The Columbia South Shore Well Field in Northeast Portland is intended as a backup water supply system for the city of Portland, but city auditors and outside consultants have found it faces several challenges, specifically in the areas of earthquake resiliency and the presence of a naturally occurring mineral that affects the quality of the water at high levels.
The main source of Portland’s drinking water comes from the Bull Run Watershed about 26 miles east of the city. The groundwater system at the well field is often used during the summer to supplement that water, and it is also used during times of increased turbidity of Bull Run water, usually during storms.
As it stands right now, the groundwater system will likely be severely damaged in a major earthquake, like the 9.0 magnitude shaker that is predicted to occur anytime along the Cascadia Subduction Zone off the coast.
But earthquakes are not the only threats to the well field. The mineral manganese is present in some of the aquifers the wells draw from. While manganese is not harmful to humans at low levels, this winter the Portland Water Bureau decided that the issue is its highest priority for the groundwater system.
The water bureau says the Columbia South Shore Well Field could potentially be used as a backup water source if Bull Run water is unavailable -- like after a massive earthquake.
But in a 2017 “Water System Seismic Study” conducted for the water bureau by InfraTerra, a San Francisco-based consulting firm that specializes in geologic and seismic hazards, it was found that during an earthquake the well field is at risk for liquefaction -- a process where extreme shaking essentially turns soil into liquid -- and at least half of the 27 wells that pump water out of the ground will fail.
Consultants found those failures will cut the potential flow of water from the groundwater system about in half, from 80 million to 95 million gallons of drinking water a day to 45 million gallons a day.
On average, nearly one million Portland Water Bureau customers use 122 million gallons a day during the summer, and 85 million gallons a day during the winter.
It is estimated the city will need to spend about $200 million to harden the well field against earthquakes, the consultants reported.
Through a public records request, KATU asked for the entire report from InfraTerra, a 2017 inspection report of the Bull Run dams, as well as other documents. The city denied public access to the inspection report of the dams and only supplied the executive summary of the report from the consultants. It argued that what it kept from the public was exempt from disclosure because of security reasons under federal law. KATU appealed to the Multnomah County District Attorney’s Office, but that office sided with the city.
Earthquakes Not The Only Issue
Manganese, a naturally occurring mineral, is not considered a health hazard to humans at low levels, but it can make the water taste and smell bad. The Environmental Protection Agency has set what it calls a Secondary Maximum Containment Level of 0.05 mg/L for manganese in public drinking water. Any levels above that and the water can become discolored and affect its aesthetic quality.
Portland’s groundwater system draws water from three aquifers in Northeast Portland along the Columbia River: Blue Lake, Troutdale Sandstone, and Sand and Gravel. Three high-producing wells in the Blue Lake aquifer are the ones being infiltrated with manganese, according to city auditors.
The bureau says the levels in the Blue Lake aquifer range from nondetectable to 1.2 mg/L, depending on location. But, it says, the wells in the aquifer it uses for drinking water have levels below .005 mg/L.
According to the bureau, it has seen changes in levels of manganese in these wells in the last few years. It says because of that, and the fact they are occurring in high-producing wells, it has placed addressing the manganese levels as its highest priority for the groundwater system.
The bureau says it is working to better understand the presence of manganese in the aquifers and says there are two options to deal with it. One, manage it through hydraulic means and two, treat the water to reduce the manganese.
Right now, the bureau is managing the manganese through a “hydraulic management strategy.”
Doug Wise, groundwater protection program manager for the Portland Water Bureau, described that strategy as pumping water between zones of higher and lower manganese.
“It’s a little bit of a yo-yo approach,” he said during an interview. “When we’re operating, we know that we’re going to be pulling some manganese water towards our wells, so we reverse that yo-yo when we’re done with the supply production and tee ourselves up for a new supply run.”
He says the bureau has updated its hydraulic model “so that we can refine our understanding of where that manganese is and how it’s moving, so we can tailor a longer-term solution which may simply be to carry forward what we’re doing with hydraulic control.”
He added that the bureau needs to invest in studying the issue more to develop a long-term plan.
In a June 2020 audit of the groundwater system, city auditors suggested there was a tug-of-war of priorities because of limited resources and found the water bureau could do more to come up with a plan to balance competing priorities.
