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Key Design and Plan Review Considerations (view source)
Revision as of 21:28, 28 September 2022
, 2 years agoCreated page with "File:The key elements of LID.gif|thumb|600px|A graphic showing the key benefits for effective LID BMP implementation. These elements along with others should be considered d..."
[[File:The key elements of LID.gif|thumb|600px|A graphic showing the key benefits for effective LID BMP implementation. These elements along with others should be considered during the planning and design phases of LID implementation (Source: Wikimedia Commons, 2012<ref>Wikimedia Commons. 2012. File:The key elements of LID.gif. http://zoe-s-wiki.wikispaces.com/Low+Impact+Development. https://commons.wikimedia.org/wiki/File:The_key_elements_of_LID.gif</ref>).]]
{{TOClimit|2}}
==Overview==
Designing LID BMPs with ease of inspection and maintenance in mind is critical to the affordability of municipal stormwater infrastructure asset management programs and must be considered early on in the overall activity. Generally this occurs during the design and an early stage in the plan review and approval process. The following sections provide tips on tailoring the design of LID BMPs to help reduce the frequency of structural repairs and make inspection and maintenance tasks easier and cheaper to perform by either municipal staff or hired external consultants.
==Provide Runoff Pretreatment==
[[Pretreatment]] refers to techniques or devices used to retain coarse materials suspended in stormwater runoff, either through filtration or settling, before it enters the BMP rendering it inefficient over time. Proper pretreatment extends the operating phase of the BMP’s life cycle by reducing the rate of accumulation of coarse sediment, thus delaying the need for at times expensive structural repairs like unclogging filter beds, pipes and orifices. Common pretreatment devices include [[vegetated filter strips]], [[Enhanced swales|grass swales]], [[geotextile]]-lined inlet filters/liners, [[check dams]], [[forebays]], eavestrough screens or filters, [[Oil and grit separators| oil and grit separators]] (i.e., hydrodynamic separators) and catch basins or manholes containing baffles, filters and sumps. One important consideration for pretreatment is that these devices require frequent (e.g., annual) sediment and trash removal maintenance and should be easy to access by personnel, vehicles and equipment needed to perform inspection and maintenance tasks.
[[File:Oil-grit separator USGS 2002.png|thumb|350px|Example oil-grit separator USGS 2002 (Wikimedia commons)]]
==Design Low Maintenance Conveyance Systems==
The design of conveyance systems that carry stormwater into the BMP should anticipate potential maintenance issues and include features to minimize or avoid them.
For example, during large storm events, rapidly flowing water into or out of the BMP often causes [[erosion]] in vegetated practices. Inlet and outlet designs should consider protective features that prevent erosion. The size of inlets to BMPs and their slope also needs careful consideration as small, gently sloping openings are easily clogged with coarse debris and sediment which could cause stormwater flows to by-pass or not enter the BMP, increasing maintenance needs.
*[[Curb cuts]] should curve into the BMP so that flowing stormwater does not have to turn sharply to enter and inlets should be sloped at between 5 and 10%.
*[[Inlets]] should also be easily accessible and unobstructed by permanent covers to make trash, sediment and debris removal maintenance easy to perform.
*When designing stormwater infiltration BMPs, consideration should be given to where the majority of trash, sediment and debris will accumulate in the BMP and where snow storage will occur (a significant source area for sediment and debris).
*Infiltration BMPs should include [[pretreatment]] devices, inlet designs or forebays that allow accumulation to occur without blocking inflow (e.g., 5 cm change in grade between pavement surface and BMP surface) and that isolate sedimentation areas from the main portions of the filter bed so that the area disturbed through routine sediment removal maintenance is minimized.
==Inspection & Maintenance Features==
During planning and design phases of an LID management plan, consideration for how they will be maintained (what equipment is needed, who is responsible for conducting maintenance, how often should said maintenance occur for a given LID BMP? etc.) and what features are needed to perform necessary inspection and maintenance tasks are all required questions to be answered by the municipality.
The following table provides some examples of inspection and maintenance features that should be considered in the BMP process:
{| class="wikitable" style="width: 1275px;"
|+'''I&M Features to be Considered in BMP Design Phase'''
|-
!<br>'''LID BMP Type'''
!<br>'''Description'''
|-
|rowspan="3"|'''Infiltration BMPs'''
|-
|For infiltration BMPs, [[Wells|monitoring wells]] that extend to the bottom and standpipes or manholes connected to [[underdrains|sub-drains]] that allow access for drainage performance verification through water level measurements and routine flushing of sediment from pipes.
|-
|For infiltration BMPs, [[underdrains|sub-drain pipes]] should be 200 mm in diameter and be connected to manholes, maintenance hatches or standpipes (for standpipes, it is best to use two (2) 45 degree couplings) to allow for inspection by closed circuit camera (i.e., push camera) and sediment removal by jet-vac equipment.
