Changes

# After every large storm event (e.g., 15 mm rainfall depth or greater) to ensure ESCs and pretreatment or flow diversion devices are functioning and adequately maintained.  View the table below, which describes critical points during the construction sequence when inspections should be performed prior to proceeding further. You can also download and print the table [https://wikidev.sustainabletechnologies.ca/images/a/a6/LID-IM-Guide-7.5-Underground-Infiltration-Systems.pdf '''here''']<br>

# After every large storm event (e.g., 15 mm rainfall depth or greater) to ensure ESCs and pretreatment or flow diversion devices are functioning and adequately maintained.  View the table below, which describes critical points during the construction sequence when inspections should be performed prior to proceeding further. You can also download and print the table [https://wikidev.sustainabletechnologies.ca/images/a/a6/LID-IM-Guide-7.5-Underground-Infiltration-Systems.pdf '''here''']<br>

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[[File:Catchbasin isnert underground.PNG|thumb|400px|A [[pretreatment]] device (catchbasin insert) upstream of an underground infiltration system inlet in need of cleaning out. These devices are designed to limit the amount of trash, debris, sediment, oil and grease entering the infiltration system, which helps to prevent clogging and maintain its drainage performance  (Source: TRCA, 2018<ref name="example1" />).]]  

[[File:Catchbasin isnert underground.PNG|thumb|400px|A [[pretreatment]] device (hydrodynamic (i.e., oil and grit) separator) upstream of an underground infiltration system inlet in need of cleaning out. These devices are designed to limit the amount of trash, debris, sediment, oil and grease entering the infiltration system, which helps to prevent clogging and maintain its drainage performance  (Source: TRCA, 2018<ref name="example1" />).]]  

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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.

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 [[permeable pavements]], organized by BMP component, along with recommended minimum frequencies. It also suggests higher frequencies for certain tasks that may be warranted for BMPs located in highly visible locations or those receiving flow from high traffic (vehicle or pedestrian) areas or those designed with higher than recommended impermeable drainage area to permeable BMP footprint area ratios ([[Notation|I:P ratios]]). Tasks involving removal of trash, debris and sediment and weeding/trimming of vegetation for BMPs in such contexts may need to be done more frequently (i.e., higher standards may be warranted).  

Periodic inspections done every 5 years (maintenance verifications) and every 15 years (performance verifications) post-construction over the operating life cycle of the BMP to ensure compliance with the maintenance agreement (e.g., [https://www.ontario.ca/page/environmental-compliance-approval Environmental Compliance Approval permit]) conditions, evaluate functional performance and determine when rehabilitation or replacement is necessary.

Individuals conducting [[vegetation]] maintenance and in particular, weeding (i.e., removal of undesirable vegetation), should be familiar with the species of [[Plant lists|plants]] specified in the planting plan and experienced in plant identification and methods of removing/controlling noxious weeds. Key resources on these topics are provided below at the links provided:

Requirements of the Ontario Occupational Health and Safety Act regulation for individuals working in confined spaces ([https://www.ontario.ca/laws/regulation/050632 O.Reg. 632/05]) must be adhered to during any inspection or

*[http://www.weedinfo.ca/en/ Agriculture and Agri-food Canada’s Weed Info database]

maintenance work on underground infiltration systems that involves entry into confined spaces (e.g., catchbasins, manholes, access hatches). Individuals working in such environments should be adequately trained on the use and maintenance of the necessary safety equipment and review hazards and safety plans regularly. Further information about Ontario’s Confined Spaces Regulation and Guideline can be accessed here: [https://www.ontario.ca/document/guideline-working-confined-spaces Confined Spaces Guideline - Ministry of Labour, Immigration, Training and Skills Development].

