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→Natural or Simulated Storm Event Testing
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.
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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If the primary objective of natural or simulated storm event testing is only to confirm that conveyances are delivering stormwater to the BMP, this is easily done by observing where water flows as it is delivered to the CDA. Prior to and after the release of water, measurements of water level in monitoring wells should be made and recorded to be able to detect whether or not flows are reaching the water storage portion of the BMP if it cannot be observed visually. Manual water levels measurements can be taken by lowering a rod, level tape or string with a weight on the end into the well until the bottom is reached and measuring the height of water present from the maximum water level indicated on the device.
* Water level can also be measured using a pressure transducer installed to just above the bottom of the well and set to continuously record water level at 1 minute intervals. For BMPs that contain sub-drains that can be accessed and visually inspected, observations should be made to determine if flow from the sub-drain pipe occurs following delivery of water to the BMP.
===Standard Equipment Used===
Equipment needed for natural or simulated storm event testing will vary depending on the BMP type, objectives of testing and the chosen method but can include the following:
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* Water source of sufficient quantity (e.g., water truck, fire hydrant, truck mounted cistern)
* Safety apparel (steel toed boots)
* Safety cones or barriers (for restricting access when testing permeable pavements)
* Clipboard, inspection field data forms, pens
* Camera
* Water level tape or dip stick
* Measuring tape
* Surface ponding well
* Sub-surface water storage reservoir monitoring well
* Pressure transducers data logger (optional ,for detecting water level change in sub-drains)
* Hydrant coupling kit (for connecting to fire hydrant)
* Magnetic flow meter and data logger (for measuring quantity of water delivered to the BMP)
* Pipes (to distribute flow to the CDA or BMP itself)
* Pipe couplings (to connect water truck or fire hydrant hose/nozzle to flow meter and distribution pipes);
* Pick for opening manholes or catch basin grates;
* Multi-gas sensor (for safe access of manholes or catch basins)}}
===Acceptance Criteria===
Acceptance criteria for LID BMP drainage performance for both natyural and simulated storm event testing:
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# Water flows into the BMP as intended;
# For [[bioretention]], [[bioswales]] and [[enhanced swales]], the surface water storage reservoir (i.e., surface ponding) fully drains within 24 hours of the end of the storm;
# For [[bioretention]] and [[bioswales]], the filter bed surface infiltration rate ≥25 mm/h and ≤203 mm/h, or consult manufacturer or vendor for an acceptable range specific to the filter media product.
# For [[enhanced swales]], [[vegetated filter strips]] and [[Absorbent landscapes|Absorbent landscapes / soil amendment areas]], the surface infiltration rate ≥15 mm/h and ≤203 mm/h, or consult manufacturer or vendor for an acceptable range specific to the topsoil product.
# For newly constructed BMPs (i.e., Assumption inspection), the active sub-surface water storage reservoir volume drains within 48 to 72 hours of the end of the storm and sub-drain peak flow rate is within +/- 15% of design specification; and,
# For aged BMPs (i.e., Performance Verification inspections), active sub-surface water storage reservoir volume drains within 48 to 96 hours of the end of the storm and sub-drain peak flow rate is within +/- 15% of design specification.}}
For further information regarding natural and simulated storm event testing, acceptance criteria per LID BMP type and associated testing tools and protocols scroll down to the embedded 2016 guide below.
==Continuous Monitoring==
==Continuous Monitoring==