Executive Summary
- Dry well installation can effectively manage water runoff and prevent property damage from excess rainfall. Choosing the right location guarantees proper drainage and increases system efficiency.
- Selecting the appropriate location for a dry well requires assessing soil type, topography, proximity to nearby structures, aesthetic appeal, and accessibility for maintenance.
- You should also consider high water table concerns, calculate the capacity for water runoff, and ensure compliance with local regulations.
- Hiring environmental professionals for site assessments and planning facilitates successful dry well installation and long-term regular maintenance.
Learning About Dry Well Installation Locations
It is no secret that the northwest part of Oregon is prone to heavy rain. Portland-based property owners should consider dry well installation to manage water runoff. These systems can direct excess water away from the foundation of a home or other vital structures to help maintain proper drainage and reduce the risk of flooding.
Nevertheless, the effectiveness of a dry well primarily depends on its placement. For example, you should identify drainage types and evaluate distances between other structures to achieve successful installation. You should also consider accessibility to facilitate regular maintenance and future dry well services.
The guide below will give you helpful insight that can make choosing the right location for a dry well installation easier. Still, you should contact an experienced environmental specialist for a site assessment and assistance with planning to promote informed decision-making.
What is the Purpose of a Dry Well?
The purpose of a dry well is to collect and disperse excess water that cascades from surfaces like roofs, driveways, and lawns. By channeling stormwater to ideal spots for groundwater absorption, this landscaping tool can prevent water runoff from accumulating and creating breeding grounds for mosquitoes, causing erosion, and inciting other water-related issues.
In addition to avoiding issues on your property from water damage, dry well installation can reduce the burden on municipal water systems, which may already be overwhelmed with gray water. Additionally, dry wells can recharge groundwater by causing more water to drain into the ground, replenishing aquifers and underground water sources.
How Does a Dry Well Drain?
Most dry wells receive water runoff through a series of inlet pipes connected to downspouts or drainage systems. Once inside the dry well, water gradually infiltrates the surrounding soil using the power of gravity and the well’s unique design, which typically includes perforated sides and a gravel-filled base. This draining process facilitates the dispersal of excess water and mitigates the risks associated with surface pooling from heavy rain.
When is Dry Well Installation an Effective Drainage Solution?
Dry well installation is especially beneficial for properties with insufficient natural drainage. Some examples of signs that make a property a good candidate for dry well installation are:
- Consistent pooling near foundations or low-lying areas after rainfall
- Frequently soggy lawns
- Soil erosion around the property
- Overwhelmed gutter systems during heavy rainfall
- Moisture intrusion in lower levels of a home, such as basement flooding
- Insect infestations in the yard due to extra water
In addition to the abovementioned situations, any home with limited access to municipal stormwater infrastructure should consider getting a localized water runoff management system, like a dry well or French drain, to ensure proper drainage.
Tips for Selecting the Right Location for a Dry Well
Choosing the optimal site for a dry well will play an essential role in its overall performance and longevity. Consider the following factors in the tips below before installing a dry well to increase your chances of achieving effective water runoff management.
Assessing Local Geology and Topography
You and a qualified professional should survey your property to understand its geological composition and landscape contours better. Look for sections with natural slopes promoting gravity-fed drainage; placing the dry well here can boost the system’s efficiency. On the other hand, flat areas may be less ideal for dry well installation—they require additional planning to ensure effective water runoff management.
Identifying Well-Draining Soil Types
In addition to looking at the shape of your land, you and the environmental specialist should consider soil permeability, which directly affects a dry well’s potential to disperse excess water effectively. For example, sandy or loamy soils are often optimal for dry well installation due to their high infiltration rates. Conversely, dense clay soils can impede drainage and demand alternative solutions like soil amendments to make the location as suitable as possible.
Evaluating Distance from Building Foundations
After getting a feel for the land itself, you should focus on the structures throughout the land. To minimize the risk of issues on your property from water damage, dry wells should be installed at a safe distance from any building foundations on the property.
As a general rule of thumb, there should always be a minimum of 10 to 15 feet separating dry wells from building foundations. Following this rule can help guarantee that infiltrating water does not jeopardize the structural integrity of the building.
Checking for a High Water Table
A water table is an underground boundary that separates unsaturated soil and rock from a saturated zone that holds soil and rock filled with water. Before installing the dry well, you must determine if the prospective area has a high or low water table.
