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Landscaping & Design/Drainage - Hydrostatic pressure


3 times in the last 20 years my basement has flooded due to extremely heavy rain.  The sump pump could not keep pace with the rising water under the floor and hydrostatic pressure through the cinder block walls.

A waterproof contractor has suggested a deeper and more powerful sump pump, and french drains inside the basement.  It doesn't make sense to me to allow the water to enter the basement and then remove the water.  

The problem occurs because my backyard and 3 of my neighbor's yards all slope down away from our houses into a low circular area approximately 30' diameter on my property.  It is like a dry "pond", 5'-8' deep if completely full.  

Every spring water accumulates about 1 foot deep for a few days, but rarely any other time.  The good news is it provides natural collection of water runoff away from the house.  The bad news is that the horizontal hydrostatic pressure of 3-4 feet of water during these torrential storms combined with a high water table and saturated soil results in flooding.

I am thinking of installing a drywell outside the house, with a submersible pump to pump the collected water to the front yard, away from the house where it will drain away without problems.

Does this make sense?  To put my drainage in perspective, my neighbors all have sump pumps that run every 10 minutes, 24/7.


Drywells could be part of the solution but you will also need devices to direct the water away from your house and if that cannot adequately address the problem you may need to combine that with drainage devices in your basement. I would focus on using the circular area as a detention basin if you can find an adequate outfall for its water. Think about installing drain pipe under the water table.

The main objective in this case would be to lower the water table and that can be done with drain pipes underneath it or with special dewatering wells or with a dewatering trench. You may need a permit for a detention basin.

Mark Harshman

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Design of landscape structures and design of planting arrangements in the landscape. I usually do not answer questions of a horticultural nature or about growing plants or gardening unless they are related to design. I will answer these questions at my discretion. I will answer maintenance questions at my discretion,usually when they are related to design. I am a landscape designer. I am not a contractor or a gardener. Although I will describe how something is built I do not provide detailed installation or construction instructions. Here are example categories of problems I can help you with: Design of residential walks,low walls,low retaining walls,fences,drainage systems,arbors,plant selection,xeriscapes (low water use landscapes),rain garden design,rain water harvesting,permeable paving,sustainable drainage. No advise on an architectural or engineering level. I DO NOT PERFORM ACTUAL DESIGN WORK THROUGH THIS SITE. I only provide suggestions and advice. For more comprehensive help check out my website at:


Landscape concept plan for a 30,000 square feet housing site. Involved site recon by pace measurements and photographs and a site analysis and a site analysis report and recommendations and a preliminary cost estimate. Design elements included canopy trees,shrub cover,accent flowers,trash receptacles,benches and planters. Landscape concept plan for a 7,000 square feet site for a community center. Involved site recon by tape measurements and photographs,a site analysis and the creation of 3 conceptual designs for the site. Work was done through a local professional design center. Design elements included tree garden,playground,sitting area,lawn,cooking area,lighting and concrete and brick paving. Landscape concept plan for a 3,000 square feet housing site. Involved site recon by tape measurements and photographs and a site analysis. Concluded in 3 concept designs for the site,shown at a formal presentation,a site analysis and recommendations. Work was done through a community volunteer program. Design elements included decks,a playground and fencing. Briefly as draftsman for landscape designer/gardener. Conceptual landscape design for residence. Involved site recon by tape and pace measurements and site analysis. Design included covered patio area,ground cover and flower beds. Two years experience as draftsman for transportation department in engineering firm and for engineering consultants to phone company. Duties consisted of plotting topography. Survey crew member. General assistant to surveyor. Work was done for U.S. Army and County Highway Department. No instrument work. Duties included tape measurement,holding graduated survey rod and plumb bob for sighting and clearing brush. Marketed Landscape Design Services. Brochure writing,promotional material and marketing graphics.

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From Civil Engineer: I am very impressed with your work and with the obvious thought you have put into the marketing of your venture. It was especially good to see a print of that job we discussed on the phone. I wish you much luck with the venture as I do with your plans for school. Im darn proud of you buddy. And by the way,when I get my license,maybe you will consider me for a consulting job down the road. I hope to get together with Rick sometime soon and I would really like to show him your stuff if its ok with you. From all these questions you ask I get the feeling that you are genuinely interested and have put alot of thought into the idea and process of landscape architecture and if you could possibly afford the cost I would urge you to take some classes in the areas you are most interested in. The subject is not so simple as it appears,mixing science and engineering with art and a certain amount of religion to create a comfortable and pleasing balance between man and nature. A thoughtful soul like yours can do this but it can be a lifes work getting it right.

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