Effects of man-made ponds on well water

[Big ole Boy]

I visited a property yesterday that is in a well known area of Bradford, County, Florida - an area well known for its superior water quality - a rural area where water is obtained from wells for residential housing.

..... the owner of the house lives on 1 acre and decided to dig a deep pond that was right on top of a natural spring. The pond is about 30 years old now and the water level has dropped about 4 feet in the pond. The pond itself is probably 100' feet in diameter.

The well is a 4" well that goes down 400 feet.

THe owner was cursing himself for going down so deep. He believes that he should not have gone down into the aquifer ....... his water quality is terrible........

.... the proximity of the pond to the well is about 50 feet.


.... now this is an area where water is supposed to be terrific ....... but I am wondering if the proximity of the pond which is about 25 deep is affecting the the well ......

...... would it be logical that the water from the pond may be leaching into the well .......

.... my thinking is that ground level water may be at a pressure that easily finds its way into the well system ...... ?


.... just wondering what others may think ......

.... this could be a very nice place if the water was better ..... the water leaves a deep black residue on the inside of the toilet bowls and tank ......

... my question is ...... with only an acre of land ....... do you think it would be feasible to go 200 or 300 feet away from the pond and try a new well ?

 

[Wendy]

Has he had the well water tested? or the pond water? I'd think comparing test results on the two might answer some questions.

Sounds like he needs to try a new well regardless.

 

[Big ole Boy]

. very smart .

very good observation .... thank you .... two minds are better than one ....

...sometimes one mind gets overloaded with observing the subject ... then another mind can take over and see a ribbon .... that binds ...

 

[Ray Miller]

Sounds like he has what we call "Skunk Water" from his well. The water test would be the first place to start.

 

[Terrel L. Shields]

The Geology of Shallow aquifers in Florida is quite complex and although I am not an expert in Florida Geology I would suspect there could be a link but the proposed solution might not be a bit of help. First, ponds are potential sites to accumulate nitrates and pose an additional risk of taking bacteria into the acquifer. The middle part of Florida is heavily "Karst" - solution dissolved rocks that mean there are plenty of springs, caves, and pathways between surface and subsurface waters.

Black residue can be a precipitate from bacterial action or it could be a mineral deposit. Typically it will be iron (ferric) which is reddish brown or manganese which is brownish-black. This is suspended in the water in many forms and some sort of oxidation process has to be used to precipitate, then remove the 'junk'...

http://www.bae.ncsu.edu/programs/extension/publicat/wqwm/he394.html
(note- the columns didn't line up on the quote below)

Symptom Cause Treatment

Water clear when drawn, Dissolved iron or Water softener (less than 5 mg/L of
reddish-brown or black particles manganese. iron)
appear as water stands; reddish- Aeration (less than 25 mg/L of iron).
brown or black stains on fixtures Oxidation/Filtration (less than 15
or laundry. mg/L of iron plus manganese).
Chlorination-Filtration (greater than
10 mg/L of iron).

Water contains reddish-brown Iron particles from Raise pH with neutralizing filter that
particles when drawn; particles corrosion of pipes also filters particles.
settle out as water stands. and equipment.

Water contains reddish-brown Oxidized iron, Particle filter (if quantity of oxidized
or black particles when drawn; manganese, or both material is high, use larger filter than
particles settle out as water due to exposure of in line, e.g. sand filter).
stands. water to air prior to
tap.

Reddish-brown or black slime Iron bacteria. Kill bacteria masses by shock treat-
appears in toilet tank or from Manganese bacteria. ment with chlorine or potassium
faucet. permanganate, then filter; may re-
quire continuous feed of chlorine or
potassium permanganate, then filter.

Reddish or black color that Colloidal iron, Chemical oxidation with chlorine or
remains after 24 hours. manganese, or both. potassium permanganate.
Organic-complexed
iron, manganese, or
both.

The drilling of a deeper well poses the risk of entering a deep aquifer that contains salt. In this case I would be curious how much casing is in the well. A deep, cemented casing should minimize the amount of surface waters getting to the aquifer....and in that country I am betting it is difficult, if not impossible, to seal a well casing with much success. I would bet they drill wells with reverse circulation and a 4" well is a very small hole for us folks more accustomed to hard rock country.

Rather than drilling the well deeper, I suggest filling in the pond would be more likely to improve the water quality or drilling the well further away, as far away as possible, in fact. And in either case, the success ratio might be pretty low.

 

[Restrain]

Lake should not affect the well. It may be the aquifer. For example, my well is about 400'. We have a pond of about 1 acre. Now, we have "skunky" water at times, but that's a bacteria in the well casing, easly treated with Clorox.

Could well be the result of the drought in Florida.

 

[Terrel L. Shields]

For example, my well is about 400'. We have a pond of about 1 acre.

But that is in "hard Rock" country and not karst. The rocks in FL are younger, softer, mostly carbonate and lacks shale.

 

[Mr Rex]

And the OP mentions that the pond is located on an active spring. When drought hits, the spring is "drinking" dirty pond water into the underground aquifer rather than spitting it out.:icon_idea:

 

[PropertyEconomics]

Terrel ... would it be possible to drill the well on the opposite side of the pond and catch aquifer water prior to being "polluted" by the pond? I dont know the answer honestly and was just curious if a well "upstream" would have the same poor quality.

 

[Terrel L. Shields]

If you can tell which side is "upstream". The problem with carbonate (limestone, dolomite) karst is that water travels thru fractures and fissures rather than though a porous medium like sandstone. And there are no sealing beds (shale) to prevent vertical migration of the water. So in a region where you might think the regional flow is say north, locally the water is flowing in every direction according to what the rocks are doing underground.