This discussion is to clarify some points I made on the appliance forum
http://www.greenbuildingtalk.com/Forums/tabid/53/aff/18/aft/81857/afv/topic/Default.aspx

With regard to chamber systems. I do not normally use these for the reasons mentioned. I have used them and would not rule them out in every circumstance. I would normally use perforated pvc pipe in 3/4" drainage rock. It is impossible for the holes in the pipe to get plugged in a properly functioning system as the only thing going through them is liquids. Bio mat will build up first on the trench surfaces and the rocks and then back up into the pipe such that when you dig up a failed system, the pipe may be full of sludge or bio mat. This is caused by lack of maintenance. If there is sludge in the secondary compartment it will get pumped out to the field. Our systems all have 1/8" filter screens prior to the discharge. If sludge is pumped, it will block the filter triggering a service call. A couple hundred dollars in pumping cost or 5 to 15 grand for a new field. Your choice.

A pressure system uses a pump to discharge the effluent to the field. The effluent is distributed throughout the whole field by pvc pipe with usually 1/8" orifices set at a prescribed distance apart. This way the whole field is used evenly and there is usually little bio mat. The pump can dose the field on demand or on time. Time dose is far superior.

It is almost always good to introduce air to the system. This is how most advanced treatment plants work. Some fouled systems are cleared of bio mat by adding air to the tank, mostly because the air in the tank generates a high growth of good bacteria which eats up most of the bio mat causing organism in the tank. This way there is very little additional load going out to the field so the good bacterial in the field can "catch up" so to speak and break down the existing bio mat. Of course with the high load of good guys in the effluent heading out of the tank to the field, they pitched in and helped their buddies already out there. There is starting to be more anecdotal evidence of this type of field restoration. I have as yet not installed just air into a failed system, but I believe that in many case this could be done.

From an energy saving standpoint, it would be interesting to look at the intermittent (vs full-time) use of air.

Jon - The Singular Green has a minimum requirement of 30 minute each hour but you can increase it to 100%.

FBBP -


Do conventional septic systems and gravity fed leach fields work well or do non-conventional or engineered systems work better?

In regards to the Infiltrator systems. I thought they were supposedly better than the PVC pipe systems but from what you stated, I didn't know about the problems they can create. You mentioned the pump delivery system for the leach field. So with a gravity fed leach field, one doesn't get proper distribution, is that correct?

I was told a 2 compartment concrete septic tank works best. What are your thoughts?

Those septic aerator kits that they sell that drop in an anaerobic tank and create oxygen under water in the first chamber of the septic tank, do those work?

Bear - conventional fields work. Have for years, sort of! The problem is that as they trickle from the tank to the field only as small portion of the field receives the effluent and it receives all the effluent till the bio mat seals up that portion, then the effluent moves on to the next part. If you send 25 to 30% of the expected daily volume to the field in a burst, it will flow over much of the infiltration zone. Then the field has time to digest the materials before the next burst comes. That way the risk of strangling quantities of bio mat is reduced.
The better systems are designed to dose the entire field four to five times a day. This cannot be done with trickle discharge. (We are not allowed to use trickle discharge anyway because the risk of freeze up is to great.) If you don't want to use a pump, at least use a syphon discharge. If using a pump, it can be demand dosed by setting the length of the float tether longer or shorter. If you know the volume per inch of your dose (secondary) chamber, you can set it to discharge 25% of the expected effluent each time. If you use a time dose panel, you have to calculate the head and gallons per minute. Then you set the timer to bring the pump on for however many minutes you need to dispense 25% of the daily volume and then set the hours of off time. The advantage of this is that when the aunts, uncles and cousins come over for the weekend and you exceed the expected daily volume, the pump will just pump what the field was designed for and hold the rest for the next cycle. Sometimes it will catch up over night, other time it will take till Monday or Tuesday to get all caught up. Make sure the dose chamber is 1.5 to 2 time the size of the expected daily volume.

A conventional system should be designed such that there is five feet of good soils between the infiltration zone (where the drainage rock meets the ground (usually about two feet deep) and any limiting layer (clays, rock or water or seasonally saturated soils.) When it is not possible to get that separation you either need to build up the field to get that separation or you need to supply better quality effluent that doesn't need as much treatment. This is where treatment plants come into play. There are now numerous approved plants out there and they all work on the bases of adding air and using suspended growth or attached media filters. The ones that just add air rely one the good (aerobic) bacteria to remain suspended in the effluent to treat the effluent. This works. The better plants use the same air technique but add a bio filter of attached media for the good bugs to grow on. Most often this is just a series of plastic disks or balls that the effluent flows over but because the bacteria is attached it remains in place. This is the same way that fish pond filters work. Plants like this will discharge clear liquids with almost no suspended solids. After a Singulair Green plant has been operating for about a week your eye will not be able to differentiate between a glass of effluent or drinking water.

I am not aware of any jurisdiction that allows single compartment septic tanks. There are still many out there but you would not be allowed to put in a new one.

The drop in kits are suspended growth systems and work much better then a standard tank, somewhat less good then attached media plants.

