Quick Facts:

The swale is on average just under 1’ deep.

Pre-renovation, the swale was observed to be inundated with up to 2’ of sediment in some areas.

Swale drains to nearby wetlands and eventually to Gilfillan Lake.

Funding:

Project was be funded by the VLAWMO Community Blue grant program and NOHOA.

Reason for Project:

Prior to the renovation, the East Oaks Rec Center Bioswale experienced poor infiltration after rain events. Some areas within the swale have been documented to have poor drainage, while the majority of the swale is inundated with sediment. A renovation was planned to improve the swale’s performance by increasing the swale’s size, introducing a well-draining soil amendment, and constructing new sediment catchment structures (sumps) at the swale inlets.

The Bioswale is an example of green infrastructure that supports North Oaks' stormwater permit and local water resources. The partnership effort helps VLAWMO strive for its goal to capture stormwater close to where it falls rather than increasing the amount that washes off the surface. As the swale temporarily holds water after a rain event, it helps reduce sedimentation and pollution loading to downstream wetlands, lakes, and streams, and replenishes local groundwater.

Construction:

• Excavate clay and excess sediment deposits
• Build two sediment catchment structures at swale inlets, near culverts
• Introduce amended soil with better absorption and drainage
• Lay mulch and re-plant the swale
• Ongoing maintenance to keep catchment structures clear of sediment and debris
• Renovation was completed in August 2021

Results:

The result of the project is improved drainage into groundwater at the East Oaks Rec Center Bioswale, and reducing the risk for the swale exporting nutrients and sediment to downstream wetlands and eventually Gilfillan Lake.

Stormwater runoff treated: 575,192 gallons/year (~14,380 bathtubs)

Total phosphorus (TP) removed from downstream waterbody: 1.44 lbs/year (1 lb TP = 500 lbs algae)

Total suspended solids (TSS) removed from downstream waterbody: 262 lbs/year

Project Image Gallery