Oldcastle Infrastructure Written

Written

Course Information
When it comes to stormwater mitigation, the United States is wrestling with urban flooding and epic droughts, and both come with a heavy price tag. Underground infiltration galleries and drywells are stormwater infiltration best management practices (BMPs) that effectively reduce runoff and help restore natural hydrology by promoting shallow and deep infiltration to recharge groundwater resources.

Such solutions must meet the needs of Municipal Separate Storm Sewer Systems (MS4) and the National Pollutant Discharge Elimination System (NPDES) permit programs, including Total Maximum Daily Load (TMDL) pollution load reduction requirements.

In its 2021 report card, the American Society of Civil Engineers (ASCE) gave America’s stormwater infrastructure a ‘D’ grade. Polluted runoff from pavement entering water bodies has impaired nearly 600,000 miles of rivers and streams as well as more than 13 million acres of lakes, reservoirs and ponds. Urban flooding causes $90 million in annual damages, yet there’s an annual federal funding gap of $8 billion to comply with current regulations.

Author
Kathryn Thomason and Bill De JongLearning Objectives
By the conclusion of this article, the reader should be able to understand:

• The significance of deep infiltration and drywells as stormwater mitigation

• What constitutes a drywell and how it works in stormwater mitigation

• How drywells are regulated

• How to design a drywell for optimal outcomes

• Circumstances under which drywells would not be indicated in stormwater mitigation design