous to me, but considering this had been my first time installing a septic system, I admit to being more than a little nervous. A county SUV showed up at the appointed hour, and greetings were exchanged.
The inspector didn't say anything else. Just walked around taking measurements. I recall the day being pleasant as most are in this part of the country. The hawks were patrolling for the 13 stripped ground squirrels that are so prevalent in these parts. The bull snakes grow large eating the buggers, but don't harvest near enough of them. By the time Sherwood and Ethan showed up, the inspector nearly finished his work and came over to review the results I assumed. All he said was that the certification would arrive by mail, and we could cover things up.
It took most of the day to bury the chambers, tank, and soil pipe. Sherwood used his Skid Steer to backfill. Looked more like he was wrangling the machine, with his expert maneuvering of that stout little workhorse.
The chambers may not replace the perforated PVC and gravel method for hillsides, as they require a level bed to work properly, but they do save on having extra material hauled in, and additional inspections are avoided. I figure we saved three maybe $4,000 doing this project ourselves. I even tried to get bids that included our help, but no one seemed interested in shooting me a bid with that in mind. The bids were all over the map, similar to the drywall quotes I received.
See Materials List, above.
The cap to the septic tank riser lay 25, maybe 30 yards away. It's only been a week since the system was installed, and I couldn't believe vandals had struck. We've never had any trouble to speak of at the ranch before. Size 12 or 13 shoe prints among all the horse tracks is all I could discern. The Tennessee Walkers had stood around the tank to investigate the new addition. They had the mound of topsoil, left over from the backfilling of the trenches, spread and flattened into the pasture.
My certified man-tracking and training experience just couldn't make sense of the impressions in the dirt before me. "Why would they drive up to the septic tank, and not throw the lid in the bed of the truck? Maybe they wanted a crippled-up old guy to haul the 100-plus pound lid back to the tank!" I thought. "Why go to all the effort and trouble of carrying it off, when they could have just rolled it down the slight hill?"
The only other thing out of place, was a horseshoe a few feet away from the wayward lid. My horses haven't been shawed in a couple years. Every 10 weeks the farrier comes by and trims their hooves. One small cutting horse a friend keeps on the ranch, does have shoes, but I couldn't see any missing, and the owner hadn't mentioned it.
Turns out Rocket, the cutting horse, was the culprit. I just can't imagine a horse hooking a shoe on the wire handle of that massive lid, and packing it off as far as he did. The farrier confirmed the little horse had a couple unexplained scrapes that would match a spooked horse running off with the lid swinging from his elevated right rear leg. Mystery solved, except there is no good reason why a horse does what he does except because he's a horse.
Materials List: Septic Tank 1250 gallon capacity $796.35 Risers 12 inch 24.28 x2 48.56 Riser Caps w/handles 18.55 x2 37.10 Chambers/Infiltrators 4'x3'x12" 23.42 x38 889.96 Delivery of Septic System 275.00 CAT 315 Excavator 36"/1 yard bucket 575.00 Delivery of CAT 315 100.00 Total Cost: $2,721.97
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|Publication:||Countryside & Small Stock Journal|
|Date:||May 1, 2013|
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