In Examples 1 and 2, we estimated runoff for a 29-acre residential development without any controls. Now, we’ll assess the impact of using infiltration trenches and filter strips, common Low Impact Developments (LIDs).

Four infiltration trenches will be placed on each side of the east-west street in the upper part of the area, and filter strips will manage runoff from specific lots. Unlike Example 3, where a detention pond aimed to match pre-development discharge, these LIDs focus on general runoff reduction to meet sustainability goals. We’ll analyze their performance during 2-, 10-, and 100-year storms.

Figure 4-1
Source: “Storm Water Management Model Applications Manual”