Water Quality Units

Water Quality Units

Standards for storm water quality will necessarily vary by location and land use. The most targeted sources of runoff pollution are paved areas in urban and industrial sites. These are generally small (<1 acre), with high traffic loads, such as parking lots and gas stations, that generate significant concentrations of contaminant particles and hydrocarbons.

Because of land constraints, ADS underground Water Quality Units have become an increasingly efficient solution for treating storm water. These durable, lightweight structures have been specifically designed for fast installation and easy maintenance.

ADS Water Quality Units

Design Principles

Available in 36″ through 60″ diameters, ADS Water Quality Units  are modified sections of N-12® pipe with weir plates at certain locations and heights to remove high percentages of sediment and oils from the first flush of a storm event. They can be installed at any point in the subsurface drainage system, and are ideally suited to treat “hot spots” in existing storm water lines.

The unit is designed using the fundamental principles of Stoke’s Law and a standard orifice outlet control. The settling velocity of a particle is calculated based on the smallest particle to be removed (standard units offer a choice of 140 or 200 sieve size). The outlet orifice is sized to release a typical first flush discharge, and to redirect any excess flow to a bypass piping system installed with the unit.

Design Variations

The standard models will provide efficient removal of pollutant particles and hydrocarbons for the majority of site conditions. For unusual conditions, ADS can recommend a system combining a variety of sizes and configurations.

ADS can also incorporate other pollutant control features into the drainage network. These include inlet protection devices, trash screens, filtration systems, and a large selection of sediment prevention products from our strategic partner, SI® Geosolutions.

  • Laboratory tests have shown an 80% TSS removal rate.
  • Removes floatable debris such as oils and greases.
  • Available in 36″ through 60″ diameters.
  • Lightweight High Density Polyethylene (HDPE) unit installs easily with a minimum of manpower. Heavy cranes are not necessary to install the unit.
  • Each unit is fitted with access risers for easy inspection and maintenance of the sediment and oil chambers.
  • The unit is fitted with access risers for easy inspection and maintenance of the sediment and oil chambers.
  • The unit is inexpensive because the design is simple and there are no moving parts.
  • The bypass system prevents re-suspension of captured solids by diverting water flows greater than the first flush.
  • HDPE resists abrasion and chemicals found in storm water and in the surrounding soil.