|-
|rowspan="3"|'''Vegetated BMPs'''
|-
|For vegetated BMPs, consideration should be given to what source of water will be drawn upon for irrigation during the establishment/warranty period, how it will be delivered to the BMP (e.g., is equipment with sufficient volume and pressure available?), and in some cases an irrigation system should be part of the BMP design (e.g., [[green roofs]]).
|-
|For vegetated BMPs in high pedestrian traffic areas, consider the need for walkways or stepping stones and barriers to help limit foot traffic to designated portions of the BMP, or discourage it altogether if it is causing [[vegetation]] [[Maintenance, Rehabilitation and Repair|maintenance issues]].
|-
|rowspan="2"|'''Underground Pretreatment or BMPs'''
|-
|For underground pretreatment devices or BMPs, the associated manholes or maintenance hatches should be close to a drivable surface/path that can support the heavy vehicles needed for sediment removal maintenance (e.g., hydrovac trucks) and consider installing a staff gauge or graduated measuring tape to allow sediment depth to be assessed visually from the ground surface, without having to enter the confined space.
|-
|rowspan="3"|'''[[Green Roofs]] and [[Blue roofs|Blue Roofs]]'''
|-
|Safe and efficient means of accessing and exiting a [[green roof]] or [[Blue roofs|blue roof]] site for installation, inspection and maintenance is a primary consideration as it will influence the time and effort required to transport tools, equipment and materials to and from the site.
|-
|For [[green roofs]] and [[Blue roofs|blue roofs]], tie-off points for ladders and personal fall protection safety equipment should be incorporated in the roof design for use by individuals performing inspection and maintenance work.
|-
|rowspan="4"|'''General Considerations'''
|-
|Lockable caps on [[wells|monitoring wells]] and sub-drain clean-out standpipes to prevent unauthorized access, tampering, or vandalism.
|-
|Features for taking the BMP off-line or draining stored water by gravity to improve ease of inspection and sediment removal maintenance tasks.
|-
|[[Inlets]] should be readily accessible from surface conveyances, catchbasins, manholes or access hatches to avoid the need for specialized equipment for inspection (e.g., closed circuit or remote controlled cameras).
|-
|}
==Inclusion of Planting Plans==
[[File:Kortright Planting Plan.PNG|700px|thumb|An example of a [https://wikidev.sustainabletechnologies.ca/images/a/ac/Bio-Retention_Cell-Cell_A_planting_plan_20130415.pdf TRCA project Planting Plan] for a [[Bioretention]]/[[Bioswale]] BMP located at the Kortright Centre, in Vaughan, ON. listed with appropriate [[plants]], [[grasses]], [[trees]] and [[shrubs]] species for the area with their scientific and common names listed along with the quantity to be planted, plant type, site and condition characteristics, flowering assemblages and colours and mature height (Source: TRCA, 2013.)|link=https://wikidev.sustainabletechnologies.ca/images/a/ac/Bio-Retention_Cell-Cell_A_planting_plan_20130415.pdf]]
All vegetated BMP designs should include planting plans that specify [[Plant selection|species]] that can tolerate both wet and dry conditions and, for BMPs that will receive de-icing salt laden runoff during winter, species
that are salt tolerant. Further consideration should be given to species that are both pollution and soil compaction tolerant given the location of many BMPs along roadways and near public spaces. Where possible, planting should done during the wettest seasons/months of the year (e.g., early spring and mid-to-late fall) to help minimize the need for irrigation (and staff time and equipment) during the establishment/warranty period. Use of drought-tolerant and native species will help minimize or eliminate the need for irrigation during the operating phase of the BMP life cycle. Good vegetation cover on the surface and side slopes of BMPs helps to maintain infiltration function, contributes to runoff volume reduction function through evapotranspiration, and helps prevent erosion of soil and/or mulch cover from flowing overland water.
Both common and botanical (i.e., species Latin name) names should be used on [[Planting design#Planting plans and specifications|planting plans]] so that inspectors and maintainers of the vegetation are better able to recognize or develop the means of recognizing the plants in the field and distinguishing them from pervasive weeds. Planting plans should also specify the planting method (e.g., seed vs. sod) and plant or container size (e.g., saplings vs. caliper tree; plugs vs. pots; bare root vs. root ball). Any deviations from the planting plan or species substitutions should be noted on as-built drawings/planting plans.
All construction contracts that include [[vegetation]] should specify a minimum two (2) year warranty period (i.e., establishment period) for the plants, which begins after planting is completed, and ends when the BMP is assumed by the owner. Over the warranty/establishment period the contractor is responsible for routine maintenance tasks (e.g., watering, weeding, and sediment and trash removal).
Consideration should be given to specifying a phased approach to planting in construction contracts, in which planting occurs in two stages (e.g., fall and the following spring; spring and the following fall) to help ensure the full palette of plants specified in the plan are available. Thereby, any failed plantings from the first stage of planting are sure to be replaced in the second. If many or all plantings of a certain species do not survive the first phase, they can be substituted with another more tolerant or suitable species in the second (A list of suitable shrubs, trees, graminoids, etc. can be found on our [[Plant lists]] page).
