Septic feasibility over explained

You have septic approval but what does that mean?

I want to help to explain the process of septic feasibility and get in depth on the subject of septic approvals in Oregon. (Disclaimer)This is a touchy legal subject and it is only through research and arrogance that I feel I can speak on behalf of all Oregon counties given my personal experience has mostly been in the confounds of Deschutes County, although a septic installer license is good state wide. With that said, I also have found that most states tend to work in the same fashion so if you live in Washington or Virginia I would hope some of this info is helpful. IF not, sorry, but I am going to try to clear up some shit that I hear all the time in hopes of stopping panic and disaster when you read your feasibility report from the government.

Let’s start with a simple path of how our government works. The DEQ is the governing body that sets rules for all sewage disposals and it is important to note that the government refers to sewage disposal as “environmental soils”. This is the most literal term of what they are trying to protect, soils. I know it’s odd for a government agency to use terminology that actually makes sense but they had to hit one out of a million right on the head. At the federal level, environmental soils rules are set for the country through math formulas based on current and projected population growth, water tables, yada yada. I am sure the list is way too long to care about and likely includes more aspects of soil contamination than just sewage. So, the fed simply sets up guidelines that mandate an acceptable line in the sand they would never let a state cross and from there it is the responsibility of each states own DEQ to make statewide rules. Side note, this is pretty much how our government works in general with regards to most governing bodies so this shit applies to that shit if you don’t over complicate your thinking.

Now that we have these guidelines from the Federal DEQ the state can set up rules however they see fit their own way. To make it very clear, you will never be dealing with the federal government on your private property septic feasibility unless you are one of the few who have leased land inside a national monument or park, fed out! Ok, in Oregon’s case the Oregon DEQ put together something similar to what the feds did and mandated the finalization of septic feasibility to each county, but they are not out like the feds, I will explain that later in this blog. Thus, when you are applying for septic feasibility in the State of Oregon you apply to the Environmental Soils division in the county for which your property lays, coppice.

We are now down to the county level where you have applied for feasibility and your hopes and dreams are now in their hands. You should firstly be praying to whatever form of a god you believe in that your property passes. This is the most important step because if it does not, you may never be able to build there at all. And I say “may never” because you’re not 100% screwed just yet, but we will get to that below. You can allow yourself to dream of the words “standard system” (obviously much cheaper than non-standard) being on your approval letter in a near second to getting approved. I know it is hard to put cost second to possible for most of us but I feel this is a necessary evil to keep from being crushed by an approval for the most expensive septic you can imagine. It’s almost as bad as a denial. To sum up how the government works, for the average person who owns or is looking to buy vacant land and then build a home on it, you will be dealing only with your local county government. This applies inside city limits as well. For instance, the City of Bend has no environmental soils division and relies on Deschutes County to work with them for all septic related projects. This is also how things like the latest city sewer expansion rules end up involving the county. I may write a different blog on that matter because it is way more a shit show than just getting bare land buildable.

Now, with the governments line of succession explained, you should know who you are dealing with at least. Things get kinda fucked up from here so bare with me. In my opinion this process is too vague in its rules and has resulted in so many disasters that should never have happened and that is one the reason I am writing this. In the infinite wisdom of the Oregon DEQ they decided to allow some weird shit on how you may go about getting this septic feasibility done. The weirdest is the allowance of “anyone may choose the location of and dig to spec the holes required for testing purposes by the county inspector” (that is not word for word the law but it sums it up). UGH! Before you run down and rent a backhoe or ask your neighbor Bob with his tractor to just flop over and dig you some holes, please consider these things.

You need to know everything about your property before deciding where to dig. Your septic approval is not for the entire property, it will be for an area around where your test holes are dug. I love examples so here is one that should apply. You have an acre of land, you have a good idea of what your house and any other structures are going to be and you have a good idea of where they are going to be on your lot. If you know that much you are ahead of the curve but you are missing many details. Like, how large of an area will your drain field need and what are its setbacks. You cannot build a drain field in any area you plan on anything being that may compact the soil, so it’s a no go for under your driveway, RV parking areas and even livestock areas. If cost is a thing, as it always is, you will need everything to line up to your plumbed structures in a path most likely to be gravity fed by no less than 2% fall (general rule of thumb you need 2 inches fall in every 10’). You will need to have an understanding of your properties elevations and what may lie beneath the topsoil; rock and water tables are real things and are expensive to deal with. Basically you need to set up a visionary plot plan of any property you want to build on and then decide where to put those test holes. In the example of an acre of land, it may look like there is plenty of room for everything. But, more often than not, people jump in there and dig holes in the wrong place because an acre fills up quite quickly with a 2400sf house, 2000sf shop, driveways and that spot for your daughters’ horse. Your chances of a septic feasibility approval are increased dramatically by simply having someone like myself, a licensed installer, meet with you on the land and take a look-see. Hell, I do not even charge for that, unless you ask me to drive all day to get there. Just call and set it up or put your realtor to the task, they might as well earn their rather large commissions.

