septic field frozen

[DFB]

Well were supposed to easily have 4 ft frost depths around here that's why building footings by code are 60". Under the plowed roads its been said the frost has run a full 6 foot deep this year caused a lot of water main breaks because that's deeper than the average pipe installations

My system has less than 24" of ground cover plus only snow cover hasn't ever been frozen as far as I know

Granted it not as cold here as the OP has stated his conditions are but there was very few days above freezing and temps were steadily at zero or below for extended periods again this winter.

Now at least three times here the draining of the delivery lines has been mentioned as a possible cause. My system has the same drain hole in the pump line connection but it does only drain back the delivery lines the actual bed pipes are level and were set with no pitch back so whatever fluid is in the pipe has to drain on it own. My drain bed does sit at least 4 feet higher than my the top of my tank and the pump sits another 5 ft down inside the tank. So I have a good 9 ft of delivery head at least maybe over that and I seen much more

If I read his description correct the drain pipe is only 1 1/4" dia. with 1/8" weep holes. After pressure feed and drain back how efficiently that would continue to drain the effluent left in the pipes is questionable at best. If I remember right I had to drill my 3/8" drain holes one every foot over the 40 ft lateral.

Installing rigid foam insulation could only help against freezing but also increasing the drainage time of the laterals with some larger hole might help too :confused3:

 

[tcartwri]

I think RM is the Regional Municipality or local Health Department.
A new properly designed system should not freeze in use. Something is very wrong both in the design and the construction.

I don't think you appreciate how cold it gets in Manitoba in the winter.. It's -20C or worse every night for 2 months at least. And then in March it flips almost overnight to +30C.

 

[v8only]

My system has the same drain hole in the pump line connection but it will only drain back the delivery lines, the actual field pipes are sloped back towards the end of the field where in theory whatever fluid is in the pipe has to drain on it own, IF it takes to long it freezes or if the ground around my field is frozen the lines stay full as there is nowhere for the fluid in the lines to go. My field sits at least 2 feet higher than my the top of my tank and the pump sits another 8 ft down inside the tank, the main delivery lines are also 8' into the ground.

 

[PILOON]

"If I read his description correct the drain pipe is only 1 1/4" dia. with 1/8" weep holes. After pressure feed and drain back how efficiently that would continue to drain the effluent left in the pipes is questionable at best. If I remember right I had to drill my 3/8" drain holes one every foot over the 40 ft lateral."

I also saw that and thought I'd misread however PIX seemed to confirm.
Have never see or heard of using 1/14", 3" and 4" factory perforated is the norm around here.

Our product (called BNQ.) has 3/8" holes down both sides spaced about 3" apart at the 4 and 8 o'clock positions.
Typical system for 3 BR is 150' of 3" BNQ* using a 750 gal concrete tank.
The field* is generally 5 rows of 30' of BNQ spaced 3' apart and interconnected at both ends using T's and elbows.
This network of piping is laid perfectly level on a 20 ton bed of 3/4" crushed stone and covered by a second load of crush.
A geotextile fabric is used to cover the field followed by topsoil usually enough to blend in with surrounding landscape.

Recently they added dual entry via 2 T's and a vertical vent to atmosphere.
More common now is to also install a grease trap B4 the tank.

Bi annual pumping is done from the tank 1st compartment with liquids being re-inserted.
(personally I prefer total evacuation as the liquid contains suspended solids which in turn flow into the field and clog the soil thus shortening the life)

* a 'percolation test' is a mandatory part of constructing a field.

 

[Looking4new]

I am going to try and get my sewer sucker guy(new guy this year, the old guy retired) to suck out both halves of the tank. Maybe he will, maybe he wont. Time will tell. I am also going to get him to pump every year.

 

[Hilbilly]

I find it strange that your reputable contractor was not aware of this freezing issue. If he has built these raised mound pressure systems in your area before then he should have been aware of this. The approval authority should also have picked up on this issue during the permitting process. How can professionals that are familiar with the weather conditions in your area not be aware of this issue and the appropriate resolution? I would contact the approval authority and ask them what they suggest, if your contractor is not being helpful.

In any case, with these raised mound systems you do not get as much benefit from the retained heat in the surrounding soil as with a "conventional" gravity system. Therefore you will need more insulation. Look for the weak points in the system, ie what has the least amount of cover and focus on getting more cover over those areas. Is the inspection / cleanout exposed to the surface? If so bury it so that there is not a direct connection from the cold air to your system. I suspect there is very little cover over those black pipe housings too and that would be another area of concern. As someone else already suggested you need to try and retain as much heat form the soil and the effluent as possible. Another thing that works with single pipes (not sure if it would work with a larger area, like your entire field) is to put a poly cover about 6" to 12" above the pipe. This deflects the cold from above, around the pipe. But the best solution is going to be more cover / insulation, with the focus being on the areas that currently have the least amount of cover. Good luck.

 

[Hilbilly]

I find it strange that your reputable contractor was not aware of this freezing issue. If he has built these raised mound pressure systems in your area before then he should have been aware of this. The approval authority should also have picked up on this issue during the permitting process. How can professionals that are familiar with the weather conditions in your area not be aware of this issue and the appropriate resolution? I would contact the approval authority and ask them what they suggest, if your contractor is not being helpful.

In any case, with these raised mound systems you do not get as much benefit from the retained heat in the surrounding soil as with a "conventional" gravity system. Therefore you will need more insulation. Look for the weak points in the system, ie what has the least amount of cover and focus on getting more cover over those areas. Is the inspection / cleanout exposed to the surface? If so bury it so that there is not a direct connection from the cold air to your system. I suspect there is very little cover over those black pipe housings too and that would be another area of concern. As someone else already suggested you need to try and retain as much heat form the soil and the effluent as possible. Another thing that works with single pipes (not sure if it would work with a larger area, like your entire field) is to put a poly cover about 6" to 12" above the pipe. This deflects the cold from above, around the pipe. But the best solution is going to be more cover / insulation, with the focus being on the areas that currently have the least amount of cover. Good luck.

EDIT; you could also contact the professional that designed the system and ask them for a solution. If the design is faulty they are responsible. However if it is a maintenance issue they should be able to help with a resolution. Were you provided with a system operational and maintenance manual. It is mandatory in our area.

 

[v8only]

They are aware of the freezing issue, i have been advised by the septic pump operator that he has not seen so many fields freezing in the past it just seems to be because of the new systems and the professionals are more worried about ground protection from the effluent then freezing protection. My contractor has been helpful but he feels he cannot make any changes to the system as it must comply (which it does) it just means more maintenance for me and i need to find a happy medium on coverage during the winter months. I do not have a system operational and maintenance manual but the contractor did come down a tell me everything i need to do to the system.

Another issue that maybe contributing is I am in the wide open field therefore I get little to no wind shelter, my trees are still all young and provide no shelter. I set up a snow fence on the north side of the field and I have about 18" of snow and on the north side i have no snow but i have the bales set up there. So this might be my issue as i discussed before i just might need more frost protection spread out 4' away from my sand mound.

I am just looking for other options I do not want to set up 90+ bales in the fall and have to store them in the spring, dont get me wrong i have no issue doing the labor i just need to make work a little easier, so i thought keep my 90 bales, add heat trace, add insulation, add shurbs etc.

Any thoughts?

 

[Egon]

Is it recommended to grow grass on the mound?

 

[tcartwri]

Are you allowed to put a layer of styrofoam above the field? I guess that might hinder water filtering down...