new requirements for stormwater management€¦ · water so pervious paving is not a desirable...

New Requirements for Stormwater Management Online Survey Results

19375859

September 2016

Table of Contents

1.0 Participation ............................................................................................................................. 2 2.0 Experience with Types of Housing ........................................................................................... 3 3.0 Experience in Municipalities .................................................................................................... 4 4.0 Drain Paved Areas to Topsoil or Vegetation ........................................................................... 5

4.1 Familiarity with Practice ............................................................................................... 5 4.2 Perceived Barriers ......................................................................................................... 5 4.3 Question Responses ...................................................................................................... 6

5.0 Pervious Paving ........................................................................................................................ 8

5.1 Familiarity with Practice ............................................................................................... 8 5.2 Perceived Barriers ......................................................................................................... 8 5.3 Question Responses ...................................................................................................... 9

6.0 Drain to Sump ......................................................................................................................... 11

6.1 Familiarity with Practice ............................................................................................. 11 6.2 Perceived Barriers ....................................................................................................... 11 6.3 Question Responses .................................................................................................... 12

7.0 Impervious area...................................................................................................................... 14

7.1 Question Responses .................................................................................................... 14 8.0 Topsoil Depth ......................................................................................................................... 16

8.1 Perceived Barriers ....................................................................................................... 16 8.2 Question Responses .................................................................................................... 16

9.0 Disconnecting Roof Leaders ................................................................................................... 19

9.1 Familiarity with Practice ............................................................................................. 19 9.2 Perceived Barriers ....................................................................................................... 19 9.3 Question Responses .................................................................................................... 20

10.0 Rain Gardens ........................................................................................................................ 22

10.1 Familiarity with Practice ........................................................................................... 22 10.2 Perceived Barriers ..................................................................................................... 22 10.3 Question Responses .................................................................................................. 23

11.0 Rockpits ................................................................................................................................ 25 11.1 Familiarity with Practice ........................................................................................... 25 11.2 Perceived Barriers ..................................................................................................... 25 11.3 Question Responses .................................................................................................. 26

12.0 Cisterns ................................................................................................................................. 28


13.0 Site-Specific Studies ............................................................................................................. 31


14.0 Additional Practices ............................................................................................................. 34

14.1 Question Responses .................................................................................................. 34 15.0 Additional Comments .......................................................................................................... 36

15.1 Question Responses .................................................................................................. 36 Appendix A: Survey Participants ................................................................................................. 38

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New Requirements for Stormwater Management Online Survey Results

Municipalities across Metro Vancouver have committed to phasing in new stormwater management requirements1. The requirements will reduce pollutants in stormwater runoff and reduce the volume of stormwater runoff on single-lot residential developments. This will improve watershed health and protect habitat for fish and other wildlife. The requirements are designed for single-lot residential development, which includes new detached homes, duplexes, and triplexes where an existing house is being demolished and replaced or where an infill dwelling is added to an existing lot. Subdivisions and greenfield developments would not be included as they are generally covered by existing municipal requirements. Each municipality will specify how the requirements should be achieved on residential lots through their bylaws. To support consistent implementation and best practices, Metro Vancouver is suggesting specific practices for achieving the minimum requirements. It is anticipated that most municipalities will adopt these practices, except in areas where conditions prevent beneficial implementation or where there are more stringent stormwater management requirements already in place. Between January and August 2016, Metro Vancouver consulted with homebuilders, landscapers, landscape architects, architects, developers and other industry stakeholders who build or landscape single-lot residential development. Participants were asked for feedback on the suggested practices and to identify how best to support industry to comply with the requirements. As part of these consultation efforts, Metro Vancouver hosted an online survey from May 16 to July 31, 2016 to gather input on the new requirements for stormwater management. This survey was part of a series of consultation activities directed at homebuilders, landscapers, landscape architects, architects and other industry stakeholders who build or landscape single-lot residential development. The survey was advertised primarily through existing industry association newsletters as described in the Engagement Summary Report, August 2016. In addition, the survey was promoted to over 200 homebuilders through a targeted email and calling campaign. The survey included 41 questions exploring familiarity with suggested practices, potential barriers to employing these practices, and suggestions for overcoming the barriers. The questions 1 The requirements reflect the Integrated Liquid Waste and Resource Management Plan (ILWRMP) Strategy 1.1 (d) to establish region-wide baseline criteria for on-site rainfall management, including variations for localized geology, rainfall and watershed conditions.

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also explored additional suggestions for practices that may reduce the quantity or improve the quality of stormwater runoff. The questions and the responses to the survey questions are provided by topic below.

1.0 Participation

What is your profession? (45 responses) The majority of survey respondents (66%) were builders or developers. This likely reflects the fact that the survey was promoted specifically to homebuilders. A full list of participants can be found in Appendix A.

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2.0 Experience with Types of Housing

What types of housing do you usually work on? (45 responses) As a group, respondents have experience in all types of single-lot residential development considered in the requirements. Some respondents work on more than one type of housing.