*[http://www.omafra.gov.on.ca/english/crops/facts/ontweeds/weedgal.htm Ontario Ministry of Agriculture, Food and Rural Affairs’ Ontario Weed Gallery]

 

*[http://www.omafra.gov.on.ca/english/crops/facts/noxious_weeds.htm Ontario Ministry of Agriculture, Food and Rural Affairs’ Noxious Weeds In Ontario list]

Table below describes routine maintenance tasks for underground infiltration systems ([[infiltration chambers]], [[infiltration trenches]], [[bioswales]], etc.) organized by BMP component, along with recommended minimum frequencies. It also suggests higher frequencies for certain tasks that may be warranted for BMPs located in highly visible locations or those receiving flow from high traffic (vehicle or pedestrian) areas. Tasks involving removal of trash, debris and sediment and weeding/trimming of vegetation for BMPs in such contexts may need to be done more frequently (i.e., higher standards may be warranted).  

*[https://www.ontarioinvasiveplants.ca/wp-content/uploads/2016/07/QRG_FINAL.pdf Ontario Invasive Plant Council’s Quick Reference Guide to Invasive Plant Species]

*[https://wrrc.arizona.edu/sites/wrrc.arizona.edu/files/OSU_Field%20Guide%20-%20Maintaining%20Rain%20Gardens%2C%20Swales%2C%20and%20Stormwater%20Planters.pdf Oregon State University Stormwater Solutions, 2013, Field Guide: Maintaining Rain Gardens, Swales and Stormwater Planters, Corvallis, OR.]

*[https://lonepinebooks.com/product/plants-of-southern-ontario-2/ Plants of Southern Ontario (book), 2014, by Richard Dickinson and France Royer, Lone Pine Publishing, 528 pgs.]

*[http://www.agrifs.ir/sites/default/files/Weeds%20of%20North%20America%20%7BRichard%20Dickinson%7D%20%5B9780226076447%5D%20%282014%29_2.pdf Weeds of North America (book), 2014, by Richard Dickinson and France Royer, University of Chicago Press, 656 pgs.]

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|+'''Permeable Pavements: Key Components, Descriptions and Routine I&M Requirements'''

|+'''Underground Infiltration Systems: Key Components, Descriptions and Routine I&M Requirements'''

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!style="width: 500px"|Comnponent

!style="width: 500px"|Component

!style="width: 1500px"|Description  

!style="width: 1500px"|Description  

!style="width: 1500px"|Inspection & Maintenance Tasks

!style="width: 1500px"|Inspection & Maintenance Tasks

!style="width: 550px"|<span style="color:red">('''Fail''')</span> Photo Example

!style="width: 550px"|<span style="color:red">('''Fail''')</span> Photo Example

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|'''[[Permeable pavements: Sizing|Contributing Drainage Area (CDA)]]'''

|'''[[Infiltration: Sizing and modeling|Contributing Drainage Area (CDA)]]'''

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Area(s) from which runoff directed to the BMP originates; includes the pavement itself and any adjacent impermeable pavement or roofs that drain to it.

Area(s) from which runoff directed to the BMP originates; includes both impervious (i.e., roofs and pavements) and pervious (i.e., landscaped) areas.

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*Remove trash, debris and sediment from pavements (biannually to quarterly) and eavestroughs (annually);

*Remove trash, debris and sediment from pavements (biannually to quarterly) and eavestroughs (annually);

*Replant or seed bare soil areas as needed.

*Replant or seed bare soil areas as needed.

|[[File:CDA Pass p.p.JPG|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:CDA pass underground.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:CDA Fail p.p.JPG|280px|thumb|center|Size of the CDA has changed from design assumptions (i.e. large asphalt area drains to a small portion of the permeable pavement). Evidence of surface ponding is visible.]]  

|[[File:CDA fail underground.PNG|280px|thumb|center|Point sources of contamination are present (i.e. accumulated sediment and debris from melted snow piles)]]  

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|'''[[Pretreatment]]'''

|'''[[Pretreatment]]'''

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Devices or features that retain trash, debris and sediment; help to extend the [[Cost analysis resources|operating life cycle]]; examples are eavestrough screens, [[Pretreatment|catch basin]] inserts and sumps, [[oil and grit separators]], [[inlets|geotextile-lined inlets]], [[Gravel diaphragms|gravel trenches]], [[Vegetated filter strips|grass filter strips]] and [[forebays]].

