Anika Hall_Research 1.1_Stormwater Management

“When stormwater is absorbed into the soil, it is filtered and ultimately replenishes aquifers or flows into streams and rivers. However, when heavy rainwater hits, ground saturated by water creates excess moisture that runs across the surface and into storm sewers and road ditches. This water often carries debris, chemicals, bacteria, eroded soil, and other pollutants, and carries them into streams, rivers, lakes, or wetlands.

In urban and developed areas, impervious surfaces such as pavement and roofs prevent precipitation from naturally soaking into the ground. Instead, water runs rapidly into storm drains, sewer systems and drainage ditches and can cause flooding, erosion, turbidity (or muddiness), storm and sanitary sewer system overflow, and infrastructure damage. However, stormwater design and ‘green infrastructure’ capture and reuse stormwater to maintain or restore natural hydrologies.” (EEC Environmental, 2023)

The way in which the effectiveness of a local stormwater management system can be measured depends on the type of stormwater management system. In Eugene, common stormwater management practices used include stormwater ditches and drains connecting to the wastewater treatment plant, and localised retention basins and bioswales. A few potential parameters which could be measured to determine the effectiveness of a site’s stormwater management system include:

• Water Quality
  • This important for both stormwater infiltrating onsite which may contaminate local groundwater, as well as stormwater discharging offsite which will carry pollutants to the water treatment plant and/or downstream creeks/rivers.
• Runoff Quantity
  • This is primarily applicable to the amount of stormwater draining offsite to the water treatment plant, and which may contribute to storm surge in rivers as well as combined sewer overflows.
• Onsite Infiltration Rate
  • This is primarily applicable in assessing the effectiveness of local infiltration methods, such as bioswales or infiltration ponds.

Ideally site-specific precipitation would also be measured along with each of the parameters listed above.

References:

EEC Environmental. 2023. What Is Stormwater Management and Why Is It Important? available online at: https://eecenvironmental.com/what-is-stormwater-management/