As with any earthcache, there is no “container” to find. Rather, you discover something about the geology of the area or in this case, man made changes that are hoping to fix an environmental issue. The 2016 upgrade of Holland Street and creation of the new plaza space includes numerous innovated design elements to provide improved aesthetics and an engaging space for people.
Holland street is a water smart street!
The sunken garden area within the plaza and the 10 new trees along the eastern side of the road are more than just landscape features. these are Water Sensitive Urban design (WSUD) features known as Rain Gardens.
What is a Rain Garden?
A rain garden is a garden which takes advantage of rainfall and stormwater runoff in its design and plant selection. Rain gardens are sited ideally close to the source of the runoff and serve to slow the stormwater as it travels downhill, giving the stormwater more time to infiltrate the ground via a rain garden.
Rain gardens are usually a small garden which is designed to withstand the extremes of moisture and concentrations of nutrients, particularly Nitrogen and Phosphorus, which are found in stormwater runoff. Most rain gardens drain within 24 hours so there is no worry about attracting mosquitoes that need wet conditions to multiply.
Rain gardens are gaining in popularity in municipalities as a way to beautify a neighbourhood and increase curb appeal by directing rainfall and storm water into rain gardens located along boulevards, municipal parking lots and adjacent to municipal buildings. Rain gardens are also gaining in popularity with home owners as a way to divert rainwater directly out of the storm sewers and use the water to maintain a healthy lawn and garden rather than having to take water from the local drinking supply.
Advantages of Rain gardens:
- Limit the amount of water that enters the local storm drain system.
- Reduce the potential for flooding, drainage problems and stream bank erosion.
- Reduce or eliminate the need to water with municipal water
- Reduce garden maintenance
- Increase garden enjoyment
- Sustainability and urban enhancement
- Reduce the quantity of pollutants that run from our yards and roads straight into our waterways.
- Restore and recharge our groundwater system.
- They are planted with beautiful, hardy plants that require little to no watering.
- Attract birds, butterflies and beneficial insects, such as mosquito-consuming dragonflies.
- Complement any style of landscape and enhance the beauty of the surrounding neighbourhood.
Types of Rain Gardens
Full Infiltration: These rain gardens are used where all inflow is intended to infiltrate into the underlying subsoil. Sources suggest candidate sites have soil permeability greater than 30 mm/hr. An overflow for large events is provided by pipe or swale to the storm drain system.
Full Infiltration with Reservoir: Infiltration gardens with a reservoir have a drain rock reservoir so that surface water can move quickly through the installed growing medium and infiltrate slowly into subsoils from the reservoir below. This type of garden is a candidate for sites with subsoil permeability greater than 15 mm/hr.
Partial Infiltration: These rain gardens are designed so that most water can infiltrate into the underlying soil, while any surplus overflow is drained by perforated pipes that are placed near the top of the drain rock reservoir. This type of garden is suitable for sites with subsoil permeability of greater than 1.0 mm/hr and less than 15 mm/hr.
Partial Infiltration with Flow Restriction: Flow restrictor rain garden variations are used where subsoil permeability is less than 1 mm/hr. The added feature is a flow restrictor assembly with a small orifice which slowly decants the top portion of the reservoir and rain garden. This type of rain garden provides water quality treatment and some infiltration, while acting like a small detention facility.
Benefits of going native!
Native plants are well suited to rain gardens for many reasons. First they have developed a tolerance for the local climate over centuries and require very low maintenance as well as being more hardy and adaptable than most exotic plants. Native plants are more resistive to frost damage, drought and common diseases and herbivores. When mature, native plants form self- sustaining plan communities and since they have long root systems, will hold soil in place and resist erosion.
To log this earthcache:
Rules:
Parking is available close to the rain garden, or park near the Entertainment Centre for easy access.
All observations can be made by walking around the perimeter of the rain garden.
Please send me your answers within 4 days of posting your found log. If there is more than one cacher in your party, include the names in your group. Only one person needs to send me the group answers. No spoiler photo's please. Found logs posted without proof you visited the site will be deleted.
Questions:
1. From your observations of the area, how do you think the rain garden would help to remove pollutants?
2. From your observations, what do you think is the benefit of a small garden rather than a large area?
3. From your observations at the posted coordinates describe in your own words the benefits this rain garden serves at this location?
4. A unique photo of the area with your log is required.
Info: https://www.crd.bc.ca/education/green-stormwater-infrastructure/rain-gardens
https://www.melbournewater.com.au/building-and-works/stormwater-management/options-treating-stormwater/raingardens?fbclid=IwAR0XK14TgyxElVaD0JloS37Q0iU1S0Nc4rWpVxVbvjDh0LC94TV1ScxtAH4