Water Utilities Supply Chain
Challenges and Case Studies:

CHLORINE AND THE TRINITY RIVER AUTHORITY

The Trinity River Authority (TRA) of Texas is a
conservation and reclamation district that provides
drinking water and wastewater treatment, along
with recreation and reservoir facilities, within the
nearly 18,000-square-rnile Trinity River basin. TRA
owns and operates five wastewater treatment plants
(WWTPs) and four water treatment plants (WTPs).
Tarrant County Water Supply Project (TCWSP)
is the largest WTP operated by TRA. TCWSP is
rated for 87.0 million gallons per day (mgd), and it
provides drinking water to approximately 250,000
customers in 5 cities. TCWSP relies on their
chemical supplier to provide various chemicals for
water treatment needed to protect the environment
and their customers. Chlorine plays an important
role in maintaining a chlorine residual within the
distribution system.

Located in the North Central region of Texas, TCWSP
has worked on supply chain management practices
to both optimize normal operations and withstand
climate events such as drought, hurricanes, and
extreme heat. However, these best practices were
put to the test by Winter Storm Uri in February of 2021.

The Deep Freeze Arrives with
Winter Storm LJr

During winter, outside temperatures in Texas are
typically kept cool, not cold, by the relatively warm
Gulf of Mexico waters. But during Uri, temperatures
fell below freezing for 11 days, with a low temperature
of 2°F. Water demand soared to more than two
times its normal winter levels as people ran faucets
to keep pipes from freezing, increasing the need for
treatment chemicals like chlorine.

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To prepare for Uri, TCWSP maximized water storage
throughout its system and ordered additional chlorine
to top off its tanks. However, the day before the
chlorine delivery was due, the supplier called TCWSP
and informed them that due to winter weather road
conditions there would be no chlorine delivery.

Despite the chlorine shortage, TCWSP could not
afford to lose its ability to treat and distribute water
during the storm, especially since many customers
were experiencing additional hardships such as loss of

TCWSP Water Demands



	Year 2020



	Year 2021

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power and no heat. This result was not acceptable to TCWSP. Staff accepted the challenge to maintain their
current supply and to locate and procure additional chlorine.

Response arid Mitigation

Chlorine has several uses in water
treatment, including primary and residual
disinfection, algae control, oxidation of
taste & odor compounds, and on-site
generation of chlorine dioxide. But water
treatment applications account for only 4%
of domestic consumption. Therefore, during
shortages, it can be hard for water utilities
to compete with larger industrial users such
as pulp and paper, pesticides, rubber, and
solvent manufacturing.

TCWSP immediately implemented a multi-pronged
approach, which included the following:

•	Advised wholesale customers to activate their
Drought Contingency Plans. Implementation
of Drought Contingency Plans reduced water
demand, but it remained above typical winter
demand levels.

•	Located a back-up chlorine supplier. There are
only two suppliers of bulk chlorine in Texas and
TCWSP was under contract with one supplier.
TCWSP contacted the other supplier for
assistance.

•	Used bleach (sodium hypochlorite) as a
supplemental disinfectant. TCWSP keeps
bleach on-site to provide disinfection at one of
its pump stations.

•	Contacted the Texas Water and Wastewater
Agency Response Network (TXWARN) in hopes
that a less impacted utility would be willing to
share chlorine with TCWSP.

•	Determined if the City of Fort Worth could
provide emergency water. TCWSP has an
agreement with the city to provide emergency
water through an interconnect. However, in this
State-wide incident, the city was impacted as
well so this option was quickly removed from
further consideration.

While none of the options above could manage
the issue alone, TCWSP was able to adapt and
combine portions of each option to arrive at an
acceptable solution without compromising service.
For example, although the other supplier of bulk
chlorine was not able to deliver chlorine right
away, it was able to obtain chlorine in Oklahoma
and eventually deliver the needed amount. While
TRA awaited the chlorine delivery, they were able
to successfully blend bleach with the limited bulk
chlorine supply on hand to successfully treat water
and meet demand until the bulk chlorine arrived.
TXWARN also assisted with the delivery of one-ton
chlorine cylinders to supplement the bulk chlorine.

Although, the cylinders were not used, they
provided an additional standby supply of chlorine

in case they were needed. Also critical to success
was the implementation of Drought Contingency
Plans which reduced demand and allowed for
further "stretching" of not only water in storage but
also the limited bleach and bulk chlorine supplies.

Ultimately, the cities maintained their drought
emergency status for two weeks. Blending bleach
and existing chlorine supplies worked well to
maintain the needed chlorine residual. TCWSP's
supplier for bulk chlorine was able to supply bleach
to TCWSP during the incident, which helped TCWSP
to maintain the blended disinfection process until
the alternate chlorine supplier was able to deliver
bulk chlorine. Chlorine was delivered three weeks
after the original scheduled delivery and TCWSP
was able to resume normal operations. The bleach
delivery system was disassembled, excess bleach
was returned to TRA's supplier, and the unused
one-ton chlorine cylinders were returned to the
respective utilities that provided them under I RA's
request to TXWARN.

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Lessons Learned

A combination of actions helped the utility weather the storm. The incident led to the following lessons
learned for enhancing these practices:

•	Improve supplier communication. Since the
incident, TCWSP has increased communications
with their bulk chlorine supplier.

•	Establish an emergency back-up supplier

TCWSP identified and utilized a back-up supplier
to secure additional bulk chlorine during the
incident. TCWSP is considering establishing a
contract with this supplier as an emergency
vendor should another shortage occur.

• Maintain emergency supplies for employees

TCWSP had procured extra supplies for its
employees as part of its COVID-19 planning
and response. These included pre-packaged
meals, cots, and bottled drinking water for field
use. These supplies proved useful during Winter
Storm Uri as staff spent long hours at the utility.

Additional Resources

You can find more information on using supply chain
management best practices and preparing for supply chain
challenges at https://www.epa.ciov/waterutilitvresDonse/
water-and-wastewater-sector-supplv-chain-resilience.

While TCWSP cannot predict when another Uri or similar disaster may occur, they can and are taking steps
to better plan for and respond to a similar incident in the future by working with their supplier, mutual aid,
and exploring sustainable changes to enhance resilience at their facilities.

Office of Water (4608T)

EPA 830-F22-001

July 2022

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