“For example, if the Bureau determines it should build a plant to address manganese contamination, how might that interfere with plans to make the system more seismically prepared?” they wrote.
Because of the $200 million price tag, city auditors wrote seismically hardening the groundwater system was considered “medium priority.” The water bureau’s top priority is to make the conduits that transfer water from Bull Run to the city earthquake resistant, auditors said.
The water bureau cast the issue within the context of short- and long-term planning and as part of what it calls its “adaptive planning approach.”
“At this time, the risks due to manganese in the Blue Lake Aquifer (BLA) are not a driver for a major project,” the bureau’s Chief Engineer Jodie Inman wrote in response to emailed questions. “The Water Bureau is managing manganese in the BLA by adapting our near-term solutions and considering how and when they would be included in the capital plan.”
Inman added that because of the bureau’s proactive planning, “If manganese treatment is needed, it can be incorporated with other longer-term seismic resilience goals.”
In a follow-up email, Wise said the water bureau does not currently need and does not currently plan to build a manganese treatment plant.
If the bureau did decide to build a plant to treat manganese, the cost to do so would be determined through the city’s normal planning process, City Council approval, research, and bids from contractors, he said.
“The scope of the project and market at the time that facility would be built would affect the cost,” he said.
Preparing/Upgrading for Earthquakes
In the event of a major earthquake, which would likely result in the water system being knocked offline, Wise stressed that people need to be prepared.
“The single most important thing that your readers or viewers need to know about the Cascadia Subduction Zone is that all of us individually need to have our own supply of emergency water,” he said in an interview. “That’s a gallon per person or pet per day in your household for a minimum of two weeks.”
City auditors noted that the water bureau had developed a plan on specific actions it would take right after a major earthquake to stabilize the water system.
That plan is presumably found in the 2019 Backbone Isolation Plan. The city denied the public access to that document as part of KATU’s records request, and the DA’s Office agreed with the city on appeal.
In an email, the bureau described what it said the plan included.
“Immediately following an earthquake, our focus is on preserving available supply in key reservoirs, isolating critical transmission mains, and reducing leaking of water from our pipelines. After the initial responses, we evaluate available supply resources through field inspections to develop priorities for water supply, distribution and treatment,” the bureau said.
While the bureau did not provide information on specific projects it was undertaking or planning to shore up the groundwater system, Wise said seismic resiliency is part of its capital planning over the next five to 10 years.
“Seismic resilience is now built into every Water Bureau project,” the bureau said in an email. It listed off several projects including the Washington Park Reservoir Improvement Project, Willamette River Crossing, the Bull Run Filtration Facility and pipelines, as well as smaller pipe projects to install earthquake resistant pipes.
The bureau is also working to implement its Seismic Implementation Plan. The executive summary, obtained through a public records request, can be viewed here.
In 2013, the Oregon Legislature set in motion the Oregon Resilience Plan, which set as a target of 2063 to get the state ready for a big Cascadia Subduction Zone earthquake. The Portland Water Bureau has said it is working within that plan to shore up its backbone, so the water system is functional within 24 hours of a major earthquake. Additionally, it has said it is working to replace distribution pipes so it can repair failures within two weeks.
“While folks are safely subsisting on their household emergency water supply, we will be out there from the get-go assessing the damage to the system and prioritizing repairs to maximize the benefits to the public and get the public supply system back online as quickly as possible,” Wise said.
Audit Recommendations
In the June 2020 audit of the groundwater system, city auditors recommended the Portland Water Bureau clarify its organizational structure around the groundwater system, document all the needs of the system, and create a long-term plan to “prioritize actions within limited resources.”
Two years later in a follow-up report, auditors said the Water Bureau had not yet completed those recommendations, with bureau officials citing the COVID-19 pandemic as the main cause for the delay.
Wise said during an interview a charter document is drafted and will be implemented this fall.
He said his team presented their final recommendations of the program’s strategic business planning process in January and is presenting those recommendations to the bureau’s Groundwater Steering Committee.
