Water Conservation: The Broken River Part 2, The Economics of Massive Water-Pipe Replacement

by Paul Robbins

TheWaterMeloonProjec/Stock.adobe.com

In This Story…

• The lower first cost of Handcox water treatment plant makes it tempting to overlook fixing old water pipes as an alternative.  But a lifecycle analysis has never been done to compare the two options.

• A preliminary lifecycle analysis of replacing old water pipe, including water savings, maintenance savings, using the system to supply more people, as well as long-term costs of water treatment maintenance and reconstruction, makes the cost of new pipe the more economic option.

The Choice of the Century

Should Austin cancel construction of the second Handcox water treatment plant and opt for water-pipe replacement instead?

Replacing all of Austin’s Polybutylene and Cast Iron pipe would save roughly 14% of Austin’s 2024 water consumption at a first cost of $1.7 billion in 2025 dollars.  (Interest is not included.)  A superficial glance would lead one to assume that, from an economic view, it would be simpler to adopt a tolerance for a considerable amount of leakage.  The first cost of a water treatment plant, about $145 million in 2025 dollars, is cheaper.

However, Austin lacks a lifecycle economic analysis comparing treatment capacity and water supply with pipeline replacement.  Since new pipelines are expected to literally last a century (by one estimate, ductile iron pipe can last 250 years), a lifecycle analysis is essential to understand the real economics.

And from a survival perspective, Austin could have treatment plants on every block, but if there is no water to supply them in the new era of climate change, these plants would be unusable.

Add to this, Austin is looking hard at expensive sources of alternative water to mitigate its Highland Lakes supply when impacted by population increases and future drought.

This author has tried to compare the cost of a massive public works project, christened the Broken River Replacement Project, to water treatment plants as well as an alternative source of water.

Handcox Water Treatment Plant Unit 2 – The first cost for an additional 50 MGD of capacity is $145 million.  (Interest is not included.)  However, all of its components can be assumed to be replaced between 1 and 4 more times.  There will also be 100 years of operation and maintenance, including employee salaries, electricity supply, and treatment chemicals.

Pipe replacement has inherent savings that water treatment plants and alternative supplies do not.  New pipes avoid the purchase of untreated water (in the case of the treatment plant, from LCRA).  They save 100 years of costs for water lost through leaks that can then be sold to customers.  And assuming that Austin densifies, with more people living in the same land footprint, more water provided with the same pipeline will bring the delivered cost down.

The average annual volume saved by this new pipe in the timespan of a century will equal the average yearly output of the treatment plant. 

According to preliminary lifecycle estimates, Handcox Unit 2 will cost between $1.07 and $1.54 per thousand gallons.  However, despite the huge $1.7 billion capital expense of the Broken River Replacement Project, as well as its upkeep, the costs range on the order of 59¢ to $1.37¢ per thousand gallons, with the midpoint below the average lifecycle cost of a new treatment plant. 

The cost range varies with the assumption that the same water pipe footprint can serve 43% more people as the city densifies.  This is less than half the population increase that is expected in Austin in the 100-year timespan.  (The low cost assumes no increase in pipeline size, while the high cost assumes a 78% increase in volume capacity.) 

Aquifer Storage Reservoir – Pipe replacement also competes well with alternative water supplies.  Austin’s utility is in the formative stages of developing an Aquifer Storage Reservoir in rural areas east of Austin.  This would initially store the equivalent of about 4 months of Austin’s current use underground, with surplus water supplied to it in rainy years.  This would be drawn on in emergencies.  

These emergencies, however, can last as long as 5 years during extended droughts.  The $1.5 billion cost for the aquifer storage and pipeline, when completed by 2035, would provide water at more than $6.36 per thousand gallons of water stored. 

Surviving a Drought is Not a Luxury

The assumptions in this 100-year comparison of the Broken River Replacement Project can be debated.  The point of publishing this challenge is that Austin Water will not debate them.  The utility is inexorably tethered to a dated business model that values new treatment plants over all else.

A megadrought only 15 years from now can trigger a dire situation where Austin can no longer depend on its historic water supplies.

A new approach is no longer a luxury.  It is a prerequisite.

SPEAK UP FOR AUSTIN's WATER FUTURE

Paul Robbins is an environmental activist and consumer advocate living in Austin.  He has been Editor of the Austin Environmental Directory, a sourcebook of green issues, products, services, and organizations, since 1995.