==Inclusion of Sediment Removal Plans==
As mentioned previously, it is recommended that, where possible, [[pretreatment]] devices be included in BMP designs that help retain coarse sediment and debris in an easily accessible location before it enters the BMP itself. However even with pretreatment devices in place, fine sediment will inevitably reach the BMP and accumulate over time. LID BMP designs need to consider how sediment can be removed from associated manhole sumps, pretreatment devices, inlets and pipes, and include adequate features and routes for access by necessary equipment.
<br>
[[File:MaintenancePICP.png|thumb|450px|Vehicle used for vacuum maintenance of [[permeable pavements]] (Source: STEP).]]
{|class="wikitable" style="width:750px;"
|+'''Sediment Removal Equipment per BMP Type'''
|-
!<br>'''LID BMP Type'''
!<br>'''Equipment Required for Sediment Removal'''
|-
|'''[[Permeable pavement|Permeable Pavers]]'''
|For permeable pavements, regenerative air sweeper (for routine maintenance) or vacuum sweeper (for rehabilitation) equipment (e.g., street cleaner trucks or more compact units) will be needed, so designs should allow access to the majority of the surface by necessary equipment (e.g., minimize obstructions and sharp corners);
|-
|'''[[Inlets]], [[Vegetated filter strips|Grass filter strips]], [[gravel diaphragms]], [[Check dams]], and [[Forebays]]'''
|Use of a vacuum sweeper truck with hose attachment, soil blower truck (operated in reverse), sidewalk vacuum or hand tools (e.g., rakes and shovels) are options for each of these [[Pretreatment|pretreatment devices]] and flow controlling/detention devices.
|-
|'''Vegetated BMPs'''
|For removing sediment from the filter beds of vegetated BMPs, use of a vacuum truck with hose attachment, soil blower truck (operated in reverse) or hand tools are options that can minimize the need to remove established [[vegetation]], while use of a small excavator or backhoe can also be effective, but will require vegetation removal and transplanting (where feasible) or replacement after the work is completed.
|-
|'''Underground BMPs'''
|For underground BMPs (e.g., [[Infiltration chambers|underground infiltration systems]], [[soil cells]]) and associated [[pretreatment]] devices (e.g., manhole sumps, [[Oil and grit separators|hydrodynamic/oil and grit separators]], isolator rows, [[forebays]]), and in-line filters, hydro-vac trucks will likely be needed.
|-
|}
<br>
For underground conveyances (i.e., catchbasins, manholes, [[pipes]]), BMPs, [[pretreatment]] devices, and in-line [[Media filters|filters]], sediment removal often requires crews performing the work to enter confined spaces. Contractors or staff performing the work must have confined space entry training to satisfy occupational health and safety requirements ([https://www.ontario.ca/laws/regulation/050632#:~:text=(1)%20Every%20worker%20who%20enters,632%2F05%2C%20s. Ont. Reg. 632/05 – Confined Spaces Regulation]). <br>
How the material removed from conveyances, LID BMPs, [[pretreatment]] devices and in-line filters will be safely and sustainably managed also needs consideration. Due to the small drainage area of most LID BMPs, the rate at which they accumulate sediment and associated contaminants tends to be low in comparison to centralized stormwater treatment facilities like [[SWM ponds|stormwater ponds]] or detention chambers/tanks that receive drainage from much larger areas. As a result, the potential for sediment accumulated in LID BMPs to qualify as contaminated according to [https://www.ontario.ca/page/soil-ground-water-and-sediment-standards-use-under-part-xv1-environmental-protection-act Ontario Brownfields Regulation 153/04 standards for soil and sediment (Ministry of the Environment, 2011)<ref>Ministry of the Environment. 2011. Soil, ground water and sediment standards for use under Part XV.1 of the Environmental Protection Act. This document provides Ontario’s soil, ground water and sediment standards effective July 1, 2011. PIBS # 7382e01. https://www.ontario.ca/page/soil-ground-water-and-sediment-standards-use-under-part-xv1-environmental-protection-act</ref>] is low. <br>
Most often, contractors or staff performing sediment removal maintenance procedures will be cleaning multiple BMPs and pretreatment devices at multiple sites on any given day. At the end of the day, the mixture of material collected either manually, or by vacuum equipment (e.g., regenerative air or vacuum sweeper, vacuum/soil blower truck, hydro-vac truck) will include a mixture of re-usable, recyclable and non-recyclable constituents. In order to recover reusable and recyclable materials and minimize the volume of material needing to be managed otherwise, the mixture should be screened to isolate trash (for recycling or disposal), natural debris and [[mulch]] (for composting), and [[gravel]] - to pebble-sized [[aggregates]] (for washing and re-use) from finer (i.e., [[sand]] - to [[Texture|clay-sized]]) material. The sand- to clay-sized material (i.e., material passing a 2 mm diameter ([https://www.endecotts.com/faq/sieves-and-calibration/american-standard-test-sieve-series-astm/ ASTM No. 10]) sieve) should then be assessed and managed in accordance with [https://www.ontario.ca/laws/regulation/900347 provincial regulations (O.Reg. 347)].
