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Inspection and Maintenance: Rainwater Harvesting (view source)
Revision as of 21:14, 12 August 2022
, 2 years agono edit summary
{| class="wikitable" style="width: 900px;"
{| class="wikitable" style="width: 900px;"
|+'''Testing Indicators Framework - Green Roofs'''
|+'''Testing Indicators Framework - Rainwater Harvesting Systems'''
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!<br>'''Component'''
!<br>'''Component'''
{| class="wikitable" style="width: 1000px;"
{| class="wikitable" style="width: 1000px;"
|+'''Bioretention/Swales: Construction Inspections'''
|+'''Rainwater Harvesting Systems: Construction Inspections'''
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!<br>'''Construction Sequence Step & Timing'''
!<br>'''Construction Sequence Step & Timing'''
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==Routine Maintenance - Key Components and I&M Tasks==
Regular inspections (twice annually, at a minimum) done as part of routine maintenance tasks over the operating phase of the BMP life cycle to determine if maintenance task frequencies are adequate and determine when rehabilitation or further investigations into BMP function are warranted.
Table below describes routine maintenance tasks for [[rainwater harvesting]] practices, organized by BMP component, along with recommended minimum frequencies. It also suggests higher frequencies for certain tasks that may be warranted for cisterns that receive flows from large roof drainage areas or roofs with mature [[trees]] near them. Tasks involving removal of debris, sediment and trash may need to be done more frequently in such contexts.
{|class="wikitable" style="width: 1280px"
|+'''Rainwater Harvesting: Key Components, Descriptions and Routine I&M Requirements'''
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!style="width: 500px"|Component
!style="width: 1500px"|Description
!style="width: 1500px"|Inspection & Maintenance Tasks
!style="width: 500px"|<span style="color:green">('''Pass''')</span> Photo Example
!style="width: 550px"|<span style="color:red">('''Fail''')</span> Photo Example
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|'''[[Rainwater harvesting: Sizing and modeling|Contributing Drainage Area (CDA)]]'''
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Roof area(s) from which runoff directed to the BMP originates.
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*Remove natural debris and sediment annually to biannually;
*Trim back tree boughs that hang over the roof area to reduce maintenance needs.
|[[File:Pass.PNG|300px|thumb|center|CDA has not changed in size or land cover. Sediment, trash or debris is not accumulating and point sources of contaminants are not visible.]]
|[[File:Fail bio.PNG|280px|thumb|center|Size of the CDA has changed from design assumptions. A point source for contaminants is visible (i.e. lack of sediment controls on adjacent construction site). (Photo Source: North Carolina Cooperative Extension)]]
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|'''[[Pretreatment]]'''
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Devices prevent debris and sediment from entering the BMP. Includes eavestrough or downspout screens, first flush diverters or filters on pipes leading to or from the cistern. Reduce the risk of obstructing [[inlets]], intakes or [[overflows|overflow outlet]] [[pipes]] and excessive sediment accumulation.
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*Remove trash, debris and sediment biannually to quarterly or when the device sump is half full;
*Measure sediment depth or volume during each cleaning, or annually to estimate accumulation rate and optimize frequency of maintenance.
|[[File:Pretreatment pass bio.PNG|310px|thumb|center|[[Forebay]] is free of sediment, trash and debris and recently maintained. The large stones in the feature are used to slow down and spread out inflowing water into the feature and they remain well arranged and in place.]]
|[[File:Pretreatment fail bio.PNG|290px|thumb|center|An erosion gully occurring where bare soil is starting to become visible on the [[Vegetated filter strips|grass filter strip]] pretreatment feature at the inlet, thus indicating it is not effectively slowing and spreading out the inflow of stormwater to the BMP.]]
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|'''[[Inlets]]'''
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[[Pipes]] connected to eavestroughs or roof drains that deliver water to the BMP. May also include a pipe connected to the municipal water supply line for maintaining cistern water level during dry weather.
