Table 3.
Long-Term Hydrologic Impact Assessment (L-THIA) Low Impact Development (LID) spreadsheet inputs and outputs measuring master plan performance.
| Summary | ||||
| Land Use | Hydrologic Soil Group | Pre-Developed | Post-Developed W/o LID | Post-Developed with LID as Proposed |
| HD Residential 1/8 acre | C | 94.18 | 28.54 | 15.69 |
| Industrial | C | 4.46 | 4.09 | - |
| LD Residential 1/2 acre | C | 53.21 | 32.24 | 20.95 |
| Grass/Pasture | C | 55.17 | 130.46 | - |
| Commercial | C | - | 5.99 | 2.39 |
| Water | C | - | 5.7 | - |
| Percentage Impervious | ||||
| Land Use | Default | Adjusted | ||
| Residential 1/4 acre | 38 | - | ||
| Residential 1/8 acre | 65 | 65 | ||
| Residential 2 acre | 12 | - | ||
| Residential 1 acre | 20 | - | ||
| Residential 1/2 acre | 25 | 25 | ||
| Commercial | 85 | 85 | ||
| Industrial | 72 | 72 | ||
| Avg. Annual Runoff Volume (Acre-Ft) | ||||
| Land Use | Current | Post-Developed with LID as Proposed | ||
| HD Residential 1/8 acre | 103.57 | 29.94 | ||
| Industrial | 5.21 | 4.77 | ||
| LD Residential 1/2 acre | 29.67 | 17.98 | ||
| Grass/Pasture | 20.42 | 48.29 | ||
| Commercial | 0 | 9.01 | ||
| Water | 0 | 0 | ||
| Total Annual Volume (acre-ft) | 158.88 | 110.01 | ||
| Nonpoint source pollutant results | ||||
| Pre-Developed | Post-Developed with LID as Proposed | |||
| Nitrogen (lbs) | 715 | 377 | ||
| Phosphorous (lbs) | 209.556 | 84 | ||
| Suspended Solids (lbs) | 15,799 | 7633 | ||
| Lead (lbs) | 3.218 | 2.345 | ||
| Copper (lbs) | 3.496 | 2.725 | ||
| Zinc (lbs) | 31.333 | 16.789 | ||
| Cadmium (lbs) | 0.354 | 0.277 | ||
| Chromium (lbs) | 1.277 | 1.595 | ||
| Nickel (lbs) | 2.925 | 1.701 | ||
| Biochemical Oxygen Demand (BOD) (lbs) | 9483 | 4141 | ||
| Chemical Oxygen Demand (COD) (lbs) | 18,617 | 9905 | ||
| Oil & Grease (lbs) | 658 | 481 | ||
| Fecal Coliform (millions of coliform) | 33,681 | 13,333 | ||
| Fecal Strep (millions of coliform) | 92,809 | 35,607 | ||