[[File:Key Design and Plan Review Considerations Schematic.png|thumb|600px|Recommended process for determining reuse and disposal options for sediment from stormwater management BMPs. [https://sustainabletechnologies.ca/app/uploads/2018/04/SWMFG2016_Guide_April-2018.pdf Source: Inspection and Maintenance Guide for Stormwater Management Ponds and Constructed Wetlands (TRCA and CH2M, 2016)]<ref name="example1">Citation: Toronto and Region Conservation Authority (TRCA) and CH2M Canada. 2016. Inspection and Maintenance Guide for Stormwater Management Ponds and Constructed Wetlands. Toronto and Region Conservation Authority, Vaughan, Ontario. https://sustainabletechnologies.ca/app/uploads/2018/04/SWMFG2016_Guide_April-2018.pdf</ref>. <br>
<small>'''Note:''' This flow chart does not depict MECO policy but rather a recommended approach based on TRCA’s understanding of current MECP operational practices.</small>]]
Laboratory testing to determine if beneficial reuse (e.g., spreading on landscaped areas or blending with other constituents for use as a soil conditioner) of the remaining sand- to clay-sized constituents is an option that should be considered. Determining beneficial reuse options for all constituents of the accumulated material could provide substantial savings in terms of costs associated with transporting and managing the material off-site. For more detailed guidance on what types of testing should be done on sediment accumulated in SWM BMPs and what standards to apply to determine when beneficial re-use is an option, refer to [https://sustainabletechnologies.ca/app/uploads/2018/04/SWMFG2016_Guide_April-2018.pdf Chapter 9 of the Inspection and Maintenance Guide for Stormwater Management Ponds and Constructed Wetlands] (TRCA and CH2M, 2016)<ref name="example1" />. The following flow chart (to the right of the page) provides an overview of the process recommended in the aforementioned guide for determining sediment reuse and disposal options.
===Recommended Lab Testing for Sediment Quality===
The selection of sediment quality analysis parameters should reflect the Contributing Drainage Area's (CDA) land use characteristics and reported spill history. The following are the suggested minimum lists of analytes that would be suitable for sites with no history of point source contamination. It is recommended that the [https://www.ontario.ca/page/report-pollution-and-spills MECP be contacted to determine if any spill events] or other site specific circumstances would require additional analytes as well. The following step-by-step process would provide the data needed to evaluate the feasibility of beneficial use of the sediment or landfill disposal options.
====1. Leachate Test====
As required by [https://www.ontario.ca/laws/regulation/900347 O.Reg. 347], testing of leachate toxicity by the Toxicity Characteristic Leaching Procedure (TCLP), establishes whether or not the sediment is hazardous waste, which would then require proper disposal at a hazardous waste facility. The TCLP uses an acetic acid solution designed to simulate a possible worst-case leaching conditions scenario that could occur on a given study site that contains contaminated soils, or any other organic matter that will degrade over time (putrefaction) (Intrakamhaeng, et al. 2019<ref>Intrakamhaeng, V., Clavier, K.A., Roessler, J. G., and Townsend, T. G. 2019. Limitations of the toxicity characteristic leaching procedure for providing a conservative estimate of landfilled municipal solid waste incineration ash leaching, Journal of the Air & Waste Management Association, 69:5, 623-632, DOI: 10.1080/10962247.2019.1569172</ref>. This information is typically required by the MECP as a key first step in characterizing sediment. It may be advisable to conduct this analysis concurrently with Step 2 ([https://www.ontario.ca/laws/regulation/040153 O.Reg. 153/04 Bulk Soil Analysis]) so that samples for both tests can be collected during the same visit.
====2. O.Reg. 153/04 Bulk Soil Analysis====
Bulk soil analysis based on the [https://www.ontario.ca/laws/regulation/040153 O.Reg. 153/04 Standard] is carried out to evaluate whether sediment is suitable for beneficial use or requires landfill disposal. The OMOECC has, on a case-by-case basis, accepted the contaminant thresholds in O.Reg. 153/04 Table 1 as a basis for classifying sediment as
inert. Inert sediment can be used off-site without regulatory approval. Sediments that exceed Table 1 soil standards would require a risk evaluation to identify potential beneficial use options according to the figure to the right. <br>
The following is a base list of bulk soil analytes to be tested. It may be necessary to include additional analytes if land use activities in the CDA or past spills are believed to have introduced contaminants that are listed in the Standards but not included in this list.
*Trace metal scan including hot water extractable boron
*Cyanide
*Polycyclic Aromatic Hydrocarbons (PAHs)
*Petroleum Hydrocarbons (PHCs)
*Sodium Adsorption Ratio (SAR)
*Electrical Conductivity (EC)
*Particle Size Distribution (PSD)
====3. Topsoil Analysis and Certified Crop Advisor Report for Beneficial Use Evaluations====
The topsoil analysis would only be conducted if the O.Reg. 153/04 bulk soil tests determine that the sediment does not require landfill disposal due to high contamination levels. Topsoil analysis would be necessary to demonstrate that amending the receiving site soils with the sediment would provide a benefit to the soils, as required by the [https://www.ontario.ca/laws/statute/02n04 Nutrient Management Act], without inhibiting plant growth.
