new region, few options, questions, comments

[sam74]

So I am in the process of learning how things work in a region new to me 60 miles south of Canadian border in the Plains (I'm from the SE). Sanitary waste disposal seems to be a large problem with little municipal sewage collection and treatment due to the fact that cities or heavily populated areas are few and far between. Low soil percolation rates for onsite treatment seem to be the norm. For a single family home that may not be an issue but for larger facilities a drainfield and 100% reserve area can consume more than half the developable property. That leaves a few options including store, pump, and haul systems or a decentralized WWTP followed by a wastewater stabilization pond per local regulations. They also allow underground injection of wastewater with a class 1 injection well permit but no one seems to be doing this (any comments on this method are welcome).

The local requirements for effluent discharge into a wastewater stabilization pond following WWTP vary according to setbacks from existing residences. 1/4 mile set backs have the requirement of a BOD5 levels at 25 mg/l and a TSS levels at 30 mg/l. 200 foot setbacks are allowed with effluent levels of BOD5 at 10 mg/l and a TSS at 10 mg/l.

The stabilization pond is required to have a volume of 180 days storage so during winter months when the receiving waters are frozen there is no discharge as the outlet pipe is valved off. There are other storage volume options with well documented wastewater reuse plans.

During warm months the valve is normally closed but a discharge is allowed every 7-10 days. The outlet pipe is 6 to 8 inches off the bottom of the pond so a shallow pool of effluent will always remain. What provisions can be taken to ensure that the pond inlet pipe does not freeze when there is a transition between warm and cold months and your water elevation may not be very deep?

 

[tkall]

Sam:
Working in cold country poses significant challenges that have the potential to become major problems if you do not account for the effects of the cold in the design. I have been designing onsite wastewater systems in the Rocky Mountain region for years and am still surprised by the effects of minus 50 temps. Drainfields are really the best choice for disposal because they can be protected from the extreme cold. The key is to utilize a higher loading rate by providing treatment. The link is to a magazine article highlighting a system we designed in Fairview Montana, not far from the Canadian border. It may give you some ideas.

http://www.onsiteinstaller.com/editorial/2013/05/setting_up_camp

 

[sam74]

Tkall,

Thanks for the good read. I'm not too far from Fairview. However, across the state border the regulators don't allow drainfield size reductions for any reason at this point. Has there been much research and documentation to reflect the higher loading rate associated with secondary treatment discharge to a drainfield?

I hear there are a lot of failing septic systems currently. Of course I'm sure more than a few projects similar to the one mentioned in the article were built not according to plans or not approved by the state. There is a lot of building going on prior to plan approval.

32 minutes per inch loading rate mentioned in the article isn't that bad. I've seen several 100+ minutes per inch in the last year.

Do you offer consulting services as the EOR for the secondary treatment systems? We have been searching for resources such as that and might could add you to the list.

 

[tkall]

Sam:
We will generally work with the owners engineer by providing design and construction services. In the article, we actually helped the owners engineer design the whole system and asssited the contractor during construction. We are pretty flexible and willing to work in a variety of capacities.

There is a good body of info related to increased hydraulic loading based on soil acceptance rate and treatment prior to discharge. We have utilized a variety of tesst depending on the project size, for instance a basin flooding test may be in order if you really want to quantify the clear water acceptance rate of the soil. I generally recommend pressurized systems because they will maintain unsaturated soil conditions and will increase the life of a drainfield. If you are in ND, I know they are working with our Montana regulators to try to get a handle on the boom they are experiencing. I can provide you with some references if you want.

We just finished up two RV parks near Sidney Montana are working on several highway rest area systems. Very high strength waste at these facilities.

 

[sam74]

tkall,

Yes I'm in ND. Any references you can provide without too much effort would be appreciated. It has been an education since I've been here with the lack of municipality provided water and sewer services in the vast rural areas. That is not exactly what I am used to.

When I first arrived we were proposing mostly all pressurized zoned chamber septic systems. However the State would not allow a size reduction for this method. So even though it is a much better delivery system it was costlier to install than the conventional gravity systems.

We recently found another inventor of a secondary treatment system who will design and seal based upon project specific needs. The more the better.

 

[tkall]

Sam:
I have some software I have made available for free for designing and analyzing pressurized systems. It is at

http://www.squirtonsite.com

I think you will find it helpful. If we can help with your projects we would love to. If you send me an email (I think the article has my contact info) I will put you in touch with the Montana distributor. He and I have been business partners for years and we ran a very successful consulting engineering firm out of Bozeman. Now our focus is on onsite wastewater treatment and we have become the most popular system in Montana.