Subsurface Infiltration Vaults: Puttin' Water In It's Place

Recent EPA regulations require the infiltration of the first inch of rainfall from each storm event occurring on all new development sites. Subsurface infiltration vaults are an effective strategy for increasing residential stormwater infiltration according to those regulations. These vaults are an alternative to common Best Management Practices (BMP) such as rain gardens and green roofs. The vaults are corrugated plastic arches with front and side walls extending from the arch to the soil surface. These arches will be placed in a trench and covered with gravel and cement. This design improves upon existing subsurface vault designs by enhancing applicability on slopes and aiding in site construction. The surface cement will act as sidewalks and driveways, thus incorporating those installation costs into site stormwater management and reducing overall construction costs. To improve applicability on slopes, the vault design is modular with the inclusion of partitioning walls which function as check dams between modules. Individual aspects of this design were analytically and physically tested to ensure feasibility. These aspects include slope applicability and the structural stability. A series of inlet vaults included in the vault system will accept surface runoff via surface grates, accept roof downspout water, retain sediment, and allow for easy periodic removal of sediment.