Devices or features that retain trash, debris and sediment, oil and grease; help to prevent obstructions and [[clogging]] of the infiltration area. Examples are eavestrough screens, [[Pretreatment|catch basin]] inserts (screens, baffles, filters) and sumps, [[oil and grit separators]], [[inlets|geotextile-lined inlets]], filters, isolator rows, and water quality [[forebay]] units.  

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*Remove trash, debris and sediment annually to biannually or when the device sump is half full;

*Remove trash, debris and sediment annually to biannually 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.

*Measure sediment depth or volume during each cleaning, or annually to estimate accumulation rate and optimize frequency of maintenance.

|[[File:Pretreat Pass p.p.JPG|280px|thumb|center|Although permeable pavers are generally considered [[pretreatment]] for other BMPs in a [[Low impact development treatment train tool|treatment train]] system, using eavestrough screens can act as pretreatment as they don't add to sediment build up and accumulation on the paver surface. (Photo Source: Guertin, 2010)<ref>Guertin, M. 2010. Simple Screen Gutter Guards Better Than Pro-Installed Systems (and way cheaper). Fine Homebuilding - The Daily Fix. Accessed July 17 2022. https://www.finehomebuilding.com/2010/08/17/simple-screen-gutter-guards-better-than-pro-installed-systems-and-way-cheaper</ref>]]  

|[[File:Pretreatment inlet pass underground.PNG|280px|thumb|center|[[Geotextile]]-lined stone inlet is free of sediment, trash and debris. Stones to slow down and spread out inflowing water remain in place.]]

|[[File:Pretreat Fail p.p.JPG|300px|thumb|center|Build up of leads, sediment and leaf detritus in an eavestrough downspout disconnection leading to a permeable pavement surface. If not cleaned regularly this can lead to clogged pores between the pavers reducing the infiltration rate where the downspout deposits water onto the feature. (Photo Source: My Gutter Pro, 2021)<ref>My Gutter Pro. 2021. Clogged Downspout : Causes and Solutions. 10 April 2021. Accessed July 19 2022. https://mygutterpro.com/downspout-clog/</ref>]]  

|[[File:Pretreatment inlet Fail underground.PNG|300px|thumb|center|Accumulated sediment, trash and debris in the hydrodynamic (i.e., oil and grit) separator is occupying greater than 50% of its storage capacity. (Photo Source: SWC Canada, 2020)<ref>Storm Water Compliance (SWC) Canada Inc. 2020. OIL GRIT SEPARATORS/WATER QUALITY STRUCTURES. Accessed 02 August 2022. https://www.swccanada.com/system-types/oil-grit-separators</ref>]]  

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|'''[[Inlets]]'''

|'''[[Inlets]]'''

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Structures that deliver water to the BMP (e.g., impermeable pavement edges, [[pipes]] from roof downspouts or catchbasins).

Structures that deliver water to the BMP such as curb-cuts and geotextile-lined inlets or pipes connected to catchbasins, hydrodynamic (oil and grit) separators (HDS), filters, manholes, sub-drains of other features or roof downspouts.