FBBP,

Thanks for the all the info.

Do you recommend installing a larger leach field than needed and having a bull run valve that one can switch field use every 3-6 months ?

Out here most septic installers prefer the Infiltrator units but they still install the PVC pipes also.

What do you think of installing this SludgeHammer unit in the 1st chamber of the septic tank?

I have a Delta Whitewater Treatment system which has been in place for 8 years now and it is the finest septic system I have ever seen. It has a cone-shaped circulator that the air bubbles travel up which gets a swirling motion going in the tank. I guess it is classified as an aerobic treatment system, but the effluent is crystal clear and sweet, and it appears that the drainfield will last much longer than other systems I have seen. I don't like the fact that it uses a small amount of electricity 24/7 to run the air pump, but I guess that could be solved by adding a solar panel to your array and telling yourself it is balanced out.

Posted By Lbear on 15 Nov 2013 02:26 PM
FBBP,

Thanks for the all the info.

Do you recommend installing a larger leach field than needed and having a bull run valve that one can switch field use every 3-6 months ?

Out here most septic installers prefer the Infiltrator units but they still install the PVC pipes also.

What do you think of installing this SludgeHammer unit in the 1st chamber of the septic tank?

It depends on what it is costing you, what your daily peak volume is and what your tank cost you. It is also debatable which chamber to put it in. I can think of good arguments for each but in the better plants you have a settling or trash tank, then the aeration tank which means the aerator is not in the sludge or floatables.

Posted By ICFHybrid on 15 Nov 2013 06:35 PM
I have a Delta Whitewater Treatment system which has been in place for 8 years now and it is the finest septic system I have ever seen. It has a cone-shaped circulator that the air bubbles travel up which gets a swirling motion going in the tank. I guess it is classified as an aerobic treatment system, but the effluent is crystal clear and sweet, and it appears that the drainfield will last much longer than other systems I have seen. I don't like the fact that it uses a small amount of electricity 24/7 to run the air pump, but I guess that could be solved by adding a solar panel to your array and telling yourself it is balanced out.

White water has been around for a long time and are dependable. Smelling is believing. Most people won't believe effluent out of a plant doesn't stink.

How is your system set up? Is it just the Whitewater or is it a standard tank followed by the Whitewater?
iirc Delta also makes a pod type unit which uses attached growth rather then the suspended growth of the Whitewater. It does a better job of denitrafication.

Posted By FBBP on 15 Nov 2013 11:39 PM


It depends on what it is costing you, what your daily peak volume is and what your tank cost you. It is also debatable which chamber to put it in. I can think of good arguments for each but in the better plants you have a settling or trash tank, then the aeration tank which means the aerator is not in the sludge or floatables.

It is a 2,000 GAL - two chamber - concrete tank with plastic risers on both chambers ($2,700 delivered & installed). The Sludgehammer is supposed to go into the 1st chamber and break up the solids and then the 2nd chamber is the "settling chamber". The other reason why they said to place it in the 1st chamber is to agitate the solids (break them up) and then the 2nd chamber is where the solids would settle. The outlet pipe in the 2nd chamber also has an effluent filter to prevent solids from exiting.

They (septic install company) recommended two leach fields (separated by a bull valve) with 4 lines each at 50' per line.

Bear - I can't believe the prices down there. Do the just give away tanks on the street corners. My price wholesale for a 2000 gallon tank not including delivery is 4498.00

Check out the price of a three compartment tank (put the SH in the middle one) or a Singular Green unit just to see how this compares.

When you stir up the sludge, you create a large amount of suspended solids. These may or may not settle out in the secondary. If you pump, this will not work at all as the pump will put the ss into the field. The ss are smaller then the filter (usually 1/8" ). If you trickle and if the travel distance of the secondary is long enough, much of the ss will settle out. Then what? Maybe the high population of good guys will eat it but more then likely you will have to suck it out.

In most cases the secondary is the shortest distance of the two chambers. Two to three feet. When you dump a bathtub, sink, washing machine etc. the volume of sewage entering the tank pushes an equal volume out. The effluent then goes from the baffle almost straight to the discharge load with ss. Now the field needs to deal with all that garbage. If you disregard the sludgehammer, we normally try to find the tank with the longest distance between the inlet and the outlet. This allows solids to settle and clearer effluent to be forced into the next stage. I suspect dropping a SH into the secondary may well contribute to clearing an already clogged field but dropping one into the primary might make things worse.

Posted By FBBP on 16 Nov 2013 01:07 AM
Bear - I can't believe the prices down there. Do the just give away tanks on the street corners. My price wholesale for a 2000 gallon tank not including delivery is 4498.00

Check out the price of a three compartment tank (put the SH in the middle one) or a Singular Green unit just to see how this compares.

To view the tank dimensions, just click this link Yavapai Precast Tanks
The 2,000 GAL tank is taller than the 2,500 GAL tank which is longer.

From what you stated, it looks like the 2,500 GAL tank is the better option since it has a longer distance from chamber separation.

