Methods for calculating pollutant reductions (credits) for street sweeping Methods for calculating pollutant reductions (credits) for street sweeping

This page provides a summary of methods that can be used to quantify pollutant reductions from street sweeping.

Approved methods for calculating pollutant reductions from street sweeping

These methods are approved for calculating pollutant reductions. Guidance for calculating pollutant reduction is contained in this manual.

• Dry mass measurement. This method involves weighing the total (wet) mass of street sweepings and collecting samples for calculating the dry mass as a percent of total (wet) mass. The dry mass represents total solids collected. To calculate total phosphorus, dry mass is multiplied by a conversion factor.
• Wet mass measurement. This method involves weighing the total (wet) mass of street sweepings and multiplying by conversion factors to calculate total solids or total phosphorus.
• Organic matter measurement. This method is applicable for calculating phosphorus reductions and is similar to the procedure for dry mass measurement.
• Modeling. WINSLAMM and P8 are acceptable models for calculating pollutant reductions from street sweeping.
• Empirical methods. Empirical methods may be based on factors such as miles swept, number of times swept in a year, and type of sweeper equipment. Some empirical methods are summarized in Survey of street sweeping crediting approaches. Empirical methods are acceptable but typically provide small reductions in pollutant loading.

Methods that are not approved but may be acceptable for calculating pollutant reductions from street sweeping

The following methods may be acceptable if appropriate protocol are followed. This manual does not provide guidance for applying these methods. Pollutant reductions calculated with these methods must be approved by the MPCA if used for permit compliance.

• Direct measurement of phosphorus. This method applies to phosphorus measurement and will typically involve sending samples to approved laboratories to determine phosphorus content of sweeping material.
• Volume. Calculating pollutant reduction based on volume of material collected requires establishing relationships between volume and dry mass. The methods and procedures for establishing these relationships must be fully documented for permit compliance.
• Modeling. Models other than WINSLAMM and P8 may be acceptable, but MPCA must be contacted if the model results are used for permit compliance.
• Empirical methods. Empirical methods other than those summarized in Survey of street sweeping crediting approaches may be acceptable. MPCA must be contacted for permit compliance.