Leaks beneath stations responsible for New Orleans drinking water went undetected for two years
One of the three Sewerage and Water Board pump stations responsible for the east bank's drinking water had leaks that went uninvestigated for two years.
Leaks from beneath one of three Sewerage and Water Board pump stations that distribute the majority of New Orleanians’ drinking water went uninvestigated by the Board for nearly two years.
The drinking water leaks were discovered during major upgrades to the Claiborne Avenue Pumping Station on the northern edge of the Carrollton Water and Power Plant in 2021. Based on contemporaneous correspondence and archival drawings released by the Board, the leaks’ source is most likely an unpressurized reservoir beneath the station, raising concerns about the safety of the city’s drinking water.
The Louisiana Department of Health confirmed Tuesday they had not been informed of the leaks until contacted by The Lens.
The Sewerage and Water Board has acknowledged the presence of chlorinated water, indicating treated water is leaking, but officials maintain they know of no leaks in the wall of the reservoir, known as a clearwell. They made no such assurances about the floor of the clearwell.
The Louisiana Department of Health, which enforces statewide drinking water regulations, is looking into the matter and has “requested information about the operation and inspection of the clearwell,” according to a spokesman, who also said the agency had not been informed of the situation prior to The Lens’ questions.
Water board staff confirmed the presence of chlorinated water three months after the leaks were discovered by contractors in 2021 and authorized short pieces of sheet piling to be driven to slow the flow of water during the construction — but did not perform any repairs to the leaks themselves.
The lack of investigation or repairs, combined with the high groundwater table surrounding the station and the design of the station itself appear to have increased the risk of contamination from bacteria and other contaminants of the entire east bank water supply, according to documents reviewed by The Lens.
The leaks were exposed during excavations on the north side of the station which have since been filled and restored.
Board officials reached this week said that prior attempts to inspect the reservoir had proved futile due to the high velocity of water flowing through it. Additionally, the Board said the operational configuration and the original construction of the reservoirs – there is more than one at the Carrollton Plant – “do not allow them to be isolated, shut down, or emptied,” but that they may investigate using a Remote Operated Vehicle, or “ROV,” a remotely piloted submarine widely used in the offshore industry.
H.J. Bosworth, a professional engineer with experience in water systems said the conditions are concerning.
“The S&WB’s Claiborne treatment plant is clearly an old facility with issues that date back dozens of years,” he wrote in an email to The Lens after reviewing several documents.
Water can seep through concrete, the material the clearwell is made of, when there are differences in water pressure on either side of the material, Bosworth said.
“Gravity flow of millions of gallons per day to the pump houses takes place with the water levels in these buildings that are below the level of the nearby ground. Periods of heavy rains is expected to elevate the ground water levels above the operating level of the drinking water. This equates to greater pressure from the groundwater than the pressure of the drinking water in the open basins in the pump houses. This pressure is expected to potentially contaminate the drinking water after heavy rains.”
Leaks identified April 2021, payment disputes extend over a year
In April 2021, contractors with construction company M.R. Pittman identified multiple leaks from the clearwell while working at the Claiborne Avenue Pumping Station on the north side of the Carrollton Water and Power Plant. The Carrollton plant supplies drinking water to the entire east bank of New Orleans, while the west bank has a separate water treatment plant. The agency disputes the clearwell was the source of the leaks, but did not identify an alternate source when asked
The workers diverted the leaking water — which in August 2021 was confirmed by the Board to contain chlorine indicating it had been treated for drinking — away from the construction site to allow the building of concrete vaults for new automatic pump flow meters. The work was part of a $38 million FEMA-funded contract to rehabilitate the pump station, the second largest public works contract in Board history, behind only the $40 million effort to build two water towers at the same site.
While the Board rapidly approved Pittman’s “time and materials” efforts to mitigate the leaks’ effects and pump away the drinking water during construction, the agency went back and forth over payment for over a year. The dispute centered over whether Pittman’s work to divert the leaking drinking water was considered part of their original contract or was “extra work” and thus deserving of a change order.
At their June 2022 meeting, the Sewerage and Water Board of Directors granted Pittman’s request for a change order and authorized payment of $53,238.33 without discussion of a public summary of the work included in their meeting packet. At the meeting, Interim General Superintendent Ron Spooner described the extra work only as “water leak mitigation that the contractor is encountering.” A comprehensive review of contracting and budget documents on the Board’s website reveals no additional action taken by the Board or its contractors to fully investigate or address the leaks since their April, 2021 discovery.
The dispute generated numerous documents detailing the leaks and the surrounding conditions. Those documents, obtained by public records requests by The Lens, when combined with others released by the Board provide a broader picture of risk to the drinking water supply.
Leaks from underneath Claiborne pump station
According to agency documents, leaks were found in the bottom slab of the clearwell, a reinforced concrete covered channel running beneath the entire Claiborne pumping station with its base 15 feet below ground level. The phrase “clearwell leaking” appears 19 times in the change order document package, including as the order’s title on the first page.
The channel stores unpressurized drinking water which flows from the adjacent treatment system by gravity, evening out changes in upstream flow rates. Four pumps are mounted above the clearwell, drawing up drinking water from the channel and pushing it out to the city’s taps at approximately 70 pounds per square inch (psi).
The entire clearwell was constructed below ground level when the station was built in the early 1960’s, a design identical to the clearwells at the other two pump stations at the Carrollton Plant – known as Panola and High Lift – built 30 to 40 years earlier. Current state drinking water regulations forbid such construction without ensuring at least 50% of the drinking water depth within the clearwell is above ground level, and also require such structures be secure from groundwater. It is unclear whether such regulations were in effect at the time the Claiborne pump station was built. The state department of health said this week it was unaware of ever granting the Board regulatory exemptions to those rules.
