What process must occur after the excavation of an infiltration basin?

The correct answer is that filter fabric must be installed on the base of the infiltration basin. This step is crucial for several reasons.

Filter fabric serves as a barrier that prevents the migration of fine soil particles while allowing water to permeate freely into the basin. By doing so, it helps maintain the structural integrity of the infiltration basin and ensures that its function—allowing stormwater to infiltrate the ground—is not compromised by sediment build-up. Without this protective layer, sediments could clog the infiltration zone, leading to reduced performance of the basin and potential failure in managing stormwater.

The other processes listed do not align with best practices following the excavation of an infiltration basin. Filling the excavation immediately would negate the purpose of creating the basin, while the installation of concrete footings is not typical for infiltration systems, which are usually designed to be permeable. Lastly, although drainage pipes may be used in some stormwater management systems, they are not a necessary step directly following the excavation of an infiltration basin, especially considering the intent of allowing infiltration into the soil.