The list of analytes to be considered includes:
*Trace metal scan including hot water extractable boron
*SAR
*EC
*pH
*Soil Organic Matter (OM)
*Extractable (i.e., Available) Nutrients
*PSD
==References==
{{TOClimit|2}}
==Overview==
Designing LID BMPs with ease of inspection and maintenance in mind is critical to the affordability of municipal stormwater infrastructure asset management programs and must be considered early on in the overall activity. Generally this occurs during the design and an early stage in the plan review and approval process. The following sections provide tips on tailoring the design of LID BMPs to help reduce the frequency of structural repairs and make inspection and maintenance tasks easier and cheaper to perform by either municipal staff or hired external consultants.
==Provide Runoff Pretreatment==
[[Pretreatment]] refers to techniques or devices used to retain coarse materials suspended in stormwater runoff, either through filtration or settling, before it enters the BMP rendering it inefficient over time. Proper pretreatment extends the operating phase of the BMP’s life cycle by reducing the rate of accumulation of coarse sediment, thus delaying the need for at times expensive structural repairs like unclogging filter beds, pipes and orifices. Common pretreatment devices include [[vegetated filter strips]], [[Enhanced swales|grass swales]], [[geotextile]]-lined inlet filters/liners, [[check dams]], [[forebays]], eavestrough screens or filters, [[Oil and grit separators| oil and grit separators]] (i.e., hydrodynamic separators) and catch basins or manholes containing baffles, filters and sumps. One important consideration for pretreatment is that these devices require frequent (e.g., annual) sediment and trash removal maintenance and should be easy to access by personnel, vehicles and equipment needed to perform inspection and maintenance tasks.
[[File:Oil-grit separator USGS 2002.png|thumb|350px|Example oil-grit separator USGS 2002 (Wikimedia commons)]]
==Design Low Maintenance Conveyance Systems==
The design of conveyance systems that carry stormwater into the BMP should anticipate potential maintenance issues and include features to minimize or avoid them.
For example, during large storm events, rapidly flowing water into or out of the BMP often causes [[erosion]] in vegetated practices. Inlet and outlet designs should consider protective features that prevent erosion. The size of inlets to BMPs and their slope also needs careful consideration as small, gently sloping openings are easily clogged with coarse debris and sediment which could cause stormwater flows to by-pass or not enter the BMP, increasing maintenance needs.
*[[Curb cuts]] should curve into the BMP so that flowing stormwater does not have to turn sharply to enter and inlets should be sloped at between 5 and 10%.
*[[Inlets]] should also be easily accessible and unobstructed by permanent covers to make trash, sediment and debris removal maintenance easy to perform.
*When designing stormwater infiltration BMPs, consideration should be given to where the majority of trash, sediment and debris will accumulate in the BMP and where snow storage will occur (a significant source area for sediment and debris).
*Infiltration BMPs should include [[pretreatment]] devices, inlet designs or forebays that allow accumulation to occur without blocking inflow (e.g., 5 cm change in grade between pavement surface and BMP surface) and that isolate sedimentation areas from the main portions of the filter bed so that the area disturbed through routine sediment removal maintenance is minimized.
==Inspection & Maintenance Features==
During planning and design phases of an LID management plan, consideration for how they will be maintained (what equipment is needed, who is responsible for conducting maintenance, how often should said maintenance occur for a given LID BMP? etc.) and what features are needed to perform necessary inspection and maintenance tasks are all required questions to be answered by the municipality.
The following table provides some examples of inspection and maintenance features that should be considered in the BMP process:
{| class="wikitable" style="width: 1275px;"
|+'''I&M Features to be Considered in BMP Design Phase'''
|-
!<br>'''LID BMP Type'''
!<br>'''Description'''
|-
|rowspan="3"|'''Infiltration BMPs'''
|-
|For infiltration BMPs, [[Wells|monitoring wells]] that extend to the bottom and standpipes or manholes connected to [[underdrains|sub-drains]] that allow access for drainage performance verification through water level measurements and routine flushing of sediment from pipes.
|-
|For infiltration BMPs, [[underdrains|sub-drain pipes]] should be 200 mm in diameter and be connected to manholes, maintenance hatches or standpipes (for standpipes, it is best to use two (2) 45 degree couplings) to allow for inspection by closed circuit camera (i.e., push camera) and sediment removal by jet-vac equipment.
|-
|rowspan="3"|'''Vegetated BMPs'''
|-
|For vegetated BMPs, consideration should be given to what source of water will be drawn upon for irrigation during the establishment/warranty period, how it will be delivered to the BMP (e.g., is equipment with sufficient volume and pressure available?), and in some cases an irrigation system should be part of the BMP design (e.g., [[green roofs]]).
|-
|For vegetated BMPs in high pedestrian traffic areas, consider the need for walkways or stepping stones and barriers to help limit foot traffic to designated portions of the BMP, or discourage it altogether if it is causing [[vegetation]] [[Maintenance, Rehabilitation and Repair|maintenance issues]].