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*Keep free of obstructions;

*Keep free of obstructions;

*Remove trash, debris and sediment biannually to quarterly;

*Remove trash, sediment and debris biannually (spring and late fall) to quarterly (spring, summer, early fall, late fall/early winter);

*Make note of sediment depth or volume during each cleaning or annually to estimate accumulation rate and optimize frequency of maintenance

*Make note of sediment depth or volume during each cleaning or annually to estimate accumulation rate and optimize frequency of maintenance.

|[[File:Inlet Pass p.p.JPG|285px|thumb|center|Impermeable pavement edges along the edge of the pervious concrete and impermeable asphalt graded so excess sheet flow is infiltrated down through the pores of the infiltration BMP. (Photo Source: Fairfax County, 2014)<ref>Fairfax County. 2014. Protecting our Environment, one Stormwater Practice at a Time - Permeable Pavements. April 2014. Accessed: July 20 2022. https://www.fairfaxcounty.gov/publicworks/sites/publicworks/files/assets/documents/pdf/factsheets/permeable-pavement.pdf</ref>]]  

|[[File:Inlets pass underground.PNG|285px|thumb|center|There are no obstructions at the inlet and stormwater can freely flow into the BMP.]]  

|[[File:Curb inlet grade.jpg|300px|thumb|center|Accumulated sediment, poor grading and vegetation is preventing stormwater from entering the [[swale]]. Sediment on the curb cut surface behind of the inlet indicates ponding is also occurring and is depositing water towards the permeable paver surface.]]  

|[[File:Inlets fail underground.PNG|300px|thumb|center|Sediment has accumulated in the inlet pipe to the infiltration trench and is fully obstructing flow of stormwater into the BMP.]]  

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|'''[[Permeable pavements: Specifications|Pavement Surface]]'''

|'''[[Overflow|Overflow Outlet]]'''

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The surface of the pavement, including pavers/pavement, joints and edge restraints (e.g., curbs, edging); should not allow water to pond on the surface so any observation or evidence of surface ponding (e.g., sediment caking on the pavement) indicates a drainage problem.

Structures (e.g., sub-drain/[[underdrain]] pipe connected to a manhole, conventional storm sewer pipe, or control manhole with weir wall) that convey flow exceeding the storage capacity to another drainage system or BMP.  

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*Check for sediment, surface ponding, deformation, sink holes, damage and loss of joint fill;

*Keep free of obstructions;

*Remove trash regularly (biannually-quarterly);

*Remove trash, sediment, debris, oil and grease biannually (spring and late fall) to quarterly (spring, summer, early fall, late fall/early winter).

|[[File:Outlet & overflow pass underground.PNG|320px|thumb|center|The overflow outlet weir wall and storm sewer pipe in the control manhole of this infiltration chamber system is free of damage and obstruction and functions as designed to safely convey excess water from the BMP.]]  

*Sweep and vacuum interlocking and rigid pavements regularly (annually-biannually) with regenerative air/pure vacuum sweeper;

|[[File:Overflow Fail p.p.JPG|280px|thumb|center|Sediment and debris has accumulated in the overflow outlet pipe which impairs its function to convey excess water from the BMP.]]  

*Plow snow as needed and spread deicers sparingly during winter;

*Repair ruts or local sinking of 15 mm or greater over a 3 metre length, adjacent pavers or cracks in pervious concrete or porous asphalt are vertically offset by 5 mm or greater and paver joint fill is missing or below 15 mm from the paver surface.

|[[File:Pavesurface Pass p.p.JPG|350px|thumb|center|No damage, displacement or sinking of the permeable surface is visible and there are no weeds growing between paver joints.]]  

|[[File:Pavesurface Fail p.p.JPG|280px|thumb|center|The pavement surface has sunk in local areas, creating a trip hazard and the potential for further damage from snow plowing and parked vehicles nearby.]]

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|'''[[Vegetation]]'''

|'''[[Underdrain|Sub-drain]]'''

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Applies to grid paver systems only; a mixture of deep rooting perennial grasses or low growing ground covers, tolerant to both wet and dry conditions and salt (if receiving impermeable pavement runoff); roots uptake water and return it to the atmosphere, provide habitat for soil organisms that break down pollutants trapped in the soil and help maintain soil structure and permeability.

