20 Dec Dry Well: Solutions for Low Area Drainage Problems
Many of the best outdoor drainage solutions rely on gravity to help drain water away from a problem area to an area of lower elevation, like into the street. Grading, French drains, and drain tile systems are great solutions to help carry water away from the foundation of your house or to fix a wet area in the lawn. But these only work when there is a place downhill to send the water. So if your lawn sits 3’ or higher than the street, there are lots of options to help drain water to the road. Sometimes, though, the problem area happens to be the lowest spot in your yard or the lowest spot in the neighborhood. What do you do then? If there’s nowhere downhill to send the water or simply not enough slope to effectively move that water, a dry well or a dry well with a sump pump system might be the best solution.
Dry Well Systems
A dry well is an underground storage system that will store water while waiting for that water to filtrate into the soil.
How does it work?
Picture the puddle that forms in that low spot in your yard. Eventually that puddle filters into the ground and dries up. With a dry well system, the water that once puddled above ground instead drains into a rock-filled chamber below ground. It’s this rock-filled chamber that we refer to as a dry well. This keeps the lawn above ground dry as a bone, since the water is now being held in the dry well below ground. No more soggy lawn or waiting for large puddles to dry out; the dry well holds that excess while it’s filtering into the soil below.
How big should the dry well be?
The size of the dry well storage system depends on the amount of water being collected by the system and how quickly the soil surrounding the dry well is able to infiltrate water. For instance, sandy soils will drain water much more quickly than clay-based soils. The size can be determined by a formula based on how much area is needed to hold 1” of rain from the area that will be drained into the dry well. KG landscape will do the math to make sure the dry well is appropriately sized to meet the needs for each situation. It’s important to do the correct math rather than guess. Building too large of a dry well could be a waste of money and building one too small will not solve the problem.
Can you see them in your lawn?
Dry wells can be covered with lawn above, so you’d never know they were there. They can also be landscaped over with plants and flowers. The concept is not very different from a rain garden. The difference is there’s no requirement to dedicate the space above the dry well to a planting bed. Most customers prefer to keep the space above the dry well as usable lawn space. If you want some more information and step by step instructions, check out This Old House.
Dry Well with an Outdoor Sump Pump System
Sometimes a dry well alone is not enough to solve a tricky drainage problem. In these situations, it can be more practical to use a pump to take the water away from the low-lying area. Exterior sump pump systems are very similar to sump pumps used in basements. We can also use grading, French drains, and drain tile to help drain water from other problem areas directly into the dry well and sump basin system. It’s also common for us to also send water from a home’s gutters via underground gutter extensions into a dry well sump system.
When is an outdoor sump pump useful?
- A dry well handling runoff from large areas may need to be massive to properly store all the water. In that case, it becomes cheaper to use a smaller dry well with a sump pump rather than building a very large dry well.
- In small yards there is sometimes not enough space to build a dry well with enough capacity to hold the appropriate amount of water. Even if there seems to be space in a small yard, the dry well might need to be too close to the house. In that case, a much smaller dry well further away from the house and that utilizes a pump would make more sense.
- Heavy clay soils that do not drain well can require a sump pump. Dry wells alone are not able to infiltrate into the soil quickly enough to make room for the next rain event.
- The water table or a perched water table is near the surface of the soil. In these situations, the soil will already be super saturated and unable to hold more water.
How is a sump pump system installed?
First, we locate the lowest area of the yard and excavate soil to make room for reservoir cubes and the pump basin. Then, we line the hole on all sides with filtration fabric that is designed to allow water to move through the fabric. This fabric helps prevent soil and sediments from flowing into the void spaces created by the reservoir cubes and rock. Next, we install the reservoir cubes and the sump basin. The reservoir cubes are used to create void space in the ground that will allow significant amounts of water to collect before activating an on/off float for the sump pump. The reservoir cubes also help hold water that previously may have puddled or caused mushy soil. Once the sump basin and reservoir cubes are properly wrapped in filtration fabric, the rest of the void space is back-filled with rock. These dry well systems with a pump are usually left as rock beds since the pump basin will need to remain accessible for maintenance.
Where can the water be pumped from the dry well?
An outdoor sump pump can pump water from a low spot in the yard via pipe buried below ground. The pump sends the water somewhere outside the problem area. Most commonly, water is pumped to the curb, where it can flow into street and into the storm sewer system. Water can also be pumped to a wetland or other low-lying area. Alternatively, the tubing can be connected directly into the city storm sewer system. Each city is different as to their rules, so permits and city approval are required when hooking directly into a storm sewer. KG Landscape can help work with the city to determine which methods will be an option for each unique situation.
Drawbacks to using an exterior sump pump system
Using a pump can be much more cost effective than building a large dry well and is sometimes the only viable solution for certain drainage problems. However, there are a couple of drawbacks to consider. The first is that you’ll need to run electricity to the exterior of the house to power the sump pump, which is an added cost. The second is that most of these systems are designed for the pump to be removed during the winter months to protect from freezing, which will damage the pump. It’s very quick and easy to remove the pump, but it means there are some maintenance steps that need to be done year. The last drawback is that instead of relying purely on gravity like you would be with grading or French drains, you are relying on a pump, which can break over time. Using an exterior sump pump system can be a great solution for the most difficult drainage problems, but it’s usually only recommended when other simple methods will not work is certain scenarios.
Call KG Landscape with your drainage issues
If you’d like to know which solution makes the most sense for your drainage problem, give us a call at 763-568-7251; we’re happy to help . You can also submit a quote through our quick quote system on our website.