Septic Systems 1

[madenmt]

I was wondering if anyone out there knew of a septic system for a floodplain. We live in one of the driest (sp) county in Montana, my husband's family has owned this property for over 60 years and never have we had a flood, but are still considered in the floodplain. We have spent a fortune to buy a liquor license to go with the bar and motel we want to build,there is actually a sewer permit for a shop on our property, but now they say we are in the floodplain and need a more modern septic system. HELP!















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[GoldDredger]

There are alot of variables and unknows. My advise is to hire a local civil engineer to look into it for you.

First off the floodplain would be determined by FEMA maps, I would want to know exactly where that boundary is. (You'll have to know that to set the motel finished floor elevation anyway).

Second, a septic system (leachfield) for an entire hotel would be pretty large. How far away is public sanitary sewer?

Last, who are 'they'? Is it the county, city? When they say you need a more 'modern' sewer system, do they mean for the hotel or for the existing shop? They should at least tell you specifically what they want...not that they want 'a more modern one' and let you figure that out for them.

Anyway, hire a local engineer and make your life easier.

 

[cvg]

I agree that the county should be forthcoming on what their requirements are. Sit down with them and ask what exactly they want and for examples. This meeting should probably be with a county engineer, not with the guy at the counter...

 

[daddymem]

First off, good advice going to the local guys and see what the requirements are.

Around here we can build septic systems in the flood zone. We just have to compensate for any flood storage filled in if we have to mound. Nothing special about the systems though. If it were my system in a flood zone I would look at concrete flow diffusers and hope they stay put in the event of a flood. If your septic system is washed away in a flood, it is probably low on your list of worries anyways.

 

[civilperson]

Mounded lateral system can put the drainage invert above the flood elevation.

 

[cedarbluffranch]

Did you ever find a solution to your septic issues?

 

[Rob2004]

Check FEMA maps to determine the Finish Floor Elevation. You may have to fill the site with import material.
Instead of a deep septic system, you could have a wide/shallow septic system, and have a network of perforated pipes to discharge the effluent from the septic tank for percolation (something like a stepped construction).

 

[oldestguy]

In our town we found that who ever mapped the flood plain was off by about 50 feet vertically. You can see a lot of mistakes are possible with this aspects.

I'd check that out first and find out what basis they used. In our area it is the State DNR that determines this, not FEMA. They may have some old data, but if you can't get that district limit moved, here is what is required here for flood plain.

The disposal field is no different than the higher ground type, but the septic tank has to be what they call "flood proof". This means the lid has to be bolted down and the whole tank has to be anchored so that it won't float as a empty container.

A geotechnical engineer, along with the civil engineer can solve these problems.