This also applies to buying property with septic approval. Take a good hard look at the space that has been approved and think hard about whether you can build around it or if it’s in the way. Your structures are allowed to take up space within the area approved for a septic but there still needs to be room for your initial and reserve systems (a reserve area is the same size as your initial system in most cases). For instance, you’re looking at a lot that is ¼ of an acre and it has a viable septic approval (which is a selling point that you will be paying for) but that is all the farther you look. You buy the lot all excited that you will be building in no time then you get with the bank who immediately tells you to contact a septic installer to design you a system because the septic is the most important piece of the puzzle to them (no septic = no house). So, you contact an installer who looks at the feasibility report, which you should have already studied, and they say “looks like your approved drain field is smack dab in the middle of that lot and will use up about 1/3rd of your ¼ acre. Yikes, you have nowhere to build that works besides right by the road most likely. The road you were trying to get as far from as humanly possible which was the whole damn reason you bought that large a lot in the first place. Suddenly it occurs to you why all the houses you see on lots this size have houses by the road and all that laughing at those silly idiots you did while shopping comes home to rest. LOOK AT THE FEASABILITY BEFORE BUYING. Don’t be one of the silly idiots!

That was a bit of a rant based on how many times I have had to go dig more holes for someone who has either bought property with feasibility in the wrong place or let Bob wonder around and make his own decisions. FYI, that shit aint free and it may not just be me charging you. Your test holes can be replaced and re-inspected for a short period of time after an approval or denial by the county. They are not in the business of coming back so if you pass the time limit, I believe its 90 days in Deschutes County, then you will be paying for an entire new septic feasibility study. Sucks, but it is what it is. So please pay attention to these details, I dislike being the bad guy that has to come out and tell you where you can or cannot build your house without spending another fortune.

Let’s get into approvals and denials and your options once the county has put it on paper. First, an approval needs to be interpreted for most to understand. There is an approved area based on the test holes provided and there will be a crappy drawing of your lot with that area outlined provided in your approval paperwork. The county employees are good at their jobs but drawing is not in the job description, hence the crappy drawing. There are more pages in the approval that will have many details of exactly what you will need to install based on the information provided to the county and their findings. For instance, we count bedrooms in Oregon, not bathrooms, laundry rooms or kitchens (while these would make more sense it is about possible occupancy and not your desire to run every faucet in your house at once), and that will set the size of your septic system. If you put on your application that you’re building a 4 bedroom home and then decide later to build a 1 bedroom apartment over your shop, expect things like tank size and drain median to increase and were back to deciding whether or not that will fit in the allotted approved area. It’s the circle of shit. Then there is the words standard, modified and ATT (Alternative Treatment Technologies) which are baffling to say the least. But if you look at all the little boxes you will see what they have required for your system to exist. What you won’t see is definitions of what they mean or paths to changes.

Let me try to clear those words up a bit. You may have the word standard written in the box labeled tank type (or possibly in your area it could be labeled initial treatment) and then you see the word standard in the box labeled drain field with the minimum linear feet required. Yeah for you, especially in Central Oregon where that is a rarity, you achieved the hat trick of septic systems. You’re only required to install a properly sized tank that gravity feeds a properly sized drain field, which is denoted in the box labeled drain median required, thus making your system the standard and cheapest possible. Around here the most common thing you will see is a standard tank with a modified drain field. A standard drain field, or rather “equal distribution” would be one drop box with lines reaching out that are all level to each other, easy. These can be looped for extra space, run a maximum of 150 feet in any one line and can be installed in pretty much any fashion that meets specs including things like bowing around tree roots and such.

A serial distribution will have a drop box on each line and are used due to a slope in the approved area. They work as described, in a serial fashion, where the upper most distribution box distributes effluent (that’s the name for the treated fluids that leave your septic tank for final destination) to a level drain line from only that d-box. Once again you can bow them as needed but they cannot be looped in any way. Once the upper most lines have saturated the ground to the point that it starts backing up in the d-box there is a crossover line that feeds the next d-box, and so on. It’s pretty simple really but has a few more parts thus raising cost of installation slightly.

A curtain drain modification is rare as fuck in Central Oregon but used often in the hills of the Willamette valley and coast. Central Oregon has little actual rainfall and when it comes to steep slope building you are likely into solid rock, so these just are not used. But the general idea of a curtain drain is a series of ways to divert surface water away from your actual drain field as to not over saturate the ground around it. They are typically above the slope of a serial distribution and use trenches made into what are most commonly known as French drains where some loose rock can catch the surface water and a buried perforated pipe below will divert it to wherever you slope it to go. Not rocket science but kind of a spendy addition to your septic system.

