Oregon’s need for water storage and good stormwater management is substantial. Retention and detention ponds are best used in urban areas where floods are more likely to occur. They have an important role when holding stormwater runoff, by improving water quality and slowing down water flow during heavy rainfall.
What is a Retention Pond?
Retention ponds are man-made, sloped ponds that naturally collect and improve water quality. Stormwater is caught by retention ponds that hold (or retain) this water permanently, controlling its quality and quantity. Retention ponds then remove pollutants from the stormwater runoff and treat any toxic contamination. As the water is being controlled and cleaned, it is slowly released through an outlet, flowing back into the ground and streams. This results in the reduction of erosion and flooding. The terrain around the retention pond is typically covered in vegetation, which actually serves an important function for the health of the pond. Vegetation blocks off debris from reaching the pond and makes the terrain look physically appealing. However, it is essential to maintain vegetation as it grows very quickly.
Benefits of Retention Ponds
There are many ways in which retention ponds benefit the environment. It is important to understand the purpose they serve and how stormwater control improves water quality. Retention ponds benefit the ecosystem and play a significant part in how the environment is treated, which ultimately affects everyone. They are especially needed in urban cities where there is not much drainage for stormwater runoff or heavy rainfall to flow into. Having a retention pond in these areas reduces water overflow, which prevents flooding that may occur in streets and residential areas. The helpful thing about retention ponds is that the building process is pretty easy, if there is enough space. If properly built, these ponds can withstand extreme weather conditions and still have the ability to remove all pollutants from stormwater. Retention ponds improve water quality, support a healthy ecosystem, promote wildlife habitat, prevent flooding, reduce erosion, and enhance the aesthetic value of plants.
Retention Pond Maintenance
Maintaining a retention pond can be hard work, but it is essential to do in order to keep water sources clean and prevent any damage done to the surrounding land. It is not just advisable, but also required if you have a permit so that you comply and stay up to date with city codes. A poorly maintained retention pond may result in significant financial loss, which will only be frustrating when city inspectors get involved. Ultimately, an unkempt pond is not worth the stress. To keep your pond, drainage system, and pumps unclogged, you will need to inspect those issues or hire someone to identify what needs to be fixed. Silt traps are pipes that prevent silt from building up and can be used in ponds. The advantage to using a silt trap is so the pond doesn’t get clogged or harm aquatic life. The fact that fish are harmed when silt accumulates is worse for your pond since the dead fish will contaminate the water. If this is the case, you will need to remove them immediately.
In order to prevent any harm to the water quality caused by erosion, it is crucial to be aware of what is dropping into the water after mowing. Erosion can readily enter into retention pond basins. The vegetation that is planted around the pond does help with erosion prevention by holding the soil in place and stabilizing the embankment, but as mentioned, maintenance is required.
There are a few maintenance requirements every season that are inspected annually in the state of Oregon. During summer seasons: clean gutters, remove overgrown weeds, and remove waste accumulation; in the fall, replace dead plants and bare soil with new ones, and remove sediment and debris; in winter, clear out gutters; in the spring, remove sediment and debris, and replace soil and dead plants. Weeding is also necessary throughout the year. It does not matter whether you or the stormwater management operator keep the maintenance records–what matters is that they get kept. All repairs, landscaping, and cleaning needs to be recorded along with the date, description–and your contractor’s name. Best Management Practices, or BMPs, are practices proven to prevent contamination and pollution in your area. If you find contamination on your property, report it immediately so that it can be investigated.
Inspectors will check for trash, silt buildup, erosion, overgrown vegetation, and functional pumps and pipes. If you care for your pond and regularly monitor it, maintenance can be simple. Plus, dealing with the city’s stormwater management and the potential suspension of your permit is not enjoyable.
Lining a Retention Pond
Ponds need to be lined in order to prevent water spillage from reaching the soil. When this happens, saturated soil forms, making it hard to remove pollutants. Installing underlayment beneath your pond liner is not necessary, but it does provide an additional layer of protection, keeping it from stretching. If the underlayment is not applied properly, holes will appear, water will leak out, and you will have to either seam it or buy new underlayment. Clay soils are the best type of soil to use underneath the pond liner, because of its soft texture and sufficiency to hold water. Not all soils are fish-friendly. Sandy-rocky soils, or alkaline soils, for instance, do not mix well with fish. The ideal soil is one that can be compacted, comes in different sizes with high nutrient levels– and helps keep your fish healthy and happy.
Although it may seem obvious, there are multiple reasons why lining a pond will have better results than a pond without liner. It can be overwhelming to pick the right liner material and know what kinds of pipes, pumps, and drains to use. However, that part of the process is essential and will end up being worth it once your retention pond is complete.
What is a Detention Pond?
A detention pond is a pool of water that holds back surface runoff; it’s like a reservoir for rain. While retention ponds are called “wet ponds”, detention ponds are called “dry ponds”, because of their impermanent basin of water and quick discharge time. These ponds normally hold water for around 24 hours and have almost no water remaining before the next storm arrives. To maximize the benefits of a detention pond, be sure to site it on a piece of land large enough to hold stormwater run-off from a large drainage area, or the stormwater will be harder to control.
In Oregon, detention ponds are used during the drier months of the year to collect snowmelt and treat it. By removing pollutants from the water, sediment buildup in drainage systems is prevented. Although this helps, detention ponds cannot completely remove all pollutants. At the outlet of a detention pond, filtration must be installed so that water quality can be better controlled before being released back into streams and rivers.
Maintenance
Annual maintenance inspections and most maintenance requirements for detention ponds in Oregon are the same as those of retention ponds—but there are additional requirements strictly for detention ponds. It is unfortunate that detention ponds are sometimes forgotten about after their initial construction, because the extra maintenance requirements are often overlooked. Bringing such a pond up to code can be expensive and damaging to the environment. For example, by trying to fix up a pond and removing trees and shrubs that had accumulated around it, you could have easily damaged an important breeding ground for several species of birds. So with that in mind, keep your detention pond from failing, because repairing it might not be worth the time or money.
Mowing and trimming vegetation, clearing the pond of garbage and waste, and clearing silt from pipes are all basic detention pond management procedures. Checking clogged outlets, slope erosion, overgrown vegetation, water levels, pipe and pump operation, and anything else that might be harming the pond are all part of a routine inspection. Maintenance is only hard if you make it hard. If you want to avoid paying fines and other expenses, you need to properly care for your detention pond.
