Innovative Stormwater Management at the Property Scale

Innovative Stormwater Management at the Property Scale



you there are many designs to better manage storm water on a property scale this can be done both in new construction and in retrofits rain water becomes runoff as soon as it hits an impervious surface such as a roof or a driveway by retaining reusing and infiltrating rainwater on their property homeowners can reduce the amount of water that makes it to storm sewers this mimics Mother Nature where soil and vegetation slows the movement of water it also allows it to infiltrate into the subsurface reducing the amount of roof runoff that enters storm drains means putting less strain on aquatic ecosystems which bear the brunt of urban storm water this video will show you some examples of innovative stormwater management designs in residential commercial and industrial properties we take you first to beautiful Bowen Island just off the coast of Vancouver BC Bowen Island restricts water use during the dry summer months the properties that are being developed in this area have a restrictive covenant which requires everyone to have a rainwater harvesting system and so that means that all outdoor water use must come from your your storage tanks but in our case the tanks are both providing outdoor water use and our toilet water Kim Stevens is a resident of Bowen Island Stephens harvests his roof water into two large tanks each with a volume of 2,000 gallons or over 8,000 liters these tanks collect rainwater from a 2,400 square foot roof a millimeter of rain falling onto the roof catchment area translates into about one inch of water level in the two tanks gutter guards and downspout filters prevent leaves and other debris from entering the system water then flows through a pipe into the tanks Stevens tanks are connected to the indoor plumbing for the toilet water supply this is the pump then you let sucks the water out of the tanks outside and then feeds it into the system to supply water to the to the toilets and it's a very there goes to pump older toilets use 21 litres per flush Stevens has installed low-flow toilets where just three to six liters of water are used per flush Stevens keeps track of the household water use by checking the level in the tanks this tank is 92 inches in height so all I do now is do a simple measurement from the other side of the the lid and I'll just see how much that's gone down so we're at about 44 inches so it's about half way after whatever it is six weeks of rain free weather this tank is now down about half capacity and that includes our outdoor water use as well as all of our toilet use the water collected in the tanks is clear and ready to use right away one person in a year uses one tank of water so puts it all in context in terms of I know how ways how we size systems and what we actually use those two tanks are more than sufficient to get us through you know a four to six month period both indoor use and our limited outdoor use without having to switch over to the treated water supply the house contains other stormwater features gutter chains direct some of the roof water into the garden if you look at the driveway you'll see that it's granular because that's another part of the restrictive covenant is no paved driveways so that whatever falls on it percolates down and in terms of the garden itself it's a very limited garden area but we highly just use the combination of the soaker hose and hand watering you as we saw on Bowen Island driveways are a great opportunity for homeowners to reduce impervious surfaces on their property conventionally driveways are paved using concrete or asphalt all rainfall that lands on them becomes runoff using an alternative driveway design can allow water and contaminants to infiltrate into the soil this can be done using pavers and grass a ribbon driveway or pervious pavement that directly absorbs water these options are effective ways to reduce the stormwater runoff generated these designs are not only found on houses even your local community center can incorporate stormwater management into its landscaping the South Surrey community center has a specially designed roof the directs roof water down a spout into a rain garden rain gardens create seepage areas where water can infiltrate into a grouping of plants called an artificial bioswale concrete pavers on the parking lot allows some water to infiltrate into the soil below the soil then treats the oil and grease left behind from cars the parking lot is also graded to coax water to flow into the rain garden North Vancouver receives over two meters of rain and snow every year managing and reducing runoff is a big challenge leading the way is the Mountain Equipment co-op retail store this building represents a combination of structures and designs that collects water from the roof parking lot and adjacent road it also detains and filters the contaminated runoff for indoor use downspouts from the roof direct rainwater into a rain garden this is functional and aesthetically pleasing Krystle Campbell is one of the stormwater consultants who help design these features the stormwater management on this site is innovative and unique here behind me is a stormwater rain garden so it collects water from the roof and from part of the parking area and it treats it by moving the water through the Swale through the vegetation and the soil layer it gets filtration and then it is infiltrated into the ground we have a groundwater well that takes water from the ground and reuses it in the