Replacing Liner with underground spring

In general there should have been a french drain line under the pool floor assuming the pool was properly constructed in the first place. If you actually have an underground spring I do not think burying a sump pump will be sufficient, nor is it your best solution to the problem. Drilling or digging a well point is the best, but also the most expensive solution. Another option is to install a proper french drain under the floor of the pool with a line run back to the equipment area for future access.

A more affordable option would be to install a poor man's french drain. In this case you still create a drain field under the floor of the pool by hand digging down at least 12-18" below the existing floor(or place where spring feed is) . Continue with a narrow trench up the side slope and terminate the trench at the pool wall. The trench needs to be at least 6" inches deep to allow for the pipe to be buried and then covered with pool base. Then line the hole in the floor with landscape weed block fabric then add about 6-8" of gravel then install a 1 1/2" or a 2" PVC pipe with the last 12-18" of it slotted and capped. I only slot the bottom half (helps with maintaining prime) of the pipe by using a sawz-all to slice the pipe 1/2 way through about every 1/4". Then put the slotted pipe attached to a roll of flex pipe on top of the gravel, slots down, bury the slotted pipe in the hole with more gravel (all 3/4" Stone). Cover the gravel with more of the fabric tamp it all down leaving 2" to the floor surface then run pipe up the trench. Cut the pipe near the pool wall so you can put a 45 degree slipxfpt fitting where the trench terminates. The fitting needs to be below the pool base surface, low enough to put in a threaded plug and cover with pool base. The plug is installed after we get 6" of water in the shallow end. In the meantime thread a male adapter mptxslip into the 45 glue flex or rigid pipe into the male adapter bring it up onto the deck and hook it into a 1hp self priming pump. Put valves about 1' to 2' away of both sides of the pump, it will help regulate flow and ease priming. Close the valve in front of the pump and prime the pump and line. Then partially close valve on pump discharge. As you turn on the pump simultaneously open the valve on the suction side as the pump finally clears all the air from the suction line throttle the discharge valve open. use the discharge valve to regulate the amount of water in the hair and lint pot on the pump. By doing this we avoid the pump losing prime then allowing the water to rise above the gravel before she primes again. Be sure to spray paint a marker indicating where the fitting will be buried in the event you ever have to do another liner there you know where you have to reconnect your pump.

The idea is to keep the water below the surface of the gravel. The fabric keeps silt from clogging the drain pipe. once the water is under control cover the hole and trench with pool base once it is set up, then proceed with the liner install. Use duct tape to seal around the pipe you installed Once you have 6" of water in the shallow end you turn off your vacs, and un-thread your pipe to the pump crawling behind the liner put in the plug and cover it with pool base. snap the bead into the track and continue to fill.

Using this technique I have been able to overcome 60-80 gallon per minute inflows. In extreme cases additional lines and pumps could be used following the same concept.

Replies

Chris Lightenberg April 17, 2012 at 11:50am

In general there should have been a french drain line under the pool floor assuming the pool was properly constructed in the first place. If you actually have an underground spring I do not think burying a sump pump will be sufficient, nor is it your best solution to the problem. Drilling or digging a well point is the best, but also the most expensive solution. Another option is to install a proper french drain under the floor of the pool with a line run back to the equipment area for future access.

A more affordable option would be to install a poor man's french drain. In this case you still create a drain field under the floor of the pool by hand digging down at least 12-18" below the existing floor(or place where spring feed is) . Continue with a narrow trench up the side slope and terminate the trench at the pool wall. The trench needs to be at least 6" inches deep to allow for the pipe to be buried and then covered with pool base. Then line the hole in the floor with landscape weed block fabric then add about 6-8" of gravel then install a 1 1/2" or a 2" PVC pipe with the last 12-18" of it slotted and capped. I only slot the bottom half (helps with maintaining prime) of the pipe by using a sawz-all to slice the pipe 1/2 way through about every 1/4". Then put the slotted pipe attached to a roll of flex pipe on top of the gravel, slots down, bury the slotted pipe in the hole with more gravel (all 3/4" Stone). Cover the gravel with more of the fabric tamp it all down leaving 2" to the floor surface then run pipe up the trench. Cut the pipe near the pool wall so you can put a 45 degree slipxfpt fitting where the trench terminates. The fitting needs to be below the pool base surface, low enough to put in a threaded plug and cover with pool base. The plug is installed after we get 6" of water in the shallow end. In the meantime thread a male adapter mptxslip into the 45 glue flex or rigid pipe into the male adapter bring it up onto the deck and hook it into a 1hp self priming pump. Put valves about 1' to 2' away of both sides of the pump, it will help regulate flow and ease priming. Close the valve in front of the pump and prime the pump and line. Then partially close valve on pump discharge. As you turn on the pump simultaneously open the valve on the suction side as the pump finally clears all the air from the suction line throttle the discharge valve open. use the discharge valve to regulate the amount of water in the hair and lint pot on the pump. By doing this we avoid the pump losing prime then allowing the water to rise above the gravel before she primes again. Be sure to spray paint a marker indicating where the fitting will be buried in the event you ever have to do another liner there you know where you have to reconnect your pump.

The idea is to keep the water below the surface of the gravel. The fabric keeps silt from clogging the drain pipe. once the water is under control cover the hole and trench with pool base once it is set up, then proceed with the liner install. Use duct tape to seal around the pipe you installed Once you have 6" of water in the shallow end you turn off your vacs, and un-thread your pipe to the pump crawling behind the liner put in the plug and cover it with pool base. snap the bead into the track and continue to fill.

Using this technique I have been able to overcome 60-80 gallon per minute inflows. In extreme cases additional lines and pumps could be used following the same concept.
Brandon Ruland April 16, 2012 at 11:00am

There should be a weep line available for when the pool was constructed. If so, hook a pump up to it while installing the liner I suppose.
Norman Tyree March 26, 2012 at 11:08pm

Yes leaving a pump burried is the safest bet but if possible drill a hole (Well point) beside the pool there may be one there from when the pool was built and you can drop a pump down it at any time.

Kiwi Norman www.poolquartz.co.nz
Hank Graham March 26, 2012 at 9:51am

We would usually set a sump pump in the main drain sump to keep it pumped out while working the bottom and at the very latest moment, pull it out and quickly drop the liner. Hydraulic cement may help slow or stop the flow. I have also been known to bury a sacrificial sump pump below the hopper pad and run a hose underground for effluent. In this case, I would usually leave the power cord and hose intact and buried in a plastic bucket outside the pool deck for future use if needed.

Good luck!

Hank
- poolman58 > Hank Graham March 26, 2012 at 10:16am
  
  First post nails it!
  
  GOOD LUCK