Mar 11, 2013

Lay It Down

Pavement for hospital lot needed to withstand tough Canadian winters, heavy usage

The expansion of the Peter Lougheed Hospital required new pavement surfaces for its roadways for ambulance use and the parking lot.

Since the city of Calgary, Alberta, Canada, has developed a storm water management strategy to protect watershed health as the city continues to grow, the hospital was asked to utilize techniques and materials that have a positive impact on the environment.

The owners, Calgary Health Region, decided to use SF-Rima permeable pavements, which eliminate storm water runoff. The water or snowmelt infiltrates through open joints and filters through various aggregate layers, removing up to 95% of the average annual post-development total suspended solids and up to 70% of the average annual post-development total phosphorous, based on the average annual loadings from all storms less than or equal to the two-year/24-hour-storm. The water then is allowed to return into the local groundwater system.

The Calgary climate experiences Chinook conditions throughout the winter. Warm temperatures allow snow to melt and permeate between the joints to the sub-base, therefore avoiding water from pooling and freezing when temperatures drop.

The water enters the pavement through the open joints between SF-Rima paving stones and drains in to the underlying open graded layers. It is not retained in the pavement's surface structure and thus demonstrates good freeze-thaw resistance.

Water ideally drains to the subgrade layer relatively quickly without freezing in place.

The coldest temperature is near the pavement surface. Freezing gradually progresses into the base layers and subgrade where the frost remains for only a short time.

Regular snow removal equipment is being used to remove the snow, but not sand or deicing material, to avoid clogging of the joints and to avoid pollution. Instead, gravel material, the same aggregate used in the joints, should be chosen to provide traction.

Reduction or elimination of storm water runoff helped to achieve LEED credits for water management.

The SF-Rima paving stones for this project used the new Kolorscapes process, which places the color in the top 10% of the paving stone. This process also allowed for white cement to be used to achieve the Solar Reflective Index rating.

The permeable pavement provided the hospital with a durable surface that is attractive, low in maintenance and functional.

Permeable pavements can reduce or even eliminate costly storm sewer systems, reduce the size of storm water detention ponds and provide additional land area for potential development.