Replies

1. 
   johnnyd | Sep 10, 2003 09:30pm | #1

   I got alot of help from a civil engineer in my neck of the woods, who ultimately did the design work as part of a request for a zoning variance.  Counties can be pretty picky about percolation tests, distance between grade and bedrock, etc., and it's those things that quite often dictate what kind of drainfield/septic system you'll need.

   Are you getting a permit to construct a drainfield, just filling in the form, or just curious?  I'll post some links to information I found last year.

   This one is pretty good, but somewhat limited:

   http://www.extension.umn.edu/distribution/naturalresources/DD6583.html

   
   

   ---

   Edited 9/10/2003 2:32:51 PM ET by johnnyd

1. 
   goldhiller | Sep 10, 2003 09:50pm | #2

   Here's a bit more. Might be helpful. I've got a book on this all but that would be kinda hard to post. :-)

   Gotta run for now. Lunch has been briskly swallered.

   http://www.metrokc.gov/health/wastewater/types.htm

   Oooops. Meant for CH.

   Knowledge is power, but only if applied in a timely fashion.

   Edited 9/10/2003 4:40:51 PM ET by GOLDHILLER

2. 
   DavidThomas | Sep 10, 2003 10:00pm | #3

   Jim:  They differ mainly in cross-section  i.e. the shape of the interface between highly permeably fill and lower permeability native soils.  The worse the results of a perc test, the larger an area the interface needs to be.   

   The other driver is the depth of the water table.   With very shallow water, you end up having to do a mound system where all the percolation AND treatment occurs in the mound.  That is a mess of dirt!

   So you need 1) enough surface area to perc the design flow rate and 2) enough unsaturated soil to allow microbes to breakdown the effluent from the septic tank.  Getting that 1) surface area and 2) volume is why different geometries are used in different soil types and with different water table depths.

   I'll try to look up all those terms when I get home.  My own house is on such clean sand (below the brown dirt) that the perc test dictate only 21 feet of leach field.  At an 11-foot depth for freeze-protect reasons, but otherwise a very easy area for leach fields.

   David Thomas   Overlooking Cook Inlet in Kenai, Alaska
3. 
   SamT | Sep 10, 2003 10:30pm | #4

   I just had to do the research on this myself and I will share with you. But no one else, so, keep this to yourself, OK?

   All Septic System Information Website
   Columbia Homeownerrs Guide to Lagoons
   Household Wastewater Management
   Lagoon Design & Operation
   NSFC Onsite Wastewater Regulatory Agencies by State
   Onsite Edition 13
   Residential On-site Wastewater Treatment Lagoon Design and Construction

   If you want, I can send you my entire "septics" library. It zips to only 8MB. ;>)

   SamT

   "You will do me the justice to remember that I have always strenuously supported the right of every man to his opinion, however different that opinion may be to mine. He who denies to another this right, makes a slave of himself to his present opinion, because he precludes himself the right of changing it."   Thomas Paine

1. 
   CloudHidden | Sep 10, 2003 11:30pm | #5

   I'd been to a lot of these sites, but they don't use some of the same terms as the form. It's a FL form for a client and he has a permit for "filled" and "bed" but not the others. So I'm trying to learn more about the distinctions. I only design w/in the building envelope with just a waste pipe out of the house, but I still do want to learn about this other stuff.

4. 
   Danusan11 | Sep 11, 2003 02:02am | #6

   Have had some experience with septics, for what it is worth this is what I know. Standard and trench to me are the same thing, generally 3' trench (width) depth is usually determined by the county sanitarian or civil eng., which usually occurs with perk test.  All fields size and type are determined by soil conditions and number of bedrooms.

                                           

   Filled indicates to me that material is excavated out and a washed  course sand (2ns) my geo. area is installed, again depth of cut is then determined  by civil eng. or sanitarian.

    

   Bed is usually area excavated with stone and or sand thru -out as opposed to trench system, in some instances I have done a 50% percent cut down which is half of area excavated to 8-10' and filled with sand and then stone .

    

   Mound can be a combination of the ones mentioned above,(exception trench) with area contain by clay berms to prevent leaching from sides. Mounds are generally 2-4' above existing grade., always depending upon civil eng. or sanitarian requirements.

    

   Sand filter systems are the new thing where soils will not perk, fairly extensive and pricey, but doable, Oregon and Florida have used these systems a lot, might find some info on these by doing search. If this is a possible option I can provides you with a little more info.  Concerning their installation and general working principle, these systems have to designed by civil eng. In my area 30" max. fill above drain tiles so system can still breath Hope this helps a little  for your general knowledge.

5. 
   bikeralan | Sep 11, 2003 02:25am | #7

   Look at http://www.orenco.com, they have a lot of residential systems, I run a wastewater treatment plant, we use their products, good reliable equipment.

   usual disclaimers apply

   Alan