Stormwater runoff contains many pollutants.
Stormwater runoff is a significant cause of pollution and impairment of the nation's water quality. It is runoff from municipal storm drains, industrial sources and urban runoff from streets and gutters, parking lots, rooftops. Stormwater contains dirt, debris, chemicals and pollutants which flow into lakes, streams and rivers, eventually reaching the water table. These contaminate the water supply and have a negative effect on people, fish, animals and plants. The EPA requires that stormwater runoff be handled according to provisions of the Clean Water Act. Does this Spark an idea?
ETV Program and Crystal Stream
Runoff from parking lots carries gasoline and oil which can pollute the water supply.
In 1995, the Environmental Protection Agency (EPA) created a program to encourage the development of innovative technology to improve water quality. This Environmental Technology Verification (ETV) program selected several high priority areas, one of which was stormwater treatment. The development of stormwater management systems which could become Best Management Practices (BMP) was encouraged and three basic devices were identified. These were in-line filtration devices, hydrodynamic separators and in-drain filtration devices. Crystal Stream was a selected vendor of hydrodynamic separators and participates in the ETV Program.
Technology
The EPA encourages the development of devices to manage stormwater pollution.
Crystal Stream is a device that removes trash, debris and large particulates from stormwater. It consists of a reservoir, trash basket, oil collection buckets, baffles and absorbents enclosed in a pre-cast concrete vault. Trash floats to the top while heavier objects sink to the bottom. The vault remains full of water and a reservoir spans a creek or river from side to side and nearly to the bottom, blocking the outlet. As stormwater enters, it flows through a fine mesh in the trash basket which catches the debris and floating leaves, branches and grass, preventing them from sinking to the bottom and decomposing.
Oil-Grit Separator
The Crystal Stream system collects debris,sediment oil and hydrocarbons.
A separate chamber skims and collects oils, hydrocarbons and fluids that float on the water's surface. It captures 99 percent of all petroleum products and about 95 percent of grit, silt, heavy metals and some chemicals. It allows sediment to settle to the bottom while a trash collector on top captures Styrofoam cups, cigarette butts and miscellaneous debris.
Single Vault System
Urbanization has led to increased stormwater runoff.
This is a single reservoir concrete vault which provides 300 to 900 gallons of emergency spill protection. Water moves through its baffles and it captures debris and floating vegetative matter.
Twin Vault System
Crystal Stream vaults collect stormwater debris and polluting materials.
This system has a trash screening basket and two baffles in the front vault while another baffle and fiber filter are in the second. Water flows through the first vault where debris is collected and then through more baffles into the second. The concrete vaults can be arranged horizontally or vertically as needed.
Testing Process
Pollution levels are analyzed as part of the testing process.
The Crystal Stream installed at Griffin, Georgia was designed to receive stormwater runoff from drainage areas at a flow rate up to 17.5cfs. This is 7,850 gallons per minute (gpm). It can collect as much as 800 pounds of material per acre of drainage basin every year. Testing continued over 17 months, during which there were 15 qualified storms that produced runoff. The test results were evaluated and it was recommended that the trash baskets and collection devices be inspected every 90 days and maintained every 180 days or as conditions warranted.
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