1. Missed the live Ask the Expert event?
    Not to worry. Check out the archived thread of the Q&A with Ken Hutcheson, President of U.S. Lawns, and the LawnSite community on the Franchising Forum.

    Dismiss Notice

Drywell calculator

Discussion in 'Hardscaping' started by bigviclbi, Aug 11, 2012.

  1. bigviclbi

    bigviclbi LawnSite Senior Member
    from nj
    Posts: 894

    A customer would like to tie his gutters into a drywell. How do I measure how big of a pit I need to dig? The soil is sandy so it drains well. I was going to do a 4'x4 pit filled with 1"-2" gravel. I'm sure it has to do with roof sq ft and amount of rain but the only formulas I found had to do with soil analysis. Looking for a quick real world answer. Is one of the basins they sell at supply yards that much better than a gravel filled pit?
     
  2. GreenLight

    GreenLight LawnSite Senior Member
    Posts: 462

    That's a LOT of water for a drywell to handle, especially a 4x4 drywell. One downspout is easily capable of putting out 10 gallons per minute in heavy rains. If you had two tied into it, you could quickly put 100-200 gallons in it in 10 minutes during steady rain.
     
  3. tadpole

    tadpole LawnSite Bronze Member
    Posts: 1,216

    Install a rainwater harvesting system. HO would have extra FREE water available for irrigation.
     
  4. DVS Hardscaper

    DVS Hardscaper LawnSite Fanatic
    Posts: 6,403

    An engineer can calculate it.

    But I never had a dry well engineered.

    We usually do 6x6x6
    Posted via Mobile Device
     
  5. bigviclbi

    bigviclbi LawnSite Senior Member
    from nj
    Posts: 894

    Thanks. It's not the whole house only three gutters which is about half the roof.
     
  6. tadpole

    tadpole LawnSite Bronze Member
    Posts: 1,216

    If you know the area (sq/ft) of the portion of the roof involved and find your local rainfall rate (seasonal), you can easily determine the required capacity of a drywell or a reservoir for a rain harvesting system.
     

Share This Page