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→Natural or Simulated Storm Event Testing
==Natural or Simulated Storm Event Testing==
==Natural or Simulated Storm Event Testing==
[[File:Simulated storm event.PNG|500px|thumb|Example of a simulated storm event test being conducted in a [[bioswale]] with a large water truck. (Source: TRCA, 2016)<ref>Toronto and Region Conservation Authority (TRCA). 2016. Low Impact Development Stormwater Management Practice Inspection and Maintenance Guide. Prepared by the Sustainable Technologies Evaluation Program. Vaughan, Ontario. https://sustainabletechnologies.ca/app/uploads/2016/08/LID-IM-Guide-2016-1.pdf</ref>]]
For LID BMPs that receive stormwater via conveyances like gutters, concrete [[inlets]] and leader pipes from roofs or [[pretreatment|catchbasins]] (i.e., [[bioretention]] and [[bioswales]], [[enhanced swales]], [[soakaways]], [[infiltration trenches]], [[exfiltration trenches]] [[infiltration chambers]] and [[soil cells]]) it is critically important to confirm that these conveyances have been designed and constructed properly. If the conveyances are obstructed or improperly graded or constructed, the BMP may not receive flows from their CDA or a significant quantity of stormwater may by-pass treatment. This is particularly important for underground BMPs where inlets are not visible from the surface. Therefore, confirming that these types of BMPs actually receive stormwater from their CDA should be a part of Assumption and Verification inspections.
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The simplest approach to confirming that conveyances to LID BMPs are constructed properly and functioning well is through observation of the path of water flow and measuring water level in the BMP during a natural storm event. If timelines for completing inspections cannot be coordinated to coincide with a natural storm event, an alternative approach is to simulate a storm event over the CDA by directing water onto it through the use of a water tanker truck or fire hydrant while observing conveyances and measuring water level in the BMP. Such testing not only confirms that conveyances to the BMP are functioning properly but also helps to confirm the size of the CDA (i.e., that site grading is correct) and that sub-drain systems are functioning properly.
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Natural or simulated storm event testing can also be undertaken to confirm that an LID BMP drains at an acceptable rate. Designing such tests is much more involved and requires the deployment of specialized field monitoring equipment like continuous water level loggers (i.e., pressure transducers) in monitoring wells, flow measurement apparatuses (e.g., area-velocity sensors) in sub-drain or outlet pipes and rain gauges, in addition to staff familiar with the use and calibration of such equipment and the processing and analysis of the data. See the "Continuous Monitoring Section" below which provides guidance on the utility and design of continuous monitoring programs along with key references for further reading.
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==Continuous Monitoring==
==Continuous Monitoring==