repair a berm

[knappie]

My ten-year-old house is right next to the turnpike, with a berm as a noise barrier. Unfortunately, the berm (because the builder filled it with tree trunks and rocks) has shrunk several feet. I want to build it back up and plant trees along the top to, hopefully, protect better from the sound of traffic.

My backyard is narrow, so there is a limit to how high I can go. My question is this: Does anyone have suggestions about this project? I have no idea how much it will cost. The berm is 80 to 100 feet long and (now) about 4 feet high.

[Randy S]

There are methods of back filling the berm (not my specialty) however if you are trying to increase the noise reduction then I could help you with methods of achieving that based on height and distance.

I think you will need a contractor to help with the rebuilding of the berm.

[whatismisophonia]

Dont know about cost but here are some key points:  Use lots of sand and clay:  you dont want it to settle; both sand and clay are good for soundproofing; and they work well together, especially since youre wanting to plant on it, as the sand will provide drainage for the clay.  As such, be sure you plant something that is dense as well as drought tollerant, like juniper or something.  For people who live up north, the pantings should be evergreen so that they will function to deaden sound all year long.

[whatismisophonia]

i should also mention that for anyone reading this who may be building a berm from scratch:  If it's a big berm, you can get rubble, like broken concrete or bricks to fill the mass brunt of it.  The outer foot at least should be soil.  You might want riverbottom dirt, as for my experience, it is usually heavy in clay+organic nutrients, and shouldnt settle to badly.  Also, make sure to add plenty of mulch over the entire berm to help conserve water, particularly if you have large plants on it, as it is obviously higher up and drains better as such then the rest of the soil.  If you get some dirt that is low in organic nutrients, add humus(manure) rather than compost; compost will settle much more than youd like.  Again, be sure to add sand or gypsum to help keep the soil from becoming too compacted for good plant growth.

[whatismisophonia]

oh, and be sure to tamp down any soil you add while you are building up the berm.  When you are adding rubble, mix dirt in with it so that soil doesnt fall down into the crevices from soil above it, which would cause the berm to settle more.

[whatismisophonia]

something else i forgot to mention; mulch is also a quick easy method for erosion control, aside from helping to immensely conserve water.  Eventually you would want shrubs, and groundcover between the shrubs, but do keep mulch surrounding large trees by at least a couple feet wide, and 4 to 6 inches thick.  If you're not using drought tolerant plants, and you dont live in a rain forest, it will probably be a good idea to run irrigation.  I'm trying to stop myself from writing a book here, but i will say that you should also make sure that you do have a thin layer of 100% humus just underneath the mulch, since when the mulch rots, it will actually use up nitrogen in the process, rather than supplying it.  Plants love humus though; it gives them just about everything they need, which is important because youre planting them in heavy clay soil.  Then again, you could always do a low maintenance rock garden, in which case you could easily go without irrigation   Also, if youre wanting to make an architectual statement:  Forego the trees, make the berm very smooth and plant grass on it; or for color and texture, plant several different varieties of low growing ground cover, and maybe plant flowering azalia or pink knockout roses at the ridge, either in individual trimmed smooth globes or together in a hedge(better for soundproofing).  And dont do the alternating plant thing, that's been done to death, and it doesnt look that good anyway; it's just a crappy way of adding variety while at the same time retaining strong lines, though in reality, it only produces both in a degraded form.  It may have it's moments, but only in the right scenariao, and only when it's well done;  most landscaping i see is like wearing a plaid flannel shirt as a fasion statement.  Well, ive definately rambled a little beyond soundproofing here, but oh well    i already wrote it and i didnt want to delete it.