I've got a question I need help with. I want to build some raised vegetable beds but where I want to build them is over my septic system leach field. The pipes are buried three feet under ground. I plan to build them out of cinder blocks and not dig into the ground. Any opinions or advice would a great help. Thanks in advance.
Haven't been to Coushata in a long time, tho I do go by there on the interstate ,My question about this is how low is the area and do you get some flooding during heavy rains .Next question are you planning one block high or two if the answer is two then the flooding question is moot. Now my only comment is to not make them too wide ...Talked to my Nephew last evening and he is moaning about the hot dry weather BTW he lives in Rapides Parish..Good Luck
I agree with "not too wide". On big advantage of RBs is that you don't walk on the soil. So make sure that you have access from both sides of the bed. Also, I'd urge you to keep it under 3 feet wide. It is a lot less work if you can weed, prune or pick by just reaching accross, without walking all the way around each time you spot a weed..
I have trouble stooping or even bending, so I love the way a RAISED bed brin gs the soil up to me. I even dig sunken pathways around my beds, which makes their drainage even better, their root zones deeper, and my back and knees happier.
The walls can sit on soil at the current grade.
The wlakways can be dug 6-12 inches below garde.
The walls can be raised 12-18" above grade.
And the topsoil dug out of the walkways can be thrown up on top of the bed.,
There are some safety concerns regarding bacterial contamination with planting over septic lines. I suspect they are overblown, but you are basically talking about putting greywater in your garden. Lots of people do greywater deliberately either as a way of reducing water/energy consumption or because it's good fertilizer. I wouldn't be adverse to it, provided it was MY greywater. I'm not so sure about eating out of someone else's toilet, tho. :)
More of concern is the stability of the field itself and what happens if the field needs to be worked on. If you are going to invest a lot of time and money and energy into building great soil it would be no fun to tear up your garden for the sake of working on your septic field. Shading the field with too much vegetation, adding extra soil on top of the field and watering and fertilizing will reduce it's efficiency. If there is one or two people in the house, that's one thing, but if you have 6 people in a 3 bedroom you might overload the field.
If it were my land, I would build somewhere else if possible, but it it were the only spot I would stick with shallow-rooted veggies and avoid carrots, beets and other plants which have vigorous and deep root systems. I'd also include wide walkways to help the field dry out properly. (Which I'd recommend anyway. Being able to easily get a cart or wheelbarrow between the beds is very handy.)
True 'greywater' is not from the commode, rather only from the sinks, baths and washer. This being a leach field probably has the overflow from the septic system (commode) feeding into it also.
For some understanding of your leach field, is the top soil in that area moist only occasionally, often or not at all?
In my limited raised bed experience if it is not moist, I do not believe the moisture will wick up into the bed. On the other hand you need to be careful not to impact your own field lines. This added weight, soil and traffic may interfere with proper drainage.
Currently with six raised beds here, I would not encourage you to dig into the soil under the beds.
I would contact somebody in your area that installs or maybe inspects septic systems, See if yours is good for another 10-20 years, AND ask about putting anything on top of the leach field. I was under the impression that you could not change the grade over a correctly installed leach field - that you aren't supposed to raise it or lower it. Also, I was under the impression that if something went wrong with the system, that replacing the tank is less expensive than replacing the field - so you don't want to mess up your field.
I looked into what you can plant over a leach field several years ago. No woody plants, of course, - but with herbaceous plants, the recommendation was for plants that grow in wet weather and go dormant in dry weather - that way the plants help keep the leach field from getting over-saturated. Weeds fit this description, grass is the usual choice, bulbs are used sometimes.
I had trouble finding information on this subject when I looked into it a few years ago. If anyone else has better info on Landscaping/Gardening and Septic Systems, I'd like to hear it, too.
Good information as usual Pollengarden. I suspect that Colorado is more heavily regulated the Louisiana is ( or TX for that matter ). Anyway, the planting information you found sounds applicable to inground planting. Raised vegie beds should not be as intrusive on the field lines.
And getting the system serviced before anything is done is a good suggestion also. That is assuming there is a septic tank?