A high water table can reduce the effectiveness of the water drainage system and pose contamination risks. Thankfully, qualified professionals should have the knowledge and tools needed to assess the depth of groundwater and ensure the planned dry well will be able to operate within safe and functional parameters.
Calculating Water Runoff Volume Capacity
An essential step when selecting the proper location for a dry well is estimating the volumes of water that the dry well is expected to handle to ensure it is adequately sized for its intended load.
These calculations should consider a myriad of factors, such as roof size, average rainfall, and runoff coefficient which accounts for the surface’s impermeability—most impervious surfaces like roofs and concrete have a runoff coefficient between 0.9 and 1.0 while more pervious surfaces like lawns and gravel usually have a runoff coefficient of 0.3 to 0.6.
Many professionals use the following formula to estimate runoff volume:
Runoff Volume (ft³) = (Drainage Area (ft²) × Rainfall Depth (inches) × Runoff Coefficient) ÷ 12
So, if a 1,000 ft² roof has a 1-inch rainfall and a runoff coefficient of 1.0, the equation would read:
(1,000 × 1 × 1.0) ÷ 12 = 83.3 ft³
Then, suppose the property owner is using a gravel-filled dry well with 40% void space. In that case, you should divide the runoff volume by 0.4 to determine the required dry well water volume, which would equal 208.25 ft³, indicating the dry well size you would need for that fictitious, demonstrative area.
Even if you are confident about your calculations, relying on an overflow emitter to indicate when the dry well has exceeded its water flow capacity is crucial.
Compliance with Local Regulations and Permits
At this point, you may feel like you already have an ideal spot for your dry well selected. However, you should still verify local building codes and review environmental regulations before proceeding with dry well installation.
Some jurisdictions require permits and have specific guidelines regarding the placement and construction of dry wells that are designed to protect groundwater and safeguard public health. For example, Portland requires dry wells to have a 5-foot setback from property lines and a 10-foot setback from building foundations to be compliant.
Consulting with Professionals for Site Assessment
Engaging with experienced environmental specialists can provide valuable insights about dry wells. Some examples of things they can help with after performing a thorough site assessment are:
- Site suitability
- Water table evaluation
- Design considerations
- System sizing and capacity planning
- Regulatory compliance
By helping with the items above, the environmental professional can facilitate the proper installation of your dry well.
Ensuring Accessibility for Future Maintenance
When selecting he dry well location, it is important to think about how easily accessible it will be for follow-up inspections and regular maintenance. This foresight ensures that future cleaning or repairs can be conducted with minimal disruptions and expenses. Plus, ensuring the dry well area is placed somewhere easily viewable can make it easier to see the overflow emitter, which indicates troubles with water dispersal due to excessive amounts of water entering the dry well.
Avoiding Potential Contaminant Introduction
To promote safety, you should position the dry well away from potential contamination sources, such as septic systems, chemical storage areas, or waste disposal sites. Doing so will make protecting groundwater from chemicals and unwanted water sources easier, preserving quality and complying with environmental regulations.
Considering Aesthetic Integration into Landscape
While functionality should be the primary focus, it is also important to consider aesthetics. If land suitability permits, try to select a place that seamlessly integrates the dry well into your landscape design. Some common routes taken to boost the aesthetic appeal of dry wells are:
- Using decorative grates
- Camouflaging the hole with landscape fabric
- Strategically planting vegetation around the dry well
- Incorporating the well into existing garden features
The techniques above can help you avoid drawing attention to the dry well’s placement.
Let Alpha Environmental Help You With Dry Well Installation
There are numerous considerations that should be taken into account before dry well installation to prioritize proper drainage of excess water. Picking the best location can be challenging without the help of a trained environmental specialist due to the erratic movement patterns of water runoff from heavy rain. There are many things to ponder, from the topography of the area to the accessibility of the dry well.
Alpha Environmental has substantial experience working with dry wells, offering services like dry well sampling, regular maintenance, decommissioning, and registration assistance to the people in and near Portland, Oregon. Our skilled team can offer peace of mind through dependable well-related guidance tailored to your property’s unique needs—we can help you determine the optimal location and proper depth of a dry well, which typically ranges between 3 and 4 feet deep.
Contact Alpha Environmental for a wide selection of dry well services that promote effective water runoff management in a way that prioritizes compliance with local regulations.
