Try this Example on your own: Determine the runoff curve number for a $25-$year and $100-$year

storm event on the following site:

The soil is composed of $40\%$ sand, $30\%$ silt and $30\%$ clay.

Step $1$: Determine the Soil Group

Step $2$: Look up the CN Values

Step $3$: Determine the CN for $25$ and $100$ year for the site