Question
QUESTION: My house sits on about an acre.  Behind my house is a wheat field (not being used now) that is higher than my yard.  When we get lots of rain, it floods my yard.  I was told to put berms in and did but the water seems to seep underground into my yard.  My biggest problem is that I have a septic tank and lines in the back yard and the water flood them--making my housing plumbing unusable.  Two years ago my house looked like it was sitting in a lake.  With the berms, most of the water has be rerouted but still my back yard floods.  Any suggestions?

ANSWER: Hello,

You need to install drainage ditches.  You should have a peculation test (test to measure at what rate water soaks into the soil) done, to help determine the size and type of drainage system.  You may need subsurface drainage (perforated drainage pipe) in addition to drainage ditches.
A perculation test should be standard procedure when installing a septic system.   Plant vegetation on the sides of the drainage ditches to control erosion.  Good luck.  Write back if you have further questions.


Mark  Harshman
http://www.harshmandrafting.com





---------- FOLLOW-UP ----------

QUESTION: Tell me about the drainage pipes that you are recommending.  Do they have a grate on the top?  Should they run from the middle of the yard to the sides where the ditches are?

ANSWER: Hello,

The perforated drainage pipe has holes on one side. The pipe is layed so that the holes are facing the bottom of the trench the pipe is layed in,to prevent soil from leaching into the pipe from above.

The pipe can be simply backfilled with soil or layed in a gravel filled trench. There is no grate over the pipes because the pipes are buried out of sight.

The pipes should run parallel to the drainage ditches. The purpose of the pipes is to catch water that gets past the ditches and act as a backup to the ditches. The pipes should be placed on the sides of the ditches.
Good luck.  Write back if you have further questions.

Mark Harshman
http://www.harshmandrafting.com
http://www.dagur.us/guru/markdraft
http://www.liveperson.com/markland
Email: [email protected]




---------- FOLLOW-UP ----------

QUESTION: I am not sure how to put the drainage ditch to the side of the yard.  I had berms put at the back of the back yard and the west side of the back yard.  They helped a lot.  He did not put the berms on the east side of the back yard because of the electric and gas lines there.  He made the berms from the dirt on the side of the yard so that it is a shallow ditch on the far side of the berm.  If I understand you correctly you would have me dig a trench and place perforated pipes in the trench and cover them with dirt.  

I suspect that the apple tree in the back yard causes underground water to enter my back yard.  I have seen little fountains of water spurting up during heavy rains.  

Also, the latteral lines in the back yard have a lower level of dirt between the lines.  I wonder if I should have dirt hauled in to make the area between the latteral lines flat.

Answer
Hello,

The pipes would be one way to increase the effectiveness of the drainage ditches. They should only be placed if needed. If water seeping through the bottom of the ditches becomes a problem,then drainage pipes could be used to channel that water away. The pipes will catch water not taken care of by the ditches. Lining the ditches with plastic or fabric will also aid in preventing infiltration into the soil.

Filling in areas where water is pooling may or may not be a solution. The entire site should be analyzed by someone knowledgeable in drainage and then an appropriate design chosen. Since I have no such analysis of your site I can only offer general suggestions. Bringing in soil can be very expensive. If you dig ditches,perhaps the soil from that could be used.

The berms may be trapping water behind them. This water may be seeping under the berms and leading to soggy conditions on your property. The water must either be channeled away or allowed to seep into the ground or a combination of both. Placing a retention area behind the berms could be a solution. This is a temporary holding area for water composed of porous soil,mulch or gravel. The water seeps down to a low enough level so as not to cause any problems on the surface. Another solution could be a floodwall. This is a wall constructed of concrete or masonry placed at a certain depth underground,the sides of which form a pool for the water. A flood wall is similar in structure to a retaining wall and is cantilevered (has a T-shaped shelf portion on which the weight of the soil rests).

The flood situation you described around the tree may suggest an impervious layer below that is trapping water above it. This could be a layer of clay or rock. Or perhaps the ground is just saturated from water flowing down the slope.

The drainage ditches should be placed on the old wheat field slope. Depending on the flow volume and the shape of the slope,you may want to install swales instead of ditches. Swales are more shallow and wider. The idea is to intercept water flowing down the slope and remove it to an area away from where your property floods. Good luck. Let me know if I can be of further help.

Mark Harshman
http://www.mahdrafting.com
Email: [email protected]

http://www.allexperts.com/ep/724-104627/Landscaping-Design/Mark.htm