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Community and Q&A

Sealing a dry sump

Hobbit _ | Posted in Mechanicals on

My basement is fairly dry and well above the local water table
and hasn’t had any water ingress over any of the major storm
events we’ve had, and has never had a sump pump. So I don’t
really care about storm water; what worries me is the potential
for internal plumbing leaks as there’s no way for the basement
to drain until it basically fills all the way up. So I’m
thinking of putting in a sump pump but into a small well that
*doesn’t* connect to whatever gravel/earth/whatever is underneath
the slab — it would be connected to the slab and sealed in and
only communicate with the basement space itself, and thus remain
totally dry unless there was a genuine leak/flood emergency.

As discharge pipe check valves probably aren’t perfect, any
slug of water remaining in a riser pipe would eventually
vanish and might leave an air path into the basement through
the piping and pump itself. Most sump pit lids don’t seal
in an airtight fashion, either. Thus: what could be designed
to avoid air infiltration, and prevent critters from moving
into the end of an always-dry pipe hanging out the side of
the house? I’ve been thinking some sort of breakaway plug
at the outer end, sealed just enough to prevent airflow but
so that water hitting it would push the plug completely out
and let the flow go. Perhaps a second check valve right
out near the end?

As this is only being considered as insurance against fairly
rare events, it’s wouldn’t be a typical pump install. It’s
arguably another thermal bridge through the side of the house,
too, although I’d hesitate to insulate the pipe as that might
let any water in it more readily freeze.



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  1. GBA Editor
    Martin Holladay | | #1

    Jackel Inc. makes an airtight sump lid. Here is a link:

    Contact info:

    Jackel, Inc.
    15314 Harrison Rd.
    Mishawaka, IN 46546

  2. Hobbit _ | | #2

    I probably shouldn't have mentioned airtight lids ... the idea
    is to let any water in the basement fall into the pit to get
    pumped out, but to nominally air-seal the path to the outdoors
    through the pump and piping somehow. Ideally, without any
    standing water in the system...


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