Summerwood

SITUATION

The development of a new residential area brings numerous challenges to the treatment of stormwater runoff. In the planning stage a stormwater management facility has to be designed as a buffer between the completed residential area and the receiving waters downstream. They are also designed to hold excess water to prevent flooding and erosion. In this situation, as in most cases, a storm pond system was implemented which utilizes the biodiversity that develops in these ponds as they mature. During the construction phase however, these ponds are in their early stages. The surrounding ground cover is stripped of vegetation: which would normally guard against erosion by trapping and holding sediment; and the exposed soil is rich with fine particulate matter; adding an even higher sediment load. Lack of vegetation and increased suspended solids cause turbidity problems in the ponds and hinder their development.

At the Summerwood site in Sherwood Park a small creek flows beside the development site to this man-made wetland; it carried large amounts of suspended particulate matter from various areas. In addition to the creek there is a storm drain bringing in water from the streets throughout the development. Strathcona County contacted Clearflow for a solution.

SOLUTION

Besides regular erosion control BMPs such as silt fences; non-toxic, site-specific, polymer blocks were implemented. Clearflow had chemically matched these to soil and water samples collected during a preliminary site visit.

The technology behind the Clearflow’s polymer blocks allow them to self dispense without added energy inputs and only minimal maintenance. The released polymers cause flocculation of the suspended solids, causing rapid settling and water clarification.

To prevent tampering, the polymer blocks were placed in A-frame boxes. These were installed in the stream and weighed down in areas of turbulent flow, essential for the dispensing and mixing of the polymer ensuring optimum performance.

RESULTS

The effect of placing Clearflow’s polymer blocks in the channel was as expected: a decrease in the turbidity of the first storm pond. Instead of a huge sediment plume where the channel entered into the first pond the sediment immediately settled.

The ponds were kept clean throughout the months of construction with a 58% reduction to TSS and Turbidity. This maintained the man made wetlands, making them safe for wildlife in the area.