|-
|rowspan="2"|'''Underground Pretreatment or BMPs'''
|-
|For underground pretreatment devices or BMPs, the associated manholes or maintenance hatches should be close to a drivable surface/path that can support the heavy vehicles needed for sediment removal maintenance (e.g., hydrovac trucks) and consider installing a staff gauge or graduated measuring tape to allow sediment depth to be assessed visually from the ground surface, without having to enter the confined space.
|-
|rowspan="3"|'''[[Green Roofs]] and [[Blue roofs|Blue Roofs]]'''
|-
|Safe and efficient means of accessing and exiting a [[green roof]] or [[Blue roofs|blue roof]] site for installation, inspection and maintenance is a primary consideration as it will influence the time and effort required to transport tools, equipment and materials to and from the site.
|-
|For [[green roofs]] and [[Blue roofs|blue roofs]], tie-off points for ladders and personal fall protection safety equipment should be incorporated in the roof design for use by individuals performing inspection and maintenance work.
|-
|rowspan="4"|'''General Considerations'''
|-
|Lockable caps on [[wells|monitoring wells]] and sub-drain clean-out standpipes to prevent unauthorized access, tampering, or vandalism.
|-
|Features for taking the BMP off-line or draining stored water by gravity to improve ease of inspection and sediment removal maintenance tasks.
|-
|[[Inlets]] should be readily accessible from surface conveyances, catchbasins, manholes or access hatches to avoid the need for specialized equipment for inspection (e.g., closed circuit or remote controlled cameras).
|-
|}
==Inclusion of Planting Plans==
[[File:Kortright Planting Plan.PNG|700px|thumb|An example of a [https://wikidev.sustainabletechnologies.ca/images/a/ac/Bio-Retention_Cell-Cell_A_planting_plan_20130415.pdf TRCA project Planting Plan] for a [[Bioretention]]/[[Bioswale]] BMP located at the Kortright Centre, in Vaughan, ON. listed with appropriate [[plants]], [[grasses]], [[trees]] and [[shrubs]] species for the area with their scientific and common names listed along with the quantity to be planted, plant type, site and condition characteristics, flowering assemblages and colours and mature height (Source: TRCA, 2013.)|link=https://wikidev.sustainabletechnologies.ca/images/a/ac/Bio-Retention_Cell-Cell_A_planting_plan_20130415.pdf]]
All vegetated BMP designs should include planting plans that specify [[Plant selection|species]] that can tolerate both wet and dry conditions and, for BMPs that will receive de-icing salt laden runoff during winter, species
that are salt tolerant. Further consideration should be given to species that are both pollution and soil compaction tolerant given the location of many BMPs along roadways and near public spaces. Where possible, planting should done during the wettest seasons/months of the year (e.g., early spring and mid-to-late fall) to help minimize the need for irrigation (and staff time and equipment) during the establishment/warranty period. Use of drought-tolerant and native species will help minimize or eliminate the need for irrigation during the operating phase of the BMP life cycle. Good vegetation cover on the surface and side slopes of BMPs helps to maintain infiltration function, contributes to runoff volume reduction function through evapotranspiration, and helps prevent erosion of soil and/or mulch cover from flowing overland water.
Both common and botanical (i.e., species Latin name) names should be used on [[Planting design#Planting plans and specifications|planting plans]] so that inspectors and maintainers of the vegetation are better able to recognize or develop the means of recognizing the plants in the field and distinguishing them from pervasive weeds. Planting plans should also specify the planting method (e.g., seed vs. sod) and plant or container size (e.g., saplings vs. caliper tree; plugs vs. pots; bare root vs. root ball). Any deviations from the planting plan or species substitutions should be noted on as-built drawings/planting plans.
All construction contracts that include [[vegetation]] should specify a minimum two (2) year warranty period (i.e., establishment period) for the plants, which begins after planting is completed, and ends when the BMP is assumed by the owner. Over the warranty/establishment period the contractor is responsible for routine maintenance tasks (e.g., watering, weeding, and sediment and trash removal).
Consideration should be given to specifying a phased approach to planting in construction contracts, in which planting occurs in two stages (e.g., fall and the following spring; spring and the following fall) to help ensure the full palette of plants specified in the plan are available. Thereby, any failed plantings from the first stage of planting are sure to be replaced in the second. If many or all plantings of a certain species do not survive the first phase, they can be substituted with another more tolerant or suitable species in the second (A list of suitable shrubs, trees, graminoids, etc. can be found on our [[Plant lists]] page).
==Inclusion of Sediment Removal Plans==
As mentioned previously, it is recommended that, where possible, [[pretreatment]] devices be included in BMP designs that help retain coarse sediment and debris in an easily accessible location before it enters the BMP itself. However even with pretreatment devices in place, fine sediment will inevitably reach the BMP and accumulate over time. LID BMP designs need to consider how sediment can be removed from associated manhole sumps, pretreatment devices, inlets and pipes, and include adequate features and routes for access by necessary equipment.