Other types of housing noted by respondents

Range of housing types, neighbourhood planning

Single family, multi-family, commercial, industrial and institutional

Townhouse

Condos

Commercial/Mixed Use

Schools and other institutional properties

High/mid-rise apartments, condos, and townhomes

Occasionally work on single-family housing. Mostly public realm projects.

Mid-rise

We don't do a lot of housing work, but are currently helping develop single homeowner tools for North Vancouver and have done a number of other stormwater-related projects

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3.0 Experience in Municipalities In what municipalities do you do most of your work? (45 responses)

As a group, respondents work in all municipalities within the GVS&DD and most respondents work in more than one municipality.

Municipality Number of respondents working within

Anmore or Belcarra 2

Burnaby 17

Coquitlam 11

Delta 7

Langley (City and Township) 10

Maple Ridge 8

New Westminster 18

North Vancouver (City or District) 9

Pitt Meadows 2

Port Coquitlam 6

Port Moody 3

Richmond 6

Surrey 18

Vancouver 25

West Vancouver 7

White Rock 17

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4.0 Drain Paved Areas to Topsoil or Vegetation

4.1 Familiarity with Practice How often have you included draining all paved areas to vegetation and/or topsoil in your projects? (43 responses) The majority of respondents (93%) indicated they are familiar with or have used the practice of draining paved areas to topsoil or vegetation. 44% of respondents regularly use this practice in their projects.

4.2 Perceived Barriers Do you see any barriers to including this practice in your projects? (43 responses) Approximately half of respondents (53%) did not see any barriers to draining paved areas to topsoil or vegetation in their projects.

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4.3 Question Responses

What are the barriers to draining all paved areas to vegetation and/or topsoil in your projects? (19 responses) What would help to overcome these barriers? (17 responses) Of the respondents who indicated they saw barriers to draining all paved areas to vegetation and/or topsoil, the barriers they noted and their suggestions for addressing the barriers are summarized below.

Barriers Suggestions for addressing these barriers

Grading issues don't allow this to work in many sites.

Flat land.

Sloping properties, driveway grades in regards to garage elevations etc.

Nothing in certain areas.

The driveway as it slopes onto the sidewalk or street is difficult, swales are not aesthetically pleasing and create standing water problems. It is also expensive. About $5K per average single detached home.

Make an exception for the driveway water to flow onto the street or sidewalk.

For driveways it will depend on elevations i.e. side-to-side slopes.

Available land, ratio of impervious to pervious area.

Regulatory requirements.

Water running off paved areas to soil will create mud.

Design guidelines and specification details

Too much volume to be handled this way – excess water in planted areas may lead to plant failure – planted area maintenance, especially for 'rain gardens' in public areas – public concern about mosquitos.

The pervious hard surfaces with backup drainage system in planted areas by installing storm drain system but that increase costs – provide information to educate the public and encourage community groups to have 'hands-on' events to help the public.

Municipal regulation.

City bylaws. City bylaws need to be changed.

Cost and municipal regulations. Examples of past projects.

Depending on the lot size or access to a green belt/space to drain to (city lots), cost may be a factor.

Affordable drainage products and materials.

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It is dependent upon the soils, and proximity to structural walls which in the case of small residential lots is a constraint.

Soil profiles.

Standing water next to foundations.

Engineering departments or civil engineering consultants often follow a 'collect-and-convey' paradigm.

Standard details from MV, performance targets, and a clear priority for such Low Impact Developments – are we aiming for water quality improvement (therefore require vegetation) or quantity (no veg required)? Quality priority would likely take place in offsite boulevards, parking lots, industrial, commercial and mixed zoning where there is more space. Quantity controls best match single-lot residential. Identifying these priorities and connecting them to land use will help the designer meet performance requirements.

Sites are 90+% on slab construction with buildings and hard scale taking up the majority of the site.

Requirements for using green roof technology, on site storage, and innovative design.

This works best on large sites and for site specific conditions. Grading and subsoil are considerations. Also this necessitates a limited planting palette and with planting areas becoming rain gardens primarily. May be more suitable for some sites than others.

Most important to manage the water. There are a number of tools to accomplish this. One method shouldn't be given priority over another.

Limits design, possible flooding issues and sedimentation.

Treat water holistically across the whole site, encourage water capture and reuse.

It depends on the size, type and design of the vegetated area relative to the size of the contributing paved area, and the underlying soil infiltration rate.

Guidance regarding sizing of vegetated area relative to contributing paved area.

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5.0 Pervious Paving

5.1 Familiarity with Practice How often have you included pervious paving in your projects? (42 responses) The majority of respondents (98%) indicated they are familiar with or have used the practice of installing pervious paving. 26% of respondents regularly use this practice in their projects.

5.2 Perceived Barriers Do you see any barriers to including this practice in your projects? (42 responses) Approximately half of respondents (55%) did not see any barriers to installing pervious pavement in their projects.

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5.3 Question Responses What are the barriers to using pervious paving in your projects? (19 responses) What would help to overcome these barriers? (13 responses) Of the respondents who indicated they saw barriers using pervious paving in their projects, the barriers they noted and their suggestions for addressing the barriers are summarized below.