WTF is an ATT?

Beyond the standard system everything else is considered to be an ATT (Alternative Treatment Technologies). Keep in mind that no matter what is added you will always have a septic tank in the start position. An ATT can be a treatment tank, a modified drain field or a combination that works for your location. Rest assured that no matter how you look at it, ATT is the most expensive acronym in the residential septic world, but often a necessary evil if you want to build. There are a few types of ATT’s and I want to help you understand them better. Sorry if my opinion gets in the way.

The most notable ATT created in years is the treatment tank. Here in our area we are only allowed by the county to use the Orenco ATT for this, but as far as I can see they are mostly the same across all brands. It is a rather large tank with an exposed lid (4’x8’) that goes next to your septic tank in a serial fashion (it’s a big green eyesore no matter how you look at it). Once your sewage does its thing in your septic tank it is then fed into the ATT tank where it is circulated by a pump through a bunch of filters that pretty much look like the ones in your cold air return for your HVAC. They are easy to look up so I will not get to intricate with the details but the idea is to remove more contaminants than a static system can, and they reduce nitrates through the circulation process. It also has its own cool control panel with an alarm loud enough to wake the dead, so that’s fun if it ever encounters a problem. However, the most notable thing for this exercise is that they are damn near as big as your main tank so the hole is getting pretty big for installation.

From this illustrious ATT there are a few modified ATT drain field types. Let’s tackle the cap and fill first, the tank had its own paragraph. A cap and fill is typically used on shallow soils where we hit solid rock in the first few feet. It is not legal to hammer out trenches for the purpose of drain medians so instead of that, we dig down a bit and then put approved dirt on top of the pipe. This approved dirt will be the most expensive dirt in all the land and it is a task to spread it properly without over compacting it. Also, the math on how much is needed will make you cry in most cases. A typical drain field will have 300’ of drain median in it (in a lucky twist of fate with a system that starts with an ATT tank the cap and fill will likely only require half of that, yeah?). Here is the math of it if you enjoy story problems. The trenches need to be a min of 11’ apart to the centers and there needs to be 10’ of this cap built past each side. An area built for 150’ of drain median will typically set up as 3 - 50’ lines. The cap for the initial system will need to cover an area about 52’w X 72’l at a depth of typically 1.5’. So, we take 52x72x1.5(27)= 208 cubic yards of material. You will be lucky if you only pay $17 per yard in the land of overpriced dirt winding up with a final cost of materials around $3536.00. And now it needs installed like a baby blanket over the entire area which is an expensive excavation process. OUCH! To make it worse, you may be required to duplicate the cap in the reserve area so it can be used in the future. That’s just bullshit as far as I am concerned but the powers that be are in charge, so double up.

Ok, that’s enough maths for today, but you are getting the picture. In this common example you are in $3536 bucks just for some fucking dirt to cover your drain field because your lot requires a cap and fill. I will not go into labor costs but rest assured, dirt wont spread itself and drain median is spendy crap too. Grey cloud in the example is, that’s not all! An ATT tank was thrown into the mix of this cost mountain and as of today, Jan of 2022, they average about $10k to buy. If you’re still with me and are not crying, remember the fact that we had to use a cap and fill because we hit solid rock fairly shallow? That comes into play with the tanks now because the most likely case scenario is that the rock is everywhere. Hammering a hole that’s 10’Wx12’Lx6’D is an undertaking all its own and will cost a ‘plenty. Ok, the example is scary but, once again, I hate being the bearer of bad news in person and this set-up can run over the $30k mark pretty fast. Not my fault, the county did this to you and if it is required by them then you WILL be building it if you want a house.

Another example is the ATT tank to bottomless sand filter, which is a common combo in South Deschutes County from Sunriver to LaPine. You know about the tank, nothing has changed there, silver lining is you do typically get to save money on hammering rock since its all pumice as deep as you can go in most places. The ATT known as the sand filter is now your drain field. It is a box built into, and above ground, filled with gravel and sand in layers to filter your effluent more efficiently than a standard drain field would. You can look them up easily just like the tanks so no need to overdo it here, but they are difficult little bastards to build and costly. The use of the sand filter is mostly due to water tables in particular types of soils, like pumice. These little fuckers have about a hundred options and are the most common thing that can be changed in an effort to overcome a septic denial, which we will get to in a different blog post.

The tank, cap and fill and bottomless sand filter are the 3 ATT’s we typically use here. There are things like aerators, yet another tank that uses air circulation to remove nitrates, but I have no experience with them. I do know that they are more common where the ground has dirt with higher clay contents than here. So, I think we have pretty much covered what might be listed on your septic feasibility report and what each may mean. I should point out that nothing I have written to this point are mutually exclusive to each other and the only thing set in stone is that you will be installing a septic tank no matter what is required.