The straw shooter is purring along, eating up bales of straw and turning them into yellow snow, billowing in the air and blanketing the dirt below. A bitter November wind blows stronger, forcing my chin deeper into the collar of my coat as I wrap my blaze orange vest around me. “Argh, argh, argh,” calls the wind; Tim the Toolman would approve.
After several years of rest, the development boom in Washington County is starting up again. Earth is moving, and new homes are springing up in Stillwater, Woodbury, Cottage Grove and other growing communities. Visiting one of these active construction sites can be an over-stimulating experience. Enormous machines are racing around much faster than it seems like they should be able to move and the noise, noise, noise would drive the Grinch crazy. There’s booming and rattling, beeping trucks backing up, diggers digging, and front-end loaders moving dirt from one pile to another. Despite the apparent chaos, however, these sites aren’t quite the Wild West they used to be.
The Minnesota Pollution Control Agency has had a Construction Stormwater Permit since 2003. This permit, which was revised and reissued on Aug. 1, 2013, requires all construction activity that disturbs 1 acre or more of soil to include stormwater management practices and erosion and sediment control techniques that keep dirt and dirty water out of nearby wetlands, lakes and streams. Watershed districts and cities often have additional requirements to protect sensitive surface and groundwater resources. Without protections like these, the U.S. Environmental Protection Agency (EPA) estimates that the typical construction site loses 20 to 150 tons of soil per acre to stormwater runoff each year.
Silt fence is probably the most ubiquitous and easily recognizable sediment control material. Made from long swaths of black fabric, these temporary fences are erected around the perimeters of construction sites to hold back mud and dirty water that would otherwise flow directly into nearby wetlands and ponds or storm sewer systems. Though relatively effective when used correctly, they are often installed poorly and maintained poorly and are by no means capable of stopping water pollution on their own.
During a recent field seminar hosted by the South Washington Watershed District, East Metro Water Resource Education Program, and Minnesota Erosion Control Association vendors demonstrated how to use an astounding array of erosion and sediment control materials other than silt fences. There are wood, straw and coconut fiber mats that can be placed on bare soil to keep the dirt from washing away, and compost mixes that help grass seed to grow more quickly. Sediment control logs that look like giant nylons can be filled with recycled wood chips, rock or natural mulch and laid out around the perimeter of job sites to keep dirt from washing into roads and waterways. Inlet protection devices are placed on top of or inside storm sewer grates to keep dirty water from flowing into the pipes while construction is under way, and giant white mats can be laid out at entrances and exits to capture dirt from trucks.
Best of all are the straw shooters, hydro-seed and hydro-mulch machines that can cover acres of bare soil with straw, seed or mulch in a matter of minutes. What’s not to love about a giant vacuum cleaner operating in reverse? “Argh, argh, argh.”
With the new construction stormwater permit now in place in Minnesota, the effort is under way to ensure that everyone involved in construction projects, from builders and developers, to contractors and subcontractors, is following the rules and understands how to correctly use and maintain erosion control materials on their sites.
If you see a construction site with failing or inadequate erosion control protections, contact the city or your local watershed district or file a complaint with the Minnesota Pollution Control Agency at 651-296-6300 or pca.state.mn.us/index.php/about-mpca/assistance/citizen-complaints.html.
To learn more about the MN Program for Construction Activity, go to: pca.state.mn.us/index.php/water/water-types-and-programs/stormwater/construction-stormwater/index.html.
Angie Hong is an educator for East Metro Water. For more information go to mnwcd.org/cleanwater or contact Hong at [email protected] or 651-275-1136 ext. 35.