New System Provides Stormwater Treatment, Infiltration in one Structure

With hundreds of installed projects ranging from small parking lots to large industrial applications, the Stormwater Management StormFilter® from CONTECH Stormwater Solutions has been in use for over 10 years, removing TSS, soluble heavy metals, total nutrients, and oil and grease. The company recently introduced a new configuration to the product line, the DryWell StormFilter.

When sites do not have a convenient outfall, storm sewer, or combined sewer to collect stormwater runoff, it is usually infiltrated to groundwater. Dry wells, also known as injection wells, are often used for this application. In this simple design, stormwater enters the unit through one or more entry pipes or channels at its top, and then is discharged through a number of small exit openings at the sides and bottom. Without treatment, these flows carry pollutants that can contaminate groundwater. In addition, the life of the infiltration device is impacted by pollutants that collect in the surrounding soil and impede infiltration.

Dry wells are an accepted way to provide infiltration of stormwater to groundwater and they are growing in popularity. As the use of dry wells continues to grow, many regulatory agencies are implementing strict pretreatment standards for all new dry wells. In addition, a requirement to retrofit existing dry wells with a pretreatment device is becoming common. The DryWell StormFilter was developed to meet these requirements.

The new technology is designed to treat conveyed flow or sheet flow up to 0.24 cfs. Engineered to simplify site design by providing treatment and infiltration in one structure, the DryWell StormFilter can reduce the total number of structures and the amount of pipe required for a site’s stormwater management system. This lowers the associated design, capital and installation costs. Large areas can be treated by installing multiple units.

The system is available in 48-, 60- and 72-inch pre-cast manhole top sections that are designed to be stacked on dry well infiltration risers. The units arrive fully assembled and ready to install, including an integrated concrete deck for the StormFilter cartridges. The system can also be retrofitted into existing 48-inch manhole dry wells.

Installation is completed in three steps, and typically takes four to six hours. First, the StormFilter deck needs to be installed. Next, the infiltration holes in the riser sections above the deck need to be grouted. The last step is to install the cartridges and overflow standpipe.

As with all StormFilter products, the new DryWell StormFilter is engineered to operate for one year before requiring maintenance (for new construction applications). In many cases this interval is even longer. Maintenance of the cartridges and the dry well sump (which can be accessed through the overflow riser) can be performed by CONTECH, or a cartridge exchange program can be used by owners who wish to perform the maintenance themselves.

CONTECH Stormwater Solutions Inc. is a provider of stormwater treatment and detention/retention solutions. For more information on the company and its products, visit www.contechstormwater.com