Wastewater Treatment Facilities Prepare for Climate Change

Wastewater Treatment Facilities Prepare for Climate Change

Climate change is a growing concern for municipalities and utilities nationwide, particularly those in coastal areas that are most immediately vulnerable to rising sea levels and storm surges. Wastewater facilities and associated pump stations are, by design, located at low elevations and are already experiencing damage from increasing storm intensities. Recognizing the need for long-term planning efforts to protect these systems, the Rhode Island Department of Environmental Management (RIDEM) undertook a project to evaluate the implications climate change could have on the state’s major wastewater infrastructure and identify strategies that would allow to them integrate climate change considerations into wastewater system planning and current operations. 

The work, which Woodard & Curran performed in conjunction with RPS ASA, was recently highlighted in Engineering, INC. Magazine as an example of how private firms are helping municipalities prepare for extreme weather events. We believe that it is critically important that water and wastewater utilities integrate climate concerns into their planning and there are plenty of resources that utilities can use to get started. Here is the methodology that we used to formulate Rhode Island’s adaptive strategies. 

Integrating climate concerns into utility planning

Step 1: Review climate change science and identify potential impacts 
There is a plethora of climate research available, so we began our assessment with a comprehensive literature review to gain a better understanding of how variations in rainfall, air temperature, and storminess will affect the chances of wind damage, flooding, and erosion. Some good sources to include in your review are: Intergovernmental Panel on Climate Change, EPA and NOAA reports.

Step 2: Assess local climate change impacts on infrastructure
Though national sources are very informative, local resources are invaluable in identifying potential infrastructure risks. We drew our local data from two major sources: facility operators and statewide modeling applications. We collected data from the facilities by going over their historical records, administering questionnaires, and visiting facilities. We focused our statewide modeling efforts on four elements:
  1. Shoreline change analysis 
  2. Storm surge modeling with and without sea level rise 
  3. Overland wave modeling of inundated areas
  4. Inland flood zone modeling
The results of the statewide assessments are available for use by the public and are accessible through the STORMTOOLS web GIS and through the Rhode Island Geographic Information System.

Step 3: Prioritize systems for repair
Our study provided each of the WWTFs with a simplified ranking of their systems to prioritize repairs if multiple systems fail at any time. This ranking system will help WWTFs that are predicted to become predominantly inundated under the hazard situations. Here is how we prioritized systems in our study:
  1. Collection and pumping of major flows
  2. Disinfection
  3. Collection and pumping of secondary flows
  4. Primary treatment
  5. Non critical system components: preliminary/secondary/advanced treatment, solids handling
Coincidentally, NEIWPCC published a guide for wastewater managers in September 2016 entitled “Preparing for Extreme Weather at Wastewater Utilities: Strategies and Tips”. This guide is an excellent source for facilities to use to update facility specific emergency management plans.

Step 4: Develop recommendations for adaptive strategies 
Through prioritization and analysis, a clear list of each vulnerable WWTF system should be established. Every system on that list should have an associated adaptive strategy. For this step, it is important to provide estimated cost ranges for system improvements to help with planning and budgeting. Adaptive strategies often fall within one of five categories:
  1. Hardening (e.g., constructing walls and dikes, flood-proofing)
  2. Relocating (e.g., elevating or relocating equipment or systems)
  3. Readily repairable or replaceable (e.g., standardizing equipment or stocking spare parts)
  4. Redundancy (e.g., providing means to convey wastewater to two pump stations or using portable, temporary pumps); or as a last resort
  5. Wet weather bypass (e.g., controlling flow to surface waters to avoid flooding public ways)

Step 5: Educate relevant stakeholders with major findings:
Finally, communicating the information generated is important to help planning and policy development. We prepared customized briefs for each WWTF to summarize the climate change implications to that infrastructure (see table below). The briefs are intended for community leaders to easily understand and communicate the report findings. Also, RIDEM met separately with representatives from each WWTF to review the results of the report as it relates to their facility. 

An easy to read layout of adaptive strategies recommend for a WWTF organized by the systems have the highest priority.

For more information about our process or to learn how your utility can become climate-ready, please contact me at jgreenwood@woodardcurran.com.  

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