Hand excavated french drains for green inspired Portland, Oregon. Keep Oregon green. Living and working in the Portland, Oregon area produces a deep respect for the beautiful place I call home.
Many of us have been here for decades, and wouldn’t live anywhere else. For me, the original attraction to Oregon was the clean rivers, majestic mountains, huge fish, and wonderful mountain environments.
It was the diverse nature of this state, with everything from Ocean to desert to mountain, that made me a “lifer”.
Installing hand excavated french drains and dry wells prevents rain caused heavy stormwater runoff from overflowing the sanitary sewers, that get flushed by the storm sewers in parts of Portland, with heavy rains.
These older storm sewer systems are being modified as we speak, in the city of Portland, Oregon. Many homeowners living in neighborhoods in Portland have had their downspouts removed from rain drain discharges on their homes, which were likely plumbed to the street and into a storm sewer, only to have heavy rains saturate the side of their homes foundation after disconnection, producing groundwater in the crawlspace or basement for the first time ever. These old rain drains are usually made of cast iron or clay and run to the storm sewers. Replace these installations with new dry wells and rain drain discharges that perk groundwater back into the soil.
Rather than letting that roof water drain next to your foundation, creating hydrostatic pressure and basement or crawlspace leaking, vent the downspouts inside hand excavated french drains, containing perforated pipe for groundwater, and solid ads 3″ flexible solid pipe for the new rain drain discharges that vent the downspouts, as they both slope to a 4 foot deep by 4 foot in diameter, river rock filled, and supported, drywell.
Rock filled drywells are more stable than concrete tanks, in my opinion, that are hollow, with a top, and can collapse, due to their heavy weight, or with the weight of a backhoe or pickup truck, for some future homeowner, who did not have a clue that it even existed, to suffer.
The large concrete cylinders recommended for these types of concrete cylinder filled dry wells, with river rock around them for a foot or two, are usually covered with concrete tops, that can crack in time, and are usually mandated to be covered with 2 feet of dirt.
The cylinders just sit on the dirt anyway, in a huge machine dug hole, perhaps 4 to 5 times the size of the average dry well, partially filled with drainage river rock placed around the cylinders only, not inside the cylinders. The dirt is your cylinder in a properly installed hand excavated dry well. More stable and safe is your default choice here, in my opinion. While this may seem a great feature to have more open space within the center of one of these monstrosities, that becomes the drywell for probably the entire house in most plans, venting all roof water and french drains as well into one place; it sacrifices stability and safety as I have previously indicated above, and worse yet, deposits all the groundwater in one area instead of perhaps 3-5 dry wells that are small, but cumulatively have the same amount of collection space as the monstrosity.
Keep in mind the objective is to spread the perking of the groundwater to various areas around the yard, to correspond to the areas where french drain and rain drain installation is taking place, using existing slope, or compensating for the lack of slope in the engineering plan to begin with.
Whether groundwater perks into an open tank to hit the bottom, or through river rock to hit the bottom of the dry well, makes no difference to the gravity flow of the groundwater. In both examples the groundwater will perk below grade in exactly the same manner as in the monstrosity tank system, and usually at about 20% of the cost too, when you include the fact that additional installation is many times needed to install an overflow drain field much like a septic system for the huge tank sometimes mandated by cities, just because the volume of groundwater is so high to be deposited in one area.
The builders and city planners have a way of over designing the storage areas, by venting everything into one large concrete surrounded dry well hole in the ground, with a concrete tile, with holes in the sides, which sits in the hole with rock around it, rather than supporting the sides and volume of the dry well. At any rate, the groundwater in a rock filled and supported dry well, as I advise, perks into the ground in the same manner as the overkill concrete cylinder type described above.
The amount of groundwater and roof water collection area must be estimated, to determine the number and size of these rock filled dry wells, to meet the requirements of the homes roof and groundwater collection and mitigation needs. Your professional home drainage contractor may also be familiar with your particular neighborhood, and may advise you that because your site is almost all big river rock anyway, that the amounts of dry wells used may be reduced, because groundwater cannot stand in them at all, even if they are a mix of clay and river rock of various sizes up to the size of a bowling ball. Dig a dry well around 30th and NE Fremont in Portland, and you will find it is a rock quarry, that was formed from when the Columbia river gorge was carved following the draining of the parent lake of the Utahs, Great Salt Lake.
In most cases groundwater only stands in a dry well a few weeks during and after hard rains, and only in the beginning. Once the dry well is broken in, from a few rains, and dries out again, the cracks on the bottom of the flat bottom clay dry well get larger, and the groundwater leaves quicker next time.
Portland area residents are living here because we believe it is the best place on earth to live. We love our culture, our rivers, our parks and the green trees and grass that give us that sweet smelling air to breathe. We gripe about the rain, but we love the green Oregon landscape.
Protect our environment. Love your planet. Think “green” groundwater removal. “Perk”, groundwater science is the old school answer. It is still the hot news thousands of years later.