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*Check for obstructions and remove any debris or sediment annually to biannually;
*For outdoor above-ground cisterns and rain barrels, inlets need to be disconnected in the late fall/early winter, prior to the onset of freezing air temperatures;
*Reconnect outdoor above-ground cisterns to the roof drainage area in the spring once air temperature remains above freezing.
|[[File:Inlets bio pass.PNG|285px|thumb|center|There is no evidence of damage or displacement of the inlet structure that would prevent runoff from freely entering the BMP.]]
|[[File:Inlets bio fail.PNG|300px|thumb|center|Accumulated sediment and vegetation is preventing stormwater from entering the BMP. Sediment on the pavement surface in front of the inlet indicates ponding is also occurring]]
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|'''Access Hatch'''
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Hatch, manhole or lid that provides access to the interior of the water storage structure.
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*Inspect for damage, obstruction and accessibility annually.
|[[File:Perimeter bio pass.PNG|305px|thumb|center|The footprint area of the bioretention cell does not significantly deviate from the final design and should not negatively affect its stormwater management treatment performance.]]
|[[File:Perimeter bio fail.PNG|300px|thumb|center|The footprint area of the BMP is significantly smaller than what was specified in the final design of this example and differ greater than the recommended SWM criteria requirements (>10%).]]
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|'''[[Rain barrels|Cistern or rain barrel]]'''
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The water storage structure (e.g., concrete vault, fiberglass, plastic or metal tank, rain barrel).
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*Inspect for damage or leaking annually;
*Drain and remove accumulated sediment as needed (annually at a minimum).
|[[File:Filter bed bio pass.PNG|295px|thumb|center|There are no erosion gullies or bare soil areas on the filter bed surface and mulch cover remains in place.]]
|[[File:Filter bed bio fail.PNG|300px|thumb|center|Erosion gullies and bare soil areas are present on the filter bed surface, indicating that concentrated flow occurs regularly into the BMP feature. (Photo Source: CVC).]]
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|'''[[Rainwater harvesting: Sizing and modeling#Cistern dimensions|Pump]]'''
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Pressurized device used to deliver stored rainwater to the hose bibs.
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*Inspect and test for proper function annually.
|[[File:Vegetation bio pass.PNG|315px|thumb|center|The planted portion of the bioretention cell is completely covered with dense, attractive vegetation which helps to maintain its stormwater treatment function and aesthetic value.]]
|[[File:Vegetation bio fail .PNG|290px|thumb|center|A larger portion of the bioretention cell has no vegetation cover which reduces its aesthetic value and could be negatively affecting its stormwater treatment function. Much less than 80% of the planting area is covered by living vegetation requiring immediate maintenance and reseeding.]]
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|'''Filter'''
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Cisterns may include an in-line filter device on the intake pipe or prior to delivery of rainwater to hose bibs.
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*Remove debris and sediment biannually to quarterly or as directed by the system manufacturer.
|[[File:Overflow bio pass.PNG|320px|thumb|center|The overflow outlet is free of damage and obstruction and functions as originally designed.]]
|[[File:Overflow bio fail.PNG|280px|thumb|center|The overflow outlet is partially obstructed with trash and debris which reduces its capacity to safely convey excess water from the BMP, likely due to excess ponding thus obstructing outflow and impairing overall drainage function of the BMP.]]
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|'''[[Overflow|Overflow Outlet]]'''
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Pipe connected to the cistern or [[rain barrels|rain barrel]] that conveys overflows to another drainage system (e.g., municipal storm sewer or other BMP).
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*Check for [[clogging|obstructions]] and remove any debris or sediment annually to biannually.
|[[File:MonitoringWell bio pass.PNG|340px|thumb|center|The well is undamaged and accessible and the cap is in place and secured to prevent unauthorized access.]]
|[[File:MonitoringWell bio fail.PNG|300px|thumb|center|The well standpipe has been damaged by snow plowing, which impairs its use for monitoring and is a safety hazard. With the cap unable to be secured unauthorized access can also occur.]]
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