Waterwise Wednesday: Trees Tame Stormwater

Trees play a critical role in managing our city’s stormwater runoff. Enjoy this interactive poster from the Arbor Day Foundation highlighting the role trees play in urban stormwater management.


Waterwise Wednesday: What a drip!

Drip and emitter systems conserve water by regulating volume, velocity, and direction of water flow. Plants can be targeted with a slow steady specific quantity of water using drip tubes or emitters. This prevents over watering and watering where not needed. And the systems are discreet, designed to function effectively while lying under a layer of mulch.

Construction Bulletin April 2014

Goals for Construction Site Runoff Management

Ahh, Spring— warmer weather, thawing ground, and afternoon rain showers.   While welcoming the change of season,  it’s also time to consider Best Management Practices (BMPs) for keeping the soil on site and preventing stormwater run off and sediment pollution.

The ultimate goal for construction site runoff management is to prevent the pollution of stormwater runoff.  Best Management Practices (BMPs) aim to slow the velocity, control the volume, and/or  filter  site run– off.  Stormwater permits require BMPs to address erosion and sediment run-off, soil exposure, ground disturbance, compaction,  buffers,  outlet protection, and stabilization.  Below are some BMPs to consider for construction sites.


Stabilization, or planting ground cover,  allows run off to infiltrate the ground providing nutrients to the plants and replenishing ground water. Stabilization is required by the Nebraska general construction permit as soon as practicable on sites and no more than 14 days after construction activities have ceased.


Slope Drain

When the slope is steep channeling the runoff through a slope drain can be an effective erosion control.  Drains may be made of pipe,  s shown, or a constructed channel lined with rock,  turf replacement mats,  and wattles to slow the flow of water.


Flexible Gutter

Flexible rain gutters can direct roof water away from exposed soil.  The gutters can channel water to impermeable areas (e.g. concrete driveways) where clean stormwater can run to the gutter or to vegetated areas where plants and soil can absorb the water

InspectionRegular inspection,  every 14 days and within 24 hours of a 1/2” rain event,  is the best way to insure construction site BMPs are working effectively.  Look for evidence, or  potential,  of pollutants entering the drainage system.  An inspection report must be identify any incidents of non-compliance with permit conditions and actions taken to correct the issue.  If no incidents of non-compliance were found, the report must contain a certification that the site is in compliance with the Storm Water Pollution Prevention Plan (SWPPP). The  reports should be retained with the SWPPP for up to three years after the permit expires or is terminated.



Construction BMPs: Temporary Stabilization

This straw mulch has been crimped into the ground for temporary stabilization.

Stabilization, or establishing ground cover to protect disturbed soils from erosion, is not only a good practice, it is required by law.  The Nebraska state Construction General Permit states that, with a few exceptions such as snow cover or frozen ground conditions, “stabilization measures  must be initiated as soon as practicable in portions of the site where construction activities have temporarily or permanently ceased, but in no case more than 14 days after the construction activity in that portion of the site has temporarily or permanently ceased.” Since it is unlikely that suitable vegetation can be established within 14 days, other methods of stabilization must be considered.  Covering exposed or disturbed areas protects the soil from raindrop impact, slows the flow of and infiltrates stormwater, and protects newly seeded areas.  It also helps retain soil moisture, which will help your vegetation become established more quickly.

One of the simplest methods of erosion control is mulching.  Straw or hay mulch should be applied at a rate of 2-3 tons per acre.  To provide good ground cover, at least 50% of the mulch should be ten inches in length or longer.  The mulch should be crimped using a weighted roller that anchors the mulch into the soil.  If the area is seeded before the mulch is applied, this can be a very simple and effective method of preventing erosion while vegetation is established.

Another method of erosion control is a rolled erosion control blanket.  These can be made from natural or synthetic materials and can be effective in protecting steeper slopes from erosion.  They are designed to be rolled onto the area and stapled into place.  Always follow installation specifications, as poor installation can cause these products to fail. 

This erosion contol blanket temporarily stabilizes the slope while vegetation is established.

If the blanket is not properly anchored and stapled, it can either be washed away or stormwater can wash out soil underneath the blanket, causing small gullies that are difficult to seed.  If the area is seeded and the erosion control blanket is installed correctly, grass will grow up through the blanket, and over time, the blanket will degrade.

For extremely steep slopes or areas with limited access, hydraulic mulching should be considered.  In this process, a slurry made up of mulch, seed, and a tackifying agent is sprayed onto the disturbed area.  There are also many other products and stabilization methods available.  Each site should be carefully evaluated to determine which product or combination of products is the most effective and economical way to achieve stabilization.