Design of Terminal Exfiltration Trenches for Stormwater Management on Roadways

Abstract Stormwater management regulations for roadways typically allow for pavement or shoulder encroachment of runoff from rainfall events with a given return period, and also require retention of a given water quality volume. Conventional designs of terminal exfiltration trenches (ETRs) that handle roadway runoff do not account for encroachment storage, and they seldom consider all possible event durations for a given return period. To address these gaps, a novel methodology is presented that meets both the encroachment and water quality retention constraints. The methodology applies to both conventional ETRs and partially submerged ETRs that are widely used in the coastal areas of South Florida. Design examples are provided for both cases.