Placement.

Cost. (Noted by 3 respondents)

Cost. If pervious paving were cheaper.

Expense and infrastructure required to relieve the system of excess water.

Costs may be five times the cost of standard paving systems.

Added cost. Also the products may not be as durable and are higher maintenance.

Find a product that isn't more expensive and is durable.

Cost over poured concrete and more importantly, design guidelines don't allow pavers in many subdivisions.

Cities and design consultants allowing pavers.

The added cost to the homeowner compared to the usual pavers, asphalt and concrete.

Work with manufacturers to reduce production costs.

Usually barriers are related to a) cost of the paving solution vs. standard treatments or b) site's soils are not likely to infiltrate much water so pervious paving is not a desirable solution.

More information on many different suppliers to help encourage competition and a cost-friendly industry. Provide information on soil characteristics and when to use these solutions.

Cost. Availability of contractors.

Too many sloped sites; flat driveways work better.

More flat land.

Pervious paving requires regular cleaning (of the pores) to ensure function.

Need multiple low-impact techniques.

Base preparation is frequently ignored by the installer. Cost is not palatable to clients.

Bonding for proper installation of base preparation.

Poor subsoil conditions, engineering requirements that put infiltrated water into a pipe, and poor maintenance practices post-development that ruin performance over time.

Better engineering requirements that foster reuse/long term storage on-site and requirements for maintenance.

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Performance of porous paving diminishes over time. Also many soils in this region have low permeability.

More education and case studies of proven examples.

Perception is that maintenance is an issue, so owners are afraid to adopt.

Education, example projects showing longevity of materials.

Pervious paving, no matter what type can be problematic. Pavers sink and settle becoming a warranty concern. Pervious paving can cause wash out and sink holes undermining the surface.

Nothing.

Feasibility depends on soil infiltration rate, quality of runoff (e.g. high suspended sediment), layer build up, and whether there are underdrains.

Guidance regarding the above.

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6.0 Drain to Sump

6.1 Familiarity with Practice How often have you included collecting runoff from paved areas and draining through a sump prior to discharge to the storm drain? (38 responses) The majority of respondents (95%) indicated they are familiar with or have used the practice of draining through a sump. 42% of respondents regularly use this practice in their projects.

6.2 Perceived Barriers Do you see any barriers to including this practice in your projects? (36 responses) Approximately half of respondents (56%) did not see any barriers to collecting runoff and draining through a sump in their projects.

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6.3 Question Responses What are the barriers to collecting runoff from paved areas and draining through a sump prior to discharge to the storm drain in your projects? (11 responses) What would help to overcome these barriers? (6 responses) Of the respondents who indicated they saw barriers to collecting runoff from paved areas and draining through a sump prior to discharge to the storm drain, the barriers they noted and their suggestions for addressing the barriers are summarized below.


Not sure how driveways will feel for customers.

A sump has limited capacity. Back-up systems and reliance on typical subsurface storm drain system.

High costs of sumps. Requirement for long-term maintenance.

City to provide tax relief or $ incentives to install them.

Adds an extra step and cost (collection pipes).

Adds load to storm drainage system.

Cost and maintenance. Challenges with approvals and installation.

Make sure civil engineers and plumbers are not required to design or install. This would make it onerous for the owners. Also, please provide municipalities with online printable PDF details that can be downloaded and cut and pasted on to a drawing. Make sure all municipalities use the same detail otherwise it will be difficult to customize this for every different city. Avoid plumbing inspections.

Often somewhat costly.

Installing the driveway with a swale to prevent water from flowing onto the street is not aesthetically pleasing and is time consuming. It also creates standing water problems when there isn't enough slope to work with.

Make an exception for driveways.

Long dry summers have made runoff a precious resource – it should be used to water landscaping and/or replenish groundwater, not discharged to storm sewers except when necessary for safety.

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It depends on size of sump vs contributing area, and having an informed homeowner/municipal officials to perform regular inspections and clean-outs.

Is the intent for this to be a concrete sump that allows sediment to settle out before the stormwater enters the municipal system? Are other below ground tools being considered? E.g. infiltration gallery/soak away, infiltration chamber, below ground cistern.

Often this solution is under the purview of the Civil Engineer.

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7.0 Impervious area

Do you have any comments on using 70% total impervious area as a default assumption? (22 responses) 7.1 Question Responses The table below summarizes participant answers related to using a 70% impervious area as a default assumption.

Comments

If downspouts are disconnected and flow into a rock pit, the roof area should not be calculated into the equation. On small lots the 70% target would not be achievable.

Small lots can often have up to 75% lot coverage between house, drive/walk ways and patios.

What if the 70% limit is exceeded?

No, other than aesthetics.

70% impervious means 30% pervious. That doesn't sound like very much.

I believe this is reasonable.

It becomes necessary to install expensive porous paving systems. Increases the cost of development.

It should be done on all jobs.

City of North Vancouver receives lots of rain, I don't know whether or not this will work.

Depends how the 70% is calculated. Does that include the roof?

