The terms “high-rate biofiltration” and “runoff reduction” aren’t often used in the same sentence. The engineering community has a preconceived notion that a high-rate biofilter with an underdrain (like Filterra®) can’t provide runoff reduction benefits because the stormwater it treats moves through the practice too quickly. However, with the proper design considerations, we can maximize the capability of a high-rate biofilter to provide appreciable runoff reduction. 

In civil engineering and stormwater management, a design storm refers to a specific rainfall event defined and described by the statistical likelihood of the event occurring in a given rainfall year. Design storms are used as a standard for designing and evaluating stormwater infrastructure. For example, local stormwater standards commonly call out the 1, 2, 5, 10, 50, and 100-year storm events and the water quality storm event for a given geography, each of which plays a role in the design and implementation of stormwater infrastructure.

Stormwater runoff is a significant source of water pollution, carrying various pollutants from urban areas into natural water bodies. Most stormwater treatment efforts have focused on the capture of total suspended solids. Still, significant pollutant loads can be attributed to dissolved pollutants, such as heavy metals, nutrients, and organic compounds, which can have detrimental effects on aquatic ecosystems and public health.

Where are you buying structural backfill these days? Is what you need readily available, or are you looking outside your area and/or waiting an extended time for delivery? With available land space continuing to decrease, stormwater detention/retention is commonly being designed underground. The current construction boom and increasing detention volume requirements have made rock scarce and expensive in many parts of the country.

We are an industry of abbreviations and acronyms. The terms we use daily can sometimes hold a general or broad meaning in our minds, but the actual definition