<br>
[[File:MaintenancePICP.png|thumb|450px|Vehicle used for vacuum maintenance of [[permeable pavements]] (Source: STEP).]]
{|class="wikitable" style="width:750px;"
|+'''Sediment Removal Equipment per BMP Type'''
|-
!<br>'''LID BMP Type'''
!<br>'''Equipment Required for Sediment Removal'''
|-
|'''[[Permeable pavement|Permeable Pavers]]'''
|For permeable pavements, regenerative air sweeper (for routine maintenance) or vacuum sweeper (for rehabilitation) equipment (e.g., street cleaner trucks or more compact units) will be needed, so designs should allow access to the majority of the surface by necessary equipment (e.g., minimize obstructions and sharp corners);
|-
|'''[[Inlets]], [[Vegetated filter strips|Grass filter strips]], [[gravel diaphragms]], [[Check dams]], and [[Forebays]]'''
|Use of a vacuum sweeper truck with hose attachment, soil blower truck (operated in reverse), sidewalk vacuum or hand tools (e.g., rakes and shovels) are options for each of these [[Pretreatment|pretreatment devices]] and flow controlling/detention devices.
|-
|'''Vegetated BMPs'''
|For removing sediment from the filter beds of vegetated BMPs, use of a vacuum truck with hose attachment, soil blower truck (operated in reverse) or hand tools are options that can minimize the need to remove established [[vegetation]], while use of a small excavator or backhoe can also be effective, but will require vegetation removal and transplanting (where feasible) or replacement after the work is completed.
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|'''Underground BMPs'''
|For underground BMPs (e.g., [[Infiltration chambers|underground infiltration systems]], [[soil cells]]) and associated [[pretreatment]] devices (e.g., manhole sumps, [[Oil and grit separators|hydrodynamic/oil and grit separators]], isolator rows, [[forebays]]), and in-line filters, hydro-vac trucks will likely be needed.
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<br>
For underground conveyances (i.e., catchbasins, manholes, [[pipes]]), BMPs, [[pretreatment]] devices, and in-line [[Media filters|filters]], sediment removal often requires crews performing the work to enter confined spaces. Contractors or staff performing the work must have confined space entry training to satisfy occupational health and safety requirements ([https://www.ontario.ca/laws/regulation/050632#:~:text=(1)%20Every%20worker%20who%20enters,632%2F05%2C%20s. Ont. Reg. 632/05 – Confined Spaces Regulation]). <br>
How the material removed from conveyances, LID BMPs, [[pretreatment]] devices and in-line filters will be safely and sustainably managed also needs consideration. Due to the small drainage area of most LID BMPs, the rate at which they accumulate sediment and associated contaminants tends to be low in comparison to centralized stormwater treatment facilities like [[SWM ponds|stormwater ponds]] or detention chambers/tanks that receive drainage from much larger areas. As a result, the potential for sediment accumulated in LID BMPs to qualify as contaminated according to [https://www.ontario.ca/page/soil-ground-water-and-sediment-standards-use-under-part-xv1-environmental-protection-act Ontario Brownfields Regulation 153/04 standards for soil and sediment (Ministry of the Environment, 2011)<ref>Ministry of the Environment. 2011. Soil, ground water and sediment standards for use under Part XV.1 of the Environmental Protection Act. This document provides Ontario’s soil, ground water and sediment standards effective July 1, 2011. PIBS # 7382e01. https://www.ontario.ca/page/soil-ground-water-and-sediment-standards-use-under-part-xv1-environmental-protection-act</ref>] is low. <br>
Most often, contractors or staff performing sediment removal maintenance procedures will be cleaning multiple BMPs and pretreatment devices at multiple sites on any given day. At the end of the day, the mixture of material collected either manually, or by vacuum equipment (e.g., regenerative air or vacuum sweeper, vacuum/soil blower truck, hydro-vac truck) will include a mixture of re-usable, recyclable and non-recyclable constituents. In order to recover reusable and recyclable materials and minimize the volume of material needing to be managed otherwise, the mixture should be screened to isolate trash (for recycling or disposal), natural debris and [[mulch]] (for composting), and [[gravel]] - to pebble-sized [[aggregates]] (for washing and re-use) from finer (i.e., [[sand]] - to [[Texture|clay-sized]]) material. The sand- to clay-sized material (i.e., material passing a 2 mm diameter ([https://www.endecotts.com/faq/sieves-and-calibration/american-standard-test-sieve-series-astm/ ASTM No. 10]) sieve) should then be assessed and managed in accordance with [https://www.ontario.ca/laws/regulation/900347 provincial regulations (O.Reg. 347)].
