California did not create nine water boards to manage the entire state’s water supply just to prevent the loss of valuable fresh water. It also intended to protect natural environments and man-made structures alike from the potentially dangerous effects of uncontrolled storm water. Flooding has been a major problem in California for both rural and developed areas. Without appropriate drainage channels and ponds to contain what they collect, neighborhoods can be easily overwhelmed when summer storms dump thousands of gallons of water per hour. Retention and detention ponds are two related, but different types of storm water ponds that play important roles throughout California. Find out more if you are designing one of these ponds yourself or moving into a neighborhood that contains one.
Urban Runoff with Paved Surfaces
Stormwater can be a bigger problem in the cities of California than the rural areas due to the amount of paved surfaces. Paved surfaces, while not completely impermeable, are slow to absorb water and distribute it. Water either gathers on the surface to form dangerous puddles, that can create traffic accidents, or drains off correctly and must be stored somewhere. Retention and detention ponds are two of the best options for storing that water and allowing it to return to the environment slowly and naturally. Yet, they need to be secured when built in the midst of the urban environment since there is far more pressure from nearby residents and animals. Anyone who accesses the pond, human or animal, can slip and fall in the water and become exposed to a mix of chemicals from runoff over the city surfaces. Urban retention and detention ponds must be secured with fencing, signage, and more, to make it clear these water features are not safe for drinking, swimming, boating, or anything other activities.
Rural Flooding and Mudslide Risks
Retention and detention ponds are not used in rural settings nearly as much as urban ones. Storm water management is essential in the sloped and rugged environments of North California in particular. Without stabilization and erosion control to keep storm waters from destabilizing the hillsides and mountain valleys, many areas in Northern California would be collapsed by now. Retention and detention ponds can become essential parts of the rural landscape, but since they tend to carry lower levels of chemicals due to runoff, they often double as fishing and recreational ponds as well. These features should still be lined to encourage a healthy, natural ecosystem so that bacterial colonies form to purify the water over time; especially if the ponds are built to capture runoff from farms and livestock barns.
Small Ponds for Home Storm Water Management
Even the smallest ponds can work as storm water management features on the home scale too. From dry creeks to small ponds that stay filled year-round, there are many options for the California homeowner trying to control what is flowing out of the gutters. Dry wells are often surrounded by pond-like features to ensure that runoff can accumulate as it slowly drains into the ground. No matter the type of home water management feature you add to your yard, make sure to use an impermeable liner material to ensure the pond doesn’t lose water over time and destabilize the soil in your yard.
Retention vs Detention
While the two terms are often confused for each other, detention and retention are slightly different concepts in storm water management. Detention ponds are designed to only temporarily hold water. They will feature a drain near the bottom of the pond, allowing the water to slowly discharge into the surrounding environment and then stand empty. This only allows for minimal settling and other treatment of the wastewater.
In contrast, retention ponds are more common. These water features are designed to hold the water for as long as possible, often only allowing it to escape through evaporation in general. This allows for settling and bacterial processing, reducing the number of contaminants in the wastewater and making it safer to release into the surrounding environment. Many retention ponds are set up to either pump dry or release through temporary drains as needed when the water has settled enough. This also allows maintenance workers to clean accumulated trash out of the pond, so it does not spread into the surrounding environment.
What are These Ponds Built to Retain?
Regardless of whether the pond is built for detention or retention, it is likely to end up containing:
- Organic waste
- Bacteria
- Oil, gas, and other vehicle by-products
- Soil and sediment
- Fertilizer
- Solid trash
- Heavy metals
All of these materials can shorten the lifespan of a pond liner. Choose a product built for storm water purposes to ensure it can withstand the petroleum by-products that are commonly accumulated in runoff from roads. Even heavy metals are common in urban ponds built for holding storm water.
With careful design, California detention and retention ponds can also double as fire protection, wildlife habitat, and more. It all begins with a flexible liner material that can handle years of exposure to the elements. Don’t settle for second rate liners when BTL Liners has the products available to handle the most challenging chemical exposure situations.