toilets signs in the stores bathrooms inform the public about the source of the toilet water and warn that it's not safe to drink most of the contaminants are coming from the parking lot area and so that can have general stormwater contaminants such as sediment total suspended solids it can have oils and grease from vehicles droppings and it can also have metals so as their drink to the rain gardens they get storm water treatment through the vegetation and soil layer just down the street Richard Bose has taken a proactive and hands-on approach to retrofitting his family home what we're going to look at here is some of the things that I managed to do to our home here on what we call a retrofit basis on a single family property one of the things we're doing now green infrastructure cascading systems just like what Mother Nature does starting with the trees the tree canopy the branches that the bark the soil the soil under the soil and then ground so I've kind of tried to mimic the same thing here all the water that lands on the parking lot is collected into the sump there and then there's a pipe that's collected from the sump that runs down in behind the base of this wall so I'm infiltrating all of the water from the parking lot out into the soil but behind the wall the system then comes down the side down here to my first collection sump all the water from the roof of my garage the water that doesn't infiltrate in behind the wall comes into this sump where you can see the gravel bottom so there's a lot of infiltration that's going on just on the water that hits this sump here so during heavy rains if this sump fills up in the ground and the water saturated the water comes out from a pipe that flows down here and flows into my main backyard infiltration system so this system here has allowed me to build the garage and all the parking lot with no connection out to the storm sewer system so after working with the city I got all of the approvals that I needed you know to put that alternative system in place beause also has a rain barrel connected to his house the important thing here is we've had some rain so I've got a little pipe here and not quite full but one of the things – it's important that when your rain barrel fills up you need to empty it to use the water right because you don't want once your rain barrel is full it doesn't do anything for you so I've got the kids all programmed to check the rain barrel come put the hose out on the grass and just empty the rain barrel out on the grass the the water guns are out on the yard so it's been hot lately so they'll use the rain barrel to fill up the water guns and things like that Bo's has detached the downspout from his storm water connection to allow roof water to drain on to the grass it may seem that a grass lawn is a good option to allow infiltration on a property but that's not true when turf is rolled over compacted soil this is common when construction uses heavy machinery the soil is so hard it is as though grass has been laid over concrete unsurprisingly this leads to drainage problems pooling and runoff during heavy rains adding a layer of topsoil can alleviate this problem one of the new standards we're working on is when they do landscaping here we're really trying to encourage developers to use at least 300 millimetres of of organic topsoil because that's been found to be the most effective depth for soil to manage rainwater so I've just dug a bit of a hole here and they're got they they're using well above the 300 millimetre standard of topsoil in here so that's great in addition to thick topsoil you can plant trees urban trees are very important for stormwater management rain is intercepted by the leaves in the trees canopy this reduces and slows rainfall that would otherwise become runoff water also evaporates from the canopy back to the atmosphere research has shown that western red cedar trees intercept any vapo transpire up to 55% of rainfall even without other stormwater designs a large tree can slash your effective impervious area urban trees also provide shade temperature regulation windbreak erosion control wildlife habitat and they act as a carbon sink finally one of the most visible and beautiful designs for urban stormwater management can be found in the heart of downtown Vancouver the new Convention Center green roof green roofs consists of a synthetic growing medium where vegetation is planted depending on the local climate some green roofs are irrigated but typically they don't need to be watered the vegetation takes up much of the rainwater that falls on the roof keeping it from flowing down into the stormwater system the vegetation will filter any water that does seep out so runoff will be of better quality containing fewer sediments and associated metals green roofs are engineered to have many additional benefits in green building design such as temperature regulation in the summer and winter they also provide green space in dense urban areas innovative stormwater management designs come in all shapes and sizes it can be as simple as planting a tree or as complex as an engineered rain garden or green roof using just one of these options on a property can have a significant reduction in stormwater runoff all designs need to be properly maintained and further research needs to be conducted on the longevity of these designs and their effectiveness at improving quality of runoff in our next video we are moving on up see how stormwater is managed at the neighborhood scale when we have roads and traffic to contend with you you