The location of this earthcache is Marsh Creek Rain Garden Park. There is imited parking available at the park. Also, wheelchair parking and ramps are provided. You will be walking around on a short paved path around the park to view the earthcache and to make your observations. You must only walk on the paved path and grass. Do not walk through the rain garden or the pond.
The Marsh Creek watershed is in Sandy Springs in the Chattahoochee River basin. The Marsh Creek Rain Garden is an environmental park that uses rocks, stone, soils, and plants to treat and filter stormwater runnoff before it runs into Marsh Creek, and is the area's "first urban stormwater treatment park".
As you drove to this area of Sandy Springs, you would have noticed it is surrounded by homes and businesses with many rooftops, driveways, streets and parking lots. Rain that falls on undeveloped land like fields and forests will soak into the soil. But hard surfaces like roads and parking lots are impermeable which creates what is caused "stormwater" when it rains.
As stormwater drains down the parking lots and streets into storm drains, it collects pollution such as fertilzer, pesticides, sediment, motor oil, litter, pet and yard waste, leaks from sanitary sewer and septic systems. This stormwater runoff does not go to a treatment plant. It will usually flow through storm drains and eventually to our riverr, streams, and lakes. Before, this 4-mile section of Marsh Creek had seen bacteria increases to levels that were outside the state's water quality standards.
This rain garden park has two main functions: to contain stormwater runoff and to scrub pollutants out. It treats the water and reduces the bacteria levels through natural means. Rain gardens use the concept of bioretention, a water quality practice in which plants and soils filter pollutants from stormwater. The garden itself is a garden of native shrubs, perennials, and flowers planted in a small depression, which is generally formed on a natural slope. The rain garden is not a wetland. In fact, it will appear to be dry most of the time because the water infiltrates quickly by design. During heavy rain, the basin might fill up temporarily but it should empty within a matter of hours. Biorentention areas/rain gardens usually don’t hold water for more than 48 hours, to keep mosquitos from breeding.
Stormwater enters the park through large drain pipes. Boulders are placed in front to protect the garden from erosion. The garden has been planted with deep-rooted native plants, grasses, and shrubs. This plant life absorbs the organic pollutants while also providing food and habitat for butterflies and other pollinators.
The soil used in the garden and pond is engineered with a blend of sand, clay, organic matter, etc. The clay that is naturally found in this area does not allow for much infiltration which is why a man-made mix of soil is required.
As the stormwater soaks through the soil, gravity pulls it into a layer of stones where it is forced into pipes through a series of small holes along their length. These pipes transport the water to the pond. At this stage much of the physcial pollution in the water has been removed.
However, there are still pollutants existing that is dissolved in the water. That is where naturally occurring microogranisms come in. These microorganisms live in our ponds, lakes, and rivers, but are so small, they are impossible to see without a microscope. Fortunately they are harmless to humans, but they do love eat the dissolved pollution in the water. These microorganisms thrive and grow when there is more dissolved oxygen in the water. The fountain in the pond helps by circulating and aerating the water.
The cleaner water is released from the park in a controlled manner to prevent flooding and erosion. The City of Sandy Springs estimates that it can hold about 90 percent of rain from normal rains and 50 percent from heavy storms. It will flow through Marsh Creek and Sandy Springs neighborhoods, providing cleaner habitats for fish, amphibians, birds, and plant life. It will continue downstream and ultimately flow in the Chattahoochee River, where it becomes a major source of our drinking water.
You must answer the questions below and send them to me to be able to log your find. Click on "Message This Owner" above to send your answers. If you fail to send, your log will be deleted.
1. Please describe what the rain garden looks like on the day of your visit. Its appearance will vary depending on the time of the year and recent weather.
2. Compare the elevation of the rain garden to the pond. Which one is higher? Why do you think that is?
3. Based on your observations, describe where do the cleansed water leaves the park and enters Marsh Creek.
4. Post a personal picture in your log of your GPS, yourself, a thumbs up, etc. at the park.