Controlling Post-Construction Erosion.

In many cases, once a construction site has reached final grade and the building process has largely been completed, establishing vegetation on the landscape is the final step.  When the area is seeded, a ground cover is needed to provide temporary erosion control and to protect the seed and create a good germination environment.  There are many options for ground covers, including straw, erosion control blankets (ECBs), and hydromulch.  Over more than 10 years, we have been testing these for their ability to control erosion and to produce healthy stands of grass.  In addition, we have tested the addition of polyacrylamide (PAM) to augment ground covers to further reduce erosion and improve runoff water quality.  Tests have been done under simulated rainfall conditions and on construction sites.  Straw is the least expensive material and the most commonly used, so we always included that for comparison to other materials.  In general, straw with PAM reduced erosion as well as the better hydromulches.  Adding the PAM in granular form can result in higher erosion in very heavy rainfall events such as we tested in our simulator, and more PAM is lost compared to when it is applied in dissolved form.  Hydromulches and ECBs did not provide for better grass growth than straw under field conditions.  The most reliable predictor of successful grass establishment was the weather pattern after planting, particularly the rainfall amount and timing.