Troubleshooting

The three most common issues with existing FWS constructed wetlands are (1) short-circuiting, (2) lack of ammonia reduction, and (3) mosquitoes. Short-circuiting can be evaluated using dye or tracer testing or by aerial photography. An example of a lithium chloride tracer study at Sacramento County is shown in Figure 6.6. Baffles, earthen berms, and open-water zones placed perpendicular to the flow path can be used to overcome identified short-circuiting conditions (Crites and Tchobanoglous, 1998). Ammonia removal improvements usually can be attained by adding a nitrification filter bed (NFB), as described in Chapter 7. See Section 6.10 for a description of mosquito control techniques (Andrews, 1996).

FIGURE 6.6 Tracer study at free water surface (FWS) constructed wetlands in Sacramento County, California.

Time (days)

FIGURE 6.6 Tracer study at free water surface (FWS) constructed wetlands in Sacramento County, California.

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