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Question DetailsAsked on 8/1/2016

Need an engineer, maybe? How do I check the flow rate of a tiny spring that just sprung on my hillside property?

I'm on one cleared, terraced acre of a mostly wooded hillside; house faces east, UPhill.. The new spring is maybe 25 feet southeast and uphill. Its made an itty bitty swamp out of the front yard up there. I don't mind it, in fact, I'd turn it into a landscape feature if i knew what to expect from it. However, if it flows any stronger, I don't think the terraced terrain can keep absorbing it. I don't want to have to put in a french drain. So I need to track it and see if it the flow rate is increasing. When I first noticed it about 3-4 weeks ago, the swamp was about 6 x 3, and mostly just a soggy patch. Now, theres a distinct flow area in it, the soggy bit is now holding an inch of water on the surface, and the area is now about 10 x 3, and though it is inching toward the house, the surface still absorbs it at the edges of the puddle. It's not bothering anything now, but I want to know what might be coming down the pike, in case it's trouble. I have pics, if that'll help. Thank you!!

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For flow rate, you would have to trap the outflow where it comes out of the hillside - maybe dig a bit of a depression and sandbag or berm the front, and line it with plastic sheeting to trap the water, then have an overhanging overflow "spillway" (maybe over a board under the plastic to provide a lip) where you could put a container like a gallon or two bucket or pan to catch the water and time how long it takes to fill a known volume container (determined using a kitchen measuring cup), to figure out the flow rate in gallons per minute. Of course, there would likely be a lot more water flowing through the ground as groundwater that you are not seeing- quite likely a vast majority of the water if not popping to the surface because of bedrock or clay layer that it cannot seep down through.


First thing I would be looking at, maybe after getting a utility locate for water/sewer lines on the hill, is whether there is a water or sewer line that this could be coming from. Also, whether there is an uphill neighbor who could have a broken line, leaking swimming pool, or maybe just draining their swimming pool that is the source. It is quite rare for a new spring to just pop up on a hillside unless you have had inordinately rainy season AND there is an impoundment (pond, depression etc) uphill of you. Also, long before it popped to the surface, you would usually have seen lusher vegetation in that area, or maybe winter icing.


Or an uphill neighbor has changed their practices and is watering a lot more, installed a drip system that is overdoing it, has broken sprinkler line saturating one location,, or changed their yard drainage or roof runoff routing. One of the first things I would be doing if your water line or neighbor's sewer line does not come from that area is visiting uphill neighbors to ask them about water dumping or losses, whether their water usage has gone up (if metered, etc).


Whether this is a "spring" or a leak, even though it is soaking into your yard that does not mean it will not become a problem, because sounds from the topography in your yard that it will flow downhill underground till it hits your foundation - which could cause wet crawlspace/foundation issues. Add to that the fact that perhaps only a small portion of it is breaking through to the surface and you could be looking at a house potentially sitting in an underground swimming pool, effectively, as it migrates downhill.


Of course, how steep the hill is would be a matter of concern too - if a steep hill - generally steeper than about 30 degree slope (2 feet horizontal to 1 foot vertical rise) and not sound bedrock, or even flatter if sandy or water-softening clay or such, slope instability from the wetting causing greater weight and the added lateral hydraulic pressure from the water in the hillside plus weakened soil would be a concern with regard to possible land slippage.


If you (and maybe do same thing in conjuction with uphill neighbors) turn off all water usage in the house and then hold ear or stethoscope to water pipes, if you hear water running (with circulating pumps on boilers or water heaters and otehr noise sources or such turned off) then likely coming from a water pipe leak. If uphill neighbor's leach field (if they have one) has lush green grass over it, likely their field is saturated and leaking down to your area. COuld also be an overflowing septic tank uphill from you.


It is possible to have a test lab test the water for a few hundred $ (using water straight from the ground, not water that has flown over lawn) for fecal colliform, nitrates, mineral content and hardness and chlorine content - which if it has not flowed a long distance through the ground can give an idea in many (though not all) cases whether this is natural water, sewage, or chlorinated public water by comparing it to the public water supply water quality data, and if it has significant fecal coliform almost certainly sewage sourced. Sometimes water utility will do this for free if they cannot find a water pipe leak that could be the source.


Professionally, though not cheap, the person to track this down and assess the slope stability and foundation leakage risks would be (not an Angies List category) a Geotechnical Engineer (soils and foundations and groundwater specialist) - usually work for a Civil Engineering firm that does heavy foundations and site development work.


My gut feeling - unless you have had unusual amount of prolonged rain recently, since you say it popped up 3-4 weeks ago, is that this is leakage or a diverted drainage issue, not a natural spring.

Answered 2 years ago by LCD




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