Changes

Final inspection requirements are in-place to ensure that a final site-wide inspection is performed and allow for mitigation to occur before the contractor is relieved of responsibility. Final certifications are performed by knowledgeable personnel, such as the design engineer, who are qualified to ensure that LID features are operating as intended. This stage is critically important, as it is the last opportunity for issues to be resolved before the property owner assumes responsibility of the practice. The University of Minnesota and the Minnesota Pollution Control Agency recommend four (4) levels of inspection for final inspections of LID infiltration and filtration practices. The level of inspection, or combination of tests, that is selected is dependent on the goals of the assessment and feasibility of each inspection.

Final inspection requirements are in-place to ensure that a final site-wide inspection is performed and allow for mitigation to occur before the contractor is relieved of responsibility. Final certifications are performed by knowledgeable personnel, such as the design engineer, who are qualified to ensure that LID features are operating as intended. This stage is critically important, as it is the last opportunity for issues to be resolved before the property owner assumes responsibility of the practice. The University of Minnesota and the Minnesota Pollution Control Agency recommend four (4) levels of inspection for final inspections of LID infiltration and filtration practices. The level of inspection, or combination of tests, that is selected is dependent on the goals of the assessment and feasibility of each inspection.<br>

'''Visual Inspection (Level 1)'''

'''Visual Inspection (Level 1)'''<br>

This qualitative method is low cost and requires minimal effort to conduct. Visual inspection should be used as an initial step to determine if the LID practice is operating properly. Visual inspections can be performed during dry weather and wet weather to identify situations where water is ponding for longer than intended (24 hours).

This qualitative method is low cost and requires minimal effort to conduct. Visual inspection should be used as an initial step to determine if the LID practice is operating properly. Visual inspections can be performed during dry weather and wet weather to identify situations where water is ponding for longer than intended (24 hours).<br>

'''Surface Infiltration Capacity Testing (Level 2)'''

'''Surface Infiltration Capacity Testing (Level 2)'''<br>

Using infiltrometers or permeameters to measure the hydraulic conductivity at several locations in the LID feature at various times of year can quantitatively verify that the practice can perform as intended.

Using infiltrometers or permeameters to measure the hydraulic conductivity at several locations in the LID feature at various times of year can quantitatively verify that the practice can perform as intended.<br>

'''Synthetic Runoff Testing (Level 3)'''

'''Synthetic Runoff Testing (Level 3)'''<br>

To perform the test, the practice must be filled with synthetic runoff and the change in water level must be monitored. Using clean water from a fire hydrant or water truck, synthetic runoff testing can measure the performance of an LID feature in a controlled environment. For this test to be feasible, a series of conditions must be met:

To perform the test, the practice must be filled with synthetic runoff and the change in water level must be monitored. Using clean water from a fire hydrant or water truck, synthetic runoff testing can measure the performance of an LID feature in a controlled environment. For this test to be feasible, a series of conditions must be met:

*A water supply that can deliver the required discharge and volume requirements

*A water supply that can deliver the required discharge and volume requirements

*No precipitation must be expected for 48 hours

*No precipitation must be expected for 48 hours

*Outflow paths must be temporarily plugged or measured (aside from infiltration)

*Outflow paths must be temporarily plugged or measured (aside from infiltration)

*The water surface elevation can be measured throughout the test

*The water surface elevation can be measured throughout the test<br>

'''Long-term Monitoring (Level 4)'''

'''Long-term Monitoring (Level 4)'''<br>

Monitoring offers a comprehensive approach to assessing peak flow reduction and water volume reduction. These reductions can be quantified by completing a water budget during natural storm events, specifically through the measurement of inflow and outflow. Long-term monitoring is especially recommended if the LID feature that is the subject of the test is the first of its kind in its given jurisdiction, if geologic conditions pose a concern, or if the feature is being implemented to protect sensitive and significant natural features. It is important to recognize, however, that the unpredictability of natural storm events can lead to inaccuracies in data collection. Furthermore, long-term monitoring generally has the highest cost of the four levels of monitoring.

Monitoring offers a comprehensive approach to assessing peak flow reduction and water volume reduction. These reductions can be quantified by completing a water budget during natural storm events, specifically through the measurement of inflow and outflow. Long-term monitoring is especially recommended if the LID feature that is the subject of the test is the first of its kind in its given jurisdiction, if geologic conditions pose a concern, or if the feature is being implemented to protect sensitive and significant natural features. It is important to recognize, however, that the unpredictability of natural storm events can lead to inaccuracies in data collection. Furthermore, long-term monitoring generally has the highest cost of the four levels of monitoring.