File:MIDS screen shot 2.png

File:MIDS screen shot 2.png

This screen shot provides output data for the following permeable pavement design:

• surface area = 3000 square feet;
• soil porosity = 0.40
• underdrain located 0.2 feet above the underlying soil;
• HSG C;
• drawdown time of 48 hours; and
• no contribution from adjacent impervious surfaces or upstream BMPs.

Output includes the following:

• Annual post-development TSS load, in pounds = EMC * surface area of peremable pavement = 54.50mg/L * 3000 square feet * conversion factor = 22 pounds
• Annual TSS load received from upstream BMP, in pounds = 0 since there is no contribution from impervious surfaces;
• Annual total TSS received by BMP = sum of the previous two terms = 22 pounds
• TSS removed via non-volume reduction treatment = 74%
• Total TSS removed via volume reduction and other treatment, expressed as a percent. This number is calculated by multiplying 74% by the fraction of infiltrated water passing through the underdrain by the fraction passing below the underdrain = 92% in this example;
• Annual TSS reduction in pounds = the above term multiplied by the total TSS received = 0.92 * 22 pounds = 20 pounds; and
• Remaining TSS load = Annual TSS received by BMP minus Annual TSS reduction = 2 pounds