When the rains come, certain measures must be taken on construction sites. The San Bruno Project Manager, Zach Steele, explains some reasons and methods behind rainy season-specific procedures.
Weather protection measures are put in place for mainly two reasons. The first reason is to prevent site runoff into the local storm drain system. When sediment or contaminants leave the site they can pollute the local waterways. In order to limit this, many different measures can be put in place.
At San Bruno, we use straw waddle and silt fence around the perimeter of the job site and around spoil piles, as well as DI filter bags in all drains. This helps to filter the contaminants before they have a chance to leave the site. We also run street sweeper trucks to clean the streets if contaminants do leave the site, which is often caused by trucks driving away with mud on the tires.
The second reason to install protection measures is to keep the construction site from eroding. During the rainy season, we want to prevent our site from being over saturated. Covering the site with plastic during the rain allows the water to shed away from the site without being contaminated by sediment and also keeps the water from soaking into the soil and creating muddy or oversaturated condition.
When rain has subsided we can pull back the plastic and begin work again. If a site gets too wet, it will lose compaction. If that happens, workers must wait until it dries out or remove and replace the wet soil which could be very costly.