This sounds challenging in urban areas (e.g. most of Vancouver). How would you calculate a green roof with minimal soil depth?

Likely to be less in most urban locations.

As long as drainage into landscaping is planned concurrently with overall site planning, a 70:30 (2.3:1) ratio of impervious to landscaping is generous for absorbing all light to medium rains. Infiltration in North Delta is virtually total up to a ratio of about 5:1. But if a house is poorly sited (e.g. on the lowest ground on the lot) – and drainage left as an afterthought – then we can't take full advantage of the infiltration capacity of landscaping.

Like any assumption, it may not always apply.

No if pervious paving can be included in the 70%. Otherwise this limit promotes use of lawn areas over planting beds.

Seems arbitrary. If 100% of the site is impervious but it's being collected and reused, it isn’t a problem.

An effective impervious area target would be more appropriate. As long as the site manages the runoff it produces the absolute impervious area is not as relevant from a stormwater perspective.

Should be 60% or less. The larger footprint of house and paved surfaces reduce the amount of area for natural infiltration.

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Comments

As degradation occurs to a watershed when only 10-20% of its catchment area is impervious, the reality of 70% in urban areas is already well beyond it. As part of this statement, I'd include a range rated as 'best, good, minimum, etc.'

That is higher than what we are used to.

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8.0 Topsoil Depth

8.1 Perceived Barriers Do you see any barriers to including a minimum topsoil depth of 450 mm in your projects? (37 responses) The majority of respondents (59%) did not see any barriers to including a minimum of 450 mm of topsoil in their projects.

8.2 Question Responses What are the barriers to including a minimum topsoil depth of 450 mm in your projects? (13 responses) What would help to overcome these barriers? (10 responses) Of the respondents who indicated they saw barriers to including a minimum topsoil depth of 450 mm in their projects, the barriers they noted and their suggestions for addressing the barriers are summarized below.



More costs, removal of existing soil and replacement of topsoil.

Cheaper dump sites and cheaper top soil.

Cost. Reduced cost. City of Vancouver Landfill compost should be free, or nearly so, this would help to reduce the cost of rich, organic top soil.

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Expensive and requires extra fill material to be removed from sites and trucked off to landfill areas which creates a carbon footprint. Also the manufacture and trucking of extra top soil has a carbon footprint.

Top soil is porous, but so is sub soil, depending upon the condition of the sub soil. May not be beneficial to remove a sandy fill to replace with a sandy topsoil. Seems to be a site-specific requirement.

Revise the requirement for 450 deep top soil to be a site-specific requirement, if the subsoil has a low hydraulic conductivity then replace it with a sandier material. The kinds of replacement top soil are critical. High organic material in these trenches will end up as an impervious layer. Be careful when demanding this increase in depth.

The only barrier might be cost to the homeowners, and it may not be necessary in all areas.

Flexibility in selection of tools based on site conditions, budget, etc.

Cost of additional topsoil.

Not necessarily needed in *all* areas. Oftentimes turf areas can be 300mm (or have a freer draining sub layer) with 450mm in all vegetated areas.

Who monitors the 450 mm depth? Civil engineers may not know anything about planted areas. Landscape architects understand drainage and planted areas but are subject to the limits of their contract. Municipal staff are overloaded and sometimes don't get the necessary support from senior staff to do the job right.

Over time organic material decomposes and will create a very uneven yard and standing water problems.

Allow the use of inorganic material like sand that wouldn't decompose over time.

Depending on the type of construction, deeper topsoil could mean larger impacts to the existing and adjacent sites.

Better understanding of the existing site and soils.

How are you going to define "topsoil"? Suggest changing "topsoil" to "growing medium" as defined by the BC Landscape Standard to ensure uniformity and a specification that is enforceable. Also, this

#1 Change "topsoil" to "growing medium” (as defined in the BC Landscape Standard). #2 Develop a good cross section detail for 450mm growing medium adjacent to concrete/asphalt/paver walkways as well as

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depth of growing medium adjacent to pavement structures is difficult to achieve when compacted gravels are typically only 300mm deep. You could have compaction problems.

adjacent to curbs. Make this publicly available.

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9.0 Disconnecting Roof Leaders

9.1 Familiarity with Practice How often have you included disconnecting downspouts (roof leaders) in your projects? (36 responses) The majority of respondents (78%) indicated they are familiar with or have used the practice of disconnecting roof leaders. 16% of respondents regularly use this practice in their projects.

9.2 Perceived Barriers Do you see any barriers to including this practice in your projects? (36 responses) There was a 50/50 split between respondents who saw barriers and those who did not see barriers to disconnecting roof leaders in their projects.

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9.3 Question Responses What are the barriers to disconnecting downspouts (roof leaders) in your projects? (17 responses) What would help to overcome these barriers? (11 responses) Of the respondents who indicated they saw barriers to disconnecting downspouts in their projects, the barriers they noted and their suggestions for addressing the barriers are summarized below.


What to do with run off; can’t have green roof on all roofs?

Not familiar with this practice.

High rainfall area, with impermeable soil conditions on hill sides.

Point flow across property lines is problematic.