Comprised of perforated pipe(s) surrounded by gravel and may be wrapped in geotextile filter fabric; installed in the gravel water storage layer or chamber unit openings to collect and convey treated water to an adjacent drainage system or other BMP; may also include a flow restrictor.

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*Grid systems with soil and grass fill are maintained like lawns;

*Keep perforated pipes and flow restrictors free of obstructions;

*In the first 2 months water frequently (biweekly in the absence or rain) and as needed (e.g., bimonthly) over the remainder of the first growing season;

*Inspect flow restrictor and flush with a garden hose or pressure washer regularly (biannually to quarterly).

*Remove weeds and undesirable plants biannually to quarterly;

|[[File:Underdrain pass underground.PNG|310px|thumb|center|The sub-drain outlet pipe from the infiltration chamber system is not obstructed by sediment, debris or roots and shows no signs of damage.]]  

|[[File:Underdrain fail underground.PNG|300px|thumb|center|A perforated pipe in an exfiltration storm sewer system is clogged by sediment and debris which inhibits its drainage function.]]  

*Do not apply chemical fertilizers.

|[[File:Veg Pass p.p.JPG|315px|thumb|center|The vegetation cover on the permeable pavement is turf grass as specified in the final design and contains very few weeds. (Photo source: WEF).]]  

|[[File:Veg Fail p.p.JPG|290px|thumb|center|The turf grass cover on the permeable walkway is not thriving in some areas and needs cutting in others. It is also impairing the aesthetic value of the BMP.]]  

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|'''[[Overflow|Overflow Outlet]]'''

|'''[[Monitoring well]]'''

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Structures (e.g., catchbasin, curb-cut, [[swale]]) that convey flow that exceeds the storage capacity of the BMP to another drainage system (e.g., municipal storm sewer or other BMP).  

[[Wells|Perforated standpipe]] that extends from the bottom of the excavation to just below the pavement surface and contains perforations or slots to allow [[Digital technologies|measurement of subsurface water level]]; used to track drainage performance over the operating life cycle of the BMP.

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*Keep free of obstructions;

*[[Wells|Standpipes]] should be securely capped on both ends and protected from damage by vehicular traffic or foot traffic by a lockable casing.

*Remove trash, debris and sediment biannually to quarterly.

|[[File:Monitoring well pass underground.PNG|340px|thumb|center|The well is undamaged and accessible and the cap is in place and secured to prevent unauthorized access]]

|[[File:Overflow Pass p.p.JPG|320px|thumb|center|The overflow outlet is free of damage and obstruction and functions as designed to safely convey excess water from the BMP.]]  

|[[File:Monitoring well fail underground.PNG|300px|thumb|center|The well was buried during landscaping and found covered only by filter cloth (i.e. cap missing).]]

|[[File:Overflow Fail p.p.JPG|280px|thumb|center|The overflow outlet is obstructed with sediment which impairs its function to convey excess water from the BMP.]]  

 

*Prohibit stockpiling of [[Soil groups|soil]], [[sand]], [[compost]] or unwashed [[gravel]] within the [[Infiltration: Sizing and modeling|CDA]] and [[inlets]] to prevent [[clogging]] with sediment.

*For BMPs with [[underdrains|sub-drains/underdrains]] and flow restrictors, [[Pretreatment|pretreatment devices]] that prevent floating trash and debris from entering the practice should be used to prevent obstruction of the sub-drain pipe/flow restrictor.

*For BMPs equipped with [[pretreatment]] that detains floating contaminants (e.g., oil and grease, trash and debris), such as [[oil and grit separators|hydrodynamic separators/oil and grit separators]] or [[forebays]] with baffle walls, remove trash and debris first using a bucket strainer. Floating oils and grease should then be removed off the top of the water using a vacuum truck.

*Provide a means of draining [[infiltration chambers]] by gravity (e.g., pipe and valve through the control structure weir wall) to make [[inspection and maintenance]] work that requires drainage of the BMP (e.g., filter bed and control structure inspection and sediment removal, repairs to control structure) easier to perform.

