Description   Mechanisms   Applications   Specifications   Plans   Water Quality   Maintenance   Resources   Back

Michigan Department of Environmental Quality, 2001.

Description

Three dimensional underground reservoirs utilizing porous media to allow infiltration of overland flow. This increases infiltration to groundwater in areas lacking space for other storm water management measures.

Natural Resources Conservation Service - Illinois Technical Resources, 2003.

Mechanisms

Overland flow is channeled and drained through stone aggregate and filter fabric designed to filter storm water through porous media at a specific rate. This increases the groundwater recharge while trapping pollutants within the trench.

California Stormwater BMP Handbook: New Development and Redevelopment, 2003.

Applications

• Useful in reducing runoff contamination from parking lots, paved highways, roofs, and other impervious surfaces.
• Regular maintenance required.
• Not for use with soils with low infiltration rates.
• Limitations in cold climates.
• Recommended for smaller areas due to clogging problems.
• Not for use with high pollution concentrations due to possible contamination of groundwater.
• Recommended for areas with limited space.
• Recommended for use with other storm water management practices.
• Requires pretreatment for suspended solids.

Detailed Specifications

Design Values*:
• Soil Infiltration ≥ 0.52.
• Trench bottom ≥ 4 feet above seasonal high water table.
• Design to handle flows for a 1-year storm event.
• Detention time of 6-72 hours, adjust this value for average time between storms in area of implementation.
• Storage volume equal to 0.5 inches of runoff per acre of impervious surface.
• 3-12 feet deep trench.
• Trench backfilled with 1.5-3 inch diameter washed aggregate.
• Pea gravel can be substituted in top foot of trench for increased sediment and pollutant removal.
• Install filter strip to control sediment runoff.
• Filter fabric surrounding sides and bottom of trench.
• Non-woven filter fabric 0.5-1 feet below the surface to prevent sediment from clogging the filter media.
• Trench bottom 3 feet below frost line.
• Install an observation well with an above ground cap.
• Trench bottom slope of 0%.
• Depress trench surface or install a berm on the down gradient side.
• Install pretreatment to remove ≥ 25% of sediment.
• Install bypass flow system for large storm water events.
• For more information visit:
  MDEQ Storm Water Management Guidebook,
  Metropolitan Council of Minnesota Urban Small Sites Best Management Practice Manual,
  US EPA Infiltration Trench Post-Construction Storm Water Management in New Development & Redevelopment.

*Note: Local governments may use different design values than those listed above, be sure to comply with any applicable laws and regulations.

Plans

Southeastern Wisconsin Regional Planning Commission, 1991 (Cited in United States Environmental Protection Agency. Storm Water Technology Fact Sheet: Infiltration Trench, 1999).

Schueler, 1987 (Cited in Metropolitan Council of Minnesota, 2003).

Schueler, 1987 (Cited in Metropolitan Council of Minnesota, 2003).

Water Quality

• Infiltration of runoff.
• Reduction in pollutant concentrations.
• Removal of up to:
• 90% of total sediments.
• 60% of total phosphorus.
• 60% of total nitrogen.
• 90% of various trace metals.
• 90% of bacteria.
• 90% of organics.
• 70-80% biochemical oxygen demand.
(The capacity to remove some pollutants will become exhausted with time.)

• For more information visit:
  US EPA Bioretention Storm Water Technology Fact Sheet,
  US EPA Bioretention Post Construction Storm Water Management in New Development & Redevelopment.

Maintenance

• Replace clogged aggregate as needed.
• Check trench twice a year to ensure proper functioning.
• Check observation well after every storm event for the first few months to examine drainage.
• Ponded water within the trench indicates removal and replacement of all aggregate.
• When ponding occurs, immediate maintenance is required.
• Pretreatment checked for proper functioning ≥ 2 times per year.

Resources

California Stormwater BMP Handbook: New Development and Redevelopment. January 2003. Infiltration Trench. TC - 10.

Menerey, B.E., Michigan Department of Environmental Quality. August 1999. Storm Water Management Guidebook Master Document. pp. 38-40.
http://www.michigan.gov/deq/0,1607,7-135-3313_3682_3716---,00.html (January 2006).

Michigan Department of Environmental Quality. 2001. Infiltration BMP’s.
http://www.michigan.gov/deq/0%2c1607%2c7-135-3313_3682_3714-13673--%2c00.html (January 2006).

Metropolitan Council of Minnesota. 2003. Infiltration Trenches. Urban Small Sites Best Management Practice Manual. pp. 3-169 - 3-180.
http://www.metrocouncil.org/environment/Watershed/BMP/CH3_STInfilTrenches.pdf (January 2006).

Natural Resources Conservation Service - Illinois Technical Resources. November 2002. Illinois Urban Manual: Practice Standard - Infiltration Trench.

Schueler, T. 1987. Controlling Urban Runoff: A Practical Manual for Planning and Designing Urban BMPs. Metropolitan Washington Council of Governments.

Southeastern Wisconsin Regional Planning Commission. 1991. Costs of Urban Nonpoint Source Water Pollution Control Measures. Technical Report No. 31.

United States Environmental Protection Agency. August 15, 2002. Infiltration Trench. Post-Construction Storm Water Management in New Development & Redevelopment.
http://cfpub.epa.gov/npdes/stormwater/menuofbmps/index.cfm (January 2006).

United States Environmental Protection Agency. September 1999. Infiltration Trench. Storm Water Technology Fact Sheet. EPA 832-F-99-019.
http://www.epa.gov/owmitnet/mtb/infltrenc.pdf (January 2006).