Downleader disconnection is often not used properly, with roof water directed onto public trails and walkways where it can result unsafe walking surfaces.

Municipal regulation often prohibits downspout disconnection.

Flooding of foundations and compromising of footing drains. It is necessary to get water away from the buildings. Concerned that single family lots cannot support the volumes of water from downspouts.

Down spouts could flow to underground cisterns but never flow overland.

#1 Poor siting of buildings (e.g. on lowest ground of property), so that disconnected downspouts may present a risk to the structure. #2 Deep in-ground basements are more vulnerable than slab foundations, and they also remove a large amount of potential groundwater-storage capacity. #3 When buildings are in close proximity to each other, disconnected downspouts from one can impact another – unless there's coordination such as agreeing on a shallow swale between the buildings.

More active involvement by, and advice from, municipal planners and engineers, on how to best site a building so that its landscaping can take full advantage of roof runoff.

Leaking foundations.

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Not always a place to put the water, either above or below ground.

Better requirements for the capture and reuse of rainwater/grey water for all developments.

This only works if there are suitable conditions for receiving and managing the runoff on the ground (space, grades, infiltration rates). In some settings it will be more feasible to direct relatively clean roof runoff to underground infiltration rockpits or chambers.

Again, flexibility is important in the selection of tools.

This works in some circumstances but not all. Depending on the design of the building and the site available this can be problematic. If this is the preferred method, there should be an opt-out or equivalencies route for alternate approaches.

As above, flexibility and options.

Wash out of landscapes, super saturation of lawn areas.

Redirect the water to a cistern or other water collection device for use as landscape watering when possible.

Need to direct them to areas capable of handling the volume of water likely to occur, and to include a safety overflow catch basin if this volume is too much.

Information on how this sort of system (disconnected, to rain gardens with safety catch basins) would be designed and installed.

Why stop with disconnecting downspouts? Mandate rain barrels.

Have mandatory rain barrel installations on all new developments.

Engineering departments and civil engineering consultants often follow a 'collect-and-convey' paradigm.

Lunch-and-learn outreach programs by Metro Van to firms and internally to municipal engineering departments. This will have a built-in demand as continuing education credits are always welcome.

Cost of building the infrastructure to manage the rainfall water.

Examples of past projects.

Why would you do this?

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10.0 Rain Gardens

10.1 Familiarity with Practice How often have you included rain gardens in your projects? (18 responses) The majority of respondents (83%) indicated they are familiar with or have used the practice of rain gardens. 50% of respondents regularly use this practice in their projects.

10.2 Perceived Barriers Do you see any barriers to including this practice in your projects? (18 responses) The majority of respondents (72%) saw barriers to installing rain gardens in their projects.

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10.3 Question Responses What are the barriers to installing rain gardens in your projects? (14 responses) What would help to overcome these barriers? (8 responses) Of the respondents who indicated they saw barriers to installing rain gardens in their projects, the barriers they noted and their suggestions for addressing the barriers are summarized below.


Not familiar with practice.

Small yards are space restricted.

No room available.

Finding the space on the project for the rain garden.

Municipal variances for these types of measures.

Space to install these on a single family lot or small site can be problematic, it can compromise foundations and footing drains with the excessive stormwater. These increase amounts of standing water when the rain garden eventually silts up. Standing water leads to mosquitoes.

Rain gardens require space. There could be a formula set up if there is X amount of open green space, then X could be devoted to a rain garden, but when the area is so small, removing what could be a nice garden and installing rocks and sedges is not a good thing.

It would be helpful to know the basis of sizing for rain gardens. This footprint size may not be achievable on many properties, as homeowners will consider it a loss of usable space.

Other tools may be more feasible

Where will it go on a standard lot as described? 2.3m wide along the whole width? Between main dwelling and garage? Best option is trees in the rain garden (max evapotranspiration), but with municipal guidelines squishing trees to >3m from foundations and >1m from property line, where to go? Also BC Hydro is now enforcing setback rules from ducting or transformers.

Push on-site shortfalls to off-site boulevard rain gardens; the residential allotment will be the boulevard in front of the residence. Redevelopment or development contribution will include the cost to install stormwater management facility in the boulevard associated with the subject property.

Installations can be inconsistent. Landscape architects and landscape contractors need standards for installation and maintenance.

Get the BC Landscape and Nurseries Association to write landscape standards for use across Canada.

Cost.

On a residential scale, mosquitoes breeding and rat habitat.

#1 Get the rodent population under control on a regional level. The rat problems need to

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be addressed before we start installing rain gardens. #2 Rain gardens aren't going to provide the sort of ecosystem required to keep mosquitoes in check. Consider rain barrels and deep growing medium rather than exposed water on residential lots.

Poor subsurface conditions, varied site conditions like topography and building layout, etc.

Better requirements for use and reuse of rain and grey water on site.

Not appropriate for every site. Also maintenance of these areas is often poor which leads to low public acceptance.

Dedicated maintenance crews and education on how to maintain. Also, as with the other options this should be identified as an option that may or may not work for a site.

