Small Parking Lot Rain Garden
Small Parking Lot Rain Garden
Small Parking Lot Rain Garden
Where is this located? As you enter the park, it lies to the right of the park road.
What’s special about this place? The small part of the parking lot is closest to the entry drains to this small engineered rain garden. As runoff slowly makes its way from the inlet to the outlet across the rain garden, plants cause particles to settle and the vegetation and roots take up nutrients and other contaminants. It’s a very effective way to treat polluted runoff in an inexpensive way because the treatment is provided on-site.
About Rain Gardens
A rain garden is a bowl-shaped garden that collects, absorbs, and filters the rainwater that runs off hard surfaces including parking lots, driveways, sidewalks, lawns, and roofs. They provide on-site cleaning of stormwater by using special soil mixtures and low-maintenance plants that soak up runoff. The soil mixes used in rain gardens are selected to allow water to soak in rapidly, treat runoff, and support plant growth. Hardy, often native, plants are carefully selected for each site, including wildflowers, grasses, rushes, ferns, shrubs, and even small trees. These plants can have the added benefit of attracting pollinators, providing habitat for beneficial insects and birds, adding beauty, and improving neighboring property values.
Rain gardens can be small and home-made, or they can be engineered with specific materials to be highly effective. Home-made rain gardens are usually applied in smaller, residential systems working to intercept runoff that would otherwise flow onto streets. Engineered rain gardens are a type of bioretention basin and are sized for specific water quality treatment and flow control capacity that includes designed soil mixes and, often, under-drains and control structures. All the rain gardens highlighted on these tours are engineered bioretention facilities.
Water Quality Benefit: Rain gardens can capture sediment and bacteria, capture oil, pesticides, and fertilizers, and use their mulch layer to bind-up dissolved metals. Plant roots also are host to diverse microbial and fungal populations that filter pollution using biological processes.
Water Quantity Benefit: Special soil mixtures are chosen to allow water to soak into the ground. Roots break up the soil so water can soak into the ground more easily. By absorbing runoff from hard surfaces, rain gardens reduce flooding on neighboring property, reduce erosion in streams, and may recharge local groundwater.
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Native plants are intentionally planted here to infiltrate stormwater and reduce pollution from the parking lot before it enters nearby Squalicum Creek.
Water that doesn't soak in at this rain garden exits the small parking lot rain garden and is directed to Squalicum Creek.
This is where the water enters the rain garden. The rocks on the sides in front of this pipe slow the runoff down – especially during large rain events.
Stormwater flows off the parking lot near the park entrance through a pipe to the rain garden. From the outlet water flows to Squalicum Creek.
This cross section shows the typical components of a rain garden: depression in the ground, special soil mix, mulch layer, overflow feature, and hardy plants.
