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Current Research

Check Dam Design for Maximum Effectiveness and Polyacrylamide Dosing

This involves testing the effectiveness of different check dams for sediment capture and release of PAM to flocculate runoff.  Some of the dams we are testing include standard rock, rock covered with erosion control blankets, and coir wattles.

 

Advanced Best Management Practices for Maximum Erosion, Sediment, and Turbidity Control

We have developed and tested a number of approaches to reducing sediment in construction site runoff and are deploying these on construction sites to determine how well they work.  Active construction sites are particularly challenging because of the constant changes as grading and building progresses, so this “real world” project will provide guidance on the best approaches to successful designs and installations.

 

Evaluation of Ground Covers on Construction Sites

There are a wide variety of products used as ground covers, including blown materials (mostly straw), hydraulically applied fibers, and erosion control blankets.  In addition, applying polyacrylamide along with these ground covers has great potential for further erosion reduction.  We have a continuous program of  evaluating this for both erosion reduction and vegetation establishment. 



Channel Lining for Erosion Control

When construction site stormwater is collected into temporary channels, some form of lining is needed to prevent erosion in them. We are testing several options to achieve channel stabilization: jute netting, jute netting with polyacrylamide applied underneath, excelsior blankets, and a spray-on concrete product. Tests are being conducted both under controlled conditions (a simulated channel) and in the field on active construction site

Example of erosion in the unlined test ditch.
Example of erosion in the unlined test ditch.

Field testing of a spray-on concrete product for its potential in stabilizing temporary ditches.
Field testing of a spray-on concrete product for its potential in stabilizing temporary ditches.



Alternative Methods for Dosing Construction Site Stormwater with Polyacrylamide

Applying polyacrylamide (PAM) powder to fiber check dams is a well-proven method of reducing turbidity in construction site stormwater. We are also exploring alternative methods which may provide more control over the dosing process. Two examples are shown below, one using a simple float valve system and a weir, and the other is a rain-driven system developed in New Zealand. Both involve dissolved PAM, which is good because it reacts quickly with the suspended solids. The drawbacks are that the solutions can freeze and have to be replenished after each storm. We are interested in determining if the benefits are worth the effort

A float valve is positioned behind the square-notch weir and releases PAM solution in proportion to the height of the pool behind the weir.
A float valve is positioned behind the square-notch weir and releases PAM solution in proportion to the height of the pool behind the weir.

With the rain-driven dosing system, the rain is collected on the roof and directed to a tank floating in a larger tank filled with PAM solution.  As the rain water accumulates in the floating tank, it sinks, displacing the PAM solution into a hose that discharges into the ditch.  As a result, dosing is proportional to rainfall.
With the rain-driven dosing system, the rain is collected on the roof and directed to a tank floating in a larger tank filled with PAM solution. As the rain water accumulates in the floating tank, it sinks, displacing the PAM solution into a hose that discharges into the ditch. As a result, dosing is proportional to rainfall.



Methods for Remediating Compacted Post-Construction Soils to Improve Infiltration

The process of building roads and structures usually results in a surface soil composed of compacted subsoil material. We are exploring tillage and amendments to improve the soil for both infiltration and vegetative growth. Key questions are: how long does the “tillage effect” lasts, how do amendments affect infiltration and grass growth, and how resilient are these soils when mower traffic is added.

Test plots being established on a compacted subsoil.
Test plots being established on a compacted subsoil.

 

 

 
 
 
 


Image of road ditch lined with coir wattles used to reduce to velocity of water.


Image of basin with baffles and slope drains used as protected entrance devices.


Continuation of basin above showing baffles installed as well as skimmer as drain down device.


Evaulation of various types of erosion control blankets, mulches, and hydraulically applied fibers.

 

 

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