Septic drain field restoration... can you replace the dirt?

[ethilo]

Hi all,
I just moved to a new house July 2022, it was part of a brand new 6-house development built in 2017 here in Gig Harbor, WA. It's a 3 bd/4ba house with standard septic tank + pump chamber + 4 horizontal laterals across the drain field (our backyard lawn). The sellers put on their disclosures that they jetted the laterals 2 months prior to the house sale and a follow-up inspection said it was good to go. Over the summer until now we've noticed a soggy lawn and as we moved into the fall and winter we've noticed every so often the end caps on the laterals will start pouring effluent out of them during a pump run. Pump runs every 3 hours. The next door neighbor said multiple houses have had similar issues here, he also reported my seller did a terralift about a year ago and he didn't disclose that in the seller's disclosures paperwork.

A septic company said we could either terralift again or redesign the drain field as our only 2 options.

It seems very odd that we're having this much of a problem so early in the drain field's life. The soil in our neighborhood is noticeably very compact with lots of aggregate in it and my neighbor wonders if it's from all the heavy machinery driving over it during the clearing of the land. During rainstorms the ground will be a sheet of water that rolls downhill into the marshlands nearby. I have a high suspicion the earth is low quality.

I own a subcompact tractor with a backhoe, we tried planting a few things since living here and found we had a lot of trouble just digging a hole to plant some bushes because the earth was so hard.

Questions I have:
I wonder if anyone has any ideas of things I could do on my own?
Could it be possible the builders laid down laterals without encasing them in washed rock and filter fabric? I'm wondering if I could just dig up the laterals, maybe widen the trenches, put fresh fabric and washed gravel in if that could resolve the issue.
Is it a viable option to dig up the dirt surrounding the laterals and replace it with different dirt?

[lthenderson]

In my experience septic rules are very strict and vary widely upon location. I would first go to the local agency in charge of septic tanks in your area and see what is required and what can be done before coming up with a plan about what to do in your situation. By changing something with your system that might not be allowable, you are opening up yourself to fines and lots of trouble when you go to selling your house.

[Sanitary Stache]

You should definitely call your regional office. This looks like the contact page

https://doh.wa.gov/about-us/washingtons-public-health-system/washington-state-local-health-jurisdictions

Such a new septic system should have design and soil testing on record.

I have never heard of a terralift, google says it is potentially a solution for soil compaction. But poor soil quality may be due to reasons other than compaction. The local health office should know more about your septic system and the soil in your area.

[GilesMM]

Get the installation schematics, name of installer and have them come take a look and explain themselves.  If they can’t or won’t fix it, get a professional who can. Maybe pump can be adjusted to run less volume more frequently. If you start backhoe-ing be prepared to demolish some lateral pipes and have to replace them.

[BudgetSlasher]

In my experience septic rules are very strict and vary widely upon location. I would first go to the local agency in charge of septic tanks in your area and see what is required and what can be done before coming up with a plan about what to do in your situation. By changing something with your system that might not be allowable, you are opening up yourself to fines and lots of trouble when you go to selling your house.

I highly second the bolded part. I live in a town where many things do not require a permit and even fewer require inspection. But septic work here? You'll need a plan (more than likely from a licensed person), a permit, and inspections along the way.

That is the right way here to deal with changes, reality is the AHJ is one person once a week and with larger lots there isn't much to see just driving by.

Here is my two cents.

Such a new system, absent abuse, should not have failed. Multiple failures in the development seems to point to either a problem with design or installation. After 5 years and a change in ownership, I would be surprised if you have any recourse against the builder/designer/installer. As suggested getting the plans from the AHJ isn't a bad idea.

If terralifting actually happened a year ago and needs to be done again, I would not have much confidence that a second round will be successful.

All of the work you ask about seems like re-engineering the existing field on the fly. And without identifying the cause of the problem I would not be inclined to reuse most existing materials, that might change depending on what type of system it is.

I would call out an engineer, not a septic company (here there are independent engineers and you can then bid out their design). In my experience they'll look at existing soil conditions and design a system for well less than a grand -though it has been about 10 years since I hired one-.

Here land is somewhat plentiful and the prepared option for a failed leach field is abandonment in place and replacement if a new location. IIRC that is in part because removed leach field soils have to be disposed of in certain manners.