Over the last several years, the Cape Charles wastewater plant has found itself out of compliance with nutrient loads it dumps in the bay, so much so that the town has had to pay fines to the Department of Environmental Quality for the violations. This last May, the plant once again had a huge spike in phosphorus—the limit is .4, our plant registered a 1.5. From May to July, the plant has been trying to get the phosphorus number under control. Whether the plant will be able to adjust enough to get the year-to-date average below the limit and avoid another fine is still in question.
Town Council met Thursday to get answers from Public Works Director Dave Fauber.
According to Fauber, the major causes of the spike were warmer temperatures and an overtaxed “scum pump”. The temperature theory was dismissed by Councilman Steve Bennett who noted that historical readings in the summer months were superior to the early spring numbers. The scum pump, which is used to process and move waste fluids with high solids content has been operating at maximum capacity, and according to Farber has had trouble getting the job done. The town has rented an additional pump, and is in the process of purchasing two more. The additional, newer pump has been helping to get the phosphorus content down to a manageable number Fauber said.
The town also uses the chemical Alum to mitigate phosphorus and other nutrients in the effluent. Alum has been used for water clarification since the Roman Empire, and is the coagulant of choice for many industrial and sanitary wastewater treatment applications, due to its high efficiency, effectiveness in clarification, and utility as a sludge dewatering agent. Councilman Andy Buchholz questioned how they know how much alum to add and when, “What do you do, just take a sack and dump it in?”
Fauber responded that the plant has a series of valves that release the chemical into the effluent. “But when do you know and how much,” asked Councilman Steve Bennett. “The plant must have some way to get the readings so that it knows how much to release.”
Councilman Buchholz questioned whether the town was testing the effluent enough. Currently, the town tests the effluent twice a month, and sends the samples across the bay to DEQ for analysis. Buchholz suggested that the plant should test once a week just to get a baseline and to stay abreast of when the nutrient load is getting out of range.
Mayor George Proto grilled Fauber on why public works was slow to react. “I’d like to know what you did? When you saw the numbers, what was the plan? We need rules…an action plan for how to address this when this happens again,” Proto said.
Councilman Bennett questioned whether the crew had been properly trained, “This is an expensive, sophisticated plant…it doesn’t appear they have the training to operate it correctly. They need to get the proper training. Three years we have been out of compliance…they need more training.”
Council has tasked Fauber with coming up with an Action Plan in the next weeks.
“I want to see a control plan that will test and take action when something goes off the rails. We need to be able to maintain the plant, not just fix it. We can’t wait until it breaks,” Proto said.
Town Council is scheduled to meet next Thursday to get a progress report from Mr. Fauber.
About the Author
As a water treatment expert, this entire discussion misses the most important issue: Process Capability. There’s no mystery about the chemical process to remove phosphorus from wastewater. https://www.pca.state.mn.us/sites/default/files/wq-wwtp9-02.pdf
Understanding the capability of the process includes:
* functionality of the chemical feed, monitoring and control equipment
* technical understanding of the unit operations (processes) by operators
* operating discipline of the operators, including management and review of operating data and troubleshooting
So when folks try to simply the diagnosis of the problem, consider that it’s really about process capability.
For the record, here’s the chemistry discussion excerpted from the hot link shown above.
Chemical Dose
The required chemical dose is related to the liquid phosphorus concentration. For target concentrations above 2 mg/L (appropriate for chemical addition to a primary clarifier), a dose of 1.0 mole of aluminum or iron per mole of phosphorus is sufficient. For lower phosphorus concentrations in the range of 0.3 – 1.0 mg/L, the dose can be in the range of 1.2 to 4.0 moles aluminum or iron per mole of phosphorus. The pH value is an important factor for efficient removal of phosphorus using alum or other salts, as the solubility of their precipitates vary with pH. Phosphorus removal is most efficient in the pH range of 5
to 7 for alum and of 6.5 to 7.5 for ferric salts since their precipitates will not readily return to solution.
Show me the data. How is this processing spiraling out of control? We probably have no recorded data from which to establish a base line. This is how the ‘big boys’ do it. We spit on the pumps, whack it with hammer and say ‘git er done’. In all seriousness, we are technically overmatched. Virginia Tech is right across the Bay. We need to hire a Mechanical Engineer to oversee this operation. The old boy network is going to lead to a catastrophe. It’s time for The Town Manager to step up and get this fixed or step down and let someone else take over.