Dillon source water is leaching lead from fixtures and supply lines, town awaits state approval for methods to raise pH

Dillon townsite prior to construction of Dillon Reservoir via Denver Water

From The Summit Daily (Sawyer D’Argonne):

During recent testing mandated by the Colorado Department of Public Health and Environment at 20 different sites earlier this year, the town discovered that seven had lead levels in excess of the state’s maximum allowable limit of 15 parts per billion. The finding comes just months after Frisco discovered a similar issue in their sampling pool.

Dillon officials stress that the town has good, clean surface water.

“We don’t have lead in our source water,” said Scott O’Brien, Dillon’s public works director. “We’ve monitored for that, and it’s not the issue. … The issue is the materials that were used prior to 1987 for constructing homes, copper pipe with leaded solder. In addition to that, a lot of fixtures like faucets were constructed with either brass or bronze — metal alloys that contain lead.”

O’Brien said that because the source water is so “aggressive,” it’s leeching the lead out of older pipes and fixtures at testing sites, resulting in the elevated rates. In determining aggressiveness, the town looks at four main factors: pH levels, alkalinity, temperature and hardness.

The pH level in the water measures how acidic or basic the water is on a scale of 0 to 14 — anything below 7 is considered acidic, and anything higher is considered basic. In general, high acidity means the water is more corrosive, and more likely to leech metal ions like lead and copper. Dillon’s source water is naturally about 7.3, or slightly leaning towards the basic side.

Alkalinity is a measure of the buffering ability of the water, essentially the ratio of hydrogen ions versus hydroxide ions that determines the water’s ability to neutralize acid. O’Brien noted that Dillon’s water has low alkalinity. Temperature is self-explanatory, literally describing how hot or cold the water is — wherein hotter water is more reactive and aggressive than cold water. Hardness measures the mineral concentration in the water, or what it’s naturally picking up as it flows along. Because Dillon uses its source water so quickly, it is relatively soft.

“We’re the first in line to pick it up, and it doesn’t have the chance to pick up these other minerals and other things that help reduce the aggressiveness of the water,” said O’Brien.

This is a problem that Dillon has dealt with in the past. The town’s testing also returned high lead levels in both 2012 and 2014, and officials have been working with the state since to address the issue. In 2014, the town attempted to adjust the pH levels up to about 8.5 on the scale, which appeared to have worked over the last five years. Though, due to recent changes in regulations from the state level — which essentially requires towns to zero in on high-risk testing sites to determine the worst-case scenarios for water quality issues — new issues are being discovered.

“To get a representative sample pool they don’t want us to go over the distribution system geographically, and sample it spread out,” said Mark Helman, chief water plant operator. “They want us to sample these particular sites built from 1983 to 1987 (before the Lead Contamination Control Act in 1988) they know are going to give us the worst results. … This is a process of us learning where the worst sites are that we have, testing those sites, seeing how our water is doing at those sites, and if we have a problem we want to address the worst case scenario.”

Both O’Brien and Helman noted that they already have a plan to try and address the issue of overly aggressive water. The plan is to add soda ash — sodium carbonate or baking soda — during the water treatment process to increase pH levels, alkalinity and hardness to the water to reduce aggressiveness. However, because it includes changes to the plant, the new process must first be signed off on by the state.

O’Brien said that once the state approves the town’s new water treatment methods they’ll be able to implement the new process quickly, though the review process could take between 30 and 60 days.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.