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11.0 Rockpits

11.1 Familiarity with Practice How often have you included a rockpit (infiltration trench) in your projects? (36 responses) All respondents indicated they are familiar with the practice of rockpits. 28% of respondents regularly use this practice in their projects.

11.2 Perceived Barriers Do you see any barriers to including this practice in your projects? (36 responses) The majority of respondents (61%) did not see any barriers to installing rockpits in their projects.

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11.3 Question Responses What are the barriers to using a rockpit (infiltration trench) in your projects? (13 responses) What would help to overcome these barriers? (10 responses) Of the respondents who indicated they saw barriers to using a rockpit (infiltration trench) in their projects, the barriers they noted and their suggestions for addressing the barriers are summarized below.


Training and best practices. Seminars etc.

West Vancouver does not allow rockpits.

Some municipal regulations currently ban rockpits.

No bans.

Cost.

Cost, more than $10,000 added to the project.

It's expensive and difficult to install in small yards.

Keep the size of the rockpits smaller.

It all depends upon the infiltration rates of the existing soils. And they eventually silt up.

Allow flexibility in use. It is a good suggestion if the adjacent soils can handle the excess water.

No space available.

#1 Make sure these rockpits do not require civil engineers to design them. These should be landscape elements and not become overly complicated in terms of design or implementation/ approvals/ inspections.

#1 Provide online downloadable PDF details. #2 Ensure no municipality requires plumbing or civil engineering approval/design/ inspections/sign off. This should be something simple that a landscape contractor can do without municipal review. The owner can provide photographs of the installation to the municipality.

Landscape architects would be aware but not the instigator of such best management practices.

Standard detail from a central online clearinghouse of such best management practices.

The volume of the rockpit is more important than the area, and of course this depends on soil infiltration rates, available space, quality of runoff, etc. Infiltration pits seem to be most suitable for clean roof runoff to reduce clogging and maintenance demands over time.

Guidance regarding sizing, suitable locations, suitable runoff quality.

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Aesthetics, site conditions, engineering requirements.

Ability to link systems between homes, better requirements for the reuse and capture of rain and grey water.

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12.0 Cisterns

12.1 Familiarity with Practice How often have you included a cistern in your projects? (35 responses) The majority of respondents (86%) indicated they are familiar with or have used the practice of cisterns. 9% of respondents regularly use this practice in their projects.

12.2 Perceived Barriers Do you see any barriers to including this practice in your projects? (33 responses) Approximately half of respondents (55%) saw barriers to installing cisterns in their projects.

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12.3 Question Responses What are the barriers to including a cistern in your projects? (17 responses) What would help to overcome these barriers? (11 responses) Of the respondents who indicated they saw barriers to including a cistern in their projects, the barriers they noted and their suggestions for addressing the barriers are summarized below.


Rock pits are a more cost effective method of achieving the same result.

Rock pits.

Space to locate cistern.

Cisterns are large, unattractive (typically), and require maintenance over the long term, and have cost and construction implications for the owner.

Ability to reuse the captured water in the home.

Space is a concern for some properties. Thin profile aboveground cisterns are a good option in some cases - e.g. HOG (H2OG) tanks, Murdeau (France), Halstead (UK). The HOG tanks can also fit below decks.

Available space. Depending on the volume these often have to be quite large to remain effective.

Those proposed sizes seem too small to have an actual impact.

Make them larger. Allow owners to use this instead of rain gardens.

Cost and lack of biological activity to ensure quality control, and space.

I suppose this will be a ranked system where these quantity controls will be less incentivized than quality controls.

Cost.

Additional costs of construction and maintenance to the home owner.

Increased Vancouver requirements in many areas of a build are gradually increasing the overall build cost annually.

Expensive, and the amount of water stored is rarely enough for usage. Stored water is contaminated.

Monetary incentives for larger buried cisterns. Also municipal relaxation of policies to allow irrigation from these. We have had pushback from many municipalities who have not allowed their usage due to contaminants in the water source.

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Cost and area available.

It's expensive.

Cost. Subsidies to help pay for cisterns and reuse systems, increased water prices to reflect savings from reusing water.

The increased cost of installation. Landscaping cannot be the last item thought of and people run out of money for a decent install.

If the price of these items are upfront at the beginning of the permit process, it may make acceptance easier.

They are costly. Not sure how to avoid them when retention is required.

I lack the knowledge and skill.

Often concern over 'mosquitos' or other pests. Effective educational tools (and designs) to help overcome these concerns.

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13.0 Site-Specific Studies

13.1 Familiarity with Practice How often have you included a site-specific study and/or professional signoff completed by an engineer, landscape architect or similar professional for stormwater management practices? (35 responses) The majority of respondents (94%) indicated they are familiar with or have used the practice of including a site-specific study and/or professional signoff for stormwater management practices. 46% of respondents regularly use this practice.

13.2 Perceived Barriers Do you see any barriers to including this practice in your projects? (35 responses) The majority of respondents (63%) do not see any barriers to including a site-specific study and/or professional signoff for stormwater management practices.

