SOIL CONDITIONING TO PROMOTE WATER RUNOFF
Can you tell me if there are soil additives to PROMOTE/INCREASE water runoff? I'm looking for alternatives to installation of French Drain on the back of my house. My roof is pitched to sides of house, so gutter overflow is not the problem. I have increased the drain slope, but I can not maintain grass along back wall which is in full shade. Thank you.
We would encourage you to consider a system that would enhance water infiltration rather than runoff. It sounds like a rain garden would be an option for you. It would catch and hold water temporarily and allow it to infiltrate into the ground slowly at the base of your drain slope. Rain gardens reduce erosion and help to recharge groundwater. Take a look at the following publication for an introduction to rain gardens: https://extension.umd.edu/sites/extension.umd.edu/files/_docs/RainGardenFactSheet_0371.pdf#overlay-c...
A more comprehensive guide to planning a rain garden is available here: http://extension.umd.edu/sites/extension.umd.edu/files/_docs/articles/Rain_Gardens_Across_MD.pdf
Plants for shade (a variety of herbaceous perennials) can be included. Once it is set up, a rain garden does not require more maintenance than any other type of garden.
You ignored my question. I agree that a rain garden is a nice solution, but it is one that entails more work and expense than we are currently able to invest in that type of project.
Are you able to answer my original question?
We know of no product that would decrease the permeability of soil.
It is true that clay soil absorbs water more slowly than sandy soil or loam. Once clay gets wet, however, it holds onto moisture longer.
Since we don't know what your ultimate goal is here (a drier basement?), we're not sure what would be helpful. If you're trying to block rain from being absorbed near the foundation, perhaps one or two rows of pavers laid along the foundation, tipped away from the foundations, would fit the bill. It would block absorption and divert rain.