A plumber -- who didn't want to do the job for irrelevant reasons -- advised that I needed to replace an existing exterior sump pump and pit for drainage of stormwater from our lawn. There has always been a lot of ponding due to underlying clay. The pump system discharges through 1 1/2" PVC piping to a sump pump system in our crawl space that then discharges to a stormwater drain. My prior Flotec and similar Home Depot-bought pumps kept dying after one season. I was advised to enlarge the pit diameter to reduce the frequency of the on/ off cycle. I dug a 30" deep hole and installed Jackel (resin?) 18" dia. x 24" deep basin and a Storm Pro 1/2 HP Cast Iron/Stainless Steel pump with vertical magnetic float and built-in release hole to avoid air buildup. I lined the bottom of the dirt pit with about 6" of gravel. I drilled about 60 - 1/8" holes around all sides of the basin in 3 rows in about an 8" band that started about 1" from the bottom. I then covered the outside of the basin with landscaping weedblock fabric. After inserting the basin in the ground, I poured a 5" diameter layer of gravel all around the sides of the basin from bottom to top, so that I had the gravel as an outer filter and the fabric as an inner filter. The Storm-Pro had a 2" discharge hole so I used a 2" to 1 1/2" adapter to connect to existing plumbing, which had a check valve. All clamps were tightened properly and the check valve was in the proper position. I rested the pump on four bricks in the bottom of the basin to give it a little elevation from sediments. I tested the pump by pouring water in the pit and it appeared to be working. I then closed the lid and put two more bricks on top to keep the basin lid shut without having to mess with unscrewing for service.I went out to check it after some heavy rain and found that the entire pit had pushed out of the ground and was bobbing on the surface of a full pit of water! I heard the pump running, so I unplugged it. After everything dried out, I went back and looked. The filter fabric did not seem to be clogged, but about 10 to 15 of the 60 inlet holes appeared to have sediment or tiny gravel particles. (Filter fabric may not have been glued sufficiently?) That would still leave about 45-50 inlet holes. If the pit was filling up with water, that should ADD weight along with the 6 bricks. I can only think that somehow the pressure under the pit must have been greater than the pressure inside the pit. I would think that would only occur if all the holes and/or the fabric had been clogged. I am scratching my head about this. Any good suggestions? Thanks much.

The pump system discharges through 1 1/2" PVC piping to a sump pump system in our crawl space that then discharges to a stormwater drain Are you saying that you have a sump pump that discharges into another sump pump and then out side. That doesn't make much sense to me . Why two pumps. Can you explain further? Tom

Tom,

Thanks for replying. It is a bit of a crazy set-up. We have a 3600 sq. ft. ranch house that has a crawl space under almost the entire house. There was moisture in the crawl space (rising groundwater?), so the prior owner had a waterproofing company come in and encapsulate the crawl space with thick plastic, install three sump pumps in the interior of the crawl space, and then two heavy-duty Zoeller pumps at each end of the crawl space. Each end is accessed through storm-cellar doors. The sump pumps all discharge to a central line that is piped to a storm sewer connection at one end of our yard. The one exterior sump, as I explained, handles the water from our one lawn that does not drain well and this pumps into one Zoeller pump that then pumps through the line to the other Zoeller pump which then pumps to the storm drain. Sounds like a nightmare. It is not bad as it sounds, but I would never buy a house with this set-up again. Otherwise it is a really attractive house. Anyway, I hope this helps you understand the set-up. -Perry

" bobbing on the surface of a full pit of water" this say to me that you pit was water/air tight. It should not be with all the holes you drilled but how else could it float? Why did you use weedblock instead of a more porous fabric? I think the weedblock is not very porous.

Hi Ballengerb1. I asked for filter fabric at Home Depot and they steered me to weed block, saying that it would be better for my purpose. The weedblock is supposed to be porous enough to allow water to get back into the ground, but you may be right that it is not well-suited to this purpose. Still, it may be that I simply need to drill the holes larger.

I think the number of holes is OK but don't rely on clerks at HD for much advice. Test out your fabris by making a bowl shape over a bucket, pour water into the bowl. How long does it take to drain?

I drilled about 60 - 1/8 holes"

Lots of holes but not nearly large enough. Drill out to something smaller than gravel but at least 1/2". Each time pump empties the sump crock there will be an upward pressure by the water underneath the crock pushing it up as water tries to make its way into the crock. You may be able to drill holes with out removing the crock if you can reach the bottom. You could just cut out the entire bottom since you have the pump sitting on brick above the gravel. Do anything you can to let the water in faster.

Thanks to everyone for your advice. The consensus was to increase my hole size from 1/8" to 1/2" and I did that. I also drilled 8 holes in the bottom, which I didn't have before I also tested the weedblock fabric by placing it over a bucket and pouring water. Sure enough, the water just ponded there; it barely dripped through. That makes me wonder how weedblock allows plants to get enough water. Anyway, I found a drainage pipe filter fabric sleeve and cut this open and tested it for porosity and it worked just fine, so I affixed it to the bottom and around the sides to cover the holes. I then reinstalled in the ground, surrounded by gravel. This time I tested by pouring water down the gravel and it did seem to readily enter the sump pump basin readily. So, there you have it. Just waiting for the big rain to really test it. Thanks again everyone. The collective wisdom was very helpul. -Perry