September 8, 2022 E.Coli Summary - What You Need To Know
Click HERE to see the slides for the Water Quality / E.Coli Summary Presentation made at the September 12, 2022 Board of Selectmen Meeting
Background
Drinking Water is regulated by the Environmental Protection Agency (EPA) and the Massachusetts Department of Environmental Protection (MassDEP) under the Safe Drinking Water Act. The Town of Wilmington Water Distribution System is constantly tested throughout the month for several contaminants, one of which is Microorganisms. This preliminary test checks for the presence of Total Coliform Bacteria.
Total Coliform is a series of naturally occurring bacteria that is sometimes found in water samples. TC by itself is not all that unusual to find, however protocols dictate that when it is found, the sample is also tested for a sub-set bacteria of total coliform, known as E.Coli Bacteria. E.Coli bacteria is potentially harmful and is typically found in animal waste. A positive Total Coliform result is sometimes an indicator, but not always, of the presence of E.Coli.
Timeline of Known Presence of Ecoli
On Wednesday September 7, 2022, the DPW received routine sample results taken the day before, Tuesday September 6, 2022 from a sampling site at the Hillside Way Water Storage Tank indicating the presence of Total Coliform (TC), but the absence of EColi. Following MassDEP protocols, follow up sampling immediately occurred at the tank itself, a site just upstream of the tank, and a site just downstream of the tank. One of these follow up samples, the upstream sample, indicated the presence of E.Coli bacteria. The Town of Wilmington received this positive EColi result from the MWRA testing lab on Thursday morning, September 8, 2022.
How We Reacted
Following a series of conference calls with MassDEP, the Massachusetts Water Resources Authority (MWRA), and Town Officials, MassDEP informed the town verbally that a Boil Water Order would be forthcoming but it was not official until received in writing. While MassDEP was working on the paperwork for an official order, the town chose to isolate the Hillside Way tank from the rest of the distribution system (in the event this was the source of the contamination) and issue a preemptive Boil Water Advisory to the residents until such time that MassDEP issued the official Boil Water Order to the Town. The Public Buildings Department and the School Department made the necessary adjustments to safeguard the students from using the drinking water system and also discarded lunch foods prepared with cold water. The Health Department began advising restaurants, health care facilities, and nursing homes. When the official Boil Order was received around 2pm on September 8, 2022, the Town revised the advisory notice to an Official Boil Water Order. Both the Advisory and the Official Order were distributed to the town using the Everbridge Townwide calling system (home phone and cell phone), using the DPW website, DPW Twitter, the Town’s main website, the Town Twitter System, the official Town of Wilmington Facebook Page, and social media for WCTV and the Wilmington Apple. An electronic sign board was also posted along Route 62 in the vicinity of Rotary Park and Boston news media picked up the press release as well.
The Days Following September 8, 2022
In order to lift a boil order, two rounds of re-sampling must come back clean. The water distribution system (excluding the isolated Hillside Way Tank) received a clean bill of health on Saturday September 10, 2022 after being re-tested per protocols. MassDEP thus lifted the boil order around 8am on September 10, 2022. It’s worth noting the isolated Hillside Way Tank re-samples still indicated the intermittent presence total coliform during this time. Since the tank was isolated, it did not prevent the Boil Order from being lifted.
Moving Forward
On Monday September 12, 2022, the Town of Wilmington got approval from MassDEP to have a tank inspection contractor come in on Wednesday September 14, 2022 to disinfect and inspect the interior of the Hillside Way tank. This was implemented as planned on Wednesday September 14, 2022 and the tank will be planned for resampling in subsequent days to ensure the Chlorine Residual is back to appropriate levels and that Total Coliform is no longer detected. Once the tank comes back clean, the Town will slowly reintroduce the system water back into the tank before it is officially brought online once again after MassDEP approval.
Tank Post-Chlorination Re-Sample Results
Round 1 Tank sample taken 9/15/22: Results received 9/16/22 indicate NO PRESENCE of Total Coliform.
Round 2 Tank sample taken 9/16/22: Results received 9/17/22 indicate NO PRESENCE of Total Coliform.
DPW will begin re-introducing system water back into the tank on Monday 9/19/22 and will notify tank area residents before the tank is turned back online around mid-week.
Update: Hillside Way Tank will be turned back online Wednesday September 21, 2022 at approximately 10am. Tank area residents may experience stronger than normal chlorine tastes and odors, although this is normal and should dissipate in the upcoming days, if experienced at all.
This concludes the summary updates and additional updates will only be made as needed.