In Example 3, we designed a regional detention pond for a 29-acre residential site to manage water quality and reduce peak runoff flows. Example 4 introduced Low Impact Development (LID) controls to decrease runoff volume. Example 5 modeled total suspended solids (TSS) but didn’t consider LID or pond TSS removal. Now, we’re extending these models to include TSS removal in both LIDs and the pond. Figure 6-1 shows the study area with LIDs and the resized pond (SU2) due to LID’s impact, reducing the required water volume from 24,162 ft³ (Example 3) to 17,524 ft³.
The storage unit’s shape and outlet structures were modified to meet the new WQCV requirements and adhere to the design criteria from Example 3, which includes a 40-hour drawdown time for the WQCV and mitigation of peak flows during 2-, 10-, and 100-year storms. Tables 6-1 and 6-2 compare the storage curve and outlet structure dimensions between the Example 3 pond without LIDs and the one in this example with LIDs. Figure 6-2 provides a visual overview of the outlet placements.