2nd Chamber separation distance:
2,500 GAL = 74"
2,000 GAL = 49"

The 2,500 GAL tank is $3,500 delivered.

Things up in Canada are always pricier than down here. Septic tanks are common out here.

I can get away by code with a 1,000 GAL tank but the price difference is so minimal that a 2,000 GAL is "cheap insurance" in case we have larger loads (family, guests, etc).

The one issue with a Norweco Singular Green is that the tanks are plastic and I've heard that they can crack over time.

Which tank would you go with?
So DON'T use the SH?

Is it just the Whitewater or is it a standard tank followed by the Whitewater?

The Whitewater is the 3rd tank. Trash tank followed by secondary treatment and then the Whitewater.

Boy, septic systems have apparently become complicated since I had mine installed in 1994. I've got a single chamber 1000 gallon concrete tank and 300' of perforated pipe lateral lines in gravel. The entire system cost $1800 installed. The only thing I've done to it since then is I had it pumped out ~7 years ago at a cost of $100. The guy pumping the tank said it was about 1/3 full of solids at that time which was after it had been in service ~12 years.

It's all about coliform count and whether your ground "percs" or not. You can't doit the old-fashioned way when your perc tests show 10" and the road ditches go 600 meters down to some of the largest commercial oyster beds in the states.

Bear - the 2000 should be fine. We typically use a 2000 for a 5 bedroom home. Primary tank size is based on peak daily volume plus 88 gallon per person for sludge allowance.
Number of persons (occupant load) is based on number of bedrooms times 1.5 persons.
Peak daily volume is based number of persons time 75 gallons per person. (all are Full sized (imperial) gallons)
Bigger tanks equal longer retention time. Long retention time allows more ss to drop out equals cleaner effluent going to the field.

Concrete guys will always say "plastic cracks" and some did. Norweco won't.
Plastic guys always say "sewer gasses erode concrete tanks" and it does. Varies greatly from install to install.

I would use the Norweco but there is nothing wrong with the 2000 provide the manufacturer has a good rep.
No, all things being equal, I don't think I would use the SH, but I would love to try one in the secondary of a failed system.

ICFHybrid - coliform is of course the attention grabber but there is much more to it. But basically you are right, it's no longer about disposal but about treatment.

We are no longer allowed to use just a perk test. We need to do a full site evaluation to check for anything that the septic could cause problems for (water sources etc.) and anything that could cause problems for the septic. That includes digging two 9' deep test pits and logging the soil horizons, checking for restrictive layers, seasonal saturation or ground water levels.

We take a sample of the most restrictive soils and send them to a lab to determine the soils texture by percentage. The soils texture tells us the allowable loading rate (gallons/per square foot) which you multiply by the peak daily volume to determine the amount of treatment trench you need to instal.

This cost the customer the same amount that Arkie paid for his whole system.

Posted By FBBP on 16 Nov 2013 12:39 PM

Bigger tanks equal longer retention time. Long retention time allows more ss to drop out equals cleaner effluent going to the field.

Concrete guys will always say "plastic cracks" and some did. Norweco won't.
Plastic guys always say "sewer gasses erode concrete tanks" and it does. Varies greatly from install to install.

That's why I chose the larger tank. Bigger tanks offer the longer retention time and in case you have those large gatherings, it's always nice to have the larger capacity.

Is not the "sewer gas" that erodes the concrete tanks, methane? If so, methane is the by-product of anaerobic tanks but putting in oxygen into the tank would create an aerobic tank and therefore eliminate or greatly reduce the methane gas. Am I correct?

Have you considered two separate tanks? One 1000 gallon tank for the sewage from the toilets, kitchen sink, etc., and one 500 to 1000 gallon tank for the grey water from the washing machine, tubs/showers, and bathroom sinks? The bulk of your home waste water is the grey water which needs little if any treatment. You could put a sump pump with float switch in the grey water tank on a 24 hour timer and once per day at say 3:00 am have it pump the effluent into a sub-surface irrigation system for your lawn, trees, shrubs, etc. This also keeps most of the soap and detergents out of your main septic tank which will improve its performance. Search Google for grey water irrigation for more info. This is what I'm doing on my new home.

Bear - methane is certainly present and very deadly, however the gas that is the problem is hydrogen sulphide which when recombined with moisture become hydosulfuric acid. This is the culprit. Both are from anaerobic digestion so yes, aeration helps.

Arkie - the problem with your approach is that many jurisdictions don't allow it.

The reasons are two fold.
First, the grey water stream you mention is not without pathogens, especially if there is youngsters in the house.
Secondly, by removing the grey from the black, the black becomes much hard to digest properly.

You are correct in using "sub-surface" irrigation in that you don't contact the effluent.

A better system is to treat all sewage in an advanced treatment plant and then use the effluent to irrigate. Some jurisdiction won't allow that either but more and more are coming around. As ICFHybrid said, it is crystal clear and sweet smelling. The biggest problem with grey water irrigation system it the stink and clogging of emitter. You have to filter it and clean filters all the time. If you put everything through the plant, you eliminate these problems.

Check with your local authority.