Removing Stagnent Storm Water Below A Grade

[altor]

Hi. I'm new to the list so I apologize for not knowing accepted process. I hired a contractor that built a footing for a retaining wall that blocked some natural drainage in an city easement. In times of rain or when the adjacent neighbor waters property, the run-off accumulates and will not disperse naturally. The footing cannot be removed nor can the grade be changed to re-establish flow. Are there alternatives like pumping systems to removed the water? I've thought of a sump pump but this is in an area where soil will likely contaminate the mechanism, which would imply there is a reliability concern. Thanks for your help in advance.

 

[cvg]

If you are in a City easement, it can be removed. If somebody complains, they will remove it for you...

Pumps are made that will pass solids, however, it will reduce the expected life of the pump.

 

[gibfrog]

You may have just shot yourself in the foot but not consulting a Civil PE prior to erecting your wall.

You need to allow the drainage to pass through or under the footer. I would suggest going through the footer with a series of 4" minimum pipes, (enough pipes to carry the historic flow for the city required design storm and 8" is a much better minimum size. The bigger the pipe, the less maintenance headaches.) to a gravity outfall on your side. The pipe inlets would need some kind of anti-fouling protection and a minimum slope based upon diameter and 2.5 fps. Another option is to remove the footer and reestablish grade. A third option may be going under the footer with an inverted siphon, but this may be worse than a pump or atleast as bad from a maintenance perspective.
Best of Luck

Clifford H Laubstein
FL PE 58662

 

[RDK]

How big a drainage area are we talking about here?

What are the drainage characteristics? (Pavement or grass? Flat or steep hills?)

What are the rainfall conditions? Intensity, duration and frequency?

Is the water clean or full of debris and other potentially harmful material? (leaves and twigs, chemicals, silt?)

How much water is ponding? (Area covered and depth)

What are the soil conditions? (sand or clay?)

How often does the water pond?

What happens to it now? Does it soak in or evaporate? Does the water ever get to a level where it will overflow the obstruction and start to flow again? Does this flow follow the original channel or take off on a new direction?

These and more questions must be answered before we can start to point you in any specific direction.

There are two main choices. You can get the water around the obstruction or remove the obstruction.

If you cannot remove the obstruction (and why not?) then you have three sub choices. You can pump the water, allow gravity flow or do nothing and let the water soak in or evaporate.

You could try a sump system with a gravel and filter fabric covering. This would lessen the amount of soil entering the pump and be more reliable. For small flows this is quite economical and reliable. ( Dig a hole, line it with filter fabric, place about ½ cu m of rock surrounding a 20 l pail with holes in it and place a small sump pump with float switch in it. Cover the rock with filter fabric and cover the fabric with topsoil and sod. Install electrical and piping as required and to local code. All material should be available at your local building center.)

Can you drill through the footing and place a gravity pipe to get the water past the obstruction? Drop siphons are a real maintenance headache, but have the advantage of working automatically in the event of power failures. (That is of course provided that they are not clogged with debris)

Sometimes doing nothing can be a viable option. If the flows and ponding are minor and infrequent this may work, especially if they will soak in over a short period. If the flows evaporate then be concerned about anything in the water (salts, chemicals like fertilizer, herbicides and pesticides etc.) that do not evaporate and will accumulate.

If you built on an easement the holder of the easement usually has the right to remove the obstruction at your cost.

You want a local civil engineer to look at this and perhaps a lawyer to look at the implications of your blocking the drainage easement.



Rick Kitson MBA P.Eng

Construction Project Management
From conception to completion

http://www.kitsonengineering.com

 

[altor]

Here is some more data on the problem. I had a Civil PE prepare plans and they were approved by the city. The drawings show a retaining wall that facilitated raising of the grade level to my house. Drainage on the property was mitigated by a series of catch basins and directed it to the streetside gutter. All pretty standard and legit stuff. The drawing indicated the wall must be out of the easement, which it is. It's the footing that the contractor built that encroaches 8 inches into the easement. The field inspector approved the foundation before concrete was poured, and the permit card was signed off.

The easement is noted as a 'general utility easement.' It is not specific for drainage; however, due to other neighbors building concrete walls parallel to the easement, it channels some water in .5 to 1 inch and more of rainfall. The property and easement consists of clean, compacted soil and is essentially flat. In times of heavy rainfall, the rear of my property would turn into a virtual swamp since I am at the bottom of two intersecting grades. The street abuts my side yard. To complicate this, the street and curb are HIGHER than the easement and this is why water would swamp out my backyard.
With my retaining wall and grading above the easement, 90% of the water normally contributing to the swamping is now removed. What is left is 10-15 gallons after ground saturation that stands at one low point on the other side of the footing, in my neighbors property. Even if it flowed to the other side of the footing, it would still never climb the grade over into the street. The city falls just short of admitting that they made the street higher than the easement and they say it's private water not public water. Had they indicated it is public, they would be responsible for building a swale/culvert or underground piping to get it into the city drain.
I just need a way to get rid of the puddling. The city won't let me add to the grade to help overcome the footing or the difference in height at the street. So that's where I come in with a pump. Thanks in advance. You are a great group. Hope I can contribute in the future.
Al

 

[KRSServices]

One solution that you may have wanted to consider prior to the construction of the wall, was to negotiate with the City to provide onsite drainage through a CB and pipe and tie-in to the City storm system. As a former manager, I've had to resolve issues similar to yours in this fashion.

It would have been a little messy at first, but regarless of the road grade you now must continue to contend with water ponding. In a 1:10 or 1:25 storm, I suspect that water will once again pose a problem and pumping (trash pump) may be your avenue.

KRS Services

http://www.krs-services.com

 

[BobPE]

altor:

I read from your comments that it is improtant for you to move the water, but you have to look at the long term picture. The township signed off on the design and construction so you must consider it their problem. If you put a pump in, then ultimatley it will be your responsibility. I don't think you should nor would want to be responsible for a system that moves stormwater as if there are problems in the future from your lack of maintenance or high levels of storm water too big for your system, then you will also be responsible for the damage.

I would put it all in writing and put it to the township as their problem and ask them to address the problem, after all they are the experts...

good luck, that is not an easy problem...

BobPE