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13.3 Question Responses What are the barriers to including a site-specific study or professional signoff in your projects? (13 responses) What would help to overcome these barriers? (10 responses) Of the respondents who indicated they saw barriers to including a site-specific study or professional signoff in their projects, the barriers they noted and their suggestions for addressing the barriers are summarized below.


Yes, if applies to infill. We use it when we build a community of homes.

Who has the credentials to sign-off? Have landscape architect learn the science and be able to demonstrate authority in stormwater management.

This is normal for our "septic" project homes, however the cost and additional timing to include a professional in this area will add to the existing problem of permit approval times in the lower mainland.

I don't believe this area should have an outside professional. The municipal districts should over see these requirements completely.

It is time-consuming to have to prepare these documents and I suspect people make-up things to satisfy municipalities. In one instance a certain kind of porous paving had to be described as a rain garden even though it was on a structural roof top. Reports cost clients $ for fees to provide this information. It is usually required at stressful times in projects. Development has become very regulated and time consuming.

Do not require these. Once an engineer or landscape architect takes this requirement on, it requires due care and the time required to research, measure, and document is significant.

Requiring engineers for residential stormwater work will make the process onerous. The list of qualified professionals should be very broad and include landscape architects and landscape contractors who have taken a course.

Provide a stormwater course for landscape contractors.

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Another regulatory step and added cost. Not requiring a professional to have input. Allowing designer/architect to specify along with building design.


Costs and complexity.

Increased cost to homeowner. Ensure no price gouging from the professionals.

It is another soft cost that many clients don't want to pay for.

Not sure what would make this more acceptable.

Adds to the cost of building a house. Some type of property tax credit or incentive that would reduce costs a set amount.

It may not be necessary to have a professional involved in every project. Cost will be an issue for many homeowners.

Simple calculator/online tool for homeowners to select and roughly size their stormwater tools based on their priorities and site conditions.

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14.0 Additional Practices

Have we missed any on-site practices for improving runoff quality or reducing runoff quantity that you feel should be added as options? (35 responses) The majority of respondents (60%) did not see additional on-site practices they felt should be considered as options.

14.1 Question Responses If yes, please describe below. (13 responses) The table below summarizes participant answers to the survey questions related to additional practices.

Comments

Possibly. Plants that have great transvaporative abilities can help.

Industrial lands have a high percentage of impervious area. Require industrial developments to have green roofs to collect and slowly disperse rain water.

Builders and developers need to be shown why containing run-off is so important and how it will reduce the environmental impact of surface water draining into city drains. Otherwise it seems as if the only real outcome is added labour and material costs. Ultimately making housing less affordable.

Use of permeable pavement and contouring of all paved purposes into surface ponding as a landscape features throughout the site.

Retention ponds in the area. Storm water runoff would be diverted to the retention ponds and from there to the storm system.

Living machines, bio-treatment, neighbourhood scale systems as opposed to individual lot, micro hydro alternatives.

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Comments

#1 Permeable pavement is currently used as a catchall phrase but it is rarely actually permeable. The subgrade materials need to be installed properly to make this work. This needs to be looked at in more detail. Otherwise the region will get filled up with "permeable pavement" that doesn't actually allow water infiltration. #2 Artificial turf yards are becoming more and more popular, especially in Vancouver. This should be addressed in terms of it's lack of permeability as well as it's lack of diversity. I believe artificial turf areas should be deemed "impermeable surfaces". #3 There are quite a few properties in Vancouver that have been paved in concrete from edge to edge. Is there some recourse for the municipality to come back after the fact and address these properties that have been "grandfathered" in?

Tree canopy cover can play a major role in reducing the quantity of runoff, and improving its quality. Our well-treed rain gardens manage incredible amounts of stormwater, and even in the absence of an actual rain garden, just trees themselves are outstanding water managers. I think 20% canopy cover should be a standard requirement for single-family properties (and indeed all properties). Homes exceeding the requirement should get a graduated rebate on their municipal property tax, while properties falling below 20% canopy cover should pay a graduated surcharge.

Building specific treatments like green roofs and use of rainwater; block-scale ROW and boulevard treatments, connecting lot/site infrastructure together to effect a greater economy of scales, and improve redundancy/long term resiliency.

Green roofs with enough soil depth are able to manage a decent volume of water.

Absorptive roof structures, storage of rainwater in flat roof, green roof systems. The largest portion of residential stormwater run-off is from roof tops. Perhaps there are ways of keeping water up there at least as temporary storage.

Information should also be included on other solutions such as constructed water quality wetlands (useful on larger sites and also to raise awareness for neighbourhood level solutions) and green roofs.

Above-ground stormwater planters could potentially be incorporated into standard designs for typical foundation planting in single family homes. They don't have to be above-ground if the space below is adequate, if overflow/subdrains are routed properly, and if there is good separation from the foundation drains, e.g. http://www.vwrrc.vt.edu/swc/NonPBMPSpecsMarch11/VASWMBMPSpec9BIORETENTION_clip_image016.gif.

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15.0 Additional Comments

Do you have any other comments related to the requirements or practices? (19 responses) 15.1 Question Responses The table below summarizes additional comments made by participants.

