Determination of Appropriate Monitoring Level(s) for a Stormwater Treatment Practice Determination of Appropriate Monitoring Level(s) for a Stormwater Treatment Practice

Determination of Appropriate Monitoring Level(s) for a Stormwater Treatment Practice.
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Level	When should I perform this assessment?	Advantages	Requirements/limitations	Recommended frequency	Can this be used to obtain a stormwater credit?
Visual inspection	Recommended for all practices	Quick and cost-effective	Available personnel. Does not necessarily identify causes of poor performance.	≥ 1x / year, at start of rainy season	No
Capacity testing	If there are suspected filtration rate problems with the practice, or to determine if the media has capacity for phosphorus removal	Applicable for practices of all sizes, quickly identify specific areas that require maintenance, less time and expense than monitoring	A Modified Philip-Dunne Infiltrometer is recommended for filtration rate testing.	Every few years	Consult with MPCA (Minnesota Pollution Control Agency) or regulatory agency to determine eligibility
Synthetic runoff testing	If there are suspected problems with filtration or pollutant removal, or to establish a baseline condition or baseline performance level	Controlled method to accurately measure drawdown time and/or pollutant removal efficiency	Testing will be limited by available water supply. Must be able to plug or measure all outflow paths other than filtration. Must be able to continuously measure water surface elevation in practice during test. Recommended for small stormwater treatment practices. May require authorization to conduct testing with targeted pollutants.	Every few years	Consult with MPCA or regulatory agency to determine eligibility
Monitoring	Goals include obtaining stormwater credits, assessing performance results and life of filter media, or complying with a permit or regulatory agency	Most comprehensive assessment technique and measures the response to natural rainfall events	Requires the most time, labor, and equipment of the four assessment techniques. Variations in weather, pollutant loading, and flows require correct and simultaneous operation of all instrumentation.	Continuously from construction of the IESF	Yes