The engineers, the drillers and the hole fillers (engineers) came and went. They made a mess of our lawn (though it causes us no grief). They drilled holes and determined the level of the groundwater (24ft) and they determined that we have differing levels of soil infiltration depending on what the depth is: up to 16ft deep is hardly permeable at 16ft and below there is a layer of gravel/river rock and the soil drains 12″ per hour. All in all good news – we’ve been able to make a drywell that satisfies the city. Many thanks to Dan, Robert, John and everyone at Adapt Engineering.