Comments

Get the authorities on board.

Local government won't implement more stringent requirements until MV requires them to address this issue.

Our projects are mainly along the waterfront, so stormwater treatment is typically direct to ocean.

Any new process can be implemented if it is addressed as a simple requirement at permit "intake". I believe all the districts have to look at a more efficient way of receiving plans and confirming the requirements. More professionals added to the process will slow down the process. Building is a major part of our economy and although this process is not about the "permit process" these additional requirements add to slowing the process.

I would question the necessity of this in a dense urban environment.

Builders and developers need to be shown why containing runoff is so important and how it will reduce the environmental impact of surface water draining into city drains. Otherwise it seems as if the only real outcome is added labour and material costs. Ultimately making housing less affordable.

I applaud this initiative. Keep up the great work.

I welcome this initiative, it is well past time to enshrine these practices into our guidelines (or even laws). The low-hanging fruit is found on municipal land however. Instituting a 'de-paving' alleys program seems to me a simple one. Keep it up.

I'd like to reiterate the importance of dealing with effective impervious area and allowing flexibility in tool selection to meet the target volume of stormwater. This seems like it could be a great initiative for helping encourage single family homes manage more stormwater on site. I think that the strongest incentive will be to create a utility fee based on the amount of stormwater runoff that a property generates. The revenue from the fee could partly be used toward homeowner grants that encourage implementation of tools, and toward maintenance and education initiatives.

Given the affordability crisis in the city, these improvements should be implemented with an incentive or credit system that offsets the additional costs. Landscaping is typically done last, with an emphasis on low costs and saving money, adding requirements will certainly add to the final costs and further increase the unaffordability of homes.

Make it standard practice to include rockpits on all single family homes.

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Comments

Glad to see all of this – definitely headed in a good direction. Two additional comments: #1 I can imagine many builders and homeowners being nervous about disconnected downspouts where the ground slopes up from the house. Also, I can imagine homeowners diverging from requirements in the privacy of their back yards. Therefore, I think it may be a good tactic to (a) absolutely require disconnected downspouts in front yards where the ground slopes away from the house to the street and (b) strongly encourage but not require them in other locations. I think this approach, especially at the outset, shows common sense (worst case scenario is that water flows out to the street gutter and into a storm drain there). Once people see how well good landscaping can soak up water, in a totally safe situation where there's zero risk of flooding a structure, then they'll be much more willing to try the technique in other locations. #2 The infiltration performance of landscaping and rain gardens is influenced by type and quantity of vegetation, and by mulching any bare soil with coarse woodchips to maintain soil porosity. For example, a landscape of densely-planted rhododendrons and coarse mulch will soak up water far better than a compacted lawn or some bare soil with a few petunias. I've seen many rain gardens fail because they are planted too thinly and/or with plants that aren’t robust enough. No matter what the soil type and depth, infiltration capacity (speed and total volume) can be vastly improved with thick plantings and woodchip or gravel mulch. Could you include some recommended low-maintenance trees, shrubs and groundcovers, to give builders and homeowners (as well as planners and engineers) an idea of what works well? Dwarf mugo pines, small spirea cultivars, potentillas, azaleas, rhodos, David viburnum, potentillas, bergenias, sword ferns – all these common garden plants and many more will thrive in rain gardens or at the receiving end of disconnected downspouts.

For professionals, don't prioritize one method over another. Be clear about performance requirements and allow for a solution to be customized to the unique characteristics of each site.

All good ideas. Will need specific educational material directed at homeowners, builders, developers, and renters on what their roles are, how the different solutions work, etc.

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Appendix A: Survey Participants

Alchemy Construction Ltd.

attentus landscape architecture

Atti Group

Barrett Group Custom Builders Inc

BC Bigleaf Maple Books

Blue Ocean Construction Inc

Casavilla Development Ltd

Cavalier home ltd

Ciacco Homes Ltd.

Community Development Division at the Township of Langley

Cougar Creek Streamkeepers (North Delta / Surrey BC)

Creus

Essence Properties Inc - GVHBA

F.M. Technical Services Inc.

Fernwood Developments Inc.

GD Nielsen Homes Ltd

Golden Dream Homes Ltd

Halostar Development Corp

Heartwood Developments

Huckleberry Landscape Design

Jeff Henderson Construction Ltd

Jonathan Losee Ltd.

Kindred Construction Ltd.

Lanarc 2015 Consultants Ltd.

Maestro Development

Mercury Contracting ltd.

natural balance home builders

Oceanicflo Construction + Development Corp.

Pantheon Developments

Perry + Associates Landscape Architects

Perkins+Will

PMG Landscape Architects

Portrait Homes Ltd.

Project Mint Developments Ltd.

Recollective Consulting Inc.

Ritchie Construction Ltd.

Seneca Homes

Sopka Development Corp.

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Space2place

Surfside Construction Inc.

SYMBOLIC CONSTRUCTION GROUP LTD.

TQ construction

Triwest Construction Ltd

new requirements for stormwater management€¦ · water so pervious paving is not a desirable...

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