[[File:Key Design and Plan Review Considerations Schematic.png|thumb|600px|Recommended process for determining reuse and disposal options for sediment from stormwater management BMPs. [https://sustainabletechnologies.ca/app/uploads/2018/04/SWMFG2016_Guide_April-2018.pdf Source: Inspection and Maintenance Guide for Stormwater Management Ponds and Constructed Wetlands (TRCA and CH2M, 2016)]<ref name="example1">Citation: Toronto and Region Conservation Authority (TRCA) and CH2M Canada. 2016. Inspection and Maintenance Guide for Stormwater Management Ponds and Constructed Wetlands. Toronto and Region Conservation Authority, Vaughan, Ontario. https://sustainabletechnologies.ca/app/uploads/2018/04/SWMFG2016_Guide_April-2018.pdf</ref>. <br>
<small>'''Note:''' This flow chart does not depict MECO policy but rather a recommended approach based on TRCA’s understanding of current MECP operational practices.</small>]]
Laboratory testing to determine if beneficial reuse (e.g., spreading on landscaped areas or blending with other constituents for use as a soil conditioner) of the remaining sand- to clay-sized constituents is an option that should be considered. Determining beneficial reuse options for all constituents of the accumulated material could provide substantial savings in terms of costs associated with transporting and managing the material off-site. For more detailed guidance on what types of testing should be done on sediment accumulated in SWM BMPs and what standards to apply to determine when beneficial re-use is an option, refer to [https://sustainabletechnologies.ca/app/uploads/2018/04/SWMFG2016_Guide_April-2018.pdf Chapter 9 of the Inspection and Maintenance Guide for Stormwater Management Ponds and Constructed Wetlands] (TRCA and CH2M, 2016)<ref name="example1" />. The following flow chart (to the right of the page) provides an overview of the process recommended in the aforementioned guide for determining sediment reuse and disposal options.
===Recommended Lab Testing for Sediment Quality===
The selection of sediment quality analysis parameters should reflect the Contributing Drainage Area's (CDA) land use characteristics and reported spill history. The following are the suggested minimum lists of analytes that would be suitable for sites with no history of point source contamination. It is recommended that the [https://www.ontario.ca/page/report-pollution-and-spills MECP be contacted to determine if any spill events] or other site specific circumstances would require additional analytes as well. The following step-by-step process would provide the data needed to evaluate the feasibility of beneficial use of the sediment or landfill disposal options.
====1. Leachate Test====
As required by [https://www.ontario.ca/laws/regulation/900347 O.Reg. 347], testing of leachate toxicity by the Toxicity Characteristic Leaching Procedure (TCLP), establishes whether or not the sediment is hazardous waste, which would then require proper disposal at a hazardous waste facility. The TCLP uses an acetic acid solution designed to simulate a possible worst-case leaching conditions scenario that could occur on a given study site that contains contaminated soils, or any other organic matter that will degrade over time (putrefaction) (Intrakamhaeng, et al. 2019<ref>Intrakamhaeng, V., Clavier, K.A., Roessler, J. G., and Townsend, T. G. 2019. Limitations of the toxicity characteristic leaching procedure for providing a conservative estimate of landfilled municipal solid waste incineration ash leaching, Journal of the Air & Waste Management Association, 69:5, 623-632, DOI: 10.1080/10962247.2019.1569172</ref>. This information is typically required by the MECP as a key first step in characterizing sediment. It may be advisable to conduct this analysis concurrently with Step 2 ([https://www.ontario.ca/laws/regulation/040153 O.Reg. 153/04 Bulk Soil Analysis]) so that samples for both tests can be collected during the same visit.
====2. O.Reg. 153/04 Bulk Soil Analysis====
Bulk soil analysis based on the [https://www.ontario.ca/laws/regulation/040153 O.Reg. 153/04 Standard] is carried out to evaluate whether sediment is suitable for beneficial use or requires landfill disposal. The OMOECC has, on a case-by-case basis, accepted the contaminant thresholds in O.Reg. 153/04 Table 1 as a basis for classifying sediment as
inert. Inert sediment can be used off-site without regulatory approval. Sediments that exceed Table 1 soil standards would require a risk evaluation to identify potential beneficial use options according to the figure to the right. <br>
The following is a base list of bulk soil analytes to be tested. It may be necessary to include additional analytes if land use activities in the CDA or past spills are believed to have introduced contaminants that are listed in the Standards but not included in this list.
*Trace metal scan including hot water extractable boron
*Cyanide
*Polycyclic Aromatic Hydrocarbons (PAHs)
*Petroleum Hydrocarbons (PHCs)
*Sodium Adsorption Ratio (SAR)
*Electrical Conductivity (EC)
*Particle Size Distribution (PSD)
====3. Topsoil Analysis and Certified Crop Advisor Report for Beneficial Use Evaluations====
The topsoil analysis would only be conducted if the O.Reg. 153/04 bulk soil tests determine that the sediment does not require landfill disposal due to high contamination levels. Topsoil analysis would be necessary to demonstrate that amending the receiving site soils with the sediment would provide a benefit to the soils, as required by the [https://www.ontario.ca/laws/statute/02n04 Nutrient Management Act], without inhibiting plant growth.
The list of analytes to be considered includes:
*Trace metal scan including hot water extractable boron
*SAR
*EC
*pH
*Soil Organic Matter (OM)
*Extractable (i.e., Available) Nutrients
*PSD
==References==