*To remove accumulated sediment from [[underdrain]] pipes and chamber system units, a hydrovac truck equipped with a JetVac nozzle should be employed that uses pressured jets of water to propel itself through the structure while scouring and directing suspending sediments to a collection point. As the nozzle is retrieved, the sediment is flushed into the manhole or catchbasin sump for removal by vacuuming. Selecting an appropriate JetVac nozzle will depend on the structure being cleaned. For chamber system units, fixed nozzles designed for culverts or large diameter pipe cleaning with rear-facing jets are preferable (consult product manufacturer for further guidance).

 

 

 

[[File:Underdrain clogded underground.PNG|thumb|340px|The manhole sump is becoming filled with sediment, trash and excess and debris, which is beginning to impair flow of stormwater into the [[perforated pipe]] of the [[exfiltration trench|exfiltration storm sewer system.]]]]

 

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|'''[[Underdrain|Sub-drain]]'''

| rowspan="2"|'''[[Underdrains|Sub-drain/Underdrain]]'''

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Optional component; [[Pipes|perforated pipe(s)]] surrounded by [[gravel]] and may be wrapped in [[Geotextile|geotextile filter fabric]]; installed in the base or sub-base gravel layer to collect and convey treated water to an adjacent drainage system or other BMP; may also include a flow restrictor.

*Schedule hydro-vac truck or drain-snaking service to remove the obstruction.

|Perforated pipe caps are missing or damaged

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*Keep pipe and flow restrictor free of obstructions by flushing annually;

*Replace missing or damaged caps.

|[[File:Underdrain Pass p.p.JPG|310px|thumb|center|The solid section of the sub-drain pipe is not obstructed by sediment, debris or roots and shows no signs of damage.]]

|[[File:Underdrain Fail p.p.JPG|300px|thumb|center|A section of the sub-drain pipe has been crushed which substantially reduces its conveyance capacity]]

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|'''[[Monitoring well]]'''

|'''[[Forebays|Isolator Row or Water Quality Forebay Unit]]'''

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[[Wells|Perforated standpipe]] that extends from the bottom of the excavation to just below the pavement surface and contains perforations or slots to allow [[Digital technologies|measurement of subsurface water level]]; used to track drainage performance over the operating life cycle of the BMP.

Sump is ≥ half full or average sediment depth is ≥ 8 cm

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*[[Wells|Standpipes]] should be securely capped on both ends and protected from damage by vehicular traffic by a casing.

*Schedule maintenance work; First remove floating trash and debris by bucket strainer, then oil and grease by petroleum absorbing sponge. Then fully drain the row or unit by gravity, pumping or vacuuming, and remove accumulated sediment through use of a hydro-vac truck equipped with JetVac nozzle.

|[[File:Monitor Fail p.p.JPG|300px|thumb|center|The well cap is missing and the casing is clogged by sediment, preventing access for monitoring and allowing sediment to flow into the sub-drain system.]]

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|'''[[Flow through riser|Control Structure]]'''

|'''Manhole control structure'''

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Manhole or catchbasin to which the subdrain outlets that provides access to the [[underdrain]] and flow restrictor. Inspect for accessibility, damage and sediment.

Structure or pipe connection is leaking and impairing the water storage capacity or function of the BMP

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*Remove trash, debris and sediment regularly (biannually/quarterly)..

*Schedule work to repair cracks or seal leaking components. The BMP may need to be fully drained to make such repairs.  

|[[File:Control Struct Pass p.p.JPG|340px|thumb|center|TThere is some sediment accumulated in the manhole but it is not impairing the flow of stormwater into or out of the BMP. (Photo source: SWC Canada)]]

|[[File:Control Struct Fail p.p.JPG|300px|thumb|center|The manhole sump is full of sediment and debris and it is beginning to impair flow of stormwater into a perforated pipe of the exfiltration storm sewer system.]]

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