In a message dated 10/18/2003 1:21:49 PM Central Daylight Time,
kirk78h@… writes:
Hi Everybody -
I’m new to this list, and hope that somebody out there can help me
with my pool nightmare.
Background: I had a 20×40 vinyl liner pool installed in the spring of
2002 (in the middle of a drought). I live just north of Baltimore
Maryland. The summer of 2002 was fantastic — everyone loved the
pool. And then, the nightmare started.
When I opened my pool this spring, I was horrified by the way my
liner was wrinkled across the shallow end of the pool. It had formed
what looked like a huge asterick (*) pattern from side to side.
After some investigating, I was told that my liner had floated and
resulted in the wrinkles. I “lived” with this over the summer due to
scheduling difficulties with pool service companies, etc. A few days
before my liner was scheduled to be reset, I watched my liner float
again. It was about twice the size of a large beach ball in the
center of the asterick pattern. It went completely down within 5-6
hours, but left worse wrinkles than before. It must have also ripped
my liner somewhere, because I am losing about an inch of water a
day. I have a diver coming out today to try to patch any leak. I
have a closing scheduled for Oct. 31.
Now, I know I have to do something about the recurring water
problem. I have been advised three different strategies:
1. Do nothing. This is the wettest year in decades and the ground
water problem will probably never be like this again.
2. Build a French Drain around the pool to redirect surface water.
The surface water is legit because it has washed away the dirt under
my decking. I am, however reluctant to believe it could accumulate
under my pool and force the upward pressure on the liner necessary to
displace that much water.
3. Install a sump pump as close to the shallow end as possible and
pump water away from the pool. This strategy would probably also
require the French Drain approach, so I’m sure it would be expensive.
Kirk,
Can I ask how the pool was constructed. Does it have a hard bottom or just
sand?
Before you can assume the ground water will not be a problem again you must
know where the normal water table is. Are you near a river or creek or even an
unlined drainage ditch? If you pump ground water away where will you pump it
to and that will be a never ending task. If the problem is runoff from
somewhere then the french drain idea may just work. What you really need to
look
at is…………………is this problem ground water or
runoff………………..if it is runoff where is it coming
from………………..if it is
runoff can it be redirected away from the pool area. Also what type of soil is
around the pool a hard clay or a sandy soil? If it is hard clay then runoff
will
stay around the pool.
Do not underestimate the power of water. I have seen IG pools picked up by
ground water and if you think about it for a moment your pool weighs as much as
2 fully loaded 18 wheelers.
Ken
(unknown)
April 13th, 2005 · 1 Comment
Tags: filters
1 response so far ↓
1 janis_40 // Apr 16, 2005 at 8:12 pm
So you have no hard bottom on the pool. The ground water has broken through
a crack and bubbled up the liner. I would think with hard clay they would
have put some type of french drain around the pool to handle runoff but I guess
not. Because you did not mention the sides I must assume they are either
preformed, concrete or block construction and because the bottom is not a
support
structure they must also have a footer.
From what you have said the pool would not be lifted by ground water because
there is nothing for the water to push against. A three inch mortar base is
not strong enough to support the weight of the pool so that is why the liner is
bubbling up. The water finds a crack and pushes on the liner.
It is not unlikely that there must be some natural channel for ground water
near your pool. Clay being the hard material it is will channel the water
rather than absorb it so there may be a stream under your yard that is only
active when it rains. So how do you find it…………….dig. Personally I
think
you need a hydraulic engineer or at least someone familure with fluid
dynamics to assist you. My personal opinion is that you cannot stop the water
but
only divert it away from the pool.
One other question I have is did they pour walls or install walls that were
the same height all the way around the pool and then fill in for the shallow
end? And if so what you may have is water that has found it’s way inside those
walls and hydraulic pressure from the ground water or runoff is causing the
bubble. Water will seek the path of least resistance and that in part just
may be the shallow end of your pool. The bubble forms at high pressure and
decreases when the pressure subsides.
The water may be gathering for miles and the pressure behind it may be great
just from sheer mass of the water.
(A little story about water. Back in the mid ’80s I lived in Austin Texas
and the city was growing very rapidly on the north side. Much land that was
open and able to absorb water was paved over so runoff was diverted into sewers
and creeks. These in turn fed into a large drainage ditch that ran down
through Austin toward Town Lake. One year we had a hard fast rain and this
ditch
had grown over in places to the point it could not handle the runoff from the
northern part of the city. When that water let loose the damage it did to a
portion of the older business district just north of the lake was tremendou.
There was a Mazda dealer there and the force of the water pushed all of the cars
against a wall at the back of the lot and piled them up like toys. This was
no giant flood like you see from the Mississippi but just a flash on a small
creek that could not handle the load.)
Ken
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