$1.$Use Stokes Law to determine the trapping efficiency of the detention pond from question $1,$ Homework Assignment $6.$ For water quality analysis, a $1$ year storm is often used and rerun the Hydrocad model for a $1$ year storm to obtain discharge leaving the pond and peak water elevation of the pond. Use Stokes law to determine the smallest micron size particle that is trapped in your pond. Please note that the timing for settling a particle is calculated from the peak water elevation to the invert of the outlet. We assume once the particle is below the invert outlet it will keep settling to the bottom of the pond. Hint: You would compare the settling time calculated from stokes law of various particle sizes to timing calculated from Volume of Pond Storage above the pipe invert $($V$)/$ Outlet Discharge $($Q$).$

$2.$A storm sewer has measured TSS concentrations at the three locations $($A$,$ B$,$ and C$)$ shown in the picture below. Provide the total Flow $($Q$),$ TSS Mass Flow Rate, and TSS Concentration at the outlet of the pipe system. The secondary system is in the photo and described below.

$3.$ The annual rainfall in Madison is about $35$ inches. Using the simple method find the annual mass of oil $($kg$/$yr$)$ from a $10-$acre commercial area with a runoff coefficient of $0\mathrm{.}8.$ The event mean concentration is $4\mathrm{.}0$ mg$/$l$.$

$Q_A=24\frac{\text{I}}{s},Q_B=18\frac{\text{I}}{s},Q_C=30\frac{\text{I}}{s}$

$TS{S}_A=87m\frac{g}{l},TS{S}_B=104m\frac{g}{l},TS{S}_C=45m\frac{g}{\text{I}}$

$4.$ Find the annual mass of TSS $($lb$/$yr$)$ from $10$ acres of agriculture and residential area in Madison. Assume rainfall of $35$ inches. Compare the differences.