Retention Pond Safety
There are a few different issues with the retention ponds. The first step is to assess the threat that the retention ponds pose. That means developing means by which pollutants can be evaluated. The governmental guidelines will allow for specific amounts of specific pollutants. With the controlled discharges, it is important to know whether or not the discharges are within the mandated guidelines. Thus, the first step is to actually measure what is in those ponds, prior to their discharge. Measuring the contaminants in the sediment is a good place to start, but understanding the amount of pollutants in the water is also important because the water itself will be spilled if there is any flooding.
There is also significant risk should the ponds overflow. The overflow would run across tarmac surfaces and enter the nearby creek without losing any of the contaminants. This issue arises especially when outlets to the creek are open, or if they are open during heavy rain events. There is a higher risk to the public if the creek runs through residential or recreational areas, but there remains a threat to the environment, and ultimately to the company if it is found to be in violation of the laws regarding discharge. The access points by which the pond can flood into the creek should be capable of managing the normal heavy rains for the area, in order to prevent unwanted discharge into the creek. This means that the borders of the pond may need to be raised, such as with a small dyke, above the surface level, to ensure that heavy rains will not cause the retention pond to flood (Jones, Guo, Urbonas & Pittinger, no date).
Diverting rainwater away from the pond might also help.. If at present rainwater is likely to flow into the pond, this increases the risk of flooding that is posed even by normal rainfall events. The creation of channels to divert water is more costly than increasing the depth of the via a dyke, but it would also allow for better control of heavy rains, taking those rains directly to the creek and away from the pond. This will reduce the time it takes the pond to flood, decreasing the likelihood of a flood even occurring.
Another tactic is remedial cleanup of the pond. The land on which the pond sits risks contamination if the sediments or buildup on the bottom of the pond contain toxic materials. These can seep into groundwater, for example, a different form of leak but one that also poses risk to the environment and the public. By cleaning up the pollutants, the pond will have cleaner water, and this will also reduce the risk posed by storms. Bioremediation is often used in oil spill situations, as are chemical remediation techniques. The different remediation techniques are commonly used for in situ pollution situations and can be used to clean up this pond without removing the water, again so that when water is spilled, it contains a much lower level of hydrocarbon pollution than it does today. Oil can be skimmed from the top of the pond, and the sediments can be cleaned via oxygenation that stimulates the self-cleaning potential of petroleum-contaminated anaerobic sediments (Genovese et al., 2014).
Cleaning the pond is something that will need to be done eventually. The pond cannot be allowed to become too contaminated, otherwise the risk will be high. Thus, it is important to have a regular schedule with respect to cleaning up the pond, or at least with respect to testing it. The company should always have a good idea as to what is going into the pond, and therefore a schedule of information should reflect this — managers should always have to report when they put something in the pond. This will help, after the initial cleanup has been done, for the company to keep track of the pond’s chemistry and take periodic remedial actions. The current situation probably arose from neglect and thus taking steps to ensure that there is full control over the composition of the pond can prevent the situation from becoming out of control in the future.
References
Genovese, M., Crisafi, F., Denaro, R., Cappello, S., Russo, D., Calogero, R., Santisi, S., Catalfano, M., Modica, A., Smedile, F., Genovese, L., Golyshin, P., Giuliano, L. & Yakimov, M. (2014). Effective bioremediation strategy for rapid in situ cleanup of anoxic marine sediments in mesocosm oil spill simulation. Frontiers in Microbiology. Retrieved February 24, 2016 from https://www.researchgate.net/profile/Maria_Genovese2/publication/261999189_Effective_bioremediation_strategy_for_rapid_in_situ_cleanup_of_anoxic_marine_sediments_in_mesocosm_oil_spill_simulation/links/00b495395ab712fe04000000.pdf
Jones, J., Guo, J., Urbonas, B. & Pittinger, R. (no date). Safety of detention and retention ponds. University of Colorado at Denver. Retrieved February 24, 2016 from http://www.ucdenver.edu/faculty-staff/jguo/Documents/papers/%28SP6%29SAFETY%20OF%20DETENTION%20AND%20RETENTION%20PONDS.pdf