See How OCSD is Preparing for El Nino

As agencies prepare for the worst in the impending issues caused by El Nino, we asked Nick Arhontes of Orange County Sanitation District how are they are preparing.

What have you found works best when preparing for these kinds of storms?

Communicating with staff, listening to first hand information and observations from prior events, also reviewing data from prior events. OCSD also has the ability to review our Integrated Emergency Response Plan (IERP) which has a specialized High Flow Management Plan for the collection and treatment facilities.

We are able to conduct table top exercises to help staff prepare and work through various scenarios. We also monitor and discuss El Nino information and data from National Oceanic and Atmospheric Administration to understand what is coming and what is expected. Continuing our planned assessments and maintenance of all facilities and all equipment types to identify high risk areas and then expedite repairs and minor improvements if needed. This helps us ensure readiness to provide designed capacity. You never know specifically where the storm cells will be located that can bring the heaviest rains.

Our service area is approximately 470 square miles and we also work with our satellite sewer system partners on a regular basis. We sent out a letter to our satellite partners that also contains some tips for preparation such as applying duct-seal putty to help seal the gap between the manhole cover and frame. We have found that this approach has helped eliminate some of the clear water related inflow in the past.

Our GM also keeps our Board Members updated as they represent the cities and agencies we serve.

Are there other risks associated with high wet weather issues besides “clear water?”

Clear water from surface runoff can bring high peak inflows that could stress the collection and treatment facilities. Illegally connected downspouts and yard drains can also deliver a lot of inflow. Based on prior history, after several days of heavy rain the upper soils saturate and we then see infiltration from private laterals.

Since the sanitary sewer system Waste Discharge Requirements (WDR) Order was enacted in 2002 in our region, many public systems have made improvements due to drivers in the WDR Order and their Sewer System Management Plans (SSMP). We also sent staff out to all channel and creek crossings to see if they noticed non-OCSD facilities that could present risks to us.

We are working with other OCSD staff agency wide and using our High Flow Management Plan to help us prepare. We are usually meeting weekly in order to provide status on high priority preparation items. We also add a few more staff on wet weather standby lists.

What has your agency learned based on past experiences?

Working with our Engineering Department on a routine basis, we’ve made continuous improvements in sewer and pumping and treatment system capacity for many years. Our IERP and its High Flow Management Plan is a useful tool to help us train and prepare.

As needed, it’s also a good time to do some updated flow monitoring so you have current information to plan with, especially if you have a large regional type system that serves numerous satellites like we do. The data is also useful to calibrate our flow model.

And if the storms move elsewhere and we don’t get a lot of rain in our region, which has also happened in the past, we obtain some good dry weather baseline info.

Do you have tips or advice for other agencies on how to prepare?

For collection facilities, review your SSMP (Sewer System Management Plan). Collaborate with and learn from other CWEA and CASA members. Also work with your County and Regional agencies who are also preparing for El Nino. I think that we should also do workshops and post-mortems after El Nino season to share what we learned this time as compared to prior years.


Thanks Nick for the insights!


How is your agency preparing? Or what is your greatest concern about these potential El Nino storms? Tell us in the comments section below…

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Megan Barillo

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