Based on operational logs and station drawings released by the Board, the maximum pressure at the bottom of the well – pressure resulting only from the weight of about 10 feet water – constantly runs at approximately 4 psi. At the same time, the elevation of the top of the drinking water within the clearwell is about 5 feet below ground level, or 10 feet below what the current health regulations require.
But the agency said those levels are unknown.
“The relative elevations of the clearwell operating level and groundwater have not been determined,” Birch wrote in an email. “SWBNO has no evidence that there is contamination in the clearwell due to groundwater infiltration. SWBNO regularly tests drinking water at sites throughout the city and has found no evidence of contamination.”
However, according to a document generated by contractor Stanley Consultants during the Board’s change order dispute with Pittman, 5 feet below ground level is also the elevation of the groundwater table just outside the station expected during Pittman’s construction. The combination of low pressure within the well, equal groundwater elevations outside the well, and likely cracks in the well’s slab appears to provide a hydraulic path for contamination of the drinking water supply in the Claiborne pump station. And since all three clearwells at the Carrollton Plant are joined by underground piping and conduits, such contamination could extend to any water pumped from the plant, not just from the Claiborne station.
The Board is not unfamiliar with the elevated groundwater table at the Carrollton plant. In 2019, during renewal of their state surface water discharge permit, they told the Louisiana Department of Environmental Quality (LDEQ) that numerous hoses draped from inside the powerhouse to a nearby manhole – visible in Google Streetview photos of the 8700 block of Spruce Street dating to 2007 – were necessary “to remove the groundwater infiltration to prevent the basement from flooding due to the high water table here in this geographic area.” The clearwell within the powerhouse – which feeds the High Lift water distribution pump station in the same building – has its bottom slab at the same elevation as the rest of the basement.
Board responds, but is silent on leak repairs
In written comments, the Board said the drinking water “was observed to be coming from underneath the building but the source was not determined.”
A review of Board drawings of the building, including those from its original construction, found no utilities running beneath the clearwell slab, which is supported by piles. Considering the depth of the clearwell, the methods of construction involved, and the overall design of the building, placement of potable water lines 18 feet below ground and under an approximately 30 inches thick slab of reinforced concrete appears unlikely.
In response to whether they believed an elevated risk of contamination existed due to similar groundwater and clearwell water elevations – a condition prohibited by current drinking water regulations – the Board claimed the relative elevations of each had not been determined. But they did not dispute the data found in documents obtained from the agency by public records request, nor did they withdraw their 2019 statement to LDEQ about groundwater infiltration into the powerhouse basement, which is at nearly the same elevation as the Claiborne clearwell.
The Board also said they had no evidence of clearwell contamination through groundwater infiltration, evidence which they also said they could not obtain due to their inability to inspect the clearwell. Finally, they noted their regular citywide testing of drinking water, a monthly program required under federal law.
The Board did not directly respond to questions inquiring whether the leaks were repaired after August, 2021, or why the source of the leaks was never identified despite the possible risk to public health of groundwater contamination. Construction of the station upgrade project proceeded after the leaks were found, and is substantially complete now. The 15 foot deep excavations which revealed the leaks were filled in 2022 and the site has largely been restored.
Board history of running afoul of state clearwell and basin regulations
Based on rule and past practice, were the same conditions in the Claiborne station clearwell to have been found outside the plant in a portion of the city’s pressurized drinking water distribution system, the Board would have acted to meet state regulations – which require a minimum pressure of 20 psi in such piping – by issuing a boil water advisory and completing immediate repairs.
New Orleans citizens are quite familiar with those types of events, with 35 boil water advisories associated with low distribution pressure issued since the beginning of 2018. But due to the position of the leaks within finished water storage structures inside the plant – which are by their nature and design unpressurized – the 20 psi regulation does not apply. The physics and hydraulics behind the 20 psi restriction – groundwater and contaminants can flow into low pressure subsurface structures or pipes – are unaffected by regulations or lack thereof.
For storage structures within a water treatment system, other regulatory requirements exist to safeguard the potable water kept within such structures. Chief among them are multiple rules stating leaks or inadequate sealing of any kind from – or even within – portions of a treatment and storage system such as the one at the Board’s Carrollton plant are not allowed, requirements with which the Board has been familiarized repeatedly in recent years.
During a 2017 inspection of the Carrollton Plant by the state Department of Health (or “LDH”), leaks were found between basins at the start of the treatment system, a finding identical to one recorded by LDH in 2012. As in 2012, the state deemed the 2017 leaks “significant deficiencies” and required their repair. After numerous delays and deadline extensions, the Board awarded a $482,000 contract to Python Corporation in March, 2020 to inject “flowable fill” into the cracks.
In 2019, LDH found that a ground level hatch atop a subsurface clearwell at the base of the elevated storage tower at the Board’s Algiers water plant was not correctly designed to ensure contaminants could not enter, as state regulations require. Then on March 4 of this year, the Health Department found similar conditions on three hatches across the top of the below-ground clearwell in the Carrollton powerhouse, which feeds two of the eight east bank water pumps. The health department issued a notice of violation for the inadequate powerhouse clearwell hatches and required new covers with the correct design be installed by June 10.
A review of all publicly available LDH inspections, notices of violation, and follow-up documents since April 2021 confirmed LDH’s statement to The Lens that the Board did not disclose the existence of any Claiborne clearwell leaks to the state, including as part of LDH’s required triennial sanitary survey of the entire east bank water system in July 2022.
Matt McBride is a freelance writer covering infrastructure for The Lens. He began his reporting career with his blog “Fix the Pumps,” covering post-Katrina flood protection construction by the Corps of Engineers. His engineering career has spanned a wide variety of topics and concerns. He graduated from the University of Delaware with a degree in mechanical engineering.