I remember something about a leach field being a balanced living ecosystem. I think the surface needs to "breathe". I was thinking the extra soil would add weight that would compact soil next to the leach field interfering with the existing movement of water & air. Or cut off the air if it does need to breath. But I am on sewer, don't have septic, and really think you should get some info from somebody who does know septic systems.
Here in Colorado, we have something called "engineered" systems. If the soil isn't the right kind for septic systems (tight or heavy clay?) - they excavate the area and back-fill with soil that is better for a leach field (pea gravel? Silt?). They are usually shaped like a pillow, with half below grade and half above.
One mistake people make with leach fields here is that they don't plant over them, then forget why it is the only open area in the back yard. Then they drive a heavy truck over it - a cement truck for instance. Or the utility company taking a shortcut. That can crush and break things under ground you don't want crushed and broken. So I guess having raised beds would keep anybody from driving around on it.
pollengarden, the engineered systems in this area are typically sand mound systems -- they build up out of sand and then the pipes are close to the surface and drain down. You absolutely do not plant over those since extra organic material will make them fail, but they are also hard to forget since they are literally a big mound. I had one at my old house; the site didn't perk fast enough for a traditional system.
I just had an idea. What do you all think of using large tree pots instead of buildind raised beds? I have about 70 15,25,35 and 45 gallon tree pots that I can use. The reason I wanted to build my raised beds over my leach field was it is the only flat ground that I have. The pipes are buried about three feet to two feet deep and are the type that have shipping peanuts around them in a sock. My septic tank is 750 gallon and I only use about 1000 gallons of water a month. I have grass growing over it and the grass really grows fast. The soil is very sandy and even after a six inch rain it is not muddy. If I use pots I could move them if I have to work done on the system. Do you all think that it is a good idea to use pots?
A 750 gallon tank is pretty small; I don't think they make them under 1000 any more. If you system is older, I would definitely have it pumped and inspected before changing anything.
Pots would certainly resolve some of the issues, and if you see signs of the water backing up in your house or seepage issues in the yard, you can just move the pots. But flat land isn't necessary to garden on if you have raised beds. My garden is on a slope and I use the beds to terrace it and make flat spots for growing. My walkways bear the brunt of a lot of the slope, too. Overall it's about a 10% grade but this would work if it were even steeper.
Those are some nice beds. Do the deer give you problems? My tank is only 14 months old. It is the size that the county said I had to put down. Where I work at we sale 350(Not really a septic tank but a grease trap), 500, 750, 900 and 1000 gallon tanks. What size your house is and how many bathrooms it has determines what size tank you have to put down according to LA rules. I have three eighty foot runs of field line and they were installed very carefully with the grade shot for all eighteen joints of pipe. I was very impressed. So far so good.
Wow. Minimum size permitted in this area is 1000 for a 3 bedroom, and no one builds anything under that size around here.
I don't have deer, although I don't know why since I have everything else and there are certainly deer nearby. My big problem is rabbits -- the fence has been rabbit-proofed -- but lately some extra owls have moved in and I am not seeing many rabbits anymore.
I live in a 16x60 custom mobil home that I ordered with extra insulation. It is very energy efficent and snug in summer and winter. My november electric bill was thirtynine dollars. The deer where I live eat everything. At my old place they even went inside my greenhouse and under my carport to eat plants in pots.
A lot of good info for you to mull over I grow a lot of plants in the pots, for whatever reason peppers seem very adept at growing in pots as do many veggies the thing I like best about growing in the pots is if I don't like how a plant is growing in a spot I just use my hand truck and move it ..Just a word here on the moving I always mark the north side and keep that always oriented to the north just as it was to start with ..Don't know if that helps but that rule was told to me by a very wise old gardener some 30 odd years ago ..He was talking about moving trees and shrubs and I did notice that it did seem to work out so I just kept up the pratice...Should add that it is best to make sure they dry out real good before attempting the move water is very heavy..Been a long time since I have been to Coushatta but I do know that you have growing conditions there that do no exist anywhere else in the USA Good Luck