“They include items that address the auditor’s recommendations, most substantially better communications of the progress we are making in the groundwater system through an annual report from the Groundwater Steering Committee that will detail the progress we’ve made over the last year, and what we say is the risks going forward,” he said.
Corrections: A previous version of this story incorrectly stated the water bureau is studying the infiltration of manganese and that it was seeping into the aquifers. Manganese is always present, and the bureau is studying its natural occurrence in the aquifers. Also, the well field is in Northeast Portland, not North Portland as was previously written.
Sidebar: Other Issues/Water Bureau Responses
Auditors noted that a group of chemicals known as PFAS is “an emerging contaminant.” They said they have been found in or near the Columbia South Shore Well Field.
Separately, the water bureau says consultants with Cornforth Consultants found the two dams at the Bull Run reservoir would likely withstand a large earthquake. The consultants with InfraTerra did not include the dams in their study but found the three conduits that transfer the water from the dams to the city are at risk for landslides and liquefaction.
Below, are responses from the water bureau on both those items.
We didn’t get a chance to touch on the PFAS issue during the interview. Can you give me an overview of what is happening there and what the water bureau is doing to combat the infiltration of these chemicals into the groundwater? Where is it on the priority list? How much will it cost to deal with the issue?
Everyone plays a role in helping to protect public health and the environment from degradation. The EPA has information specific to PFAS and steps people can take to reduce their risk from this class of chemicals at https://www.epa.gov/pfas/meaningful-and-achievable-steps-you-can-take-reduce-your-risk.
We have not detected PFAS in any of our active supply wells. The Water Bureau is monitoring our groundwater resources, tracking the science, and following the development of regulations to guide our actions. There are no known manufacturers of PFAS in or near the Columbia South Shore Well Field. There are a few local sites known to have been impacted by PFAS-containing firefighting foams in the past. Current monitoring suggests that there is no immediate risk to Portland’s water supply wells from these sites.
Portland has a Groundwater Protection Program dedicated to preventing contamination impacts to our water supply sources. PWB has local regulations on hazardous substances in the Columbia South Shore Well Field, including roughly 175 individual PFAS compounds. The protection program requires businesses in the well field to report their hazardous substance inventories to the bureau annually and includes bi-annual inspections of well field businesses in collaboration with Portland Fire & Rescue. The Water Bureau also collaborates with the Oregon Department of Environmental Quality to accelerate contaminated site discovery & cleanup in the wellhead protection area. There is information for the general public and the businesses that are regulated by the program on the City’s website at http://www.portlandoregon.gov/water/29890.
How much PFAS has been found in the aquifers and which ones?
Portland monitors for hundreds of different substances, including common ions, nutrients, bacteria, metals, and organic compounds. Groundwater quality is monitored in the aquifers at monitoring wells, at individual drinking water production wells, and at the outlet of the Groundwater Pump Station where groundwater blended from individual wells enters the distribution system. We have not detected PFAS in any of our active supply wells or from the blended groundwater entering the distribution system. Monitoring has found some low levels of PFAS in monitoring wells in some areas of relatively shallow groundwater that are not currently used for public water supply.
Bull Run question: What has been done so far to seismic retrofit/replace sections of or all of the 3 conduits from Bull Run that were identified by consultants in 2017 as likely to be damaged by landslides and/or liquefaction? At what cost?
As mentioned above, improvements to the conduits and the system are part of the long-term Seismic Implementation Plan (SIP) with a current horizon of 2045.
There are multiple efforts underway related to conduit to seismic improvements. The first is the Conduit Least Hazardous Route Planning report, which further developed the long-term plan for conduit improvements as the next step in the SIP related to the conduit backbone. This included geotechnical field work needed before design can begin. A contractor has been chosen for the field work and we are completing a contract with a consultant with a value of $980,000.
In addition, significant work to establish seismic standards for the conduits is being done as part of the Bull Run Pipelines project, which will also install approximately 35,000 feet of seismically resilient conduits.
Other work on the conduits, including repairs and seismic improvements, are in the early design stages. This is a challenging time for large steel pipe replacement with the very high material costs and supply chain issues. The bureau is doing some construction, and also using these early years to understand the geology, risks, and challenges that will go into these projects to better inform appropriate resourcing of staff and capital improvement funding.